MicroRNA-451 is involved in the self-renewal, tumorigenicity, and chemoresistance of colorectal cancer stem cells

miRNA on the Battlefield of Cancer: Significance in Cancer Stem Cells, WNT Pathway, and Treatment

Carcinogenesis is a complex process characterized by intricate changes in organ histology, biochemistry, epigenetics, and genetics. Within this intricate landscape, cancer stem cells (CSCs) have emerged as distinct cell types possessing unique attributes that significantly contribute to the pathogenesis of cancer. The WNT signaling pathway plays a critical role in maintaining somatic stem cell pluripotency. However, in cancer, overexpression of WNT mediators enhances the activity of β-catenin, resulting in phenomena such as recurrence and unfavorable survival outcomes. Notably, CSCs exhibit heightened WNT signaling compared to bulk cancer cells, providing intriguing insights into their functional characteristics. MicroRNAs (miRNAs), as post-transcriptional gene expression regulators, modulate various physiological processes in numerous diseases including cancer. Upregulation or downregulation of miRNAs can affect the production of pro-oncogenic or anti-oncogenic proteins, influencing cellular processes that maintain tissue homeostasis and promote either apoptosis or differentiation, even in cancer cells. In order to understand the dysregulation of miRNAs, it is essential to examine miRNA biogenesis and any possible alterations at each step. The potential of a miRNA as a biomarker in prognosis, diagnosis, and detection is being assessed using technologies such as next-generation sequencing. Extensive research has explored miRNA expression profiles in cancer, leading to their utilization as diagnostic tools and the development of personalized and targeted cancer therapies. This review delves into the role of miRNAs in carcinogenesis in relation to the WNT signaling pathway along with their potential as druggable compounds.

A concise review on miRNAs as regulators of colon cancer stem cells and associated signalling pathways

Despite recent therapy advances and a better understanding of colon cancer biology, it remains one of the major causes of death. The cancer stem cells, associated with the progression, metastasis, and recurrence of colon cancer, play a major role in promoting the development of tumour and are found to be chemo resistant. The stroma of the tumour, which makes up the bulk of the tumour mass, is composed of the tumour microenvironment. With the advent of theranostic and the development of personalised medicine, miRNAs are becoming increasingly important in the context of colon malignancies. A holistic understanding of the regulatory roles of miRNAs in cancer cells and cancer stem cells will allow us to design effective strategies to regulate miRNAs, which could lead to improved clinical translation and creating a potent colon cancer treatment strategy. In this review paper, we briefly discuss the history of miRNA as well as the mechanisms of miRNA and cancer stem cells that contribute to the tumour growth, apoptosis, and advancement of colon cancer. The usefulness of miRNA in colorectal cancer theranostic is further concisely reviewed. We conclude by holding a stance in addressing the prospects and possibilities for miRNA by the disclosure of recent theranostic approaches aimed at eradicating cancer stem cells and enhancing overall cancer treatment outcomes.

Double-edged sword role of miRNA-633 and miRNA-181 in human cancers

Understanding the function and mode of operation of microRNAs (miRNAs) in cancer is of growing interest. The short non-coding RNAs known as miRNAs, which target mRNA in multicellular organisms, are described as controlling essential cellular processes. The miR-181 family and miR-633 are well-known miRNAs that play a key role in the development and metastasis of tumor cells. They may facilitate either tumor-suppressive or oncogenic function in malignant cells, according to mounting evidence. Metastatic cells that are closely linked to cancer cell migration, invasion, and angiogenesis can be identified by abnormal levels of miR-181 and miR-633. Numerous studies have demonstrated their capacity to control drug resistance, cell growth, apoptosis, and the epithelial-mesenchymal transition (EMT) and metastasis process. Interestingly, the levels of miR-181 and miR-633 and their potential target genes in the basic cellular process can vary depending on the type of cancer cells and their gene expression profile. Such miRNAs' interactions with other non-coding RNAs such as long non-coding RNAs and circular RNAs can influence tumor behaviors. Herein, we concentrated on the multifaceted roles of miR-181 and miR-633 and potential targets in human tumorigenesis, ranging from cell growth and metastasis to drug resistance.

Recent advances microRNAs and metabolic reprogramming in colorectal cancer research

Colorectal cancer (CRC) is a cancer with the highest incidence and mortality. Alteration of gene expression is the main pathophysiological mechanism of CRC, which results in disturbed signaling pathways and cellular metabolic processes. MicroRNAs are involved in almost all pathophysiological processes and are correlative with colorectal cancer metabolism, proliferation, and chemotherapy resistance. Metabolic reprogramming, an important feature of cancer, is strongly correlative with the development and prognosis of cancers, including colorectal cancer. MicroRNAs can target enzymes involved in metabolic processes, thus playing a regulatory role in tumor metabolism. The disorder of the signaling pathway is another characteristic of tumor, which induces the occurrence and proliferation of tumors, and is closely correlative with the prognosis and chemotherapy resistance of tumor patients. MicroRNAs can target the components of the signaling pathways to regulate their transduction. Understanding the function of microRNAs in the occurrence and proliferation of CRC provides novel insights into the optimal treatment strategies, prognosis, and development of diagnosis in CRC. This article reviews the relationship between CRC and microRNA expression and hopes to provide new options for the diagnosis and treatment of CRC.

Potential Phytochemicals for Prevention of Familial Breast Cancer with BRCA Mutations

Breast cancer has remained a global challenge and the second leading cause of cancer mortality in women and family history. Hereditary factors are some of the major risk factors associated with breast cancer. Out of total breast cancer cases, 5-10% account only for familial breast cancer, and nearly 50% of all hereditary breast cancer are due to BRCA1/BRCA2 germline mutations. BRCA1/2 mutations play an important role not only in determining the clinical prognosis of breast cancer but also in the survival curves. Since this risk factor is known, a significant amount of the healthcare burden can be reduced by taking preventive measures among people with a known history of familial breast cancer. There is increasing evidence that phytochemicals of nutrients and supplements help in the prevention and cure of BRCA-related cancers by different mechanisms such as limiting DNA damage, altering estrogen metabolism, or upregulating expression of the normal BRCA allele, and ultimately enhancing DNA repair. This manuscript reviews different approaches used to identify potential phytochemicals to mitigate the risk of familial breast cancer with BRCA mutations. The findings of this review can be extended for the prevention and cure of any BRCAmutated cancer after proper experimental and clinical validation of the data.

Concise review: Cancer cell reprogramming and therapeutic implications

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The cancer stem cell (CSC) act as tumor initiating cells.

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Reprogramming technology can convert cells into CSCs.

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Metabolic reprogramming is critical for CSCs.

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MiRNA can mediate cancer cell reprogramming as emerging alternatives.

The cancer stem cell (CSC) hypothesis postulates that cancer originates from the malignant transformation of stem cells and is considered to apply to a variety of cancers. Additionally, cancer cells alter metabolic processes to sustain their characteristic uncontrolled growth and proliferation. Further, microRNAs (miRNAs) are found to be involved in acquisition of stem cell-like properties, regulation and reprogramming of cancer cells during cancer progression through its post-transcriptional-regulatory activity. In this concise review, we aim to integrate the current knowledge and recent advances to elucidate the mechanisms involved in the regulation of cell reprogramming and highlights the potential therapeutic implications for the future.

