Combination of α-Tomatine and Curcumin Inhibits Growth and Induces Apoptosis in Human Prostate Cancer Cells

alpha-Tomatine is a glycoalkaloid found in tomatoes and curcumin is a major yellow pigment of turmeric. In the present study, the combined effect of these two compounds on prostate cancer cells was studied. Treatment of different prostate cancer cells with curcumin or alpha-tomatine alone resulted in growth inhibition and apoptosis in a concentration-dependent manner. Combinations of alpha-tomatine and curcumin synergistically inhibited the growth and induced apoptosis in prostate cancer PC-3 cells. Effects of the alpha-tomatine and curcumin combination were associated with synergistic inhibition of NF-kappa B activity and a potent decrease in the expression of its downstream gene Bcl-2 in the cells. Moreover, strong decreases in the levels of phospho-Akt and phosphor-ERK1/2 were found in PC-3 cells treated with alpha-tomatine and curcumin in combination. In animal experiment, SCID mice with PC-3 xenograft tumors were treated with alpha-tomatine and curcumin. Combination of alpha-tomatine and curcumin more potently inhibited the growth of PC-3 tumors than either agent alone. Results from the present study indicate that alpha-tomatine in combination with curcumin may be an effective strategy for inhibiting the growth of prostate cancer.