Ovarian Cancer Research Today is a free monthly online journal that collates and summarizes the latest research about Ovarian Cancer, including details on symptoms, causes, treatment, information. | ||||||||
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Loss of TNF-alpha-regulated COX-2 expression in ovarian cancer cells.Yang WL, Roland IH, Godwin AK, Xu XX Ovarian Cancer and Tumor Cell Biology Programs, Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111, USA. Cyclooxygenase 2 (COX-2) is often found overexpressed in cancer and is thought to have a role in carcinogenic promotion, and thus is a target for therapeutic intervention. Here, we investigated the regulation of COX-2 expression in normal and cancer ovarian surface epithelial cells. Tumor necrosis factor alpha (TNF-alpha) is a potent inducer of COX-2 expression in the ovarian surface epithelium and this regulation is a critical step in ovulation. We observed that TNF-alpha stimulated COX-2 expression in human primary and immortalized epithelial (HIO) cell lines. The stimulation was suppressed by inhibitors of several signaling pathways, indicating the collaboration of TNF-alpha-activated signaling pathways mediates the regulation of COX-2 expression. In five ovarian cancer cell lines analysed, four did not express detectable COX-2 and TNF-alpha failed to elicit COX-2 expression. In NIH:OVCAR-5, the only ovarian cancer cell line expressing COX-2, signal pathway inhibitors no longer affected TNF-alpha-induced COX-2 expression. Thus, we conclude that TNF-alpha mediated signaling is uncoupled from the modulation of COX-2 expression in ovarian cancer. The loss of COX-2 expression was also observed to associate closely with epithelial neoplastic morphological transformation. The frequent loss of COX-2 expression suggests in ovarian cancer, unlike in other epithelial cancers, COX-2 expression does not contribute to ovarian cancer malignancy. Published 2 December 2005 in Oncogene, 24(54): 7991-8002.
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