Combination of 7-O-geranylquercetin and microRNA-451 enhances antitumor effect of Adriamycin by reserving P-gp-mediated drug resistance in breast cancer

Although there are a lot of chemical drugs to treat breast cancer, increasing drug resistance of cancer cells has strongly hindered the effectiveness of chemotherapy. ATP-binding cassette transporters represented by P-glycoprotein (P-gp), multidrug resistance associated protein 1 (MRP1) and breast cancer resistance protein (BCRP) play an important role in drug resistance. This study aims to investigate the effect of 7-O-geranylquercetin (GQ) combining microRNA-451(miR-451) on reversing drug resistance of breast cancer and reveal the mechanism related to P-gp. Real-time RT-PCR and western blot assays showed that miR-326, miR-328, miR-451 and miR-155 inhibitor down-regulated the expression of genes MRP1, BCRP, MDR1 and the corresponding proteins MRP1, BCRP, P-gp, respectively. Cell counting kit-8 (CCK-8) assay indicated that these miRNAs reversed the resistance of MCF-7/ADR cells to Adriamycin (ADR), and miR-451 showed the greatest reversal effect. Combination of GQ and miR-451 enhanced the inhibitory effects of ADR on the proliferation and migration of MCF-7/ADR cells, and attenuated the expression of MDR1 and P-gp in MCF-7/ADR cells. A xenograft tumor model was used to show that GQ and miR-451 amplified the antitumor effect of ADR in nude mice, while western blot and immunohistochemical assays revealed the decreased expression of P-gp in tumor tissues. These results suggest that GQ and miR-451 have synergistic effect on reversing drug resistance through reducing the expression of MDR1 and P-gp in breast cancer MCF-7/ADR cells.

A Systematic Review of Clinical Validated and Potential miRNA Markers Related to the Efficacy of Fluoropyrimidine Drugs

Colorectal cancer (CRC) is becoming increasingly prevalent worldwide. Fluoropyrimidine drugs are the primary chemotherapy regimens in routine clinical practice of CRC. However, the survival rate of patients on fluoropyrimidine-based chemotherapy varies significantly among individuals. Biomarkers of fluoropyrimidine drugs'' efficacy are needed to implement personalized medicine. This review summarized fluoropyrimidine drug-related microRNA (miRNA) by affecting metabolic enzymes or showing the relevance of drug efficacy. We first outlined 42 miRNAs that may affect the metabolism of fluoropyrimidine drugs. Subsequently, we filtered another 41 miRNAs related to the efficacy of fluoropyrimidine drugs based on clinical trials. Bioinformatics analysis showed that most well-established miRNA biomarkers were significantly enriched in the cancer pathways instead of the fluoropyrimidine drug metabolism pathways. The result also suggests that the miRNAs screened from metastasis patients have a more critical role in cancer development than those from non-metastasis patients. There are five miRNAs shared between these two lists. The miR-21, miR-215, and miR-218 can suppress fluoropyrimidine drugs'' catabolism. The miR-326 and miR-328 can reduce the efflux of fluoropyrimidine drugs. These five miRNAs could jointly act by increasing intracellular levels of fluoropyrimidine drugs'' cytotoxic metabolites, leading to better chemotherapy responses. In conclusion, we demonstrated that the dynamic changes in the transcriptional regulation via miRNAs might play significant roles in the efficacy and toxicity of the fluoropyrimidine drug. The reported miRNA biomarkers would help evaluate the efficacy of fluoropyrimidine drug-based chemotherapy and improve the prognosis of colorectal cancer patients.

TA-MSCs, TA-MSCs-EVs, MIF: their crosstalk in immunosuppressive tumor microenvironment

As an important component of the immunosuppressive tumor microenvironment (TME), it has been established that mesenchymal stem cells (MSCs) promote the progression of tumor cells. MSCs can directly promote the proliferation, migration, and invasion of tumor cells via cytokines and chemokines, as well as promote tumor progression by regulating the functions of anti-tumor immune and immunosuppressive cells. MSCs-derived extracellular vesicles (MSCs-EVs) contain part of the plasma membrane and signaling factors from MSCs; therefore, they display similar effects on tumors in the immunosuppressive TME. The tumor-promoting role of macrophage migration inhibitory factor (MIF) in the immunosuppressive TME has also been revealed. Interestingly, MIF exerts similar effects to those of MSCs in the immunosuppressive TME. In this review, we summarized the main effects and related mechanisms of tumor-associated MSCs (TA-MSCs), TA-MSCs-EVs, and MIF on tumors, and described their relationships. On this basis, we hypothesized that TA-MSCs-EVs, the MIF axis, and TA-MSCs form a positive feedback loop with tumor cells, influencing the occurrence and development of tumors. The functions of these three factors in the TME may undergo dynamic changes with tumor growth and continuously affect tumor development. This provides a new idea for the targeted treatment of tumors with EVs carrying MIF inhibitors.

miRNAs as cornerstones in colorectal cancer pathogenesis and resistance to therapy: A spotlight on signaling pathways interplay - A review

Colorectal cancer (CRC) is the world's third most prevalent cancer and the main cause of cancer-related mortality. A lot of work has been put into improving CRC patients' clinical care, including the development of more effective methods and wide biomarkers variety for prognostic, and diagnostic purposes. MicroRNAs (miRNAs) regulate a variety of cellular processes and play a significant role in the CRC progression and spread via controlling their target gene expression by translation inhibition or mRNA degradation. Consequently, dysregulation and disruption in their function, miRNAs are linked to CRC malignant pathogenesis by controlling several cellular processes involved in the CRC. These cellular processes include increased proliferative and invasive capacity, cell cycle aberration, evasion of apoptosis, enhanced EMT, promotion of angiogenesis and metastasis, and decreased sensitivity to major treatments. The miRNAs control cellular processes in CRC via regulation of pathways such as Wnt/β-catenin signaling, PTEN/AKT/mTOR axis, KRAS, TGFb signaling, VEGFR, EGFR, and P53. Hence, the goal of this review was to review miRNA biogenesis and present an updated summary of oncogenic and tumor suppressor (TS) miRNAs and their potential implication in CRC pathogenesis and responses to chemotherapy and radiotherapy. We also summarise the biological importance and clinical applications of miRNAs in the CRC.

Diagnostic Potential of Exosomal microRNAs in Colorectal Cancer

Background: Despite the significance of colonoscopy for early diagnosis of colorectal adenocarcinoma (CRC), population-wide screening remains challenging, mainly because of low acceptance rates. Herein, exosomal (exo-miR) and free circulating microRNA (c-miR) may be used as liquid biopsies in CRC to identify individuals at risk. Direct comparison of both compartments has shown inconclusive results, which is why we directly compared a panel of 10 microRNAs in this entity. Methods: Exo-miR and c-miR levels were measured using real-time quantitative PCR after isolation from serum specimens in a cohort of 69 patients. Furthermore, results were compared to established tumor markers CEA and CA 19-9. Results: Direct comparison of exo- and c-miR biopsy results showed significantly higher microRNA levels in the exosomal compartment (p < 0.001). Exo-Let7, exo-miR-16 and exo-miR-23 significantly differed between CRC and healthy controls (all p < 0.05), while no c-miR showed this potential. Sensitivity and specificity can be further enhanced using combinations of multiple exosomal miRNAs. Conclusions: Exosomal microRNA should be considered as a promising biomarker in CRC for future studies. Nonetheless, results may show interference with common comorbidities, which must be taken into account in future studies.

