RESUMO
Protein Kinase C which is a Ca++ -activated, phospholipid - dependent enzyme phosphorylates numerous protein substrates and participates in intracellular signaling processes. Protein kinase C is associated with a wide range of biological effects including stimulus-secretion coupling, induction of cellular proliferation and differentiation, activation of nuclear transcription factors and cell surface receptors and tumor promotion. Programmed cell death, referred to apoptosis is an active, energy-dependent process in which the cell participates in its own destruction during apoptosis. There is condensation and fragmentation of nuclear chromatin, accompanied by a marked decline in total cell volume, dilation of the endoplasmic reticulum and general compacting of cellular organelles. Thereafter, there is fragmentation of both nucleus and cytoplasm to give rise to small membrane-bound vesicles known as apoptotic bodies. Protein kinase C may have the regulatory role in apoptosis. Staurosporine is a potent protein kinase C inhibitor. Staurosporine inhibited the growth of human invasive bladder tumor cells, T24 in MTT test. The survival fractions of human invasive bladder tumor cells T24 were 100.0%, 76.0%, 62.5% and 18.1% with staurosporine concentration 0nM, 10nM, 100nM and 1000nM, respectively. From the results we identified that staurosporine inhibited the growth of T24 cells markedly in a dose dependent manner(P<0.05). 12-hour exposure of T24 cells to staurosporine failed to induce DNA fragmentation at the concentrations of 0nM, 10nM and 100nM but promoted fragmentation at the concentration of 1000nM, showing typical ladder pattern on agarose gel electrophoresis. On the examination of cellular morphology, T24 cells showed the features of apoptosis such as cell shrinkage, nuclear condensation and formation of bleb and apoptotic bodies after exposure to staurosporine of 10nM, 100nM and 1000nM concentrations. These results suggest that staurosporine have remarkable cytotoxic effect against human invasive bladder tumor cells T 24 and the mechanism of cytotoxicity may be apoptosis.