Regulation of cell growth through cell cycle arrest and apoptosis in HPV 16 positive human cervical cancer cells by tea polyphenols

Cervical cancer is the second most common malignant neoplasm in women, in terms of both incidence and mortality rates worldwide. The polyphenolic constituents of tea (Camellia sinensis) have gained considerable attention because of its anti-cancer properties against a variety of cancers. Here we studied the effects of green and black tea polyphenols (GTP and BTP), on cellular proliferation and cell death in the SiHa cells (human cervical cancer) expressing the human papilloma virus (HPV)-16. The result showed that both GTP and BTP inhibited proliferation of cells in dose and time dependent manner. Cell cycle analysis showed anti-proliferative effect of GTP which is associated with an increase in the G2/M phase and apoptotic effect of BTP in 24 h treated SiHa cells. Further, on increase of incubation time for 48 h, GTP caused induction of apoptosis up to 20% of SiHa cells. The role GTP and BTP in apoptosis was further confirmed by reduction in mitochondrial membrane potential and increased levels of membrane phosphatidylserine. Thus, our data suggests that tea polyphenols exhibit anti-cancer potential against cervical cancer by inhibition of cell growth and induction of apoptosis.