Perspectives of using microRNA-loaded nanocarriers for epigenetic reprogramming of drug resistant colorectal cancers

Epigenetic regulation by microRNAs (miRs) demonstrated a promising therapeutic potential of these molecules to regulate genetic activity in different cancers, including colorectal cancers (CRCs). The RNA-based therapy does not change genetic codes in tumor cells but can silence oncogenes and/or reactivate inhibited tumor suppressor genes. In many cancers, specific miRs were shown to promote or stop tumor progression. Among confirmed and powerful epigenetic regulators of colon carcinogenesis and development of resistance are onco-miRs, which include let-7, miR-21, miR-22, miR-23a, miR-27a, miR-34, miR-92, miR-96, miR-125b, miR-135b, miR-182, miR-200c, miR-203, miR-221, miR-421, miR-451, and others. Moreover, various tumor-suppressor miRs (miR-15b-5b, miR-18a, miR-20b, miR-22, miR-96, miR-139-5p, miR-145, miR-149, miR-197, miR-199b, miR-203, miR-214, miR-218, miR-320, miR-375-3p, miR-409-3p, miR-450b-5p, miR-494, miR-577, miR-874, and others) were found silenced in drug-resistant CRCs. Re-expression of tumor suppressor miR is complicated by the chemical nature of miRs that are not long-lasting compounds and require protection from the enzymatic degradation. Several recent studies explored application of miRs using nanocarrier complexes. This study critically describes the most successfully tested nanoparticle complexes used for intracellular delivery of nuclear acids and miRs, including micelles, liposomes, inorganic and polymeric NPs, dendrimers, and aptamers. Nanocarriers shield incorporated miRs and improve the agent stability in circulation. Attachment of antibodies and/or specific peptide or ligands facilitates cell-targeted miR delivery. Addressing in vivo challenges, a broad spectrum of non-toxic materials has been tested and indicated reliable advantages of lipid-based (lipoplexes) and polymer-based liposomes. Recent cutting-edge developments indicated that lipid-based complexes with multiple cargo, including several miRs, are the most effective approach to eradicate drug-resistant tumors. Focusing on CRC-specific miRs, this review provides a guidance and insights towards the most promising direction to achieve dramatic reduction in tumor growth and metastasis using miR-nanocarrier complexes.

MicroRNA as a Potential Therapeutic Molecule in Cancer

Small noncoding RNAs, as post-translational regulators of many target genes, are not only markers of neoplastic disease initiation and progression, but also markers of response to anticancer therapy. Hundreds of miRNAs have been identified as biomarkers of drug resistance, and many have demonstrated the potential to sensitize cancer cells to therapy. Their properties of modulating the response of cells to therapy have made them a promising target for overcoming drug resistance. Several methods have been developed for the delivery of miRNAs to cancer cells, including introducing synthetic miRNA mimics, DNA plasmids containing miRNAs, and small molecules that epigenetically alter endogenous miRNA expression. The results of studies in animal models and preclinical studies for solid cancers and hematological malignancies have confirmed the effectiveness of treatment protocols using microRNA. Nevertheless, the use of miRNAs in anticancer therapy is not without limitations, including the development of a stable nanoconstruct, delivery method choices, and biodistribution. The aim of this review was to summarize the role of miRNAs in cancer treatment and to present new therapeutic concepts for these molecules. Supporting anticancer therapy with microRNA molecules has been verified in numerous clinical trials, which shows great potential in the treatment of cancer.

MicroRNAs and drug resistance in colorectal cancer with special focus on 5-fluorouracil

Colorectal cancer is globally one of the most common cancers in all age groups. The current chemotherapy combinations for colorectal cancer treatment include 5-fluorouracil-based regimens; however, drug resistance remains one of the main reasons for chemotherapy failure and disease recurrence. Many studies have determined colorectal cancer chemoresistance mechanisms such as drug efflux, cell cycle arrest, DNA damage repair, apoptosis, autophagy, vital enzymes, epigenetic, epithelial-mesenchymal transition, stem cells, and immune system suppression. Several microRNAs affect drug resistance by regulating the drug resistance-related target genes in colorectal cancer. These drug resistance-related miRNAs may be used as promising biomarkers for predicting drug response or as potential therapeutic targets for treating patients with colorectal cancer. This work reviews and discuss the role of selected microRNAs in 5-fluorouracil resistance and their molecular mechanisms in colorectal cancer.

LncRNAs, the Molecules Involved in Communications With Colorectal Cancer Stem Cells

Colorectal cancer stem cells (CRCSCs) can actively self-renew, as well as having multidirectional differentiation and tumor regeneration abilities. Because the high functional activities of CRCSCs are associated with low cure rates in patients with colorectal cancer, efforts have sought to determine the function and regulatory mechanisms of CRCSCs. To date, however, the potential regulatory mechanisms of CRCSCs remain incompletely understood. Many non-coding genes are involved in tumor invasion and spread through their regulation of CRCSCs, with long non-coding RNAs (lncRNAs) being important non-coding RNAs. LncRNAs may be involved in the colorectal cancer development and drug resistance through their regulation of CRCSCs. This review systematically evaluates the latest research on the ability of lncRNAs to regulate CRCSC signaling pathways and the involvement of these lncRNAs in colorectal cancer promotion and suppression. The regulatory network of lncRNAs in the CRCSC signaling pathway has been determined. Further analysis of the potential clinical applications of lncRNAs as novel clinical diagnostic and prognostic biomarkers and therapeutic targets for colorectal cancer may provide new ideas and protocols for the prevention and treatment of colorectal cancer.

MicroRNA and Alternative mRNA Splicing Events in Cancer Drug Response/Resistance: Potent Therapeutic Targets

Cancer is a multifaceted disease that involves several molecular mechanisms including changes in gene expression. Two important processes altered in cancer that lead to changes in gene expression include altered microRNA (miRNA) expression and aberrant splicing events. MiRNAs are short non-coding RNAs that play a central role in regulating RNA silencing and gene expression. Alternative splicing increases the diversity of the proteome by producing several different spliced mRNAs from a single gene for translation. MiRNA expression and alternative splicing events are rigorously regulated processes. Dysregulation of miRNA and splicing events promote carcinogenesis and drug resistance in cancers including breast, cervical, prostate, colorectal, ovarian and leukemia. Alternative splicing may change the target mRNA 3'UTR binding site. This alteration can affect the produced protein and may ultimately affect the drug affinity of target proteins, eventually leading to drug resistance. Drug resistance can be caused by intrinsic and extrinsic factors. The interplay between miRNA and alternative splicing is largely due to splicing resulting in altered 3'UTR targeted binding of miRNAs. This can result in the altered targeting of these isoforms and altered drug targets and drug resistance. Furthermore, the increasing prevalence of cancer drug resistance poses a substantial challenge in the management of the disease. Henceforth, molecular alterations have become highly attractive drug targets to reverse the aberrant effects of miRNAs and splicing events that promote malignancy and drug resistance. While the miRNA-mRNA splicing interplay in cancer drug resistance remains largely to be elucidated, this review focuses on miRNA and alternative mRNA splicing (AS) events in breast, cervical, prostate, colorectal and ovarian cancer, as well as leukemia, and the role these events play in drug resistance. MiRNA induced cancer drug resistance; alternative mRNA splicing (AS) in cancer drug resistance; the interplay between AS and miRNA in chemoresistance will be discussed. Despite this great potential, the interplay between aberrant splicing events and miRNA is understudied but holds great potential in deciphering miRNA-mediated drug resistance.

Global identification of circular RNAs in imatinib (IM) resistance of chronic myeloid leukemia (CML) by modulating signaling pathways of circ_0080145/miR-203/ABL1 and circ 0051886/miR-637/ABL1

Imatinib (IM), targeting of BCR-ABL1 tyrosine kinase, is currently one of the first-line choices in the treatment of chronic myeloid leukemia (CML). This study aims to explore the molecular mechanisms underlying IM resistance in CML treatment. 108 CML patients were recruited and grouped according to their sensitivity to IM as the responder group (N = 66) and the non-responder group (N = 42). Real-time quantitative PCR (RT-qPCR) was performed to evaluate the expression of candidate circular RNAs (circRNAs), microRNA (miRNAs) and messenger RNA (mRNAs). No significant difference was noted regarding demographic and clinicopathological characteristics between the responder group and the non-responder group. The expression of circ_0080145, circ_0051886 and ABL1 mRNA was significantly increased, while the expression of miR-203 and miR-637 was decreased in the non-responder group as compared with the responders. By using in-silicon analysis, it was predicted that circ_0080145 and circ_0051886 targeted miR-203 and miR-637 respectively, and ABL1 was found to be shared direct target gene of miR-203 and miR-637. Ectopic over-expression of circ_0080145 and circ_0051886 respectively reduced the expression of miR-203 and miR-637. The expression of ABL1 mRNA/protein was most upregulated in culture cells co-transfected with circ_0080145 and circ_0051886 as compared with those cells individually transfected. This study established the signaling pathways of circ_0080145/miR-203/ABL1 and circ 0051886/miR-637/ABL1. The deregulation of circ_0080145 and circ_0051886 is, at least partially, responsible for the development of IM chemoresistance in CML by regulating expression of ABL1 via modulating expression of miR-203 and miR-637.

