Maintenance of gut barrier integrity after injury: Trust your gut microRNAs

The gastrointestinal (GI) tract is a highly dynamic structure essential for digestion, nutrient absorption, and providing an interface to prevent gut bacterial translocation. In order to maintain the barrier function, the gut utilizes many defense mechanisms including proliferation, apoptosis, and apical junctional complexes. Disruption of any of these parameters due to injury or disease could negatively impact the intestinal barrier function and homeostasis resulting in increased intestine inflammation, permeability, bacterial dysbiosis, and tissue damage. MicroRNAs are small noncoding RNA sequences that are master regulators of normal cellular homeostasis. These regulatory molecules affect cellular signaling pathways and potentially serve as candidates for providing a mechanism of impaired gut barrier integrity following GI-related pathologic conditions, ethanol exposure, or trauma such as burn injury. MicroRNAs influence cellular apoptosis, proliferation, apical junction complex expression, inflammation, and the microbiome. Due to their widespread functional affiliations, altered expression of microRNAs are associated with many pathologic conditions. This review explores the role of microRNAs in regulation of intestinal barrier integrity. The studies reviewed demonstrate that microRNAs largely impact intestine barrier function and provide insight behind the observed adverse effects following ethanol and burn injury. Furthermore, these studies suggest that microRNAs are excellent candidates for therapeutic intervention or for biomarkers to manage gut barrier integrity following trauma such as burn injury and other GI-related pathologic conditions.

The association of miR-27a rs895819 polymorphism with colorectal cancer risk in Chinese population

Background

Besides environment and living habits, such as a sedentary lifestyle, smoking and drinking, genetic variation also plays an important role in the development of colorectal cancer (CRC). This study was aimed to investigate the role of miR‑27a rs895819 polymorphism on CRC risk in Chinese population.

Methods

In a case‐control study including 208 CRC and 312 age‐ and gender‐matched healthy control subjects, the rs895819 polymorphism was genotyped using the TaqMan allelic discrimination assay. Furthermore, a pooled analysis based on eligible studies was performed by using the STATA software.

Results

Logistic regression analysis showed that the rs895819 polymorphism was not associated with CRC risk. However, a pooled analysis based on five studies from Chinese population showed a statistically significant association between the rs895819 polymorphism and CRC risk (GG vs AA: OR = 1.56, 95% CI = 1.27‐1.92, Pz < .01; (AG + GG) vs AA: OR = 1.14, 95% CI = 1.01‐1.30, Pz = .04; GG vs (AG + AA): OR = 1.54, 95% CI = 1.27‐1.88, Pz < .01; G vs A: OR = 1.20, 95% CI = 1.09‐1.33, Pz < .01).

Conclusion

Our study suggests that miR‑27a rs895819 polymorphism plays an important role in CRC risk in Chinese population and may serve as a valuable biomarker for predicting an individual's susceptibility to CRC.

MiR-27a: A Novel Biomarker and Potential Therapeutic Target in Tumors

MicroRNAs (miRNAs) are endogenous, time sequencing, conserved and small non-coding RNA molecules (19-25 bp long) that regulate gene expression at the post-transcriptional level by binding to the partial sequence homology of the 3'-untranslated region of target messenger (m)RNA. The miRNA-27 family consists of miR-27a and miR-27b, which are transcribed from different chromosomes and different in nucleotide at the 3' end. It has been reported that miR-27a was located on chromosome 19 and played a vital role in tumor development. Increasing evidences support a vital role for miR-27a in modulating polymorphisms, tumorigenesis, proliferation, apoptosis, invasion, migration and angiogenesis. Apart from it, miR-27a could affect drug sensitivity, treatment of cancer and patients prognosis. The miR-27a could be an oncogene or a tumor suppressor in several types of cancer, including colon cancer, pancreatic cancer, breast cancer, bladder cancer and hepatocellular carcinoma. In this review, we discuss the role of miR-27a in tumor biology and clinical significance in detail and offer novel insights into molecular targeting therapy for human cancers.

Obesity-associated miR-27a upregulation promotes hepatocellular carcinoma metastasis through suppressing SFRP1

Background

Obesity was a recognized risk factor for the development and progression of hepatocellular carcinoma (HCC). However, the effects and mechanisms by which obesity promotes HCC metastasis remain poorly understood.

Materials and methods

We cultured adipocyte induced by preadipocyte 3T3-L1 in vitro and established HCC metastasis model in obesity mouse in vivo to mimic the tumor microenvironment in obese status. The mechanisms underlying obesity-associated miR-27a upregulation promoting HCC metastasis were investigated.

Results

In this study, we showed that miR-27a was upregulated in adipocytes, obese mouse model and clinical samples, and the increased miR-27a level promoted migration and invasion in HCC cells, increased the number of metastasis nodes in obese mouse model, and was associated with poor clinical outcomes. Overexpressed secreted frizzled-related protein 1 in HCC cells and tissues significantly alleviated the upregulation of β-catenin and matrix metalloproteinase-7 induced by high level of miR-27a. Meanwhile, the E-cadherin expression decreased and Vimentin expression increased, linking with high level of β-catenin in high-fat group.

