[Influence of calcineurin on apoptosis of pre-B lymphocytes and the leukemia cells derived from pre-B lymphocytes].

This study was aimed to compare the differential expressions of calcineurin (PP2B, PP3) in the mouse Pre-B cell lines (S9) and the tumor cell lines (S4C2) derived from pre-B lymphocytes, and to clarify its possible mechanism involving in the leukemia cell apoptosis. The quantitative real-time PCR was used to detect the differential expressions of H2AX-associated phosphakinase ATM, ATR, DNA-PKs, JNK1, P38 and the γ-H2AX-related phosphatase PP1, PP2A, calcineurin, PP4, PP6, PP5 between S9 and S4C2 cell lines. CCK-8 assay and flow cytometry were used to detect the effect of imatinib (IM) and cyclosporine A (CsA) on cytotoxicity and apoptosis of 2 cell lines. The Western blot was used to detect the effects of 2 drugs on apoptosis of S9 and S4C2 cell lines. The results showed that the expression level of calcineurin gene in the leukemia cell S4C2 was about 3.5 times of that in S9 cells, while the expression of other genes in these 2 kinds of cells was not significantly different. The apoptosis and toxicity of IM and CsA on S4C2 cells was significantly stronger than that on S9 cells. The expression level of calcineurin in S4C2 cells was higher than that in S9 cells.When CsA inhibited the calcineurin activity, the expression of DNA damage marker γ-H2AX in S9 cells was significantly lower than that in S4C2 cells,while the expression level of γ-H2AX between the two cell lines was no significantly different after treatment with imatinib, the expression level of γ-H2AX in S9 cells was lower than that in S4C2 cells when the two drugs were combined. It is concluded that the calcineurin plays a role of anti-apoptosis in B leukemic cells, cyclosporine A can promote the leukemia cell apoptosis.