An Overview on the Role of miR-451 in Lung Cancer: Diagnosis, Therapy, and Prognosis

MicroRNAs (miRNAs) are highly conserved non-coding RNAs involved in many physiological processes such as cell proliferation, inhibition, development of apoptosis, differentiation, suppresses tumorigenicity, and regulating cell growth. The description of the alterations of miRNA expression patterns in cancers will be helpful to recognize biomarkers for early detection and possible therapeutic intervention in the treatment of cancers. Recent studies have shown that miR-451 is broadly dysregulated in lung cancer and is a crucial agent in lung tumor progression. This review summarizes recent advances of the potential role of miR-451 in lung cancer diagnosis, prognosis, and treatment and provides an insight into the potential use of miR-451 for the development of advanced therapeutic methods in lung cancer.

Drug resistance in colorectal cancer: An epigenetic overview

Colorectal cancer (CRC) is a leading cause of cancer-related deaths worldwide. Despite significant progress that has been made in therapies against CRC over the past decades, drug resistance is still a major limitation in CRC treatment. Numerous investigations have unequivocally shown that epigenetic regulation plays an important role in CRC drug resistance because of the high rate of epigenetic alterations in multiple genes during cancer development or drug treatment. Furthermore, the reversibility of epigenetic alterations provides novel therapeutic strategies to overcome drug resistance using small molecules, which can target non-coding RNAs or reverse histone modification and DNA methylation. In this review, we discuss epigenetic regulation in CRC drug resistance and the possible role of preventing or reversing CRC drug resistance using epigenetic therapy in CRC treatment.

MiRNA-Wnt signaling regulatory network in colorectal cancer

Colorectal cancer (CRC) is one of the common malignancies worldwide and the Wnt signaling pathway is recognized as the main disrupted pathway in this malignancy. MicroRNAs (miRNAs) are recognized to contribute to the pathogenesis of CRC by triggering or impeding the Wnt signaling pathway. In addition, transcriptional regulation of miRNAs by canonical Wnt signaling also participates in CRC cell progression. In this review, we present comprehensive literature of the existing data on the interaction of miRNAs and Wnt signaling that could be useful in future studies in the field of CRC management.

The Inflammatory Profile of the Tumor Microenvironment, Orchestrated by Cyclooxygenase-2, Promotes Epithelial-Mesenchymal Transition

The tumor microenvironment (TME) corresponds to a complex and dynamic interconnection between the extracellular matrix and malignant cells and their surrounding stroma composed of immune and mesenchymal cells. The TME has constant cellular communication through cytokines that sustain an inflammatory profile, which favors tumor progression, angiogenesis, cell invasion, and metastasis. Although the epithelial-mesenchymal transition (EMT) represents a relevant metastasis-initiating event that promotes an invasive phenotype in malignant epithelial cells, its relationship with the inflammatory profile of the TME is poorly understood. Previous evidence strongly suggests that cyclooxygenase-2 (COX-2) overexpression, a pro-inflammatory enzyme related to chronic unresolved inflammation, is associated with common EMT-signaling pathways. This review article summarizes how COX-2 overexpression, within the context of the TME, orchestrates the EMT process and promotes initial metastatic-related events.

Circular RNA circ‑CCT3 promotes hepatocellular carcinoma progression by regulating the miR‑1287‑5p/TEAD1/PTCH1/LOX axis

Hepatocellular carcinoma (HCC) is characterized by a poor prognosis because of its insensitivity to radiation and chemotherapy. Recently, circular RNAs (circRNAs) have been found to serve important roles in hepatocellular carcinogenesis. circ-CCT3, a novel circRNA, was screened from the differential tissue expression results of a circRNA microarray. Relative expression levels of circ-CCT3 in specimens and cell lines were evaluated by reverse transcription-quantitative PCR and the relationship between circ-CCT3 and prognosis was analyzed by Kaplan-Meier curves. The oncogenic role of circ-CCT3 was confirmed in HCC cells through a cell counting kit-8 (CCK-8) assay, a colony formation assay, acridine orange/ethidium bromide double fluorescence staining, flow cytometry, a wound-healing assay and a Transwell assay. Bioinformatics prediction and luciferase reporter assays validated that circ-CCT3 facilitated HCC progression through the miR-1287-5p/TEA domain transcription factor 1 (TEAD1) axis. TEAD1 could then directly activate patched 1 and lysyl oxidase transcription, as analyzed by chromatin immunoprecipitation and luciferase reporter assays. The present study identified a novel circRNA, circ-CCT3, which may be used as a potential therapeutic target for HCC.

MiRNA-mediated EMT and CSCs in cancer chemoresistance

Cancer stem cells (CSCs) are a small group of cancer cells, which contribute to tumorigenesis and cancer progression. Cancer cells undergoing epithelial-to-mesenchymal transition (EMT) acquire the chemoresistant ability, which is regarded as an important feature of CSCs. Thus, there emerges an opinion that the generation of CSCs is considered to be driven by EMT. In this complex process, microRNAs (miRNAs) are found to play a key role. In order to overcome the drug resistance, inhibiting EMT as well as CSCs phenotype seem feasible. Thereinto, regulating the EMT- or CSCs-associated miRNAs is a crucial approach. Herein, we conduct this review to elaborate on the complicated interplay between EMT and CSCs in cancer chemoresistance, which is modulated by miRNAs. In addition, we elucidate the therapeutic strategy to overcome drug resistance through targeting EMT and CSCs.

Portrait of Cancer Stem Cells on Colorectal Cancer: Molecular Biomarkers, Signaling Pathways and miRNAome

Colorectal cancer (CRC) is a leading cause of cancer death worldwide, and about 20% is metastatic at diagnosis and untreatable. Increasing evidence suggests that the heterogeneous nature of CRC is related to colorectal cancer stem cells (CCSCs), a small cells population with stemness behaviors and responsible for tumor progression, recurrence, and therapy resistance. Growing knowledge of stem cells (SCs) biology has rapidly improved uncovering the molecular mechanisms and possible crosstalk/feedback loops between signaling pathways that directly influence intestinal homeostasis and tumorigenesis. The generation of CCSCs is probably connected to genetic changes in members of signaling pathways, which control self-renewal and pluripotency in SCs and then establish function and phenotype of CCSCs. Particularly, various deregulated CCSC-related miRNAs have been reported to modulate stemness features, controlling CCSCs functions such as regulation of cell cycle genes expression, epithelial-mesenchymal transition, metastasization, and drug-resistance mechanisms. Primarily, CCSC-related miRNAs work by regulating mainly signal pathways known to be involved in CCSCs biology. This review intends to summarize the epigenetic findings linked to miRNAome in the maintenance and regulation of CCSCs, including their relationships with different signaling pathways, which should help to identify specific diagnostic, prognostic, and predictive biomarkers for CRC, but also develop innovative CCSCs-targeted therapies.

