| Objective: At present, studies on antitumor are more and more focused on reducing and delaying the incidence of cancer, results from some experiments indicated that cancer prevention can be achieved by many approaches. The antitumor action of natural dietetic products with multifunction is becoming increasing popular because of their known safety for long-term administration. Most of the green tea polyphenols are flavonoils, commonly known as catechins. Some major green tea catechins are epigallocatechin-3-gallate (EGCG), epigallocatechin (EGC), epicatechin-3-gallate (ECG), epicatechin (EC), EGCG may account for up to 50% of the total catechin. Many studies show that GTC has many kinds of pharmacological effect, such as antioxidant, anti-bacterial and anti-viral, anti-aging, anti-inflammatory and anti-mutagenic effects, improving immunity of bodies, lowering blood sugar and blood lipid and so on. The antitumor function of GTC has been investigated in many laboratories, but its mechanism is not clear. On the basis of epidemiological observations and laboratory researches, in this study we examined the possible chemopreventive mechanism of GTC on DMBA-induced breast cancer in rats and the perspective on clinical application.Methods: 171 female SD rats, 4 weeks old, are divided randomly into control, DMBA model, GTC and DMBA+GTC groups by body weight. All rats are given free access to high lipid feed. At 6 weeks age DMBA and DMBA+GTC groups are treated with DMBA on the dose of 7mg/100g-bw. GTC and DMBA+GTC groups administrated 1ml GTC aqueous solution (containing GTC 80mg) by gavage after DMBA treatment, once a day, lasted for 20 weeks. Beginning from 5 weeks after DMBA administration the rats were palpated once a week and the time, size, location of each tumor was recorded. Rats were suicided at the ends of 4w, 8w, 12w, 16w and 20w separately. Recorded the weight of spleen and thymus, and the tissue changes of their mammary glands were observed by microscope. Following indexes are examined at different points of time: SOD, GSH-Px, MDA, TC, TG, HDL-CHO, micronucleus of sternum marrow, macrophage function, lymphocyte proliferation and NK cell activity. At the end of 20w, the expression of Bcl-2, Bax and PI6 of-4-Abstract in Englishbreast tissue on DMBA and DMBA+GTC groups was observed with the Histostain?SP test kit, and the AI (Apoptosis Index) and average optical density were measured by TUNEL.Results: 1. Tumor incidence: There are two rats which have tumor in DMBA group. one in DMBA+GTC group, and no one in control and GTC groups. With pathological examination the bud body and solid mass incidences of DMBA group are significantly higher than those of other groups (PO.05), and the occurrence rate of nipple of DMBA group is higher than those of DMBA+GTC and GTC groups, while no difference from control group (P<0.05). 2.Anti-mutation: The MN rate of DMBA group is higher than those of other groups. The MN rate of DMBA+GTC group is lower than that of DMBA group, but higher than those of other two groups. There is not different between GTC and control groups. S.Blood lipid: At the end of 8w, the TG in serum of GTC and DMBA groups is significantly lower than that of control group (P<0.05). 4. Indexes of anti-oxidation: The serum MDA of GTC group is significantly lower than those of control and DMBA groups. 5. Indexes of immunology: The macrophage function of DMBA+GTC group is significantly higher than those of other groups. The lymphocyte proliferation of DMBA+GTC group is higher than those of other groups and the control group is lowest among the four groups (P<0.05). The NK-cell activity of DMBA+GTC group is higher than those of other groups and the GTC group is the second (P<0.05). 6. The expression of the tumor related genes: There is not different expression of Bcl-2 between DMBA and DMBA+GTC group, while the expression of Bax has significant difference between two groups (/*<0.05). PI6 express more overly in DMBA+GTC than in DMBA group (P<0.05). 7. Apoptosis: No difference of AI can be fou...
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