Potentiation of the action of phorbol ester by heparin in human CNE2 cells: Association with enhanced expression of c-jun, p53 and p21 / 中国病理生理杂志

ABSTRACT

AIM: To measure the effect of addition of heparin to TPA on cell proliferation and apoptosis in CNE2 cells and investigate the possible molecular mechanisms underlying heparin and TPA interaction on cell proliferation and apoptosis. METHODS: Cell viability and cell cycle were determined by cell counting and flow cytometry. Apoptosis was evaluated by terminal deoxynucleotidyl transferase-mediated dUPT nick-end labeling (TUNEL) and agarose gel electrophoresis. The expression of c-jun, c-fos, p21 and p53 was examined by Western blot. RESULTS: TPA alone inhibited CNE2 cell proliferation and evoked apoptosis associated with typical morphological changes and DNA fragmentation, which was augmented when heparin was added. Compared with TPA or heparin alone, TPA plus heparin obviously enhanced the number of TUNEL-positive cells from 23%?1.2% to 51%?0.9%. After exposure to different concentrations of heparin (with or without TPA) for 24 h, CNE2 cells were accumulated G 0/G 1 phase. There was a decrease in the number of cells in S phase by the combined heparin and TPA treatment compared to heparin or TPA alone. Western blot analysis revealed that TPA induced the increases in c-jun and p53, p21 protein expression and the levels were remarkably increased following heparin in combination with TPA treatment, whereas no significant change in c-fos was detected. CONCLUSION: These results suggest that heparin synergistically potentiates the action of TPA in CNE2 cells, which may be associated with the increase in c-jun protein level and the upregulation of p21, p53 protein expression.