Could LxxLL be a key to a New Site for Target Drugs?

We have mapped the entire human genome. We have discovered specific site targeting drugs that have been a huge success in killing cancer. What is next? Of course to further embark on this newly discovered path and target other genes for success! 

How do these targeting drugs work? Lets look at the human papillomavirus (HPV) vaccine. This vaccine is preventing strains 16 and 18 from infecting women.These strains are the cause of at least 70% of cervical cancer cases. When HPV infect someone, it acts as a retrovirus. It copies into human DNA. Then, it makes an E6 protein. This protein is not equivalent to the human one, but from HPV. This E6 protein floats around cells and attaches with ubiquitin ligase, a protein that degrades genes from doing their job. There is a domain on this E6 protein that start with Zinc C domain and terminates with a Zinc N domain. In between is a linker helix domain that is very hydrophobic. This makes up the LxxLL sequence with L being acidic Leucine and x being other hydrophobic amino acids. This hydrophobic pocket then binds with extreme ease to proteins like p53 and RB. When they are in contact, ubiquitin ligase then deregulates the protein E6 is bound to. In turn, this then causes no tumor suppression or cell death and cancer develops. Because HPV is sexually transmitted almost all of these cases result in cervical cancer. 

  Figure 1: E6 protein structure when bound with ubiquitin ligase.
The top image shows the structure of the folding of the E6 protein, in yellow is the first Zinc domain, in grey is the linker helix domain and in purple is the terminal Zinc domain. The bottom images shows the hydrophobic LxxLL pocket. 

A crucial point to notice in this process is that the LxxLL pocket can bind with a plethora of different proteins. Targeted therapies do just this. If we could make a drug/ structure that has a pocket like LxxLL that could go in and bind to proteins that are mutated, we could used this process to treat cancer. This is especially important because proteins like RB and p53 are in almost all cases of cancer and there has not been much research done on these oncoproteins. Targeting drugs have proven in the past to be very successful in curing targeted cancer. This specific pocket could be useful for further research in this field.

Even though this started with the HPV vaccine which does not cure cancer, it prevents it, if science found the technology to to build a protein that when inserted into a cancer cell could latch onto mutated proteins and regulate them again, we could help cure many forms of cancer. Evidence shows through the HPV that it really does work. Our next step is to instead of using it as a prevention, we use this technology as a cure. By knowing how HPV attacks proteins we can do the same with an artificial structure. If we went after proteins as common in mutations as p53 and RB we could change many lives. I would love to see further research on this LxxLL pocket. I feel that having a technology break through would come best with furthering our knowledge on targeting mutations on proteins that influence all cancers. This pocket could be the start of a new era in cancer research. 



Work Cited:

Zanier, K., S. Charbonnier, A. O. M. O. Sidi, A. G. Mcewen, M. G. Ferrario, P. Poussin-Courmontagne, V. Cura, N. Brimer, K. O. Babah, T. Ansari, I. Muller, R. H. Stote, J. Cavarelli, S. Vande Pol, and G. Trave. "Structural Basis for Hijacking of Cellular LxxLL Motifs by Papillomavirus E6 Oncoproteins." Science 339.6120 (2013): 694-98. Web. 12 May 2014. <http://www.sciencemag.org/content/339/6120/694.full>.

Epithelial-Mesenchymal Transition on CTCs

In my previous blog post I mainly addressed the issue of factors that affect circulating tumor cell count in blood samples. As previously mentioned, this could lead to an under or overrepresentation of the cumulative CTC total within the patient. As such, it is important to account for these factors during quantification and ultimate prognosis using CTCs. In my previous post I focused more on the factors of clustering and filtration. The factors that followed, such as cloaking had to do with molecules from within the circulatory system masking CTC presence and as a result prevented accurate analyses to the point where it was deemed another factor in distorting CTC measurement. However one of the factors that was in the article mentioned, but was never given a greater insight to is G in the image below labeled “(partial) EMT”. 

Mechanisms For Trastuzumab Resistance

My cancer project looked at a possible mechanism for Trastuzumab resistance, this being AMF causing HER2 phosphorylation leading to intracellular signaling. While this idea is interesting it is fairly new so I wanted to do more research on what is widely accepted today as the mechanism for Trastuzumab resistance. Trastuzumab is a monoclonal antibody that specifically targets the HER2 receptor. A monoclonal antibody is a synthetic molecule whose primary role is to attack a certain defect in a cancer cell. These antibodies also cause cancer cells to become more visible to the immune system, thereby causing an immunogenic response. Trastuzumab binds to HER2 extracellularly and this causes HER2 to become deactivated. This ceases all signal transduction, which leads to inhibition of both the MAPK pathway and the pi3k pathway. However, the majority of patients with metastatic breast cancer develop a resistance to Trastuzumab within a year. How does this happen?

Cholesterol and Cancer Inhibition

For our project, Matt and I focused on cholesterol and its metabolite’s promoting effects on breast cancer.  However, as Matt mentioned in our presentation, there is a tumor suppressing metabolite of cholesterol.  It is still very much in the works, but research seems to support the suppression of this metabolite, called Dendrogenin A (DDA).  This molecule is an amino-oxysterol metabolite that “arises from cholesterol-5,6-epoxides and histamine in mammals” (Silvente-Poirot).  Very little is actually known about this molecule and its inhibitive abilities, and a Google search turned up this study and one other that identified DDA as a product of cholesterol.  It has recently been discovered to be a natural metabolite occurring in mammals, having been previously synthesized synthetically.  The fact that this molecule may be a successful inhibitor of cancer makes it very exciting.  The fact that it is naturally occurring makes it even better.

We Are All Mutant

Mel Greaves' article "Does everyone develop covert cancer?" discusses that while around 1 in 3 individuals will develop overt cancer, there is increasing evidence that most, if not all, people in their lifetimes develop covert cancer. Greaves begins by defining covert cancer as cancer that is "hidden and subclinical" but that can be "uncovered by more incisive interrogation," as opposed to overt cancer, or full-blown, malignant growths or tumors. The evidence for these covert cancers is primarily gathered from autopsies of individuals who died for non-cancerous reasons. Most autopsy reports show a substantially higher frequency of pre-malignant lesions, or carcinoma in situ (CIS), than of clinical cancer frequencies or cumulative life-time risk of developing overt cancer. This suggests a much higher frequency of CIS than is commonly believed or recorded.

