MicroRNA expression profiling identifies miR-31-5p/3p as associated with time to progression in wild-type RAS metastatic colorectal cancer treated with cetuximab

Advances in microRNAs as Emerging Biomarkers for Colorectal Cancer Early Detection and Diagnosis

Colorectal cancer (CRC) remains the second most common cause of cancer-related mortality worldwide, necessitating advancements in early detection and innovative treatment strategies. MicroRNAs (miRNAs), small non-coding RNAs involved in gene regulation, have emerged as crucial players in the pathogenesis of CRC. This review synthesizes the latest findings on miRNA deregulated in precancerous lesions and in CRC. By examining the deregulation patterns of miRNAs across different stages of CRC development, this review highlights their potential as diagnostic tools. We specifically analyse the roles and diagnostic relevance of four miRNAs-miR-15b, miR-21, miR-31, and miR-146a-that consistently exhibit altered expression in CRC. The current knowledge of their role in key oncogenic pathways, drug resistance, and clinical relevance is discussed. Despite challenges posed by the heterogeneity of the research findings on miRNA deregulation and their role in CRC, integrating miRNA diagnostics into current screening methods holds promise for enhancing personalized medicine approaches. This review emphasizes the transformative potential of miRNAs in CRC diagnosis, paving the way for improved patient outcomes and novel therapeutic paradigms.

Whole exome sequencing and MicroRNA profiling of lung adenocarcinoma identified risk prediction features for tumors at stage I and its substages

OBJECTIVES

About 20% of stage I lung adenocarcinoma (LUAD) patients suffer a relapse after surgical resection. While finer substages have been defined and refined in the AJCC staging system, clinical investigations on the tumor molecular landscape are lacking.

MATERIALS AND METHODS

We performed whole exome sequencing, DNA copy number and microRNA profiling on paired tumor-normal samples from a cohort of 113 treatment-naïve stage I Taiwanese LUAD patients. We searched for molecular features associated with relapse-free survival (RFS) of stage I or its substages and validated the findings with an independent Caucasian LUAD cohort.

RESULTS

We found sixteen nonsynonymous mutations harbored at EGFR, KRAS, TP53, CTNNB1 and six other genes associated with poor RFS in a dose-dependent manner via variant allele fraction (VAF). An index, maxVAF, was constructed to quantify the overall mutation load from genes other than EGFR. High maxVAF scores discriminated a small group of high-risk LUAD at stage I (median RFS: 4.5 versus 69.5 months; HR = 10.5, 95% CI = 4.22-26.12, P < 0.001). At the substage level, higher risk was found for patients with high maxVAF or high miR-31; IA (median RFS: 32.1 versus 122.8 months, P = 0.005) and IB (median RFS: 7.1 versus 26.2, P = 0.049). MicroRNAs, miR-182, miR-183 and miR-196a were found correlated with EGFR mutation and poor RFS in stage IB patients.

CONCLUSION

Distinctive features of somatic gene mutation and microRNA expression of stage I LUAD are characterized to complement the survival prognosis by substaging. The findings open up more options for precision management of stage I LUAD patients.

Intermittent hypoxia BMSCs-derived exosomal miR-31-5p promotes lung adenocarcinoma development via WDR5-induced epithelial mesenchymal transition

BACKGROUND

Intermittent hypoxia (IH) is a factor involved in the incidence and progression of lung adenocarcinoma (LUAD). Bone marrow-derived bone mesenchymal stem cells (BMSCs)-derived exosomes are related to the promotion of tumor development. The objective of this experiment was to clarify the mechanism of exosomes from BMSCs in promoting the progression of LUAD induced by IH.

METHODS

This study examined if IH BMSCS-derived exosomes affect the malignancy of LUAD cells in vitro. Dual-luciferase assays were conducted to confirm the target of miR-31-5p with WD repeat domain 5 (WDR5). We further investigated whether or not  exosomal miR-31-5p or WDR5 could regulate epithelial-mesenchymal transition (EMT). We determined the effect of IH exosomes using a tumorigenesis model in vivo.

RESULTS

miR-31-5p entered into LUAD cells via exosomes. MiR-31-5p was greatly upregulated in IH BMSCs-derived exosomes compared with RA exosomes. Increased expression of exosomal miR-31-5p induced by IH was discovered to target WDR5 directly, increased activation of WDR5, and significantly facilitated EMT, thereby promoting LUAD progression.

CONCLUSIONS

The promoting effect of IH on LUAD is achieved partly through BMSCs-derived exosomal miR-31-5p triggering WDR5 and promoting EMT.

Identification of miRNA-mRNA Regulatory Networks Associated with Diabetic Retinopathy using Bioinformatics Analysis

INTRODUCTION

Diabetic retinopathy (DR) is a major complication of diabetes and a leading cause of visual loss. This study aimed to explore biomarkers for DR that may provide additional reference to DR pathogenesis and development.

METHODS

The differentially expressed genes (DEGs) between the DR and control samples in the GSE53257 dataset were identified. Logistics analyses were performed to identify DR-associated miRNAs and genes, and correlation analysis was performed to determine the correlation between them in GSE160306.

RESULTS

A total of 114 DEGs in DR were identified in GSE53257. Three genes, including ATP5A1 (down), DAUFV2 (down), and OXA1L (down), were differentially expressed between DR and control samples in GSE160306. Univariate logistics analysis identified that ATP5A1 (OR=0.007, p = 1.40E-02), NDUFV2 (OR = 0.003, p = 6.40E-03), and OXA1L (OR = 0.093, p = 3.08E-02) were DR-associated genes. ATP5A1 and OXA1L were regulated by multiple miRNAs, of which hsa-let- 7b-5p (OR = 26.071, p = 4.40E-03) and hsa-miR-31-5p (OR = 4.188, p = 5.09E-02) were related to DR. ATP5A1 and OXA1L were closely correlated with each other in DR.

CONCLUSION

The hsa-miR-31-5p-ATP5A1 and hsa-let-7b-5p-OXA1L axes might play novel and important roles in the pathogenesis and development of DR.

MiR-31-3p do not predict anti-EGFR efficacy in first-line therapy of RAS wild-type metastatic right-sided colon cancer

BACKGROUND

Low miR-31-3p expression was identified as predictive of anti-EGFR efficacy in RAS-wt mCRC. Primary tumor side was also proposed as a predictive factor of anti-EGFR benefit. This retrospective multicentric study evaluated the predictive role of miR-31-3p in right-sided RAS-wt mCRC patients treated with first-line CT+anti-EGFR or CT+bevacizumab (Beva).

METHODS

Seventy-two right-sided RAS-wt mCRC patients treated in first-line with CT+anti-EGFR (n = 43) or Beva (n = 29) were included. Overall survival (OS), progression-free survival (PFS) and response rate (RR) were analyzed and stratified according to tumor miR-31-3p expression level and targeted therapy (TT).

RESULTS

BRAF V600E mutation was more frequent in high vs low miR-31-3p expressers (60.6% vs 15.4%, P < 0.001). PFS was significantly longer with CT+Beva than with CT+anti-EGFR (13 vs 7 months; P = 0.024). Among low miR-31-3p expressers, PFS, OS and RR were not significantly different between the two groups, while in high miR-31-3p expressers, only PFS was longer in the CT+Beva group (11 vs 6 months; P = 0.03). In patients treated with CT+anti-EGFR, low miR-31-3p expressers had a significantly longer OS (20 vs 13 months; P = 0.02) than high miR-31-3p expressers. ORR was not significantly different between the two groups of treatment, in both low and high miR-31-3p expressers. MiR-31-3p expression status was statistically correlated between primary tumors and corresponding metastases.

CONCLUSION

In this study, miR-31-3p couldn't identify a subgroup of patients with right-sided RAS-wt mCRC who might benefit from anti-EGFR and suggest that Beva is the TT of choice in first-line treatment of these patients.

Non-coding RNAs as emerging regulators and biomarkers in colorectal cancer

CRC is the third most common cancer occurring worldwide and the second leading cause of cancer deaths. In the year 2020, 1,931,590 new cases of CRC and 935,173 deaths were reported. The last two decades have witnessed an intensive study of noncoding RNAs and their implications in various pathological conditions including cancer. Noncoding RNAs such as miRNAs, tsRNAs, piRNAs, lncRNAs, pseudogenes, and circRNAs have emerged as promising prognostic and diagnostic biomarkers in preclinical studies of cancer. Some of these noncoding RNAs have also been shown as promising therapeutic targets for cancer treatment. In this review, we have discussed the emerging roles of various types of noncoding RNAs in CRC and their future implications in colorectal cancer management and research.

MiroRNA-31-3p Promotes the Invasion and Metastasis of Non-Small-Cell Lung Cancer Cells by Targeting Forkhead Box 1 (FOXO1)

OBJECTIVE

To explore the possibility of microRNA miR-31-3p as a biomarker for bone metastasis of non-small-cell lung cancer (NSCLC) and its molecular mechanism to the invasion and metastasis of NSCLC cells.

