ABSTRACT
Objective:To evaluate the biological functions and underlying mechanisms of transcription factor PAX5 in promoting cell proliferation and anti-apoptosis in multiple myeloma cells.Methods:a PAX5 knockdown cell line was established by stable transfection of vector-based PAX5-siRNA into multiple myeloma IM9 cells.The expressing level of PAX5,p53,XBP-1 and c-Myc was examined by either or both Western blot and RT-PCR for the targets.Cell proliferation and apoptosis were assayed by MTT and flow cytometry,respectively.Results:PAX5 was expressed selectively in IM9 cells,but neither in another common used multiple myeloma KAS6 cells nor in the prostate cancer cells DU145 and PC3.Knockdown PAX5 led to a significant up-regulation of p53 and XBP1,but decreased c-Myc expressions in IM9 cells that were correlated with the increased sensitivity of drug-induced apoptosis and decreased proliferation rates when compared to the control cells.Conclusion:PAX5 is specifically expressed in IM9 cells,which promotes cell proliferation and anti drug-induced apoptosis.In addition to inhibiting the expression of p53 and XBP-1,PAX5 is found to induce expression of oncogene c-Myc in IM9 cells,and this finding indicates an undiscovered signal pathway that may contributes to the malignancy of Multiple Myeloma cells.