Sulforaphane Combined with Vitamin D Induces Cytotoxicity Mediated by Oxidative Stress, DNA Damage, Autophagy, and JNK/MAPK Pathway Modulation in Human Prostate Tumor Cells

Prostate cancer ranks second in incidence worldwide. To date, there are no available therapies to effectively treat advanced and metastatic prostate cancer. Sulforaphane and vitamin D alone are promising anticancer agents in vitro and in vivo, but their low bioavailability has limited their effects in clinical trials. The present study examined whether sulforaphane combined with vitamin D at clinically relevant concentrations improved the cytotoxicity of the compounds alone towards DU145 and PC-3 human prostate tumor cells. To assess the anticancer activity of this combination, we analyzed cell viability (MTT assay), oxidative stress (CM-H(2)DCFDA), autophagy (fluorescence), DNA damage (comet assay), and protein expression (Western blot). The sulforaphane–vitamin D combination (i) decreased cell viability, induced oxidative stress, DNA damage, and autophagy, upregulated BAX, CASP8, CASP3, JNK, and NRF2 expression, and downregulated BCL2 expression in DU145 cells; and (ii) decreased cell viability, increased autophagy and oxidative stress, upregulated BAX and NRF2 expression, and downregulated JNK, CASP8, and BCL2 expression in PC-3 cells. Therefore, sulforaphane and vitamin D in combination have a potential application in prostate cancer therapy, and act to modulate the JNK/MAPK signaling pathway.