[Effects of sodium orthovanadate on proliferation and apoptosis in raji cells and its mechanism]

In order to investigate the role and the mechanism of protein tyrosine phosphatase (PTPase) signaling pathway in the regulation of proliferation, cell cycle and apoptosis in lymphoma cells, the effects of sodium orthovanadate, Na(3)VO(4), a specific PTPase inhibitor, were explored on Raji lymphoblast-like cell line by MTT assay and CFU-Raji culture, morphologic observation, DNA gel electrophoresis, FCM and RT-PCR. Results showed that MTT assay and CFU-Raji culture demonstrated that sodium or thovanadate inhibited the growth of Raji cells in a concentration-dependent fashion; morphologic observations showed that Raji cells exhibited cytoplasm shrinkage, cytoplasm membrane blebbing, nuclear fragmentation and chromatin condensation forming crescents along nuclear membrane characteristic of apoptosis in the presence of Na(3)VO(4); DNA gel electrophoresis revealed typical DNA ladder reminiscent of DNA cleavage at internucleosomal sites in Na(3)VO(4) treated cells; FCM and RT-PCR indicated that Na(3)VO(4) intervention increased the fraction of annexin V(+) PI(-) cells, reduced the value of mitochondrial transmembrane potential, induced G(2)/M arrest and down-regulated the expression of Bcl-2 and cyclin B1 at both mRNA and protein level in a concentration-dependent manner. It was concluded that PTPase pathway might be implicated in the regulation of cell proliferation, cell cycle and apoptosis, and PTPase specific inhibitor Na(3)VO(4) could induce Raji cell growth inhibition, G(2)/M arrest and apoptosis via down-regulation of Bcl-2 and cyclin B1, and reduction of mitochondrial transmembrane potential.