Pomegranate extract inhibits EMT in clear cell renal cell carcinoma in a NF-κB and JNK dependent manner

Objective:Clear cell renal cell carcinoma(ccRCC)is the most common subtype of renal cell carcinoma(RCC)and is characterized by biallelic inactivation of the von Hippel-Lindau(VHL)tumor suppressor gene.One effect of VHL inactivation is hypoxia inducible factor alpha(HIFa)-independent constitutive activation of nuclear factor kappa B(NF-κB)and c-jun N-terminal kinase(JNK).Both NF-κB and JNK drive ccRCC growth and epithelial to mesenchymal transition(EMT).The purpose of this study was to determine the biochemical effects of pomegranate juice extracts(PE)on RCC cell lines.Methods:The pre-clinical effects of PE on NF-κB,JNK,and the EMT phenotype were assayed,including its effect on proliferation,anchorage-independent growth,and invasion of pVHLdeficient RCCs.Results:PE inhibits the NF-κB and JNK pathways and consequently inhibits the EMT phenotype of pVHL-deficient ccRCCs.The effects of PE are concentration-dependent and affect not only biochemical markers of EMT(i.e.,cadherin expression)but also functional manifestations of EMT,such as invasion.These effects are manifested within days of exposure to PE when diluted 2000-fold.Highly dilute concentrations of PE(106 dilution),which do not impact these pathways in the short term,were found to have NF-κB and JNK inhibitory effects and ability to reverse the EMT phenotype following prolonged exposure.Conclusion:These findings suggest that PE may mediate inhibition growth of pVHL-deficient ccRCCs and raises the possibility of its use as a dietary adjunct to managing patients with active surveillance for small,localized,incidentally identified renal tumors so as to avoid more invasive procedures such as nephrectomy.