OBJECTIVETo investigate the effects of valproic acid(VPA) on the expression of intracellular domain of Notch1 (ICN1) and Hes1 in multiple myeloma RPMI 8226 cell line.

METHODSExperiments were divided into 4 group: blank control group and groups of cells treated with VPA of different concentration (2, 4, 8 mmol/L), the cell proliferation was detected by MTT method, RT-PCR was applied to detect the mRNA expression level of ICN1 and Hes1. Western blot was used to detect the protein expression of ICN1 and Hes1.

RESULTSThe proliferation of the RPMI 8226 cell was obviously inhibited by different concentration of VPA (2, 4, 8 mmol/L) at the same time. The same concentration of VPA was used to treat RPMI8226 cell for different time (24, 48, 72 h), the cell proliferation was obviously inhibited. Compared with control group, the mRNA and protein expression of ICN1 was significantly depressed at different concentration of VPA(2, 4, 8 mmol/L) for 48 h (P<0.05). Compared with control group, the mRNA and protein expression of Hes1 was depressed at different concentration 2, 4, 8 mmol/L)of VPA for 48 h (P<0.05).

CONCLUSIONVPA inhibits the proliferation of the RPMI 8226 cell in a time- and dose- dependent manner; VPA down-regulates the mRNA and protein expression level of ICN1 and Hes1 in RPMI8226 cell; thus VPA might inhibit cell proliferation possibly through the inhibition of Notch signaling pathway in multiple myeloma cells.