Panitumumab versus Cetuximab - Treatment in Metastatic Colorectal Cancer

Throughout all our research about anti-EGFR treatment in metastatic colorectal cancer, my partner Tien Lu and I often discovered panitumumab and cetuximab as main-line therapies (More in our wiki). Both of these drugs are anti-EGFR treatments. EGFR is the epidermal growth factor receptor, which contains many pathways that lead to cell proliferation and survival. Therefore, it is no surprise EGFR as been important in the study of cancer, as malfunction in its pathways can lead to uncontrollable cell growth, differentiation, and migration. Typically, EGFR ligands bind to the EGFR cell surface receptor to induce cell signaling down the pathway, leading to cell replication. Monoclonal antibodies are anti-EGFR treatment, and bind to the EGFR receptor instead, blocking the downstream signaling and stopping cell proliferation.

Five or More Blistering Sunburns Before 20 Increases Melanoma Risk by 80%

I thought this post would be particularly fitting with summer right around the corner.

I was doing some reading and came across this article, which summarized a study that examined the relationship between sun exposure (along with some other risk factors) and the risk of different types of skin cancers. In this study, researchers were able to follow 108,916 US women over 20 years and determined that having five or more blistering sunburns between ages 15 and 20 resulted in an 80% increased risk for melanoma. Moreover, women in the same age range had a 68% increased risk for basal cell carcinoma and squamous cell carcinoma after having five or more blistering sunburns.

Cancer and Personalized Medicine

If you recall we spent week five of the course discussing the different treatments available for those who have cancer. During the week, we discussed the three most common methods of treatment, those being: surgical oncology, radiation therapy, and medical oncology. Surgical oncology mainly takes place as a treatment in the form of a resection of a solid tumor with wide margins to ensure complete removal. Radiation oncology uses x-rays and carbon ions to directly damage DNA of the cancer cells in hopes the damage will prevent continued growth. Lastly, we discussed medical oncology, wherein we discussed chemotherapy. When we discuss personalized medicine we are generally referring to changing the way in which we use medical oncology.

Will This Man Cure Cancer?

While in the passenger seats of one of my housemates car, I picked up a Forbes magazine from the dashboard published in May 2014.  The large block lettering on the cover read "WILL THIS MAN CURE CANCER?" below a picture of a professional looking man in a full suit.  After spending ten weeks studying many different topics regarding cancer research,  I wondered what this business/financial news based magazine was to say about curing cancer.  The man on the cover is Joseph Jimenez, the CEO of Novartis, a Swiss pharmaceutical company.

  Jimenez plans to "double down" on cancer related drugs by spending the majority of Novartis' budget on cancer therapies.  According to Forbes, Jimenez is a man that should be listened to when it comes to making money.  He transformed Gleevec(tyrosine-kinase inhibitor) from a 400 million dollar annual profit to a 4.5 billion dollar annual profit.  The six page article begins by discussing the case of a five year old girl diagnosed with acute lymphoblastic leukemia(ALL).  Today 85% of ALL patients are cured with FDA approved chemotherapeutic treatment.  This particular young girl is part of the remaining 15% uncured patients.  Her cancer returned while she was waiting for a bone marrow transplant.  Oncologists decided to try a treatment in which they removed blood from the patient and passed it through a machine which removes white blood cells.  They used a modified HIV virus to genetically reprogram those white bloods cells so they would attack cancer cells.  I decided to further research this process of immunotherapy described without much detail in Forbes magazine.

AAC-11 Newly Linked to Cervical Cancer

Introduction
Researchers have found a new genetic link to the development of metastatic cervical cancer. This article discusses how the overexpression of the gene AAC-11 leads to the production of other proteins that induce anti-apoptosis effects in the cell. The researchers found that levels of expression of AAC-11 were low in normal cervical tissue as well as cervical tissue that is in the early stages of becoming cancerous. The levels of AAC-11 increased by 200 to 400% in cervical cancer that had invaded regional lymph nodes or became metastatic (1). This indicates that AAC-11 is not the primary mutation that leads to the development of cervical cancer; rather, it is a mutation that occurs after the cancer develops but aids the progression by inhibiting apoptosis.

Telomerase Peptide Vaccine Tested in Pancreatic Cancer Patients

Telomerase is expressed in 80-95% of cases of pancreatic cancer making it a viable target for cancer therapies.  It follows that a Norwegian study explored the creation of a telomerase peptide vaccine for research subjects with non-resectable (inoperable) pancreatic cancer.  This study was a combined phase I and phase II trial aimed at discovering the proper dosage of the vaccine and its efficacy by measuring its safety, tolerability, and immunogenicity, as well as patient survival.  The peptide chosen for this vaccine, GV1001 is a "promiscuous HLA (human leukocyte antigen) class II epitope", meaning that it is the part of an antigen that the immune system recognizes and binds in a nonspecific manner to HLA molecules.

Further Hindrance in CTC measurement

     My partner’s previous post illustrated several issues which might change the number of detected CTCs in the bloodstream. While the study of CTCs holds many possibilities, my partner made a fair point to discuss that they have a fair number of limitations. One such limitation that he described was entrapment, in which CTCs sometimes get clogged within the capillaries, causing them to be underrepresented in blood samples. In my research I also stumbled upon similar phenomena in which the rate of CTC flow seemed to fluctuate. One particular study looked into the rate of CTC flow in both large and small blood vessels for both melanoma and breast cancer. The figures below display the results for these tests.



TA-65: An Anti-Aging Drug or a Cancer-Facilitating Drug?

