Locus Summary

Gene:MIRLET7C; microRNA let-7c
Aliases: LET7C, let-7c, MIRNLET7C, hsa-let-7c
Summary:microRNAs (miRNAs) are short (20-24 nt) non-coding RNAs that are involved in post-transcriptional regulation of gene expression in multicellular organisms by affecting both the stability and translation of mRNAs. miRNAs are transcribed by RNA polymerase II as part of capped and polyadenylated primary transcripts (pri-miRNAs) that can be either protein-coding or non-coding. The primary transcript is cleaved by the Drosha ribonuclease III enzyme to produce an approximately 70-nt stem-loop precursor miRNA (pre-miRNA), which is further cleaved by the cytoplasmic Dicer ribonuclease to generate the mature miRNA and antisense miRNA star (miRNA*) products. The mature miRNA is incorporated into a RNA-induced silencing complex (RISC), which recognizes target mRNAs through imperfect base pairing with the miRNA and most commonly results in translational inhibition or destabilization of the target mRNA. The RefSeq represents the predicted microRNA stem-loop. [provided by RefSeq, Sep 2009]
Databases:miRBase, OMIM, HGNC, Ensembl, GeneCard, Gene
Source:NCBIAccessed: 13 March, 2017

Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 13 March 2017 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

Tag cloud generated 13 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (7)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

MicroRNA Function

Numbers shown below represent number of publications held in OncomiRDB database for Oncogenic and Tumor-Suppressive MicroRNAs.

TissueTarget Gene(s)Regulator(s)MIRLET7C Function in CancerEffect
liver (3)
-hepatocellular carcinoma (2)
-hepatocellular cancer stem cells (1)
SOCS1 (1)
BCL2L1 (1)
CASP3 (1)
IL6 (1)
TWIST1 (1)
inhibit cell proliferation (1)
induce cell cycle G1 arrest (1)
inhibit chemosensitivity (1)
promote sorafenib-induced apoptosis (1)
tumor-suppressive (2)
prostate (2)
-prostate cancer (2)
decrease cell proliferation (1)
decrease clonogenicity (1)
decrease anchorage-independent cell growth (1)
inhibit cell proliferation (1)
inhibit AR signaling (1)
tumor-suppressive (2)
blood (1)
-acute myeloid leukemia (1)
5088 (1)
promote granulocytic differentiation (1)

Source: OncomiRDB Wang D. et al. Bioinformatics 2014, 30(15):2237-2238.

Latest Publications: MIRLET7C (cancer-related)

Knyazev EN, Fomicheva KA, Mikhailenko DS, et al.
Plasma Levels of hsa-miR-619-5p and hsa-miR-1184 Differ in Prostatic Benign Hyperplasia and Cancer.
Bull Exp Biol Med. 2016; 161(1):108-11 [PubMed] Related Publications
Peripheral blood plasma profiles of circulating microRNA expression were analyzed in patients with prostatic cancer and benign hyperplasia. In prostatic cancer, significant increase in hsa-miR-619-5p and hsa-miR-1184 microRNA expression and significant decrease in hsalet-7b-5p and hsa-let-7c-5p microRNA expression were observed. The role of the relationship between the microRNA expression and the activities and functions of host genes with introns encoding these microRNA is discussed.

Liu Z, Cheng C, Luo X, et al.
CDK4 and miR-15a comprise an abnormal automodulatory feedback loop stimulating the pathogenesis and inducing chemotherapy resistance in nasopharyngeal carcinoma.
BMC Cancer. 2016; 16:238 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: In previous investigation, we reported that stably knocking down cyclin-dependent kinase 4(CDK4) induced expression of let-7c, which further suppressed cell cycle transition and cell growth by modulating cell cycle signaling in nasopharyngeal carcinoma (NPC). In this study, we further explored the molecular function and mechanism of CDK4 modulating miRNAs to stimulate cell cycle transition, cell growth, and Cisplatin (DDP) -resistance on in NPC.
METHODS: We identified changes in miRNAs by miRNA array and real-time PCR and the effect on DDP after knocking down CDK4 in NPC cells. Further, we investigated the molecular mechanisms by which CDK4 modulated miR-15a in NPC. Moreover, we also explored the role of miR-15a and the effect on DDP in NPC. Finally, we analyzed the correlation of miR-15a and CDK4 expression in NPC tissues.
RESULTS: In addition to let-7 family members, we observed that upregulated expression of miR-15a was significantly induced in CDK4-suppressed NPC cells. Further, we found that knocking down CDK4 suppressed c-Myc expression, and the latter directly suppressed the expression of miR-15a in NPC. Furthermore, miR-15a as a tumor suppressor antagonized CDK4 repressing cell cycle progression and cell growth in vitro and in vivo and induced the sensitivity of cells to DDP by regulating the c-Myc/CCND1/CDK4/E2F1 pathway in NPC. Finally, miR-15a was negatively weak correlated with the expression of CDK4 in NPC.
CONCLUSIONS: Our studies demonstrate that CDK4 and miR-15a comprise an abnormal automodulatory feedback loop stimulating the pathogenesis and inducing chemotherapy resistance in NPC.

Sun X, Xu C, Tang SC, et al.
Let-7c blocks estrogen-activated Wnt signaling in induction of self-renewal of breast cancer stem cells.
Cancer Gene Ther. 2016; 23(4):83-9 [PubMed] Related Publications
Let-7 miRNAs are involved in carcinogenesis and tumor progression through their roles in maintaining differentiation and normal development. However, there is little research focusing on the effects of let-7 on Wnt-activated self-renewal of breast cancer stem cells. By analyzing the expression levels of let-7 family members in clinical tissues, we found that higher expression levels of let-7b and let-7c were correlated with better clinical prognosis of patients with estrogen receptor (ER)α-positive breast tumor. Further, we found that only let-7c was inversely correlated with ERα expression, and there is corelationship between let-7c and Wnt signaling in clinical tissues. Aldehyde dehydrogenase (ALDH)1 sorting and mammosphere formation assays showed that let-7c inhibited the self-renewal of stem cells in ERα-positive breast cancer. Let-7c decreased ERα expression through directly binding to the 3'UTR (untranslated region), and let-7c inhibited the estrogen-induced activation of Wnt signaling. Depletion of ERα abolished let-7c functions in stem cell signatures, which further confirmed that let-7c inhibited estrogen-induced Wnt activity through decreasing ERα expression. Taken together, our findings identified a biochemical and functional link between let-7c with ERα/Wnt signaling in breast cancer stem cells.

