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

To investigate the effects of valproic acid (VPA) on autophagy in multiple myeloma (MM) cell lines RPMI8226 and U266.

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.

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 Ⅰ to LC3 Ⅱ conversion rate after increasing the concentration of VPA and prolonging duration of action of VPA.

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.