The Role Of Estrogen And Estrogen Receptor In Lewis Lung Cancer Of C57BL/6 Mice

Objective:To explore the effect of estrogen and estrogen receptor（ER） on tumor progression in Lewis lung carcinoma of female mice.The current study’s findings will provide experimental evidence for anti-estrogen therapy as a new method of adenocarcinoma of the lung.Methods:Cell suspension of Lewis lung carcinoma was injected subcutaneously into the armpit of right anterior superior limbs of 120 female C57BL/6 mice.Seven days later,tumor-bearing mice were divided randomly into four groups for each thirty（n=30）:Control group,estrogen（E₂） group,tamoxifen（TAM） group and estrogen/tamoxifen（E₂/TAM）group.Every group were evenly divided into group A and group B for each fifteen（n=15）.In group A,tumor volume,weight of tumors and inhibitive rate were estimated. In addition,expression of ERα,ERβ and Ki-67 were observed by immunohistochemistry.On day21,all animals in group A（n=60）were sacriced by cervical dislocation.All animals in group B（n=60） were fed till death or sacriced on day 70 to observe survival time.Results:In the E₂ group,tumor volume was significantly higher than that in the Control group（F=282.159,P<0.01）.In the TAM group,tumor volume was significantly lower than that in the Control group（F=8.875,P=0.006）.Tumor volume in the E₂/TAM group was similar to that in the Control group（F=0.113,P=0.740）.In the E₂ group（6.427±1.155）,the weight of tumors was significantly higher than that in the Control group（4.673±0.697）（P<0.01）.In the TAM group（2.893±0.470）,the weight of tumors was significantly lower than that in the Control group（P<0.01）.The weight of tumors in the E₂/TAM group（4.887±1.476） was similar to that in the Control group（P=0.458）.The inhibitive rate of tumor of E₂ group,TAM group and E₂/TAM group were-37.53%、38.09%、-4.58%,respectively.In the E₂ group,the positive rate of ERβ was higher than in the Control group（P=0.02）.In the TAM group,the positive rate of ERβ was significantly lower than that in the Control group（P=0.039）.In the E₂ group,the positive rate of Ki-67 was higher than that in the Control group（P=0.036）. In the TAM group,the positive rate of Ki-67 was significantly lower than that in the Control group（P=0.020）.All indicators in the E₂/TAM group were similar to thosein the Control group（all P >0.05）.ERα were all negative in four groups.E₂ group（23.40±3.906） resulted in shortened survival compared with the Control group（36.13±6.323）（P<0.01）.While TAM group（48.07±8.481） resulted in prolonged survival compared with the Control group（P<0.01）.Survival time in E₂/TAM group（33.27±7.116） was similar to those in the Control group（ P =0.244）.Conclusion:The present study demonstrated that estrogen promoted the development of adenocarcinoma of the lung in female Lewis lung carcinoma of mice by combining with the estrogen receptor β,and shorten their survival time.However,tamoxifen,as a kind of selective estrogen receptor modulators,can inhibit the progression of tumors and extend the suvival time.In conclusion,anti-estrogen therapy can be a novel method for adenocarcinoma of the lung.