LONDON (REUTER) - A virus that commonly infects AIDS patients may offer a clue as to how it, and possibly other viruses, causes cancer, U.S. researchers said on Wednesday. Marvin Gershengorn and colleagues at Cornell University's medical school said they showed the virus has a gene that could cause uncontrolled cell
growth - one of the characteristics of cancer. They said their findings could explain the strong association between Kaposi's sarcoma-associated herpes virus (KSHV or HHV 8) and Kaposi's sarcoma skin tumours, one of the markers of AIDS. Gershengorn's group homed in on a protein known as a G-protein-coupled receptor (GPCR), known sometimes to be involved in disease. They found it stimulates cells to reproduce, which means it could cause cells to go into the replicative overdrive that marks cancer. It does this without the help of other chemicals usually required for the process, such as hormones or neurotransmitters. In effect, it can leave a cell permanently "switched on". Gershengorn said the finding could also shed light on associations between other viruses and cancers. Similar genes have been found in cytomegalovirus, which also commonly infects AIDS patients. "If we can show that this is related to disease pathogenesis, we might be able to discover drugs that... turn the receptor off." This would probably include a class of drug known as inverse agonists or negative antagonists. There are strong indications that some viruses can cause cancer. In July, Columbia University researchers found that half of 40 gay AIDS patients who eventually developed Kaposi's were infected with KSHV. Human wart virus, also known as papilloma virus, is strongly associated with cervical cancer. Hepatitis B virus (HBV) is known to lead to liver cancer. Britain's Cancer Research Campaign estimates that viruses may be responsible for as many as 15 percent of all cancers worldwide.