Antiviral effect of miR-206 in rainbow trout (Oncorhynchus mykiss) against infectious hematopoietic necrosis virus infection

Infectious hematopoietic necrosis (IHN), caused by IHN virus, is a highly contagious and lethal disease that seriously hampers the development of rainbow trout (Oncorhynchus mykiss) aquaculture. However, the immune response mechanism of rainbow trout underlying IHNV infection remains largely unknown. MicroRNAs act as post-transcriptional regulators of gene expression and perform a crucial role in fish immune response. Herein, the regulatory mechanism and function of miR-206 in rainbow trout resistance to IHNV were investigated by overexpression and silencing. The expression analysis showed that miR-206 and its potential target receptor-interacting serine/threonine-protein kinase 2 (RIP2) exhibited significant time-dependent changes in headkidney, spleen and rainbow trout primary liver cells infected with IHNV and their expression displayed a negative correlation. In vitro, the interaction between miR-206 and RIP2 was verified by luciferase reporter assay, and miR-206 silencing in rainbow trout primary liver cells markedly increased RIP2 and interferon (IFN) expression but significantly decreased IHNV copies, and opposite results were obtained after miR-206 overexpression or RIP2 knockdown. In vivo, overexpressed miR-206 with agomiR resulted in a decrease in the expression of RIP2 and IFN in liver, headkidney and spleen. This study revealed the key role of miR-206 in anti-IHNV, which provided potential for anti-viral drug screening in rainbow trout.

USF2 activates RhoB/ROCK pathway by transcriptional inhibition of miR-206 to promote pyroptosis in septic cardiomyocytes

Septic cardiomyopathy (SCM) is one of the most serious complications of sepsis. The present study investigated the role and mechanism of upstream stimulatory factor 2 (USF2) in SCM. Serum samples were extracted from SCM patients and healthy individuals. A murine model of sepsis was induced by caecal ligation and puncture (CLP) surgery. Myocardial injury was examined by echocardiography and HE staining. ELISA assay evaluated myocardial markers (CK-MB, cTnI) and inflammatory cytokines (TNF-α, IL-1β, IL-18). Primary mouse cardiomyocytes were treated with lipopolysaccharide (LPS) to simulate sepsis in vitro. RT-qPCR and Western blot were used for analyzing gene and protein levels. CCK-8 assay assessed cell viability. NLRP3 was detected by immunofluorescence. ChIP, RIP and dual luciferase reporter assays were conducted to validate the molecular associations. USF2 was increased in serum from SCM patients, septic mice and primary cardiomyocytes. USF2 silencing improved the survival of septic mice and attenuated sepsis-induced myocardial pyroptosis and inflammation in vitro and in vivo. Mechanistically, USF2 could directly bind to the promoter of miR-206 to transcriptionally inhibit its expression. Moreover, RhoB was confirmed as a target of miR-206 and could promote ROCK activation and NLRP3 inflammasome formation. Moreover, overexpression of RhoB remarkably reversed the protection against LPS-induced inflammation and pyroptosis mediated by USF2 deletion or miR-206 overexpression in cardiomyocytes. The above findings elucidated that USF2 knockdown exerted a cardioprotective effect on sepsis by decreasing pyroptosis and inflammation via miR-206/RhoB/ROCK pathway, suggesting that USF2 may be a novel drug target in SCM.

microRNA-206 prevents hepatocellular carcinoma growth and metastasis via down-regulating CREB5 and inhibiting the PI3K/AKT signaling pathway

