The Expression And Molecular Mechanism Of MiR-542-5p In Serous Ovarian Cancer

Background:Ovarian cancer is one of the most common malignant tumor of the female reproductive system, with the top mortality of the female genital tract malignant tumor.The etiology of ovarian cancer is not clear.There is no obvious clinical symptoms at an early stage,more than 70% of the patients are diagnosed at an advanced stage.There is no effective strategies for cancer screening and early diagnosis,the 5-year survival rate is only 30%[1-3].It is necessary for us to explore the molecular mechanism and carcinogenesis of ovarian cancer,which can help us to find a way for early diagnosis and provide effective method for the treatment of ovarian cancer.Micro RNA(mi RNA) is a newly discovered endogenous small non-coding RNA, with the length of 19-25 nucleotides.It can negatively regulate the expression of its target genes by degrade the target m RNA or inhibit its translation directly[4].A large number of studies have shown that,mi RNA has involved in cell proliferation,differentiation,metabolism,apoptosis and other biological processes,and it has related to the occurrence and development of tumors[5].An increasing number of studies have indicated that mi RNAs are also abnormally expressed in human ovarian cancer tissues,and may play important roles inthe occurrence and development of ovarian cancer[6].These abnormally expressed mi RNAs could become the biomarkers of early diagnosis and prognostic evaluation for ovarian cancer in the future, also it may be the therapeutic target of ovarian cancer.Therefore,it is valuable to find out the possible role of mi RNA in ovarian cancer carcinogenesis and pregression.Recent studies suggest that serous ovarian cancer is derived from the the tubal epithelium instead of normal ovarian tissues[7-9].In our previous study,mi R-542-5p was found significantly under expressed in serous ovarian cancer than in normal fimbriated of the distal fallopian epithelium using micro RNA array,fold changed up to 25 times.Our data shows that mi R-542-5p may participate in origination and development of serous ovarian cancer[10].mi R-542-5p has been shown to participate in the devolopment of a wide variety of tumors,but no reports about the correlation between mi R-542-5p and ovarian cancers was reported.To further explore the expression of mi R-542-5p in serous ovarian cancer and take a insight into the molecular mechanism of carcinogenesis and progression of serous ovarian cancer.We have investigated the correlation between mi R-542-5p and serous ovarian cancer with large sample of PCR test,discussed the effective of mi R-542-5p on the malignant behavior of ovarian cancer cell lines,and the target gene of mi R-542-5p has also been observed in this study.Objectives:1. To detect the expression of mi R-542-5p in serous ovarian cancer, and analyze the correlation of its expression with clinicpathological features.2. To investigate the effect of mi R-542-5p on cell proliferation,migration,apoptosis and invasion of ovarian cancer SKOV3 cell lines.3. To predict and test mi R-542-5p target genes, take a insight into molecular of mi R-542-5p in carcinogenesis and development of serous ovarian cancer.Methods:1. Using quantitative real-time PCR to assess the expression of mi R-542-5p in 100 paraffin-embeded serous ovarian cancer tissues and 50 normal fimbriated end of the distal fallopian tissues,and assessing the results with statistic analysis.2. mi R-542-5p mimics and mimics negetive control(mimics NC) were transfected intoSKOV3 cell lines.MTT assay,scratch test,transwell assay and flow cytometry were performed to evaluate the effect of overexpression of mi R-542-5p on cell proliferation,migration,invasion and cel1 apoptosis of SKOV3 cell line.3. To predict and screen the target genes of mi R-542-5p using the bioinformatics softwares,and using RT-PCR、western blot techniques and dual luciferase report system for validation.Results:1. The expression of mi R-542-5p in serous ovarian cancer tissues was significantly down-regulated than in normal fimbriated of the distal fallopian tissues(P<0.05).There was no significant correlation was found between mi R-542-5p expression and clinicopathological features in serous ovarian cancer(P>0.05).2. The ability of proliferation of SKOV3 cells was significantly decreased compared with the negetive control group and parental SKOV3 cell group after overexpression of mi R-542-5p(P<0.05);transwell and scratch tests indicated that after overexpression of mi R-542-5p,the invasion and migration ability of SKOV3 cells were significantly decreased than the negetive control group(P<0.05);flow cytometry showed that the apoptosis rate of SKOV3 cells was increased after overexpression of mi R-542-5p compared with the negetive control group, but no effect was observed on cell cycle.3. We chose Ywhab as the target gene of mi R-542-5p using the bioinformatics softwares.RT-PCR showed that the content of Ywhab in SKOV3 cell lines is significantly decreased compared with the negetive control group and parental SKOV3 cell group after overexpression of mi R-542-5p.Western-blot analysis shows that the expression of Ywhab protein is decreases compared with the negetive control group in the cells which has transfected mi R-542-5p mimics.Dual luciferase report system indicated that mi R-542-5p significantly suppressed the relative luciferase activity of the reporter containing wild-type 3’-UTR but not the mutant reporter.Conclusions:1. mi R-542-5p may participate in the origination of serous ovarian cancer as a tumor-suppressor,and it has potential significance for the early diagnosis and treatment ofovarian cancer.2. The proliferation,migration and invasion of SKOV3 cell lines can be inhibited and the apoptosis rate can be increased by increasing the expression of mi R-542-5p.Our results indicate that mi R-542-5p may play an important role in the malignant progression of ovarian cancer.3. Ywhab is one of the target genes of mi R-542-5p,it can regulate and control the expression of Ywhab protein binding with its 3’-UTR after transcription.