Inhibition of CWR22Rν1 tumor growth and PSA secretion in athymic nude mice by green and black teas

Abstract

Cancer of the prostate gland (CaP), the most common invasive malignancy and a major cause of cancer related deaths in male population in the USA, is an ideal candidate disease for chemoprevention because it is typically detected in elderly population with a relatively slower rate of growth and progression. Many dietary phytochemicals are showing promising chemopreventive effects, at-least in pre-clinical models of CaP. Our published data in cell culture and animal studies, supported by the work from other laboratories, as well as epidemiological observations and case-control studies, suggest that polyphenols present in green tea possess CaP chemopreventive and possibly therapeutic effects. This present study was designed to compare CaP cancer chemopreventive effects of green tea polyphenols (GTP), water extract of black tea, and their major constituents epigallocatechin-3-gallate and theaflavins, respectively, in athymic nude mice implanted with androgen-sensitive human CaP CWR22Rnu1 cells. Our data demonstrated that the treatment with all the tea ingredients resulted in (i) significant inhibition in growth of implanted prostate tumors, (ii) reduction in the level of serum prostate specific antigen, (iii) induction of apoptosis accompanied with upregulation in Bax and decrease in Bcl-2 proteins, and (iv) decrease in the levels of VEGF protein. Furthermore, we also found that GTP (0.01 or 0.05% w/v; given after establishment of CWR22Rnu1 tumor) causes a significant regression of tumors suggesting therapeutic effects of GTP at human achievable concentrations.

Catechin as an antioxidant in liver mitochondrial toxicity: Inhibition of tamoxifen‐Induced protein oxidation and lipid peroxidation

“…To examine whether the TAM-stimulated H 2 O 2 is related to a decrease in activity of the mitochondrial enzyme that detoxifies H 2 O 2 , we studied mitochondrial GPx. TAM treatment is reported to reduce the activity of cytoplasmic GPx in rats [23]. We observed that the mitochondrial GPx activity was reduced by TAM.…”

Tea, Coffee and Prostate Cancer

“…In addition, black tea extract has recently showed a significant protective effect against testosterone induced oxidative injury in Wistar rat prostate [64]. Significant inhibition in growth of implanted prostate tumors in athymic nude mice and reduction in prostate specific antigen was also recently reported with treatment of water extract of black tea, theaflavins as well as green tea polyphenols [65].…”

Src kinase potentiates androgen receptor transactivation function and invasion of androgen-independent prostate cancer C4-2 cells

“…Protein extraction and western blotting Protein lysates from cultured cells were prepared, 40 mg protein was subjected to SDS-polyacrylamide gel electrophoresis (PAGE) and western blot was performed as previously described (Siddiqui et al, 2006). The extraction of tumor proteins from TRAMP mice has been described previously (Adhami et al, 2004).…”