Conclusion

Taken together, our results have elucidated the critical role of extracellular miR-27a as a pro-metastatic factor in HCC and revealed that obesity-associated miR-27a upregulation promoted HCC metastasis through activated Wnt/β-catenin signaling by suppressing secreted frizzled-related protein 1. Our findings shed light on the novel mechanism underlying HCC metastasis and provided miR-27a as a promising target for obese liver cancer therapy.

Comparative miRNA Expression Profile Analysis of Squamous Cell Carcinoma and Peritumoral Mucosa from the Meso- and Hypopharynx

BACKGROUND/AIM

The role of microRNAs (miRNA) in carcinogenesis is related to their genome-regulatory function. The aim of the present study was to identify and compare miRNA expression signatures of meso- and hypopharynx squamous cell cancers in consideration of the cancer field hypothesis.

PATIENTS AND METHODS

Thirteen snap-frozen biopsy series of tumors and peritumoral tissues from the meso- and hypopharynx were analyzed regarding their miRNA expression with quantitative real-time polymerase chain reaction (qRT-PCR).

RESULTS

Significant miRNA expression changes of miR-21, -27a, -34a, -143 and -146a were found in peritumoral tissues that were dependent from the tumor location and the distance from the primary tumor site.

CONCLUSION

miRNA expression analysis was found to be appropriate for molecular segregation of tumor location and peritumoral tissue segments, and appears to be a promising marker for cancer field characterization.

MicroRNA-27a functions as an oncogene in human osteosarcoma by targeting CCNG1

Osteosarcoma is the most common type of malignant tumor arising from bone in children and adolescents. Accumulating evidences have shown the aberrant expression of numerous miRNAs is associated with the development and metastasis of osteosarcoma. The present study was conducted to investigate miR-27a expression in osteosarcoma tissues and cells. In the present study, quantitative RT-qPCR was used to measure the expression levels of miRNA and mRNA in osteosarcoma tissues and cells. Transwell assays were used to detect the effects of miR-27a on the invasive and migratory potential of cells. Luciferase reporter and western blot analysis were conducted to confirm cyclin G1 (CCNG1) as the target gene of miR-27a. The results showed that miR-27a was significantly upregulated in human osteosarcoma tissues and cell lines. The western blot analysis revealed that the overexpression of miR-27a suppressed CCNG1 protein expression. Luciferase reporter assays confirmed that CCNG1 is a direct target of miR-27a in osteosarcoma cells. The results suggest that miR-27a downregulates CCNG1 expression in osteosarcoma and acts as an oncogene directly targeting CCNG1. Thus, the miR-27a/CCNGI axis is a potential therapeutic target for human osteosarcoma.

miR-27a-3p targeting RXRα promotes colorectal cancer progression by activating Wnt/β-catenin pathway

This study aimed to elucidate how miR-27a-3p modulates the Wnt/β-catenin signaling pathway to promote colorectal cancer (CRC) progression. Our results showed that the expression of miR-27a-3p was up-regulated in CRC and closely associated with histological differentiation, clinical stage, distant metastasis and CRC patients' survival. miR-27a-3p mimic suppressed apoptosis and promoted proliferation, migration, invasion of CRC cells in vitro and in vivo. Whereas miR-27a-3p inhibitor promoted apoptosis and suppressed proliferation, migration, invasion of CRC cells in vitro and in vivo. Furthermore, RXRα was the target gene of miR-27a-3p in CRC. miR-27a-3p expression negatively correlated with RXRα expression in CRC tissues. The underlining mechanism study showed that miR-27a-3p/RXRα/Wnt/β-catenin signaling pathway is involved in CRC progression. In conclusion, our findings first demonstrate that miR-27a-3p is a prognostic and/or potential therapeutic biomarker for CRC patients and RXRα as miR-27a-3p targeting gene plays an important role in activation of the Wnt/β-catenin pathway during CRC progression.

MicroRNAs: Potential candidates for diagnosis and treatment of colorectal cancer

Colorectal cancer (CRC) is known as the third common cancer worldwide and an important public health problem in different populations. Several genetics and environmental risk factors are involved in the development and progression of CRC including chromosomal abnormalities, epigenetic alterations, and unhealthy lifestyle. Identification of risk factors and biomarkers could lead to a better understanding of molecular pathways involved in CRC pathogenesis. MicroRNAs (miRNAs) are important regulatory molecules which could affect a variety of cellular and molecular targets in CRC. A large number of studies have indicated deregulations of some known tissue-specific miRNAs, for example, miR-21, miR-9, miR-155, miR-17, miR-19, let-7, and miR-24 as well as circulating miRNAs, for example, miR-181b, miR-21, miR-183, let-7g, miR-17, and miR-126, in patients with CRC. In the current review, we focus on the findings of preclinical and clinical studies performed on tissue-specific and circulating miRNAs as diagnostic biomarkers and therapeutic targets for the detection of patients at various stages of CRC.

