Characterization of human gastric carcinoma-related methylation of 9 miR CpG islands and repression of their expressions in vitro and in vivo

miR-2682-3p antagonizes its host lncRNA-MIR137HG by interacting with the same target FUS to regulate the progression of gastric cancer

Background

The mechanism of long non-coding RNA MIR137HG in human gastric cancer (GC) is currently unknown. In the present study, we aimed to explore the function and mechanism of MIR137HG in gastric cancer.

Methods

The expression of lncRNA-MIR137HG in 69 gastric cancer samples and their paired surgical margin (SM) tissue samples were tested by QRT-PCR. UCSC was used to find the gene location relationship among MIR137HG and its embedded miRNAs. TargetScan was used to predict the targets of miR-2682-3p. Starbase was used to predict the candidate proteins that interacted with MIR137HG. Western blot, co-focus, and RIP assay were used to verify the direct interaction between MIR137HG and FUS (fused in sarcoma/translocated in liposarcoma, FUS/TLS), while dual-luciferase reporter assay was used to confirm the interaction between miR-2682-3p and FUS. Cell migration assays, colony formation, and xenografts assay were used to investigate the function of MIR137HG and miR-2682-3p to tumor growth and metastasis. Western blot assay was used to explore the downstream candidate protein of FUS.

Results

Data showed that MIR137HG expressed significantly higher in GC than in SM. MIR137HG promoted colony formation and migration in vitro and promoted tumor formation and metastasis in vivo. MIR137HG is distributed in both the nucleus and cytoplasm. It was co-located with FUS and could directly interact with FUS, which might interact with other proteins, such as MET(MET-proto-oncogene, receptor tyrosine kinase), RHOC(ras homolog family member), and CTNNB1(catenin beta1). These proteins may involve different signaling pathways to regulate gastric cancer progression. By contrast, the embedded miR-2682-3p could antagonize the series functions of its host lncRNA-MIR137HG by targeting FUS.

Conclusions

lncRNA-MIR137HG promoted growth and metastasis in gastric cancer by interacting with FUS, while miR-2682-3p could inhibit the function of MIR137HG via the same target FUS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09740-9.

MicroRNA-193b impairs muscle growth in mouse models of type 2 diabetes by targeting the PDK1/Akt signalling pathway

AIMS/HYPOTHESIS

Type 2 diabetes is associated with a reduction in skeletal muscle mass; however, how the progression of sarcopenia is induced and regulated remains largely unknown. We aimed to find out whether a specific microRNA (miR) may contribute to skeletal muscle atrophy in type 2 diabetes.

METHODS

Adeno-associated virus (AAV)-mediated skeletal muscle miR-193b overexpression in C57BLKS/J mice, and skeletal muscle miR-193b deficiency in db/db mice were used to explore the function of miR-193b in muscle loss. In C57BL/6 J mice, tibialis anterior-specific deletion of 3-phosphoinositide-dependent protein kinase-1 (PDK1), mediated by in situ AAV injection, was used to confirm whether miR-193b regulates muscle growth through PDK1. Serum miR-193b levels were also analysed in healthy individuals (n = 20) and those with type 2 diabetes (n = 20), and correlations of miR-193b levels with HbA_1c, fasting blood glucose (FBG), body composition, triacylglycerols and C-peptide were assessed.

RESULTS

In this study, we found that serum miR-193b levels increased in individuals with type 2 diabetes and negatively correlated with muscle mass in these participants. Functional studies further showed that AAV-mediated overexpression of miR-193b induced muscle loss and dysfunction in healthy mice. In contrast, suppression of miR-193b attenuated muscle loss and dysfunction in db/db mice. Mechanistic analysis revealed that miR-193b could target Pdk1 expression to inactivate the Akt/mammalian target of rapamycin (mTOR)/p70S6 kinase (S6K) pathway, thereby inhibiting protein synthesis. Therefore, knockdown of PDK1 in healthy mice blocked miR-193b-induced inactivation of the Akt/mTOR/S6K pathway and impairment of muscle growth.

CONCLUSIONS/INTERPRETATION

Our results identified a previously unrecognised role of miR-193b in muscle function and mass that could be a potential therapeutic target for treating sarcopenia.

