Molecular mechanism of cross-talk between signal transducer and activator of transcription 3 and perioxisome proliferators-activated receptor 5 signaling pathway in regulating proliferation of colon cancer cells

Objective To investigate the role of selective COX-2 inhibitor NS398 on proliferation and apoptosis of colorectal cancer, and to reveal the COX-2-independent mechanism of NS-398 on colorec-tal cancer cell. Methods RT-PCR analysis was performed on human colon cancer cell line SW480 to detect the COX-2 mRNA expression. After addition of NS-398 (a selective COX-2 inhibitor) into culture medium, MTT assay was used to measure the absorption value and the growth curve was drawn. Western blot analysis was performed on colon cancer cell lines; Flow cytometry was applied to analyze the cell cycle and apoptosis. Results The expression of COX-2 mRNA was not detectable in SW480 colon cancer cells. NS-398 (75 μmol/L) inhibited the cells proliferation and induced apoptosis in colon cancer cell lines. The ratio of cells in G1 phase was increased from 37.9% to 48.6 % , and the ratio of cells in S phase was decreased from 58.1% to 44.9%. NS398 also diminished the expression of Stat3, PP ARδ, cyclin D1 and bcl-xL. Conclusion The selective COX-2 inhibitor NS-398 may inhibit the proliferation and induce apoptosis of colon cancer cell lines by blocking specific signaling pathway.