Hepatocellular carcinoma (HCC) is one of the most common cancers and has continued to increase in incidence worldwide. Moreover, the involvement of microRNAs (miRs) has been reported in the development and progression of HCC. Here, we investigated the role of miR-206 in HCC growth and metastasis. HCC-related microarray datasets were harvested to screen differentially expressed miRNAs in HCC samples followed by prediction of downstream target genes. The dual-luciferase reporter assay verified the target-binding relationship between miR-206 and CREB5. The human HCC cell line MHCC97-H was cultured in vitro and transfected with miR-206 mimic/inhibitor or sh-/oe-CREB5 for analyzing MHCC97-H cell biological functions. The orthotopic xenograft model of HCC mice was constructed to observe the tumorigenic ability of HCC cells in vivo. Bioinformatics analysis found that miR-206 may be involved in HCC growth and metastasis by targeting CREB5 and regulating PI3K/AKT signaling pathway. In vivo animal experiments found that CREB5 was significantly overexpressed in mouse HCC tissues. In HCC cells, miR-206 can target down-regulate the expression of CREB5, thereby inhibiting the activation of PI3K/AKT signaling pathway. Furthermore, in vitro cell experiments confirmed that overexpression of miR-206 could inhibit the PI3K/AKT signaling pathway by down-regulating CREB5 expression, thereby inhibiting the proliferation, migration and invasion of HCC cells. In conclusion, our results revealed that miR-206 could down-regulate the expression of CREB5 and inhibit the activation of PI3K/AKT signaling pathway, thereby preventing HCC growth and metastasis.Abbreviations: HCC: hepatocellular carcinoma; HBV or HCV: hepatitis B or C virus; miRNAs: microRNAs; CREB: cAMP response element-binding protein; CRE: cAMP response elements.

CircTmeff-1 in the nucleus accumbens regulates the reconsolidation of cocaine-associated memory

Reconsolidation of drug memories is the process of restoring unstable memories after unconditioned (UCS; e.g., drugs) or conditioned stimulus (CS; e.g., drug-paired contexts), and provides promise for prevention of drug relapse. Circular RNAs (circRNAs) have important effects on the transcription and post-transcriptional regulation of gene expression. However, the role of circRNAs in the reconsolidation of drug memories is unclear. Here, we observed that cocaine-induced memory retrieval significantly increased circTmeff-1 level in the nucleus accumbens (NAc) core but not shell. Importantly, the disrupted expression of circTmeff-1 using virus in the NAc core damaged the reconsolidation of cocaine-associated memories. The knockdown of circTmeff-1 in the NAc shell or without UCS retrieval or 9 h after UCS retrieval had no such effects. Mechanistically, using bioinformatic analysis and loss- or gain- of function assays, we revealed that antagomiR-206 reversed the inhibitory effect of circTmeff-1 knockdown on the expression of brain-derived neurotrophic factor (BDNF) during the reconsolidation of cocaine-associated memories. Taken together, these results demonstrate the role of circTmeff-1 in the reconsolidation of cocaine-associated memory and that circTmeff-1 may function as a decoy for miR-206 to regulate the expression of BDNF.

LncRNA SNHG14 Sponges miR-206 to Affect Proliferation, Apoptosis, and Metastasis of Hepatocellular Carcinoma Cells by Regulating SOX9

OBJECTIVE

To explore how lncRNA SNHG14 modulates the biological features of hepatocellular carcinoma (HCC) cells by regulating SOX9 via mediating miR-206.

METHODS

HCC tissues were collected to perform the quantitative reverse transcriptase polymerase chain reaction to determine the expressions of SNHG14, miR-206, and SOX9. HCC cell line SMCC7721 was selected for co-transfection by si-SNHG14/miR-206 inhibitor/si-SOX9, followed by the measurement of cell proliferation using Cell Count Kit-8 (CCK-8) assay and clone formation assay. The migration and invasion were evaluated by wound healing test and Transwell assay. The apoptotic rate was determined by flow cytometry. Levels of the apoptosis-related proteins were measured through Western blotting.

RESULTS

SNHG14 and SOX9 were up-regulated in HCC tumor tissues compared with adjacent normal tissues, with decreased miR-206 expression. Moreover, SNHG14 expression was significantly associated with the TNM stage, lymphatic metastasis, and histological differentiation of HCC patients. Besides, inverse correlations between SNHG14 and miR-206, as well as between miR-206 and SOX9, were noted. The dual luciferase reporter gene assay, RIP, and RNA pull-down experiments also revealed the targeting relationship between SNHG14 and miR-206 or between miR-206 and SOX9. Silencing SNHG14 and SOX9 inhibited the proliferation, invasion, and migration of HCC cells, with increased apoptosis, which was all abolished by silencing miR-206.

