Public Release: 

Retrovirus Transforms Normal Animal Cells Into Cancer Cells, Finds University of Pittsburgh Cancer Institute Researchers

University of Pittsburgh Medical Center

San Diego, April 10 -- A retrovirus that was isolated from mouse melanomas can transform normal mouse melanocytes into melanoma cells, according to research being presented by UPCI scientists on April 16 at the annual meeting of the American Association for Cancer Research. "This is the first evidence that a retrovirus can cause the development of melanoma," said Elieser Gorelik, M.D., Ph.D., professor of pathology at the University of Pittsburgh Medical Center. Melanocytes are the skin's pigment-forming cells that become malignantly transformed into life-threatening melanoma, whose underlying causes remain obscure. The incidence of melanoma is increasing more rapidly than any other cancer.

In their study, the researchers grew mouse melanocytes in the laboratory and exposed them to C-type ecotropic retrovirus derived from a mouse melanoma called B16. Infected cells then changed shape and started behaving like melanoma cells.

The melanoma-associated retrovirus belongs to the family of mouse leukemia viruses that has been shown to induce leukemia and lymphoma in mice. These retroviruses do not contain an oncogene, or cancer-causing gene. Thus, the researchers speculate that the melanoma-associated retrovirus inserts itself randomly into a normal melanocyte's genetic material. There, it somehow upsets normal cellular genetic activity, perhaps by triggering the abnormal expression of one of the cell's own oncogenes or by interfering with a cell's tumor suppresser gene, which normally prevents the cell from becoming cancerous. As a result, normal melanocytes might undergo malignant transformation.

The researchers' current goal is to find out which cellular genes the virus is disturbing. "Once we have this information, we can look at human melanomas to determine whether the same cellular genes are also acting incorrectly. These findings can help us understand the molecular mechanisms underlying melanoma in people," remarked Dr. Gorelik.


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