MiR-17-92 cluster is associated with 13q gain and c-myc expression during colorectal adenoma to adenocarcinoma progression

Unraveling the Multifaceted Role of the miR-17-92 Cluster in Colorectal Cancer: From Mechanisms to Biomarker Potential

Colorectal cancer (CRC) is a complex disease driven by intricate mechanisms, making it challenging to understand and manage. The miR-17-92 cluster has gained significant attention in CRC research due to its diverse functions and crucial role in various aspects of the disease. This cluster, consisting of multiple individual miRNAs, influences critical processes like tumor initiation, angiogenesis, metastasis, and the epithelial-mesenchymal transition (EMT). Beyond its roles in tumorigenesis and progression, miR-17-92's dysregulation in CRC has substantial implications for diagnosis, prognosis, and treatment, including chemotherapy responsiveness. It also shows promise as a diagnostic and prognostic biomarker, offering insights into treatment responses and disease progression. This review provides a comprehensive overview of recent advancements and the context-dependent role of the miR-17-92 cluster in colorectal cancer, drawing from the latest high-quality published data. It summarizes the established mechanisms governing miR-17-92 expression and the molecular pathways under its influence. Furthermore, it examines instances where it functions as an oncogene or a tumor suppressor, elucidating how cellular contexts dictate its biological effects. Ultimately, miR-17-92 holds promise as a biomarker for prognosis and therapy response, as well as a potential target for cancer prevention and therapeutic interventions. In essence, this review underscores the multifaceted nature of miR-17-92 in CRC research, offering promising avenues for enhancing the management of CRC patients.

Extrachromosomal circular MiR-17-92 amplicon promotes HCC

BACKGROUND AND AIMS

Extrachromosomal circular DNAs (eccDNAs) are prevalent in cancer genomes and emerge as a class of crucial yet less characterized oncogenic drivers. However, the structure, composition, genome-wide frequency, and contribution of eccDNAs in HCC, one of the most fatal and prevalent cancers, remain unexplored. In this study, we provide a comprehensive characterization of eccDNAs in human HCC and demonstrate an oncogenic role of microRNA (miRNA)-17-92-containing eccDNAs in tumor progression.

APPROACH AND RESULTS

Using the circle-sequencing method, we identify and characterize more than 230,000 eccDNAs from 4 paired samples of HCC tumor and adjacent nontumor liver tissues. EccDNAs are highly enriched in HCC tumors, preferentially originate from certain chromosomal hotspots, and are correlated with differential gene expression. Particularly, a series of eccDNAs carrying the miRNA-17-92 cluster are validated by outward PCR and Sanger sequencing. Quantitative PCR analyses reveal that miRNA-17-92-containing eccDNAs, along with the expression of their corresponding miRNAs, are elevated in HCC tumors and associated with poor outcomes and the age of HCC patients. More intriguingly, exogenous expression of artificial DNA circles harboring the miR-17-92 cluster, which is synthesized by the ligase-assisted minicircle accumulation method, can significantly accelerate HCC cell proliferation and migration.

CONCLUSIONS

These findings delineate the genome-wide eccDNAs profiling of HCC and highlight the functional significance of miRNA-containing eccDNAs in tumorigenesis, providing insight into HCC pathogenesis and cancer therapy, as well as eccDNA and miRNA biology.

MicroRNA therapeutics and nucleic acid nano-delivery systems in bacterial infection: a review

Bacteria that have worked with humans for thousands of years pose a major threat to human health even today, as drug resistance has become a prominent problem. Compared to conventional drug therapy, nucleic acid-based therapies are a promising and potential therapeutic strategy for diseases in which nucleic acids are delivered through a nucleic acid delivery system to regulate gene expression in specific cells, offering the possibility of curing intractable diseases that are difficult to treat at this stage. Among the many nucleic acid therapeutic ideas, microRNA, a class of small nucleic acids with special properties, has made great strides in biology and medicine in just over two decades, showing promise in preclinical drug development. In this review, we introduce recent advances in nucleic acid delivery systems and their clinical applications, highlighting the potential of nucleic acid therapies, especially miRNAs extracted from traditional herbs, in combination with the existing set of nucleic acid therapeutic systems, to potentially open up a new line of thought in the treatment of cancer, viruses, and especially bacterial infectious diseases.

Functional high-throughput screen identifies microRNAs that promote butyrate-induced death in colorectal cancer cells

The gut fermentation product butyrate displays anti-cancer properties in the human proximal colon, including the ability to inhibit proliferation and induce apoptosis in colorectal cancer (CRC) cells. A natural histone deacetylase inhibitor (HDACi), butyrate can alter histone acetylation patterns in CRC cells, and thereby regulate global gene expression, including the non-coding transcriptome and microRNAs (miRNAs). Dysregulated miRNA expression affects CRC development and progression; however, the interplay between miRNA activity and butyrate response remains to be elucidated. A high-throughput functional screen was employed to identify miRNAs that can act as enhancers of the anti-cancer properties of butyrate. Validation studies confirmed that several miRNAs, including miR-125b, miR-181a, miR-593, and miR-1227, enhanced apoptosis, decreased proliferation, and promoted cell-cycle arrest in the presence of butyrate. Pathway analyses of predicted miRNA target genes highlighted their likely involvement in critical cancer-related growth pathways, including WNT and PI3K signaling. Several cancer-associated miRNA targets, including TRIM29, COX2, PIK3R3, CCND1, MET, EEF2K, DVL3, and NUP62 were synergistically regulated by the combination of cognate miRNAs and butyrate. Overall, this study has exposed the potential of miRNAs to act as enhancers of the anti-cancer effects of HDAC inhibition and identifies specific miRNAs that might be exploited for therapeutic benefit.

Metabolic Pathways, Enzymes, and Metabolites: Opportunities in Cancer Therapy

Metabolic reprogramming enables cancer cells to proliferate and produce tumor biomass under a nutrient-deficient microenvironment and the stress of metabolic waste. A cancer cell adeptly undergoes a variety of adaptations in metabolic pathways and differential expression of metabolic enzyme genes. Metabolic adaptation is mainly determined by the physiological demands of the cancer cell of origin and the host tissue. Numerous metabolic regulators that assist cancer cell proliferation include uncontrolled anabolism/catabolism of glucose metabolism, fatty acids, amino acids metabolism, nucleotide metabolism, tumor suppressor genes, microRNAs, and many regulatory enzymes and genes. Using this paradigm, we review the current understanding of metabolic reprogramming in tumors and discuss the new strategies of cancer metabolomics that can be tapped into for cancer therapeutics.

Overexpression of the miR-17-92 cluster in colorectal adenoma organoids causes a carcinoma-like gene expression signature

Gain of chromosome arm 13q is one of the most prevalent DNA copy number alterations associated with colorectal adenoma-to-carcinoma progression. The oncogenic miR-17-92 cluster, located at 13q, was found to be overexpressed in colorectal cancer and in adenomas harboring 13q gain. However, to what extent overexpression of this group of microRNAs actually drives progression to cancer remains to be resolved. Therefore, we aimed to clarify the role of miR-17-92 cluster in the progression from colorectal adenoma to carcinoma.

The miR-17-92 cluster was overexpressed in human colorectal adenoma organoids without 13q gain and downstream effects on mRNA expression were investigated, along with functional consequences in vitro and in vivo.

Comparison of mRNA sequencing results of organoids overexpressing miR-17-92 and cultures transduced with control vector revealed a miR-17-92 expression signature. This signature appeared to be enriched in an independent series of colorectal cancers and adenomas with 13q gain, confirming that miR-17-92 expression is associated with malignant progression. However, tumor-associated characteristics, such as increased proliferation rate, were not observed in miR-17-92 overexpressing adenoma organoids in vitro. In addition, subcutaneous injection of these organoids in immunodeficient mice was insufficient to cause tumor outgrowth.