There have always been people who have feared growing old and the decline in health associated with aging. However, people with these fears may no longer have to worry thanks to TA-65, an anti-aging drug. Isolated from various species of the Astragalus plant, TA-65 (Cycloastragenol) helps prevent aging by activating telomerase, which results in increased telomere length and ensures that cells stay healthy and live on. People have been taking the drug for a while now, and apparently it works pretty well for them. You can listen to some of the testimonials of people taking TA-65 here. But for all the good TA-65 has done for people already, others are very concerned that TA-65 theoretically increases the risk of oncogene-mediated cancer.

27HC, CYP27A1, and Breast Cancer

Myself and Erik Christensen are investigating the relationship between breast cancer and cholesterol for our Cancer Project. In our presentation we are going to give you a brief overview about what 27HC was, but I wanted to blog a little more in-depth about it. In addition, I wanted to introduce CYP27A1 and its effect on 27HC and breast cancer as we won't be discussing that aspect of our topic in our presentation.

The Cholesterol Metabolite 27-hydroxycholestorol (27HC) promotes cell proliferation. Specifically, in this case we are looking at its promotion of ER positive breast tumors. What makes 27HC different is the fact that it is an abundant primary metabolite of cholesterol. Because of its relationship with cholesterol it can attach to and actually stimulate estrogen receptors in the body. Since 27HC is a cholesterol metabolite transported in the same lipoprotein particles as cholesterol, there was a positive association between lipoprotein particles and cholesterol. Patients with ER+ breast cancer have higher amounts of 27HC in breast tissue than women who have not been specifically diagnosed with ER+ breast cancer. Below you can see the process of cholesterol synthesis and where 27HC stands in comparison to cholesterol.

The precedent behind 27HC that we wanted to try and see was if it really did have an effect on breast cancer. In order to determine if 27HC was indeed a promoter of ER positive breast cancer study was conducted with mice. The goal was to determine if 27HC promoted MCF-7 cell growth (Nelson, et. al. 2013). As we can see in Figure 1A, 27HC promotes MCF-7 cell growth. Due to unesterified plasma levels approximating to 10−8M, the threshold concentration for activation of MCF-7 cell proliferation was 10−8M. This can be seen in figure 1B.

Figure 1. 27HC promotes MCF-7 cell and Ishikawa cell proliferation, and in vivo 27HC stimulates MCF-7 cell xenograft growth and a uterotrophic response. A–D. Cell proliferation was evaluated by quantifying BrdU (A) or 3H-thymidine incorporation (B–D), n= 4–8. A. Growth responses of MCF-7 cells to E2 (10−8M) or 27HC treatment (10−8 to 10−6M) for 24h were compared. B. The dose-response of MCF-7 cells to 27HC (10−9 to 10−6M, for 24h) was determined. C. The requirement for ERα in the growth response of MCF-7 cells to E2 (10−8M) or 27HC (10−6M) was evaluated in cells treated with methyl-piperidino-pyrazole (MPP, 10uM) for 24h. D.

So with this information it would be wise to see the potential impacts of 27HC on ER+ breast cancer. Since 27HC is a cholesterol metabolite transported in the same lipoprotein particles as cholesterol, there was a predictable positive association between serum 27HC and cholesterol in both controls and cancer patients. We can see that this was eventually proven to be true in Figure 2C and 2D. In addition, compared with controls, there was a 3 fold greater 27HC concentration in normal breast tissue from cancer patients than controls. 27HC levels were 2.3 fold higher in the breast tumor itself than in the breast tissue.

27HC content is increased in normal breast tissue and tumors from ER+ breast cancer patients, and it is locally modulated. A,B. Serum 27HC (A) and total cholesterol concentration (B) in control and breast cancer patients (n= 17 and 58, respectively). Values for 10 cancer patients with serum 27HC greater than 2SD above the mean value for controls are shown in red. C,D. Relationship of serum 27HC to serum cholesterol concentration in controls (C, n=17) and cancer patients (D, n=58). E. 27HC content in normal breast tissue from controls (n=17) and cancer patients (n=48), and in tumors (n=32). *p<0.05 vs control, †p<0.05 vs cancer patient normal breast. F,G. Relationship of normal breast 27HC content to serum 27HC in controls (F, n=17) and cancer patients (G, n=40). H,I. Relationship of tumor 27HC content to serum 27HC (H) or normal breast 27HC content (I) in cancer patients (n=27).

Along the same lines, CYP27A1 is a gene sometimes referred as sterol 27-hydroxylase. Generally, it is expressed in the macrophages of the cell. We are interested in it because it is required for the conversion of Cholesterol into the metabolite 27HC. Interestingly enough, no matter whether macrophages of the breast tissue were malignant or benign, they consistently stained positively and strongly for the CYP27A1 protein. With an already established connection between macrophage infiltration and breast cancer (Wu, et al. 2013), we clamored to try and find other data and studies that incorporated this connection between the macrophage and breast cancer.

There were a couple of important findings from the next set of data we found research. The first was that (bone derived) macrophages were unable to support MCF7 cell proliferation when treated with CYP27A1 inhibitors. More importantly, introducing 27HC could reverse the effects of the CYP27A1 inhibitors. With the reversal process so effective, this indicated that local production of 27HC by macrophages in the tumor has a high impact on tumor pathology. The second observation was that CYP27A1 was expressed in the cancer cells themselves. From the data, the determination can be made that the expression was based on the size of the tumor. This can be seen below.

Table 1. Overexpression of CYP27A1 increases the likelihood of a higher tumor grade. Results of immunohistochemical analysis of CYP27A1 expression in human breast cancer tissue microarrays are shown. CYP27A1 expression was determined to be low or high and correlated with tumor grade. A Fisher’s exact test was used to determine P values for the likelihood of association. Ordinal logistic regression was used to estimate the odds ratio. N, sample number; N/A, not applicable (because sample number is too small).