Flavonoid display ability to target microRNAs in cancer pathogenesis

MicroRNAs (miRNAs) are non-coding, conserved, single-stranded nucleotide sequences involved in physiological and developmental processes. Recent evidence suggests an association between miRNAs' deregulation with initiation, promotion, progression, and drug resistance in cancer cells. Besides, miRNAs are known to regulate the epithelial-mesenchymal transition, angiogenesis, autophagy, and senescence in different cancer types. Previous reports proposed that apart from the antioxidant potential, flavonoids play an essential role in miRNAs modulation associated with changes in cancer-related proteins, tumor suppressor genes, and oncogenes. Thus, flavonoids can suppress proliferation, help in the development of drug sensitivity, suppress metastasis and angiogenesis by modulating miRNAs expression. In the present review, we summarize the role of miRNAs in cancer, drug resistance, and the chemopreventive potential of flavonoids mediated by miRNAs. The potential of flavonoids to modulate miRNAs expression in different cancer types demonstrate their selectivity and importance as regulators of carcinogenesis. Flavonoids as chemopreventive agents targeting miRNAs are extensively studied in vitro, in vivo, and pre-clinical studies, but their efficiency in targeting miRNAs in clinical studies is less investigated. The evidence presented in this review highlights the potential of flavonoids in cancer prevention/treatment by regulating miRNAs, although further investigations are required to validate and establish their clinical usefulness.

lncRNA-PACER upregulates COX-2 and PGE2 through the NF-κB pathway to promote the proliferation and invasion of colorectal-cancer cells

Background

p50-associated cyclooxygenase-2 extragenic RNA (PACER) is a recently identified antisense long non-coding RNA (lncRNA) located on the upstream of the promoter region of cyclooxygenase-2 (COX-2). Preliminary studies have suggested that PACER is involved in the regulation of COX-2 expression in macrophagocyte and osteosarcoma cells. However, the role of this lncRNA in colorectal cancer (CRC) remains elusive. Here, we investigated the expression of PACER and its effect on cell proliferation and invasion to explore the role of PACER in CRC.

Methods

Real-time quantitative PCR (RT-qPCR) analysis was used to evaluate the expression of PACER in CRC tissues and cells. Methyl thiazolyl tetrazolium (MTT) analysis was then used to investigate the inhibition effect of PACER knock-down in cell proliferation. The promoting role of this lncRNA on invasion by CRC cells was analysed by wound-healing assays, colony-formation assay, and transwell assays. We then used fluorescence in situ hybridization (FISH) to establish the subcellular localization of PACER. COX-2 protein levels were quantified by Western blot analysis and grayscale scanning analysis following the knock-down of PACER. Luciferase assay was carried out to monitor the modulation of the COX-2 promoter region by PACER. Tumor xenografts models were used to investigate the impact of PACER on the tumorigenesis of CRC cells in vivo. Enzyme-linked immunosorbent assay (ELISA) was then used to quantify prostaglandin E2 (PGE2) production upon knock-down of PACER.

Results

RT-qPCR analysis revealed that PACER was highly expressed in CRC tissues and cells, and a high PACER-expression level was associated with poor prognosis. MTT assay, wound-healing assay, colony-formation assay, and transwell assay revealed that PACER enhanced CRC-cell proliferation, invasion, and metastasis in vitro. Analysis of lncRNA localization by FISH showed that it mainly resided in the nucleus. RT-qPCR showed that PACER increased mRNA levels of COX-2. Western blot analysis demonstrated, under normal circumstances, that knock-down of PACER decreased the COX-2 protein level. In the case of p50 absence, COX-2 protein increased rapidly and remained highly expressed after knocking down PACER. Luciferase assay revealed that PACER modulated the COX-2 promoter region. Mouse xenograft models of CRC revealed that PACER promoted colorectal tumorigenesis in vivo. ELISA revealed that PACER knock-down inhibited PGE2 production.

Conclusions

PACER modulates COX-2 expression through the nuclear factor kappa B (NF-κB) pathway in CRC. An increased level of PACER enhances proliferation, migration, and invasion of tumor cells by increasing COX-2 and PGE2 synthesis.

Wnt Pathway: An Integral Hub for Developmental and Oncogenic Signaling Networks

The Wnt pathway is an integral cell-to-cell signaling hub which regulates crucial development processes and maintenance of tissue homeostasis by coordinating cell proliferation, differentiation, cell polarity, cell movement, and stem cell renewal. When dysregulated, it is associated with various developmental diseases, fibrosis, and tumorigenesis. We now better appreciate the complexity and crosstalk of the Wnt pathway with other signaling cascades. Emerging roles of the Wnt signaling in the cancer stem cell niche and drug resistance have led to development of therapeutics specifically targeting various Wnt components, with some agents currently in clinical trials. This review highlights historical and recent findings on key mediators of Wnt signaling and how they impact antitumor immunity and maintenance of cancer stem cells. This review also examines current therapeutics being developed that modulate Wnt signaling in cancer and discusses potential shortcomings associated with available therapeutics.

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.

Identification of microRNA-451a as a Novel Circulating Biomarker for Colorectal Cancer Diagnosis

Background

Colorectal cancer (CRC) is one of the leading causes of cancer death worldwide. Successful treatment of CRC relies on accurate early diagnosis, which is currently a challenge due to its complexity and personalized pathologies. Thus, novel molecular biomarkers are needed for early CRC detection.

Methods

Gene and microRNA microarray profiling of CRC tissues and miRNA-seq data were analyzed. Candidate microRNA biomarkers were predicted using both CRC-specific network and miRNA-BD tool. Validation analyses were carried out to interrogate the identified candidate CRC biomarkers.

Results

We identified miR-451a as a potential early CRC biomarker circulating in patient's serum. The dysregulation of miR-451a was revealed both in primary tumors and in patients' sera. Downstream analysis validated the tumor suppressor role of miR-451a and high sensitivity of miR-451a in CRC patients, further confirming its potential role as CRC circulation biomarker.

Conclusion

The miR-451a is a potential circulating biomarker for early CRC diagnosis.

Dual Effects of Non-Coding RNAs (ncRNAs) in Cancer Stem Cell Biology

The identification of cancer stem cells (CSCs) as initiators of carcinogenesis has revolutionized the era of cancer research and our perception for the disease treatment options. Additional CSC features, including self-renewal and migratory and invasive capabilities, have further justified these cells as putative diagnostic, prognostic, and therapeutic targets. Given the CSC plasticity, the identification of CSC-related biomarkers has been a serious burden in CSC characterization and therapeutic targeting. Over the past decades, a compelling amount of evidence has demonstrated critical regulatory functions of non-coding RNAs (ncRNAs) on the exclusive features of CSCs. We now know that ncRNAs may interfere with signaling pathways, vital for CSC phenotype maintenance, such as Notch, Wnt, and Hedgehog. Here, we discuss the multifaceted contribution of microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), as representative ncRNA classes, in sustaining the CSC-like traits, as well as the underlying molecular mechanisms of their action in various CSC types. We further discuss the use of CSC-related ncRNAs as putative biomarkers of high diagnostic, prognostic, and therapeutic value.

Autophagy-mediating microRNAs in cancer chemoresistance

Chemoresistance is a complex phenomenon responsible for failure in response to chemotherapy agents and more than 90% of deaths in cancer patients. MicroRNAs (miRNAs), as a subgroup of non-coding RNAs with lengths between 21 and 25 nucleotides, are involved in various cancer processes like chemoresistance via interacting with their target mRNAs and suppressing their expression. Autophagy is a greatly conserved procedure involving the lysosomal degradation of cytoplasmic contents and organelles to deal with environmental stresses like hypoxia and starvation. Autophagy contributes to response to chemotherapy agents: autophagy can act as a protective mechanism for mediating the resistance in response to chemotherapy or can induce autophagic cell death and mediate the sensitivity to chemotherapy. On the other hand, one of the processes targeted by microRNAs in the regulation of chemoresistance is autophagy. Hence, we studied the literatures on chemoresistance mechanisms, the miRNAs' role in cancer, and the miRNAs' role in chemoresistance by modulating autophagy. Graphical Abstract.