In conclusion, this study showed that miR-17-92 expression contributes to 13q gain-associated adenoma-to-carcinoma progression, however, this is insufficient to cause malignancy.

Muscarinic receptor activation in colon cancer selectively augments pro-proliferative microRNA-21, microRNA-221 and microRNA-222 expression

Overexpression of M3 subtype muscarinic receptors (M3R) hastens colon cancer progression. As microRNA (miRNA) expression is commonly dysregulated in cancer, we used microarrays to examine miRNA profiles in muscarinic receptor agonist-treated human colon cancer cells. We used quantitative RT-PCR (qPCR) to validate microarray results and examine miRNA expression in colon cancers and adjacent normal colon. These assays revealed that acetylcholine (ACh) treatment robustly induced miR-222 expression; miR-222 levels were three-fold higher in cancer compared to normal colon. In kinetic studies, ACh induced a 4.6-fold increase in pri-miR-222 levels within 1 h, while mature miR-222 increased gradually to 1.8-fold within 4 h. To identify post-M3R signaling mediating these actions, we used chemical inhibitors and agonists. ACh-induced increases in pri-miR-222 were attenuated by pre-incubating cells with atropine and inhibitors of protein kinase C (PKC) and p38 MAPK. Treatment with a PKC agonist, phorbol 12-myristate 13-acetate, increased pri-miR-222 levels, an effect blocked by PKC and p38 MAPK inhibitors, but not by atropine. Notably, treatment with ACh or transfection with miR-222 mimics increased cell proliferation; atropine blocked the effects of ACh but not miR-222. These findings identify a novel mechanism whereby post-M3R PKC/p38 MAPK signaling stimulates miR-222 expression and colon cancer cell proliferation.

MicroRNA-18 facilitates the stemness of gastric cancer by downregulating HMGB3 though targeting Meis2

The recurrence and metastasis of gastric cancer are related to the stemness of gastric cancer cells. Researches have shown that miR-18 level is negatively correlated to the occurrence and development of certain cancer types. However, the effects of miR-18 on the stemness of gastric cancer remain uncertain. In this research, gastric cancer cell lines with stable overexpression of miR-18 were constructed through lentivirus infection. CCK-8 assay, RT-qPCR, Western blot, flow cytometry, and in vivo tumorigenesis assays were performed to evaluate the effects of miR-18 on the stemness of gastric cancer cells. Moreover, luciferase reporter assays found that Meis2 was the target of miR-18. Furthermore, we also found that the low-expressed oncogene HMGB3 is involved in this miR-18/Meis2 axis to further promote the stemness of gastric cancer cells. These findings suggest that the miR-18/Meis2/HMGB3 axis may be potential prognostic indicators for patients with gastric cancer.

MicroRNAs and 'Sponging' Competitive Endogenous RNAs Dysregulated in Colorectal Cancer: Potential as Noninvasive Biomarkers and Therapeutic Targets

The gastrointestinal (GI) tract in mammals is comprised of dozens of cell types with varied functions, structures, and histological locations that respond in a myriad of ways to epigenetic and genetic factors, environmental cues, diet, and microbiota. The homeostatic functioning of these cells contained within this complex organ system has been shown to be highly regulated by the effect of microRNAs (miRNA). Multiple efforts have uncovered that these miRNAs are often tightly influential in either the suppression or overexpression of inflammatory, apoptotic, and differentiation-related genes and proteins in a variety of cell types in colorectal cancer (CRC). The early detection of CRC and other GI cancers can be difficult, attributable to the invasive nature of prophylactic colonoscopies. Additionally, the levels of miRNAs associated with CRC in biofluids can be contradictory and, therefore, must be considered in the context of other inhibiting competitive endogenous RNAs (ceRNA) such as lncRNAs and circRNAs. There is now a high demand for disease treatments and noninvasive screenings such as testing for bloodborne or fecal miRNAs and their inhibitors/targets. The breadth of this review encompasses current literature on well-established CRC-related miRNAs and the possibilities for their use as biomarkers in the diagnoses of this potentially fatal GI cancer.

PI3K-driven HER2 expression is a potential therapeutic target in colorectal cancer stem cells

OBJECTIVE

Cancer stem cells are responsible for tumour spreading and relapse. Human epidermal growth factor receptor 2 (HER2) expression is a negative prognostic factor in colorectal cancer (CRC) and a potential target in tumours carrying the gene amplification. Our aim was to define the expression of HER2 in colorectal cancer stem cells (CR-CSCs) and its possible role as therapeutic target in CRC resistant to anti- epidermal growth factor receptor (EGFR) therapy.

DESIGN

A collection of primary sphere cell cultures obtained from 60 CRC specimens was used to generate CR-CSC mouse avatars to preclinically validate therapeutic options. We also made use of the ChIP-seq analysis for transcriptional evaluation of HER2 activation and global RNA-seq to identify the mechanisms underlying therapy resistance.

RESULTS

Here we show that in CD44v6-positive CR-CSCs, high HER2 expression levels are associated with an activation of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway, which promotes the acetylation at the regulatory elements of the Erbb2 gene. HER2 targeting in combination with phosphatidylinositol 3-kinase (PI3K) and mitogen-activated protein kinase kinase (MEK) inhibitors induces CR-CSC death and regression of tumour xenografts, including those carrying Kras and Pik3ca mutation. Requirement for the triple targeting is due to the presence of cancer-associated fibroblasts, which release cytokines able to confer CR-CSC resistance to PI3K/AKT inhibitors. In contrast, targeting of PI3K/AKT as monotherapy is sufficient to kill liver-disseminating CR-CSCs in a model of adjuvant therapy.

CONCLUSIONS

While PI3K targeting kills liver-colonising CR-CSCs, the concomitant inhibition of PI3K, HER2 and MEK is required to induce regression of tumours resistant to anti-EGFR therapies. These data may provide a rationale for designing clinical trials in the adjuvant and metastatic setting.

Investigation of the role of the miR17-92 cluster in BMP9-induced osteoblast lineage commitment

BACKGROUND

Bone morphogenetic protein 9 (BMP9) has been identified as a crucial inducer of osteoblastic differentiation in mesenchymal stem cells (MSCs). Although microRNAs (miRNAs) are known to play a role in MSC osteogenesis, the mechanisms of action of miRNAs in BMP9-induced osteoblastic differentiation remain poorly understood.

METHODS

In this study, we investigate the possible role of the miR17-92 cluster in the BMP9-induced osteogenic differentiation of MSCs by using both in vitro and in vivo bone formation assays.

RESULTS

The results show that miR-17, a member of the miR17-92 cluster, significantly impairs BMP9-induced osteogenic differentiation. This impairment is effectively rescued by a miR-17 sponge, an antagomiR sequence against miR-17. Using TargetScan and the 3'-untranslated region luciferase reporter assays, we show that the direct target of miR-17 is the retinoblastoma gene (RB1), a gene that is pivotal to osteoblastic differentiation. We also confirm that RB1 is essential for the miR-17 effects on osteogenesis.

CONCLUSION

Our results indicate that miR-17 expression impairs normal osteogenesis by downregulating RB1 expression and significantly inhibiting the function of BMP9.

Small molecules with huge impacts: the role of miRNA-regulated PI3K pathway in human malignancies

Along with evolution, a considerable number of signaling cascades have evolved within cells to meet their multifaceted needs. Among transmitting molecules, phosphoinositide 3-kinase (PI3K), Akt, and mammalian target of rapamycin (mTOR) have teamed up to build a signaling axis that effectively regulates various cellular processes including cell proliferation and migration. Given the extensive output of the PI3K/Akt/mTOR signaling axis, its aberrancy could subsequently lead to the formation of a wide range of human cancers spanning from hematologic malignancies to different types of solid tumors. Despite the high frequency of the PI3K pathway over-activation in most malignancies, mutations in the DNA sequence are not equally common. Such incompatibility sheds light on the possible effects of post-translational modification mechanisms that may take control of this pathway, some of the most important ones of which are through microRNAs (miRNAs or miRs). The present review is designed to take off the veil from the regulatory role of these small non-coding RNAs on the PI3K/Akt/mTOR signaling axis in carcinogenesis.

