Objective: To investigate the role of cyclin kinase inhibitor p27 on proliferation of mesangial cell (MC) induced by tumor necrosis factor-alpha (TNF-alpha).
Methods: p27 protein of MC lysate was detected with Western blotting analysis. The degree of MC proliferation was estimated through [(3)H] thymidine incorporation. The effect of reducing p27 expression on MC proliferation was analysed with p27 antisense oligodeoxynucleotide (ODN) phosphorothioate.
Results: TNFalpha (200 000 U/L) decreased p27 level to 0.6 +/- 0.1 from 1.1 +/- 0.1 of MC lysate cultured in serum-free DMEM for 24 hours (P < 0.01) and increased [(3)H] thymidine incorporation to 2 060 +/- 112 from 685 +/- 53 cpm/well (P < 0.01). p27 antisense ODN transfection decreased p27 level of MC stimulated by TNF-alpha for 24 hours (0.3 +/- 0.1 vs 0.6 +/- 0.1, P < 0.01) and increased [(3)H] thymidine incorporation (2 420 +/- 130 vs 2 060 +/- 112 cpm/well, P < 0.05) in 24 hours of culture.
Conclusion: The decline of p27 protein may play an important role in MC proliferation induced by TNF-alpha. Because the cell cycle is controlled by the interplay between the positive cell cycle regulatory proteins (CCRP) and negative CCRP, further research is needed to study the expression of the positive and negative CCRP in MC in order to understand better the role of CCRP in MC proliferation.