How to explain the contradiction of microRNA 200c expression and survival in solid tumors? A meta-analysis

Identification and Validation of Circulating Micrornas as Prognostic Biomarkers in Pancreatic Ductal Adenocarcinoma Patients Undergoing Surgical Resection

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal and aggressive cancers with a less than 6% five-year survival rate. Circulating microRNAs (miRNAs) are emerging as a useful tool for non-invasive diagnosis and prognosis estimation in the various cancer types, including PDAC. Our study aimed to evaluate whether miRNAs in the pre-operative blood plasma specimen have the potential to predict the prognosis of PDAC patients. In total, 112 PDAC patients planned for surgical resection were enrolled in our prospective study. To identify prognostic miRNAs, we used small RNA sequencing in 24 plasma samples of PDAC patients with poor prognosis (overall survival (OS) < 16 months) and 24 plasma samples of PDAC patients with a good prognosis (OS > 20 months). qPCR validation of selected miRNA candidates was performed in the independent cohort of PDAC patients (n = 64). In the discovery phase of the study, we identified 44 miRNAs with significantly different levels in the plasma samples of the group of good and poor prognosis patients. Among these miRNAs, 23 showed lower levels, and 21 showed higher levels in plasma specimens from PDAC patients with poor prognosis. Eleven miRNAs were selected for the validation, but only miR-99a-5p and miR-365a-3p were confirmed to have significantly lower levels and miR-200c-3p higher levels in plasma samples of poor prognosis cases. Using the combination of these 3-miRNA levels, we were able to identify the patients with poor prognosis with sensitivity 85% and specificity 80% (Area Under the Curve = 0.890). Overall, 3-miRNA prognostic score associated with OS was identified in the pre-operative blood plasma samples of PDAC patients undergoing surgical resection. Following further independent validations, the detection of these miRNA may enable identification of PDAC patients who have no survival benefit from the surgical treatment, which is associated with the high morbidity rates.

Clinical Impact of Epithelial-to-Mesenchymal Transition Regulating MicroRNAs in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive carcinoma entities worldwide with early and rapid dissemination. Recently, we discussed the role of microRNAs as epigenetic regulators of Epithelial-to-Mesenchymal Transition (EMT) in PDAC. In this study, we investigated their value as diagnostic and prognostic markers in tissue and blood samples of 185 patients including PDAC, non-malignant pancreatic disorders, and age-matched healthy controls. Expression of the microRNA-200-family (microRNAs -141, -200a, -200b, -200c, -429) and microRNA-148a was significantly downregulated in tissue of PDAC Union internationale contre le cancer (UICC) Stage II. Correspondingly, stromal PDAC tissue showed strong expression of Fibronectin, Vimentin, and ZEB-1 (Zinc finger E-box-binding homeobox) versus low expression of E-cadherin. Transient transfection of microRNA-200b and microRNA-200c mimics resulted in the downregulation of their key target ZEB-1. Inversely, blood serum analyses of patients with PDAC UICC Stages II, III, and IV showed a significant over-expression of microRNA-200-family members, microRNA-148a, microRNA-10b, and microRNA-34a. Correspondingly, Enzyme-linked Immunosorbent Assay (ELISA) analyses revealed a significant over-expression of soluble E-cadherin in serum samples of PDAC patients versus healthy controls. The best diagnostic accuracy to distinguish between PDAC and non-PDAC in this patient collective could be achieved in tissue by microRNA-148a with an area under the receiver-operating-characteristic (ROC) curve (AUC) of 0.885 and in blood serum by a panel of microRNA-141, -200b, -200c, and CA.19-9 with an AUC of 0.890. Both diagnostic tools outreach the diagnostic performance of the currently most common diagnostic biomarker CA.19-9 (AUC of 0.834). Kaplan Meier survival analysis of this patient collective revealed an improved overall survival in PDAC patients with high expression of tissue-related microRNA-34a, -141, -200b, -200c, and -429. In conclusion, EMT-regulating microRNAs have great potential as liquid and solid biopsy markers in PDAC patients. Their prognostic and therapeutic benefits remain important tasks for future studies.

Identification of serum miR-139-3p as a non-invasive biomarker for colorectal cancer