MicroRNA expression in inflammatory bowel disease-associated colorectal cancer

MicroRNAs (miRNAs) are non-coding RNA molecules composed of 19–25 nucleotides that regulate gene expression and play a central role in the regulation of several immune-mediated disorders, including inflammatory bowel diseases (IBD). IBD, represented by ulcerative colitis and Crohn’s disease, is characterized by chronic intestinal inflammation associated with an increased risk of colorectal cancer (CRC). CRC is one of the most prevalent tumors in the world, and its main risk factors are obesity, physical inactivity, smoking, alcoholism, advanced age, and some eating habits, in addition to chronic intestinal inflammatory processes and the use of immunosuppressants administered to IBD patients. Recent studies have identified miRNAs associated with an increased risk of developing CRC in this population. The identification of miRNAs involved in this tumorigenic process could be useful to stratify cancer risk development for patients with IBD and to monitor and assess prognosis. Thus, the present review aimed to summarize the role of miRNAs as biomarkers for the diagnosis and prognosis of IBD-associated CRC. In the future, therapies based on miRNA modulation could be used both in clinical practice to achieve remission of the disease and restore the quality of life for patients with IBD, and to identify the patients with IBD at high risk for tumor development.

MYC Rules: Leading Glutamine Metabolism toward a Distinct Cancer Cell Phenotype

Simple Summary

In the last decade, metabolic reprogramming has emerged as a driving characteristic of cancer cells. The MYC oncogene, a transcription factor, has become of growing interest as a fundamental driver of differential cancer cell metabolism. Furthermore, the non-essential amino acid glutamine is deemed to be an important nutrient for cancer cells. In fact, glutamine can integrate into a wide variety of metabolic pathways, from energy metabolism to nucleotide synthesis. This review offers a comprehensive and specific overview of recent discoveries in the regulation of MYC oncogene activation on glutamine metabolism in cancer cells.

Abstract

Metabolic reprogramming and deregulated cellular energetics are hallmarks of cancer. The aberrant metabolism of cancer cells is thought to be the product of differential oncogene activation and tumor suppressor gene inactivation. MYC is one of the most important oncogenic drivers, its activation being reported in a variety of cancer types and sub-types, among which are the most prevalent and aggressive of all malignancies. This review aims to offer a comprehensive overview and highlight the importance of the c-Myc transcription factor on the regulation of metabolic pathways, in particular that of glutamine and glutaminolysis. Glutamine can be extensively metabolized into a variety of substrates and be integrated in a complex metabolic network inside the cell, from energy metabolism to nucleotide and non-essential amino acid synthesis. Together, understanding metabolic reprogramming and its underlying genetic makeup, such as MYC activation, allows for a better understanding of the cancer cell phenotype and thus of the potential vulnerabilities of cancers from a metabolic standpoint.

MicroRNA-Based Therapeutics for Drug-Resistant Colorectal Cancer

Although therapeutic approaches for patients with colorectal cancer (CRC) have improved in the past decades, the problem of drug resistance still persists and acts as a major obstacle for effective therapy. Many studies have shown that drug resistance is related to reduced drug uptake, modification of drug targets, and/or transformation of cell cycle checkpoints. A growing body of evidence indicates that several microRNAs (miRNAs) may contribute to the drug resistance to chemotherapy, targeted therapy, and immunotherapy by regulating the drug resistance-related target genes in CRC. These drug resistance-related miRNAs may be used as promising biomarkers for predicting drug response or as potential therapeutic targets for treating patients with CRC. In this review, we summarized the recent discoveries regarding anti-cancer drug-related miRNAs and their molecular mechanisms in CRC. Furthermore, we discussed the challenges associated with the clinical application of miRNAs as biomarkers for the diagnosis of drug-resistant patients and as therapeutic targets for CRC treatment.

The Role of miRNAs, miRNA Clusters, and isomiRs in Development of Cancer Stem Cell Populations in Colorectal Cancer

MicroRNAs (miRNAs or miRs) have a critical role in regulating stem cells (SCs) during development and altered expression can cause developmental defects and/or disease. Indeed, aberrant miRNA expression leads to wide-spread transcriptional dysregulation which has been linked to many cancers. Mounting evidence also indicates a role for miRNAs in the development of the cancer SC (CSC) phenotype. Our goal herein is to provide a review of: (i) current research on miRNAs and their targets in colorectal cancer (CRC), and (ii) miRNAs that are differentially expressed in colon CSCs. MicroRNAs can work in clusters or alone when targeting different SC genes to influence CSC phenotype. Accordingly, we discuss the specific miRNA cluster classifications and isomiRs that are predicted to target the ALDH1, CD166, BMI1, LRIG1, and LGR5 SC genes. miR-23b and miR-92A are of particular interest because our previously reported studies on miRNA expression in isolated normal versus malignant human colonic SCs showed that miR-23b and miR-92a are regulators of the LGR5 and LRIG1 SC genes, respectively. We also identify additional miRNAs whose expression inversely correlated with mRNA levels of their target genes and associated with CRC patient survival. Altogether, our deliberation on miRNAs, their clusters, and isomiRs in regulation of SC genes could provide insight into how dysregulation of miRNAs leads to the emergence of different CSC populations and SC overpopulation in CRC.

MicroRNAs as potential investigative and predictive biomarkers in colorectal cancer

Colorectal cancer (CRC) is a noticeable reason of cancer-associated deaths with a high incidence and mortality rate. Countless effort have been put into the improving clinical management of CRC patients including more effective tools and a wide variety of biomarkers for diagnostic, prognostic or predictive purposes. In recent years, dysregulated miRNAs have been emerged as highly sensitive and specific markers to manage CRC in an effective way. They can play key roles in carcinogenesis as potential oncogenes, tumor suppressors or regulators of cancer network. Therefore, miRNAs may serve as molecular tools that can be quantified and used in diagnostic and prognostic approaches. Growing evidence also suggests that forced expression of tumor suppressor miRNAs or inhibiting the oncogene ones, can be used as a novel treatment strategy. In this review, we focus on the clinical applications of miRNAs as promising biomarkers of early cancer detection, prognosis and treatment.

Dissecting miRNA signature in colorectal cancer progression and metastasis

Colorectal cancer (CRC) is the third most common cancer and leading cause of cancer related deaths worldwide. Despite recent advancements in surgical and molecular targeted therapies that improved the therapeutic efficacy in CRC, the 5 years survival rate of CRC patients still remains frustratingly poor. Accumulated evidences indicate that microRNAs (miRNAs) play a crucial role in the progression and metastasis of CRC. Dysregulated miRNAs are closely associated with cancerous phenotypes (e.g. enhanced proliferative and invasive ability, evasion of apoptosis, cell cycle aberration, and promotion of angiogenesis) by regulating their target genes. In this review, we provide an updated overview of tumor suppressive and oncogenic miRNAs, circulatory miRNAs, and the possible causes of dysregulated miRNAs in CRC. In addition, we discuss the important functions of miRNAs in drug resistance of CRC.

Prognostic value of BRAF/MIR-17 signature and B-Raf protein expression in patients with colorectal cancer: A pilot study

Background

Despite the recent improvement in colorectal cancer (CRC) treatment, it still has a poor prognosis with a low survival rate. Genetic and epigenetic mechanisms have proved to play a substantial role in CRC tumorigenesis and progression. According to Gene Ontology and TargetScan analyses, the B‐Raf proto‐oncogene (BRAF) gene is one of the microRNA‐17 (miR‐17) targets. We aimed to explore the prognostic value of B‐Raf protein and BRAF/microRNA‐17 (MIR‐17) gene expression signature in CRC archived samples.