Methylation-associated miR-193b silencing activates master drivers of aggressive prostate cancer

Epigenetic silencing of miRNA is a primary mechanism of aberrant miRNA expression in cancer, and hypermethylation of miRNA promoters has been reported to contribute to prostate cancer initiation and progression. Recent data have shown that the miR‐193b promoter is hypermethylated in prostate cancer compared with normal tissue, but studies assessing its functional significance have not been performed. We aimed to elucidate the function of miR‐193b and identify its critical targets in prostate cancer. We observed an inverse correlation between miR‐193b level and methylation of its promoter in The Cancer Genome Atlas (TCGA) cohort. Overexpression of miR‐193b in prostate cancer cell lines inhibited invasion and induced apoptosis. We found that a majority of the top 150 genes downregulated when miR‐193b was overexpressed in liposarcoma are overexpressed in metastatic prostate cancer and that 41 miR‐193b target genes overlapped with the 86 genes in the aggressive prostate cancer subtype 1 (PCS1) signature. Overexpression of miR‐193b led to the inhibition of the majority of the 41 genes in prostate cancer cell lines. High expression of the 41 genes was correlated with recurrence of prostate cancer. Knockdown of miR‐193b targets FOXM1 and RRM2 in prostate cancer cells phenocopied overexpression of miR‐193b. Dual treatment with DNA methyltransferase (DNMT) and histone deacetylase (HDAC) inhibitors decreased miR‐193b promoter methylation and restored inhibition of FOXM1 and RRM2. Our data suggest that silencing of miR‐193b through promoter methylation may release the inhibition of PCS1 genes, contributing to prostate cancer progression and suggesting a possible therapeutic strategy for aggressive prostate cancer.

Sulforaphane epigenetically demethylates the CpG sites of the miR-9-3 promoter and reactivates miR-9-3 expression in human lung cancer A549 cells

Increasing evidence suggests that epigenetic aberrations contribute to the development and progression of cancers such as lung cancer. The promoter region of miR-9-3 was recently found to be hypermethylated in lung cancer, resulting in down-regulation of miR-9-3 and poor patient prognosis. Sulforaphane (SFN), a natural compound that is obtained from cruciferous vegetables, has potent anticancer activities. In this study, we aimed to investigate the effect of SFN on restoring the miR-9-3 level in lung cancer A549 cells through epigenetic regulation. DNA methylation of the miR-9-3 promoter was examined using bisulfite genomic sequencing and methylated DNA immunoprecipitation analysis. The expression levels of miR-9-3 and several epigenetic modifying enzymes were measured using quantitative real-time polymerase chain reaction and Western blotting, respectively. The transcriptional activity of the miR-9-3 promoter was evaluated by patch methylation, and histone modifications were analyzed using chromatin immunoprecipitation (ChIP) assays. We found that CpG methylation was reduced in the miR-9-3 promoter and that miR-9-3 expression was increased after 5 days of treatment with SFN. In vitro methylation analysis showed that the methylated recombinant construct exhibited lower luciferase reporter activity than the unmethylated counterpart. ChIP assays revealed that SFN treatment increased H3K4me1 enrichment at the miR-9-3 promoter. Furthermore, SFN treatment attenuated enzymatic DNMT activity and DNMT3a, HDAC1, HDAC3, HDAC6 and CDH1 protein expression. Taken together, these findings indicate that SFN may exert its chemopreventive effects partly through epigenetic demethylation and restoration of miR-9-3.

Aberrant methylation-mediated silencing of microRNAs contributes to HPV-induced anchorage independence

Cervical cancer and a subset of anogenital and head-and-neck carcinomas are caused by high-risk types of the human papillomavirus (hrHPV). During hrHPV-induced malignant transformation keratinocytes become able to grow anchorage independently, a tumorigenic trait at least partly associated with inactivation of tumor suppressor genes. We used hrHPV-containing keratinocytes to investigate the role of DNA methylation-mediated silencing of microRNAs (miRNAs) in the acquisition of anchorage independence.

Anchorage dependent (n=11) and independent passages (n=19) of 4 hrHPV-immortalized keratinocyte cell lines were treated with 2′-deoxy-5-azacytidine (DAC). Genome-wide miRNA expression profiles before and after treatment were compared to identify miRNAs silenced by methylation. Bisulfite sequencing and methylation-specific PCR showed increased methylation of hsa-mir-129-2/-137/-935/-3663/-3665 and -4281 in anchorage independent HPV-transformed keratinocytes and cervical cancer cell lines. Mature miRNAs derived from hsa-mir-129-2/-137/-3663 and -3665 showed functional relevance as they decreased anchorage independence in cervical cancer cell lines. Cervical (pre)cancerous lesions demonstrated increased methylation of hsa-mir-129-2/-935/-3663/-3665 and -4281, underlining the clinical relevance of our findings.

