Rubone (2'-Hydroxy-2,4,4',5,6'-pentamethoxychalcone), a natural product and a modulator of miR-34a (microRNA-34), upregulates miR-34a expression in a p53-dependent manner, which in turn downregulates the expression of downstream targets Bcl-2, cyclin-D1, CDK6, SIRT1, and FOXP1, thereby inhibiting tumor growth and reversal of hepatocellular carcinoma (HCC) and chemoresistance in prostate cancer.