The second main area studied was CYP27A1’s relation to a high cholesterol diet. In order to do this, researchers performed a study on mice where a group of mice was fed a high cholesterol diet from birth and another group on a control diet from birth. In addition to the different diet, both CYP27A1 positive and negative mice were tested on either one diet or another. The results show that CYP27A1 positive mice on a high cholesterol diet developed larger tumors faster and earlier than the mice on the control diet. Furthermore, the tumors were tested and those mice with the high cholesterol diet were found to high much higher levels of 27HC in the tumor than those mice that ate a controlled diet. Most surprisingly, the CYP27A1 negative mice had undetectable levels of 27HC in tumors and tumors formed much later and grew lower. Lastly, if the CYP27A1 negative mice that were fed the control diet were injected with 27HC, they started to produce the same exact results as the CYP27A1 positive mice on the high cholesterol diet. 

Genetic or pharmacological inhibition of 27HC production attenuates hypercholesterolemia- promoted tumor growth in mice. The latency and growth of tumors in the MMTV-PyMT mouse model of breast cancer were evaluated in mice in which the conversion of cholesterol into 27HC was inhibited by disruption of the CYP27A1 gene (CYP27A1−/−). For this study, MMTV-PyMT mice were bred onto a CYP27A1+/+ or a CYP27A1−/− background. (A) Tumor latency and (B) tumor growth were measured in mice on a control diet (CD) or a high-cholesterol diet (HCD) from weaning. Note that in the tumor growth studies, daily injection of 27HC overcame the inhibitory effect of CYP27A1 deletion. Significance between curves is indicated by a connecting black line and an asterisk (P < 0.05, n = 9 to 25).

In my opinion, this is the study’s most significant finding because it indicates that 27HC is the direct breast tumor promoter. In addition, the d at a hints that cholesterol metabolite 27HC stimulates MCF-7 cell growth in mice and lastly, in ER+ breast cancer patients, 27HC content in normal breast tissue is increased compared to cancer-free controls, and tumor 27HC abundance is further increased.

References:

1. Nelson, E. R., S. E. Wardell, J. S. Jasper, S. Park, S. Suchindran, M. K. Howe, N. J. Carver, R. V. Pillai, P. M. Sullivan, V. Sondhi, M. Umetani, J. Geradts, and D. P. Mcdonnell. "27-Hydroxycholesterol Links Hypercholesterolemia and Breast Cancer Pathophysiology." Science 342.6162 (2013): 1094-098. Web.
2. Wu, Qian, Tomonori Ishikawa, Rosa Sirianni, Hao Tang, Jeffrey G. Mcdonald, Ivan S. Yuhanna, Bonne Thompson, Luc Girard, Chieko Mineo, Rolf A. Brekken, Michihisa Umetani, David M. Euhus, Yang Xie, and Philip W. Shaul. "27-Hydroxycholesterol Promotes Cell-Autonomous, ER-Positive Breast Cancer Growth." Cell Reports 5.3 (2013): 637-45. Web.
3. Umetani, Michihisa, and Philip W. Shaul. "27-Hydroxycholesterol: The First Identified Endogenous SERM." NIH (2011): 1-10. National Institute of Health. Web.
4. Bianchi F, Kaaks R, Viano H. Overweight, obesity, and cancer risk. Lancet Oncol. 2002; 3:565-574. Web

Clinical Trials to Support KRAS Mutations and Cetuximab Resistance

To conclude my series of blog posts, I will focus on the last important piece of the paper that I have been dissecting. My other posts focused on the data of the cellular models used to explain the molecular basis of the secondary acquired resistance. Through two different models, the authors concluded that KRAS amplification and/or mutation had an effect on resistance to cetuximab. To determine if these conclusions are clinically relevant, the researchers examined tumor biopsies from colorectal cancer patients.

Crohn's Disease as a potential risk factor for Gastrointestinal Cancer development

At the age of ten, I was diagnosed with a Gastrointestinal condition known as Crohn's Disease. While this introduced several complications such as immune system compromise, severe abdominal pain, and difficulty with weight gain, I have since brought my condition under control, I am for all intents and purposes healthy and stable! Having a condition, however, pushes you to the brink of curiosity. Though I have learned a lot about Crohn's since being diagnosed, I have always wondered if a correlation exists between development of this disease and cancer risk. To my surprise, I stumbled upon a study conducted in Denmark looking specifically at patients with Crohn's disease and the resulting risk of cancer development.

A closer look into CYP7B1

As our project progresses, Matt and I are starting to delve deeper into many of the topics associated with cholesterol and cancer.  One of these very important topics is 7ɑ-hydroxylase (usually referred to by its gene name CYP7B1), a very important enzyme that works to hydrolyze the infamous 27-hydroxycholesterol (27HC).  27HC is a cholesterol metabolite that has recently been shown to promote ER positive breast cancer.  This is really all you need to know about this molecule.  However, for more information on 27HC, you can search the blog for my earlier post Cholesterol and its Promotion of ER+ Breast Cancer.  If you are unable to find my post, follow this link to another information page for 27HC.

Oral Contraceptives effect on Breast and Ovarian Cancer Risk

       In Megan and Christina's presentation, they discussed how the increased level of estrogen and progesterone during pregnancy causes breast tissue to differentiate and ultimately decreases risk of developing breast cancer. Because most combination birth control pills contain both estrogen and progesterone it made me curious about if the use of oral contraceptives can have similar effects of pregnancy and decrease risk of breast cancer. However, the information I found was opposite of what I had anticipated.

Tumor Suppressor Functions and Mutations of NOTCH1 in HNSCC

Figure 1. Duality of Notch functions in keratinocyte commitment to differentiation and cell survival. Notch signaling impacts on, and is regulated by a complex signaling network with an important role in skin homeostasis and tumor development. Like Notch, many other components of this network exert a duality of functions, impinging on keratinocyte growth/differentiation control as well as cell survival. This has potentially important implications for cancer therapy. An attractive approach could be the use of selective inhibitors, which can suppress the Notch prosurvival function while leaving intact or enhancing its ability to induce differentia- tion. Alternatively, Notch inhibitors, or inducers, could be used as part of a combination therapy in conjunction with other compounds with growth inhibitory and/or pro-apoptotic functions. 

