Beta-Hydroxyisovalerylshikonin Inhibits the Growth of U266 Multiple Myeloma Cells by Triggering the Mitochondrial Pathway

Background: Beta-hydroxyisovalerylshikonin (beta-HIVS) is a compound isolated from the traditional oriental medicinal herb lithospermum radix. This drug exerts a role as an ATP non-competitive inhibitor of Protein-Tyrosine Kinases (PTKs) and shows great potential for induction of apoptosis against human cancer cells. We investigated the effect of beta-HIVS on multiple myeloma U266 cells and clarified details of the primary mechanism in its apoptosisinducing activity. Objective: The aim of this work was to trace the apoptosis-inducing activity of beta-HIVS on U266 cells as well as the underlying mechanisms. Methods: Cell Counting Kit-8 (CCK-8) test and colony-forming assay were performed in estimating the effects of beta-HIVS on U266 cell viability and colony formation. Apoptosis analysis was carried out on the basis of DAPI fluorescence staining and DNA fragmentation assays. Real-time PCR was employed to evaluate changes of Bcl-2 and Bax mRNA expression, while indirect immunofluorescence assay and western blotting were utilized in validating the expression of Bcl-2, Bax, caspase-3, caspase-9, PARP and cytochrome c. Results: CCK-8 test and colony-forming assay showed that beta-HIVS treatment resulted in significantly reduced cell proliferation (P<0.05 or 0.01) and colony formation (P<0.01). Real-time PCR results indicated that the expression level of Bcl-2 mRNA was reduced at 72h following beta-HIVS co-cultivation (P<0.01), although Bax mRNA altered with no significance. Immunofluorescence assay displayed that caspase-3 was activated in betaHIVS treated group, accompanied by an increased expression of cytochrome c. Western blotting also exhibited that the expression of Bcl-2 protein in beta-HIVS treated group decreased and cytochrome c increased at 72h after co-cultivation. Moreover, caspase-3 and -9, as well as PARP were activated, all with P<0.01 when compared with the two control groups. Conclusion: Beta-HIVS revealed remarkable apoptosis-inducing activity in U266 cells, possibly by inhibiting proliferation and promoting apoptosis via the mitochondrial pathway. Citation: He Y, Chen X, Kong L (2014) Beta-Hydroxyisovalerylshikonin Inhibits the Growth of U266 Multiple Myeloma Cells by Triggering the Mitochondrial Pathway. J Leuk 2: 155. doi:10.4172/2329-6917.1000155