METHODS

Real-time quantitative PCR (RT-qPCR) was used to detect the expression levels of miR-31-3p and forkhead box 1 (FOXO1) in NSCLC tissues, serum, and cells to analyze the correlation between the expression levels of miR-31-3p and the clinicopathology of NSCLC. After interference with or overexpressing miR-31-3p, NSCLC cell proliferation, apoptosis, invasion ability, and migration ability were detected by MTT, flow cytometry, Transwell, and scratch experiment, respectively. The interaction between miR-31-3p and FOXO1 was further verified by the dual-luciferase reporter experiment. Western blot was performed to detect the protein expression of FOXO1 in tissues and FOXO1, RhoA, p-RhoA, ROCK-2, and p-ROCK-2 in cells.

RESULTS

In tissues, serum, and NSCLC cell line A549 of the NSCLC patients, the expression of FOXO1 was notably lower, and the miR-31-3p expression was significantly higher. Overexpression of miR-31-3p could distinctly improve the proliferation, invasion, and migration of A549 cells, meanwhile inhibit cell apoptosis, and activate the RhoA/ROCK-2 signaling pathway, while interfering with the expression of miR-31-3p has the opposite function. Besides, bioinformatics analysis and luciferase reporter assay confirmed that FOXO1 was a target gene of miR-31-3p. Overexpressing FOXO1 could inhibit the proliferation and metastasis of A549 cells, but overexpressing miR-31-3p reverses the results.

CONCLUSION

This study confirmed that miR-31-3p promotes the proliferation, invasion, and migration of NSCLC cells and inhibits apoptosis through targeted regulating FOXO1 and be a potential therapeutic targets for the treatment of NSCLC.

The prognostic role of miR-31 in colorectal cancer: the results of a meta-analysis of 4720 patients

Aims: To study the association between miR-31 expression and clinical outcomes in colorectal cancer. Methods: A systematic search was performed and 16 studies were found eligible. To calculate the combined hazard ratio (HR), the DerSimonian and Laird random-effects model was used. Results: Pooled analysis revealed significant associations between high miR-31 expression and poor overall (HR: 0.68; 95% CI: 0.47-0.97; I²: 68.6%) and progression-free survival (HR: 0.49; 95% CI: 0.33-0.73; I²: 81.1%). High expressers were more likely to have a BRAF mutation. Therapeutic regimen and the mutational status significantly affected the observed associations. Conclusion: We identified that high miR-31 expression is associated with poor overall survival and progression-free survival and has a significant predictive value for anti-EGFR response.

MicroRNA31 and MMP-1 contribute to the differentiated pathway of invasion -with enhanced epithelial-to-mesenchymal transition- in squamous cell carcinoma of the skin

Epithelial to mesenchymal transition (EMT) is an important mechanism of invasion in cutaneous squamous cell carcinomas (cSCCs) and has been found to be enhanced in tumors originated from actinic keratosis with transformation limited to the basal epithelial layer -differentiated pathway-, compared to cases with invasion subsequent to complete epidermal transformation -classical pathway-. Several microRNAs and proteins can contribute to EMT modulation in cSCCs. MicroRNA21 and microRNA31 are involved in posttranscriptional regulation of protein expression and could play a relevant role in EMT and cSCC progression. Throughout the EMT process upregulation of matrix metalloproteinases (MMPs) enhances invasiveness and MMP-1 and MMP-3 contribute to local invasion, angiogenesis and metastasis in cSCCs. Additionally, cSCC development is associated with PTEN loss and NF-κB, NOTCH-1 and p63 activation. The aim of this work is to identify differences in the expression of those molecules between both pathways of cSCCs development. Eight tissue microarrays from 80 consecutive cSCCs were analyzed using LNA-based miRNA in situ hybridization for miRNA21 and miRNA31 evaluation, and immunohistochemistry for MMP-1, MMP-3, PTEN, NOTCH-1, NF-κB, p63 and CD31. Significantly higher expression of miRNA31 (p < 0.0001) and MMP-1 (p = 0.0072) and angiogenesis (p = 0.0199) were found in the differentiated pathway, whereas PTEN loss (p = 0.0430) was more marked in the classical pathway. No significant differences were found for the other markers. Our findings support a contribution of miRNA31 and MMP-1 in the differentiated pathway, associated to EMT and increased microvascularization. The greater PTEN loss in the classical pathway indicate that its relevance in cSCC is not EMT-related.

MicroRNA Expression Profiling of Lung Cancer with Differential Expression of the RON Receptor Tyrosine Kinase

Background

The Ron receptor tyrosine kinase (RON) can act as a protooncogene and may play a prominent role in the initiation and development of lung cancer. microRNAs (miRNA) are master regulators of gene expression through direct or indirect regulation, and impact all aspects of cell biology.

Methods

Nonsmall-cell lung cancer (NSCLC) samples and small-cell lung cancer (SCLC) were stratified based on RON expression to identify miRNA profiles associated with RON expression levels, differentially expressed miRNA regulated by RON were screened out, and their biological behavior was analyzed.

Results

miRNA expression was most significantly affected by cancer type, and we found 85 miRNAs that were significantly differentially expressed between NSCLC and SCLC. There were 46 miRNAs differentially expressed between high RON expressing NSCLC compared to low RON expressing NSCLC. Biological processes and pathways found to be significantly influenced by RON expression included epithelial-mesenchymal transition (EMT) and activation of the PI3K-Akt and MAPK signaling pathways.

Conclusions

These data may provide the basis for a novel strategy to characterize lung cancer by RON expression and microRNA genotyping.

Circular RNA circFAT1(e2) Promotes Colorectal Cancer Tumorigenesis via the miR-30e-5p/ITGA6 Axis

circRNAs (circular RNAs) are a family of noncoding RNAs and have diverse physiological and pathological functions. However, the functions and mechanisms of circRNAs in the development and progression of colorectal cancer (CRC) remain largely unknown. Here, we aimed to explore the functions and roles of circFAT1(e2) in CRC. qRT-PCR revealed that circFAT1(e2) in CRC tumor tissues was upregulated compared with that in adjacent normal tissues and was also upregulated in CRC cell lines. Small interfering RNAs (siRNAs) against circFAT1(e2) were used to decrease the expression of circFAT1(e2) in HCT116 and RKO cells in vitro. The roles of circFAT1(e2) in CRC cell metastasis and proliferation were then determined by transwell and CCK-8 assays. The results showed that circFAT1(e2) silencing markedly suppressed CRC growth. Moreover, we identified circFAT1(e2) as a promoter of CRC metastasis. Knockdown of circFAT1(e2) evidently reduced HCT116 and RKO cell migration and invasion. Furthermore, the regulatory relationship between circFAT1(e2) and its target miRNAs was verified by a luciferase reporter assay. We demonstrated that circFAT1(e2) could sponge miR-30e-5p, which regulated the expression level of integrin α6 (ITGA6), the downstream target gene of miR-30e-5p. Rescue assays demonstrated that knockdown of miR-30e-5p enhanced CRC proliferation and migration via ITGA6. Taken together, our results reveal the novel oncogenic roles of circFAT1(e2) in CRC through the miR-30e-5p/ITGA6 axis.

The Clinical Assessment of MicroRNA Diagnostic, Prognostic, and Theranostic Value in Colorectal Cancer

Simple Summary

MiRNAs are of great interest within colorectal cancers in diagnosis, prognosis, and within the field of personalized treatments; they are present within different biological fluids such as blood and can lead to specific information for daily clinical use. Herein, we review the current literature focusing on miRNAs as potential diagnostic and prognostic biomarkers in patients treated for colorectal cancers. Detection and analysis of miRNA expression are cost-effective and lead to high sensitivity and specificity rates. However, it is now necessary to highlight the most sensitive and specific miRNAs for each goal, either diagnostic, prognostic, or theranostic, thanks to multicentric prospective studies.

Abstract

MiRNAs have recently become a subject of great interest within cancers and especially colorectal cancers in diagnosis, prognosis, and therapy decisions; herein we review the current literature focusing on miRNAs in colorectal cancers, and we discuss future challenges to use this tool on a daily clinical basis. In liquid biopsies, miRNAs seem easily accessible and can give important information toward each step of the management of colorectal cancers. However, it is now necessary to highlight the most sensitive and specific miRNAs for each goal thanks to multicentric prospective studies. Conclusions: by their diversity and the feasibility of their use, miRNAs are getting part of the armamentarium of healthcare management of colorectal cancers.

