ABSTRACT
Background and purpose:Estrogen receptor (ER)-positive breast cancer always presents a dilemma for resistance to endocrine therapy in a long time. The recent studies showed that the expression of estrogen-responsive ifnger protein (Efp) and polo-like kinase 3 (Plk3) had a close relationship with breast cancer development. This study was to explore the expression correlation between Efp and Plk3 in ER-positive breast cancer in order to understand the inlfuence of Efp and Plk3 on the drug resistance.Methods:The expression of Efp and Plk3 in 74 cases of ER-positive breast cancer was detected by SP immunohistochemistry. The clinical signiifcance was then analyzed. Real-time lfuorescent quantitative polymerase chain reaction (RTFQ-PCR) and Western blot were used to detect the expression of Efp and Plk3 in ER-positive MCF-7 cells.Results:No signiifcant relationship was found between Efp and Plk3 expression and the clinicopathological features of 74 cases of ER-positive breast cancer (P>0.05). The number of cases whose Efp showed positive expression was 51 (68.9%), while the number of cases whose Plk3 showed positive expression was 23 (31.1%). Chi-square test analysis showed the expression of Efp and Plk3 was negatively correlated in 74 cases of ER-positive breast cancer (χ2=8.837,P<0.05). The result of RTFQ-PCR showed that the expression of Efp mRNA in MCF-7 cells was up-regulated by estrogen stimulation, whereas Plk3 mRNA was not changed. The result of Western blot showed that the expression of Efp protein in MCF-7 cells was increased by estrogen and MG132 stimulation, whereas Plk3 protein was decreased.Conclusion:The expression of the Efp protein is negatively correlated with Plk3 protein in ER-positive breast cancer. High expression of Efp may be involved in the resistance to endocrine therapy.
ABSTRACT
PURPOSE: 14-3-3 sigma (sigma) is considered to be an important tumor suppressor and decreased expression of the same has been reported in many malignant tumors by hypermethylation at its promoter or ubiquitin-mediated proteolysis by estrogen-responsive ring finger protein (Efp). In this study, we investigated the significance of 14-3-3 sigma expression in human breast cancer and its regulatory mechanism. METHODS: Efp was silenced using small interfering RNA (siRNA) in the MCF-7 breast cancer cell line in order to examine its influence on the level of 14-3-3 sigma protein. The methylation status of the 14-3-3 sigma promoter was also evaluated by methylation-specific polymerase chain reaction (PCR). The expression of Efp and 14-3-3 sigma in 220 human breast carcinoma tissues was assessed by immunohistochemistry. Other clinicopathological parameters were also evaluated. RESULTS: Silencing Efp in the MCF-7 breast cancer cell line resulted in increased expression of 14-3-3 sigma. The Efp-positive human breast cancers were more frequently 14-3-3 sigma-negative (60.5% vs. 39.5%). Hypermethylation of 14-3-3 sigma was common (64.9%) and had an inverse association with 14-3-3 sigma positivity (p=0.072). Positive 14-3-3 sigma expression was significantly correlated with poor prognosis: disease-free survival (p=0.008) and disease-specific survival (p=0.009). CONCLUSION: Our data suggests that in human breast cancer, the regulation of 14-3-3 sigma may involve two mechanisms: ubiquitin-mediated proteolysis by Efp and downregulation by hypermethylation. However, the inactivation of 14-3-3 sigma is probably achieved mainly by hypermethylation. Interestingly, 14-3-3 sigma turned out to be a very significant poor prognostic indicator, which is in contrast to its previously known function as a tumor suppressor, suggesting a different role of 14-3-3 sigma in breast cancer.
Subject(s)
Humans , Breast , Breast Neoplasms , Cell Line , Disease-Free Survival , Down-Regulation , Fingers , Immunohistochemistry , Methylation , Polymerase Chain Reaction , Prognosis , Proteolysis , RNA, Small InterferingABSTRACT
Objective To observe the effects of chronic arsenic exposure on mRNA expression of estrogen receptor-binding fragment-associated gene 9 (Ebag9) and estrogen-responsive finger protein (efp) in uterus and ovary of female rats.Methods Fifty female Wistar rats were randomly divided into five groups according to arsenic (As2O3) concentrations given through drinking-water:0.00 (control),0.05,0.10,0.20,0.40 mg/L arsenic exposure groups and real-time RCR (RT-PCR) was used to detect the mRNA expression of Ebag9 and efp in uterus and ovary tissue at the 31 weeks of experiment.Results The mRNA expression levels of Ebag9 and efp of the 0.00,0.05,0.10,0.20,0.40 mg/L arsenic exposure groups were respectively as follows:0.761 ± 0.178,0.521 ± 0.130,0.544 ± 0.035,0.525 ± 0.198,0.498 ± 0.240 and 0.795 ± 0.171,0.874 ± 0.077,0.797 ± 0.066,0.796 ± 0.040,0.832 ± 0.096.Compared with control group,a decreased tendency was observed in Ebag9 mRNA level(with P value 0.055 in 0.40 mg/L arsenic exposure group) and increased tendency in efp mRNA level in experimental groups (all P ＞ 0.05).The mRNA expression levels of Ebag9 and efp in ovary of the five groups were by turns:0.702 ± 0.484,0.719 ± 0.336,0.693 ± 0.095,0.706 ± 0.055,0.728 ± 0.073 and 0.924 ± 0.061,1.009 ± 0.034,0.930 ± 0.085,0.929 ± 0.068,1.012 ± 0.101.Compared with control group,the expression level of Ebag9 mRNA showed a increased tendency in 0.05,0.20,0.40 mg/L arsenic exposure groups(all P ＞ 0.05).The efp mRNA level increased in experimental groups,with significant difference in 0.05,0.40 mg/L groups (all P ＜ 0.05).Conclusions The expression of efp mRNA has changed in ovary of female rats exposed to chronic arsenic.Arsenic may act as an environmental endocrine disruptor to exert its effect.
ABSTRACT
Objective To observe the effects of chronic arsenic exposure on estrogen receptor-binding fragment-associated gene 9 (Ebag9) and estrogen-responsive finger protein (efp) mRNA expression in female rat' s myocardium.Methods Fifty female Wistar rats were randomly divided into five groups according to arsenic (As2O3) concentrations in drinking-water:0.00(control),0.05,0.10,0.20,0.40 mg/L groups and RT-PCR was used to detect Ebag9 and efp mRNA expression of myocardium at the 32 weeks of experiment.Results Ebag9 and efp mRNA expression levels in 0.00,0.05,0.10,0.20,0.40 mg/L groups were respectively as follows:0.54 ±0.14,0.52 ± 0.10,0.48 ± 0.24,0.58 ± 0.13,0.45 ± 0.19 and 0.85 ± 0.14,0.86 ± 0.12,0.87 ± 0.09,0.99 ±0.10,0.86 ± 0.19.Compared to the control group,Ebag9 mRNA level of the 0.20 mg/L group was increased,and decreased in other groups,but the difference between two groups was not significant(all P ＞ 0.05).Compared to control group,the efp mRNA level of 0.20 mg/L group increased significantly(P ＜ 0.05),and showed increased tendency in other arsenic groups,but the difference between two groups was not significant (all P ＞ 0.05).Conclusions Ebag9 and efp mRNA expression have changed in myocardium of rats exposed to chronic arsenic.Arsenic may has endocrine disruptor effect to female rat's myocardium.