Aberrant levels of circulating microRNAs are potential biomarkers for the early detection of colorectal cancer. The aim of this study was to study miR-139-3p and miR-622 in serum as a non-invasive biomarker for colorectal cancer diagnosis. We applied quantitative polymerase chain reaction to determine the levels of miR-139-3p and miR-622 in 42 pairs of tumor and adjacent non-tumor tissues, and in serum samples of 117 patients and 90 control subjects. Our results showed that miR-139-3p was silenced whereas miR-622 was overexpressed in colorectal cancer. Similarly, serum miR-139-3p level was significantly lower in colorectal cancer patients than in control subjects whereas miR-622 was more frequently detectable in patients. ROC analysis showed that AUC of miR-139-3p was 0.9935, with a sensitivity of 96.6% and specificity of 97.8%. Serum miR-139-3p level showed high sensitivity and specificity for both early and late stage CRCs and proximal and distal CRCs. Detectable serum miR-622 showed a sensitivity of 87.5% and specificity of 63.5% for discriminating CRC patients, but the sensitivity dropped for late stage patients (72.7%). We also included analyses of the blood CEA level for comparing the diagnostic performance of these blood-based biomarkers. The median level in CRC patients (3.6 ng/ml) was significantly higher than that in control (1.8 ng/ml). The AUC value of CEA in diagnosing CRC patients was 0.7515. CEA showed a positive correlation with tumor stage and age of patients and its level was higher in male. Collectively, serum miR-139-3p has strong potential as a promising non-invasive biomarker in colorectal cancer detection.

Upregulation of miR‑185 promotes apoptosis of the human gastric cancer cell line MGC803

MicroRNA (miR)-185, which has been reported to be abnormally expressed in some types of cancer, exerts significant effects on the proliferation, apoptosis, drug resistance and metastasis of cancer cells. The present study aimed to explore the effects and underlying molecular mechanisms of miR‑185 upregulation on the apoptosis of gastric cancer (GC) cells. Quantitative polymerase chain reaction (qPCR) and western blotting were used to detect the expression levels of miR‑185 in GC and adjacent normal tissues. In addition, miR‑185 expression was detected in the following GC cell lines: MKN74, SGC7901, BGC823, MGC803, as well as in the gastric epithelial cell line GES‑1. Subsequently, miR‑185 mimics were transfected into MGC803 cells. Post‑transfection, the following experiments were conducted: MTT assay was applied to test cell viability; flow cytometry (FCM) was used to determine the apoptotic rate of the cells; and qPCR and western blotting were conducted to detect the expression levels of the following apoptosis‑associated factors: B‑cell lymphoma 2 (Bcl‑2), Bcl‑2‑associated X protein (Bax), survivin, X‑linked inhibitor of apoptosis protein (XIAP), livin, caspase‑3 and caspase‑8. The results demonstrated that miR‑185 was downregulated in GC tissues compared with the adjacent tissues. In cell lines, miR‑185 expression was higher in GES‑1 cells compared with in the GC cell lines; in the 4 GC cell lines, the strongest miR‑185 expression was in MKN74 cells, followed by SGC7901 and BGC823 cells, and the weakest was in MGC803 cells (P<0.05). Expression of miR‑185 was associated with tumor size, differentiation and lymphatic metastasis. Post-transfection with miR‑185 mimics, miR‑185 expression was significantly increased in a time‑ and concentration‑dependent manner. MGC803 cell viability was significantly decreased following miR‑185 mimics transfection. The results of FCM demonstrated that post‑transfection with miR‑185 mimics, the apoptotic rate of MGC803 cells was significantly increased. Post‑transfection with miR‑185 mimics, the expression levels of Bcl‑2, survivin and XIAP were significantly decreased in MGC803 cells, whereas the expression levels of Bax and livin were not altered, and caspase‑3 and caspase‑8 expression was significantly increased. Spectrophotometry indicated that caspase‑3 and caspase‑8 activity was significantly increased in MGC803 cells following transfection with miR‑185 mimics. In conclusion, the present study suggested that miR‑185 upregulation in GC cells may promote apoptosis of tumor cells via gene expression regulation.

MicroRNA-17 family as novel biomarkers for cancer diagnosis: a meta-analysis based on 19 articles

Cancer remains as the leading cause of death all over the world due to the lack of efficient diagnostic techniques and therapeutic methods. Many studies have reported the potential diagnostic value of microRNA-17 (miRNA-17, miR-17) family members as biomarkers for cancer detection. However, inconsistent results were revealed from a wide range of studies. As a result of this, a meta-analysis based on 19 studies was conducted to assess the diagnostic performance of miR-17 family for cancer detection. A total of 1772 patients with certain types of cancer and 1320 healthy controls were involved in these studies. The overall diagnostic accuracy was measured by the following: sensitivity, 0.67 (95 % confidence interval (CI) 0.60-0.74); specificity, 0.83 (95 % CI 0.74-0.85); positive likelihood ratio (PLR), 3.9 (95 % CI 2.6-5.9); negative likelihood ratio (NLR), 0.40 (95 % CI 0.34-0.48); and diagnostic odds ratio (DOR), 10 (95 % CI 6-16), respectively. Additionally, the pooled area under the summary receiver operator characteristic (SROC) curve (area under the curve (AUC)) was 0.79 (95 % CI 0.75-0.82), indicating a relatively low accuracy of miR-17 family as biomarkers for cancer detection. Subgroup analysis further showed that miR-17 family had more reliable performance in cancer diagnosis for Asian than that for Caucasian. Moreover, multiple miRNAs containing miR-17, -20a/b, and -93 reflected higher diagnostic accuracy than both miR-106a/b (single miRNA) and the overall miR-17 family assay. Therefore, appropriate combinations of miR-17 family may be used as non-invasive screening biomarkers for cancer, and it is necessary to carry out a large-scale population-based study to further assess the potential diagnostic value of miR-17 family.