In conclusion, methylation-mediated silencing of tumor suppressive miRNAs contributes to acquisition of an anchorage independent phenotype. This study further substantiates the importance of miRNAs during early stages of carcinogenesis and underlines their potential as both disease markers and therapeutic targets.

miR-193b-Regulated Signaling Networks Serve as Tumor Suppressors in Liposarcoma and Promote Adipogenesis in Adipose-Derived Stem Cells

Well-differentiated and dedifferentiated liposarcomas (WDLS/DDLS) account for approximately 13% of all soft tissue sarcoma in adults and cause substantial morbidity or mortality in the majority of patients. In this study, we evaluated the functions of miRNA (miR-193b) in liposarcoma in vitro and in vivo Deep RNA sequencing on 93 WDLS, 145 DDLS, and 12 normal fat samples demonstrated that miR-193b was significantly underexpressed in DDLS compared with normal fat. Reintroduction of miR-193b induced apoptosis in liposarcoma cells and promoted adipogenesis in human adipose-derived stem cells (ASC). Integrative transcriptomic and proteomic analysis of miR-193b-target networks identified novel direct targets, including CRK-like proto-oncogene (CRKL) and focal adhesion kinase (FAK). miR-193b was found to regulate FAK-SRC-CRKL signaling through CRKL and FAK. miR-193b also stimulated reactive oxygen species signaling by targeting the antioxidant methionine sulfoxide reductase A to modulate liposarcoma cell survival and ASC differentiation state. Expression of miR-193b in liposarcoma cells was downregulated by promoter methylation, resulting at least in part from increased expression of the DNA methyltransferase DNMT1 in WDLS/DDLS. In vivo, miR-193b mimetics and FAK inhibitor (PF-562271) each inhibited liposarcoma xenograft growth. In summary, miR-193b not only functions as a tumor suppressor in liposarcoma but also promotes adipogenesis in ASC. Furthermore, this study reveals key tyrosine kinase and DNA methylation pathways in liposarcoma, some with immediate implications for therapeutic exploration. Cancer Res; 77(21); 5728-40. ©2017 AACR.

Biological implications and clinical value of mir-210 in gastrointestinal cancer

Hypoxia, a common feature of tumor microenvironment, is known to accelerate tumor development and growth by promoting the formation of a neoplastic environment. Recent studies have provided a wealth of evidence that miRNAs are significant members of the adaptive response to low oxygen in tumors. miR-210 is one of the hypoxia-induced miRNAs, which has been reported extensively in cancer researches. However, there is no systematic discussion about the role of miR-210 in gastrointestinal cancer. We conducted a literature research in database including PubMed, Elsevier Science Direct and Medline before 16 September 2016, in order to collect articles of miR-210 in gastrointestinal cancer. Areas covered: In the present review, we mainly discuss the following aspects: hypoxia-induced dysregulation of miR-210, the expression of miR-210 and tumorigenesis, the resultant changes of miR-210 targets and its roles in different types of gastrointestinal cancer progression, the diagnostic, therapeutic and prognostic value of miR-210 in gastrointestinal cancer. Expert commentary: Numerous researches have demonstrated the values of miR-210 in cancer diagnosis, prognosis and targeted therapies, especially in gastrointestinal cancers. However, there are also some existing problems and challenges in translating the new research findings into clinical utility. Further investigations and studies are still urgently required.

Hypoxia-induced miR-210 promoter demethylation enhances proliferation, autophagy and angiogenesis of schwannoma cells

Hypoxia, a dominant feature in cancer occurrence and evolution, exists throughout the progression of most malignant tumors. This study focused on the mechanism of hypoxia-induced miR-210 upregulation, and the miR-210 functions in schwannoma. We detected microvascular density, vascular endothelial growth factor (VEGF) and miR-210 expression levels using schwannoma tissue mciroarray. The results showed that miR-210 expression was significantly associated with VEGF. Moreover, the cytological tests showed that hypoxia induced miR-210 expression, while reduce ephrin-A3 expression. The bisulfate genomic sequencing PCR results showed that miR-210 promoter region was hypermethylated in RT4-D6P2T in normoxia, while demethylated in hypoxia, and the region included the hypoxia-inducible factor-1α (HIF-1α) response element site. Cellular function research showed that hypoxia resulted in RT4-D6P2T apoptosis, higher autophage and invasion. Besides, hypoxia can affect HIF-1α/VEGF-mediated angiogenesis. To learn about the specific functions of miR-210, we found that with miR-210 inhibition, tumor cell apoptosis increased, autophagy and angiogenesis reduced, and the cell cycle was arrested. Hypoxia promoted miR-210 expression through promoter demethylation, then consequently enhanced tumor cell proliferation and autophagy, increasing tumor cell angiogenesis. Thus, miR-210 could be a potential marker for judging tumor malignancy and be taken as an effective target for clinical auxiliary treatment of neurilemmoma.