MiR-150-5p suppresses colorectal cancer cell migration and invasion through targeting MUC4

Growing evidence suggests that miR-150-5p has an important role in regulating genesis of various types of cancer. However, the roles and the underlying mechanisms of miR-150-5p in development of colorectal cancer (CRC) remain largely unknown. Transwell chambers were used to analyze effects on cell migration and invasion by miR-150-5p. Quantitative real-time PCR (qRT-PCR), Western blotting and dual-luciferase 3' UTR reporter assay were carried out to identify the target genes of miR-150-5p. In our research, miR-150-5p suppressed CRC cell migration and invasion, and MUC4 was identified as a direct target gene. Its effects were partly blocked by re-expression of MUC4. In conclusiomn, miR-150-5p may suppress CRC metastasis through directly targeting MUC4, highlighting its potential as a novel agent for the treatment of CRC metastasis.

Post-transcriptional regulation of the tumor suppressor p53 by a novel miR-27a, with implications during hypoxia and tumorigenesis

The tumor suppressor protein p53 is intricately regulated by various signaling molecules, including non-coding small RNAs, called microRNAs (miRNAs). The in silico analysis and the inverse expression status in various cell lines raised the possibility of miR-27a being a new regulator of p53. Using luciferase reporter assay and various mutational and functional analysis, we identified two putative binding sites of miR-27a on the 3'-UTR of p53. The overexpression of miR-27a in the human colorectal cancer cell line HCT-116^+/+ resulted in the decreased expression of the endogenous p53 protein levels. During hypoxia of the HCT-116^+/+ cells, p53 showed increased accumulation after 3 h, and the levels were significantly up-regulated until 24 h of hypoxia. The p53 expression dynamics during hypoxia of the HCT-116^+/+ cells were found to be inversely regulated by miR-27a expression. Moreover, using a cell viability assay, we established that after 3 h of hypoxia, the accumulation of p53 results in a decreased number of the viable HCT-116^+/+ cells and the overexpression of miR-27a resulted in an increased number of viable HCT-116^+/+ cells with a concomitant decrease in p53 expression. Additionally, our data indicated that miR-27a and p53 depict inverse expression dynamics in 50% of the human colorectal cancer samples studied, when compared with that in the adjacent normal samples. Our data established that miR-27a and the tumor suppressor protein p53 are part of the same signaling network that has important implications during hypoxia and tumorigenesis.

MiR-454 prompts cell proliferation of human colorectal cancer cells by repressing CYLD expression

Previous studies have shown that miR-454 plays an important role in a variety of biological processes in various human cancer cells. However, the underlying mechanisms of this microRNA in colorectal cancer (CRC) cells remain largely unknown. In the present study, we investigated the miR-454 role in CRC cell proliferation. We found that miR-454 expression is markedly upregulated in CRC tissues and CRC cells compared with the matched tumor adjacent tissues and the FHC normal colonic cell line. Ectopic expression of miR-454 promoted the proliferation and anchorage-independent growth of CRC cells, whereas inhibition of miR-454 reduced this effect. Bioinformatics analysis further revealed cylindromatosis (CYLD), a putative tumor suppressor as a potential target of miR-454. Data from luciferase reporter assays showed that miR-454 directly binds to the 3'-untranslated region (3'-UTR) of CYLD mRNA and repressed expression at both transcriptional and translational levels. In functional assays, CYLD-silenced in miR-454-in-transfected SW480 cells have positive effect to promote cell proliferation, suggesting that direct CYLD downregulation is required for miR-454-induced CRC cell proliferation. In sum, our data provide compelling evidence that miR-454 functions as an onco-miRNA, playing a crucial role in the promoting cell proliferation in CRC, and its oncogenic effect is mediated chiefly through direct suppression of CYLD expression.

[MicroRNA expression profiles in squamous cell carcinomas of the meso- and hypopharynx]

INTRODUCTION

MicroRNAs play a role in carcinogenesis through their genome regulatory function.

AIM

The aim of the authors was to identify and compare microRNA expression signatures of meso- and hypopharynx squamous cell cancers on the basis of the cancer field hypothesis.

METHOD

Using standard mapping biopsy (tumour tissue and macroscopically normal tissues obtained 1, 2 and 3 cm from margin) 13 snap frozen sample series were analysed for microRNA expression with quantitative real-time polymerase chain reaction.

RESULTS

MiR-221 was significantly overexpressed in mesopharynx cancers, whole miR-21, miR-143 and miR-155 showed significant overexpression in hypopharynx cancers.

CONCLUSIONS

Using microRNA expression profiles the authors were able to distinguish peritumoural tissues according to distance from the primary tumour site. Future application of the method may prove to be useful in early detection of the altered epigenetic regulation in tissue fields representing normal phenotype. This may be helpful in cancer risk assessment and prevention.