Detection of miR-1246, miR-23a and miR-451 in sera of colorectal carcinoma patients: a case-control study in Cairo University hospital

Background

Colorectal cancer (CRC) has high morbidity and mortality rates. Invasive techniques and other laboratory tests with variable sensitivity and specificity are currently used in diagnosis. Micro ribonucleic acids (miRNAs) have bio vital roles in cell proliferation and apoptosis. Dys-regulation of miRNAs is linked to tumour genesis. The objective of this study was to evaluate the specificity and sensitivity of serum non-invasive biomarkers (micro-RNAs), miR-1246, miR-23a, and miR-451in CRC patients.

Methods

Peripheral expression of three miRNAs (miR-1246, miR-23a and miR-451) was investigated in sera of 37 CRC Egyptian patients and 30 healthy controls, using quantitative real-time polymerase chain reaction trying to reach the optimal non-invasive combination of miRNAs.

Results

Serum miR-1246 was up-regulated in sera of CRC patients compared to normal controls (fold change = 3.55; P<0.001) and showed 100% sensitivity and 80% specificity in diagnosis of CRC. Serum miR-451 was significantly down-regulated in CRC patients (fold change = -4.86; p= 0.014), whereas, miR-23a was down-regulated but this was not statistically significant.

Conclusion

Up-regulation of miR-1246 and down-regulation of miR-451 in the sera of primary CRC Egyptian patients were confirmed with high sensitivity and specificity. Large-scale studies on a wider spectrum of miRNAs in Egyptian CRC patients are needed.

Circular RNA PRMT5 confers cisplatin-resistance via miR-4458/REV3L axis in non-small-cell lung cancer

Multifactor and multistep processes were elucidated to participate in the progression of non-small-cell lung cancer (NSCLC). Circular RNA 0031250 (circ-PRMT5) was a vital factor in NSCLC. However, the role of circ-PRMT5 in cisplatin (DDP)-resistance needed to be further highlighted. Expression profiles of circ-PRMT5, microRNA (miR)-4458, and EV3-like DNA-directed polymerase ζ catalytic subunit (REV3L) were detected using quantitative real-time polymerase chain reaction. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, flow cytometry, and transwell assays were performed to determine the half-maximal inhibitory concentration of DDP, cell viability, apoptosis, and invasion in vitro. Besides, the protein levels of REV3L and indicated proteins were examined by adopting western blot. Dual-luciferase reporter assay was performed to analyze the interaction between miR-4458 and circ-PRMT5 or REV3L. The functional role of circ-PRMT5 was explored using a xenograft tumor model. Levels of circ-PRMT5 and REV3L were markedly increased, while miR-4458 was downregulated in resistant tissues and cells. Knockdown of circ-PRMT5 enhanced cell apoptosis, DDP-sensitivity, and declined metastasis in NSCLC with DDP resistance. Besides, miR-4458 inhibition or REV3L upregulation could revert circ-PRMT5 absence-mediated effect on DDP-sensitivity in vitro. Mechanically, circ-PRMT5 was a sponge of miR-4458 to regulate REV3L. Importantly, circ-PRMT5 silencing could interact with DDP treatment expedite the decrease of tumor growth in vivo. Circ-PRMT5 promoted DDP resistance via REV3L by sponging miR-4458 in NSCLC, thus providing a novel therapeutic strategy for patients with NSCLC.

Epigenetic Regulation of Cancer Stem Cells by the Aryl Hydrocarbon Receptor Pathway

Compelling evidence has demonstrated that tumor bulk comprises distinctive subset of cells generally referred as cancer stem cells (CSCs) that have been proposed as a strong sustainer and promoter of tumorigenesis and therapeutic resistance. These distinguished properties of CSCs have raised interest in understanding the molecular mechanisms that govern the maintenance of these cells. Numerous experimental and epidemiological studies have demonstrated that exposure to environmental toxins such as the polycyclic aromatic hydrocarbons (PAHs) is strongly involved in cancer initiation and progression. The PAH-induced carcinogenesis is shown to be mediated through the activation of a cytosolic receptor, aryl hydrocarbon receptor (AhR)/Cytochrome P4501A pathway, suggesting a possible direct link between AhR and CSCs. Several recent studies have investigated the role of AhR in CSCs self-renewal and maintenance, however the molecular mechanisms and particularly the epigenetic regulations of CSCs by the AhR/CYP1A pathway have not been reviewed before. In this review, we first summarize the crosstalk between AhR and cancer genetics, with a particular emphasis on the mechanisms relevant to CSCs such as Wnt/β-catenin, Notch, NF-κB, and PTEN-PI3K/Akt signaling pathways. The second part of this review discusses the recent advances and studies highlighting the epigenetic mechanisms mediated by the AhR/CYP1A pathway that control CSC gene expression, self-renewal, and chemoresistance in various human cancers. Furthermore, the review also sheds light on the importance of targeting the epigenetic pathways as a novel therapeutic approach against CSCs.

Recent trends in targeting miRNAs for cancer therapy

OBJECTIVES

MicroRNAs (miRNAs) are a type of small noncoding RNA employed by the cells for gene regulation. A single miRNA, typically 22 nucleotides in length, can regulate the expression of numerous genes. Over the past decade, the study of miRNA biology in the context of cancer has led to the development of new diagnostic and therapeutic opportunities.

KEY FINDINGS

MicroRNA dysregulation is commonly associated with cancer, in part because miRNAs are actively involved in the mechanisms like genomic instabilities, aberrant transcriptional control, altered epigenetic regulation and biogenesis machinery defects. MicroRNAs can regulate oncogenes or tumour suppressor genes and thus when altered can lead to tumorigenesis. Expression profiling of miRNAs has boosted the possibilities of application of miRNAs as potential cancer biomarkers and therapeutic targets, although the feasibility of these approaches will require further validation.

SUMMARY

In this review, we will focus on how miRNAs regulate tumour development and the potential applications of targeting miRNAs for cancer therapy.

miR-140-3p enhances cisplatin sensitivity and attenuates stem cell-like properties through repressing Wnt/β-catenin signaling in lung adenocarcinoma cells

Lung adenocarcinoma (LUAD) is the most predominant subtype of non-small cell lung cancer (NSCLC) that is experiencing the fastest growth rate in incidence. Chemoresistance and the presence of cancer stem cells are considered to be the main obstacles preventing the successful treatment of patients with NSCLC, the molecular mechanism of which remains poorly understood. The present study aimed to investigate the effects of microRNA (miR)-140-3p on cisplatin sensitivity and stem cell-like properties of LUAD cells. Analysis of publicly available data demonstrated that miR-140-3p expression was downregulated in LUAD, and positively associated with the overall survival rate of patients. In addition, transfection with the miR-140-3p mimic reduced LUAD cell viability and induced apoptosis following treatment with cisplatin whilst decreasing stem cell-like properties. miR-140-3p overexpression was also found to attenuate cisplatin resistance and reduce stem cell-like properties in LUAD cells by suppressing Wnt/β-catenin signaling, all of which were reversed by the overexpression of β-catenin. Taken together, results of the present study suggest miR-140-3p to be an effective therapeutic strategy for patients with LUAD.

Roles of miRNAs in Colorectal Cancer: Therapeutic Implications and Clinical Opportunities

Colorectal cancer (CRC) is one of the most disseminated diseases across the globe engaging the digestive system. Various therapeutic methods from traditional to the state-of-the-art ones have been applied in CRC patients, however, the attempts have been unfortunate to lead to a definite cure. MiRNAs are a smart group of non-coding RNAs having the capabilities of regulating and controlling coding genes. By utilizing this stock-in-trade biomolecules, not only disease’s symptoms can be eliminated, there may also be a good chance for the complete cure of the disease in the near future. Herein, we provide a comprehensive review delineating the therapeutic relationship between miRNAs and CRC. To this, various clinical aspects of miRNAs which act as a tumor suppressor and/or an oncogene, their underlying cellular processes and clinical outcomes, and, in particular, their effects and expression level changes in patients treated with chemo- and radiotherapy are discussed. Finally, based on the results deducted from scientific research studies, therapeutic opportunities based on targeting/utilizing miRNAs in the preclinical as well as clinical settings are highlighted.