MicroRNA-203 mimics age-related aortic smooth muscle dysfunction of cytoskeletal pathways

Increased aortic stiffness is a biomarker for subsequent adverse cardiovascular events. We have previously reported that vascular smooth muscle Src-dependent cytoskeletal remodelling, which contributes to aortic plasticity, is impaired with ageing. Here, we use a multi-scale approach to determine the molecular mechanisms behind defective Src-dependent signalling in an aged C57BL/6 male mouse model. Increased aortic stiffness, as measured in vivo by pulse wave velocity, was found to have a comparable time course to that in humans. Bioinformatic analyses predicted several miRs to regulate Src-dependent cytoskeletal remodelling. qRT-PCR was used to determine the relative levels of predicted miRs in aortas and, notably, the expression of miR-203 increased almost twofold in aged aorta. Increased miR-203 expression was associated with a decrease in both mRNA and protein expression of Src, caveolin-1 and paxillin in aged aorta. Probing with phospho-specific antibodies confirmed that overexpression of miR-203 significantly attenuated Src and extracellular signal regulated kinase (ERK) signalling, which we have previously found to regulate vascular smooth muscle stiffness. In addition, transfection of miR-203 into aortic tissue from young mice increased phenylephrine-induced aortic stiffness ex vivo, mimicking the aged phenotype. Upstream of miR-203, we found that DNA methyltransferases (DNMT) 1, 3a, and 3b are also significantly decreased in the aged mouse aorta and that DNMT inhibition significantly increases miR-203 expression. Thus, the age-induced increase in miR-203 may be caused by epigenetic promoter hypomethylation in the aorta. These findings indicate that miR-203 promotes a re-programming of Src/ERK signalling pathways in vascular smooth muscle, impairing the regulation of stiffness in aged aorta.

miR-137 plays tumor suppressor roles in gastric cancer cell lines by targeting KLF12 and MYO1C

Aberrant expression of miR-137 has been reported in many kinds of cancers, but its mechanisms seem to be diversely. In the present study, we compared the expression level of miR-137 in 18 paired gastric cancer (GC) samples and surgical margin (SM) samples by RNA extraction and quantitative real-time PCR (QRT-PCR). Then, we investigated the effects of miR-137 on cell proliferation, cell cycle, and cell migration separately by cell growth counting assay, cell cycle analysis, and transwell assay. Candidate targets of miR-137 were selected by biological information analysis from the intersection of miRDB, Pictar, and TarScan. Finally, mRNA and protein expression level of Krűppel-like factor 12 (KLF12) and Myosin 1C (MYO1C) were tested by QRT-PCR and western blotting assay, followed by the Luciferase reporter assay to investigate the direct interaction between them and miR-137. The results showed that miR-137 was down-regulated in GC samples than in SM samples. The expression level of miR-137 was significantly higher in patients without the vascular embolus than those with vascular embolus. And the overall survival time of patients with high miR-137 expression was longer than those with low miR-137 expression. Over expression of miR-137 could inhibit the cell migration, proliferation, and promote cell cycle arrest in G0/G1 stage in BGC-823 and SGC-7901 cell lines. KLF12 and MYO1C might be the candidate target genes of miR-137 with direct interactions between them and miR-137. In conclusion, miR-137 plays tumor suppressor roles in gastric cancer cell lines by targeting KLF12 and MYO1C.

Detection of ALDH1 activity in rabbit hepatic VX2 tumors and isolation of ALDH1 positive cancer stem cells

Background

Aldehyde dehydrogenase 1 (ALDH1) activity has been implicated in the therapeutic drug resistance of many malignancies and has been widely used as a marker to identify stem-like cells, including in primary liver cancer. Cancer stem cells (CSCs) are thought to play a crucial role in cancer progression and metastasis. In order to clarify the validity of the rabbit VX2 liver cancer model, we questioned if it expresses ALDH1 as a potential marker of CSCs. Hepatocellular carcinoma is a common malignancy worldwide and has poor prognosis. Most of the animal models used to study hepatocellular carcinoma are rodent models which lack clinical relevance. The rabbit VX2 model is a large animal model useful for preclinical and for developing drugs targeting cancer stem cells.

Materials and methods

We used flow cytometry to identify rabbit VX2 liver tumor cells that express ALDH1A1 activity at a high level and confirmed the results with RT-PCR, immunohistochemical and western blot analyses. Further, mRNA and protein expression analysis of tumor samples also express the markers for stemness like klf4, oct3/4, CD44 and nanog as well as the differentiation marker α-fetoprotein.

Results

We used Aldefluor flow cytometry-based assay to identify cells with high ALDH1 activity in the rabbit VX2 liver cancer model. We used the brightest 4.39 % of the total cancer cell population in our study. We performed semi-quantitative as well as real time PCR to characterize the stemness derived from VX2 tumors and tissues from normal rabbit liver. We demonstrated that VX2 tumors have higher expression of cancer stem cell markers such as AlDH1A1 and CD44 in comparison to normal rabbit liver cells. Additionally, real time PCR analysis of the same samples using syber-green demonstrated the significant change (p > 0.05) in the expression of genes. We validated the gene expression of the stemness markers by performing western blot and immunofluorescence. We showed that cancer stem cell markers (AlDH1A1, CD44) and the differentiation marker α-fetoprotein were upregulated in VX2 tumor cells. The same extent of upregulation was observed in stemness markers (klf4, oct3/4 and nanog) in VX2 tumors in comparison to normal rabbit liver.

