[The Role of MicroRNAs in Colorectal Cancer]

Gut microbiota and their derivatives in the progression of colorectal cancer: Mechanisms of action, genome and epigenome contributions

Gut microbiota interacts with host epithelial cells and regulates many physiological functions such as genetics, epigenetics, metabolism of nutrients, and immune functions. Dietary factors may also be involved in the etiology of colorectal cancer (CRC), especially when an unhealthy diet is consumed with excess calorie intake and bad practices like smoking or consuming a great deal of alcohol. Bacteria including Fusobacterium nucleatum, Enterotoxigenic Bacteroides fragilis (ETBF), and Escherichia coli (E. coli) actively participate in the carcinogenesis of CRC. Gastrointestinal tract with chronic inflammation and immunocompromised patients are at high risk for CRC progression. Further, the gut microbiota is also involved in Geno-toxicity by producing toxins like colibactin and cytolethal distending toxin (CDT) which cause damage to double-stranded DNA. Specific microRNAs can act as either tumor suppressors or oncogenes depending on the cellular environment in which they are expressed. The current review mainly highlights the role of gut microbiota in CRC, the mechanisms of several factors in carcinogenesis, and the role of particular microbes in colorectal neoplasia.

Gut microbiota and epigenetics in colorectal cancer: implications for carcinogenesis and therapeutic intervention

Colorectal cancer (CRC) is a leading cause of cancer-related deaths worldwide. The occurrence of CRC is associated with various genetic and epigenetic mutations in intestinal epithelial cells that transform them into adenocarcinomas. There is increasing evidence indicating the gut microbiota plays a crucial role in the regulation of host physiological processes. Alterations in gut microbiota composition are responsible for initiating carcinogenesis through diverse epigenetic modifications, including histone modifications, ncRNAs and DNA methylation. This work was designed to comprehensively review recent findings to provide insight into the associations between the gut microbiota and CRC at an epigenetic level. These scientific insights can be used in the future to develop effective strategies for early detection and treatment of CRC.

MiR-490-5p Restrains Progression of Gastric cancer through DTL Repression

Gastric cancer (GC) accounts for a main cause of cancer-related deaths. This study sought for molecular mechanism of miR-490-5p/DTL axis in affecting GC progression, thus bringing new hope for treatment of GC. Expression data of differentially expressed miRNAs and mRNAs in GC tissue from TCGA database were analyzed. MiR-490-5p and DTL mRNA expression levels in GC were evaluated with qRT-PCR. Cell viability was confirmed with CCK-8 method. Cell cycle distribution and apoptosis were analyzed with flow cytometry. Cell migratory and invasive potential was proved with Transwell assay. The targeted relationship between DTL and miR-490-5p was analyzed with dual-luciferase assay. The results indicated a decreased miR-490-5p level in GC cells. MiR-490-5p upregulation hampered proliferation, migration, invasion and promote cell apoptosis. DTL was the target of and inversely associated with miR-490-5p, and it could remarkably induce the carcinogenesis of GC. MiR-490-5p mediated GC cell progression by DTL repression. In conclusion, miR-490-5p and DTL may be valuable in diagnosis and treatment for GC.

Circular RNA circSP3 promotes hepatocellular carcinoma growth by sponging microRNA-198 and upregulating cyclin-dependent kinase 4

As a new class of endogenous noncoding RNAs, circular RNAs (circRNAs), have been found to influence cell development and function by sponging microRNAs. MicroRNA (miR)-198 is downregulated in various cancers, including hepatocellular carcinoma (HCC). We therefore searched for dysregulated circRNAs that could sponge miR-198 in HCC. By analyzing relevant circRNA databases (circBase, TargetScan and CircInteractome), we found that the miR-198-binding circRNA hsa_circSP3 is upregulated in HCC. CircSP3 expression correlated negatively with miR-198 expression in HCC tissues. Dual luciferase reporter assays indicated that circSP3 bound to miR-198. CircSP3 overexpression in HCC cells induced expression of cyclin-dependent kinase 4, a target gene of miR-198. Silencing circSP3 inhibited HCC cell proliferation and migration by downregulating cyclin-dependent kinase 4, whereas inhibiting miR-198 reversed those effects. In vivo experiments confirmed that circSP3 promoted xenograft tumor growth. These data suggest that circSP3 may be a novel biomarker for HCC.