Prognostic Role of MicroRNA-200c-141 Cluster in Various Human Solid Malignant Neoplasms

The miR-200 family has emerged recently as a noticeable marker for predicting cancer prognosis and tumor progression. We aimed to review the evidence of miR-200c-141 genomic cluster as prognostic biomarkers in cancers. The results suggested that high level of miR-200c had no significant impact on OS (HR = 1.14 [0.77-1.69], P = 0.501) and DFS/PFS (HR = 0.72 [0.45-1.14], P = 0.161). Stratified analyses revealed that high miR-200c expression was significantly related to poor OS in serum/plasma (HR = 2.12 [1.62-2.77], P = 0.000) but not in tissues (HR = 0.89 [0.58-1.37], P = 0.599). High miR-200c expression was significantly associated with favorable DFS/PFS in tissues (HR = 0.56 [0.43-0.73], P = 0.000) but worse DFS/PFS in serum/plasma (HR = 1.90 [1.08-3.36], P = 0.027). For miR-141, we found that high miR-141 expression predicted no significant impact on OS (HR = 1.18 [0.74-1.88], P = 0.482) but poor DFS/PFS (HR = 1.11 [1.04-1.20], P = 0.003). Similarly, subgroup analyses showed that high miR-141 expression predicted poor OS in serum/plasma (HR = 4.34 [2.30-8.21], P = 0.000) but not in tissues (HR = 1.00 [0.92-1.09], P = 0.093). High miR-141 expression was significantly associated with worse DFS/PFS in tissues (HR = 1.12 [1.04-1.20], P = 0.002) but not in serum/plasma (HR = 0.90 [0.44-1.83], P = 0.771). Our findings indicated that, compared to their tissue counterparts, the expression level of miR-200c and miR-141 in peripheral blood may be more effective for monitoring cancer prognosis. High miR-141 expression was better at predicting tumor progression than survival for malignant tumors.

Expression of serum miR-200a, miR-200b, and miR-200c as candidate biomarkers in epithelial ovarian cancer and their association with clinicopathological features

BACKGROUND

MicroRNAs (miRs) have been implicated in the etiology of various human cancers. The aim of this study was to investigate the association of the expression of three members--miR 200a, miR 200b, and miR 200c belonging to the miR-200 family with clinicopathological characteristics and their impact on the progression of epithelial ovarian cancer (EOC).

MATERIALS AND METHODS

Total RNA from serum was isolated by Trizol method, polyadenylated, and reverse transcribed into cDNA. Expression levels of miR-200a, miR-200b, and miR-200c were detected by using miRNA qRT-PCR. We measured miR expression in 70 serum samples of EOC patients with matched controls using U6 snRNA as a reference. Levels of miR expression was compared with distinct clinicopathological features.

RESULTS

Expression of miR-200a was found to be greater than six-fold (p = 0.01), miR-200b and miR-200c greater than three-fold (p = 0.01) in comparison with matched normal controls. Association of miRNA expression with clinicopathological factors and progression was statistically evaluated. The expression levels of miR-200a and miR-200c were found to be significantly associated with disease progression (p = 0.04 and p < 0.001, respectively). miR-200a overexpression was found be associated with tumor histology and stage. Patients with lymph node metastasis showed significant elevation of miR-200c (p = 0.006). The AUC in ROC curve also indicated that serum levels of miR-200a and miR-200c might be worthwhile as a diagnostic tool in the near future.

CONCLUSION

Our findings suggest that miR-200a, miR-200b, and miR-200c overexpressions are associated with the aggressive tumor progression and be recognized as reliable markers to predict the prognosis and survival in EOC patients.

Regulatory network of microRNAs, target genes, transcription factors and host genes in endometrial cancer

Genes and microRNAs (miRNAs) have important roles in human oncology. However, most of the biological factors are reported in disperse form which makes it hard to discover the pathology. In this study, genes and miRNAs involved in human endometrial cancer(EC) were collected and formed into regulatory networks following their interactive relations, including miRNAs targeting genes, transcription factors (TFs) regulating miRNAs and miRNAs included in their host genes. Networks are constructed hierarchically at three levels: differentially expressed, related and global. Among the three, the differentially expressed network is the most important and fundamental network that contains the key genes and miRNAs in EC. The target genes, TFs and miRNAs are differentially expressed in EC so that any mutation in them may impact on EC development. Some key pathways in networks were highlighted to analyze how they interactively influence other factors and carcinogenesis. Upstream and downstream pathways of the differentially expressed genes and miRNAs were compared and analyzed. The purpose of this study was to partially reveal the deep regulatory mechanisms in EC using a new method that combines comprehensive genes and miRNAs together with their relationships. It may contribute to cancer prevention and gene therapy of EC.