Cell cycle arrest and apoptosis induction in human prostate cancer cell lines (PC-346C, LNCaP and PC-3) by the green tea ingredient EGCG (Epigallocatechingallate)

Objectives: Prostate cancer (PC) is the most common type of cancer found in German men. Medicine Worldwide estimates that about 19% of all new cases of cancer in Germany every year will be PC. It was recently shown that oral consumption of green tea polyphenols inhibited prostate carcinogenesis and suggested that induction of apoptosis in PC cells is responsible for this effect. Much of the chemopreventive effects of green tea are attributed to its major polyphenolic constituent EGCG.

Methods: LNCaP, PC-346C and PC-3 cells were treated with EGCG (10uM, 20uM, 30uM, 40uM, 50uM, 100uM) for 2h, 4h, 6h, 12h, 24h and 36h. Adherent cells remaining after treatment were detected by Crystal Violet Assay. For cell cycle and Apo-BrDU data, we used 50uM EGCG for 24h. Etoposide was used for positive control. For immunohistochemical visualization, we stained the cell lines with HE, PCNA and Tunel-POD.

Results: 50uM EGCG inhibited cell growth in all cell lines significantly after 24h compared to vehicle control (EtOH). Higher concentrations and longer exposure of EGCG led to PC cell death in all treated groups. Cell cycle data showed significant S-phase arrest in all cell lines used. Furthermore, EGCG induced significant apoptosis in PC-346C and LNCaP cells. Immunohistochemical data showed significantly lower proliferation and induction of apoptosis after treatment with 50uM EGCG at all time points compared to vehicle control.

Conclusion: This and further studies may validate the use of EGCG as a mild, natural agent for PC prevention or even treatment.