hsa-miR-520h downregulates ABCG2 in pancreatic cancer cells to inhibit migration,invasion, and side populations

Background:

Expression of ABCG2 is normally absent or low in the pancreas, but high in human pancreatic cancer cells. The mechanism by which ABCG2 is altered in human cancers remains unknown.

Methods:

We investigated ABCG2 expression in four pancreatic cancer cell lines, and used three microRNA (miRNA) target prediction programmes, and information from the existing literature to predict and identify hsa-miR-520h as an miRNA that targets ABCG2. The function of this miRNA was investigated by transient transfection of the pancreatic cancer cell line PANC-1 with oligonucleotides that mimic hsa-miR-520h.

Results:

Results showed that both mRNA and protein levels of ABCG2 were reduced, indicating that it was a target of hsa-miR-520h. Introduction of hsa-miR-520h mimics into PANC-1 cells also resulted in inhibition of cell migration and invasion, and reduction of side population cells. Cell proliferation, cell cycle progression and apoptosis were not affected.

Conclusions:

We propose that the effects of hsa-miR-520h may be, at least in part, caused by its regulation of ABCG2. Thus, our findings provide a new insight into the function of miRNA in the regulation of ABCG2 expression in pancreatic cancer. Gene therapy using miRNA mimics may therefore be useful as a pancreatic cancer therapy.     

TGF-β1 alters microRNA profile in human gastric cancer cells

Objective: MicroRNAs (miRNAs) are important regulators that play a key role in tumorigenesis and tumor progression. Transforming growth factor-β1 (TGF-β1) is involved in invasion and metastasis in many tumors. In this study, we investigated the microRNAs (miRNA) profiles altered by TGF-β1 in gastric cancer (GC) cells. Methods: We detected the expression profiles of miRNA by miRNA microarray and quantitative real-time polymerase chain reaction. Migration and invasion, wound-healing assay, prediction of miRNA targets, Western blot and qRT-PCR analysis were carried out to determine the role of one selected miRNA, namely miR-193b, in affecting the biological behaviors of GC BGC823 cells. Results: Among 847 human miRNAs in the microarray, three miRNAs (miR-27a, miR-29b-1 and miR-194) were up-regulated and three (miR-574-3p, miR-193b and miR-130b) were down-regulated in BGC823 cells treated with TGF-β1 compared with control. miR-193b suppressed the invasion and metastasis of GC cells in vivo and in vitro, and down-regulated urokinase-type plasminogen activator (uPA) protein in GC cells. Conclusions: TGF-β1 altered miRNA expression profile in BGC823 cells. Among the altered miRNAs, TGF-β1 induced the down-regulation of miR-193b, which inhibited cell invasion and metastasis in vivo and in vitro, and down-regulated uPA protein in GC cells.     

Deregulated microRNAs in gastric cancer tissue-derived mesenchymal stem cells: novel biomarkers and a mechanism for gastric cancer

Background:

MicroRNAs (miRNAs) are involved in gastric cancer development and progression. However, the expression and role of miRNAs in gastric cancer stromal cells are still unclear.

Methods:

The miRNAs differentially expressed in gastric cancer tissue-derived mesenchymal stem cells (GC-MSCs) relative to adjacent non-cancerous tissue-derived MSCs (GCN-MSCs) and in cancer tissues relative to adjacent non-cancerous tissues were screened using miRNA microarray and validated by quantitative RT–PCR. The impact of GC-MSCs on HGC-27 cells was observed in vitro using colony formation and transwell assays, and these cells were subcutaneously co-injected into mice to assess tumour growth in vivo. Exogenous downregulation of miR-221 expression in cells was achieved using an miRNA inhibitor.

Results:

miR-214, miR-221 and miR-222 were found to be commonly upregulated in GC-MSCs and cancer tissues. Their levels were tightly associated with lymph node metastasis, venous invasion and the TNM stage. Gastric cancer tissue-derived mesenchymal stem cells significantly promoted HGC-27 growth and migration and increased the expression of miR-221 via paracrine secretion, and the targeted inhibition of miR-221 in GC-MSCs could block its tumour-supporting role. GC-MSC-derived exosomes were found to deliver miR-221 to HGC-27 cells and promoted their proliferation and migration.