MiR-194-5p enhances the sensitivity of nonsmall-cell lung cancer to doxorubicin through targeted inhibition of hypoxia-inducible factor-1

Background

Despite chemotherapy being a common treatment, an increase in chemoresistance over time is unavoidable. We therefore investigated the role of miR-194-5p in regulating chordoma cell behavior and examined the downstream effectors of miR-194-5p.

Methods

In this study, NSCLC cell lines A549 and H460 were cultured under hypoxic conditions for 1 week to induce drug resistance to doxorubicin (DOX). The connection between miR-194-5p and HIF-1 was revealed by reverse transcription and real-time polymerase chain reaction (RT-qPCR), western blot, and dual-luciferase assays. We used TUNEL staining and the CCK-8 test to assess the sensitivity of NSCLC cells to DOX.

Results

We found that hypoxia-induced NSCLC cells enhanced resistance to DOX. MiR-194-5p was substantially reduced, and HIF-1 was increased in hypoxia-induced drug-resistant NSCLC cells. Moreover, miR-194-5p successfully induced NSCLC cell apoptosis by directly inhibiting HIF-1, thereby enhancing DOX sensitivity.

Conclusions

MiR-194-5p enhanced the sensitivity of NSCLC cells to DOX by directly inhibiting HIF-1. This work provides insights into underlying treatments for drug-resistant NSCLC.

Sevoflurane inhibits the migration, invasion and induces apoptosis by regulating the expression of WNT1 via miR-637 in colorectal cancer

Colorectal cancer (CRC) is a common malignancy. Sevoflurane has been reported to involve in the progression in several cancers. However, the molecular mechanism of sevoflurane in CRC progression remains unclear. Quantitative real-time PCR and western blot was used to detect the expression of miR-637 and WNT1. Cell migration, invasion and apoptosis were detected by transwell assay, flow cytometry or western blot, respectively. The interaction between WNT1 and miR-637 was confirmed by luciferase reporter assay, RNA immunoprecipitation assay and pull-down assay. We found sevoflurane could inhibit cell migration and invasion but induced apoptosis in CRC. Besides, the miR-637 level was decreased in CRC tissues and cells but could be rescued by sevoflurane. MiR-637 overexpression enhanced the anticancer functions of sevoflurane in CRC cells, while miR-637 inhibition showed opposite effects. WNT1 was confirmed to be a target of miR-637 and was inhibited by sevoflurane or miR-637. Importantly, knockdown of WNT1 reversed the carcinogenic effects mediated by miR-637 inhibitor in CRC cells treated with sevoflurane. Collectively, sevoflurane inhibited cell migration, invasion and induced apoptosis by regulating the miR-637/WNT1 axis in colorectal cancer, indicating a novel insight into the effective clinical implication for the anesthetic in CRC treatment.

Biological Implications and Clinical Potential of Metastasis-Related miRNA in Colorectal Cancer

Colorectal cancer (CRC), ranking as the third commonest cancer, leads to extremely high rates of mortality. Metastasis is the major cause of poor outcome in CRC. When metastasis occurs, 5-year survival rates of patients decrease sharply, and strategies to enhance a patient's lifetime seem limited. MicroRNAs (miRNAs) are evolutionarily conserved small non-coding RNAs that are significantly involved in manipulation of CRC malignant phenotypes, including proliferation, invasion, and metastasis. To date, accumulating studies have revealed the mechanisms and functions of certain miRNAs in CRC metastasis. However, there is no systematic discussion about the biological implications and clinical potential (diagnostic role, prognostic role, and targeted therapy potential) of metastasis-related miRNAs in CRC. This review mainly summarizes the recent advances of miRNA-mediated metastasis in CRC. We also discuss the clinical values of metastasis-related miRNAs as potential biomarkers or therapeutic targets in CRC. Moreover, we envisage the future orientation and challenges in translating these findings into clinical applications.