Conclusion

The overall results of this study indicate that ALDH1 is a valid CSC marker for VX2 cancer. This finding suggests that the rabbit VX2 liver cancer model is useful in studying drug resistance in hepatocellular carcinoma and may be useful for basic and preclinical studies of other types of human cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-0785-0) contains supplementary material, which is available to authorized users.

Dysregulation of non-coding RNAs in gastric cancer

Gastric cancer (GC) is one of the most common cancers in the world and a significant threat to the health of patients, especially those from China and Japan. The prognosis for patients with late stage GC receiving the standard of care treatment, including surgery, chemotherapy and radiotherapy, remains poor. Developing novel treatment strategies, identifying new molecules for targeted therapy, and devising screening techniques to detect this cancer in its early stages are needed for GC patients. The discovery of non-coding RNAs (ncRNAs), primarily microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), helped to elucidate the mechanisms of tumorigenesis, diagnosis and treatment of GC. Recently, significant research has been conducted on non-coding RNAs and how the regulatory dysfunction of these RNAs impacts the tumorigenesis of GC. In this study, we review papers published in the last five years concerning the dysregulation of non-coding RNAs, especially miRNAs and lncRNAs, in GC. We summarize instances of aberrant expression of the ncRNAs in GC and their effect on survival-related events, including cell cycle regulation, AKT signaling, apoptosis and drug resistance. Additionally, we evaluate how ncRNA dysregulation affects the metastatic process, including the epithelial-mesenchymal transition, stem cells, transcription factor activity, and oncogene and tumor suppressor expression. Lastly, we determine how ncRNAs affect angiogenesis in the microenvironment of GC. We further discuss the use of ncRNAs as potential biomarkers for use in clinical screening, early diagnosis and prognosis of GC. At present, no ideal ncRNAs have been identified as targets for the treatment of GC.

Investigation of miR9-1, miR9-2 and miR9-3 Methylation in Hodgkin Lymphoma

BACKGROUND

miR9 is an important tumor suppressor microRNA regulated by DNA methylation in various types of cancers.

METHODS

We analyzed the methylation status of the 3 members of the miR9 family in 58 cases of Hodgkin lymphoma (HL) in comparison to 15 reactive lymph nodes. We also assessed the relationships between miR9 methylation and Epstein-Barr virus (EBV) infection and several clinicopathological parameters.

RESULTS

We found that 84.5% of HL cases had a methylation in at least 1 of the 3 loci of miR9, whereas none of the nontumoral samples was methylated. The highest rate of methylation was found in miR9-2 (5q14.3) in 74.1% of the HL cases, followed by miR9-3 (15q26.1) in 56.9% and miR9-1 (1q22) in only 8.6% (p < 0.001). The promoter methylation of miR9-3 was more frequent in patients older than 15 years than in children (p = 0.02) and among women rather than men (p = 0.02). However, no significant correlation was found between miR9 methylation and EBV infection.

CONCLUSION

These results indicate that miR9 methylation, especially miR9-2, is a frequent event in HL and may be involved in HL pathogenesis, irrespective of EBV infection.

Epigenetic silencing of miR-137 is a frequent event in gastric carcinogenesis

MicroRNAs (miRNA) are involved in posttranscriptional regulation of gene expression and are dysregulated during carcinogenesis. CpG island methylation of miR-137 is a common event in different cancers; however, the role of miR-137 in gastric cancer (GC) remains largely unexplored. In this study we aimed to characterize the epigenetic alterations of miR-137 in gastric carcinogenesis. We analyzed total 295 tissues including paired primary gastric cancer (T-GC) with corresponding adjacent gastric mucosa (N-GC), paired primary colorectal cancer (CRC) tissues with corresponding non-tumorous mucosa, gastric tissues from controls (N), and patients with chronic/atrophic gastritis (CG) with and without Helicobacter pylori infection. Bisulfite pyrosequencing and TaqMan RT-PCR were used to analyze miR-137 methylation and expression, respectively. Survival differences were evaluated using Kaplan-Meier analyses. miR-137 CpG island methylation was more frequent in tumorous compared to non-tumorous conditions and higher in CRC than in GC. In comparison to N-GC, miR 137 methylation level was lower in N and CG tissues, which correlates with Correas cascade. MiR-137 methylation inversely correlates with global LINE-1 methylation and miR-137 expression. miR-137 methylation was higher in intestinal type GC compared to diffuse one, and higher in antrum compared to cardia and corpus, however, miR-137 methylation was associated with worse prognosis in diffuse, but not in intestinal type of GC. The expression in colon was significantly higher compared to any gastric tissues suggesting functional difference. In summary, miR-137 methylation is a frequent event in gastrointestinal cancers which occurs early in stepwise manner during gastric carcinogenesis and inversely correlates with global methylation. © 2015 Wiley Periodicals, Inc.

