Marijuana short tumor growth of lung cancer in half, study shows

The active ingredient in marijuana cuts tumor growth in common lung cancer in half and significantly reduces the ability of cancer to spread, said researchers at Harvard University who tested the chemical in laboratory studies and mouse. They say that this is the first experiments to demonstrate that the compound, Delta-tetrahydrocannabinol (THC), inhibits growth and migration-induced EGF receptor in epidermal growth factor (EGFR) expressing non-small cell varieties lung cancer cells. Lung cancers that over-express EGFR are usually highly aggressive and resistant to chemotherapy. THC that targets receptors CB1 and CB2 of cannabina is similar in function to endocannabinoids, which are cannabinoids that occur naturally in the body and activate these receptors. The researchers suggest that THC or other designer agents that activate these receptors might be used in a targeted way to treat lung cancer. "The beauty of this study is that we are showing that a substance of abuse, if used prudently, may offer a new road to therapy against lung cancer," said Anju Preet, Ph.D., a researcher in the division of medicine experimental. Acting through receptors CB1 and CB2 of cannabina, the endocannabinoids (as well as THC) are thought to play a role in variety of biological functions, including control of pain and anxiety, and inflammation. Although a medical derivative of THC, known as Marinol, has been approved for use as an appetite stimulant for cancer patients, and a small number of states in the U.S. allow medical use of marijuana to treat the same side effect, few studies have shown that THC might have antitumores activity, Preet says. The only clinical trial testing THC as a treatment against cancer growth was a recently completed British pilot study in human glioblastoma. In the current study, researchers first showed that two varieties of cells in the lung cancer patients and tumor samples express CB1 and CB2 lung and non-toxic doses of THC inhibited growth and expansion in the variety of cells . "When cells are pretreated with THC, they have less EGFR stimulated invasion as measured by the number of unsta vitro analysis," Preet said. So, for three weeks, researchers injected standard doses of THC into mice that had been implanted with human lung cancer cells, and found that tumors were reduced in size and weight by nearly 50 percent in animals treated compared to a control group. There were also about a 60 percent reduction in cancer lesions in the lungs in these mice and a significant reduction in protein markers associated with cancer progression, Preet says. Although researchers do not know why THC inhibits tumor growth, say the substance could be activating molecules that arrest the cell cycle. They speculate that THC may also interfere with angiogenesis and vascularization, which promotes growth of cancer. Preet says much work is necessary to clarify the path by which THC functions, and cautions that some animal studies have shown that THC can stimulate some cancers. "THC offers some promise, but we have much to do before we know what their potential," she said.
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