'Master switch' of cancer
The process by which cancer cells grow new blood vessels to sustain themselves can be prevented.
A new study has discovered why cancer survives even after radiation and how angiogenesis, the process by which cancer cells grow new blood vessels to nourish and sustain themselves, can be prevented.
The research conducted by Radiation biologists at the Duke Comprehensive Cancer Center has identified the "master switch" that cancer cells use to dispatch protective messages to nearby blood vessels, fortifying the vessels against deadly onslaughts of radiation.
According to them it is a protein called "Hypoxia Inducible Factor" (HIF-1) which turns on production of these protective messages.
"HIF-1 is the switch inside cancer cells that gets turned on by radiation therapy. Once it is activated, HIF-1 then triggers the production of well-known growth factors such as VEGF and bFGF, as well as more than forty different protein signals that regulate tumour metabolism, metastasis and angiogenesis," explains Dr Mark Dewhirst, Ph.D., DVM, professor of radiation oncology at Duke and principal investigator of the study.
The researchers suppressed HIF-1 with experimental drugs given together with radiation therapy in animals with cancer. In doing so, they successfully inhibited blood vessel growth in tumours and, thereby, the growth of tumours themselves. They are now hoping to test this potential new therapy plus radiation in humans.
"We're employing a treatment strategy where we accomplish two hits -- killing the cancer cells with radiation and blocking their blood vessel survival with an anti-HIF drug. By pinpointing and blocking the source of all the signals, we have successfully halted the cancerous blood vessel growth in animals without harming normal blood vessels," said Benjamin Moeller, a graduate student in the Duke M.D./Ph.D. program.
Approximately half of all cancer patients in the U.S. are treated with radiation therapy. However, the success of therapy depends largely on how sensitive a tumor's blood vessels are to radiation. If blood vessels in the tumor survive after radiation, they can provide nutrients to the surviving cancer cells to begin rebuilding the tumor.
The study which is published in the May, 2004, issue of Cancer Cell, says that knowing how HIF-1 works inside cancer cells will be critical to manipulating its behavior and making its blood vessels more responsive to radiation.