Conclusions:

Gastric cancer tissue-derived mesenchymal stem cells favour gastric cancer progression by transferring exosomal miRNAs to gastric cancer cells, thus providing a novel mechanism for the role of GC-MSCs and new biomarkers for gastric cancer.     

The expression profile of microRNAs in a model of 7,12-dimethyl-benz[a]anthrance-induced oral carcinogenesis in Syrian hamster

Background

Non-coding RNA molecules, such as microRNAs, may play an important role in carcinogenesis. Recent studies have indicated that microRNAs are involved in initiation and progression of various malignancies. However, little work has been done to compare the microRNA expression patterns in oral cancer. In this study, we constructed an animal model of oral squamous cell carcinoma to investigate expression profiles of microRNAs in oral carcinogenesis.

Methods

The animal model of oral squamous cell carcinoma was conducted by tri-weekly (Monday, Wednesday, and Friday) painting with 5% DMBA in acetone. Six Syrian hamsters, including three from the treated group and three from the control group, were used as a training group for microRNA microarray analysis. All microarray data were analyzed by Significance Analysis of Microarrays (SAM) and CLUSTER 3.0 software, and this result was further confirmed by qRT-PCR assay.

Results

Seventeen microRNAs were differentially expressed in oral squamous cell carcinoma. Five microRNAs (hsa-miR-21, hsa-miR-200b, hsa-miR-221, hsa-miR-338, and mmu-miR-762) were significantly upregulated and twelve microRNAs (hsa-miR-16, hsa-miR-26a, hsa-miR-29a, hsa-miR-124a, hsa-miR-125b, mmu-miR-126-5p, hsa-miR-143, hsa-miR-145, hsa-miR-148b, hsa-miR-155, hsa-miR-199a, and hsa-miR-203) were down-regulated in cancer tissues. The expression levels of hsa-miR-21 and hsa-miR-16 seen with Stem-loop qRT-PCR were also seen in microarray analysis in all samples.

Conclusion

Our findings identified specific microRNA expression in oral squamous cell carcinoma and suggested that microRNAs have a role in oral carcinogenesis.     

miRNA profiling in metastatic renal cell carcinoma reveals a tumour-suppressor effect for miR-215

Background:

Renal cell carcinoma (RCC) is the most common neoplasm of the adult kidney. Metastatic RCC is difficult to treat. The 5-year survival rate for metastatic RCC is ⩽10%. Recently, microRNAs (miRNAs) have been shown to have a role in cancer metastasis and potential as prognostic biomarkers in cancer.

Method:

We performed a miRNA microarray to identify a miRNA signature characteristic of metastatic compared with primary RCCs. We validated our results by quantitative real-time PCR. We performed experimental and bioinformatic analyses to explore the involvement of miR-215 in RCC progression and metastasis.

Results:

We identified 65 miRNAs that were significantly altered in metastatic compared with primary RCCs. We validated our results by examining the expression of miR-10b, miR-126, miR-196a, miR-204 and miR-215, in two independent cohorts of patients. We showed that overexpression of miR-215 decreased cellular migration and invasion in an RCC cell line model. In addition, through gene expression profiling, we identified direct and indirect targets of miR-215 that can contribute to tumour metastasis.

Conclusion:

Our analysis showed that miRNAs are altered in metastatic RCCs and can contribute to kidney cancer metastasis through different biological processes. Dysregulated miRNAs represent potential prognostic biomarkers and may have therapeutic applications in kidney cancer.     

MiR-221/-222 differentiate prognostic groups in advanced breast cancers and influence cell invasion

Background:

MiR-221/-222 are frequently overexpressed in breast cancer and are associated with increased malignancy. The specific modification of microRNAs (miRNAs) expression could be a promising strategy in breast cancer therapy, leading to the suppression of tumourigenic processes in tumour cells.

Methods:

MiR-221/-222 expressions were analysed in 86 breast cancer tissues by quantitative RT–PCR and tested for correlation with immunohistochemistry data and clinical follow-up. In vitro assays were conducted using human breast cancer cell lines with lentiviral overexpression of miR-221/-222.