KRAS Mutations and Acquired Resistance to Cetuximab

Throughout my blog posts, I have been looking closely at a paper whose authors claim that KRAS mutations cause acquired resistance to an anti-EGFR therapy drug called cetuximab for colorectal cancers. My last blog post examined the data of one of the cellular models, DiFi, and now I will do the same for the other, Lim1215. These cellular models are used to help define the molecular basis of this secondary resistance, which in the future can help prevent such matters. Lim1215 cells express normal levels of EGFR, while DiFi overexpressed EGFR, but both are similarly sensitive to cetuximab.

Autocrine Motility Factor

Our project’s topic illustrates how AMF induces phosphorylation of the HER2 receptor and thus activates its signaling pathway. HER2 breast cancer is when the breast cancer cells have an amplification of HER2 2 receptors on the surface of the cell. With this increased number of receptors cell proliferation is increased resulting in cancer. HER2 breast cancer is often treated with the Trastuzumab(Herceptin) drug. This drug works by first attaching onto the HER2 receptor on the extracellular side, which then stops the receptors from signaling downstream. Many patients who take Herceptin become resistant to its effects. My group will explore the theory that the interaction between AMF and HER2 causes the resistance to the drug. AMF’s phosphorylation of HER2 activates phosphoinositide-3-kinase and mitogen-activated protein kinase signaling. This happens regardless of Herceptin involvement. This is important because the AMF-HER 2 interaction may be a viable target for therapeutic treatment of patients with breast cancer.

Beyond Standard Therapies in Metastatic Colorectal Cancer

After all standard therapies for treating metastatic colorectal cancer are exhausted, there are no interventions to improve the quality or length of life of the patient. However, patients with cancer that progresses despite therapy are possible candidates for further intervention. One therapy that can be used is multikinase inhibitors. They block intracellular and cell surface kinases, some of which are involved in tumor growth and the metastatic progression of cancer. These multikinase inhibitor drugs can reduce cell replication and tumor growth and are used to treat cancer in advanced stages. For metastatic colorectal cancer, a phase 3 trial was done internationally for the multikinase inhibitor Regorafenib.

Notch1 Helps or Hinders Tumor Formation in Conjunction with HPV?

In HPV positive cervix cancer, one cannot develop cancer solely from having HPV; additional mutations, such as NOTCH1 mutations, are necessary to instigate tumorigenesis. Different studies have yielded contradictory results of whether Notch1 acts as either a tumor suppressor protein or an oncoprotein in HPV positive cervical cancer. In this article1, the authors observed that when Notch1 is expressed excessively, it acts as a tumor suppressor in HPV positive cervical cancer; however, when it is expressed in moderate amounts in conjugation with constitutively active PI3K, it presented oncogenic properties.

Sunscreen and p53: A Case Study

In my recent blog post, I discussed the p53 gene, and experiments testing sunscreens effect on p53 in mice. In this blog post, I will discuss a study testing sunscreen’s relation to p53 protein production done on humans. From 1992-1996, the NambourSkin Cancer Prevention Trial conducted a study to test the association of time spent outdoors and the expression of p53, as well as its relation to the use of sunscreen. Researchers predicted that sunscreen counteracts p53 production, and carried out their research on over 160 random participants for 6 months. There were four different treatment groups: 1. Application of SPF 16 sunscreen daily + beta-carotene supplementation, 2. Application of SPF 16 sunscreen daily + placebo tablets, 3. Beta-carotene only, 4. Placebo only. Beta-carotene is a type of pigment called a carotenoid, and produces Vitamin A, which helps prevent cell damage. It’s thought to be possibly effective for people who are sensitive to sun exposure in order to help prevent sunburn, but the exact efficiency is not known.

The CRISPR/Cas9 genome editor and its therapeutic potential

In the first few weeks of the quarter we had a lengthy discussion on the origins of cancer cells. Loss of function mutations in tumor suppressor genes and gain of function mutations in oncogenes lead to the deregulation of the cell cycle and eventually uncontrolled cell proliferation. Gene therapy has been considered as an option to rehabilitate these genes back to a functional state. Unfortunately, the methods researched in the last three decades since the principle discovery of gene therapy, such as retroviral vectors, have been incredibly inefficient and have a low ceiling due to inherent low indel (nucleotide insertions or deletions) specificity. Within the last fifteen years though, three restriction enzymes (used to cut DNA at relatively specific sites) have been heavily researched in hopes of finding a mechanism to make the ultramodern form of gene therapy a reality.

Reactivated Telomerase and Prostate Cancer in Mice

In order to determine the role of telomerase in prostate cancer, researchers used a mouse model that was null for Pten and p53, meaning that these tumor suppressor genes lacked proper function and couldn't produce viable proteins.

Beer: As a Risk To Your Health or as Cancer Prevention

Barbeque on a sunny afternoon is one of the most common activities of many average Americans. The charred, heated part of meat on the grill are the pieces that many of us like most about our meat, but evidence has been shown that these are made up of carcinogenic substances.

A negative side effect of BRAF targeted drug therapy with a promising future

In my last blog post I wrote about a new promising drug called dabrafenib, but some negatives about this drug included resistance and side effects.  In order to address the issue of resistance, a drug that targets a different part of the MAPK signaling pathway called trametinib is used in drug combination therapy.  In chemotherapy using just dabrafenib there was a response rate of 56% and in combination therapy there was a recorded response rate of 76%.  Dabrafenib targets the BRAF protein while trametinib targets the MEK protein, which can be seen in Figure 1.

YOU Can Kill Your Own Cancer! Immunotherapy and Metastasis

     A new method of immunotherapy developed by researchers at the National Cancer Institute has proven successful in the reduction of a metastasized tumor size by specifically attacking tumor cells that have mutations unique to a patient's cancer. The researchers demonstrated that the human immune system can mount a response against mutant proteins expressed by many common cancers that arise in epithelial cells which can line the internal and external surfaces of the body. 

KRAS Amplification and Acquired Resistance to Cetuximab

In my last blog post, I examined questionable factors of a paper whose authors conclude that KRAS mutations drive acquired resistance to an anti-EGFR therapy drug called cetuximab for colorectal cancers. My main concern is with the strength of the authors’ conclusion and if the data is sufficient enough to lead to a causal relationship. This paper presents two main overall sets of data. The first is in regards to the molecular mechanisms of secondary resistance to anti-EGFR therapies, while the second set attempts to determine clinically if KRAS mutations or amplifications are related to acquired cetuximab resistance. For this blog post, I will examine one part of the first data set.