Identification of MiR-211-5p as a tumor suppressor by targeting ACSL4 in Hepatocellular Carcinoma

BACKGROUND

Liver cancer is among the most common malignancy worldwide. Hepatocellular carcinoma (HCC), the principal histological subtype of liver cancer, is globally the third most common cause of cancer-related mortality. The high rates of recurrence and metastasis contribute to the poor prognosis of HCC patients. In recent years, increasing evidence has shown that microRNAs (miRNAs) are involved in the tumorigenesis, progression, and prognosis of HCC.

METHODS

To screen for key candidate miRNAs in HCC, three microarray datasets were downloaded from Gene Expression Omnibus (GEO). The sole common differentially expressed miRNA (DEmiR) observed in the above three datasets using a Venn diagram was microRNA-211-5p (miR-211-5p). The expression of miR-211-5p from HCC tissues was measured in several HCC cell lines. Additionally, using Kaplan-Meier plots, the potential prognostic value of miR-211-5p in HCC was analyzed. Cell counting kit-8 (CCK-8) and transwell assays examined the ability of miR-211-5p to induce cell proliferation, migration, and invasion in HCC cultures. The interaction of miR-211-5p and Acyl-CoA Synthetase Long Chain Family Member 4 (ACSL4) was assessed both theoretically and using a luciferase reporter assay. Finally, the ability of miR-211-5p to modulate tumorigenesis in HCC in vivo was assessed after establishing a xenograft model.

RESULTS

qRT-PCR demonstrated that the relative expression of miR-211-5p was considerably down-regulated in HCC tissues and cell lines compared with normal tissue. Kaplan-Meier plots indicated that HCC patients with decreased expression of miR-211-5p had poor overall survival. Upregulation of miR-211-5p in vitro consistently suppressed cell proliferation, migration, and invasion. In contrast, enhanced expression of ACSL4 promoted a malignant phenotype in HCC cells. Importantly, we discovered that ACSL4 was a direct downstream target of miR-211-5p in HCC, and that miR-211-5p suppressed the malignant phenotype by inhibition of ACSL4 expression. Furthermore, miR-211-5p overexpression impaired tumorigenesis and growth of HCC in vivo.

CONCLUSIONS

Targeting miR-211-5p and the downstream gene ACSL4 will possibly provide novel insight and represents a promising approach to future therapy of HCC patients.

Colorectal cancer: The epigenetic role of microbiome

Colorectal cancer (CRC) is the third most common cancer in men (746000 cases per year) and the second most common cancer in women globally (614000 cases per year). The incidence rate of CRC in developed countries (737000 cases per year) is higher than that in less developed countries (624000 cases per year). CRC can arise from genetic causes such as chromosomal instability and microsatellite instability. Several etiologic factors underlie CRC including age, diet, and lifestyle. Gut microbiota represent a proven cause of the disease, where they play pivotal roles in modulating and reshaping the host epigenome. Several active microbial metabolites have been found to drive carcinogenesis, invasion, and metastasis via modifying both the methylation landscape along with histone structure in intestinal cells. Gut microbiota, in response to diet, can exert both beneficial and harmful functions in humans, according to the intestinal balance of number and types of these bacteria. Although the intestinal microbial community is diverse among individuals, these microbes cumulatively produce 100-fold more proteins than the human genome itself, which calls for further studies to elaborate on the complicated interaction between these microorganisms and intestinal cells. Therefore, understanding the exact role that gut microbiota play in inducing CRC will help attain reliable strategies to precisely diagnose and treat this fatal disease.

MiR-107 function as a tumor suppressor gene in colorectal cancer by targeting transferrin receptor 1

Background

While microRNAs (miRNAs) are known to play a critical role in the progression of colorectal cancer, the role of miR-107 remains unknown. We evaluated its role and explored the underlying mechanism.