Panitumumab and cetuximab affect differently miRNA expression in colorectal cancer cells

Background & aim: Resistance to anti-EGFR monoclonal antibodies in metastatic colorectal cancer (CRC) is frequent and prognostic biomarkers are lacking. MicroRNAs (miR) are good candidates in this context. We aimed to characterize cetuximab and panitumumab exposure influence on miR expression in colorectal cancer cells to identify those regulating the EGFR pathway and implicated in resistance to treatment. Finally, we aimed to identify miR expression in serum of patients with advanced CRC treated with cetuximab or panitumumab. Results: Cetuximab and panitumumab exposure induced significant expression variations of 17 miR out of a miRnome panel of 752. Six of those miR interacted with at least one downstream element of the EGFR pathway. Conclusion: After the bioinformatics two-phase process, five miR rarely described before could be potential actors of anti-EGFR monoclonal antibody resistance: miR-95-3p, miR-139-5p, miR-145-5p, miR-429 and miR-1247-5p. In vivo, we detected the expression of miR-139-5p and miR-145-5p in serum of patients with metastatic CRC.

MicroRNAs as Predictive Biomarkers of Resistance to Targeted Therapies in Gastrointestinal Tumors

The advent of precision therapies against specific gene alterations characterizing different neoplasms is revolutionizing the oncology field, opening novel treatment scenarios. However, the onset of resistance mechanisms put in place by the tumor is increasingly emerging, making the use of these drugs ineffective over time. Therefore, the search for indicators that can monitor the development of resistance mechanisms and above all ways to overcome it, is increasingly important. In this scenario, microRNAs are ideal candidate biomarkers, being crucial post-transcriptional regulators of gene expression with a well-known role in mediating mechanisms of drug resistance. Moreover, as microRNAs are stable molecules, easily detectable in tissues and biofluids, they are the ideal candidate biomarker to identify patients with primary resistance to a specific targeted therapy and those who have developed acquired resistance. The aim of this review is to summarize the major studies that have investigated the role of microRNAs as mediators of resistance to targeted therapies currently in use in gastro-intestinal neoplasms, namely anti-EGFR, anti-HER2 and anti-VEGF antibodies, small-molecule tyrosine kinase inhibitors and immune checkpoint inhibitors. For every microRNA and microRNA signature analyzed, the putative mechanisms underlying drug resistance were outlined and the potential to be translated in clinical practice was evaluated.

Molecular mechanisms and clinical implications of miRNAs in drug resistance of colorectal cancer

Systemic chemotherapy is identified as a curative approach to prolong the survival time of patients with colorectal cancer (CRC). Although great progress in therapeutic approaches has been achieved during the last decades, drug resistance still extensively persists and serves as a major hurdle to effective anticancer therapy for CRC. The mechanism of multidrug resistance remains unclear. Recently, mounting evidence suggests that a great number of microRNAs (miRNAs) may contribute to drug resistance in CRC. Certain of these miRNAs may thus be used as promising biomarkers for predicting drug response to chemotherapy or serve as potential targets to develop personalized therapy for patients with CRC. This review mainly summarizes recent advances in miRNAs and the molecular mechanisms underlying miRNA-mediated chemoresistance in CRC. We also discuss the potential role of drug resistance-related miRNAs as potential biomarkers (diagnostic and prognostic value) and envisage the future orientation and challenges in translating the findings on miRNA-mediated chemoresistance of CRC into clinical applications.

Distant Metastasis in Colorectal Cancer Patients-Do We Have New Predicting Clinicopathological and Molecular Biomarkers? A Comprehensive Review

Colorectal cancer (CRC) remains a serious health problem worldwide. Approximately half of patients will develop distant metastasis after CRC resection, usually with very poor prognosis afterwards. Because patient performance after distant metastasis surgery remains very heterogeneous, ranging from death within 2 years to a long-term cure, there is a clinical need for a precise risk stratification of patients to aid pre- and post-operative decisions. Furthermore, around 20% of identified CRC cases are at IV stage disease, known as a metastatic CRC (mCRC). In this review, we overview possible molecular and clinicopathological biomarkers that may provide prognostic and predictive information for patients with distant metastasis. These may comprise sidedness of the tumor, molecular profile and epigenetic characteristics of the primary tumor and arising metastatic CRC, and early markers reflecting cancer cell resistance in mCRC and biomarkers identified from transcriptome. This review discusses current stage in employment of these biomarkers in clinical practice as well as summarizes current experience in identifying predictive biomarkers in mCRC treatment.

KRAS-associated microRNAs in colorectal cancer

Colorectal cancer (CRC) is one of the leading causes of cancerrelated death worldwide. Despite progress in treatment of cancers, CRC with KRAS mutations are resistant towards anti-EGFR treatment. MicroRNAs have been discovered in an exponential manner within the last few years and have been known to exert either an onco-miRNA or tumor suppressive effect. Here, the various roles of microRNAs involved in the initiation and progression of KRAS-regulated CRC are summarized. A thorough understanding of the roles and functions of the plethora of microRNAs associated with KRAS in CRC will grant insights into the provision of other potential therapeutic targets as well as treatment. MicroRNAs may also serve as potential molecular classifier or early detection biomarkers for future treatment and diagnosis of CRC.

PathME: pathway based multi-modal sparse autoencoders for clustering of patient-level multi-omics data

Background

Recent years have witnessed an increasing interest in multi-omics data, because these data allow for better understanding complex diseases such as cancer on a molecular system level. In addition, multi-omics data increase the chance to robustly identify molecular patient sub-groups and hence open the door towards a better personalized treatment of diseases. Several methods have been proposed for unsupervised clustering of multi-omics data. However, a number of challenges remain, such as the magnitude of features and the large difference in dimensionality across different omics data sources.

Results

We propose a multi-modal sparse denoising autoencoder framework coupled with sparse non-negative matrix factorization to robustly cluster patients based on multi-omics data. The proposed model specifically leverages pathway information to effectively reduce the dimensionality of omics data into a pathway and patient specific score profile. In consequence, our method allows us to understand, which pathway is a feature of which particular patient cluster. Moreover, recently proposed machine learning techniques allow us to disentangle the specific impact of each individual omics feature on a pathway score. We applied our method to cluster patients in several cancer datasets using gene expression, miRNA expression, DNA methylation and CNVs, demonstrating the possibility to obtain biologically plausible disease subtypes characterized by specific molecular features. Comparison against several competing methods showed a competitive clustering performance. In addition, post-hoc analysis of somatic mutations and clinical data provided supporting evidence and interpretation of the identified clusters.

Conclusions

Our suggested multi-modal sparse denoising autoencoder approach allows for an effective and interpretable integration of multi-omics data on pathway level while addressing the high dimensional character of omics data. Patient specific pathway score profiles derived from our model allow for a robust identification of disease subgroups.

Upregulation of microRNA-31 is associated with poor prognosis in patients with advanced colorectal cancer

Colorectal cancer (CRC) manifests after the accumulation of genetic and epigenetic alterations along with tumor microenvironments. MicroRNA (miRNA/miR) molecules have been revealed to serve in critical roles in the progression various types of cancer, and their expression level is often an important diagnostic, predictive or prognostic biomarker. The aim of the present study was to evaluate the potential of miRNAs as prognostic biomarkers for patients with advanced CRC. miRNA arrays were performed on CRC specimens obtained from tumors with various molecular statuses [e.g. KRAS proto-oncogene, GTPase (KRAS)/B-Raf proto-oncogene, serine/threonine kinase (BRAF)/microsatellite instability (MSI)], and their paired normal mucosal specimens. The miRNA array revealed that miR-31-5p (miR-31) was specifically upregulated in CRCs with the BRAF V600E mutation, the results of which were supported by subsequent analysis of a dataset retrieved from The Cancer Genome Atlas (TCGA) database, which contained information regarding 170 patients with CRC including 51 BRAF-mutant CRCs. Of our cohort of 67 patients with stage IV CRC, 15 (22%) and 4 (6%) showed KRAS and BRAF V600E mutations, respectively. Since the median miR-31 expression was 3.45 (range, 0.004–6330.531), the cut-off value was chosen as 3.5, and all tumors were categorized into two groups accordingly (high-/low-miR-31 expression). The high miR-31 expression group (n=33) was significantly associated with a poorer mortality (univariate hazard ratio=2.12; 95% confidence interval, 0.23–0.95; P=0.03) and exhibited a shorter median survival time (MST; 20.1 months) compared with the low miR-31 expression group (n=34) (MST, 38.3 months; P=0.03), indicating that miR-31 is a promising prognostic biomarker for patients with advanced CRC. Thus, performing a functional analysis of miR-31 expression may lead to the development of new targeted therapies for the various genetic subtypes of CRC.