Majer A, Blanchard AA, Medina S, et al.
Claudin 1 Expression Levels Affect miRNA Dynamics in Human Basal-Like Breast Cancer Cells.
DNA Cell Biol. 2016; 35(7):328-39 [PubMed] Related Publications
Deemed a putative tumor suppressor in breast cancer, the tight junction protein claudin 1 has now been shown to be highly expressed in the basal-like molecular subtype. Moreover, recent in vitro studies show that claudin 1 can regulate breast cancer cell motility and proliferation. Herein, we investigated whether microRNA (miRNA) dysregulation is associated with alterations in the level of claudin 1. Using next-generation sequencing (NGS), we identified seven miRNAs (miR-9-5p, miR-9-3p, let-7c, miR-127-3p, miR-99a-5p, miR-129-5p, and miR-146a-5p) that were deregulated as a consequence of claudin 1 overexpression in the MDA-MB231 human breast cancer (HBC) cell line. Most of these miRNAs have been associated with tumor suppression in a variety of cancers, including breast cancer. Moreover, through gene expression profiling analysis, we identified epithelial-mesenchymal transition-related genes, including platelet-derived growth factor receptor-beta (PDGFRB) and cadherin 1 (CDH1, E cadherin), whose downregulation correlated with claudin 1 overexpression. Collectively, we show for the first time that in HBC, claudin 1 can alter the dynamics of a number of miRNAs involved in tumor progression. Our data suggest that the dysregulated expression of these miRNAs, in conjunction with the high claudin 1 levels, could serve as a useful biomarker that identifies a subset of tumors within the poorly characterized basal-like subtype of breast cancer. Further studies are warranted to determine the role of these miRNAs in facilitating the function of claudin 1 in breast cancer.

Zhan M, Wen F, Liu L, et al.
JMJD1A promotes tumorigenesis and forms a feedback loop with EZH2/let-7c in NSCLC cells.
Tumour Biol. 2016; 37(8):11237-47 [PubMed] Related Publications
Lung cancer is the most common cause of cancer-related deaths worldwide, and non-small cell lung cancer (NSCLC) accounts for 80 to 85 % of all lung cancer. Although the standard treatment regimen has been established, long-term survival for NSCLC patients is still generally poor. The histone demethylase Jumonji domain containing 1A (JMJD1A) has been proposed as an oncogene in several types of human cancer, but its clinical significance and functional roles in NSCLC remain largely unclear. In the present study, JMJD1A was frequently upregulated in NSCLC compared with para-carcinoma tissues. JMJD1A knockdown significantly inhibited NSCLC cell growth, migration, and invasion in vitro and tumorigenesis in vivo. Further experiments demonstrated that JMJD1A knockdown could decrease the expression of EZH2, which has been shown to play a crucial role in the carcinogenesis of NSCLC and, in turn, increase the expression of anti-tumor microRNA let-7c. Also, let-7c directly targeted the 3'-untranslated regions of JMJD1A and EZH2. Taken together, JMJD1A could promote NSCLC tumorigenesis. JMJD1A/EZH2/let-7c constituted a feedback loop and might represent a promising therapeutic target for NSCLC.

Fassan M, Saraggi D, Balsamo L, et al.
Let-7c down-regulation in Helicobacter pylori-related gastric carcinogenesis.
Oncotarget. 2016; 7(4):4915-24 [PubMed] Free Access to Full Article Related Publications
Aberrant let-7c microRNA (miRNA) expression has been observed in Helicobacter pylori-related gastric cancer (GC) but fragmentary information is available on the let-7c dysregulation occurring with each phenotypic change involved in gastric carcinogenesis. Let-7c expression was assessed (qRT-PCR) in a series of 175 gastric biopsy samples representative of the whole spectrum of phenotypic changes involved in H. pylori-related gastric oncogenesis including: i) normal gastric mucosa, as obtained from dyspeptic controls (40 biopsy samples); ii) non-atrophic gastritis (40 samples); iii) atrophic-metaplastic gastritis (35 samples); iv) intra-epithelial neoplasia (30 samples); v) GC (30 samples). Let-7c expression was also tested in 20 biopsy samples obtained from 10 patients before and after H. pylori eradication therapy (median follow-up: 10 weeks; range: 7-14). The results obtained were further validated by in situ hybridization on multiple tissue specimens obtained from 5 surgically treated H. pylori-related GCs. The study also included 40 oxyntic biopsy samples obtained from serologically/histologically confirmed autoimmune gastritis (AIG: 20 corpus-restricted, non-atrophic; 20 corpus-restricted, atrophic-metaplastic). Let-7c expression dropped from non-atrophic gastritis to atrophic-metaplastic gastritis, intra-epithelial neoplasia, and invasive GC (p<0.001). It rose again significantly following H. pylori eradication (p=0.009). As in the H. pylori model, AIG also featured a significant let-7c down-regulation (p<0.001). The earliest phases of the two pathways to gastric oncogenesis (H. pylori-environmental and autoimmune host-related) are characterized by similar let-7c dysregulations. In H. pylori infection, let-7c down-regulation regresses after the bacterium's eradication, while it progresses significantly with the increasing severity of the histological lesions.

Ozcan O, Kara M, Yumrutas O, et al.
MTUS1 and its targeting miRNAs in colorectal carcinoma: significant associations.
Tumour Biol. 2016; 37(5):6637-45 [PubMed] Related Publications
Deregulated microRNA (miRNA) expression has been shown to be involved in the pathogenesis of several types of cancers including colorectal cancer (CRC). Thus, determining miRNA targets of genes that play critical role in the malignant transformation is very important. Here, expression levels of tumor suppressor microtubule-associated tumor suppressor 1 (MTUS1) and its regulatory miRNAs were reported. Predicted and validated targets of MTUS1 gene was determined by a computational approach. Expressions of MTUS1 and miRNAs were determined by using 96.96 Dynamic Array™ integrated fluidic circuit (Fluidigm). As a result, MTUS1 levels were found to be diminished in formalin-fixed, paraffin-embedded (FFPE) tissue samples of CRC patients compared to controls. Also, several of MTUS1 targeting miRNAs were found to be upregulated in CRC samples (miR-373-3p, 183-5p, 142-5p, 200c-3p, 19a-3p, -20a-5p, -181a-5p, -184, -181d-5p, -372-3p, 27b-3p, 98-5p, -let-7i-5p, -let-7d-5p, -let-7g-5p, -let-7b-5p, and -let-7c-5p). Of these miRNAs, miR-135b-5p, -373-3p, 183-5p, 142-5p, 200c-3p, 19a-3p showed marked expression levels. In contrast, expression levels of let-7a-5p, 7e-5p, 7f-5p, hsa-miR-125a-5p, and 125b-5p were found to be downregulated in CRC tissues. Accordingly, some of the overexpressed miRNAs especially the miR-135b-5p, -373-3p, 183-5p, 142-5p, 200c-3p, and 19a-3p may play key roles in CRC pathophysiology through MTUS1. In contrast, let-7a-5p, 7e-5p, 7f-5p, miR-125a-5p, and 125b-5p may play important roles in CRC carcinogenesis independent from the MTUS1. In conclusion, MTUS1 targeting miRNAs may play key roles in the development of CRC by downregulating tumor suppressor MTUS1.