The Roles of Cancer Stem Cells and Therapy Resistance in Colorectal Carcinoma

Cancer stem cells (CSCs) are the main culprits involved in therapy resistance and disease recurrence in colorectal carcinoma (CRC). Results using cell culture, animal models and tissues from patients with CRC suggest the indispensable roles of colorectal CSCs in therapeutic failure. Conventional therapies target proliferating and mature cancer cells, while CSCs are mostly quiescent and poorly differentiated, thereby they can easily survive chemotherapeutic insults. The aberrant activation of Wnt/β-catenin, Notch, Hedgehog, Hippo/YAP (Yes-associated protein) and phosphatidylinositol 3-kinase/protein kinase B facilitates CSCs with excessive self-renewal and therapy resistance property in CRC. CSCs survive the chemo-radiotherapies by escaping therapy mediated DNA damage via altering the cell cycle checkpoints, increasing DNA damage repair capacity and by an efficient scavenging of reactive oxygen species. Furthermore, dysregulations of miRNAs e.g., miR-21, miR-93, miR-203, miR-215, miR-497 etc., modulate the therapeutic sensitivity of colorectal CSCs by regulating growth and survival signalling. In addition, a reversible quiescent G₀ state and the re-entering cell cycle capacity of colorectal CSCs can accelerate tumour regeneration after treatment. Moreover, switching to favourable metabolic signatures during a therapeutic regimen will add more complexity in therapeutic outcomes against CSCs. Therapeutic strategies targeting these underlying mechanisms of CSCs’ therapy resistance could provide a promising outcome, however, deep understanding and concerted research are necessary to design novel therapies targeting CSCs. To conclude, the understanding of these mechanisms of CSC in CRC could lead to the improved management of patients with CRC.

MicroRNA-375-3p enhances chemosensitivity to 5-fluorouracil by targeting thymidylate synthase in colorectal cancer

Resistance to chemotherapy is a major challenge for the treatment of patients with colorectal cancer (CRC). Previous studies have found that microRNAs (miRNAs) play key roles in drug resistance; however, the role of miRNA‐373‐3p (miR‐375‐3p) in CRC remains unclear. The current study aimed to explore the potential function of miR‐375‐3p in 5‐fluorouracil (5‐FU) resistance. MicroRNA‐375‐3p was found to be widely downregulated in human CRC cell lines and tissues and to promote the sensitivity of CRC cells to 5‐FU by inducing colon cancer cell apoptosis and cycle arrest and by inhibiting cell growth, migration, and invasion in vitro. Thymidylate synthase (TYMS) was found to be a direct target of miR‐375‐3p, and TYMS knockdown exerted similar effects as miR‐375‐3p overexpression on the CRC cellular response to 5‐FU. Lipid‐coated calcium carbonate nanoparticles (NPs) were designed to cotransport 5‐FU and miR‐375‐3p into cells efficiently and rapidly and to release the drugs in a weakly acidic tumor microenvironment. The therapeutic effect of combined miR‐375 + 5‐FU/NPs was significantly higher than that of the individual treatments in mouse s.c. xenografts derived from HCT116 cells. Our results suggest that restoring miR‐375‐3p levels could be a future novel therapeutic strategy to enhance chemosensitivity to 5‐FU.

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.

Aberrant Expressional Profiling of Known MicroRNAs in the Liver of Silver Carp (Hypophthalmichthys molitrix) Following Microcystin-LR Exposure Based on samllRNA Sequencing

Microcystin-LR (MC-LR) poses a serious threat to human health due to its hepatotoxicity. However, the specific molecular mechanism of miRNAs in MC-LR-induced liver injury has not been determined. The aim of the present study was to determine whether miRNAs are regulated in MC-LR-induced liver toxicity by using high-throughput sequencing. Our research demonstrated that 53 miRNAs and 319 miRNAs were significantly changed after 24 h of treatment with MC-LR (50 and 200 μg/kg, respectively) compared with the control group. GO enrichment analysis revealed that these target genes were related to cellular, metabolic, and single-organism processes. Furthermore, KEGG pathway analysis demonstrated that the target genes of differentially expressed miRNAs in fish liver were primarily involved in the insulin signaling pathway, PPAR signaling pathway, Wnt signaling pathway, and transcriptional misregulation in cancer. Moreover, we hypothesized that 4 miRNAs (miR-16, miR-181a-3p, miR-451, and miR-223) might also participate in MC-LR-induced toxicity in multiple organs of the fish and play regulatory roles according to the qPCR analysis results. Taken together, our results may help to elucidate the biological function of miRNAs in MC-LR-induced toxicity.

MicroRNA-451b Participates in Coronary Heart Disease By Targeting VEGFA

Coronary artery disease (CAD) is one of the main causes of hospitalization worldwide and has high morbidity. MicroRNAs (miRNAs) play an important role in the pathogenesis of cardiovascular diseases. miR-451 is a special miRNA that is involved in many cancers' development. At present, there is no research about miR-451 in coronary heart disease. In this study, we aimed to identify the action mechanism of miR-451 in coronary heart disease and human umbilical vein endothelial cells (HUVECs). In this study, we found that miR-451 is up-regulated in the peripheral blood of patients with coronary heart disease. Moreover, TargetScan and dual-luciferase reporter gene assay results showed that VEGFA is a direct target gene of miR-451. C (CCK-8) and flow cytometry assay results showed that miR-451 mimic significantly inhibits cell proliferation and promotes apoptosis in HUVECs. Moreover, we found that the role of miR-451 in HUVECs is associated with the PI3K-Akt-mTOR pathway. Taken together, the data indicates that miR-451 might be a novel bio-marker for coronary heart disease.

miR-451: A Novel Biomarker and Potential Therapeutic Target for Cancer

MicroRNAs (miRNAs) are endogenous, non-coding, single-stranded small RNAs involved in a variety of cellular processes, including ontogeny, cell proliferation, differentiation, and apoptosis. They can also function as oncogenes or tumor suppressor genes. Recent studies have revealed that miRNA-451 (miR-451) is involved in the regulation of various human physiological and pathological processes. Furthermore, it has been shown that miR-451 not only directly affects the biological functions of tumor cells but also indirectly affects tumor cell invasion and metastasis upon secretion into the tumor microenvironment via exosomes. Thus, miR-451 also influences the progression of tumorigenesis and drug resistance. This review summarizes the expression of miR-451 in various cancer types and the relationship between miR-451 and the diagnosis, treatment, and drug resistance of solid tumors. In addition, we address possible mechanisms of action of miR-451 and its potential application as a biomarker in the diagnosis and treatment of human cancers.

The integrative knowledge base for miRNA-mRNA expression in colorectal cancer

"miRNA colorectal cancer" (https://mirna-coadread.omics.si/) is a freely available web application for studying microRNA and mRNA expression and their correlation in colorectal cancer. To the best of our knowledge, "miRNA colorectal cancer" has the largest knowledge base of miRNA-target gene expressions and correlations in colorectal cancer, based on the largest available sample size from the same source of data. Data from high-throughput molecular profiling of 295 colon and rectum adenocarcinoma samples from The Cancer Genome Atlas was analyzed and integrated into our knowledge base. The objective of developing this web application was to help researchers to discover the behavior and role of miRNA-target gene interactions in colorectal cancer. For this purpose, results of differential expression and correlation analyses of miRNA and mRNA data collected in our knowledge base are available through web forms. To validate our knowledge base experimentally, we selected genes FN1, TGFB2, RND3, ZEB1 and ZEB2 and miRNAs hsa-miR-200a/b/c-3p, hsa-miR-141-3p and hsa-miR-429. Both approaches revealed a negative correlation between miRNA hsa-miR-200b/c-3p and its target gene FN1 and between hsa-miR-200a-3p and its target TGFB2, thus supporting the usefulness of the developed knowledge base.

