Research on the inhibiting effect of tanshinone IIA on colon cancer cell growth via COX-2-Wnt/ß-catenin signaling pathway.

ABSTRACT

PURPOSE: To investigate the effects of tanshinone IIA (TSIIA) on the colon cancer cell growth and to explore the mechanism of TSIIA in regulating the colon cancer cell growth via cyclooxygenase (COX)-2-Wnt/ß-catenin signaling pathway. METHODS: Colon cancer cell line HC8693 was exposed to different concentrations of TSIIA. After 24-hr exposure, MTT assay was used to detect the lethal concentration of TSIIA on HC8693 cells. The expression levels of COX-2 and ß-catenin were detected by semi-quantitative PCR (sq-PCR). The protein expression levels of COX-2 and ß-catenin were detected by Western blot, and the expression of vascular endothelial growth factor (VEGF) was detected by enzyme-linked immunosorbent assay (ELISA). Celecoxib, a COX-2 selective inhibitor, was used to inhibit the COX-2 of HC8693 cells, and the inhibiting effect of TSIIA on HC8693 cell growth was assessed. RESULTS: MTT assay showed that TSIIA concentration of 20µM inhibited significantly the HC8693 cell growth (p<0.01). With reverse transcription after RNA extraction and (sq-PCR) detection the expression levels of COX-2 and ß-catenin were significantly decreased (p<0.01). Western blot showed that the protein expression levels of COX-2 and ß-catenin were significantly decreased (p<0.01). ELISA showed that the expression of VEGF was also significantly decreased (p<0.01); after celecoxib (10µM) was added, 20µM TSIIA had no inhibiting effect on the growth of HC8693 cells (p>0.05). Western blot showed no significant differences in the protein expression levels of COX-2 and ß-catenin compared with those in the control group (not exposed to TSIIA). CONCLUSIONS: TSIIA can inhibit the expression of COX-2 and activate the Wnt/ß-catenin signaling pathway, thus downregulating the level of VEGF, and resulting in growth inhibition of colon cancer cells.