Results:

In tumour tissues, miR-221/-222 were associated with the occurrence of distant metastases. In particular, high levels of miR-221 were revealed to have a high prognostic impact for the identification of significantly different groups with advanced tumours. MiR-221/-222 overexpression strongly increased cell proliferation and invasion in vitro. Following miR-221/-222 overexpression an increased uPAR expression and cell invasion were observed.

Conclusion:

This study demonstrates a significant role for highly expressed miR-221/-222 in advanced breast cancers allowing for the identification of significantly different prognostic groups, particularly for HER2-positive and lymph-node-positive breast cancers. Considering that miR-221/-222 are strongly involved in cell invasion, these miRNAs may be promising markers for breast cancer prognosis and therapy.     

IL-22 produced by cancer-associated fibroblasts promotes gastric cancer cell invasion via STAT3 and ERK signaling

Background:

Interleukin-22 (IL-22) has been recently highlighted owing to its biological significance in the modulation of tissue responses during inflammation. However, the role of IL-22 in carcinogenesis has remained unclear. Here, we investigated the pathophysiological significance of IL-22 expression in gastric cancer tissues and examined the mechanism by which IL-22 promotes gastric cancer cell invasion.

Methods:

Human gastric cancer specimens were analysed by immunohistochemistry for expression of IL-22 and IL-22 receptor 1 (IL-22R1). The effects of IL-22-induced STAT3 and ERK signalling on invasive ability of gastric cancer cells were examined using a small-interfering RNA system and specific inhibitors. AGS cells were co-cultured with cancer-associated fibroblasts (CAFs) from human gastric cancer tissues and assessed by invasion assay.

Results:

Interleukin-22 and its receptor were expressed in α-smooth muscle actin-positive stromal cells and tumour cells at the invasive front of gastric cancer tissues, respectively. The expression of IL-22 and IL-22R1 was significantly related to lymphatic invasion. Interleukin-22 treatment promoted the invasive ability of gastric cancer cells through STAT3 and ERK activation. The invasive ability of gastric cancer cells was significantly enhanced by co-culture with IL-22-expressing CAFs.

Conclusions:

Interleukin-22 produced by CAFs promotes gastric cancer cell invasion via STAT3 and ERK signalling.     

Downregulation of SPARC expression decreases gastric cancer cellular invasion and survival

Background

Secreted protein acidic and rich in cysteine (SPARC) plays a key role in the development of many tissues and organ types. Aberrant SPARC expression was found in a wide variety of human cancers, contributes to tumor development. Because SPARC was found to be overexpressed in human gastric cancer tissue, we therefore to explore the expression of SPARC in gastric cancer lines and the carcinogenic mechanisms.

Methods

SPARC expression was evaluated in a panel of human gastric cancer cell lines. MGC803 and HGC 27 gastric cancer cell lines expressing high level of SPARC were transiently transfected with SPARC-specific small interfering RNAs and subsequently evaluated for effects on invasion and proliferation.

Results

Small interfering RNA-mediated knockdown of SPARC in MGC803 and HGC 27 gastric cancer cells dramatically decreased their invasion. Knockdown of SPARC was also observed to significantly increase the apoptosis of MGC803 and HGC 27 gastric cancer cells compared with control transfected group.

Conclusions

Our data showed that downregulating of SPARC inhibits invasion and growth of human gastric cancer cells. Thus, targeting of SPARC could be an effective therapeutic approach against gastric cancer.     

FAT4 functions as a tumour suppressor in gastric cancer by modulating Wnt/β-catenin signalling

Background:

FAT4, a cadherin-related protein, was shown to function as a tumour suppressor; however, its role in human gastric cancer remains largely unknown. Here, we investigated the role of FAT4 in gastric cancer and examined the underlying molecular mechanisms.

Methods:

The expression of FAT4 was evaluated by immunohistochemistry, western blotting, and qRT–PCR in relation to the clinicopathological characteristics of gastric cancer patients. The effects of FAT4 silencing on cell proliferation, migration, and invasion were assessed by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium) assay, and migration and invasion assays in gastric cancer cell lines in vitro and in a mouse xenograft model in vivo.