Selvi RB, Swaminathan A, Chatterjee S, et al.
Inhibition of p300 lysine acetyltransferase activity by luteolin reduces tumor growth in head and neck squamous cell carcinoma (HNSCC) xenograft mouse model.
Oncotarget. 2015; 6(41):43806-18 [PubMed] Free Access to Full Article Related Publications
Chromatin acetylation is attributed with distinct functional relevance with respect to gene expression in normal and diseased conditions thereby leading to a topical interest in the concept of epigenetic modulators and therapy. We report here the identification and characterization of the acetylation inhibitory potential of an important dietary flavonoid, luteolin. Luteolin was found to inhibit p300 acetyltransferase with competitive binding to the acetyl CoA binding site. Luteolin treatment in a xenografted tumor model of head and neck squamous cell carcinoma (HNSCC), led to a dramatic reduction in tumor growth within 4 weeks corresponding to a decrease in histone acetylation. Cells treated with luteolin exhibit cell cycle arrest and decreased cell migration. Luteolin treatment led to an alteration in gene expression and miRNA profile including up-regulation of p53 induced miR-195/215, let7C; potentially translating into a tumor suppressor function. It also led to down-regulation of oncomiRNAs such as miR-135a, thereby reflecting global changes in the microRNA network. Furthermore, a direct correlation between the inhibition of histone acetylation and gene expression was established using chromatin immunoprecipitation on promoters of differentially expressed genes. A network of dysregulated genes and miRNAs was mapped along with the gene ontology categories, and the effects of luteolin were observed to be potentially at multiple levels: at the level of gene expression, miRNA expression and miRNA processing.

Bo LJ, Wei B, Li ZH, et al.
Bioinformatics analysis of miRNA expression profile between primary and recurrent glioblastoma.
Eur Rev Med Pharmacol Sci. 2015; 19(19):3579-86 [PubMed] Related Publications
OBJECTIVE: Glioblastoma (GBM) is the most malignant brain tumor with rapid relapse. The goal of this study is to identify microRNAs (miRNAs) involved in recurrent GBM.
MATERIALS AND METHODS: miRNA transcription profile data (GSE32466) were downloaded, including 12 primary GBM samples and 12 recurrent GBM samples. Then, limma package was utilized to identify differentially expressed miRNAs (DEMs) with the criteria of false discovery rate < 0.05 and |log2 fold change| ≥ 1. Thereafter, miTarget and TargetScan databases were used to predict the potential target genes of DEMs. Regulatory co-expression network was constructed based on co-expressed genes and potential miRNA-gene pairs, and then, pathway analysis was conducted. Furthermore, database miRWalk was used to screen out known GBM-associated miRNAs from the identified DEMs.
RESULTS: A total of 71 DEMs were identified between primary and recurrent GBM samples, and 2684 potential target genes were found. Besides, regulatory co-expression network was constructed, including 12 DEMs and 81 potential target genes. These genes significantly enriched in ECM-receptor interaction, ribosome, and focal adhesion pathways, and DEMs like hsa-miR-320a, hsa-miR-139-5p, has-miR-128, hsa-miR-140-5p, and hsa-miR-146b-5p had high degree. Notably, 7 DEMs in network were known GBM-associated miRNAs recorded in database miRWalk.
CONCLUSIONS: DEMs like hsa-miR-320a, hsa-miR-139-5p, has-miR-128, hsa-miR-146b-5p, hsa-let-7c, hsa-miR-128, and hsa-let-7a might participate in recurrent GBM. These results would pave ways for further study of recurrent GBM mechanism, and for the prevention and treatment of recurrent GBM. However, more experimental verifications are required to prove these predictions.

Han H, Du Y, Zhao W, et al.
PBX3 is targeted by multiple miRNAs and is essential for liver tumour-initiating cells.
Nat Commun. 2015; 6:8271 [PubMed] Related Publications
Tumour-initiating cells (TICs) are advocated to constitute the sustaining force to maintain and renew fully established malignancy; however, the molecular mechanisms responsible for these properties are elusive. We previously demonstrated that voltage-gated calcium channel α2δ1 subunit marks hepatocellular carcinoma (HCC) TICs. Here we confirm directly that α2δ1 is a HCC TIC surface marker, and identify let-7c, miR-200b, miR-222 and miR-424 as suppressors of α2δ1(+) HCC TICs. Interestingly, all the four miRNAs synergistically target PBX3, which is sufficient and necessary for the acquisition and maintenance of TIC properties. Moreover, PBX3 drives an essential transcriptional programme, activating the expression of genes critical for HCC TIC stemness including CACNA2D1, EpCAM, SOX2 and NOTCH3. In addition, the expression of CACNA2D1 and PBX3 mRNA is predictive of poor prognosis for HCC patients. Collectively, our study identifies an essential signalling pathway that controls the switch of HCC TIC phenotypes.

Tao J, Yang X, Li P, et al.
Identification of circulating microRNA signatures for upper tract urothelial carcinoma detection.
Mol Med Rep. 2015; 12(5):6752-60 [PubMed] Free Access to Full Article Related Publications
The involvement of circulating microRNAs (miRNAs) in cancer and their potential as diagnostic and prognostic biomarkers are becoming increasingly known. However, the significance of circulating miRNAs in upper tract urothelial carcinoma (UTUC) has remained to be investigated. The present study performed a genome‑wide serum miRNA analysis using a deep sequencing platform for initial screening. Subsequently, serum samples of 46 UTUC patients and 30 cancer‑free individuals with hematuria were subjected to a quantitative reverse‑transcription polymerase chain reaction analysis. The expression of thirteen miRNAs (miR‑664a‑3p, miR‑423‑5p, miR‑431‑5p, miR‑191‑5p, miR‑92a‑3p, miR‑22‑3p, miR‑26a‑5p, miR‑33b‑3p, miR‑16‑5p, let‑7a‑5p, let‑7b‑5p, let‑7f‑5p and let‑7c) was significantly different in serum from UTUC patients compared with that in control samples. Receiver operator characteristic analysis showed that 10 miRNAs (miR‑664a‑3p, miR‑431‑5p, miR‑423‑5p, miR‑191‑5p, miR‑33b‑3p, miR‑26a‑5p, miR‑22‑3p, miR‑16‑5p, let‑7b‑5p and let‑7c) had the potential to distinguish individuals with UTUC from the controls (areas under the curve >0.8). The present study provided the first evidence for the potential use of circulating miRNAs as biomarkers for UTUC diagnosis, which remains to be verified by further studies.

