Question: What is the relationship between serum miR-21 levels, clinicopathological factors, prognosis in ovarian cancer patients, and the role of miR-100?

Context:
["Finally, five promising differentially miRNAs (miR-200a, miR-100, miR-141, miR-200b, and miR-200c) were reported with the consistent direction in four or more studies. MiR-200a, miR-200b, miR-200c, and miR-141, all of them belong to miR-200 family, were reported with consistently up-regulated in at least 4 studies, whereas miR-100 was reported with down-regulated in 4 studies", "Upregulation of microRNA-203 is associated with advanced tumor progression and poor prognosis in epithelial ovarian cancer", "multivariate analysis showed that the status of miR-203 expression was an independent predictor for both overall survival and progression-free survival in EOC. These findings provide the convincing evidence for the first time that the upregulation of miR-203 may serve as a novel molecular marker to predict the aggressive tumor progression and unfavorable prognosis of EOC patients", "Some, but not all, of the data indicated that the miR-200 family was dysregulated in a variety of malignancies. In this study, we demonstrated that miR-200a and E-cadherin were significantly upregulated in EOC compared to benign epithelial ovarian cysts and normal ovarian tissues", "There was a significantly positive correlation between miR-200a and E-cadherin in EOC. The biphasic expression pattern suggested that miR-200a levels may serve as novel biomarkers for the early detection of EOC, and miR-200a and E-cadherin are candidate targets for the development of new treatment modalities against ovarian cancer", "Kaplan-Meier analysis showed low miR-510 expression, low miR-509-5p expression, and advanced FIGO stage, and chemotherapy resistance were significantly associated with poorer overall survival (P < 0.05). Our results suggest that miRNAs may play a role in the progression of OSC, and miR-510 and miR-509-5p may be considered novel-candidate clinical biomarkers for predicting OSC outcome", "The qRT-PCR results showed that miR-510, miR-509-5p, and miR-508-3p were significantly downregulated and that miR-483-5p was upregulated in stage III OSC compared with stage I, which was consistent with the microarray results", "In this study, we examined serum miR-21 levels in epithelial ovarian cancer (EOC) patients, and explored its association with clinicopathological factors and prognosis. The results showed significantly higher serum miR-21 levels in EOC patients than in healthy controls. In addition, increased serum miR-21 expression was correlated with advanced FIGO stage, high tumor grade, and shortened overall survival. These findings indicate that serum miR-21 may serve as a novel diagnostic and prognostic marker, and be used as a therapeutic target for the treatment of EOC", "Identification of serum microRNA-21 as a biomarker for early detection and prognosis in human epithelial ovarian cancer", "Serum miR-132, miR-26a, let-7b, and miR-145 could be considered as potential candidates as novel biomarkers in serous ovarian cancer.", "Among the miRNAs that showed a consistent regulation tendency through all specimens and showed more than a 2-fold difference in serum, 5 miRNAs (miR-132, miR-26a, let-7b, miR-145, and miR-143) were determined as the 5 most markedly down-regulated miRNAs in the serum from ovarian cancer patients with respect to those of controls. Four miRNAs (miR-132, miR-26a, let-7b, and miR-145) out of 5 selected miRNAs were significantly underexpressed in the serum of ovarian cancer patients in qRT-PCR", " microRNA (miR)-182, miR-200a, miR-200b and miR-200c were highly overexpressed in the SEOC cell lines relative to normal human ovarian surface epithelial cells and were assessed in RNA extracted from serum as candidate biomarkers", "Together, these results suggest that low miR-100 expression             may be an independent poor prognostic factor and miR-100 can function as a tumor             suppressor by targeting PLK1 in human EOCs", "Prognostic implications of microRNA-100 and its functional roles in             human epithelial ovarian cancer", "Taken together, miR-152 and miR-148a may be involved  

Answer: The relationship between serum miR-21 levels, clinicopathological factors, and prognosis in ovarian cancer patients is that increased serum miR-21 expression is correlated with advanced FIGO stage, high tumor grade, and shortened overall survival. Serum miR-21 may serve as a novel diagnostic and prognostic marker in epithelial ovarian cancer. On the other hand, miR-100 expression levels may be an independent poor prognostic factor and function as a tumor suppressor by targeting PLK1 in human EOCs.