Results:

Downregulation of FAT4 expression in gastric cancer tissues compared with adjacent normal tissues was correlated with lymph-node metastasis and poor survival. Knockdown of FAT4 promoted the growth and invasion of gastric cancer cells via the activation of Wnt/β-catenin signalling, and induced epithelial-to-mesenchymal transition (EMT) in gastric cancer cells, as demonstrated by the upregulation and downregulation of mesenchymal and epithelial markers. Silencing of FAT4 promoted tumour growth and metastasis in a gastric cancer xenograft model in vivo.

Conclusions:

FAT4 has a tumour suppressor role mediated by the modulation of Wnt/β-catenin signalling, providing potential novel targets for the treatment of gastric cancer.     

miR-19a acts as an oncogenic microRNA and is up-regulated in bladder cancer

Background

The application of microRNAs (miRNAs) as potential biomarkers and therapy targets has been widely investigated in many kinds of cancers. The discovery of tumor associated miRNAs in serum of patients supported the use of plasma/serum miRNAs as noninvasive means of cancer detection. However, the aberrant expression of miRNAs in bladder cancer patients and their intensive roles and mechanisms in bladder cancer are poorly understood.

Methods

Taqman probe stem-loop real-time PCR was used to accurately measure the levels of miR-19a in bladder cancer cell lines, 100 pairs of bladder cancer tissues and the adjacent non-neoplastic tissues and also the plasma collected from bladder cancer patients and normal controls. miR-19a mimics and inhibitors were transfected into bladder cancer cells to investigate its role on regulating cell proliferation which was measured by CCK-8 and colony formation assay. The target of miR-19a was identified by western blot and whether its regulatory role depends on its target was improved by a rescue experiment with miR-19a mimic and PTEN expression plasmid.

Results

miR-19a was significantly up-regulated in bladder cancer tissues and high-level of miR-19a was correlative with more aggressive phenotypes of bladder cancer. Meanwhile, gain or loss of function of miR-19a demonstrated that miR-19a can promote cell growth of bladder cancer cells and the further mechanism studies indicated that its oncogenic role was dependent on targeting PTEN. Furthermore, investigation of miR-19a expression in the plasma of bladder cancer patients showed that miR-19a was also increased in plasma of bladder cancer patients which strongly supported miR-19a could be developed as potential diagnostic marker of bladder cancer.

Conclusions

Our data indicated that miR-19a might act as an oncogenic microRNA in bladder cancer and was significantly up-regulated in bladder cancer carcinogenesis. The oncogenic role of miR19a in bladder cancer was dependent on targeting PTEN.     

OTUB1 de-ubiquitinating enzyme promotes prostate cancer cell invasion in vitro and tumorigenesis in vivo

Background

Ubiquitination is a highly dynamic and reversible process with a central role in cell homeostasis. Deregulation of several deubiquitinating enzymes has been linked to tumor development but their specific role in prostate cancer progression remains unexplored.

Methods

RNAi screening was used to investigate the role of the ovarian tumor proteases (OTU) family of deubiquitinating enzymes on the proliferation and invasion capacity of prostate cancer cells. RhoA activity was measured in relation with OTUB1 effects on prostate cancer cell invasion. Tumor xenograft mouse model with stable OTUB1 knockdown was used to investigate OTUB1 influence in tumor growth.

Results

Our RNAi screening identified OTUB1 as an important regulator of prostate cancer cell invasion through the modulation of RhoA activation. The effect of OTUB1 on RhoA activation is important for androgen-induced repression of p53 expression in prostate cancer cells. In localized prostate cancer tumors OTUB1 was found overexpressed as compared to normal prostatic epithelial cells. Prostate cancer xenografts expressing reduced levels of OTUB1 exhibit reduced tumor growth and reduced metastatic dissemination in vivo.

Conclusions

OTUB1 mediates prostate cancer cell invasion through RhoA activation and promotes tumorigenesis in vivo. Our results suggest that drugs targeting the catalytic activity of OTUB1 could potentially be used as therapeutics for metastatic prostate cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-014-0280-2) contains supplementary material, which is available to authorized users.     

Identification of cardiac-related circulating microRNA profile in human chronic heart failure

Background

During chronic heart failure, levels of circulating miRNAs endued with characteristics of diseased cells could be identified as biomarkers. In this study, we sought to identify cardiac-related circulating miRNAs as biomarkers of failing heart.

