0034 Chemopreventive effect of green tea extract and tamoxifen on mouse mammary preneoplastic lesions

Abstract

Goals: Our goal is to investigate the chemopreventive effect of green tea extract (GTE) and tamoxifen (TAM) alone or in combination on mammary carcinogenesis and preneoplastic lesions of C3H/OuJ mouse. Methods: Mammary tumors of C3H/OuJ mouse induced by exogenous MMTV frequently arise from preneoplastic lesions termed hyperplastic alveolar nodules (HANs). Mice were divided into five groups; (1) no treatment as control, (2) 1%GTE orally administered with drinking water, (3) 0.5%GTE orally, (4) TAM pellet subcutaneously administered (10mg /body/3months), (5) 1%GTE orally and TAM subcutaneously in combination. The treatment was started at 10 week-old and observed the tumor formation. At 48 week-old, mice were sacrificed and mammary glands were removed, stained with methylene blue for HAN count, and with silver nitrate for counting Nucleolar Organizer Regions (AgNORs). Results: The tumor incidence of control group, 1%GTE group, 0.5%GTE group, TAM group and combination group was 30%, 25%, 25%, 14% and 0%, respectively, but not significantly different. Average HAN count of control group, 1%GTE group, 0.5%GTE group, TAM group and combination group was 9.2, 6.1, 7.5, 6.0 and 5.8, respectively. HAN formation was significantly reduced in 1%GTE group, TAM group and combination group compared with control group. Average AgNOR count of control group, 1%GTE group, 0.5%GTE group, TAM group and combination group was 2.862/cell, 1.886, 1.993, 1.697 and 1.590, respectively. AgNOR formation was significantly reduced in 1%GTE group, TAM group and combination group compared with control group. Conclusion: These data suggest that GTE and TAM have some potential in chemoprevention of breast cancer, individually and in combination.