Prognostic and Predictive Molecular Biomarkers for Colorectal Cancer: Updates and Challenges

Colorectal cancer (CRC) is a leading cause of death among cancer patients. This heterogeneous disease is characterized by alterations in multiple molecular pathways throughout its development. Mutations in RAS, along with the mismatch repair gene deficiency, are currently routinely tested in clinics. Such biomarkers provide information for patient risk stratification and for the choice of the best treatment options. Nevertheless, reliable and powerful prognostic markers that can identify “high-risk” CRC patients, who might benefit from adjuvant chemotherapy, in early stages, are currently missing. To bridge this gap, genomic information has increasingly gained interest as a potential method for determining the risk of recurrence. However, due to several limitations of gene-based signatures, these have not yet been clinically implemented. In this review, we describe the different molecular markers in clinical use for CRC, highlight new markers that might become indispensable over the next years, discuss recently developed gene expression-based tests and highlight the challenges in biomarker research.

LncRNA miR503HG interacts with miR-31-5p through multiple ways to regulate cancer cell invasion and migration in ovarian cancer

The role of lncRNA miR503HG has been investigated in several types of cancer, but its functions in ovarian cancer (OC) is unclear. Analysis of TCGA dataset revealed a 50-fold lower expression level of miR503HG in OC tissues than that in non-tumor tissues, indicating the involvement of miR503HG in OC. Results in this study showed that miR503HG was downregulated in OC and predicted poor survival. Expression of miR503HG negatively correlated with the expression of miR-31-5p across OC and non-tumor tissues. RNA-RNA interaction analysis revealed that miR503HG can interact with miR-31-5p. Dual-luciferase assay showed that miR-31-5p and miR503HG may directly interact with each other. Methylation specific PCR (MSP) showed that overexpression of miR503HG led to increased methylation level of miR-31-5p gene. Transwell assay showed that overexpression of miR-31-5p resulted in increased invasion and migration rates of OC cells. Overexpression of MiR503HG played an opposite role and attenuated the effects of overexpressing miR-31-5p. Therefore, miR503HG may promote the methylation of miR-31-5p and serve as its sponge to inhibit OC cell invasion and migration.

Mechanisms of Innate and Acquired Resistance to Anti-EGFR Therapy: A Review of Current Knowledge with a Focus on Rechallenge Therapies

Innate and acquired resistance to anti-EGFR therapy (EGFRi) is a major limitation in the treatment of metastatic colorectal cancer (mCRC). Although RAS genes are the most commonly mutated innate and acquired oncogenes in cancer, there are a number of other mechanisms that limit the effectiveness of EGFRi. Patients with innate resistance have been found to contain BRAFV600E mutations, and possibly MET, MEK, PIK3CA, PTEN, and HER2 alterations. Meanwhile, BRAFV600E mutations may also be involved in acquired resistance to EGFRi, in addition to EGFR ectodomain mutations, MET alterations, and possibly HER2 amplification. In addition, paracrine effects and cell-fate mechanisms of resistance are being increasingly described as contributing to acquired resistance. Utilization of circulating tumor DNA has been paramount in monitoring the dynamic nature of acquired resistance and has helped to guide treatment decisions, particularly in the EGFRi rechallenge setting. Herein, we provide an in-depth review of EGFRi-resistance mechanisms and describe the current therapeutic landscape in the hopes of identifying effective rechallenge strategies.

Sema4C mediates EMT inducing chemotherapeutic resistance of miR-31-3p in cervical cancer cells

Sema4C, the target of many miRNAs, is involved in EMT-mediated chemotherapeutic resistance of many malignant tumors. However, the underlying upstream regulatory mechanisms of Sema4C-induced EMT and Sema4C-mediated drug resistance are still unclear. The aim of this study was to explore the potential role of miR-31-3p/Sema4C in regulating EMT in cisplatin-resistant (CR) cervical cancer cells. High expression levels of Sema4C were more frequently found in cervical cancer tissues and were associated with poor prognosis, whereas miR-31-3p was significantly downregulated in cervical cancer tissues, which was associated with shorter disease-free and overall survival. Overexpression of miR-31-3p inhibited malignant behaviors and EMT of cervical cancer cells in vitro. Furthermore, miR-31-3p was identified to directly target Sema4C, and upregulation of miR-31-3p reversed EMT-mediated biological functions, including cisplatin resistance of Sema4C in cervical cancer cells. These results suggest that Sema4C promoted EMT-mediated cisplatin resistance in cervical cancer cells and that this effect was inhibited by overexpression of miR-31-3p. Thus, silencing Sema4C or overexpression of miR-31-3p could be a novel approach to treat drug resistance to chemotherapy in cervical cancers.

Translational Potential of MicroRNAs for Preoperative Staging and Prediction of Chemoradiotherapy Response in Rectal Cancer

Colorectal cancer is the third most common cancer and the second cause of cancer-related deaths. Rectal cancer presents roughly one-third of all colorectal cancer cases and differs from it on both anatomical and molecular levels. While standard treatment of colon cancer patients is radical surgery, rectal cancer is usually treated with pre-operative chemoradiotherapy followed by total mesorectal excision, which requires precise estimation of TNM staging. Unfortunately, stage evaluation is based solely on imaging modalities, and they often do not correlate with postoperative pathological findings. Moreover, approximately half of rectal cancer patients do not respond to such pre-operative therapy, so they are exposed to its toxic effects without any clinical benefit. Thus, biomarkers that could precisely predict pre-operative TNM staging, and especially response to therapy, would significantly advance rectal cancer treatment—but till now, no such biomarker has been identified. In cancer research, microRNAs are emerging biomarkers due to their connection with carcinogenesis and exceptional stability. Circulating miRNAs are promising non-invasive biomarkers that could allow monitoring of a patient throughout the whole therapeutic process. This mini-review aims to summarize the current knowledge on miRNAs and circulating miRNAs involved in the prediction of response to treatment and pre-operative staging in rectal cancer patients.

miR-31-3p Expression and Benefit from Anti-EGFR Inhibitors in Metastatic Colorectal Cancer Patients Enrolled in the Prospective Phase II PROSPECT-C Trial

PURPOSE

Anti-EGFR mAbs are effective in the treatment of metastatic colorectal cancer (mCRC) patients. RAS status and tumor location (sidedness) are predictive markers of patients' response to anti-EGFR mAbs. Recently, low miR-31-3p expression levels have been correlated with clinical benefit from the anti-EGFR mAb cetuximab. Here, we aimed to validate the predictive power of miR-31-3p in a prospective cohort of chemorefractory mCRC patients treated with single-agent anti-EGFR mAbs.

EXPERIMENTAL DESIGN

miR-31-3p was tested by in situ hybridization (ISH) in 91 pretreatment core biopsies from metastatic deposits of 45 patients with mCRC. Sequential tissue biopsies obtained before treatment, at the time of partial response, and at disease progression were tested to monitor changes in miR-31-3p expression overtreatment. miR-31-3p expression, sidedness, and RAS status in pretreatment cell-free DNA were combined in multivariable regression models to assess the predictive value of each variable alone or in combination.

RESULTS

Patients with low miR-31-3p expression in pretreatment biopsies showed better overall response rate, as well as better progression-free survival and overall survival, compared to those with high miR-31-3p expression. The prognostic effect of miR-31-3p was independent from age, gender, and sidedness. No significant changes in the expression of miR-31-3p were observed when sequential tissue biopsies were tested in long-term or poor responders to anti-EGFR mAbs. miR-31-3p scores were similar when pretreatment biopsies were compared with treatment-naïve archival tissues (often primary colorectal cancer).

CONCLUSIONS

Our study validates the role of miR-31-3p as potential predictive biomarker of selection for anti-EGFR mAbs.

DNA methylation and chromatin modifiers in colorectal cancer

Colorectal carcinogenesis is a multistep process involving the accumulation of genetic alterations over time that ultimately leads to disease progression and metastasis. Binding of transcription factors to gene promoter regions alone cannot explain the complex regulation pattern of gene expression during this process. It is the chromatin structure that allows for a high grade of regulatory flexibility for gene expression. Posttranslational modifications on histone proteins such as acetylation, methylation, or phosphorylation determine the accessibility of transcription factors to DNA. DNA methylation, a chemical modification of DNA that modulates chromatin structure and gene transcription acts in concert with these chromatin conformation alterations. Another epigenetic mechanism regulating gene expression is represented by small non-coding RNAs. Only very recently epigenetic alterations have been included in molecular subtype classification of colorectal cancer (CRC). In this chapter, we will provide examples of the different epigenetic players, focus on their role for epithelial-mesenchymal transition and metastatic processes and discuss their prognostic value in CRC.

