OTTAWA, Aug. 31 (Xinhuanet) -- Canadian researchers have identified a new gene they say drives tumor growth in breast cancer, a discovery that might lead to a drug therapy with minimalside-effects, it is reported Tuesday.

    The gene in question, beta1-integrin, plays a key role in the formation of embryos. But, in some women, beta1-integrin is hyperactive and can cause breast cancer, one of the researchers explained.

    "This is a fairly important discovery in the field," said Dr. William Muller, of the molecular oncology group at McGill University Health Center in Montreal.

    "We've found a gene that is potentially very critical for tumorinduction in breast cancer but we probably think it has general application to other cancers as well," he said.

    Muller estimated that beta1-integrin indirectly might be responsible for up to 50 percent of breast cancers. Among the other malignancies in which beta1-integrin has been found are prostate, colon and ovarian cancers.

    Researchers from McGill University and McMaster University in Hamilton "knocked out" the gene in more than a dozen breast-cancer-prone mice. First, they showed removal of the gene did not harm normal mammary development of the lab animals. Then they found absence of the gene prevented swelling tumor from growing.

    In their experiments, the researchers conducted biopsies on themice to extract bits of tumor. Using sophisticated recombinant genetic technology, they then knocked the gene out from the biopsied tissue. The findings appear in this month's Cancer Cell journal

    Breast cancer is the most common malignancy in women. It is thesecond-leading cause of female cancer fatalities, after cancer of the lung. Last year in Canada, doctors diagnosed 21,000 cases and5,300 women died of breast cancer. Enditem