MIR210 as a potential molecular target to block invasion and metastasis of gastric cancer

The epithelial-mesenchymal transition (EMT) is a process driving invasion, recurrence, and metastasis of gastric cancer, and EMT is triggered by specific physiological factors that arise during tumorigenesis, such as hypoxia. Identifying the molecular mechanisms underlying EMT will potentially yield insight into the pathways fueling cancer recurrence and metastasis and thus, lead to novel molecular targets that will improve treatment of the disease. The microRNA210 (MIR210) is such a candidate molecule mediating EMT in gastric cancer based on a number of observations. First, MIR210 is often highly overexpressed in gastric cancer. Second, MIR210 is a hypoxia-specific miRNA, and its expression is significantly increased in hypoxic environments where EMT develops. Third, MIR210 is regulated by hypoxia inducible factor 1α (HIF-1α), a key transcription factor mediating important tumor associated processes such as EMT and angiogenesis in response to hypoxia during tumorigenesis. Finally, MIR210 has been intriguingly associated with Helicobacterpylori infection, which typically develops in an anaerobic environment and is known to have a causal role in the development of gastric cancer. Although studies have shown that MIR210 is often highly expressed in gastric cancer and associated with specific pathological conditions, functional experiments have not yet been performed to determine the role of MIR210 and downstream mediators in the development and progression of gastric cancer. Here, MIR210 is proposed as a viable molecular target in the treatment of gastric cancer, specifically for the inhibition of invasion and metastasis.

MicroRNA library-based functional screening identified miR-137 as a suppresser of gastric cancer cell proliferation

PURPOSES

Uncontrolled proliferation is a key characteristic of gastric carcinogenesis and the precise mechanisms underlying the altered proliferation behaviors of GC cells have not been clearly elucidated. miRNAs has been suggested to play a crucial role in the pathogenesis and development of various cancers. In the present study, we employed an impedance-based real-time cell electronic sensing (RT-CES) system to detect the effects of ectopically expressed miRNAs on GC cell proliferation.

METHODS

miRNA mimics were transfected into gastric cancer cell line SGC7901 and the effect of individual miRNA on the proliferation rate of the cells was measured by the RT-CES system. The screening results were validated with qRT-PCR and miR-137 was selected for further research. The effects of ectopically expressed miR-137 on GC cell growth and cell cycle progress were measured using MTT assay and flow cytometry. The target gene of miR-137 was predicted using different bioinformatics tools and the direct interaction between miR-137 and the 3'-UTR was confirmed with a luciferase reporter assay. The in vivo effect of miR-137 on GC cell proliferation was examined with a tumor-bearing nude mouse model. The correlation between miR-137 expression and patients' prognosis was explored in a cohort of 38 patients. Prognosis was explored in a cohort of 38 patients.

RESULTS

Ectopic expression of miR-137 was sufficient to inhibit GC cell proliferation both in vitro and in vivo. Bioinformatics prediction and luciferase reporter assay revealed CDK6 as a target gene through which miR-137 exerted an inhibitory function. Moreover, miR-137 expression positively correlated with better prognosis.

CONCLUSION

Our data indicated an important regulatory role of miR-137 in GC cell proliferation and that it may be explored as a prognostic marker for GC.

Epigenetic silencing of miRNA-9 is correlated with promoter-proximal CpG island hypermethylation in gastric cancer in vitro and in vivo

Silencing of protein-coding tumor suppressor genes (TSGs) by CpG island hypermethylation is a common occurrence in gastric cancer (GC). Here, we examine if tumor suppressor microRNAs (miRNAs) are silenced in a similar manner. Real-time quantitative PCR (RTQ-PCR) was employed to investigate the expression level of four candidate miRNAs in GC tissues (n=30) and cell lines. Basing on RTQ-PCR results and bioinformatics approach, miR-9 was chosen for further study on epigenetic regulation. Bisulfite genomic sequencing PCR (BSP) was performed to assess the methylation status of miR-9 in GC tissues. In both GC cell lines and animal models, demethylation was performed either by treatment with 5-aza-2'-deoxycytidine (5-AZA-CdR) or by siRNA targeting DNMT1. We also analyzed the relationship between miRNAs and several clinicopathological features. Candidate miRNAs (miR-9, miR-433, miR-19b, and miR-370) were found strongly downregulated in GC tissues and cell lines. Their expression was increased following 5-AZA-CdR treatment. CpG island methylation of miR-9 was significantly higher in GC tissues compared to normal controls. After two demethylation treatments, miR-9 methylation degree was significantly decreased and miR-9 expression was ob-viously restored in GC cells and animal models. Deregulation of miR-9 was positively correlated with tumor lesion size. Three other miRNAs, miR-19b, miR-433, and miR-370 were assοciated with lymph node metastasis, decreased curvature, and poorly differentiated carcinoma. miR-19b and miR-433 were positively correlated with male gender. Of four candidate miRNAs downregulated in GC, miR-9 is epigenetically regulated by DNA methylation both in vitro and in vivo.