CONCLUSION

Inhibition of SNHG14 suppresses SOX9 by up-regulating miR-206, to further inhibit the proliferation, migration, and invasion of HCC cells with the promoted apoptosis, which is a novel target for the treatment of HCC.

Long-chain non-coding RNA UCA1 inhibits renal tubular epithelial cell apoptosis by targeting microRNA-206 in diabetic nephropathy

In this study, the inhibitory effect of long-chain non-coding RNA urothelial carcinoma associated 1 (UCA1) on renal tubular epithelial cell apoptosis by targeting microRNA (miRNA)-206 in diabetic nephropathy (DN) was investigated through DN rat model. The results showed that UCA1 expression was significantly reduced in diabetic renal tubular epithelial tissues and HG-induced HK-2 cells. UCA1 significantly inhibited HG-induced apoptosis and inflammation of renal tubular epithelial cells in HK-2 cells. In addition, UCA1 can directly act as an anti-pro-cytokine by inhibiting the expression of miR-206, and finally inhibit the apoptosis and inflammation of renal tubular epithelial cells. We conclude that UCA1 inhibits renal tubular epithelial cell apoptosis by targeting miRNA-206 in DN and can be used as a potential therapeutic target for DN.

MicroRNA-206 has a bright application prospect in the diagnosis of cases with oral cancer

Previous studies have shown that microRNA‐206 (miR‐206) exhibits anti‐tumour properties in various tumours. Nevertheless, diagnostic significance of miR‐206 in oral cancer is still poorly known. Our research was carried out to explore the performance of miR‐206 in the diagnosis of oral cancer. Quantitative real‐time polymerase chain reaction (qRT‐PCR) method was adopted to measure the level of miR‐206 in serum specimens from oral cancer cases and control individuals. Chi‐square test was performed to analyse the correlation between miR‐206 level and clinicopathological parameters of the cases. Receiver operating characteristic (ROC) curve was constituted to assess diagnostic accuracy of miR‐206 in oral cancer. Serum miR‐206 level in oral cancer patients was significantly lower than that in control individuals (P < .001). miR‐206 expression was obviously related to T classification (P = .033), TNM stage (P = .008) and lymph node metastasis (P = .028). The area under the curve (AUC) of the ROC curve was 0.846 (95% CI = 0.797‐0.896, P < .001) with a specificity of 72.7% and a sensitivity of 81.2%. It revealed that miR‐206 might be a non‐invasive indicator in differentiating oral cancer cases from control individuals. Down‐regulation of miR‐206 is related to the development of oral cancer. Serum miR‐206 might be an effective indicator for early detection of oral cancer.

Differential expression of long non-coding RNA Regulator of reprogramming and its molecular mechanisms in polycystic ovary syndrome

Background

Polycystic ovary syndrome (PCOS) is a common endocrine disease in women of reproductive age. Multiple studies have shown that long non-coding RNAs (lncRNA) and microRNAs (miRNA) play a role in PCOS. This study aimed to explore the role and molecular mechanism of lncRNA -Regulator of reprogramming (lncROR) in PCOS.

Results

Expression level of lncROR in PCOS patients was up-regulated, while level of miR-206 was down-regulated in comparison with control group (P < 0.001). Logistics regression analysis showed that lncROR and miR-206 were independent predictors of PCOS. The ROC curve showed that lncROR had a high diagnostic value for PCOS with an AUC value of 0.893. Pearson correlation coefficient indicated that the expression level of miR-206 was negatively correlated with the level of lncROR. CCK-8 assay and apoptosis assay revealed that downregulation of lncROR up-regulated the expression of miR-206, thereby inhibiting cell proliferation and promoting cell apoptosis. However, silencing the expression of miR-206 reversed the above effects caused by down-regulation of lncROR expression. Luciferase reporter gene assay suggested that there was a target relationship between lncROR and miR-206. VEGF was proved to be the target gene of miR-206.