Materials & methods

MTT, wound-healing, transwell migration and transwell invasion assays were performed to evaluate the role of miR-107 in SW629 cell proliferation, migration and invasion. Real time-PCR and dual-luciferase reporter gene, TFR1 overexpression and western blotting assays were used to explore the underlying mechanism.

Results

MiR-107 is downregulated in colorectal cancer tissues and several human colorectal cancer cell lines. Low miR-107 expression often indicates a poor survival rate for colorectal cancer patients. MiR-107 suppresses the proliferation, migration and invasion of SW620 cells by negatively regulating transferrin receptor 1 (TFR1).

Conclusion

MiR-107 suppresses the metastasis of colorectal cancer and could be a potential therapy target in colorectal cancer patients.

Electronic supplementary material

The online version of this article (10.1186/s11658-019-0155-z) contains supplementary material, which is available to authorized users.

O-GlcNAcylation promotes colorectal cancer metastasis via the miR-101-O-GlcNAc/EZH2 regulatory feedback circuit

Advanced colorectal cancer (CRC) is one of the deadliest cancers, and the 5-year survival rate of patients with metastasis is extremely low. The epithelial-mesenchymal transition (EMT) is considered essential for metastatic CRC, but the fundamental molecular basis underlying this effect remains unknown. Here, we identified that O-GlcNAcylation, a unique posttranslational modification (PTM) involved in cancer metabolic reprogramming, increased the metastatic capability of CRC. The levels of O-GlcNAcylation were increased in the metastatic CRC tissues and cell lines, which likely promoted the EMT by enhancing EZH2 protein stability and function. The CRC patients with higher levels of O-GlcNAcylation exhibited greater lymph node metastasis potential and lower overall survival. Bioinformatic analysis and luciferase reporter assays revealed that both O-GlcNAcylation transferase (OGT) and EZH2 are posttranscriptionally inhibited by microRNA-101. In addition, O-GlcNAcylation and H3K27me3 modification in the miR-101 promoter region further inhibited the transcription of miR-101, resulting in the upregulation of OGT and EZH2 in metastatic CRC, thus forming a vicious cycle. In this study, we demonstrated that O-GlcNAcylation, which is negatively regulated by microRNA-101, likely promotes CRC metastasis by enhancing EZH2 protein stability and function. Reducing O-GlcNAcylation may be a potential therapeutic strategy for metastatic CRC.

Novel circular RNA, hsa_circ_0025039 promotes cell growth, invasion and glucose metabolism in malignant melanoma via the miR-198/CDK4 axis

Malignant melanoma, a tumor derived from melanocytes, shows severe drug resistance and prompt metastasis, causing a serious threat to human health. Circular RNAs (circRNAs) are widely expressed in mammals and have been indicated to play important roles in tumorigenesis. In the present study, we analyzed the variability of circRNAs in malignant melanoma by microarray and identified six differentially expressed circRNAs. In particular, we found that hsa_circ_0025039, which is formed by FOXM1 exons, is significantly upregulated in melanoma. In vitro, the knockdown of circ_0025039 inhibited cell proliferation, colony formation ability, invasion and glucose metabolism in melanoma cells. Additionally, we identified miR-198 as a direct target of hsa_circ_0025039. Furthermore, we demonstrated that hsa_circ_0025039 regulates CDK4 expression by sponging miR-198. In vivo study indicated that the silencing of hsa_circ_0025039 inhibits melanoma tumor formation and downregulates miR-198 and CDK4 expression. Taken together, our data showed that circ_0025039 promotes cell growth, invasion and glucose metabolism in malignant melanoma by sponging miR-198 and regulating CDK4.

miRNA-20a upregulates TAK1 and increases proliferation in osteosarcoma cells

AIM

The aim of this study is to explore the function of miR-20a in osteosarcoma.

MATERIALS & METHODS

miR-20a expression was measured by real-time PCR. miR-20a mimics, inhibitor and scramble siRNA were transfected into osteosarcoma cells to observe effects on colony formation and tumor growth. Moreover, relationships of miR-20a with TAK1 were investigated by western blot and luciferase activity.