Downregulated microRNAs in the colorectal cancer: diagnostic and therapeutic perspectives

Colorectal cancer (CRC), the third most common cancer in the world, has no specific biomarkers that facilitate its diagnosis and subsequent treatment. The miRNAs, small single-stranded RNAs that repress the mRNA translation and trigger the mRNA degradation, show aberrant levels in the CRC, by which these molecules have been related with the initiation, progression, and drug-resistance of this cancer type. Numerous studies show the microRNAs influence the cellular mechanisms related to the cell cycle, differentiation, apoptosis, and migration of the cancer cells through the post-transcriptionally regulated gene expression. Specific patterns of the upregulated and down-regulated miRNA have been associated with the CRC diagnosis, prognosis, and therapeutic response. Concretely, the downregulated miRNAs represent attractive candidates, not only for the CRC diagnosis, but for the targeted therapies via the tumor-suppressing microRNA replacement. This review shows a general overview of the potential uses of the miRNAs in the CRC diagnosis, prognosis, and treatment with a special focus on the downregulated ones. [BMB Reports 2018; 51(11): 563-571].

Construction of prognostic microRNA signature for human invasive breast cancer by integrated analysis

Background

Despite the advances in early detection and treatment methods, breast cancer still has a high mortality rate, even in those patients predicted to have a good prognosis. The purpose of this study is to identify a microRNA signature that could better predict prognosis in breast cancer and add new insights to the current classification criteria.

Materials and methods

We downloaded microRNA sequencing data along with corresponding clinicopathological data from The Cancer Genome Atlas (TCGA). Of 1,098 breast cancer patients identified, 253 patients with fully characterized microRNA profiles were selected for analysis. A three-microRNA signature was generated in the training set. Subsequently, the performance of the signature was confirmed in a validation set. After construction of the signature, we conducted additional experiments, including flow cytometry and the Cell Counting Kit-8 assay, to illustrate the correlation of this microRNA signature with breast cancer cell cycle, apoptosis, and proliferation.

Results

Three microRNAs (hsa-mir-31, hsa-mir-16-2, and hsa-mir-484) were identified to be significantly and independently correlated with patient prognosis, and performed with good stability. Our results suggest that higher expression of hsa-mir-484 indicated worse prognosis, while higher expression of hsa-mir-31 and hsa-mir-16-2 indicated better prognosis. Moreover, additional experiments confirmed that this microRNA signature was related to breast cancer cell cycle and proliferation.

Conclusion

Our results indicate a three-microRNA signature that can accurately predict the prognosis of breast cancer, especially in basal-like and hormone receptor-positive breast cancer subtypes. We recommend more aggressive therapy and more frequent follow-up for high-risk groups.

Down-regulation of microRNA-31-5p inhibits proliferation and invasion of osteosarcoma cells through Wnt/β-catenin signaling pathway by enhancing AXIN1

OBJECTIVES

Recently, the role of microRNA-31-5p (miR-31-5p) in gene expression regulation has been reported in various cancers. Studies have shown that Wnt/β-catenin signaling pathway is involved in the proliferation and invasion of osteosarcoma (OS) cells. Therefore, this study aims to probe into the regulatory role of miR-31-5p targeting AXIN1 in OS cells through Wnt/β-catenin signaling pathway.

METHODS

Firstly, microarray expression profiles were used to screen differentially expressed miRNAs associated with OS. Next, OS and normal fibrous connective tissues as well as OS cell lines were obtained for investigating the role of miR-31-5p on OS. Then, the putative binding sites between miR-31-5p and AXIN1 were predicted and verified. The regulatory effects of miR-31-5p on proliferation and invasion as well as tumorigenic potential of OS cells targeting AXIN1 were also analyzed. Besides, the relationship between miR-31-5p and Wnt/β-catenin signaling pathway was assessed by immunofluorescence staining.

RESULTS

The microarray dataset GSE63939 showed that miR-31-5p and AXIN1 were involved in OS. miR-31-5p expression increased while the expression of AXIN1 decreased in OS tissues and cells. AXIN1 was identified as a target gene of miR-31-5p, intense expression of which inhibited the transcription of AXIN1. Down-regulated miR-31-5p suppressed proliferation, invasion and tumorigenicity of OS cells through promoting AXIN1. Decreased miR-31-5p activated Wnt/β-catenin signaling pathway, as reflected by increased β-catenin translocation into nuclei, through up-regulating the transcription of AXIN1.

CONCLUSIONS

All in all, repression of miR-31-5p targets AXIN1 to activate the Wnt/β-catenin signaling pathway, thus suppressing proliferation, invasion and tumorigenicity of OS cells.

The Developing Story of Predictive Biomarkers in Colorectal Cancer

Colorectal cancer (CRC) is the third most common malignancy worldwide. Surgery remains the most important treatment for non-metastatic CRC, and the administration of adjuvant chemotherapy depends mainly on the disease stage, which is still the strongest prognostic factor. A refined understanding of the genomics of CRC has recently been achieved thanks to the widespread use of next generation sequencing with potential future therapeutic implications. Microsatellite instability (MSI) has been suggested as a predictive marker for response to anti-programmed-cell-death protein 1 (PD-1) therapy in solid tumors, including CRC. It should be noted that not all cancers with MSI phenotype respond to anti-PD-1 immunotherapy, highlighting the urgent need for even better predictive biomarkers. Mitogen-Activated Protein Kinase (MAPK) pathway genes KRAS, NRAS, and BRAF represent important molecular targets and could serve as independent prognostic biomarkers in CRC, and identify those who potentially benefit from anti-epidermal growth factor receptor (EGFR) treatment. Emerging evidence has attributed a significant role to inflammatory markers including blood cell ratios in the prognosis and survival of CRC patients; these biomarkers can be easily assessed in routine blood exams and be used to identify high-risk patients or those more likely to benefit from chemotherapy, targeted therapies and potentially immunotherapy. Analysis of cell-free DNA (cfDNA), circulating tumor cells (CTC) and/or micro RNAs (miRNAs) could provide useful information for the early diagnosis of CRC, the identification of minimal residual disease and, the evaluation of the risk of recurrence in early CRC patients. Even the selection of patients suitable for the new targeted therapy is becoming possible with the use of predictive miRNA biomarkers. Finally, the development of treatment resistance with the emergence of chemo-resistance clones after treatment remains the most important challenge in the clinical practice. In this context it is crucial to identify potential biomarkers and therapeutic targets which could lead to development of new and more effective treatments.

MiR-31-5p promotes the cell growth, migration and invasion of colorectal cancer cells by targeting NUMB

The aim of this study was to investigate the role and specific molecular mechanism of miR-31-5 in colorectal cancer. The relative expression of miR-31-5p and NUMB in colorectal cancer tissues was analyzed by qRT-PCR. To knock down the expression of miR-31-5p, the transfection of miR-31-5p inhibitor was performed. The transfection with miR-31-5p mimic was used for miR-31-5p overexpression and pcDNA3.0-NUMB plasmid was used for NUMB overexpression. CCK-8 assay was used to analyze the cell proliferation. Flow cytometry was used to evaluate the cell apoptosis and cell cycle. Matrigel invasion assay was performed to assess the invasion potency and migration assay was performed to assess the migration potency. Hoechst 33258 staining assay was performed to analyze the cell apoptosis of HT29 cells after the indicated transfection. Luciferase activity assays were performed to confirmed the potential binding site for miR-31-5p in 3'-UTR region of NUMB. MiR-31-5p is highly expressed in colorectal cancer and is critical for the cell proliferation, cell cycle, migration, invasion and apoptosis. NUMB is target of miR-31-5p and NUMB overexpression inhibited the cell proliferation, migration, invasion and induced cell cycle arrest and apoptosis in HT29 colorectal cancer cells. In conclusion, miR-31-5p promoted the cell growth, migration and invasion by targeting NUMB in colorectal cancer cells.

Mapping of microRNAs related to cervical cancer in Latin American human genomic variants

Background: MicroRNAs are related to human cancers, including cervical cancer (CC) caused by HPV. In 2018, approximately 56.075 cases and 28.252 deaths from this cancer were registered in Latin America and the Caribbean according to GLOBOCAN reports. The main molecular mechanism of HPV in CC is related to integration of viral DNA into the hosts' genome. However, the different variants in the human genome can result in different integration mechanisms, specifically involving microRNAs (miRNAs). Methods: The miRNAs associated with CC were obtained from literature, the miRNA sequences and four human genome variants (HGV) from Latin American populations were obtained from miRBase and 1000 Genomes Browser, respectively. HPV integration sites near cell cycle regulatory genes were identified. miRNAs were mapped on HGV. miRSNPs were identified in the miRNA sequences located at HPV integration sites on the Latin American HGV.  Results: Two hundred seventy-two miRNAs associated with CC were identified in 139 reports from different geographic locations. By mapping with Blast-Like Alignment Tool (BLAT), 2028 binding sites were identified from these miRNAs on the human genome (version GRCh38/hg38); 42 miRNAs were located on unique integration sites; and miR-5095, miR-548c-5p and miR-548d-5p were involved with multiple genes related to the cell cycle. Thirty-seven miRNAs were mapped on the Latin American HGV (PUR, MXL, CLM and PEL), but only miR-11-3p, miR-31-3p, miR-107, miR-133a-3p, miR-133a-5p, miR-133b, miR-215-5p, miR-491-3p, miR-548d-5p and miR-944 were conserved. Conclusions: Ten miRNAs were conserved in the four HGV. In the remaining 27 miRNAs, substitutions, deletions or insertions were observed. These variation patterns can imply differentiated mechanisms towards each genomic variant in human populations because of specific genomic patterns and geographic features. These findings may help in determining susceptibility for CC development. Further identification of cellular genes and signalling pathways involved in CC progression could lead new therapeutic strategies based on miRNAs.

