Wednesday, May 21, 2014

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.

This would be a huge break if true, a new drug target for HER2 breast cancer? This is the reason why this paper was sent to my principal investigator at my internship. One of the major red flags in the article was the lack of repeats the experimenters ran. The article notes that each experiment was ran at least twice. Does that mean two instances of positive results, then the experiments stop?

Furthermore, the authors of this paper did not seem to prove that AMF acted as a ligand. If AMF was true to act as a ligand, it should show activity relatively instantly. The authors should have ran a time course experiment, in which they add AMF, waited __ amount of seconds, then lyse the cells and prepare for Western Blotting to determine phosphorylation. Another experiment that they should have run was a concentration experiment, in which they add varying amounts of AMF to cells. If the phosphorylation effect due to AMF was dose dependent, there should be increasing levels of phosphorylation with each increased dose.

My next blog post will take a closer look into Autocrine Motility Factor and its functions, hopefully helping to answer the question as to how it acts as a ligand.

Kho, D. H., P. Nangia-Makker, V. Balan, V. Hogan, L. Tait, Y. Wang, and A. Raz. "Autocrine Motility Factor Promotes HER2 Cleavage and Signaling in Breast Cancer Cells." Cancer Research 73.4 (2013): 1411-419. Web.