Humeau M, Vignolle-Vidoni A, Sicard F, et al.
Salivary MicroRNA in Pancreatic Cancer Patients.
PLoS One. 2015; 10(6):e0130996 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Pancreatic cancer is the fourth leading cause of cancer death in Western countries, with the lowest 1-year survival rate among commonly diagnosed cancers. Reliable biomarkers for pancreatic cancer diagnosis are lacking and are urgently needed to allow for curative surgery. As microRNA (miRNA) recently emerged as candidate biomarkers for this disease, we explored in the present pilot study the differences in salivary microRNA profiles between patients with pancreatic tumors that are not eligible for surgery, precancerous lesions, inflammatory disease or cancer-free patients as a potential early diagnostic tool.
METHODS: Whole saliva samples from patients with pancreatic cancer (n = 7), pancreatitis (n = 4), IPMN (n = 2), or healthy controls (n = 4) were obtained during endoscopic examination. After total RNA isolation, expression of 94 candidate miRNAs was screened by q(RT)PCR using Biomark Fluidgm. Human-derived pancreatic cancer cells were xenografted in athymic mice as an experimental model of pancreatic cancer.
RESULTS: We identified hsa-miR-21, hsa-miR-23a, hsa-miR-23b and miR-29c as being significantly upregulated in saliva of pancreatic cancer patients compared to control, showing sensitivities of 71.4%, 85.7%, 85,7% and 57%, respectively and excellent specificity (100%). Interestingly, hsa-miR-23a and hsa-miR23b are overexpressed in the saliva of patients with pancreatic cancer precursor lesions. We found that hsa-miR-210 and let-7c are overexpressed in the saliva of patients with pancreatitis as compared to the control group, with sensitivity of 100% and 75%, and specificity of 100% and 80%, respectively. Last hsa-miR-216 was upregulated in cancer patients as compared to patients diagnosed with pancreatitis, with sensitivity of 50% and specificity of 100%. In experimental models of PDAC, salivary microRNA detection precedes systemic detection of cancer cells markers.
CONCLUSIONS: Our novel findings indicate that salivary miRNA are discriminatory in pancreatic cancer patients that are not eligible for surgery. In addition, we demonstrate in experimental models that salivary miRNA detection precedes systemic detection of cancer cells markers. This study stems for the use of salivary miRNA as biomarker for the early diagnosis of patients with unresectable pancreatic cancer.

Malta M, Ribeiro J, Monteiro P, et al.
Let-7c is a Candidate Biomarker for Cervical Intraepithelial Lesions: A Pilot Study.
Mol Diagn Ther. 2015; 19(3):191-6 [PubMed] Related Publications
BACKGROUND: Numerous studies have been performed to discover predictive/prognostic biomarkers for human papillomavirus (HPV) infection and cervical cancer development. More recently, microRNAs were suggested as possible biomarkers of HPV-associated cancers and our aim was to characterize the expression of let-7c in exfoliated cervical cells from women with cervical intraepithelial lesions.
METHODS: Let-7c expression was evaluated by quantitative reverse transcription-polymerase chain reaction in 73 women with normal or cervical intraepithelial lesions: normal epithelium with (n = 17) and without (n = 21) HPV infection; low-grade squamous intraepithelial lesions (n = 14); and high-grade squamous intraepithelial lesions (n = 21).
RESULTS: Data showed a trend to down-regulation in women with low-grade squamous intraepithelial lesions (2(-ΔΔCt) = 0.38, p = 0.06) and a significant decreased expression of let-7c in women with low-grade squamous intraepithelial lesions (2(-ΔΔCt) = 0.21; p = 0.004). The combined analysis of all cervical intraepithelial lesions revealed a down-regulation of let-7c expression (2(-ΔΔCt) = 0.27; p = 0.011).
CONCLUSION: Our results showed that let-7c expression is significantly changed in the different cervical intraepithelial lesions and its levels should be further investigated as a possible biomarker for cervical intraepithelial lesions using exfoliated cervical cells as the sample source.

Tong HX, Zhou YH, Hou YY, et al.
Expression profile of microRNAs in gastrointestinal stromal tumors revealed by high throughput quantitative RT-PCR microarray.
World J Gastroenterol. 2015; 21(19):5843-55 [PubMed] Free Access to Full Article Related Publications
AIM: To investigate the microRNA (miRNA) expression profile in gastrointestinal stromal tumor (GIST) tissues that could serve as a novel diagnostic biomarker for GIST detection.
METHODS: We performed a quantitative real-time quantitative reverse transcriptase polymerase chain reaction assay to analyze the expression of 1888 miRNAs in a sample set that included 54 GIST tissue samples.
RESULTS: We found that dysregulation of several miRNAs may be related to the malignant potential of GISTs. Six of these miRNAs, hsa-let-7c, miR-218, miR-488#, miR-4683, miR-34c-5p and miR-4773, were selected as the final list of biomarkers to separate the malignant GISTs (M group) from the benign GISTs (B group). In addition, MiR-29b-2#, hsa-let-7c, miR-891b, miR-218, miR-204, miR-204-3p, miR-628-5p, miR-744, miR-29c#, miR-625 and miR-196a were used to distinguish between the borderline (BO group) and M groups. There were 11 common miRNAs selected to separate the benign and borderline (BB) group from the M group, including hsa-let-7c, miR-218, miR-628-5p, miR-204-3p, miR-204, miR-891b, miR-488#, miR-145, miR-891a, miR-34c-5p and miR-196a.
CONCLUSION: The identified miRNAs appear to be novel biomarkers to distinguish malignant from benign GISTs, which may be helpful to understand the mechanisms of GIST oncogenesis and progression, and to further elucidate the characteristics of GIST subtypes.

Zhou H, Tang K, Xiao H, et al.
A panel of eight-miRNA signature as a potential biomarker for predicting survival in bladder cancer.
J Exp Clin Cancer Res. 2015; 34:53 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: There is increasing evidence to suggest that miRNAs play an important role in predicting cancer survival. To identify a panel of miRNA signature that can divided tumor from normal bladder using miRNA expression levels, and to assess the prognostic value of this specific miRNA markers in bladder cancer (BCa).
METHODS: A comprehensive meta-review of published miRNA expression profiles that compared BCa and adjacent normal tissues was performed to determine candidate miRNAs as prognostic biomarkers for BCa. Vote-counting strategy and Robust Rank Aggregation method were used to identify significant meta-signature miRNAs.
RESULTS: We identified an eight-miRNA signature including three upregulated (miR-141, miR-200c, miR-21) and five downregulated (miR-145, miR-125, miR-199a, let-7c and miR-99a) miRNAs for the prediction of overall survival (OS) using TCGA dataset, and validated in our 48 BCa patients. X-tile plot was used to generate the optimum cut-off point and Kaplan-Meier method was used to calculate OS. A linear prognostic model of eight miRNAs was constructed and weighted by the importance scores from the supervised principal component method to divide patients into high- and low-risk groups. Patients assigned to the high-risk group were associated with poor OS compared with patients in the low-risk group (HR = 5.21, p < 0.001). Our validation cohort of 48 patients confirmed the panel of 8-miRNAs as a reliable prognostic tool for OS in patients with BCa (HR = 5.04, p < 0.001).
CONCLUSION: The present meta-analysis identified eight highly significant and consistently dysregulated miRNAs from 19 datasets. We also constructed an eight-miRNA signature which provided predictive and prognostic value that complements traditional clinicopathological risk factors.

