[Valproic acid activates autophagy in multiple myeloma cell lines RPMI8226 and U266].

OBJECTIVE: To investigate the effects of valproic acid (VPA) on autophagy in multiple myeloma (MM) cell lines RPMI8226 and U266. METHODS: The method of dye acridine orange (AO) was used for observing morphological changes of autophagy under fluorescence microscope; The cell proliferation inhibition was measured by MTT assay; Cells apoptosis was evaluated by flow cytometry; Autophagy-related factors LC3, Beclin1 expressions changes were detected by real-time quantitative PCR (Real-time PCR) and western blot assay. RESULTS: AO stainings as dispersively brownish red vesicles were observed both in the control and chloroquine groups, while a lot of brownish red acidic vesicles in clusters were seen in rapamycin and VPA groups. The growths of RPMI8226 and U266 cells were suppressed by VPA treatment in a dose-and time-dependent manner, after treatment with VPA for 24 h, the IC50 were (12.03 ± 0.23) mmol/L for RPMI8226 cells and (10.16 ± 0.37) mmol/L for U266 cells respectively; Poptotie cells of RPMI8226 and U266 increased in a time-dependent manner after exposure to VPA. Real-time PCR and Western blot results of RPMI8226 and U266 cells showed that gradually increased LC3, Beclin1 mRNA and protein expressions with LC3 â to LC3 â ¡ conversion rate after increasing the concentration of VPA and prolonging duration of action of VPA. CONCLUSIONS: The results reveal disclosed the basal level of autophagy in MM cells, VPA as a autophagy activator may be one of its actions on the treatment of MM.