Chemopreventive effects of tea extracts and various components on human pancreatic and prostate tumor cells in vitro

Pancreatic and prostate cancers pose serious problems to human health. To d etermine the potential for chemopreventive intervention against pancreatic and prostate cancers, black and green tea extracts and components of these extracts were examined in vitro for their effect on tumor cell growth. Comp onents included a mixture of polyphenols from green tea (GTP), mixtures of polyphenols (BTP) and of theaflavins (MF) from black tea, and the purified components epicatechin-3-gallate (ECG) and epigallocatechin-3-gallate (EGCG ). Two human cell lines, pancreatic adenocarcinoma (HPAC) and prostate tumo r (LNCaP) were exposed to these agents for 24 hours. Results showed inhibit ion (approx 90%) of cell growth in pancreatic tumor cells by black and gree n tea extracts (0.02%). GTP (10 mu g/ml) and MF (100 mu g/ml) significantly inhibited growth (approx 90%); ECG and EGCG inhibited growth as well (appr ox 95%). Black and green tea extracts, GTP, and EGCG decreased the expressi on of the K-ras gene, as determined by reverse transcription-polymerase cha in reaction. Green and black tea extracts decreased the multidrug-resistant gene (mdr-1), although GTP and EGCG increased expression. Similar data wer e obtained in the prostate cell line LNCaP. All agents significantly inhibi ted, growth. These agents increased expression of the mdr-1 gene. This stud y suggests that components from black and green tea extracts can modulate t he expression of genes known to play a role in the carcinogenesis process a nd, therefore, may be potential agents for chemoprevention against pancreat ic cancer.