Development of a rat model by 3,4-benzopyrene intra-pulmonary injection and evaluation of the effect of green tea drinking on p53 and bcl-2 expression in lung carcinoma.
BACKGROUND
A convenient animal model of primary lung cancer is compelling for investigation into the disease mechanisms and for development of therapeutic strategies. This study aims to develop a reproducible rat model for lung carcinoma by intra-pulmonary injection of 3,4-benzopyrene, and to evaluate the preventive effect of green tea on the formation of lung carcinoma.


METHODS
Sprague-Dawley rats of the same ages were randomly assigned into three groups treated differently. Rats in group one were given green tea in drinking water (tea concentration: 1.2%; tea polyphenols in the tea solution: 0.3%); rats in the groups two and three were given blank drinking water. Rats in the groups one and two were injected intra-pulmonarily with 3,4-benzopyrene dissolved in corn oil (2 mg/0.2 mL/injection, fortnightly, 4 times in all); rats in the group three were injected with the vehicle corn oil as the control for injection. All the rats were sacrificed one year after the first intra-pulmonary injection. Tumors developed in rats and lung tissues were collected for carcinoma diagnosis and for p53 and bcl-2 expression.


RESULTS
Intra-pulmonary injection of 3,4-benzopyrene steady induced lung carcinoma at a success rate of 75%. Administration with green tea drinking significantly reduced the incidence of lung carcinoma to 30%. Green tea up-regulated p53 expression in lung carcinoma, but significantly down-regulated bcl-2 expression.


CONCLUSIONS
Intra-pulmonary injection of 3,4-benzopyrene can steady induce lung carcinoma in rats, and green tea has preventive effect against lung cancer possibly by regulating expression of some critical genes such as p53 and bcl-2.
Gu
Qihua
Q
Department of Respiratory Medicine, Xiangya Hospital affiliated to Central South University, Changsha City, Hunan 410008, PR China. docguqihua2003@yahoo.com.cn
Hu
Chengping
C
Chen
Qiong
Q
Xia
Ying
Y
Feng
Juntao
J
Yang
Hongzhong
H
D000818:Animals; D016588:Anticarcinogenic Agents / Q000627:therapeutic use*; D001564:Benzo(a)pyrene; D002277:Carcinoma / Q000139:chemically induced / Q000235:genetics / Q000378:metabolism / Q000517:prevention & control; D018890:Chemoprevention; D004195:Disease Models, Animal; D015536:Down-Regulation; D005260:Female; D005419:Flavonoids / Q000627:therapeutic use; D015972:Gene Expression Regulation, Neoplastic; D008175:Lung Neoplasms / Q000139:chemically induced / Q000235:genetics / Q000378:metabolism / Q000517:prevention & control; D010636:Phenols / Q000627:therapeutic use; D010936:Plant Extracts / Q000627:therapeutic use*; D059808:Polyphenols; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013662:Tea; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation
D016588:Anticarcinogenic Agents; D005419:Flavonoids; D010636:Phenols; D010936:Plant Extracts; D059808:Polyphenols; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D013662:Tea; D016159:Tumor Suppressor Protein p53; D001564:Benzo(a)pyrene