Methods

B‐Raf protein expression was identified by immunohistochemistry, while gene expression studies were quantified by real‐time qPCR in 53 paired archived CRC specimens.

Results

The BRAF showed higher expressions in CRC specimens relative to non‐cancer tissues (p = 0.006). MIR17 expression was inversely and significantly correlated with both B‐Raf protein (r = −0.79, p < 0.001) and gene expression (r = −0.35, p = 0.010) and showed a significant direct correlation with a high rate of relapse (p = 0.020). BRAF/miR‐17 expression in CRC was associated inversely with tumor size, high grade of colonic carcinoma, lymph node metastasis, and carcinoma subtype. Spearman correlation and Kaplan‐Meier survival curve analyses revealed that disease‐free survival and overall survival were inversely and significantly correlated with positive B‐Raf protein expression (r = −0.31 and −0.35, p = 0.023 and 0.011, respectively) and directly correlated with log BRAF/MIR17 ratio (r = 0.50 and 0.41, p < 0.001 and = 0.003, respectively). Cox hazard regression analysis revealed the BRAF/MIR17 ratio could predict both types of patients' survival, among other variables.

Conclusion

BRAF/MIR17 ratio could have prognostic utility in patients with CRC. Further larger‐scale studies are warranted to confirm this utility.

MicroRNAs Regulate Intestinal Immunity and Gut Microbiota for Gastrointestinal Health: A Comprehensive Review

MicroRNAs are small non-coding RNAs regulating gene expression at the post-transcriptional level. The regulation of microRNA expression in the gut intestine is gradually recognized as one of the crucial contributors of intestinal homeostasis and overall health. Recent studies indicated that both the microRNAs endogenous in the gut intestine and exogenous from diets could play influential roles in modulating microbial colonization and intestinal immunity. In this review, we discuss the biological functions of microRNAs in regulating intestinal homeostasis by modulating intestinal immune responses and gut microbiota. We particularly focus on addressing the microRNA-dependent communication and interactions among microRNA, gut microbiota, and intestinal immune system. Besides, we also summarize the roles of diet-derived microRNAs in host-microbiome homeostasis and their benefits on intestinal health. A better understanding of the relationships among intestinal disorders, microRNAs, and other factors influencing intestinal health can facilitate the application of microRNA-based therapeutics for gastrointestinal diseases.

Dysregulation of microRNA expression during the progression of colorectal tumors

MicroRNAs (miRNAs) are potential biomarkers of neoplastic lesions, but additional information on dysregulated miRNA expression during progression of the adenoma-adenocarcinoma sequence may be helpful to identify the role of miRNAs in this sequence. We examined the expression levels of 13 miRNAs (hsa-miRNA-19a-3p, hsa-miRNA-21-5p, hsa-miRNA-27a-3p, hsa-miRNA-27b-3p, hsa-miRNA-31-5p, hsa-miRNA-34b-3p, hsa-miRNA-125b-5p, hsa-miRNA-143-3p, miRNA-191-5p, hsa-miRNA-193b-3p, hsa-miRNA-195-5p, hsa-miRNA-206 and hsa-let-7a-5p) that are closely associated with colorectal carcinogenesis in 40 conventional adenomas (tubular and tubulovillous adenomas), 20 intramucosal carcinomas (IMCs) and 60 invasive colorectal cancers (iCRCs) using reverse-transcription polymerase chain reaction. These 120 tumors were divided into two cohorts, that is, cohort 1 (60 cases) and cohort 2 (for validation; 60 cases). We analyzed the expression levels of these miRNAs in the first step (adenoma→IMC) and second step IMC→iCRC) of the adenoma-carcinoma sequence in both cohorts. Although no significant differences in the expression of any of the 13 miRNAs were found between adenomas and IMCs consistently in both cohorts, the expression levels of hsa-miRNA-125b-5p, hsa-miRNA-143-3p, and hsa-miRNA-206 were significantly upregulated in iCRC in both cohorts compared with those in IMC. The current results suggest that certain miRNAs, including hsa-miRNA-125b-5p, hsa-miRNA-143-3p and hsa-miRNA-206, are candidate markers that play critical roles in the progression of IMC to iCRC.

Good or not good: Role of miR-18a in cancer biology

miR-18a is a member of primary transcript called miR-17-92a (C13orf25 or MIR17HG) which also contains five other miRNAs: miR-17, miR-19a, miR-20a, miR-19b and miR-92a. This cluster as a whole shows specific characteristics, where miR-18a seems to be unique. In contrast to the other members, the expression of miR-18a is additionally controlled and probably functions as its own internal controller of the cluster. miR-18a regulates many genes involved in proliferation, cell cycle, apoptosis, response to different kinds of stress, autophagy and differentiation. The disturbances of miR-18a expression are observed in cancer as well as in different diseases or pathological states. The miR-17-92a cluster is commonly described as oncogenic and it is known as 'oncomiR-1', but this statement is a simplification because miR-18a can act both as an oncogene and a suppressor. In this review we summarize the current knowledge about miR-18a focusing on its regulation, role in cancer biology and utility as a potential biomarker.

Tumor Tissue MIR92a and Plasma MIRs21 and 29a as Predictive Biomarkers Associated with Clinicopathological Features and Surgical Resection in a Prospective Study on Colorectal Cancer Patients

Cancer-related microRNAs (miRNAs) are emerging as non-invasive biomarkers for colorectal cancer (CRC). This study aimed to analyze the correlation between the levels of tissue and plasma miRNAs and clinicopathological characteristics and surgical resection. This study was a prospective study of CRC patients who underwent surgery. Forty-four sample pairs of tissue and plasma were analyzed. The miRNA levels were evaluated by RT-qPCR. The level of tumor tissue MIR92a showed a significant difference in CRC with lymph node metastasis, stage ≥ III, and high lymphatic invasion. In preoperative plasma, there were significant differences in CRC with stage ≥ III (MIR29a) and perineural invasion (MIR21). In multivariate analysis of lymphatic invasion, the levels of both preoperative plasma MIR29a and tumor tissue MIR92a showed significant differences. Furthermore, in cases with higher plasma miRNA level, the levels of plasma MIRs21 and 29a were significantly decreased after the operation. In this study, there were significant differences in miRNAs levels with respect to the sample type, clinicopathological features, and surgical resection. The levels of tumor tissue MIR92a and preoperative plasma MIR29a may have the potential as a biomarker for prognosis. The plasma MIRs21 and 29a level has the potential to be a predictive biomarker for treatment efficacy.

The roles of miRNAs' clinical efficiencies in the colorectal cancer pathobiology: A review article

MiRNAs (microRNAs) are defined as micro directors and regulators of gene expression. Since altered miRNA expression is signified in the pathobiology of diverse cancers such as colorectal cancers (CRCs), these molecules are described as therapeutic targets, either. Manipulation of miRNAs could lead to further therapy for chemo and radio-resistant CRCs. The usage of microRNAs has indicated prominent promise in the prognosis and diagnosis of CRC, because of their unique expression pattern associated with cancer types and malignancies. Nowadays, many researchers are analyzing the correlation between miRNA polymorphisms and cancer risk. With continuous incompatibility in colorectal cancer (CRC) miRNAs expression data, it is critical to move toward the content of a "pre-laboratory" analysis to speed up efficient accuracy medicine and translational study. Pathway study for the highest expressed miRNAs- regulated target genes resulted in the identification of a considerable number of genes associated with CRC pathway including PI3K, TGFβ, and APC. In this review, we aimed to collect fruitful information about miRNAs and their potential roles in CRC, and provide a meta-analysis of the most frequently studied miRNAs in association with the disease.