MicroRNA: A new player in response to therapy for colorectal cancer

Colorectal cancer (CRC) is one of the important malignancies that result in cancer-related deaths worldwide. Multiple lines of evidence have indicated that different responses to therapy in CRC cells led to the failure of the current therapies. Hence, identification of the underlying cellular and molecular pathways involved in the emergence of different responses from CRC cells could contribute to finding and designing new therapeutic platforms to overcome the present limitations. Among the various targets involved in CRC pathogenesis, microRNAs (miRNAs) have key roles in many signaling pathways that are associated with the initiation and progression of CRC. Increasing evidence has confirmed that miRNAs as epigenetic regulators could play critical roles in the response (resistance or sensitivity) to therapy. Cancer stem cells are well-known players in resistance to therapy in CRC. They have been shown to play significant roles via inhibition and activation of many miRNA networks. Hence, miRNAs could be involved in the resistance and sensitivity of therapy in CRC cells via affecting different mechanisms, such as activation of cancer stem cells. Here, we summarized the role of various miRNAs in response to therapy of CRC cells. Moreover, we highlighted the roles of these molecules in the function of cancer stem cells, which are known as important players in the resistance to therapy in CRC.

Validation of miR-31-3p Expression to Predict Cetuximab Efficacy When Used as First-Line Treatment in RAS Wild-Type Metastatic Colorectal Cancer

PURPOSE

MiR-31-3p expression has been shown to be associated with response to anti-EGFR therapy. We investigated the predictive role of this biomarker in the FIRE-3 study population, including its ability to differentiate outcomes between patients receiving anti-EGFR and anti-VEGF therapy.

EXPERIMENTAL DESIGN

MiR-31-3p expression was measured in primary tumors obtained from 340 patients with RAS WT mCRC enrolled in the FIRE-3 Trial. This included 164 patients randomized to receive FOLFIRI plus cetuximab (FOLFIRI+Cetux) and 176 to FOLFIRI plus bevacizumab (FOLFIRI+Beva). Patients were divided into subgroups defined by low or high miR-31-3p expression using a prespecified cut-off and by treatment arm. Analyses were performed to assess treatment efficacy by subgroup. Overall survival (OS) and progression-free survival (PFS) were analyzed using Kaplan-Meier curves and Cox regression models. Investigator-assessed objective response (iOR), early tumor shrinkage at 6 weeks (ETS), and centrally reviewed objective response (cOR) were analyzed using logistic regression models. The predictive value of miR-31-3p expression level was assessed through a treatment interaction test using multivariate models adjusted for potential confounding factors.

RESULTS

Low miR-31-3p expressers benefited from cetuximab compared with bevacizumab for PFS [HR, 0.74; 95% confidence interval (CI), 0.55-1.00; P = 0.05], OS (HR, 0.61; 95% CI, 0.41-0.88; P < 0.01), iOR (OR, 4.0; 95% CI, 1.9-8.2; P < 0.01), ETS (OR, 4.0; 95% CI, 2.1-7.7; P < 0.01 and cOR (OR, 4.9; 95% CI, 2.3-10.5; P < 0.01) in multivariate analyses. There was no difference in outcomes for high expressers between treatment arms. MiR-31-3p expression level was predictive of treatment effect for PFS (P = 0.03), OS (P = 0.05), iOR (P = 0.02), ETS (P = 0.04), and cOR (P < 0.01).

CONCLUSIONS

MiR-31-3p expression level was validated as a predictive biomarker of cetuximab therapy efficacy for patients with RAS WT mCRC.

MicroRNAs in the prognosis and therapy of colorectal cancer: From bench to bedside

MicroRNAs (miRNAs) are small, single-stranded, noncoding RNAs that can post-transcriptionally regulate the expression of various oncogenes and tumor suppressor genes. Dysregulated expression of many miRNAs have been shown to mediate the signaling pathways critical in the multistep carcinogenesis of colorectal cancer (CRC). MiRNAs are stable and protected from RNase-mediated degradation, thereby enabling its detection in biological fluids and archival tissues for biomarker studies. This review focuses on the role and application of miRNAs in the prognosis and therapy of CRC. While stage II CRC is potentially curable by surgical resection, a significant percentage of stage II CRC patients do develop recurrence. MiRNA biomarkers may be used to stratify such high-risk population for adjuvant chemotherapy to provide better prognoses. Growing evidence also suggests that miRNAs are involved in the metastatic process of CRC. Certain of these miRNAs may thus be used as prognostic biomarkers to identify patients more likely to have micro-metastasis, who could be monitored more closely after surgery and/or given more aggressive adjuvant chemotherapy. Intrinsic and acquired resistance to chemotherapy severely hinders successful chemotherapy in CRC treatment. Predictive miRNA biomarkers for response to chemotherapy may identify patients who will benefit the most from a particular regimen and also spare the patients from unnecessary side effects. Selection of patients to receive the new targeted therapy is becoming possible with the use of predictive miRNA biomarkers. Lastly, forced expression of tumor suppressor miRNA or silencing of oncogenic miRNA in tumors by gene therapy can also be adopted to treat CRC alone or in combination with other chemotherapeutic drugs.

microRNA profiling between Bacillus thuringiensis Cry1Ab-susceptible and -resistant European corn borer, Ostrinia nubilalis (Hübner)

Transgenic maize hybrids that express insecticidal Bacillus thuringiensis (Bt) crystalline (Cry) protein toxins effectively protect against the European corn borer, Ostrinia nubilalis, a devastating maize pest. Field monitoring and laboratory selections have detected varying levels of O. nubilalis resistance to Cry1Ab toxin. MicroRNAs (miRNAs) are short noncoding RNAs that are involved in post-transcriptional gene regulation. Their potential roles in the evolution of Bt resistance, however, remain largely unknown. Sequencing of small RNA libraries from the midgut of Cry1Ab-susceptible and resistant O. nubilalis larvae resulted in the discovery of 277 miRNAs, including 248 conserved and 29 novel. Comparative analyses of miRNA expression profiles between the laboratory strains predicted 26 and nine significantly up- and down-regulated transcripts, respectively, in the midgut of Cry1Ab resistant larvae. Amongst 15 differentially regulated miRNAs examined by quantitative real-time PCR, nine (60%) were validated as cosegregating with Cry1Ab resistance in a backcross progeny. Differentially expressed miRNAs were predicted to affect transcripts involved in cell membrane components with functions in metabolism and binding, and the putative Bt-resistance genes aminopeptidase N and cadherin. These results lay the foundation for future investigation of the potential role of miRNAs in the evolution of Bt resistance.

Prognostic value of microRNAs in colorectal cancer: a meta-analysis

Background

Numerous studies have shown that miRNA levels are closely related to the survival time of patients with colon, rectal, or colorectal cancer (CRC). However, the outcomes of different investigations have been inconsistent. Accordingly, a meta-analysis was conducted to study associations among the three types of cancers.

Materials and methods

Studies published in English that estimated the expression levels of miRNAs with survival curves in CRC were identified until May 20, 2017 by online searches in PubMed, Embase, Web of Science, and the Cochrane Library by two independent authors. Pooled HRs with 95% CIs were used to estimate the correlation between miRNA expression and overall survival.

Results

A total of 63 relevant articles regarding 13 different miRNAs, with 10,254 patients were ultimately included. CRC patients with high expression of blood miR141 (HR 2.52, 95% CI 1.68-3.77), tissue miR21 (HR 1.31, 95% CI 1.12-1.53), miR181a (HR 1.52, 95% CI 1.26-1.83), or miR224 (HR 2.12, 95% CI 1.04-4.34), or low expression of tissue miR126 (HR 1.55, 95% CI 1.24-1.93) had significantly poor overall survival (P<0.05).

Conclusion

In general, blood miR141 and tissue miR21, miR181a, miR224, and miR126 had significant prognostic value. Among these, blood miR141 and tissue miR224 were strong biomarkers of prognosis for CRC.

