Aim: To investigate the effects of curcumin on proliferation and apoptosis in testicular cancer cells in vitro and to investigate its molecular mechanisms of action.
Methods: NTera-2 human malignant testicular germ cell line and F9 mouse teratocarcinoma stem cell line were used. The anti-proliferative effect was examined using MTT and colony formation assays. Hoechst 33258 staining, TUNEL and Annexin V-FITC/PI staining assays were used to analyze cell apoptosis. Protein expression was examined with Western blot analysis and immunocytochemical staining.
Results: Curcumin (5, 10 and 15 μmol/L) inhibited the viability of NTera-2 cells in dose- and time-dependent manners. Curcumin significantly inhibited the colony formation in both NTera-2 and F9 cells. Curcumin dose-dependently induced apoptosis of NTera-2 cells by reducing FasL expression and Bcl-2-to-Bax ratio, and activating caspase-9, -8 and -3. Furthermore, curcumin dose-dependently reduced the expression of AP transcription factor AP-2γ in NTera-2 cells, whereas the pretreatment with the proteasome inhibitor MG132 blocked both the curcumin-induced reduction of AP-2γ and antiproliferative effect. Curcumin inhibited ErbB2 expression, and decreased the phosphorylation of Akt and ERK in NTera-2 cells.
Conclusion: Curcumin induces apoptosis and inhibits proliferation in NTera-2 cells via the inhibition of AP-2γ-mediated downstream cell survival signaling pathways.