Identification of potential molecular pathogenesis mechanisms modulated by microRNAs in patients with Intestinal Neuronal Dysplasia type B

This study proposed to determine global microRNA (miRNA) expression and miRNA-regulated pathways in Intestinal Neuronal Dysplasia type B (IND-B). Fifty patients (0-15 years old) with IND-B were included in the study. Peripheral blood samples were collected from all 50 patients and from 10 healthy asymptomatic children (controls). Rectal biopsies were collected from 29/50 patients; biopsy tissues were needle microdissected to isolate the different intestinal layers, for molecular analysis. Global miRNA expression was determined using TaqMan arrays. Correlation analysis between miRNA expression in plasma and biopsy samples as well as among tissues derived from the distinct intestinal layers was performed. Computational approaches were used for miRNA target prediction/identification of miRNA-regulated genes and enriched pathways biologically relevant to IND-B pathogenesis. miRNAs were statistically significantly deregulated (FC ≥ 2 and p ≤ 0.05) in submucosal and muscular layers: over-expressed (miR-146a and miR-146b) and under-expressed (miR-99a, miR-100, miR-130a, miR-133b, miR-145, miR-365, miR-374-5p, miR-451). Notably, let-7a-5p was highly over-expressed in patient plasma compared to healthy controls (FC = 17.4). In addition, miR-451 was significantly under-expressed in both plasma and all biopsy tissues from the same patients. Enriched pathways (p < 0.01) were axon guidance, nerve growth factor signalling, NCAM signalling for neurite out-growth, neuronal system and apoptosis. miRNA expression is deregulated in the submucosa and muscular layers of the rectum and detected in plasma from patients with IND-B. Biologically enriched pathways regulated by the identified miRNAs may play a role in IND-B disease pathogenesis, due to the activity related to the neurons of the enteric nervous system.

MicroRNA-451 is downregulated in the follicular fluid of women with endometriosis and influences mouse and human embryonic potential

BACKGROUND

Previous work demonstrated that there are numerous miRNAs in human follicular fluids, some of which are associated with reproductive diseases. In the current study, we sought to determine whether microRNAs (miRNAs) in the follicular fluid (FF) are differentially expressed between women with and without endometriosis and to uncover the association of miRNAs with the oocyte and embryonic development potential.

METHODS

FF was harvested from 30 women with endometriosis and 30 women without who underwent in vitro fertilization treatment at the University Hospital between February and December 2016. The FF samples were subjected to miRNA profiling and validation via quantitative reverse transcription polymerase chain reaction analysis. Mouse/human metaphase-I (MI) oocytes were harvested and micro-injected with an miR-451 inhibitor, and the effects of miR-451 knockdown on Wnt/WNT signalling genes were investigated.

RESULTS

Oocyte number, fertilization rate, and number of available embryos were decreased significantly in women with endometriosis relative to those without endometriosis. Hsa-miR-451 in FF was downregulated in endometriosis patients relative to control subjects (P < 0.01). Moreover, the proportions of mouse/human MI oocytes that developed into 2-pronuclei (2PN), 2-cell, 8-10-cell and blastocyst-stage embryos were affected by miR-451 knockdown in mouse/human oocytes. Components of the Wnt signalling pathway were aberrantly expressed in the mouse/human oocytes and embryos in the miR-451 inhibitor-injected group.

CONCLUSIONS

miR-451 was downregulated in FF samples from endometriosis patients and was modestly effective in distinguishing endometriosis patients from non-endometriosis patients. miR-451 downregulation in mouse and human oocytes affected pre-implantation embryogenesis by suppressing the Wnt signalling pathway. This miRNA might serve as a novel biomarker of oocyte and embryo quality in assisted reproductive treatment.

miRNAs derived from cancer-associated fibroblasts in colorectal cancer

Currently, the incidence of colorectal cancer (CRC) is increasing across the world. The cancer stroma exerts an impact on the spread, invasion and chemoresistance of CRC. The tumor microenvironment involves a complex interaction between cancer cells and stromal cells, for example, cancer-associated fibroblasts (CAFs). CAFs can promote neoplastic angiogenesis and tumor development in CRC. Mounting evidence suggests that many miRNAs are overexpressed (miR-21, miR-329, miR-181a, miR-199a, miR-382 and miR-215) in CRC CAFs, and these miRNAs can influence the spread, invasiveness and chemoresistance in neighboring tumor cells via paracrine signaling. Herein, we summarize the pathogenic roles of miRNAs and CAFs in CRC. Moreover, for first time, we highlight the miRNAs derived from CRC-associated CAFs and their roles in CRC pathogenesis.

miR‑486 acts as an oncogene and potential prognostic biomarker in renal cell carcinoma

MicroRNAs (miRNAs) are well established key players in tumorigenesis. Their emergence as potential diagnostic and prognostic biomarkers for cancer has demonstrated the importance of miRNAs in cancer biology. Although miR‑486 is implicated in many types of cancer, its role in renal cell carcinoma (RCC) remains undetermined. In the present study, real‑time quantitative PCR (qPCR), wound scratch assay, cell proliferation assay, Transwell migration assay and flow cytometry were utilized to detect the miR‑486 transcript and its role in proliferation, migration and apoptosis in RCC. The relationship between miR‑486 expression and clinicopathological variables or overall survival was analyzed using 96 formalin‑fixed paraffin‑embedded (FFPE) RCC samples. The results of the present study revealed significant upregulation of miR‑486 in RCC tissues and cell lines. Moreover, ectopic expression of miR‑486 promoted cell proliferation, mobility and inhibited apoptosis in 786‑O and ACHN cell lines. In addition, the Cox proportional hazard regression analysis revealed that patients with low expression of miR‑486 exhibited a markedly longer overall survival in the univariate and multivariate analyses. In conclusion, our findings indicate that miR‑486 may serve as a novel prognostic biomarker but may also be applied as a new therapeutic approach for the treatment of RCC.

miR-133b suppresses colorectal cancer cell stemness and chemoresistance by targeting methyltransferase DOT1L

Cancer stem cells (CSCs) are a subpopulation of chemoresistant cells that play a critical role in disease recurrence following chemotherapy. It has been reported that microRNA-133b (miR-133b) acts as a tumor suppressor in colorectal cancer (CRC). However, whether miR-133b is associated with CRC stemness and chemoresistance is not clear. In this study, we report that miR-133b is downregulated in colorectal spheroids, which are enriched with CSCs and display stem cell-like characteristics, including upreulation of CSCs surface markers and elevated chemoresistance. Additionally, miR-133b overexpression reduces CRC stemness and overrides chemoresistance to 5-Fluorouracil (5-FU) and oxaliplatin (OXP), indicating a negative role of miR-133b in regulating CRC stemness and chemoresistance. Moreover, miR-133b directly targets and suppresses the expression of disruptor of telomeric silencing 1-like (DOT1L), an exclusive H3K79 methyltransferase. Furthermore, miR-133b overexpression suppresses DOT1L-mediated H3K79me2 modification of stem cell genes, which is consistent with their downregulated transcription. More importantly, DOT1L restoration abrogates the suppressive effects of miR-133b on CRC stemness and chemoresistance, hence demonstrating that miR-133b regulates CRC stemness and chemoresistance through targeting DOT1L. Overall, these results imply that miR-133b might represent a novel therapeutic target in interfering CRC stemness and chemoresistance.