Technical Validation of a Reverse-Transcription Quantitative Polymerase Chain Reaction In Vitro Diagnostic Test for the Determination of MiR-31-3p Expression Levels in Formalin-Fixed Paraffin-Embedded Metastatic Colorectal Cancer Tumor Specimens

MiR-31-3p expression has been shown to be a predictive biomarker for response to anti-epithelial growth factor receptor therapy in patients with RAS wild-type metastatic colorectal cancer (mCRC). To aid in the quantification of miR-31-3p expression in formalin-fixed paraffin-embedded (FFPE) primary tumor samples from patients with mCRC, a reverse-transcription quantitative polymerase chain reaction (RT-qPCR) assay was developed and validated. Assay development included the identification of a microRNA reference standard and the determination of an appropriate relative quantification cutoff for differentiating low versus high miR-31-3p expression. Sample specimens for the validation studies included both FFPE slides and shavings. Polymerase chain reaction (PCR) efficiency and linearity, analytical sensitivity and specificity, assay robustness, reproducibility, and accuracy were demonstrated across a number of test conditions and differing quantitative PCR platforms. The data from this study provide evidence as to the feasibility of quantifying the expression of miR-31-3p from FFPE tumor tissue using a standardized RT-qPCR assay.

Genomic characterization of liver metastases from colorectal cancer patients

Metastatic dissemination is the most frequent cause of death of sporadic colorectal cancer (sCRC) patients. Genomic abnormalities which are potentially characteristic of such advanced stages of the disease are complex and so far, they have been poorly described and only partially understood. We evaluated the molecular heterogeneity of sCRC tumors based on simultaneous assessment of the overall GEP of both coding mRNA and non-coding RNA genes in primary sCRC tumor samples from 23 consecutive patients and their paired liver metastases. Liver metastases from the sCRC patients analyzed, systematically showed deregulated transcripts of those genes identified as also deregulated in their paired primary colorectal carcinomas. However, some transcripts were found to be specifically deregulated in liver metastases (vs. non-tumoral colorectal tissues) while expressed at normal levels in their primary tumors, reflecting either an increased genomic instability of metastatic cells or theiradaption to the liver microenvironment. Newly deregulated metastatic transcripts included overexpression of APOA1, HRG, UGT2B4, RBP4 and ADH4 mRNAS and the miR-3180-3p, miR-3197, miR-3178, miR-4793 and miR-4440 miRNAs, together with decreased expression of the IGKV1-39, IGKC, IGKV1-27, FABP4 and MYLK mRNAS and the miR-363, miR-1, miR-143, miR-27b and miR-28-5p miRNAs. Canonical pathways found to be specifically deregulated in liver metastatic samples included multiple genes related with intercellular adhesion and the metastatic processes (e.g., IGF1R, PIK3CA, PTEN and EGFR), endocytosis (e.g., the PDGFRA, SMAD2, ERBB3, PML and FGFR2), and the cell cycle (e.g., SMAD2, CCND2, E2F5 and MYC). Our results also highlighted the activation of genes associated with the TGFβ signaling pathway, -e.g. RHOA, SMAD2, SMAD4, SMAD5, SMAD6, BMPR1A, SMAD7 and MYC-, which thereby emerge as candidate genes to play an important role in CRC tumor metastasis.

MiR-31 regulates the cisplatin resistance by targeting Src in gallbladder cancer

Background

Gallbladder cancer (GBC) is a malignant tumor highly resistant to chemotherapy. MicroRNAs (miRNAs) are found extensively involved in modulation of carcinogenesis and chemoresistance. This study aimed to investigate cisplatin (DDP)-susceptibility regulated by expression of the miRNAs and underlying pathways in GBC.

Results

The microRNA-31 (miR-31) was selected by microarray due to the biggest fold change between DDP-resistant and parental cells. Ectopic overexpression of miR-31 decreased cell proliferation, viability and invasion capacity, but promoted apoptosis in DDP-resistant cells and in xenograft tumor models. Cell apoptosis and DDP-chemosensitivity was remarkably increased by knockdown of Src proto-oncogene (Src) expression, which was subsequently reversed by rescue of Src expression in miR-31-expressing cells.

Methods

The microarray was used to select the candidate miRNA in two DDP-resistant GBC cell lines. The effect of regulated expression of the miRNA on cell migration, invasion, proliferation and apoptosis was examined by wound healing, transwell assays, CCK-8 assays, colony formation and flow cytometry assays, respectively. Xenograft tumor models were used to validate the function of the downstream target.

Conclusion

Our results demonstrated that miR-31reduced significantly in GBC cells rendering resistance to cisplatin, and upregulated expression of miR-31 augmented chemosensitivity, presenting a therapeutic potential to overcome drug resistance in GBC.

Association of differential miRNA expression with hepatic vs. peritoneal metastatic spread in colorectal cancer

BACKGROUND

Though peritoneal carcinomatosis reflects a late stage of colorectal cancer (CRC), only few patients present with synchronous or metachronous liver metastases alongside their peritoneal carcinomatosis. It is hypothesized that this phenomenon may be causally linked to molecular characteristics of the primary CRC. This study used miRNA profiling of primary CRC tissue either metastasized to the liver, to the peritoneum or not metastasized at all thus to identify miRNAs potentially associated with defining the site of metastatic spread in CRC.

METHODS

Tissue of the primary tumor stemming from CRC patients diagnosed for either liver metastasis (LM; n = 10) or peritoneal carcinomatosis (PER; n = 10) was analyzed in this study. Advanced CRC cases without metastasis (M0; n = 3) were also included thus to select on those miRNAs most potentially associated with determining metastatic spread in general. miRNA profiling of 754 different miRNAs was performed in each group. MiRNAs being either differentially expressed comparing PER and LM or even triple differentially expressed (PER vs. LM vs. M0) were identified. Differentially expressed miRNAs were further validated by in silico and functional analysis.

RESULTS

Comparative analysis identified 41 miRNAs to be differentially expressed comparing primary tumors metastasized to the liver as opposed to those spread to the peritoneum. A set of 31 miRNAs was significantly induced in primary tumors that spread to the peritoneum (PER), while the remaining 10 miRNAs were found to be repressed. Out of these 41 miRNAs a number of 25 miRNAs was triple-differentially expressed (i.e. differentially expressed comparing LM vs. PER vs. M0). The latter underwent in silico analysis. Finally, we demonstrated that miR-31 down-regulated c-MET in DLD-1 colon cancer cells.

CONCLUSIONS

This study demonstrates that CRC primary tumors spread to the peritoneum vs. metastasized to the liver display significantly different miRNA profiles. Larger patient cohorts will be needed to validate whether determination of e.g. miR-31 may aid to predict the course of disease and whether this may help to create individualized follow up or treatment protocols. To determine whether certain miRNAs may be involved in regulating the metastatic potential of CRC, functional studies will be essential.

MiR-31a-5p protects myocardial cells against apoptosis by targeting Tp53

The pathogenesis and progression of heart failure (HF) involves multiple mechanisms, including the increased activity of the renin-angiotensin-aldosterone system, apoptosis and differential expression of microRNAs (miRNAs/miRs). Our previous study revealed an increase in miR‑31a‑5p levels in the failing hearts of a rat HF model. In the present study, whether and how miR‑31a‑5p mediates angiotensin II (AngII)‑induced apoptosis in the cardiac H9C2 cell line, was investigated using molecular biological approaches, including reverse transcription followed by quantitative polymerase chain reaction, western blotting, RNA arrays, and mutagenesis. It was demonstrated that AngII stimulation increased apoptosis and decreased miR‑31a‑5p expression, which coincided with increased tumor protein p53 (Tp53) levels. Overexpression of miR‑31a‑5p significantly suppressed the AngII‑induced apoptotic rate and caspase‑3 activity, while suppression of miR‑31a‑5p did the opposite. A total of 16 proapoptotic genes that were downregulated and 4 antiapoptotic genes that were upregulated in the miR‑31a‑5p‑overexpressed cells were identified. It was also revealed that Tp53 mRNA contained the seed sequence in its 3'‑untranslated region for miR‑31a‑5p binding. The luciferase reporter analysis showed that miR‑31a‑5p repressed the luciferase activity of the wild‑type seed sequence, but not the mutated seed sequence fused to a reporter construct. Thus, it was demonstrated that miR‑31a‑5p mediated AngII‑triggered apoptosis in myocardial cells at least partially through targeting Tp53. These findings advance the understanding of the functional interaction between miRNAs and Tp53 in the setting of cardiac diseases. Further work is required to explore whether miR‑31a‑5p can serve as a therapeutic target for HF treatment in vivo.

