The metabolism of arachidonic acid (AA) by either the cyclooxygenase (COX) or lipoxygenase (LOX) pathway generates eicosanoids, has been implicated in the pathogenesis of a variety of human diseases, including cancer, and may play important roles in tumor promotion, progression, and metastasis. The involvement of 12-LOX expression and function in tumor growth and metastasis has been reported in both murine and human tumor cell lines. The expression of 12-LOX in human renal cell carcinoma (RCC), normal kidney (NK) tissues and 3 kinds of RCC cell lines (Caki-1, A498, RC-1), and its effects on cell proliferation in 3 RCC cell lines were examined. Expression of 12-LOX protein was detected by immunohistochemistry and 12-LOX mRNA in RCC cell lines was detected by nested RT-PCR. Effects of 12-LOX inhibitor on RCC cell growth was examined by MTT assay, and to determine whether or not 12-LOX inhibitors induce apoptosis, we used Hoechst staining. While 12-LOX expression was detected slightly in NK tissues, a marked expression of 12-LOX was detected in RCC tissues. All human RCC cell lines expressed 12-LOX mRNA. The 12-LOX inhibitor baicalein caused marked inhibition of all three kinds of RCC cells in a concentration- and time-dependent manner. Cells treated with 12-LOX inhibitor showed chromatin condensation, cellular shrinkage, small membrane-bound bodies (apoptotic bodies), and cytoplasmic condensation. These results suggest 12-LOX may play a role in the progression of RCC in human tissue, and its inhibitors may become anticancer agents in human RCC.

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