 |
|
Researchers find way to make tumor cells easier to destroy
May 07, 2008Tumors have a unique vulnerability that can be exploited to make them more sensitive to heat and radiation, researchers at Washington University School of Medicine in St. Louis report.
The Washington University radiation oncology researchers found that tumors have a built-in mechanism that protects them from heat (hyperthermia) damage and most likely decreases the benefit of hyperthermia and radiation as a combined therapy.
By interfering with that protection, the researchers have shown that tumor cells grown in culture can be made more sensitive to hyperthermia-enhanced radiation therapy. The findings are reported in the May 1, 2008 issue of Cancer Research.
Radiation therapy is a mainstay of cancer treatment but doesn't always completely control tumors. For several years, raising tumor temperature has been investigated as a radiation therapy enhancer with few adverse side effects.
"Past research has shown that hyperthermia is one of the most potent ways to increase cell-killing by radiation," says senior author Tej K. Pandita, Ph.D., associate professor of radiation oncology and of genetics and a researcher with the Siteman Cancer Center at Washington University School of Medicine and Barnes-Jewish Hospital.
"But now we've found that heat also enhances the activity of an enzyme called telomerase in cancer cells," he says. "Telomerase helps protect the cells from stress-induced damage and allows some of them to survive. We used compounds that inhibit telomerase and showed that cancer cells then become easier to destroy with hyperthermia and radiation used in combination."
Telomerase repairs the ends of chromosomes by maintaining stability of specialized cellular structures called telomeres after cells divide. Without telomerase the number of cell divisions is limited. Telomerase is not active in most normal human cells but is active in most cancer cells, which rely on telomerase to continue to proliferate.
In this study, Pandita's research group found that moderately turning up the heat also turns up the activity of telomerase in tumor cells. The researchers found that if they inactivated telomerase and then increased the temperature of tumor cells, more cells were killed by ionizing radiation. Because nearly all cancers have telomerase, drugs that turn off its activity could be useful against many cancers.
The researchers tested three compounds, and one, GRN163L, more strongly inhibited telomerase than the others. Many groups are studying GRN163L as an anticancer therapeutic, and it recently received clearance by the U.S. Food and Drug Administration to enter human phase I/II clinical testing in chronic lymphocytic leukemia. In some preliminary studies, GRN163L has been shown to be additive when used in combination with existing cancer drugs or radiation.
Next, Pandita and colleagues will test the effect of GRN163L on tumors in mice to see if it will enhance the cell-killing effect of hyperthermia and radiation. They are also working to develop chemicals that have heat-like effects to bypass the need to supply a physical heat source to tissue.
Washington University School of Medicine
Radiation therapy is a mainstay of cancer treatment but doesn't always completely control tumors. For several years, raising tumor temperature has been investigated as a radiation therapy enhancer with few adverse side effects.
"Past research has shown that hyperthermia is one of the most potent ways to increase cell-killing by radiation," says senior author Tej K. Pandita, Ph.D., associate professor of radiation oncology and of genetics and a researcher with the Siteman Cancer Center at Washington University School of Medicine and Barnes-Jewish Hospital.
"But now we've found that heat also enhances the activity of an enzyme called telomerase in cancer cells," he says. "Telomerase helps protect the cells from stress-induced damage and allows some of them to survive. We used compounds that inhibit telomerase and showed that cancer cells then become easier to destroy with hyperthermia and radiation used in combination."
Telomerase repairs the ends of chromosomes by maintaining stability of specialized cellular structures called telomeres after cells divide. Without telomerase the number of cell divisions is limited. Telomerase is not active in most normal human cells but is active in most cancer cells, which rely on telomerase to continue to proliferate.
In this study, Pandita's research group found that moderately turning up the heat also turns up the activity of telomerase in tumor cells. The researchers found that if they inactivated telomerase and then increased the temperature of tumor cells, more cells were killed by ionizing radiation. Because nearly all cancers have telomerase, drugs that turn off its activity could be useful against many cancers.
The researchers tested three compounds, and one, GRN163L, more strongly inhibited telomerase than the others. Many groups are studying GRN163L as an anticancer therapeutic, and it recently received clearance by the U.S. Food and Drug Administration to enter human phase I/II clinical testing in chronic lymphocytic leukemia. In some preliminary studies, GRN163L has been shown to be additive when used in combination with existing cancer drugs or radiation.
Next, Pandita and colleagues will test the effect of GRN163L on tumors in mice to see if it will enhance the cell-killing effect of hyperthermia and radiation. They are also working to develop chemicals that have heat-like effects to bypass the need to supply a physical heat source to tissue.
Washington University School of Medicine
Tumor Cells News and Current Tumor Cells Events RSSVitamin C injections slow tumor growth in mice
High-dose injections of vitamin C, also known as ascorbate or ascorbic acid, reduced tumor weight and growth rate by about 50 percent in mouse models of brain, ovarian, and pancreatic cancers, researchers from the National Institutes of Health (NIH) report in the August 5, 2008, issue of the Proceedings of the National Academy of Sciences.
Nanoparticles + light = dead tumor cells
Medical physicists at the University of Virginia have created a novel way to kill tumor cells using nanoparticles and light.
A new cellular pathway linked to cancer is identified by NYU researchers
In the life of a cell, the response to DNA damage determines whether the cell is fated to pause and repair itself, commit suicide, or grow uncontrollably, a route leading to cancer.
Vitamin A pushes breast cancer to form blood vessel cells
Researchers at Georgetown University Medical Center have discovered that vitamin A, when applied to breast cancer cells, turns on genes that can push stem cells embedded in a tumor to morph into endothelial cells. These cells can then build blood vessels to link up to the body's blood supply, promoting further tumor growth.
Counting tumor cells in blood predicts treatment benefit in prostate cancer
Counting the number of tumor cells circulating in the bloodstream of patients with castration-resistant prostate cancer can accurately predict how well they are responding to treatment, new results show.
Blue light used to harden tooth fillings stunts tumor growth
A blue curing light used to harden dental fillings also may stunt tumor growth, Medical College of Georgia researchers say.
Refusal of suicide order: Why tumor cells become resistant
Cells with irreparable DNA damage normally induce programmed cell death, or apoptosis. However, this mechanism often fails in tumor cells so that transformed cells are able to multiply and spread throughout the body.
New Cancer Treatment Targets Both Tumor Cells and Blood Vessels
It takes more than one punch to fight tumors. Often, tumors have more than one way of surviving, and attacking the tumor alone is not enough.
Experimental anti-cancer synthetic molecule targets tumor cell growth and angiogenesis
A recent study conducted by three French CNRS (Centre National de la Recherche Scientifique) laboratories describes a new candidate anti-cancer drug, named HB-19.
Weight loss after gastric bypass surgery may protect against infection and cancer
Another health benefit of bariatric weight-loss surgery may be a heightened immune defense against cancer and infections, a new study suggests. The results will be presented at The Endocrine Society's 90th Annual Meeting in San Francisco.
More Tumor Cells News Articles
| © 2008 BrightSurf.com |