MicroRNA-31-3p Is Involved in Substance P (SP)-Associated Inflammation in Human Colonic Epithelial Cells and Experimental Colitis

Substance P (SP) mediates colitis. SP signaling regulates the expression of several miRNAs, including miR-31-3p, in human colonocytes. However, the role of miR-31-3p in colitis and the underlying mechanisms has not been elucidated. We performed real-time PCR analysis of miR-31-3p expression in human colonic epithelial cells overexpressing neurokinin-1 receptor (NCM460 NK-1R) in response to SP stimulation and in NCM460 cells after IL-6, IL8, tumor necrosis factor (TNF)-α, and interferon-γ exposure. Functions of miR-31-3p were tested in NCM460-NK-1R cells and the trinitrobenzene sulfonic acid (TNBS) and dextran sodium sulfate (DSS) models of colitis. Targets of miRNA-31-3p were confirmed by Western blot analysis and luciferase reporter assay. Jun N-terminal kinase inhibition decreased SP-induced miR-31-3p expression. miR-31-3p expression was increased in both TNBS- and DSS-induced colitis and human colonic biopsies from ulcerative colitis, compared with controls. Intracolonic administration of a miR-31-3p chemical inhibitor exacerbated TNBS- and DSS-induced colitis and increased colonic TNF-α, CXCL10, and chemokine (C-C motif) ligand 2 (CCL2) mRNA expression. Conversely, overexpression of miR-31-3p ameliorated the severity of DSS-induced colitis. Bioinformatic, luciferase reporter assay, and Western blot analyses identified RhoA as a target of miR-31-3p in NCM460 cells. Constitutive activation of RhoA led to increased expression of CCL2, IL6, TNF-α, and CXCL10 in NCM460-NK-1R cells on SP stimulation. Our results reveal a novel SP-miR-31-3p-RhoA pathway that protects from colitis. The use of miR-31-3p mimics may be a promising approach for colitis treatment.

Association between miR-31-3p expression and cetuximab efficacy in patients with KRAS wild-type metastatic colorectal cancer: a post-hoc analysis of the New EPOC trial

BACKGROUND

High miR-31-3p expression is associated with inferior outcomes in KRAS wild-type (WT) advanced colorectal cancer patients treated with anti-EGFR therapy. This study evaluated miR-31-3p expression in patients with operable colorectal liver metastases (LM) enrolled in the New EPOC study.

METHODS

MiR-31-3p expression was measured in primary tumors (PT) from 149 KRAS WT patients including 71 receiving chemotherapy alone (CT) and 78 receiving chemotherapy plus cetuximab (CTX). Each treatment arm was split into tertiles based on miR-31-3p expression levels. MiR-31-3p expression was also measured in LM from 94 patients with tumor tissue available.

RESULTS

The median progression-free survival for the combined populations with mid or high miR-31-3p expression was shorter in the CTX versus the CT arm (26.7 months versus 12.3 months, HR=2.28 95%CI 1.27; 4.09 p=0.006). Low miR-31-3p expressers had similar outcomes irrespective of treatment (HR=1.06 95%CI 0.43; 2.61 p=0.9). MiR-31-3p expression was correlated between paired PT and LM samples in the CT group but not in the CTX group.

CONCLUSIONS

Patients with low miR-31-3p expression in the New EPOC study were not harmed by the addition of cetuximab. This supports miR-31-3p as a promising predictive biomarker for anti-EGFR therapy in KRAS WT advanced colorectal cancer.

microRNAs Make the Call in Cancer Personalized Medicine

Since their discovery and the advent of RNA interference, microRNAs have drawn enormous attention because of their ubiquitous involvement in cellular pathways from life to death, from metabolism to communication. It is also widely accepted that they possess an undeniable role in cancer both as tumor suppressors and tumor promoters modulating cell proliferation and migration, epithelial-mesenchymal transition and tumor cell invasion and metastasis. Moreover, microRNAs can even affect the tumor surrounding environment influencing angiogenesis and immune system activation and recruitment. The tight association of microRNAs with several cancer-related processes makes them undoubtedly connected to the effect of specific cancer drugs inducing either resistance or sensitization. In this context, personalized medicine through microRNAs arose recently with the discovery of single nucleotide polymorphisms in the target binding sites, in the sequence of the microRNA itself or in microRNA biogenesis related genes, increasing risk, susceptibility and progression of multiple types of cancer in different sets of the population. The depicted scenario implies that the overall variation displayed by these small non-coding RNAs have an impact on patient-specific pharmacokinetics and pharmacodynamics of cancer drugs, pushing on a rising need of personalized treatment. Indeed, microRNAs from either tissues or liquid biopsies are also extensively studied as valuable biomarkers for disease early recognition, progression and prognosis. Despite microRNAs being intensively studied in recent years, a comprehensive review describing these topics all in one is missing. Here we report an up-to-date and critical summary of microRNAs as tools for better understanding personalized cancer biogenesis, evolution, diagnosis and treatment.

Electrical stimulation of adipose-derived mesenchymal stem cells and endothelial cells co-cultured in a conductive scaffold for potential orthopaedic applications

Electrical stimulation (ES) has emerged as a useful tool to regulate cell behaviour, but the effect of ES on mesenchymal stem cell (MSC)/vasculogenic cell co-culture has not been investigated. Herein, human adipose-derived MSCs (AD-MSCs) and umbilical vein endothelial cells (HUVECs) were co-cultured in an electrically conductive polypyrrole/chitosan scaffold. Compared with AD-MSC monoculture, calcium deposition in the co-culture without and with ES (200 μA for 4 h/day) was 139% and 346% higher, respectively, after 7 days. As the application of ES to AD-MSC monoculture only increased calcium deposition by 56% compared with that without ES after 7 days, these results indicate that ES and co-culture with HUVECs have synergistic effects on AD-MSCs' osteogenic differentiation. ES application also significantly enhanced CD31 expression of HUVECs. In HUVEC monoculture, application of ES increased CD31 expression by 224%, whereas the corresponding increase in AD-MSC/HUVEC co-culture with ES application was 62%. The gene expression results indicate that ES enhanced the cellular functions in AD-MSC and HUVEC monoculture via autocrine bone morphogenetic protein-2 (BMP-2) and vascular endothelial growth factor (VEGF), respectively. In co-culture, crosstalk between AD-MSCs and HUVECs due to paracrine BMP-2 and VEGF enhanced the cellular functions compared with the respective monoculture. With application of ES to the AD-MSC/HUVEC co-culture, autocrine signalling was enhanced, resulting in further promotion of cellular functions. These findings illustrate that co-culturing AD-MSC/HUVEC in a conductive scaffold with ES offers potential benefits for bone defect therapy.

MicroRNA-661 promotes non-small cell lung cancer progression by directly targeting RUNX3

Lung cancer is the primary cause of cancer‑associated mortality in men and women worldwide. Increasing evidence indicates that abnormal microRNA (miRNA) expression contributes to the carcinogenesis and progression of multiple human cancers, including non‑small cell lung cancer (NSCLC). Therefore, miRNAs exhibit the potential to act as biomarkers for the diagnosis, treatment and prognosis of human malignancies. miRNA‑661 (miR‑661) has previously been demonstrated to be important in the development of various human cancer types. However, the expression levels, functions and underlying mechanisms of miR‑661 in NSCLC remain to be elucidated. The present study demonstrated that miR‑661 was upregulated in NSCLC tissues and cell lines. In addition, miR‑661 expression levels were significantly correlated with differentiation and tumor stage lymph node metastasis of NSCLC patients. Functional experiments demonstrated that miR-661 downregulation inhibited NSCLC cell proliferation and invasion in vitro. Furthermore, runt‑related transcription factor 3 (RUNX3) was identified as a direct target of miR‑661 in NSCLC. RUNX3 was expressed at a low level in NSCLC tissues and was negatively correlated with the miR‑661 expression level. Further experiments revealed that RUNX3 knockdown significantly rescued the effects of miR‑661 underexpression on NSCLC cell proliferation and invasion. In conclusion, the present findings indicated a role for miR‑661 as an oncogene in NSCLC via direct targeting of RUNX3, thus suggesting that miR‑661 may be used to develop novel therapies for NSCLC patients.

Colorectal Cancer: From the Genetic Model to Posttranscriptional Regulation by Noncoding RNAs

Colorectal cancer is the third most common form of cancer in developed countries and, despite the improvements achieved in its treatment options, remains as one of the main causes of cancer-related death. In this review, we first focus on colorectal carcinogenesis and on the genetic and epigenetic alterations involved. In addition, noncoding RNAs have been shown to be important regulators of gene expression. We present a general overview of what is known about these molecules and their role and dysregulation in cancer, with a special focus on the biogenesis, characteristics, and function of microRNAs. These molecules are important regulators of carcinogenesis, progression, invasion, angiogenesis, and metastases in cancer, including colorectal cancer. For this reason, miRNAs can be used as potential biomarkers for diagnosis, prognosis, and efficacy of chemotherapeutic treatments, or even as therapeutic agents, or as targets by themselves. Thus, this review highlights the importance of miRNAs in the development, progression, diagnosis, and therapy of colorectal cancer and summarizes current therapeutic approaches for the treatment of colorectal cancer.