Epigenomics in breast cancer

In my last post I talked about how empigenomics is a hot topic in understanding how genes get expressed in organismic development and how errant development can lead to disease. Well, here’s a specific case where epigenomics plays a role in a common form of cancer: breast cancer.

An article about research on Physorg.com — my favorite science news site — reports how epigenomics plays a role in breast cancer. The interesting thing is that, to understand it, you have to realize that there’s a kind of cellular double-back-flip involved. Let’s see if I can spell this out.

1. There is a “signaling pathway” called tumor growth factor beta (TGF-beta) that gets over-expressed in some advanced cancers: in this case breast cancer.
2. TGF-beta sustains the activity of an epigenetic molecule called DNA methyl transferase 1 when a cancerous cell divides and produces offspring cells. The combination of the two factors is key to sustaining the progression of the cancer because they block the expression of genes that have been turned off in the process of turning normal cells into cancer cells. In this case the “epigenetic environment” is essential to enabling the cancer promoting process to be passed on to new cancer cells.
3. But if the TGFR-beta can be blocked it causes the methyl transferase — the epigenetic factor — to fade away. With the epigenetic factor reduced the offspring cells re-expresses normal genetics and retard the cancer characteristics.

In my last post on epigenetics I mentioned that epigenetics is ordinarily thought of as passing temporarily acquired factors from one generation of an organism to the next. But epigenetics happens also at the level of cell generations, and acquired, abnormal cancer characteristics need to be passed from one generation to the next for cancer cells to stay cancer cells through several generations as tumors grow.

So there you have it: epigenetics at work in cancer. But all this blocking and unblocking in order for cancer to be sustained opens up the possibility it can be disrupted by a drug and stop the disease.