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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