Measles Virus Provides New Hope for Development of Cancer Vaccine

In lecture we learned about the use of vaccines as a preventative measure for cancer, but what if a vaccine could be used to cure cancer? Results from a recent phase 1 trial suggest that this may be a real possibility. After intravenously injecting myeloma patients with the MV-NIS, a genetically engineered measles virus, researchers observed them reach a state of complete remission.

Sunscreen and Skin Cancer: Avobenzone Optimization

To conclude the Sunscreen & Skin Cancer blog series, I am going to tie up some loose strings by discussing the role of the avobenzone sunscreen active in commercial formulations and methods used in order to optimize its ability to attenuate UVR.

Dental X-rays and Thyroid Cancer

In my first blog, I talked about the increased risk of thyroid cancer from childhood therapeutic radiation. This therapeutic radiation was used for acne treatment, lymphoma, Hodgkin’s, and tonsil cancers. I mentioned however that since the 1950’s, therapeutic radiation has only been used in children in cases of morbidity and mortality. But if these therapeutic radiations have decreased, why is the incidence increasing?

Hypomethylating Agents in AML Treatment

A major determinant of chemotherapeutic treatment is whether a patient’s risks of severe side effects would outweigh their benefit from the therapy. In this post, I will look into how the effectiveness of hypomethylating agents in Acute Myeloid Leukemia compares to their promise, especially in older patients who have lower rates of survival and are more susceptible to side effects of treatment. Often these patients do not receive any form of intensive treatment, since the toxicity is not worth the cancerous cell death. The standard AML treatment of high doses of cytarabine, an antimetabolite which inhibits DNA synthesis during the S phase of mitosis, also damages healthy cells with its high toxicity. The American Cancer Society reports the average AML patient age as 66 years old, so the majority of patients with this type of leukemia would not be ideal recipients of the standard-of-care treatment (1).

New Prostate Cancer Screenig Method

Introduction
This research article focused on variances in the levels of different microRNAs (miRNAs) in both the blood and urine of patients with prostate cancer, some of which were metastatic. First off, it is necessary to understand what miRNAs are. They are very short, non-coding, sections of RNA that bind to complementary mRNAs and alter gene expression. So far, about 1,000 miRNAs have been discovered, and each of these is capable in altering the gene expression of up to 1,000 genes. The hypothesis of this research team was that differences in the levels of circulating miRNAs in blood and urine could be correlated to prostate cancer. Furthermore, they also believed that they could predict if the cancer was metastatic or not.

Are all Thyroid Cancers the same?

Throughout all the posts Analisa and I have been doing it has become apparent that when talking about thyroid cancer not all are the same.  There is Papillary carcinoma, Follicular carcinoma, and Sporadic and Familial Medullary Thyroid carcinoma, although some occur more often than others (the three being a rare form of thyroid cancer.) So why do we care?  Before I answer I will explain the differences in all of them as provided by the American Cancer Institute1.  

"An Apple a Day" No Longer

       We all know the age-old saying, "an apple a day keeps the doctor away." A 1997 report, Food, Nutrition, and the Prevention of Cancer: a Global Perspective by the World Cancer Research Fund and American Institute for Cancer Research, supported this adage, declaring "convincing" evidence that "diets containing substantial and varied amounts of vegetables and fruits will prevent 20 percent or more of cancers." For 10 years, this report existed as the most authoritative and influential source in the field. Since the publication, both interest research on the topic has grown rapidly. A second report in 2007, Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective, by the same foundations, reviewed all the relevant research concerning food, nutrition, and cancer prevention.

A new mechanism of Herceptin resistance?

For the Cancer Project, Michael Allen and I are studying HER2 breast cancer.  As we all know from class, trastuzumab, or Herceptin, is one of the monoclonal antibodies able to treat HER2 breast cancer. However, patients treated with Herceptin soon become resistant. As a result, elucidating mechanisms of Herceptin resistance is extremely important. The paper that we are focusing on proposes that a ligand, Autocrine Motility Factor (AMF), somehow induces HER2 phosphorylation and resistance to Herceptin.  This past summer, I actually was able to perform some of these experiments myself and determine whether or not these results were repeatable.

Relatively Indolent But Relentless

If you're interested in something a little different, check out a nice little article in the Atlantic.com about Matt Freedman and his illustrated journal of life during cancer therapy. Relatively Indolent but Relentless was just published last month (Seven Stories Press) and appears to be an unvarnished account of what it's like to go through cancer (radiation) treatment.

Pragmatic Complementary Therapy for Breast Cancer

     In examining the complementary therapy of exercise for breast cancer patients I was struck by a pressing question concerning the pragmatism of this therapy in comparison to what is currently available. Especially, since the incidence of breast cancer is continuing to increase and in 2008 alone it affected 1 million women globally. It is worth considering exercise as a complementary therapy that may be a more cost effective means in providing treatment for breast cancer patients.

Analysis of CTC Concentration in Blood

As my partner had illustrated in his own blogpost, there is believed to be a negative correlation between CTC count and the severity of cancer. The study of CTCs is relatively new and there is a lack of general consensus on what dangerous levels of CTCs actually are. Therefore, most studies determine a concentration of CTCs in the blood at which the patients are believed to be at risk. This is accomplished through a series of tests in which the experimenters take a series of CTC concentrations that they believe to be relevant and note at which concentration the hazard ratio appears to significantly increase. A hazard ratio is a description of the relative risk of a complication occurring with or without a specific event. In CTC studies the event would refer to CTC concentration while the complication could be death or cancer progression. However, the identity of these variables is the choice of the researchers. Once a CTC concentration is determined to be related to a relevant change in hazard ratio, it is labeled as the cutoff value. This cutoff value is then used to mark the change between high and low CTC counts.

