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March 19, 2005

Yale scientists find microRNA regulates Ras cancer gene

Topics: Medicine

Researchers at Yale University have identified a new way that the Ras gene is regulated in lung cancer.

The oncogene Ras is out of control in about 20 percent of cancers where it is over-expressed or activated by mutation. According to Slack, a member of the Yale Cancer Center, it is one of the most identifiable causes in some forms of lung cancer. His team has identified let-7, a natural and separately transcribed RNA that maps to a chromosomal region associated with lung cancer as a regulator of Ras expression.

DNA of plants and animals contains sequences encoding microRNAs, important regulators of development, that control processes determining cell type and cell death.

"The let-7 microRNA regulates Ras by binding to the message for Ras and likely inhibits translation of the Ras protein," said Slack. "The microRNA does not revert a mutated Ras to normal; instead it acts like a brake on an accelerated Ras."

Lung cancer currently has a poor prognosis with less than 15 percent of patients surviving five years. The lungs, however, are relatively accessible for inhalation of potential gene therapy agents. "While this is not likely to cure the cancer," said Slack, "after diagnosis, gene therapy with let-7 may be a way to alleviate or slow it down."

MicroRNAs (miRNAs) are regulatory RNAs found in multicellular eukaryotes, including humans, where they are implicated in cancer.

Related reading:
RAS Is Regulated by the let-7 MicroRNA Family

Posted by Hyscience at March 19, 2005 9:48 AM



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