Colorectal Adenomas-Genetics and Searching for New Molecular Screening Biomarkers

Colorectal cancer (CRC) is a malignant disease with an incidence of over 1.8 million new cases per year worldwide. CRC outcome is closely related to the respective stage of CRC and is more favorable at less advanced stages. Detection of early colorectal adenomas is the key to survival. In spite of implemented screening programs showing efficiency in the detection of early precancerous lesions and CRC in asymptomatic patients, a significant number of patients are still diagnosed in advanced stages. Research on CRC accomplished during the last decade has improved our understanding of the etiology and development of colorectal adenomas and revealed weaknesses in the general approach to their detection and elimination. Recent studies seek to find a reliable non-invasive biomarker detectable even in the blood. New candidate biomarkers could be selected on the basis of so-called liquid biopsy, such as long non-coding RNA, microRNA, circulating cell-free DNA, circulating tumor cells, and inflammatory factors released from the adenoma into circulation. In this work, we focused on both genetic and epigenetic changes associated with the development of colorectal adenomas into colorectal carcinoma and we also discuss new possible biomarkers that are detectable even in adenomas prior to cancer development.

Diagnostic Value of Combining miRNAs, CEA Measurement and the FOBT in Colorectal Cancer Screening

Introduction

Colorectal cancer (CRC) is one of the most common illnesses that seriously threatens human health; many papers have reported that microRNAs (miRNAs) are promising biomarkers for cancer detection. However, miRNAs have not been used in clinical practice even though they are superior to the currently used screening tools, such as the fecal occult blood test (FOBT) and carcinoembryonic antigen (CEA) measurement.

Methods

In this study, we focused on the usefulness of a panel of miRNAs and the combination of miRNAs with the FOBT and CEA measurement, the currently used general diagnosis methods, to improve the accuracy of CRC diagnosis.

Results

The results showed that the miRNA panel has great potential value as a diagnostic biomarker with high specificity and sensitivity, and further analysis demonstrated that the miRNA panel had higher sensitivity and specificity than the FOBT and CEA measurement, even when these methods were combined. More importantly, although the miRNA panel is superior to the FOBT and CEA measurement, it cannot replace them.

Conclusions

In this research, we investigated whether complementarity exists between the miRNA panel and the FOBT and CEA measurement for CRC diagnosis. Interestingly, the results indicated that the FOBT and CEA measurement could improve the positivity rate of the miRNA panel as a biomarker and vice versa.

Overexpression of miR-17 is correlated with liver metastasis in colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is the second leading cause of cancer-related deaths in men and women. The presence of systemic disease, with metastatic spread to distant sites such as the liver, considerably reduces the survival rate in CRC. Cancer stem cells contribute to the metastatic potential of CRC. However, the mechanism underlying metastasis in CRC remains unclear. Thus, this study aimed to examine the expression of microRNAs (miRNAs) in CRC stem cells in cases of liver metastases and assess their correlation with clinicopathological features.

METHODS

miRNAs showing high expression in liver metastases and primary lesions were selected through data mining of gene expression omnibus datasets, and miRNAs characteristic of stem cells were selected through COREMINE medical text mining. Subsequently, paired formalin-fixed paraffin-embedded tissue samples of primary CRC and liver metastasis from 30 patients were examined for the expression of miRNAs common to these lists (hsa-miR-20a, hsa-miR-26b, hsa-miR-146a, hsa-miR-17, hsa-miR-451, hsa-miR-23a, and hsa-miR-29a) using quantitative real-time polymerase chain reaction. Further, miRNA expression was compared between liver metastases and the primary tumor in each patient and the factors associated with differential expression were analyzed.

RESULTS

hsa-miR-17 was significantly upregulated in liver metastases (P < .05), but no significant difference in the expression of hsa-miR-26b, hsa-miR-146a, hsa-miR-451, hsa-miR-23a, and hsa-miR-29a was observed between primary tumors and liver metastases. The higher expression of hsa-miR-17 in liver metastases was associated with the administration of neoadjuvant chemotherapy and tumor differentiation (P < .05) but was not associated with age, sex, tumor location, or lymphatic metastasis.

CONCLUSIONS

High expression of miR-17 may contribute to liver metastasis in CRC. Therefore, an in-depth understanding of its downstream pathways could help in elucidating the mechanisms underlying liver metastases in CRC. However, additional studies are warranted to validate these findings.

Focused screening reveals functional effects of microRNAs differentially expressed in colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is still a leading cause of death worldwide. Recent studies have pointed to an important role of microRNAs in carcinogenesis. Several microRNAs are described as aberrantly expressed in CRC tissues and in the serum of patients. However, functional outcomes of microRNA aberrant expression still need to be explored at the cellular level. Here, we aimed to investigate the effects of microRNAs aberrantly expressed in CRC samples in the proliferation and cell death of a CRC cell line.

METHODS

We transfected 31 microRNA mimics into HCT116 cells. Total number of live propidium iodide negative (PI-) and dead (PI+) cells were measured 4 days post-transfection by using a high content screening (HCS) approach. HCS was further used to evaluate apoptosis (via Annexin V and PI staining), and to discern between intrinsic and extrinsic apoptotic pathways, by detecting cleaved Caspase 9 and 8, respectively. To reveal mRNA targets and potentially involved mechanisms, we performed microarray gene expression and functional pathway enrichment analysis. Quantitative PCR and western blot were used to validate potential mRNA targets.

RESULTS

Twenty microRNAs altered the proliferation of HCT116 cells in comparison to control. miR-22-3p, miR-24-3p, and miR-101-3p significantly repressed cell proliferation and induced cell death. Interestingly, all anti-proliferative microRNAs in our study had been previously described as poorly expressed in the CRC samples. Predicted miR-101-3p targets that were also downregulated by in our microarray were enriched for genes associated with Wnt and cancer pathways, including MCL-1, a member of the BCL-2 family, involved in apoptosis. Interestingly, miR-101-3p preferentially downregulated the long anti-apoptotic MCL-1 L isoform, and reduced cell survival specifically by activating the intrinsic apoptosis pathway. Moreover, miR-101-3p also downregulated IL6ST, STAT3A/B, and MYC mRNA levels, genes associated with stemness properties of CRC cells.

CONCLUSIONS

microRNAs upregulated in CRC tend to induce proliferation in vitro, whereas microRNAs poorly expressed in CRC halt proliferation and induce cell death. We provide novel evidence linking preferential inhibition of the anti-apoptotic MCL-1 L isoform by miR-101-3p and consequent activation of the intrinsic apoptotic pathway as potential mechanisms for its antitumoral activity, likely due to the inhibition of the IL-6/JAK/STAT signaling pathway.

Roles of microRNAs as non-invasive biomarker and therapeutic target in colorectal cancer

MicroRNAs are endogenous, short non-coding RNA molecules that function as critical regulators of various biological processes. There is a strong functional evidence linking the involvement of dysregulated miRNAs to the occurrence, development and progression of colorectal cancer. Studies indicate that while overexpression of oncomiRs, and repression of tumor suppressor miRNAs tends to drive the overall tumorigenic process, the global picture of aberrant miRNA expression in colorectal cancer can classify the disease into multiple molecular phenotypes. Moreover, the expression pattern of miRNAs in colorectal cancer make them viable disease determinants as well as potential therapeutic targets. Through this review, we will summarize the importance of miRNAs in the etiology and progression of colorectal cancer. Specifically, we will explore the key role played by these RNA molecules as likely therapeutic avenues and the strategies presently available to target them. Finally, we will investigate the role of miRNAs as potential non-invasive diagnostic and prognostic biomarkers in colorectal cancer.