Sunitinib Malate as a Second-Line Therapy for Metastatic GIST

        The primary therapy for GIST is surgery, but for cases that are metastatic or unresectable, a tyrosine kinase inhibitor alone or in addition to surgery is the next option. Imatinib mesylate, or Gleevec, is usually the drug given to GIST patients, but as Shiona previously discussed, about 15% of patients with GIST exhibit primary resistance or intolerance to Imatinib. A therapy option available to these patients is Sunitinib malate(Sutent), a multi-targeted tyrosine kinase inhibitor.

Metformin: Decreasing mRNA Expression of Proteins Vital to Pancreatic Cancer

            For my final post I wanted to focus on the topic that our cancer project centers around: the use of the anti-diabetic drug metformin as a potential chemopreventative for pancreatic cancer. Many papers, including the paper I have chosen to analyze, focus on the link between pancreatic cancer (PC) and diabetes mellitus. It is because of this link that researchers believe the answer to decreasing the vast number of new cases of PC developing in the world is in a drug used to treat diabetes mellitus. Pancreatic cancer, with the most common type being pancreatic ductal adenocarcinoma (PDAC), is characterized by uncontrolled cell growth in the tissues of the pancreas (Ref. 1). According to various epidemiologic studies, there is an increased risk of developing PC associated with diabetes mellitus (Ref. 2). Diabetes mellitus is characterized by an abnormality in the body’s ability to either produce or use insulin efficiently, known as insulin resistance (Ref. 1). Both of these situations result in chronic hyperglycemia in the blood stream. PC is one of the deadliest forms of cancer with more than 38,460 deaths in a single year (of the 42,220 total new cases) (Ref. 2). There is a desperate need for a preventative drug or an effective treatment to inhibit the cell cycles in tumor cells or prevent the hyperactivation of certain pathways.

Fragment-Based Lead Discovery

After doing some browsing regarding my cancer project, I came across a chemotherapeutic drug used to treat late stage malignant melanoma called Vemurafenib.  This particular targeted drug therapy was found through fragment-based lead discovery.  I had no idea what this drug discovery method entailed.  Fragment-based lead discovery is a new approach developed this decade that is increasingly used in the pharmaceutical industry. 

Promising new drug dabrafenib has accelerated FDA approval for treatment of metastatic melanoma

In my last blog post I talked about how the project of genome sequencing led to the discovery that a mutation in the BRAF gene causes most metastatic melanomas.  This discovery was predicted to have a promising future in drug discovery that targeted this gene, which proved to be true.

            The most common mutation found in 80-90% of B-Raf mutant cancers is the B-RafV600E mutation.  This mutations substitutes valine with glutamic acid at amino acid 600, which mimics phosphorylation used to regulate growth activity.  The mutation leads to a 500-fold increase in activity of the protein compared to wild-type B-Raf, ultimately showing an oncogenic addiction in the MAPK signaling pathway.  This leads to tumor growth.

Delving further into circulating tumor cell counting accuracy

In my last blog post, I gave a brief introduction and my own analysis of one study done with circulating tumor cell (CTC), emphasizing some of the topics that we covered earlier in this quarter. This week, I focused on a study described by another paper with particular focus on the variables that may render analysis of circulating tumor cells ineffective as a predictor for reactions experienced by cancer patients. There were also some inconsistencies that I noticed between this study and the one I analyzed in my last post and I will be addressing these differences later in this post.

Breastfeeding as a potential risk reduction factor for Breast Cancer

After spending a week discussing cancer prevention, I became incredibly interested in the role of lifestyle choice in cancer development. Though we discussed this briefly, our everyday nutrition, exercise, and routine choices are proving to play an integral role in our individual overall health, including decreasing our risk for developing cancer. And as one of the leading subsets of cancer incidence among women, breast carcinomas have become a highly researched and dissected cancer; in the year 2010 alone about 1.5 million people worldwide were diagnosed. Thus, more individuals have become concerned with lifestyle-oriented health, looking specifically at the modifiable factors in breast cancer prevention. 

Interactions between DNMT3A and other AML-related genes and treatment options

What other genes interact with DNMT3A that complicate the prognosis of AML?

Although in my previous posts, I have focused exclusively on the DNMT3A mutation and its mechanism in AML, clinical practitioners focus on multitude of other recurring genes and abnormalities that are overexpressed in AML patient genomes to aid in prognosis at initial diagnosis. Among such molecular markers are mutations in FLT3, NPM1 (which I have mentioned in my previous discussions of DNMT3A), and c-KIT. My goal is not to provide an exhaustive discussion about the involvement of these genes in the disease as they deserve entirely separate discussions of their own, but to provide a brief overview of them, as it turns out creating future therapies will need to target them as well. 

FLT3 is a receptor tyrosine kinase that spans the plasma membrane and has an important role in proliferation, survival and differentiation of hematopoietic progenitor cells. The incidence of this mutation in AML patients is about 25%, although this varies depending on age, clinical risk, and is more common in adult AML instead of pediatric AML and  myelodysplastic syndrome (MDS), which is a related malignancy that can give rise to AML. It was noted in this paper that several FLT3 inhibitors are currently in various stages of development.

The Biochemical Mechanism Behind Paradoxical Activation in BRAF Wild-type Cells by BRAFV600E inhibitors

In my last two blog posts I wrote about a unique case in cancer therapeutics where the successful treatment for a BRAF^V600E metastatic melanoma with the vemurafenib BRAF inhibitor drug caused the development of chronic myelomoncytic leukemia in the same patient with a preexisting KRAS^G12D mutation.  It was shown through in vitro assays that the Map Kinase pathway was being turned on in KRAS mutant and BRAF wild-type cells causing uncontrollable cellular proliferation.

A Measles Vaccine Kills Cancer?

     They hook you up and then, five minutes into the hour-long process, you get a terrible headache. Two hours later, you start shaking and vomiting and your temperature hits 105 degrees. That doesn't sound like too much fun. But what if this was all you had to endure in order to get rid of your cancer?