Conclusions

Highly expressed lncROR indirectly up-regulated the expression of VEGF by down-regulating the expression of miR-206, thereby promoting the proliferation of KGN cells and inhibiting apoptosis, and further promoting the development of PCOS.

MiR-206 regulates the progression of osteoporosis via targeting HDAC4

Background

More and more studies have confirmed that miRNAs play an important role in maintaining bone remodeling and bone metabolism. This study investigated the expression level of miR-206 in the serum of osteoporosis (OP) patients and explored the effect and mechanism of miR-206 on the occurrence and development of osteoporosis.

Methods

120 postmenopausal women were recruited, including 63 cases with OP and 57 women without OP. The levels of miR-206 were determined by qRT-PCR technology. Spearman correlation coefficient was used to evaluate the correlation of miR-206 with bone mineral density (BMD). An ROC curve was used to evaluate the diagnostic value of miR-206 in osteoporosis. The effects of miR-206 on cell proliferation and cell apoptosis of hFOBs were measured by CCK-8 assay and flow cytometry, respectively. Luciferase reporter gene assay was used to confirm the interaction of miR-206 and the 3′UTR of HDAC4.

Results

Serum miR-206 had low expression level in osteoporosis patient group compared with control group. The expression level of serum miR-206 had diagnostic value for osteoporosis, and the serum miR-206 levels were positively correlated with BMD. The down-regulated miR-206 could inhibit cell proliferation and promote cell apoptosis. Luciferase analysis indicated that HDAC4 was the target gene of miR-206.

Conclusions

MiR-206 could be used as a new potential diagnostic biomarker for osteoporosis, and in in vitro cell experiments, miR-206 may regulate osteoblast cell proliferation and apoptosis by targeting HDAC4.

MiR-206 suppresses proliferation and epithelial-mesenchymal transition of renal cell carcinoma by inhibiting CDK6 expression

Increasing evidence indicates that miRNAs are involved in tumorigenesis of human renal cell carcinoma (RCC). However, the role of miR-206 is still unknown. This study aimed to investigate the possible mechanism of miR-206 in progression of RCC. Here, compared with adjacent normal renal tissues and HK-2 cells, miR-206 level was markedly decreased, whereas CDK6 level was obviously increased in RCC tissues and cell lines. MiR-206 was inversely associated with lymph node metastasis and TNM stage, and acted as an independent prognostic factor in RCC. MiR-206 effectively caused apoptosis and cell cycle arrest at G0/G1 phase, and affected the growth of xenograft tumor of nude mice. MiR-206 also inhibited migration and invasion of RCC cells by modulating the expressions of EMT-related genes. Dual-luciferase assay demonstrated CDK6 was a direct target of miR-206. CDK6 silencing aggravated the inhibition effects of miR-206. In conclusion, miR-206 suppresses proliferation and EMT of RCC by inhibiting CDK6 expression. The miR-206/CDK6 axis may provide a novel insight into tumorigenesis of RCC.

miR-206 is required for changes in cell adhesion that drive muscle cell morphogenesis in Xenopus laevis

MicroRNAs (miRNAs) are highly conserved small non-coding RNA molecules that post-transcriptionally regulate gene expression in multicellular organisms. Within the set of muscle-specific miRNAs, miR-206 expression is largely restricted to skeletal muscle and is found exclusively within the bony fish lineage. Although many studies have implicated miR-206 in muscle maintenance and disease, its role in skeletal muscle development remains largely unknown. Here, we examine the role of miR-206 during Xenopus laevis somitogenesis. In Xenopus laevis, miR-206 expression coincides with the onset of somitogenesis. We show that both knockdown and over-expression of miR-206 result in abnormal somite formation affecting muscle cell rotation, attachment, and elongation. In particular, our data suggests that miR-206 regulates changes in cell adhesion that affect the ability of newly formed somites to adhere to the notochord as well as to the intersomitic boundaries. Additionally, we show that β-dystroglycan and F-actin expression levels are significantly reduced, suggesting that knockdown of miR-206 levels affects cellular mechanics necessary for cell shape changes and attachments that are required for proper muscle formation.