Expression of RNF180 and RECK in gastric carcinoma

AIM: To detect the expression of ring finger protein 180 (RNF180) and reversion-inducing-cysteine-rich protein with Kazal motifs (RECK) in gastric carcinoma.

METHODS: Western blot and reverse transcription-polymerase chain reaction (RT-PCR) were used to detect the expression of RECK and RNF180 in gastric cancer, pericarcinomatous tissue and normal gastric mucosal tissue.

RESULTS: The positive rates of RNF180 expression in gastric cancer and pericarcinomatous tissue were significantly lower than that in normal gastric mucosal tissue (68.7%, 28.4% vs 6.1%, P < 0.05). RECK expression was significantly lower in gastric carcinoma and pericarcinomatous tissue than in normal gastric mucosal tissue (71.4%, 31.6% vs 5.3%, P < 0.05).

CONCLUSION: RNF180 and RECK expression in gastric cancer is significantly reduced, suggesting that they may play an important role in the development of gastric cancer.

miR-137 effects on gastric carcinogenesis are mediated by targeting Cox-2-activated PI3K/AKT signaling pathway

The discovery of microRNAs (miRNAs) provided a new avenue for early diagnosis and treatment of GC. MiR-137 has been reported to be under-expressed and involved in various cell processes. However, the role of miR-137 in GC is less known. In this study, we show that miR-137 is under-expressed in GC and functions as a tumor suppressor through targeting Cyclooxygenase-2 (Cox-2), which subsequently suppresses the activation of PI3K/AKT signaling pathway both in vitro and in vivo. Moreover, restored Cox-2 expression partially abolished the tumor suppressive effects of miR-137 in GC cells, suggesting miR-137 may suppress GC carcinogenesis by targeting Cox-2.

DNA methylation, microRNAs, and their crosstalk as potential biomarkers in hepatocellular carcinoma

Epigenetic alterations have been identified as a major characteristic in human cancers. Advances in the field of epigenetics have contributed significantly in refining our knowledge of molecular mechanisms underlying malignant transformation. DNA methylation and microRNA expression are epigenetic mechanisms that are widely altered in human cancers including hepatocellular carcinoma (HCC), the third leading cause of cancer related mortality worldwide. Both DNA methylation and microRNA expression patterns are regulated in developmental stage specific-, cell type specific- and tissue-specific manner. The aberrations are inferred in the maintenance of cancer stem cells and in clonal cell evolution during carcinogenesis. The availability of genome-wide technologies for DNA methylation and microRNA profiling has revolutionized the field of epigenetics and led to the discovery of a number of epigenetically silenced microRNAs in cancerous cells and primary tissues. Dysregulation of these microRNAs affects several key signalling pathways in hepatocarcinogenesis suggesting that modulation of DNA methylation and/or microRNA expression can serve as new therapeutic targets for HCC. Accumulative evidence shows that aberrant DNA methylation of certain microRNA genes is an event specifically found in HCC which correlates with unfavorable outcomes. Therefore, it can potentially serve as a biomarker for detection as well as for prognosis, monitoring and predicting therapeutic responses in HCC.

Survival of motor neuron protein downregulates miR-9 expression in patients with spinal muscular atrophy

Spinal muscular atrophy (SMA) is a lethal hereditary disease caused by homozygous absence of the survival of the motor neuron (SMN) 1 gene (SMN1), and it is the leading genetic cause of infant mortality. The severity of SMA is directly correlated with SMN protein levels in affected patients; however, the cellular regulatory mechanisms for SMN protein expression are not completely understood. In this study, we investigated the regulatory effects between SMN expression and miR-9a, a downstream noncoding small RNA. Using an inducible SMN short hairpin RNA interference (shRNAi) system in NSC 34 and human skin fibroblast cells, cellular miR-9 levels and SMN protein repression were time-dependently upregulated. Conversely, cellular miR-9 levels decreased when HeLa cells were transfected with SMN protein fused with green fluorescent protein. In SMA-like mice spinal cords and human primary skin fibroblasts isolated from patients with different degrees of SMA, human SMN exhibited a disease severity-dependent decrease, whereas cellular miR-9 levels increased. These results clearly suggested that cellular SMN proteins regulated miR-9 expression and that miR-9 expression was related to SMA severity. Thus, miR-9 may be a marker for SMA prognosis.

