Possible cancer inhibitor found in worm study

Yale scientists studying the microscopic worm C. elegans have discovered a cellular brake on a gene implicated in about 20 percent of human cancers, especially lung cancer. The finding opens up new possibilities for cancer diagnosis and treatment, says Frank J. Slack, Ph.D., assistant professor of molecular, cellular and developmental biology.

Slack and his colleagues found that a snippet of genetic material in the worms called let-7 shuts down the activity of Ras, an “oncogene” that can cause cell proliferation to spiral out of control, as happens in cancer. In Slack’s experiment, in developing worms that lacked let-7, cells continued to divide instead of differentiating.

Scientists use C. elegans in the laboratory because the worm shares many genes with more complicated animals. According to Slack, let-7 and Ras are almost identical in humans and C. elegans, and Ras protein, the product of the oncogene, is abundant in human lung cancers.

Lung cancer has a poor prognosis, but the lungs may be an ideal target for inhalable gene therapy agents. This may not cure the cancer, Slack said, but “gene therapy with let-7 may be a way to alleviate it or slow it down.”