MiR-206 inhibits epithelial ovarian cancer cells growth and invasion via blocking c-Met/AKT/mTOR signaling pathway

BACKGROUND

MicroRNAs play important roles in the pathogenesis of various kinds of tumors. However, there are few studies on the expression profile and function of miRNAs in epithelial ovarian cancer. In this study, we performed microRNA array to compare the expression profile of microRNA in ovarian cancer tissues with noncancerous tissues.

METHODS

qRT-PCR was used to further confirm the microRNA expression levels in epithelial ovarian cancer tissues and cell lines. The function of microRNA was analyzed by overexpressing microRNA mimics followed by the analysis of cell cycle, proliferation, and metastasis. The downstream target of miR-206 was found and western blot analysis was performed to measure the activation of the downstream signaling pathway.

RESULTS

In this study, we found the expression of miR-206 was significantly down-regulated in epithelial ovarian cancer tissues and epithelial ovarian cancer cell lines. In epithelial ovarian cancer patients, downregulation of miR-206 was associated with metastasis and poor prognosis. In epithelial ovarian cancer cell lines, miR-206 contributed to the cell cycle regulation, cell apoptosis, and cancer cell metastasis. MiR-206 mimics inhibited cancer cell proliferation and metastasis, and induced cell apoptosis. Moreover, our results demonstrated that miR-206 directly targeted c-Met and repressed the activation of downstream AKT/mTOR signaling pathway.

CONCLUSION

Our results demonstrated that miR-206 was down-regulated in epithelial ovarian cancer tissues and cell lines. MiR-206 inhibits the development of epithelial ovarian cancer cell by directly targeting c-Met and inhibiting the c-Met/AKT/mTOR signaling pathway.

Expression of miR-206 in Human Knee Articular Chondrocytes and Effects of miR-206 on Proliferation and Apoptosis of Articular Chondrocytes

BACKGROUND

Increasing evidence has demonstrated that microRNAs regulate the development of cartilage and osteogenesis. Whether miR-206 participates in the development of human articular cartilage remains largely unknown. This study aimed to investigate the role of miR-206 in human chondrocytes.

METHODS

Expression of miR-206 was initially assessed in human osteoarthritis (OA) tissues and articular chondrocytes through quantitative real-time polymerase chain reaction. The effects of miR-206 on proliferation and apoptosis of human chondrocytes were assessed by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) and Annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) double staining assay. Then, the effects of miR-206 on type II collagen alpha 1 (Col2a1), aggrecan, runt-related transcription factor 2 (RUNX2) and matrix metalloproteinase13 (MMP13) were examined with quantitative real-time polymerase chain reaction and Western blot analysis.

RESULTS

MiR-206 was significantly increased in human OA tissues and chondrocytes. MiR-206 significantly inhibited the proliferation of chondrocytes, but promoted apoptosis. Expression of Col2a1 and aggrecan were dramatically decreased, and the expression of RUNX2 and MMP13 were significantly increased when miR-206 was overexpressed.

CONCLUSIONS

MiR-206 may participate in cartilage degradation in OA. Manipulation of the expression of miR-206 in human chondrocytes may be a novel therapeutic strategy for the treatment of OA.

MiR-206 inhibits Head and neck squamous cell carcinoma cell progression by targeting HDAC6 via PTEN/AKT/mTOR pathway

As a kind of endogenous noncoding small RNA, microRNA (miRNA) plays important roles of regulation to various physiological functions, while its affections on senescence of human Head and neck squamous cell carcinoma (HNSCC) are still unknown. The objective of this study was to investigate the effect of miR-206 in HNSCC tissues, adjacent normal tissues and cell lines, and explore its biological functions in HNSCC. In our study, the level of miR-206 in HNSCC tissues and adjacent normal tissues was detected via real-time qPCR. The effect of miR-206 on cell proliferation was tested by MTT assay, colony formation and cell cycle assays. In order to explore the effect of miR-206 on HNSCC cell migration and invasion, we performed wound healing assays and transwell assays. Luciferase reporter assays were designed to identify the interaction between 3'UTR of HDAC6 and miR-206. The level of signaling pathway-related proteins was determined by western blot. The expression of miR-206 was found to be observably decreased in HNSCC tissues and cell lines through real time-PCR. Restoration of miR-206 weaked cell proliferation, invasion and migration in HNSCC cells and the cell cycle was arrest in S phase. Further explores have shown that miR-206 could inhibit HNSCC cells proliferation by targeting the HDAC6 via PTEN/AKT/mTOR pathway. Taken together, our results demonstrated that miR-206 plays a critical role in HNSCC progression by targeting HDAC6 via PTEN/AKT/mTOR pathway, which might be a potential target for diagnostic and therapeutic in HNSCC.