The emerging role of miR-375 in cancer

MicroRNAs (miRNAs) are evolutionarily conserved, small noncoding RNAs that are believed to play fundamental roles in various biological processes through regulation of gene expression at the level of posttranscription. MiR-375 was first identified as a pancreatic islet-specific miRNA regulating insulin secretion. However, further study revealed that miR-375 is a multifunctional miRNA participating in pancreatic islet development, glucose homeostasis, mucosal immunity, lung surfactant secretion and more importantly, tumorigenesis. Recently, miR-375 has been found significantly downregulated in multiple types of cancer, and suppresses core hallmarks of cancer by targeting several important oncogenes like AEG-1, YAP1, IGF1R and PDK1. The alteration of miR-375 in cancer is caused by a variety of mechanisms, including the dysregulation of transcription factors, aberrant promoter methylation and so on. Reduced expression of miR-375 in tissue or circulation may indicate the presence of neoplasia as well as a poor prognosis of many malignant cancers. Moreover, miR-375 stands for a promising direction for developing targeted therapies due to its capacity to inhibit tumor cell growth in vitro and in vivo. Here, we summarize the present understanding of the tumor suppressive role of miR-375 in cancer progression; the mechanisms underlying the dysregulation of miR-375; the potential use of miR-375 in prognosis and diagnosis and the therapeutic prospects of miR-375 in cancer.

miR-9 functions as a tumor suppressor in ovarian serous carcinoma by targeting TLN1

microRNAs (miRNAs) are important regulators of gene expression during tumorigenesis. The downregulation of microRNA-9 (miR-9) has been reported in ovarian serous carcinoma (OSC), indicating a role for miR-9 in this type of cancer. In this study, we investigated the biological significance of miR-9 in OSC in vitro. Using 3 OSC cell lines, SKOV3, CAOV3 and OVCAR3, which underexpresss miR-9, we demonstrate that the exogenous miR-9 transfection inhibits OSC cell proliferation, migration and invasion. In addition, we demonstrate that the focal adhesion protein, talin 1 (TLN1), whose expression has been associated with OSC development and progression to metastasis, is a direct target of miR-9. TLN1 knockdown mimicked the effects of miR-9 overexpression. Moreover, the activation of the TLN1-modulated FAK/AKT pathway was inhibited by the increased miR-9 levels. These results suggest that miR-9 plays a role as a tumor suppressor in OSC by suppressing TLN1 expression.

Hypoxia-inducible factor 1-α induces miR-210 in normoxic differentiating myoblasts

MicroRNA-210 (miR-210) induction is a virtually constant feature of the hypoxic response in both normal and transformed cells, regulating several key aspects of cardiovascular diseases and cancer. We found that miR-210 was induced in normoxic myoblasts upon myogenic differentiation both in vitro and in vivo. miR-210 transcription was activated in an hypoxia-inducible factor 1-α (Hif1a)-dependent manner, and chromatin immunoprecipitation experiments show that Hif1a bound to the miR-210 promoter only in differentiated myotubes. Accordingly, luciferase reporter assays demonstrated the functional relevance of the Hif1a binding site for miR-210 promoter activation in differentiating myoblasts. To investigate the functional relevance of increased miR-210 levels in differentiated myofibers, we blocked miR-210 with complementary locked nucleic acid oligonucleotides (anti-miR-210). We found that C2C12 myoblast cell line differentiation was largely unaffected by anti-miR-210. Likewise, miR-210 inhibition did not affect skeletal muscle regeneration following cardiotoxin damage. However, we found that miR-210 blockade greatly increased myotube sensitivity to oxidative stress and mitochondrial dysfunction. In conclusion, miR-210 is induced in normoxic myofibers, playing a cytoprotective role.

MicroRNAs in cancers and neurodegenerative disorders

MicroRNAs (miRNAs) are small non-coding RNAs which function as endogenous silencers of various target genes. miRNAs are expressed in a tissue-specific manner and playing important roles in cell proliferation, apoptosis, and differentiation during mammalian development. Links between miRNAs and the initiation and progression of human diseases including cancer are becoming increasingly apparent. Recent studies have revealed that some miRNAs such as miR-9, miR-29 family, and miR-34 family are differentially expressed in Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease. These miRNAs are also reported to act as tumor suppressors during human carcinogenesis. In this review, we discuss about miRNAs which are important in the molecular pathogenesis of both cancer and neurodegeneration. Cancer and neurodegenerative disorder may be influenced by common miRNA pathways that regulate differentiation, proliferation, and death of cells.