Effects of MSH2 gene re-expression on estrogen induced-apoptosis of colon cancer cells LOVO

Abstract

Objective To observe the effects of MSH2 gene re expression on estrogen-induced apoptosis of colon cancer cells LOVO,and to explore its mechanisms.Methods According to different plasmid and whether with estradiol intervention,colon cancer LOVO cells were divided into empty plasmid with ethanol group,empty plasmid with estradiol group,MSH2 with ethanol group,MSH2 with estradiol group,estrogen receptor (ER) β with ethanol group,ERβ with estradiol group,ERβ with MSH2 and ethanol group and ERβ with MSH2 and estradiol group,and received corresponding treatment.The expression of MSH2,ERβ protein and apoptosis related caspase 3 protein were detected by Western blotting.Cell viability was measured by cell counting kit-8.Cell DNA fragments of each group were isolated with apoptosis DNA fragments isolation kit.And the DNA ladder was observed.The rate of apoptosis was detected by flow cytometer.Single factor variance analysis was performed for comparison among multiple groups,and t test was used for comparison between the two groups.Results After transfection,the expression of the MSH2 and ERβ at protein level in LOVO cells significantly increased and neither of their expression was effected by estradiol.The expression levels of caspase 3 cleavaged active fragments of ERβ with estradiol group and ERβ with MSH2 and ethanol group were higher than other groups,and there was no significant difference between these two groups.The LOVO cell viability of empty plasmid with ethanol group,empty plasmid with estradiol group,MSH2 with ethanol group,MSH2 with estradiol group,ERβ with ethanol group,ERβ with estradiol group,ERβ with MSH2 and ethanol group and ERβ with MSH2 and estradiol group was 1.72 ±0.25,1.74 ± 0.31,1.77 ± 0.35,1.74±0.33,1.70±0.34,1.02±0.48,1.71±0.31 and 1.07±0.18,respectively,and the differences between the groups were statistically significant (F=3.791,P＜0.05).Among them,the LOVO cell viability of ERβ with estradiol group was lower than that of ERβ with ethanol group,accordingly,that of ERβ with MSH2 and estradiol group was lower than that of ERβ with MSH2 and ethanol group,that of ERβ with estradiol group was lower than that of empty plasmid with estradiol group,that of ERβ with MSH2 and estradiol group was lower than that of MSH2 with estradiol group,and the differences were statistically significant (t=3.158,3.075,3.648,3.253,all P＜0.05).DNA ladder formed from DNA fragments of apoptosis cells was seen in ERβ with estradiol group and ERβ with MSH2 and estradiol group.The apoptosis rate of empty plasmid with ethanol group,empty plasmid with estradiol group,MSH2 with ethanol group,MSH2 with estradiol group,ERβ with ethanol group,ERβ with estradiol group,ERβ with MSH2 and ethanol group and ERβ with MSH2 and estradiol group was 7.86±0.19,7.87±0.39,8.39±1.02,9.05±1.54,7.54±0.99,19.77±2.35,7.76±1.32 and 19.30±1.75,respectively,and the differences between groups were statistically significant (F=45.436,P＜0.05).Among them,the apoptosis rate of ERβ with ethanol group was lower than that of ERβ with estradiol group,that of ERβ with MSH2 and ethanol group was lower than that of ERβ with MSH2 and estradiol group,that of empty plasmid with estradiol group was lower than that of ERβ with estradiol group,that of ERβ with MSH2 and estradiol group was lower than that of MSH2 with estradiol group,and the differences were statistically significant (t =8.260,9.133,8.596,7.617,all P＜ 0.05).Conclusions Estrogen may promote colon cancer cell apoptosis through ERβ pathway.The process of apoptosis maybe related with caspase protein,MSH2 may not be involved in the regulation of this signal pathway. Key words: Colonic neoplasms; Estrogens; Estrogen receptor beta; Apoptosis; MSH2