Xu Z, Yu YQ, Ge YZ, et al.
MicroRNA expression profiles in muscle-invasive bladder cancer: identification of a four-microRNA signature associated with patient survival.
Tumour Biol. 2015; 36(10):8159-66 [PubMed] Related Publications
Bladder cancer ranks the second most common genitourinary tract cancer, and muscle-invasive bladder cancer (MIBC) accounts for approximately 25 % of all bladder cancer cases with high mortality. In the current study, with a total of 202 treatment-naïve primary MIBC patients identified from The Cancer Genome Atlas dataset, we comprehensively analyzed the genome-wide microRNA (miRNA) expression profiles in MIBC, with the aim to investigate the relationship of miRNA expression with the progression and prognosis of MIBC, and generate a miRNA signature of prognostic capabilities. In the progression-related miRNA profiles, a total of 47, 16, 3, and 84 miRNAs were selected for pathologic T, N, M, and histologic grade, respectively. Of the eight most important progression-related miRNAs, four (let-7c, mir-125b-1, mir-193a, and mir-99a) were significantly associated with survival of patients with MIBC. Finally, a four-miRNA signature was generated and proven as a promising prognostic parameter. In summary, this study identified the specific miRNAs associated with the progression and aggressiveness of MIBC and a four-miRNA signature as a promising prognostic parameter of MIBC.

Peng J, Mo R, Ma J, Fan J
let-7b and let-7c are determinants of intrinsic chemoresistance in renal cell carcinoma.
World J Surg Oncol. 2015; 13:175 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Renal cell carcinoma (RCC) is characterized by inherent resistance to chemotherapy. Earlier studies demonstrated that microRNAs (miRNAs) might be involved in the chemosensitivity of cancers. MicroRNA let-7, a putative tumor suppressor, is dysregulated in many cancers. Our study aims to investigate the exact role of let-7 in chemotherapy sensitivity of 5-fluorouracil (5-FU) in RCC.
METHODS: The clinical significance of let-7b and let-7c expression in surgically resected specimens was assessed by qRT-PCR. Cell proliferation assay and colony formation assay were used to assess the survival of 786-O cells treated with let-7b or let-7c combined with 5-FU. Western blot was used to detect the expression of Akt2 and caspase-7. Luciferase assay was used to detect the direct binding of let-7b and let-7c to the 3'-untranslated region (UTR) of Akt2.
RESULTS: Expression of let-7b and let-7c was significantly decreased in 32 paired clear cell renal cell carcinoma tissue specimens and the dysregulation of let-7b was associated with pathological grade. Transfection of let-7b or let-7c combined with 5-FU inhibited proliferation and potentiated the antitumor efficacies of 5-FU at tolerated concentration. let-7b and let-7c suppressed the luciferase activity of reporter plasmid containing the 3'-UTR of Akt2. Overexpression of let-7b and let-7c reduced Akt2 expression, and Akt2 inhibition enhanced the sensitivity to 5-FU by affecting apoptotic pathway.
CONCLUSIONS: Expression of let-7b and let-7c was frequently decreased in clear cell renal cell carcinoma tissues. The dysregulation of let-7b and let-7c may be involved in chemoresistance of RCC cells to 5-FU by down-regulating Akt2.

Zhu X, Wu L, Yao J, et al.
MicroRNA let-7c Inhibits Cell Proliferation and Induces Cell Cycle Arrest by Targeting CDC25A in Human Hepatocellular Carcinoma.
PLoS One. 2015; 10(4):e0124266 [PubMed] Free Access to Full Article Related Publications
Down-regulation of the microRNA let-7c plays an important role in the pathogenesis of human hepatocellular carcinoma (HCC). The aim of the present study was to determine whether the cell cycle regulator CDC25A is involved in the antitumor effect of let-7c in HCC. The expression levels of let-7c in HCC cell lines were examined by quantitative real-time PCR, and a let-7c agomir was transfected into HCC cells to overexpress let-7c. The effects of let-7c on HCC proliferation, apoptosis and cell cycle were analyzed. The in vivo tumor-inhibitory efficacy of let-7c was evaluated in a xenograft mouse model of HCC. Luciferase reporter assays and western blotting were conducted to identify the targets of let-7c and to determine the effects of let-7c on CDC25A, CyclinD1, CDK6, pRb and E2F2 expression. The results showed that the expression levels of let-7c were significantly decreased in HCC cell lines. Overexpression of let-7c repressed cell growth, induced cell apoptosis, led to G1 cell cycle arrest in vitro, and suppressed tumor growth in a HepG2 xenograft model in vivo. The luciferase reporter assay showed that CDC25A was a direct target of let-7c, and that let-7c inhibited the expression of CDC25A protein by directly targeting its 3' UTR. Restoration of CDC25A induced a let-7c-mediated G1-to-S phase transition. Western blot analysis demonstrated that overexpression of let-7c decreased CyclinD1, CDK6, pRb and E2F2 protein levels. In conclusion, this study indicates that let-7c suppresses HCC progression, possibly by directly targeting the cell cycle regulator CDC25A and indirectly affecting its downstream target molecules. Let-7c may therefore be an effective therapeutic target for HCC.

