Thursday, April 28, 2011

Sleeping Cancer Cells

Slept as soundly as a ... cancer cell?
In certain cases, a malignant and cancerous tumor can be surgically removed from a patient, yet the cancer will return after the malignancy has been removed from the body. We might suspect that this new malignancy is a result of incomplete excision, that not all of the original tumor was removed, or maybe that the tumor was able to metastasize and proliferate before the surgery. However, we must appreciate that this is very unusual for cancer cells to remain in the body, not multiplying, for such a prolonged period of time; the disease is characterized by its ability to proliferate quickly and efficiently. Though we might assume that this reoccurred is the result of slow growing tumors, this is not the case; many cases are reported where the original tumor (before excision) grew very rapidly. Scientists realized that cancer cells must have the ability to lie dormant for a period of time, and reactive into fully functioning cancer cells. These secondary tumors are typically drug resistant (because many drug therapies target rapidly dividing cells, and these cells are not yet dividing) and are the result of metastasis. In my opinion, the most interesting part about this idea of "sleeping," or dormant cancer cells, is that they sustain life in various tissues for a sustained period of time, without multiplying, yet they retain the capacity to begin multiplying and behave (once again) like a cancer cell.

Though dormant cancer cells were discovered long ago (the article that led me to this topic was published in 1954), little is known about how or why cancer cells were able to preform this function, and scientists have searched for mechanisms to describe this phenomenon for years. Research in 2009 came from Dr. Robert Bast that led to the discovery that dormant cancer cells actually rely upon self cannibalization in order to survive - yes, they eat themselves! This typically causes cancer cell death, but in the case of dormant cancer cells, it can help them avoid starvation.
Alternative research by Dr. Dalit Barkan has indicated a way in which dormant cancer cells reactivate. His research involves the way in which cells are able to "turn on" and "turn off" cell division in mitosis, and believes this ability is strongly related to interactions with the cells extra cellular matrix, or ECM.
Most recently, Dr. Sridhar Ramaswamy, of Mass. General Hospital, has been developing new ways of understanding this process, and as of April 4, 2011, he received a grant in order to further his research. In the future, Dr. Ramaswamy hopes to discover exactly how these cancer cells "go to sleep," and understand the mechanism that allows them to remain dormant and "wake up." Through this understanding, the doctor hopes to then discover ways to either prevent these cells from going to sleep or waking up, or to find a way to specifically target and kill these sleeping cancer cells. Though the actual understanding of how Ramaswamy and his group plan on achieving this is outside my scope of understanding, I believe it involves intensive research on the genetic level.