Analysis of A 6-Mirna Signature in Serum from Colorectal Cancer Screening Participants as Non-Invasive Biomarkers for Advanced Adenoma and Colorectal Cancer Detection

Early detection of colorectal cancer (CRC) and its precancerous lesion, advanced adenomas (AA), is critical to improve CRC incidence and prognosis. Circulating microRNAs (miRNAs or miR) are promising non-invasive biomarkers for cancer detection. Our previous results showed that a plasma 6-miRNA signature (miR-15b-5p, miR-18a-5p, miR-29a-3p, miR-335-5p, miR-19a-3p and miR-19b-3p) could distinguish between CRC or AA and healthy individuals (controls). However, its diagnostic performance in serum is unknown. In this exploratory study we aim to evaluate the diagnostic performance of the 6-miRNA signature in serum samples in a cohort of individuals participating in Barcelona's CRC Screening Programme. We prospectively collected serums from 264 faecal immunochemical test (FIT)-positive participants and total RNA was extracted. Finally, 213 individuals (CRC, 59, AA, 74, controls, 80) were included. MiRNA expression was quantified by real-time RT-qPCR and data analysis was performed by logistic regression. Faecal hemoglobin concentration (f(Hb)) from FIT of the same individuals was also considered. As previously described in plasma, serum from patients with AA or CRC presented significant differences in the 6-miRNA signature compared to controls. Moreover, when combined with f(Hb), the final signature showed high discriminative capacity to distinguish CRC from controls (area under the curve (AUC) = 0.88), and even AA (AUC = 0.81) that otherwise are poorly detected if we only consider f(Hb) (AUC = 0.64). Addition of the serum 6-miRNA signature to quantitative f(Hb) show high accuracy to detect patients with advanced colorectal neoplasia in average-risk individuals. A combination of these two non-invasive methods could be a good strategy to improve diagnostic performances of current CRC screening programmes.

Cluster miRNAs and cancer: Diagnostic, prognostic and therapeutic opportunities

MiRNAs are class of noncoding RNA important for gene expression regulation in many plants, animals and viruses. MiRNA clusters contain a set of two or more miRNA encoding genes, transcribed together as polycistronic miRNAs. Currently, there are approximately 159 miRNA clusters reported in the human genome consisting of miRNAs ranging from two or more miRNA genes. A large proportion of clustered miRNAs resides in and around the fragile sites or cancer associated genomic hotspots and plays an important role in carcinogenesis. Altered expression of miRNA cluster can be pro-tumorigenic or anti-tumorigenic and can be targeted for clinical management of cancer. Over the past few years, manipulation of miRNA clusters expression is attempted for experimental purpose as well as for diagnostic, prognostic and therapeutic applications in cancer. Re-expression of miRNAs by epigenetic therapy, genome editing such as clustered regulatory interspaced short palindromic repeats (CRISPR) and miRNA mowers showed promising results in cancer therapy. In this review, we focused on the potential of miRNA clusters as a biomarker for diagnosis, prognosis, targeted therapy as well as strategies for modulating their expression in a therapeutic context. This article is categorized under: Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs RNA Processing > Processing of Small RNAs RNA in Disease and Development > RNA in Disease Regulatory RNAs/RNAi/Riboswitches > Biogenesis of Effector Small RNAs.

The landscape of genomic copy number alterations in colorectal cancer and their consequences on gene expression levels and disease outcome

Aneuploidy, the unbalanced state of the chromosome content, represents a hallmark of most solid tumors, including colorectal cancer. Such aneuploidies result in tumor specific genomic imbalances, which emerge in premalignant precursor lesions. Moreover, increasing levels of chromosomal instability have been observed in adenocarcinomas and are maintained in distant metastases. A number of studies have systematically integrated copy number alterations with gene expression changes in primary carcinomas, cell lines, and experimental models of aneuploidy. In fact, chromosomal aneuploidies target a number of genes conferring a selective advantage for the metabolism of the cancer cell. Copy number alterations not only have a positive correlation with expression changes of the majority of genes on the altered genomic segment, but also have effects on the transcriptional levels of genes genome-wide. Finally, copy number alterations have been associated with disease outcome; nevertheless, the translational applicability in clinical practice requires further studies. Here, we (i) review the spectrum of genetic alterations that lead to colorectal cancer, (ii) describe the most frequent copy number alterations at different stages of colorectal carcinogenesis, (iii) exemplify their positive correlation with gene expression levels, and (iv) discuss copy number alterations that are potentially involved in disease outcome of individual patients.

MicroRNA targeting by quercetin in cancer treatment and chemoprotection

A growing number of evidences from clinical and preclinical studies have shown that dysregulation of microRNA (miRNA) function contributes to the progression of cancer and thus miRNA can be an effective target in therapy. Dietary phytochemicals, such as quercetin, are natural products that have potential anti-cancer properties due to their proven antioxidant, anti-inflammatory, and anti-proliferative effects. Available experimental studies indicate that quercetin could modulate multiple cancer-relevant miRNAs including let-7, miR-21, miR-146a and miR-155, thereby inhibiting cancer initiation and development. This paper reviews the data supporting the use of quercetin for miRNA-mediated chemopreventive and therapeutic strategies in various cancers, with the aim to comprehensively understand its health-promoting benefits and pharmacological potential. Integration of technology platforms for miRNAs biomarker and drug discovery is also presented.

Oncogenic Biogenesis of pri-miR-17∼92 Reveals Hierarchy and Competition among Polycistronic MicroRNAs

The microRNAs encoded by the miR-17∼92 polycistron are commonly overexpressed in cancer and orchestrate a wide range of oncogenic functions. Here, we identify a mechanism for miR-17∼92 oncogenic function through the disruption of endogenous microRNA (miRNA) processing. We show that, upon oncogenic overexpression of the miR-17∼92 primary transcript (pri-miR-17∼92), the microprocessor complex remains associated with partially processed intermediates that aberrantly accumulate. These intermediates reflect a series of hierarchical and conserved steps in the early processing of the pri-miR-17∼92 transcript. Encumbrance of the microprocessor by miR-17∼92 intermediates leads to the broad but selective downregulation of co-expressed polycistronic miRNAs, including miRNAs derived from tumor-suppressive miR-34b/c and from the Dlk1-Dio3 polycistrons. We propose that the identified steps of polycistronic miR-17∼92 biogenesis contribute to the oncogenic re-wiring of gene regulation networks. Our results reveal previously unappreciated functional paradigms for polycistronic miRNAs in cancer.

Circulating biomarkers for early detection and clinical management of colorectal cancer

New non-invasive approaches that can complement and improve on current strategies for colorectal cancer (CRC) screening and management are urgently needed. A growing number of publications have documented that components of tumors, which are shed into the circulation, can be detected in the form of liquid biopsies and can be used to detect CRC at early stages, to predict response to certain therapies and to detect CRC recurrence in a minimally invasive way. The analysis of circulating tumor DNA (ctDNA), tumor-derived cells (CTC, circulating tumor cells) or circulating microRNA (miRNA) in blood and other body fluids, have a great potential to improve different aspects of CRC management. The challenge now is to find which types of components, biofluids and detection methods would be the most suitable to be applied in the different steps of CRC detection and treatment. This chapter will provide an up to date review on ctDNA, CTCs and circulating miRNAs as new biomarkers for CRC, either for clinical management or early detection, highlighting their advantages and limitations.

