From the ddn Blog: A potential double-play on triple negative breast cancer
This column appeared on the ddn Blog on Jan. 21, 2013. Visit the ddn Blog at www.drugdiscoverynews.com/blog.
No matter what kind of cancer you're talking about, metastasis is one of the primary problems, often leading to relapse as the tumors reappear in different parts of the body. And of all the types of cancer out there, breast cancer is one of the worst offenders when it comes to metastasis due to its proximity to the lymph nodes and proclivity to spreading. So far, the best bet for preventing metastasis is the timely removal of tumors and the application of chemotherapy, but now there might be a new method: stopping the metastasis itself.
A research team at Weill Cornell Medical College has discovered a molecular 'switch' that allows triple negative breast cancer cells—which doesn't express the genes for the estrogen receptor, progesterone receptor or HER2/neu—to develop the protrusions necessary to detach from the primary tumor and metastasize throughout the rest of the body. Triple negative breast cancer is one of the deadliest types of breast cancer, with high recurrence rates and metastatic spread, and accounts for 15 to 25 percent of all breast tumors.
The researchers focused on finding agents that could restore function to a microRNA that plays a significant role in the spread of cancer, and found that the miRNA miR-708 is inhibited in triple negative breast cancer. When functioning regularly, miR-708 acts as a metastatic tumor inhibitor, and tumors don't spread or form macrometastases. By delivering a synthetic form of the miRNA in bubbles of fat, the researchers were able to block the cancer cells' metastatic growth in the lungs of mice.
In addition, the team also discovered that polycomb repressor complex proteins are responsible for the inhibition of miR- 708, which offers additional promise since several pharmacological agents currently undergoing testing as lymphoma cancer drugs are designed to inhibit histone-lysine N-methyltransferase EZH2, the member of the polycomb group that directly silences miR-708.
Obviously, no matter what type of cancer is being treated, the hope is always to stop it before it spreads. But in cancers such as triple negative breast cancer and others prone to metastasis, having a way to curtail the spread of cancer is the best kind of backup there is.