RESULTS

We found that miR-20a was downregulated in osteosarcoma, and overexpression of miR-20a reduced colony formation and tumor growth. Furthermore, the data revealed that the function of miR-20a was probably exerted via targeting the TAK1 expression. Overexpression of miR-20a sensitizes the osteosarcoma cells to chemotherapeutic drugs.

CONCLUSION

Our data identify the role of miR-20a in osteosarcoma growth, indicating its potential application in chemotherapy.

SIRT1 suppresses colorectal cancer metastasis by transcriptional repression of miR-15b-5p

The class III deacetylase sirtuin 1 (SIRT1), a member of the sirtuin family proteins, plays a key role in many types of cancers including colorectal cancer (CRC). Here we report that SIRT1 suppressed CRC metastasis in vitro and in vivo as a negative regulator for miR-15b-5p transcription. Mechanistically, SIRT1 impaired regulatory effects of activator protein (AP-1) on miR-15b-5p trans-activation through deacetylation of AP-1. Importantly, acyl-CoA oxidase 1 (ACOX1), a key enzyme of the fatty acid oxidation (FAO) pathway, was found as a direct target for miR-15b-5p. SIRT1 expression was positively correlated with ACOX1 expression in CRC cells and in xenografts. Moreover, ACOX1 overexpression attenuated the augmentation of migration and invasion of CRC cells by miR-15b-5p overexpression. In conclusion, our study demonstrated a functional role of the SIRT1/miR-15b-5p/ACOX1 axis in CRC metastasis and suggested a potential target for metastatic CRC therapy.

[Predictive value of miRNA-29a and miRNA-10a-5p for 28-day mortality in patients with sepsis-induced acute kidney injury]

OBJECTIVE

To investigate the value of miR-29a and miR-10a-5p in predicting 28-day mortality in patients with sepsis-induced acute kidney injury.

METHODS

Seventy-four patients with sepsis-induced acute kidney injury (AKI) and 41 patients with sepsis but without AKI (control) were examined for serum levels of miR-29a and miR-10a-5p using RT-PCR. The patients were followed up for 28 days to record their survival. Pearson correlation analysis was used to test the correlations of miR-29a and miR-10a-5p with serum creatinine (Scr), cystatin C (Cys-C), and KIM-1 in patients with AKI. Multivariate logistic regression analysis was used to analyze the correlations of miR-29a, miR-10a-5p, Scr, Cys-C, KIM-1 and other risk factors with the 28-day mortality in patients with sepsis. The predictive value of these indicators for evaluating the prognosis of patients with sepsis was analyzed using ROC curve, and miR-29a combined with miR-10a-5p was assessed for their value in predicting the prognosis of the patients.

RESULT

During the follow-up for 28 days, 21 of the 74 (35.53%) AKI patients died. Compared with the survivors, the patients died within 28 days showed significantly increased serum levels of Scr , Cys-C, KIM-1, miR-29a, and miR-10a-5p (P<0.05). Pearson correlation analysis showed that miR-29a and miR-10a-5p were positively correlated with serum Scr, Cys-C, and KIM-1 levels; multivariate regression analysis identified miR-29a and miR-10a-5p as the independent risk factors for mortality in the septic patients. The ROC curve analysis showed that the area under the curve (AUC) of miR-29a and miR-10a-5p was 0.82 (95%CI: 0.71-0.89) and 0.75 (95%CI: 0.64-0.85), and that of Scr, Cys-C and KIM-1 was 0.72 (95%CI: 0.66-0.86) , 0.71 (95% CI: 0.63-0.84) and 0.81 (95% CI: 0.72-0.81), respectively. The AUC of miR-29a combined with miR-10a-5p was significantly greater than that of miR-29a, miR-10a-5p, Scr, Cys-C and KIM-1 alone (P<0.05).

CONCLUSION

miR-29a and miR-10a-5p have good predictive value in assessing the 28-day mortality of patients with sepsis.