MiR-34a and miR-206 act as novel prognostic and therapy biomarkers in cervical cancer

Background

Recent evidence indicated that the aberrant expression of microRNA plays a crucial role in the development of cervical cancer. The overall shorter survival was strongly related to the abnormal expression of microRNA-34a (miR-34a) and microRNA-206 (miR-206), which target B cell lymphoma-2(Bcl2) and c-Met. Hepatocyte growth factor (HGF)/c-Met pathway is related to the occurrence, development and prognosis of cervical cancer, and c-Met is significantly overexpressed in cervical squamous cell carcinoma. Bcl2 is also considered to be a promising target for developing novel anticancer treatments.

Methods

In this study, we detect the expression of miR-34a and miR-206 in the cervical cancer tissue through quantificational real-time polymerase chain reaction (qRT-PCR) assay, and the expression of Bcl2 and c-Met from cervical cancer tissue were detected by immunohistochemistry.

Results

The expression of miR-34a and miR-206 were down-regulated in the cervical cancer tissue through qRT-PCR assay. As target genes of miR-34a and miR-206, Bcl2 and c-Met were up-regulated in cervical cancer tissues through qRT-PCR assay and immunohistochemistry. Kaplan–Meier and log-rank analysis revealed that down-regulated expression of miR-34a and miR-206 were strongly related to shorter overall survival. Multivariate Cox proportional hazards model for all variables that were statistically significant in the univariate analysis demonstrated that miR-34a (P = 0.038) and miR-206 (P = 0.008) might be independent prognostic factors for overall survival of patients suffering from cervical cancer.

Conclusions

The up-regulation of Bcl2 and c-Met promotes the cervical cancer’s progress, and the expression of miR-34a and miR-206 significantly correlated with the progression and prognosis in cervical cancer. All of these suggested that miR-34a and miR-206 might be the novel prognostic and therapy tools in cervical cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12935-017-0431-9) contains supplementary material, which is available to authorized users.

WBP2 modulates G1/S transition in ER+ breast cancer cells and is a direct target of miR-206

PURPOSE

The mechanisms underlying the oncogenic properties of WW domain binding protein 2 (WBP2) in breast cancer have not been fully understood. In this study, we explored the role of WBP2 in cell cycle regulation in ER+ breast cancer cells and how it is regulated in the cancer cells.

METHODS

The association between WBP2 expression and prognosis in ER+ breast cancer was assessed by data mining in Breast Cancer Gene-Expression Miner v4.0. Cell cycle was assessed by PI staining and flow cytometry. EdU staining was applied to visualize cells in S phase. The binding between miR-206 and WBP2 were verified by dual luciferase assay. CCK-8 assay and flow cytometric analysis were applied to assess the functional role of WBP2 and miR-206 in the cancer cells.

RESULTS

High WBP2 expression correlates with higher risk of any events (AE) and metastatic relapse (MR) and also indicates shorter AE-free survival and MR-free survival in ER+ breast cancer patients. In both MCF-7 and BT474 cells, WBP can influence the expression of G1/S-related cell cycle proteins, including p21, CDK4, and cyclin D1. In addition, WBP2 overexpression resulted in facilitated G1/S transition, while WBP2 knockdown impaired the transition. The 3'UTR of WBP2 has a conserved miR-206 binding site. Functionally, miR-206 knockdown decreased tamoxifen sensitivity in tamoxifen-sensitive (TamS) MCF-7 cells, while miR-206 overexpression and WBP2 knockdown enhanced the sensitivity in tamoxifen-resistant (TamR) MCF-7 cells.