   

Notch's Oncogene Role in T Cell Leukemia

Dual role of Notch signaling in cancer    

The table above originates from a review article titled, Oncogenic and Tumor suppressor functions ofNotch in cancer: It’s NOTCH what you think, which was published in The Journal of Experimental Medicine. This table is essentially the overall theme of our Cancer project showing how the role of the Notch signaling pathway can play both the role of an oncogene and the role of a tumor suppressor gene, depending on the type of cancer.3

Cholesterol and its promotion of ER positive breast cancer

For our project, Matt Perez and I are looking into the effects that cholesterol has on ER positive breast cancer.  This article has made this connection, illustrating that increased levels of cholesterol can work to promote tumor growth and hurt the survivability of the patient.  However, it is not cholesterol itself that is the culprit.  It is a primary cholesterol metabolite (Figure 1) called 27-hydroxycholesterol (27HC) which works to promote estrogen receptor (ER) positive tumor growth.  The figure below illustrates the cholesterol metabolic process and the similarities between Estrogen and 27HC, both tumor promoters.  The fact that Estrogen and 27HC are both products of the cholesterol metabolic process provides some reasoning as to why 27HC shows ER agonist activity, that is the ability to bind to a estrogen receptor and mimic its activity, causing for the promotion of tumor growth.

Is There A Protective Role of Tea Against Cancer?

Background:
Everyone loves a nice warm cup of tea when they are sick or feeling worn out. Throughout the years tea has seemed to have a soothing effect on people and has become associated with making people recover faster from the cold or flu. But what if tea is way more important than that; what if tea could keep you from getting cancer!? According to Lambert and Chung, there is a component in green tea called catechins that may aid in many cancer preventive functions such as inhibiting growth factor signaling, promoting apoptosis, and inhibiting protein kinases from functioning. Catechins are defined as a polyphenol compound from the plant Camellia sinensis and have been thought to have antioxidant properties. I am aiming to analyze this claim and get a better idea about how much of a preventative effect tea really has.

Cancer Miracles--Surviving Certain Death through Spontaneous Tumor Regression

Imagine finding a small lump on your body one day that causes pain like nothing you’ve ever felt before. Imagine that upon discovering this lump and visiting the doctor, the physician confirms that you have cancer. What’s worse is that it is inoperable and doctors say there is nothing they can do. The doctor then says you have a month (or even less) to live. Now imagine this: one day, all the pain goes away and a resulting trip to the doctor reveals no sign of cancer, and there are no signs of cancer in the years to come. Sounds hard to believe, right?

Therapeutic Panitumumab-FOLFOX4 intervention with KRAS exon 2 mutation in colorectal cancer.

My partner Tien Lu and I are conducting our cancer project on how mutations in RAS can affect the of anti-epidermal growth factor receptor (EGRF) in colorectal cancer. EGRF is a cell-surface receptor that stimulates protein-tyrosine kinase activity when dimerized. EGRF can activate KRAS, and has been identified as an oncogene. Oncogenes can cause cells selected for apoptosis to survive and proliferate. A RAS mutation can be any KRAS or NRAS mutation in exon 2, 3, or 4. In some instances, it is possible that wildtype RAS allow for antibodies to target EGRF and reduce tumor size in colorectal cancer. Thus, there is the question on how patients with metastatic colorectal cancer with KRAS mutations in exon 2 that are given anti-epidermal growth factor therapy will fare compared to their wildtype counterparts. These mutations can then be used as predictive biomarkers to allow Doctor's to supply more individualized treatment to specific patients. In a clinical trial for the efficacy and safety of Panitumumab conducted by Dr. Douillard of ICO, patients were treated with FOLFOX4 and FOLFOX4 + Panitumumab. Panitumumab, compared to FOLFOX4, is more highly selective for EGRF.

Possible Therapy Targeting the NOTCH1 gene

    As our class has been studying the treatments of cancer and how drugs are developed in the clinical and pre-clincal settings, I have been interested in researching therapy targeted against NOTCH1. While I was doing this, I stumbled upon one article, Notch1 as a Potential Therapeutic Target in Cutaneous T-cell Lymphoma, that researched the possible therapeutic properties of inhibiting the Notch1 pathway (see blog 1 paragraph 2 for simple pathway) in cutaneous T-cell lymphoma.

KRAS Mutations Drive Acquired Resistance to Cetuximab in Colorectal Cancers?

 

          For the cancer project, Ramez Sakkab and I are taking a closer look at colorectal cancer (CRC) therapy. A popular type of therapy is anti-EGFR therapy, targeting the epidermal growth factor receptor (EGFR).  EGFR is a receptor tyrosine kinase that activates KRAS, which eventually leads to the expression of growth-promoting genes. EGFR also activates another pathway that results in protein synthesis, cell growth, survival, and proliferation. The inhibition of EGFR is beneficial for CRC patients, but after an initial response to therapy, some grow to be resistant. The paper that I am interested in investigates this resistance specifically to the drug cetuximab, which binds the extracellular domain of EGFR, preventing ligand binding and interrupting the signal cascade. The authors conclude that mutations of KRAS have a causal relationship with the acquired resistance to anti-EGFR treatment. For this first blog post, I will address my initial thoughts and impressions regarding this paper.

VSV Variants as the "Perfect" Oncolytic Virus?

This post is going to be a continuation from my previous post. I received some very insightful comments challenging me to look further into the use of virus particles and variants as means of ridding the body of cancerous cells. The idea that researchers have been injecting live virus variants into animals, in this case mice, and these variants have been successful at killing off tumor cells is encouraging to the world of cancer research (Ref. 4). However there are a few caveats that even the paper’s authors recognize and explore.

The p53 Gene

            The p53 tumor suppressor gene is responsible for producing the p53 protein, which works to repair the cell when DNA damage is detected. Some of its roles include arresting the cell cycle before replication, inducing apoptosis, or binding to promoter regions to prevent transcription of certain genes. There are about 100 proteins that p53 regulates, and the article I am going to discuss focuses on its relation to skin cancer and regulating UV-induced DNA damage. The article also looks at how p53 can serve as a biological endpoint to evaluate the efficacy of sunscreens in preventing UV-induced skin cancer.