Liu WJ, Xu Q, Sun LP, et al.
Expression of serum let-7c, let-7i, and let-7f microRNA with its target gene, pepsinogen C, in gastric cancer and precancerous disease.
Tumour Biol. 2015; 36(5):3337-43 [PubMed] Related Publications
This study examined the expression patterns of serum let-7 microRNA (miRNA) and its target gene, pepsinogen C (PGC), in gastric cancer (GC) and precancerous disease patients to evaluate their diagnostic efficiency for GC and its precursor and to investigate any correlation between the two. Serum samples were taken from 638 patients, including 214 GC patients, 222 atrophic gastritis (AG) patients, and 202 controls (CON). The expression of serum let-7 miRNA was detected in control-AG (precancerous disease) through to GC patients using quantitative reverse-transcription polymerase chain reaction. Serum PGC was determined by enzyme-linked immuno-sorbent assay. PGC expression in situ was detected by immunohistochemistry staining. The luciferase reporter gene system was used to verify correlation between let-7 miRNA and its predicted target gene. The results showed that serum let-7c, let-7i, and let-7f demonstrated significant differences in the CON-AG-GC sequence (P = 0.017, P < 0.001, P = 0.003, respectively); let-7c was significantly lower in the AG group, and let-7i and let-7f were significantly higher in the GC group. Significantly different expressions of serum PGC were found among the three diseases, and also between AG vs. CON, and GC vs. CON (P = 0.027, P = 0.001, respectively). Linear-regression analysis suggested that serum let-7c was negatively correlated to the expression of PGC (r = -0.096, P = 0.047), and serum let-7c, let-7i, and let-7f showed no association with PGC expression in tissue. In addition, serum let-7c, let-7f, and let-7i showed significant correlations with environment factors. Serum let-7c, let-7i, and let-7f demonstrated significant differences in the CON-AG-GC disease sequence indicating that let-7 miRNA might have value by serving as potential biomarker in the diagnosis of GC or its precancerous diseases. There were significant negative correlations between serum let-7c and its target gene PGC expression.

Kachakova D, Mitkova A, Popov E, et al.
Combinations of serum prostate-specific antigen and plasma expression levels of let-7c, miR-30c, miR-141, and miR-375 as potential better diagnostic biomarkers for prostate cancer.
DNA Cell Biol. 2015; 34(3):189-200 [PubMed] Free Access to Full Article Related Publications
In the current study, expression levels of let-7c, miR-30c, miR-141, and miR-375 in plasma from 59 prostate cancer (PC) patients with different clinicopathological characteristics and two groups of controls: 16 benign prostatic hyperplasia (BPH) samples and 11 young asymptomatic men (YAM) were analyzed to evaluate their diagnostic and prognostic value in comparison to prostate-specific antigen (PSA). miR-375 was significantly downregulated in 83.5% of patients compared to BPH controls and showed stronger diagnostic accuracy (area under the curve [AUC]=0.809, 95% CI: 0.697-0.922, p=0.00016) compared with PSA (AUC=0.710, 95% CI: 0.559-0.861, p=0.013). Expression levels of let-7c showed potential to distinguish PC patients from BPH controls with AUC=0.757, but the result did not reach significance. Better discriminating performance was observed when combinations of studied biomarkers were used. Sensitivity of 86.8% and specificity of 81.8% were reached when all biomarkers were combined (AUC=0.877) and YAM were used as calibrators. None of the studied microRNAs (miRNAs) showed correlation with clinicopathological characteristics. PSA levels were significantly correlated with the Gleason score, tumor stage, and lymph node metastasis with Spearman correlation coefficients: 0.612, 0.576, and 0.458. In conclusion, the combination of the studied circulating plasma miRNAs and serum PSA has the potential to be used as a noninvasive diagnostic biomarker for PC screening outperforming the PSA testing alone.

Dip N, Reis ST, Abe DK, et al.
Micro RNA expression and prognosis in low-grade non-invasive urothelial carcinoma.
Int Braz J Urol. 2014 Sep-Oct; 40(5):644-9 [PubMed] Related Publications
PURPOSE: To analyze a possible correlation between a miRNA expression profile and important prognostic factors for pTa urothelial carcinomas (UC), including tumor size, multiplicity and episodes of recurrence.
MATERIALS AND METHODS: Thirty low-grade non-invasive pTa bladder UC from patients submitted to transurethral resection were studied, in a mean follow-up of 17.7 months. As controls, we used normal bladder tissue from five patients submitted to retropubic prostatectomy to treat benign prostatic hyperplasia. Extraction, cDNA and amplification were performed for 14 miRNAs (miR-100, -10a, -21, -205, -let7c, -143, -145, -221, -223, -15a, -16, -199a and -452) using specific kits, and RNU-43 and -48 were used as endogenous controls. Statistical tests were used to compare tumor size, multiplicity and episodes of recurrence with miRNAs expression profiles.
RESULTS: There was a marginal correlation between multiplicity and miR-let7c over-expression. For all others miRNA no correlation between their expression and prognostic factors was found.
CONCLUSION: We did not find differences for miRNAs expression profiles associated with prognostic factors in tumor group studied. The majority of miRNAs are down-regulated, except mir-10a, over-expressed in most of cases, seeming to have increased levels as tumor with more unfavorable prognostic factors. More studies are needed in order to find a miRNA profile able to provide prognosis in pTa UC to be used in clinical practice.

Barzon L, Cappellesso R, Peta E, et al.
Profiling of expression of human papillomavirus-related cancer miRNAs in penile squamous cell carcinomas.
Am J Pathol. 2014; 184(12):3376-83 [PubMed] Related Publications
Penile squamous cell carcinoma (PSCC) is a rare tumor associated with high-risk human papillomavirus (HR-HPV) infection in 30% to 60% of cases. Altered expression of miRNAs has been reported in HPV-related cervical and head and neck cancers, but such data have not been available for PSCC. We analyzed a series of 59 PSCCs and 8 condylomata for presence of HPV infection, for p16(INK4a), Ki-67, and p53 immunohistochemical expression, and for expression of a panel of cellular miRNAs (let-7c, miR-23b, miR-34a, miR-145, miR-146a, miR-196a, and miR-218) involved in HPV-related cancer. HR-HPV DNA (HPV16 in most cases) was detected in 17/59 (29%) PSCCs; all penile condylomata (8/8) were positive for low-risk HPV6 or HPV11. HR-HPV(+) PSCCs overexpressed p16(INK4a) in 88% cases and p53 in 35% of cases, whereas HR-HPV(-) PSCCs were positive for p16(INK4a) and p53 immunostaining in 9% and 44% of cases, respectively. Among the miRNAs investigated, expression of miR-218 was lower in PSCCs with HR-HPV infection and in p53(-) cancers. Hypermethylation of the promoter of the SLIT2 gene, which contains miR-218-1 in its intronic region, was frequently observed in PSCCs, mainly in those with low miR-218 expression. Epigenetic silencing of miR-218 is a common feature in HR-HPV(+) PSCCs and in HR-HPV(-) PSCCs without immunohistochemical detection of p53.