CONCLUSION

Based on these findings, we infer that the miR-206/WBP2 axis can modulate tamoxifen sensitivity via regulating G1/S progression in ER+ breast cancer.

MicroRNA-206 functions as a tumor suppressor in colorectal cancer by targeting FMNL2

BACKGROUND

Colorectal cancer (CRC) is one of the most common cancers in the world. MicroRNAs play important roles in the progression of CRC. This study aimed to investigate the role of miR-206 and its novel mechanism in the invasion and metastasis of CRC.

METHODOLOGY

Real-time RT-PCR or Western blotting was used to detect the expressions of miR-206, FMNL2 and c-MET in CRC cell lines and tissues. Luciferase reporter assays were conducted to detect the associations between miR-206 and 3'UTRs of FMNL2 and c-MET. A series of loss-of-function and gain-of-function assays were performed to evaluate the effect of miR-206 on the proliferation, invasion and metastasis of CRC cells.

RESULTS

miR-206 was significantly down-regulated in CRC tissues and correlated closely with differentiation, lymphatic metastasis and serosal invasion. miR-206 suppressed CRC cell proliferation by arresting CRC cells in the G1/G0 phase and accelerating apoptosis. miR-206 also inhibited cell invasion and lung metastasis in CRC cells. Mechanically, FMNL2 and c-MET were identified as direct targets of miR-206. And FMNL2 rescued the suppression of miR-206 in the proliferation and invasion of CRC cells.

CONCLUSIONS

This study revealed functional and mechanistic links between miR-206 and oncogene FMNL2 and c-MET in the progression of CRC. miR-206 functioned as a tumor suppressor in the progression of CRC by targeting FMNL2 and c-MET. Restoration of miR-206 expression may represent a promising therapeutic approach for targeting malignant CRC.

Roles of the canonical myomiRs miR-1, -133 and -206 in cell development and disease

MicroRNAs are small non-coding RNAs that participate in different biological processes, providing subtle combinational regulation of cellular pathways, often by regulating components of signalling pathways. Aberrant expression of miRNAs is an important factor in the development and progression of disease. The canonical myomiRs (miR-1, -133 and -206) are central to the development and health of mammalian skeletal and cardiac muscles, but new findings show they have regulatory roles in the development of other mammalian non-muscle tissues, including nerve, brain structures, adipose and some specialised immunological cells. Moreover, the deregulation of myomiR expression is associated with a variety of different cancers, where typically they have tumor suppressor functions, although examples of an oncogenic role illustrate their diverse function in different cell environments. This review examines the involvement of the related myomiRs at the crossroads between cell development/tissue regeneration/tissue inflammation responses, and cancer development.

MyoD transcription factor induces myogenesis by inhibiting Twist-1 through miR-206

Twist-1 is mostly expressed during development and has been previously shown to control myogenesis. Because its regulation in muscle has not been fully exploited, the aim of this project was to identify micro (mi)RNAs in muscle that regulate Twist-1. miR-206, one of the most important muscle-specific miRNAs (myomiRs), was identified as a possible regulator of Twist-1 mRNA. Luciferase assays and transfections in human foetal myoblasts showed that Twist-1 is a direct target of miR-206 and that through this pathway muscle cell differentiation is promoted. We next investigated whether MyoD, a major myogenic transcription factor, regulates Twist-1 because it is known that MyoD induces expression of the miR-206 gene. We found that forced MyoD expression induced miR-206 upregulation and Twist-1 downregulation through binding to the miR-206 promoter, followed by increased muscle cell differentiation. Finally, experiments were performed in muscle cells from subjects with congenital myotonic dystrophy type 1, in which myoblasts fail to differentiate into myotubes. MyoD overexpression inhibited Twist-1 through miR-206 induction, which was followed by an increase in muscle cell differentiation. These results reveal a previously unidentified mechanism of myogenesis that might also play an important role in muscle disease.