Methods

Total RNA of plasma and heart samples was extracted from 10 normal controls and 14 patients with chronic heart failure. Microarray was applied for miRNA profiles. Validation and organ/tissue distribution analysis was performed by qRT-PCR. In addition, bioinformatics analysis was performed to understand the critical roles of these cardiac-related circulating miRNAs in heart failure.

Results

Results showed that levels of more than half of the miRNAs dysregulated in heart failed to show any differences in plasma. Meanwhile, more than 90% of the miRNAs dysregulated in plasma remained stable in heart. Four cardiac fibroblast-derived miRNAs (miR-660-3p, miR-665, miR-1285-3p and miR-4491) were found significantly upregulated in heart and plasma during heart failure. These 4 miRNAs strongly discriminated patients from controls, and 3 of them showed significant correlations with LVEF.

Conclusions

This study provides global profiles of miRNAs changes in plasma and failing heart, and using a circulation-tissue miRNA profiling comparison model, we successfully identify 3 cardiac-related circulating miRNAs as potential biomarkers for diagnosis of heart failure.     

Different miRNA signatures of oral and pharyngeal squamous cell carcinomas: a prospective translational study

Background:

MicroRNAs (miRNAs) are small non-coding RNAs, which regulate mRNA translation/decay, and may serve as biomarkers. We characterised the expression of miRNAs in clinically sampled oral and pharyngeal squamous cell carcinoma (OSCC and PSCC) and described the influence of human papilloma virus (HPV).

Methods:

Biopsies obtained from 51 patients with OSCC/PSCC and 40 control patients were used for microarray analysis. The results were correlated to clinical data and HPV status. Supervised learning by support vector machines was employed to generate a diagnostic miRNA signature.

Results:

One hundred and fourteen miRNAs were differentially expressed between OSCC and normal oral epithelium, with the downregulation of miR-375 and upregulation of miR-31 as the most significant aberrations. Pharyngeal squamous cell carcinoma exhibited 38 differentially expressed miRNAs compared with normal pharyngeal epithelium. Differences in the miRNA expression pattern of both normal epithelium and SCC were observed between the oral cavity compared with the pharynx. Human papilloma virus infection revealed perturbations of 21 miRNAs, most significantly in miR-127-3p and miR363. A molecular classifier including 61 miRNAs was generated for OSCC with an accuracy of 93%.

Conclusion:

MicroRNAs may serve as useful biomarkers in OSCC and PSCC. The influence of HPV on miRNA may provide a mechanism for the distinct clinical behaviour of HPV-infected tumours.     

A panel of eight-miRNA signature as a potential biomarker for predicting survival in bladder cancer

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.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-015-0167-0) contains supplementary material, which is available to authorized users.     

An ER-associated miRNA signature predicts prognosis in ER-positive breast cancer

Background

Breast cancer patients with positive estrogen receptor (ER) have a better prognosis. However, no prognostic miRNA signature was reported in the ER-positive breast cancer. The aim of the study was to identify and assess the prognostic significance of a miRNA signature in ER-positive breast cancer.

Methods

Two cohorts from The Cancer Genome Atlas (TCGA) dataset were used as training (n =596) and testing set (n =319). Differential expression profiling was identified in the training set. And the prognostic value of the miRNA signature was then assessed in the two cohorts.

Results

A total of 14 miRNAs were observed to be associated with the status of ER by significance analysis of microarrays (SAM) in the training set. Patients were characterized as high score or low score group according to the calculated risk scores from each miRNA. And patients in high score group had worse overall survival compared with those in low score group both in the training and testing set.

Conclusions

Our study revealed a miRNA signature including 14 miRNAs associated with ER status which could act as a prognostic marker in ER-positive breast cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-014-0094-5) contains supplementary material, which is available to authorized users.     

Differential expression of microRNAs during melanoma progression: miR-200c, miR-205 and miR-211 are downregulated in melanoma and act as tumour suppressors

Background:

The incidence of malignant melanoma is increasing faster than that for any other cancer. Histological examination of skin excision biopsies remains the standard method for melanoma diagnosis and prognosis. Significant morphological overlap between benign and malignant lesions complicates diagnosis, and tumour thickness is not always an accurate predictor of prognosis.

