Protein May Have a Role Supporting Cancer Cells

Study in mouse and human cancer cells suggests the STAT3 protein may mediate tumor growth

TUESDAY, June 30 (HealthDay News) -- A protein previously thought only to regulate gene expression in the cell nucleus during an immune response, also exists in the cell mitochondria where it may play a fundamental role converting normal cells to cancer cells, according to a study in the June 26 issue of Science.

Daniel J. Gough, Ph.D., of the New York University School of Medicine, and colleagues studied the Signal Transducers and Activators of Transcription 3 (STAT3) protein to assess its role in converting normal cells to cancer cells. Using mouse tumors and human cancer cell lines, the researchers removed the STAT3 protein and cultured the cells. They also tested the cells for the presence of STAT3 in different sites outside of the nucleus in the cell cytoplasm.

The researchers found that in the absence of STAT3, culture cell growth was impaired, and by restoring STAT3 cell growth also was restored. They also found that in addition to being present in the cell nucleus, STAT3 was present in mitochondria where it may regulate the activity of the electron transport chain in tumors cells.

"Therefore, the metabolic shift important for tumor growth mediated by mitochondrial STAT3 may reflect exploitation of a normal function. If so, mitochondrial STAT3 function could provide an attractive target for therapeutic approaches to cancer," the authors write.

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