Escalera-Cueto M, Medina-Martínez I, del Angel RM, et al.
Let-7c overexpression inhibits dengue virus replication in human hepatoma Huh-7 cells.
Virus Res. 2015; 196:105-12 [PubMed] Related Publications
MicroRNAs (miRNAs) constitute an important class of non-coding RNA implicated in gene expression regulation. More than 1900 miRNA molecules have been identified in humans and their modulation during viral infection and it is recognized to play a role in latency regulation or in establishing an antiviral state. The liver cells are targets during DENV infection, and alteration of liver functions contributes to severe disease. In this work the miRNAs expression profile of the human hepatoma cell line, Huh-7, infected with DENV-2 was determined using microarray and real-time PCR. Let-7c is one of the miRNAs up-regulated during DENV infection in the hepatic Huh-7 as well as in the macrophage-monocytic cell line U937-DC-SIGN. Let-7c overexpression down-regulates both DENV-2 and DENV-4 infection. Additionally, we found that the transcription factor BACH1, a let-7c target, is also down-regulated during DENV infection. In accordance with this finding, HO-1, the main responsive factor of BACH1 was found up-regulated. The up-regulation of HO-1 may contribute to the stress oxidative response in infected cells.

Tsai KW, Hu LY, Chen TW, et al.
Emerging role of microRNAs in modulating endothelin-1 expression in gastric cancer.
Oncol Rep. 2015; 33(1):485-93 [PubMed] Related Publications
Endothelin-1 (ET-1) is a small 21-amino acid peptide that is known to exert diverse biological effects on a wide variety of tissues and cell types through its own receptors. The ET-1-ETRA axis is frequently dysfunctional in numerous types of carcinomas, and contributes to the promotion of cell growth and migration. microRNAs (miRNAs) are small non-coding RNAs that play a critical role in carcinogenesis through mRNA degradation or the translational inhibition of cancer-associated protein-coding genes. However, the role of ET-1 and the relationship between ET-1 and miRNAs in gastric cancer remain unknown. Results of the analysis of the database of The Cancer Genome Atlas (TCGA) revealed that ET-1 is significantly overexpressed in gastric cancer cells when compared with its expression in adjacent normal cells. Exogenous ET-1 significantly enhanced gastric cancer cell proliferation, implying that ET-1 plays an oncogenic role in gastric cancer carcinogenesis. Using a luciferase reporter assay we showed that 18 miRNA candidates had a significant silencing effect on ET-1 expression by up to 20% in HEK293T cells. Among them, 5 miRNAs (miR-1, miR-101, miR-125A, miR-144 and let-7c) were shown to be involved in ET-1 silencing through post-transcriptional modulation in gastric cancer. Our data also revealed that DNA hypermethylation contributes to the silenced miR-1 expression in gastric cancer cells. The ectopic expression of miR-1 significantly inhibited AGS cell proliferation by suppressing ET-1 expression. Overall, our study revealed that ET-1 overexpression may be due to DNA hypermethylation resulting in the silencing of miR-1 expression in gastric cancer cells. In addition, we identified several miRNAs as potential modulators for ET-1 in gastric cancer, which may be used as targets for gastric cancer therapy.

Bailey ST, Westerling T, Brown M
Loss of estrogen-regulated microRNA expression increases HER2 signaling and is prognostic of poor outcome in luminal breast cancer.
Cancer Res. 2015; 75(2):436-45 [PubMed] Free Access to Full Article Related Publications
Among the genes regulated by estrogen receptor (ER) are miRNAs that play a role in breast cancer signaling pathways. To determine whether miRNAs are involved in ER-positive breast cancer progression to hormone independence, we profiled the expression of 800 miRNAs in the estrogen-dependent human breast cancer cell line MCF7 and its estrogen-independent derivative MCF7:2A (MCF7:2A) using NanoString. We found 78 miRNAs differentially expressed between the two cell lines, including a cluster comprising let-7c, miR99a, and miR125b, which is encoded in an intron of the long noncoding RNA LINC00478. These miRNAs are ER targets in MCF7 cells, and nearby ER binding and their expression are significantly decreased in MCF7:2A cells. The expression of these miRNAs was interrogated in patient samples profiled in The Cancer Genome Atlas (TCGA). Among luminal tumors, these miRNAs are expressed at higher levels in luminal A versus B tumors. Although their expression is uniformly low in luminal B tumors, they are lost only in a subset of luminal A patients. Interestingly, this subset with low expression of these miRNAs had worse overall survival compared with luminal A patients with high expression. We confirmed that miR125b directly targets HER2 and that let-7c also regulates HER2 protein expression. In addition, HER2 protein expression and activity are negatively correlated with let-7c expression in TCGA. In summary, we identified an ER-regulated miRNA cluster that regulates HER2, is lost with progression to estrogen independence, and may serve as a biomarker of poor outcome in ER(+) luminal A breast cancer patients.

Xiong H, Li Q, Liu S, et al.
Integrated microRNA and mRNA transcriptome sequencing reveals the potential roles of miRNAs in stage I endometrioid endometrial carcinoma.
PLoS One. 2014; 9(10):e110163 [PubMed] Free Access to Full Article Related Publications
Endometrioid endometrial carcinoma (EEC) is the most dominant subtype of endometrial cancer. Aberrant transcriptional regulation has been implicated in EEC. Herein, we characterized mRNA and miRNA transcriptomes by RNA sequencing in EEC to investigate potential molecular mechanisms underlying the pathogenesis. Total mRNA and small RNA were simultaneously sequenced by next generation sequencing technology for 3 pairs of stage I EEC and adjacent non-tumorous tissues. On average, 52,716,765 pair-end 100 bp mRNA reads and 1,669,602 single-end 50 bp miRNA reads were generated. Further analysis indicated that 7 miRNAs and 320 corresponding target genes were differentially expressed in the three stage I EEC patients. Six of all the seven differentially expressed miRNAs were targeting on eleven differentially expressed genes in the cell cycle pathway. Real-time quantitative PCR in sequencing samples and other independent 21 pairs of samples validated the miRNA-mRNA differential co-expression, which were involved in cell cycle pathway, in the stage I EEC. Thus, we confirmed the involvement of hsa-let-7c-5p and hsa-miR-99a-3p in EEC and firstly found dysregulation of hsa-miR-196a-5p, hsa-miR-328-3p, hsa-miR-337-3p, and hsa-miR-181c-3p in EEC. Moreover, synergistic regulations among these miRNAs were detected. Transcript sequence variants such as single nucleotide variant (SNV) and short insertions and deletions (Indels) were also characterized. Our results provide insights on dysregulated miRNA-mRNA co-expression and valuable resources on transcript variation in stage I EEC, which implies the new molecular mechanisms that underlying pathogenesis of stage I EEC and supplies opportunity for further in depth investigations.