Methods:

To identify improved molecular markers to support histological examination, we used microarray analysis of formalin-fixed and paraffin-embedded samples from different stages of melanomagenesis to identify differentially expressed microRNAs (miRNAs). Differential expression was validated by qRT–PCR, and functional studies were carried out after transfection of miRNA precursors or inhibitors into melanoma cells to modulate miRNA expression.

Results:

In all, 20 miRNAs showed highly significant differential expression between benign naevi and either primary or metastatic melanomas, the majority being downregulated in melanoma, whereas only 2 miRNAs, namely miR-203 and miR-205, were differentially expressed between primary and metastatic melanomas. In functional in vitro assays, overexpression of miR-200c and miR-205 inhibited anchorage-independent colony formation and overexpression of miR-211 inhibited both anchorage-independent colony formation and invasion.

Conclusion:

We have identified a series of differentially expressed miRNAs that could be useful as diagnostic or prognostic markers for melanoma and have shown that three miRNAs (namely miR-200c, miR-205 and miR-211) act as tumour suppressors.     

Genistein downregulates onco-miR-1260b and inhibits Wnt-signalling in renal cancer cells

Background:

Wnt-signalling has an important role in renal cancer and it is modulated by genistein in other cancers. Recently, microRNAs (miRNAs) have emerged as new regulators of gene expression. Thus, we focused on miRNAs to examine the regulatory mechanism of genistein on the Wnt-signalling pathway in renal cell carcinoma (RCC).

Methods:

Initially, we investigated the effect of genistein on Wnt-signalling (TOPflash reporter assay (TCF reporter assays)) in renal cancer cells, and using microarray identified candidate miRNAs whose expression was decreased by genistein. We performed functional analyses and investigated the relationship between miRNA expression and renal cancer patient outcomes. We also did 3′UTR luciferase assays to look at direct miRNA regulation of Wnt-signalling-related genes.

Results:

Genistein promoted apoptosis while inhibiting RCC cell proliferation and invasion. Genistein also decreased TCF reporter activity in RCC cells. We found that miR-1260b was highly expressed and significantly downregulated by genistein in RCC cells. The expression of miR-1260b was significantly higher in renal cancer tissues compared with normal, and significantly related to overall shorter survival. In addition, miR-1260b promoted renal cancer cell proliferation and invasion in RCC cells. The 3′UTR luciferase activity of target genes (sFRP1, Dkk2, Smad4) was significantly decreased and their protein expression significantly upregulated in miR-1260b inhibitor-transfected renal cancer cells.

Conclusion:

Our data suggest that genistein inhibited Wnt-signalling by regulating miR-1260b expression in renal cancer cells.     

MicroRNA-106b promotes colorectal cancer cell migration and invasion by directly targeting DLC1

Background

Growing evidence suggests that microRNAs (miRNAs) play an important role in tumor development, progression and metastasis. Aberrant miR-106b expression has been reported in several cancers. However, the role and underlying mechanism of miR-106 in colorectal cancer (CRC) have not been addressed.

Methods

Quantitative RT-PCR(qRT-PCR) was performed to evaluate miR-106b levels in CRC cell lines and patient specimens. Cell proliferation was detected using MTT assay, and cell migration and invasion ability were evaluated by wound healing assay and transwell assay. The target gene of miR-106b was determined by qRT-PCR, western blot and luciferase assays.

Results

miR-106b was significantly up-regulated in metastatic CRC tissues and cell lines, and high miR-106b expression was associated with lymph node metastasis and advanced clinical stage. In addition, miR-106b overexpression enhances, whereas miR-106b depletion reduces CRC cell migration and invasion. Moreover, we identify DLC1 as a direct target of miR-106b, reveal its expression to be inversely correlated with miR-106b in CRC samples and show that its re-introduction reverses miR-106b-induced CRC cell migration and invasion. Furthermore, survival analyses showed the patients with high mi-106b/low DLC1 had shorter overall survival (OS) and disease-free survival (DFS) rates, and confirmed miR-106b may be an independent prognostic factor for OS and DFS in CRC patients.

Conclusions

Our findings indicate that miR-106b promotes CRC cell migration and invasion by targeting DLC1. This miRNA may serve as a potential prognostic biomarker and therapeutic target for CRC.