The diagnostic efficacy of circulating miRNAs in monitoring the early development of colitis-induced colorectal cancer

Early detection of colorectal cancer and monitoring the progress in colon carcinogenesis stages is essential to reduce mortality. Therefore, there is continuous search for noninvasive biomarkers with high stability and good sensitivity and specificity. miRNAs have attracted attention as promising biomarkers as they are stably expressed in circulation. The aim of our study is to evaluate the aberrant expression of circulating miRNAs during the stepwise progress of colitis-associated colon cancer. This was accomplished through assessing the expression levels of five miRNAs (miR-141, miR-15b, miR-17-3p, miR-21, and miR-29a) in serum and their corresponding tissue samples through the different cycles of colorectal carcinogenesis cascade using the azoxymethane/dextran sulfate sodium murine model. We also compared the diagnostic performance of these selected miRNAs with the conventional tumor biomarkers CEA and CA 19-9. The results of our study revealed that the expression levels of those miRNAs were dynamically changing in accordance with the tumor development state. Moreover, their aberrant expression in serum was statistically correlated with that in tissue. Our data also revealed that serum miR-15b, miR-21, and miR-29a showed the best performance in terms of diagnostic power. Our findings highlight the efficiency of these circulating miRNAs not only for early diagnostics purposes, but also for monitoring progress in the colorectal carcinogenesis process, and therefore encouraging integrating these noninvasive biomarkers into the clinical diagnostic settings beside the traditional diagnostic markers for accurate screening of the early progress of colon carcinogenesis.

High-Amylose Maize, Potato, and Butyrylated Starch Modulate Large Intestinal Fermentation, Microbial Composition, and Oncogenic miRNA Expression in Rats Fed A High-Protein Meat Diet

High red meat intake is associated with the risk of colorectal cancer (CRC), whereas dietary fibers, such as resistant starch (RS) seemed to protect against CRC. The aim of this study was to determine whether high-amylose potato starch (HAPS), high-amylose maize starch (HAMS), and butyrylated high-amylose maize starch (HAMSB)—produced by an organocatalytic route—could oppose the negative effects of a high-protein meat diet (HPM), in terms of fermentation pattern, cecal microbial composition, and colonic biomarkers of CRC. Rats were fed a HPM diet or an HPM diet where 10% of the maize starch was substituted with either HAPS, HAMS, or HAMSB, for 4 weeks. Feces, cecum digesta, and colonic tissue were obtained for biochemical, microbial, gene expression (oncogenic microRNA), and immuno-histochemical (O⁶-methyl-2-deoxyguanosine (O⁶MeG) adduct) analysis. The HAMS and HAMSB diets shifted the fecal fermentation pattern from protein towards carbohydrate metabolism. The HAMSB diet also substantially increased fecal butyrate concentration and the pool, compared with the other diets. All three RS treatments altered the cecal microbial composition in a diet specific manner. HAPS and HAMSB showed CRC preventive effects, based on the reduced colonic oncogenic miR17-92 cluster miRNA expression, but there was no significant diet-induced differences in the colonic O⁶MeG adduct levels. Overall, HAMSB consumption showed the most potential for limiting the negative effects of a high-meat diet.

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.

Association between polymorphisms of MIR17HG and risk of colorectal cancer in the Chinese Han population

Background

Colorectal cancer is the third most common cancer worldwide. Recently, an increasing number of evidences suggest that genetic susceptibility plays an important role in the occurrence of colorectal cancer. This study aimed to better understand the influence of MIR17HG polymorphisms on colorectal cancer susceptibility in the Chinese Han population.

Methods

We recruited 514 patients with colorectal cancer and 510 healthy controls to investigate the association between polymorphisms of MIR17HG and risk of colorectal cancer in the Chinese Han population. Genotyping was performed with the Agena MassARRAY platform. We used the χ² test to compare the distributions of single nucleotide polymorphisms (SNPs) allele and genotypes frequencies between cases and controls. Odds ratios and 95% confidence intervals were calculated by logistic regression analysis to evaluate the association under genetic models. Linkage disequilibrium between the five SNPs was assessed using the Haploview software.

Results

Overall analysis found that rs7336610 and rs1428 and haplotype CTAGA were significantly associated with increased risk of colorectal cancer. However, we found rs7318578 was associated with a decreased risk of colorectal cancer in the dominant model. Stratification analysis showed that rs7336610, rs7318578, and rs1428 were also associated with rectal cancer risk. Gender stratification analysis found that rs7336610, rs7318578, rs17735387, and rs1428 were significantly associated with colorectal cancer risk in males.

Conclusion

In conclusion, this study indicated that the polymorphisms of MIR17HG were associated with colorectal cancer risk. Therefore, our findings may provide new insights into the development of colorectal cancer. Further association and functional studies are of great importance to confirm these results and to define the potential biological mechanism of colorectal cancer.

Host⁻MicroRNA⁻Microbiota Interactions in Colorectal Cancer

Changes in gut microbiota composition have consistently been observed in patients with colorectal cancer (CRC). Yet, it is not entirely clear how the gut microbiota interacts with tumor cells. We know that tumor cells undergo a drastic change in energy metabolism, mediated by microRNAs (miRNAs), and that tumor-derived miRNAs affect the stromal and immune cell fractions of the tumor microenvironment. Recent studies suggest that host intestinal miRNAs can also affect the growth and composition of the gut microbiota. Our previous CRC studies showed a high-level of interconnectedness between host miRNAs and their microbiota. Considering all the evidence to date, we postulate that the altered nutrient composition and miRNA expression in the CRC microenvironment selectively exerts pressure on the surrounding microbiota, leading to alterations in its composition. In this review article, we present our current understanding of the role of miRNAs in mediating host–microbiota interactions in CRC.

MYC Oncogene Contributions to Release of Cell Cycle Brakes

Promotion of the cell cycle is a major oncogenic mechanism of the oncogene c-MYC (MYC). MYC promotes the cell cycle by not only activating or inducing cyclins and CDKs but also through the downregulation or the impairment of the activity of a set of proteins that act as cell-cycle brakes. This review is focused on the role of MYC as a cell-cycle brake releaser i.e., how MYC stimulates the cell cycle mainly through the functional inactivation of cell cycle inhibitors. MYC antagonizes the activities and/or the expression levels of p15, ARF, p21, and p27. The mechanism involved differs for each protein. p15 (encoded by CDKN2B) and p21 (CDKN1A) are repressed by MYC at the transcriptional level. In contrast, MYC activates ARF, which contributes to the apoptosis induced by high MYC levels. At least in some cells types, MYC inhibits the transcription of the p27 gene (CDKN1B) but also enhances p27's degradation through the upregulation of components of ubiquitin ligases complexes. The effect of MYC on cell-cycle brakes also opens the possibility of antitumoral therapies based on synthetic lethal interactions involving MYC and CDKs, for which a series of inhibitors are being developed and tested in clinical trials.

Impact of the gut microbiome on the genome and epigenome of colon epithelial cells: contributions to colorectal cancer development

In recent years, the number of studies investigating the impact of the gut microbiome in colorectal cancer (CRC) has risen sharply. As a result, we now know that various microbes (and microbial communities) are found more frequently in the stool and mucosa of individuals with CRC than healthy controls, including in the primary tumors themselves, and even in distant metastases. We also know that these microbes induce tumors in various mouse models, but we know little about how they impact colon epithelial cells (CECs) directly, or about how these interactions might lead to modifications at the genetic and epigenetic levels that trigger and propagate tumor growth. Rates of CRC are increasing in younger individuals, and CRC remains the second most frequent cause of cancer-related deaths globally. Hence, a more in-depth understanding of the role that gut microbes play in CRC is needed. Here, we review recent advances in understanding the impact of gut microbes on the genome and epigenome of CECs, as it relates to CRC. Overall, numerous studies in the past few years have definitively shown that gut microbes exert distinct impacts on DNA damage, DNA methylation, chromatin structure and non-coding RNA expression in CECs. Some of the genes and pathways that are altered by gut microbes relate to CRC development, particularly those involved in cell proliferation and WNT signaling. We need to implement more standardized analysis strategies, collate data from multiple studies, and utilize CRC mouse models to better assess these effects, understand their functional relevance, and leverage this information to improve patient care.

