MicroRNA linked to oncogene

A Yale scientist has identified a microRNA, let-7, that controls an oncogene implicated in about 20 percent of cancers, including lung cancer. The finding, reported in March in the journals Cell and Developmental Cell, presents new possibilities for diagnosis and treatment, according to Frank J. Slack, Ph.D., assistant professor of molecular, cellular and developmental biology.

Oncogenes are segments of DNA that can induce uncontrolled cell growth and, ultimately, the formation of cancerous tumors. MicroRNAs regulate gene expression. Let-7, said Slack, stops the oncogene known as Ras from producing the Ras protein. In the absence of let-7 RNA, cells in the nematode C. elegans continued to divide instead of differentiating normally. Let-7 in humans, Slack said, is almost identical to the worm sequence.

Lung cancer has a poor prognosis, said Slack, “but gene therapy with let-7 may be a way to alleviate it or slow it down.”