Ding CF, Chen WQ, Zhu YT, et al.
Circulating microRNAs in patients with polycystic ovary syndrome.
Hum Fertil (Camb). 2015; 18(1):22-9 [PubMed] Related Publications
AIM: To explore the pattern of expression of circulating miRNAs in patients with polycystic ovary syndrome (PCOS).
MATERIALS AND METHODS: Microarray and qRT-PCR were used to investigate circulating miRNAs in PCOS during clinical diagnosis. The targets of dys-regulated miRNAs were predicted using bioinformatics, followed by function and pathway analysis using the databases of Gene Ontology and the KEGG pathway.
RESULTS: BMI, triglyceride, HOMA-IR, Testosterone and CRP levels were significantly higher, while estradiol was significantly lower in PCOS than in control groups. After SAM analysis, 5 circulating miRNAs were significantly up-regulated (let-7i-3pm, miR-5706, miR-4463, miR-3665, miR-638) and 4 (miR-124-3p, miR-128, miR-29a-3p, let-7c) were down-regulated in PCOS patients. Hierarchical clustering showed a general distinction between PCOS and control samples in a heat map. After joint prediction by different statistical methods, 34 and 41 genes targeted were up-and down-regulated miRNAs, in PCOS and controls, respectively. Further, GO and KEGG analyses revealed the involvement of the immune system, ATP binding, MAPK signaling, apoptosis, angiogenesis, response to reactive oxygen species and p53 signaling pathways in PCOS.
CONCLUSIONS: We report a novel non-invasive miRNA profile which distinguishes PCOS patients from healthy controls. The miRNA-target database may provide a novel understanding of PCOS and potential therapeutic targets.

Kiss O, Tőkés AM, Spisák S, et al.
Breast- and salivary gland-derived adenoid cystic carcinomas: potential post-transcriptional divergencies. A pilot study based on miRNA expression profiling of four cases and review of the potential relevance of the findings.
Pathol Oncol Res. 2015; 21(1):29-44 [PubMed] Related Publications
Adenoid cystic carcinoma (ACC) is a malignant tumor of the salivary glands but identical tumors can also arise from the breast. Despite their similar histomorphological appearance the salivary gland- and the breast-derived forms differ in their clinical features: while ACC of the salivary glands (sACC) have an aggressive clinical course, the breast-derived form (bACC) shows a very favourable clinical outcome. To date no exact molecular alterations have yet been identified which would explain the diverse clinical features of the ACCs of different origin. In our pilot experiment we investigated the post-transcriptional features of ACC cases by performing microRNA-profiling on 2-2 bACC and sACC tissues and on 1-1 normal breast and salivary gland tissue. By comparing the microRNA-profiles of the investigated samples we identified microRNAs which were expressed differently in bACC and sACC cases according to their normal controls: 7 microRNAs were overexpressed in sACC cases and downexpressed in bACC tumors (let-7b, let-7c, miR-17, miR-20a, miR-24, miR-195, miR-768-3) while 9 microRNAs were downexpressed in sACC cases and overexpressed in bACC tissues (let-7e, miR-23b, miR-27b, miR-193b, miR-320a, miR-320c, miR-768-5p, miR-1280 and miR-1826) relative to their controls. We also identified 8 microRNAs which were only expressed in sACCs and one microRNA (miR-1234) which was only absent in sACC cases. By target predictor online databases potential targets of the these microRNAs were detected to identify genes that may play central role in the diverse clinical outcome of bACC and sACC cases.

Canturk KM, Ozdemir M, Can C, et al.
Investigation of key miRNAs and target genes in bladder cancer using miRNA profiling and bioinformatic tools.
Mol Biol Rep. 2014; 41(12):8127-35 [PubMed] Related Publications
Despite the association of several miRNAs with bladder cancer, little is known about the miRNAs' regulatory networks. In this study, we aimed to construct potential networks of bladder-cancer-related miRNAs and their known target genes using miRNA expression profiling and bioinformatics tools and to investigate potential key molecules that might play roles in bladder cancer regulatory networks. Global miRNA expression profiles were obtained using microarray followed by RT-qPCR validation using two randomly selected miRNAs. Known targets of deregulated miRNAs were utilized using DIANA-TarBase database v6.0. The incorporation of deregulated miRNAs and target genes into KEGG pathways were utilized using DIANA-mirPath software. To construct potential miRNA regulatory networks, the overlapping parts of three selected KEGG pathways were visualized by Cytoscape software. We finally gained 19 deregulated miRNAs, including 5 ups- and 14 down regulated in 27 bladder-cancer tissue samples and 8 normal urothelial tissue samples. The enrichment results of deregulated miRNAs and known target genes showed that most pathways were related to cancer or cell signaling pathways. We determined the hub CDK6, BCL2, E2F3, PTEN, MYC, RB, and ERBB3 target genes and hub hsa-let-7c, hsa-miR-195-5p, hsa-miR-141-3p, hsa-miR-26a-5p, hsa-miR-23b-3p, and hsa-miR-125b-5p miRNAs of the constructed networks. These findings provide new insights into the bladder cancer regulatory networks and give us a hypothesis that hsa-let-7c, hsa-miR-195-5p, and hsa-miR-125b-5p, along with CDK4 and CDK6 genes might exist in the same bladder cancer pathway. Particularly, hub miRNAs and genes might be potential biomarkers for bladder cancer clinics.

Björner S, Fitzpatrick PA, Li Y, et al.
Epithelial and stromal microRNA signatures of columnar cell hyperplasia linking Let-7c to precancerous and cancerous breast cancer cell proliferation.
PLoS One. 2014; 9(8):e105099 [PubMed] Free Access to Full Article Related Publications
Columnar cell hyperplasia (CCH) is the earliest histologically identifiable breast lesion linked to cancer progression and is characterized by increased proliferation, decreased apoptosis and elevated oestrogen receptor α (ERα) expression. The mechanisms underlying the initiation of these lesions have not been clarified but might involve early and fundamental changes in cancer progression. MiRNAs are key regulators of several biological processes, acting by influencing the post-transcriptional regulation of numerous targets, thus making miRNAs potential candidates in cancer initiation. Here we have defined novel epithelial as well as stromal miRNA signatures from columnar cell hyperplasia lesions compared to normal terminal duct lobular units by using microdissection and miRNA microarrays. Let-7c were among the identified downregulated epithelial miRNAs and its functions were delineated in unique CCH derived cells and breast cancer cell line MCF-7 suggesting anti-proliferative traits potentially due to effects on Myb and ERα. MiR-132 was upregulated in the stroma surrounding CCH compared to stoma surrounding normal terminal duct lobular units (TDLUs), and overexpression of miR-132 in immortalized fibroblasts and in fibroblasts co-cultured with epithelial CCH cells caused substantial expression changes of genes involved in metabolism, DNA damage and cell motility. The miRNA signatures identified in CCH indicate early changes in the epithelial and stromal compartment of CCH and could represent early key alterations in breast cancer progression that potentially could be targeted in novel prevention or treatment schedules.

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