Green tea compounds in breast cancer prevention and treatment

Table 2 Studies of green tea catechins on breast cancer treatment in animal models

Ref.	Model	Intervention	Effect on tumor size	Main mechanisms
Gu et al[39], 2013	8-wk-old female C57BL/6 mice were inoculated with 106 E0771 cells into the left fourth mammary gland fat pad	After cells were inoculated, mice received EGCG (around 50-100 mg/kg per day) in drinking water for 4 wk and 8 control mice received water only	(1) Tumor cross section area reduced 65% (P < 0.01); (2) tumour weight reduced 68% (P < 0.01); and (3) no difference in body weight, heart weight, kidney weight, or urinary protein	Inhibition of vascular endothelial growth factor (VEGF) expression and tumor angiogenesis via inhibiting hypoxia-inducible factor 1α and nuclear factor κB activation
Mineva et al[40], 2013	6-wk-old female nonobese diabetic/severe combined immunodeficiency mice were implanted with 5 × 103 SUM-149 cells in the fourth inguinal mammary fat pad	After 25 d, mice were intraperitoneally injected with 16.5 mg/kg EGCG or control PBS five times a week for the first five weeks and daily for the last week	(1) Tumor volume decreased 37.7% ± 4.4%; (2) tumor weight decreased 28.6% ± 6.5%; and (3) the lymphatic vessel density at the periphery of tumors decreased in EGCG-treated mice	EGCG decreased levels of VEGF-D RNA and VEGF-D protein
Jang et al[42], 2013	4T1 cells (105) were injected subcutaneously into either side of the posterior flank of BALB/c mice	On the 7th, 9th, 11th days after cell injection, mice were intraperitoneally injected with either EGCG (10 mg/kg) or PBS control	On day 30 after cell injection, a significant decrease of tumor volume and weight was observed in the EGCG-treated group vs the control group (P < 0.0005)	EGCG inhibited expression of CSF-1, CCL-2, IL-6 and transforming growth factor-β, and induced tumor necrosis factor-α expression
Thangapazham et al[43], 2007	5-wk-old female athymic nude mice (NCr-nu/nu) were implanted with 5 × 106 MDA-MB-231 cells in the mammary fat pad	After cell inoculation, one group of animals received 1% polyphenols from green tea (GTP) as a sole source of drinking water and the other group received a dose of 1 mg/animal of EGCG or water as control	At the end of 10 wk, the tumor volume was reduced by 45% and 61% in the EGCG and GTP treated groups, respectively (P < 0.05). All animals appeared healthy with no loss of body weight	EGCG and GTP fed animals showed increased apoptosis and decreased proliferation

DMBA: Dimethyl-benzanthracene; EGCG: Epigallocatechin-3-gallate; VEGF: Vascular endothelial growth factor.