In the present study, the relative mRNA expression levels of miR-195 in cervical cancer tissues and corresponding adjacent normal tissues were detected. The result showed that miR-195 expression was significantly reduced in cervical cancer tissues compared with that in normal tissues at mRNA level. And its low expression was correlated with the development of cervical cancer. Moreover, we found that miR-195 expression was closely related to clinical outcome of this tumor.
Previous studies had demonstrated that some miRNAs were associated with tumorigenesis and development of various cancers [7, 15]. Due to the differences of target genes, these miRNAs could act as oncogenes or tumor suppressors in a various types of human tumors [16]. As a member of miRNAs, the abnormal expression of miR-195 was more commonly occurred in many cancers. Serum miR-195 was considered as a potential bio-marker for the diagnosis, therapy and prognosis of cancers [17, 18]. Moreover, Deng et al. mentioned that miR-195 expression was reduced in cell lines and tissues of gastric cancer, and inhibited tumor growth through epigenetical regulation in this tumor [19]. Decreased expression of miR-195 in cervical cancer cells and tissues was indicated to promote cell invasion and migration via targeting Smad3 [20]. These studies were consistent with our result, suggesting that miR-195 played a tumor suppressive role and exhibited tissue-specific in human tumors, including cervical cancer.
A large number of researches had indicated that over-expression of miR-195 could inhibit tumor cell proliferation, invasion and migration in vitro, implying that miR-195 was involved in tumor growth and metastasis, including cervical cancer [20-22]. However, the relationship between miR-195 and the progression of cervical cancer in clinical practice needs much further studies. In this study, a notable correlation was found between low miR-195 expression and advanced FIGO stage, positive lymph node metastasis and present vascular invasion which were some aggressive clinical characteristics representing advanced progression and metastasis of cancers. Our finding suggested that miR-195 expression was associated with the progression of cervical cancer. Similar results were observed in gastric cancer and osteosarcoma [23, 24]. Nevertheless, a study of Song et al. reported that miR-195 expression was strongly correlated with tumor size and histological grade, but not linked with tumor stage of colorectal cancer patients, which was inconsistent with our study [25]. The functions of miR-195 in the development of different cancers might be varied. Thus, given these limitations of sample size and its source, further studies are needed to explore the role of miR-195 in the progression of human tumors.
The prediction of clinical outcome of cervical cancer is very important to provide better therapeutic strategies for patients. FIGO stage and lymph node metastasis had been proven to be independent prognostic factors of cervical cancer [26]. They were indicated to be correlated with miR-195 expression in this study, suggesting that miR-195 might be related to the prognosis of cervical cancer. We found that patients with high expression of miR-195 tended to have longer overall survival than those with low miR-195 expression via Kaplan-Meier analysis. Univariate and multivariate analyses revealed miR-195 might have potency to be an independent factor for the prognosis of cervical cancer. A growing body of evidence had demonstrated that miR-195 expression was closely associated with the overall survival of human tumors, which was similar to our result [27, 28].