Overexpression of microRNA‑101 causes anti‑tumor effects by targeting CREB1 in colon cancer

Accumulating evidence has demonstrated that aberrantly expressed microRNAs (miRNAs) are involved in the initiation and progression of numerous types of human cancer. Although a number of miRNAs have been demonstrated to be associated with the diagnosis, progression and prognosis of colon cancer, the function of miRNA‑101 (miR‑101) in colon cancer remains unclear, and the molecular mechanisms underlying the effects of miR‑101 in colon cancer require further investigation. The present study investigated the role of miR‑101 in colon cancer, and the results suggested that miR‑101 expression levels were significantly decreased in colorectal carcinoma tissues and in three types of colorectal cancer cell lines. Furthermore, overexpression of miR‑101 inhibited cell proliferation and migration in HT29 cells. The transcription factor cAMP responsive element binding protein 1 (CREB1) was identified to be a direct target of miR‑101 using a luciferase reporter assay, reverse transcription‑quantitative polymerase chain reaction analysis and western blot assay. miR‑101 overexpression in tumor xenografts in vivo decreased the expression levels of proliferating cell nuclear antigen and CREB1, and suppressed tumor growth. The present results suggested that miR‑101 may serve a role in colon cancer by directly targeting CREB1. Collectively, the present study may contribute to the development of improved diagnosis and prognostics for colon cancer.

Strategies for targeting energy metabolism in Kirsten rat sarcoma viral oncogene homolog -mutant colorectal cancer

Alterations in cellular energy metabolism play critical roles in colorectal cancer (CRC). These alterations, which correlate to KRAS mutations, have been identified as energy metabolism signatures. This review summarizes the relationship between colorectal tumors associated with mutated KRAS and energy metabolism, especially for the deregulated energy metabolism that affects tumor cell proliferation, invasion, and migration. Furthermore, this review will concentrate on the role of metabolic genes, factors and signaling pathways, which are coupled with the primary energy source connected with the KRAS mutation that induces metabolic alterations. Strategies for targeting energy metabolism in mutated KRAS CRC are also introduced. In conclusion, deregulated energy metabolism has a close relationship with KRAS mutations in colorectal tumors. Therefore, selective inhibitors, agents against metabolic targets or KRAS signaling, may be clinically useful for colorectal tumor treatment through a patient-personalized approach.

MiR-222-3p in Platelets Serves as a Distinguishing Marker for Early Recognition of Kawasaki Disease

Kawasaki disease (KD) is an acute vasculitis, which leads to 20% of sufferers developing coronary artery aneurysm in children if not appropriately treated. Therefore, the early diagnosis of KD is essential for alleviating the risk of developing heart disease. MicroRNAs (miRNAs) are a large class of small non-coding RNAs which post-transcriptionally regulate gene expression and have been shown to play critical roles in numerous biological processes and diseases. In this study, we used high-throughput miRNA sequencing and found dozens of miRNAs are highly expressed in platelets. By comparing the miRNA expression profile of platelets of acute KD patients and other febrile patients, miR-222-3p is validated to be significantly upregulated in platelets of acute KD patients. Furthermore, KEGG pathway analysis shows that targets of miR-222-3p are enriched in immune-related signaling pathways. Our study uncovers the potential of miR-222-3p in platelets as biomarker for early diagnosis of Kawasaki disease.

IFNγ-Induced IFIT5 Promotes Epithelial-to-Mesenchymal Transition in Prostate Cancer via miRNA Processing

IFNγ, a potent cytokine known to modulate tumor immunity and tumoricidal effects, is highly elevated in patients with prostate cancer after radiation. In this study, we demonstrate that IFNγ can induce epithelial-to-mesenchymal transition (EMT) in prostate cancer cells via the JAK-STAT signaling pathway, leading to the transcription of IFN-stimulated genes (ISG) such as IFN-induced tetratricopeptide repeat 5 (IFIT5). We unveil a new function of IFIT5 complex in degrading precursor miRNAs (pre-miRNA) that includes pre-miR-363 from the miR-106a-363 cluster as well as pre-miR-101 and pre-miR-128, who share a similar 5'-end structure with pre-miR-363. These suppressive miRNAs exerted a similar function by targeting EMT transcription factors in prostate cancer cells. Depletion of IFIT5 decreased IFNγ-induced cell invasiveness in vitro and lung metastasis in vivo. IFIT5 was highly elevated in high-grade prostate cancer and its expression inversely correlated with these suppressive miRNAs. Altogether, this study unveils a prometastatic role of the IFNγ pathway via a new mechanism of action, which raises concerns about its clinical application.Significance: A unique IFIT5-XRN1 complex involved in the turnover of specific tumor suppressive microRNAs is the underlying mechanism of IFNγ-induced epithelial-to-mesenchymal transition in prostate cancer.See related commentary by Liu and Gao, p. 1032.

AngiomiRs: MicroRNAs driving angiogenesis in cancer (Review)

Angiogenesis is an important hallmark of cancer serving a key role in tumor growth and metastasis. Therefore, tumor angiogenesis has become an attractive target for development of novel drug therapies. An increased amount of anti‑angiogenic compounds is currently in preclinical and clinical development for personalized therapies. However, resistance to current angiogenesis inhibitors is emerging, indicating that there is a need to identify novel anti‑angiogenic agents. In the last decade, the field of microRNA biology has exploded revealing unsuspected functions in tumor angiogenesis. These small non‑coding RNAs, which have been dubbed as angiomiRs, may target regulatory molecules driving angiogenesis, such as cytokines, metalloproteinases and growth factors, including vascular endothelial growth factor, platelet‑derived growth factor, fibroblast growth factor, epidermal growth factor, hypoxia inducible factor‑1, as well as mitogen‑activated protein kinase, phosphoinositide 3‑kinase and transforming growth factor signaling pathways. The present review discusses the current progress towards understanding the functions of miRNAs in tumor angiogenesis regulation in diverse types of human cancer. Furthermore, the potential clinical application of angiomiRs towards anti‑angiogenic tumor therapy was explored.

Adherence to the World Cancer Research Fund/American Institute for Cancer Research cancer prevention recommendations and WNT-pathway-related markers of bowel cancer risk

Bowel cancer risk is strongly influenced by lifestyle factors including diet and physical activity. Several studies have investigated the effects of adherence to the World Cancer Research Fund (WCRF)/American Institute for Cancer Research (AICR) cancer prevention recommendations on outcomes such as all-cause and cancer-specific mortality, but the relationships with molecular mechanisms that underlie the effects on bowel cancer risk are unknown. This study aimed to investigate the relationships between adherence to the WCRF/AICR cancer prevention recommendations and wingless/integrated (WNT)-pathway-related markers of bowel cancer risk, including the expression of WNT pathway genes and regulatory microRNA (miRNA), secreted frizzled-related protein 1 (SFRP1) methylation and colonic crypt proliferative state in colorectal mucosal biopsies. Dietary and lifestyle data from seventy-five healthy participants recruited as part of the DISC Study were used. A scoring system was devised including seven of the cancer prevention recommendations and smoking status. The effects of total adherence score and scores for individual recommendations on the measured outcomes were assessed using Spearman's rank correlation analysis and unpaired t tests, respectively. Total adherence score correlated negatively with expression of Myc proto-oncogene (c-MYC) (P=0·039) and WNT11 (P=0·025), and high adherers had significantly reduced expression of cyclin D1 (CCND1) (P=0·042), WNT11 (P=0·012) and c-MYC (P=0·048). Expression of axis inhibition protein 2 (AXIN2), glycogen synthase kinase (GSK3β), catenin β1 (CTNNB1) and WNT11 and of the oncogenic miRNA miR-17 and colonic crypt kinetics correlated significantly with scores for individual recommendations, including body fatness, red meat intake, plant food intake and smoking status. The findings from this study provide evidence for positive effects of adherence to the WCRF/AICR cancer prevention recommendations on WNT-pathway-related markers of bowel cancer risk.