Cancer Cell Self-Cannibalism
Cancer research continues to yield exciting breakthroughs as scientists learn more about the molecular and biological activity of cancer cells.
One important new area of research is called autophagy. Haven’t heard of it? You will. Here is a simplified explanation. When cancer cells are mired deep in the core of a tumor, they have limited access to oxygen, growth factors and nutrients from the blood vessels that feed the tumor. So when things get tough for cancer cells, they start eating themselves to get what they need to survive. This is autophagy.
Normal cells rely on autophagy to maintain a balance or during times of stress. Cancer cells do too, not just to survive in the inhospitable environment of a tumor, but also to ward off the effects of chemotherapy and radiation.
When autophagy is activated, (when the “self-cannibalism” begins) it is “an intrinsic cell-survival mechanism that cancer cells turn on to recoup essential building blocks when they’re being poisoned or irradiated,” according to Dr. John Cleveland of The Scripps Research Institute.
Therefore, a greater understanding autophagy’s role in cancer has led researchers to investigate whether blocking autophagy can make cancer treatments more effective, cutting off what amounts to an important escape route.
The research is in early stages and there may be substantial differences in the autophagy activity in different cancer types, or even from tumor to tumor. Still, according to Dr. Ravi Amaravadi from the University of Pennsylvania Abramson Cancer Center, the available evidence suggests that autophagy “seems to be a process that could be important in many cancers.”
A number of clinical trials testing autophagy inhibition are actively recruiting patients with a variety of cancers, including breast, colorectal, myeloma, and chronic lymphocytic leukemia. They are testing an off-patent drug called hydroxychloroquine, or HCQ. The largest trial to date involving HCQ is for patients with newly diagnosed glioblastoma multiforme, a brain cancer. There is also a Phase I/II trial testing authophagy inhibition in patients with stage II or III pancreatic cancer.
The September 7, 2010 issue of the National Cancer Institute Bulletin contains the complete article from which this summary is drawn. To dig deeper, consult the American Society of Clinical Oncology’s work in this area.