According to the first study conducted under the supervision of scientists at Ohio State University, the drug was first identified 150 years ago and used as a smooth muscle relaxant.
Researchers have found that a drug called papaverine inhibit mitochondrial respiration, the oxygen scavenging components and energy cell and makes the tumor model sensitive to radiation. They found that the drug has no effect on the radiation sensitivity of well-oxygenated normal tissues.
In addition, the researchers showed that papaverine modification of the molecule can improve the safety and molecules may represent a new class of radiation-sensitive drugs that have fewer side effects.
The researchers report their findings in the Proceedings of the National Academy of Sciences. The magazine includes a comment, which states that the study "represents a potential landmark in the six decades of effort to eliminate hypoxia as a cause of the failure of radiation therapy."
"We know that hypoxia limits the effectiveness of radiation therapy, and this is a serious clinical problem, because more than half of all people with cancer receive radiation therapy at some point in their treatment," - said the chief researcher Nicholas Denko, MD, professor of radiation oncology at OSUCCC - James.
"We found that a single dose Papaverina to radiotherapy reduces mitochondrial respiration, reduce hypoxia and significantly enhances the response of tumors to radiation model," - says Denko.
Radiation kills cancer cells in two ways: directly, by destroying DNA and indirectly, by creating reactive, causing damage to molecules called oxygen radicals. Hypoxic conditions reduce the generation of radiation-induced DNA damage and toxicity effective radiation dose.
"If cancer cells in hypoxic areas of tumors during radiation therapy to survive, they can become a source of tumor recurrence," - said Denko. "It is very important that we find ways to overcome this form of treatment resistance."
Cancer cells require high levels of oxygen to stimulate their rapid growth, which can be so great that it is ahead of the delivery of oxygen from the blood supply. Poorly formed blood vessels in tumors when ineffective delivery of oxygen and other nutrients. Insufficient oxygen causes pockets of dead, necrotic cells surrounded by areas of hypoxia. Cancer cells in hypoxic regions away from the blood vessel may also be unavailable for the chemotherapy and be resistant to radiation.
Denko says strategies for overcoming radiation resistance usually focus on delivering more oxygen to the tumor. "But these attempts have reached a small clinical success because the tumor malformed vascular system", - he added. "We took the opposite approach. Instead of trying to increase the supply of oxygen, we have reduced the need for oxygen, and these data suggest that papaverine is a promising and chuvstvitelenym to radiation."