Apoptotic markers in a prostate cancer cell line: effect of ellagic acid

Ellagic acid (EA) inhibits cell growth and induces apoptosis in cultured cells; however, the precise molecular mechanism involved in EA-induced apoptosis in prostate cancer cells is unknown. The aim of the present study was to delineate possible apoptotic pathway(s) involved in the EA-mediated chemotherapeutic effects in the LNCaP human prostatic cancer cell line. EA produced anti-proliferative effects through inhibition of rapamycin (mTOR) activation and a reduction in intracellular levels of β-catenin. Moreover, we demonstrated that EA induced apoptosis via downregulation of the anti-apoptotic proteins, silent information regulator 1 (SIRT1), human antigen R (HuR) and heme oxygenase-1 (HO-1). EA modulated the expression of apoptosis-inducing factor (AIF) resulting in a significant increase in reactive oxygen species (ROS) levels and the activation of caspase-3. Finally, we demonstrated that EA reduced both transforming growth factor-β (TGF-β) and interleukin-6 (IL-6) levels. EA treatment resulted in the increased expression of the tumor suppressor protein p21 and increased the percentage of apoptotic cells. In conclusion, the results suggest that EA treatment represents a new and highly effective strategy in reducing prostate cancer carcinogenesis.