Identification of microRNA-487b as a negative regulator of liver metastasis by regulation of KRAS in colorectal cancer

The crosstalk between miRNAs and signaling pathways in human cancers: Potential therapeutic implications

MicroRNAs (miRNAs) are increasingly recognized as central players in the regulation of eukaryotic physiological processes. These small double stranded RNA molecules have emerged as pivotal regulators in the intricate network of cellular signaling pathways, playing significant roles in the development and progression of human cancers. The central theme in miRNA-mediated regulation of signaling pathways involves their ability to target and modulate the expression of pathway components. Aberrant expression of miRNAs can either promote or suppress key signaling events, influencing critical cellular processes such as proliferation, apoptosis, angiogenesis, and metastasis. For example, oncogenic miRNAs often promote cancer progression by targeting tumor suppressors or negative regulators of signaling pathways, thereby enhancing pathway activity. Conversely, tumor-suppressive miRNAs frequently inhibit oncogenic signaling by targeting key components within these pathways. This complex regulatory crosstalk underscores the significance of miRNAs as central players in shaping the signaling landscape of cancer cells. Furthermore, the therapeutic implications of targeting miRNAs in cancer are substantial. miRNAs can be manipulated to restore normal signaling pathway activity, offering a potential avenue for precision medicine. The development of miRNA-based therapeutics, including synthetic miRNA mimics and miRNA inhibitors, has shown promise in preclinical and clinical studies. These strategies aim to either enhance the activity of tumor-suppressive miRNAs or inhibit the function of oncogenic miRNAs, thereby restoring balanced signaling and impeding cancer progression. In conclusion, the crosstalk between miRNAs and signaling pathways in human cancers is a dynamic and influential aspect of cancer biology. Understanding this interplay provides valuable insights into cancer development and progression. Harnessing the therapeutic potential of miRNAs as regulators of signaling pathways opens up exciting opportunities for the development of innovative cancer treatments with the potential to improve patient outcomes. In this chapter, we provide an overview of the crosstalk between miRNAs and signaling pathways in the context of cancer and highlight the potential therapeutic implications of targeting this regulatory interplay.

Novel insights on perils and promises of miRNA in understanding colon cancer metastasis and progression

Colorectal cancer (CRC) is the third highest frequent malignancy and ultimate critical source of cancer-associated mortality around the world. Regardless of latest advances in molecular and surgical targeted medicines that have increased remedial effects in CRC patients, the 5-year mortality rate for CRC patients remains dismally low. Evidence suggests that microRNAs (miRNAs) execute an essential part in the development and spread of CRC. The miRNAs are a type of short non-coding RNA that exhibited to control the appearance of tumor suppressor genes and oncogenes. miRNA expression profiling is already being utilized in clinical practice as analytical and prognostic biomarkers to evaluate cancer patients' tumor genesis, advancement, and counteraction to drugs. By modulating their target genes, dysregulated miRNAs are linked to malignant characteristics (e.g., improved proliferative and invasive capabilities, cell cycle aberration, evasion of apoptosis, and promotion of angiogenesis). This review presents an updated summary of circulatory miRNAs, tumor-suppressive and oncogenic miRNAs, and the potential reasons for dysregulated miRNAs in CRC. Further we will explore the critical role of miRNAs in CRC drug resistance.

The Relationship between LRP6 and Wnt/β-Catenin Pathway in Colorectal and Esophageal Cancer

High expression of low-density lipoprotein receptor-related protein 6 (LRP6), a key component of the Wnt/β-catenin signaling pathway, is reported to be associated with malignant potential in some solid tumors including breast cancer and hepatocellular carcinoma. Few reports, however, have examined its function and clinical significance in colorectal cancers (CRC) demonstrating constitutive activation of Wnt signaling. Here, we compared the expression level and function of LRP6 in CRC with that of esophageal squamous cell carcinoma (ESCC) bearing few Wnt/β-catenin pathway mutations. On immunohistochemical staining, high LRP6 expression was noted in three of 68 cases (4.4%), and high β-catenin in 38 of 67 cases (56.7%) of CRC. High LRP6 expression was found in 21 of 82 cases (25.6%), and high β-catenin expression in 29 of 73 cases (39.7%) of ESCC. In our in vitro studies, LRP6 knockdown hardly changed Wnt signaling activity in CRC cell lines with mutations in Wnt signaling downstream genes. In contrast, in ESCC cell lines without Wnt signaling-related mutations, LRP6 knockdown significantly decreased Wnt signaling activity. LRP6 function may depend on constitutive activation of Wnt signaling.

Colorectal liver metastasis: molecular mechanism and interventional therapy

Colorectal cancer (CRC) is one of the most frequently occurring malignancy tumors with a high morbidity additionally, CRC patients may develop liver metastasis, which is the major cause of death. Despite significant advances in diagnostic and therapeutic techniques, the survival rate of colorectal liver metastasis (CRLM) patients remains very low. CRLM, as a complex cascade reaction process involving multiple factors and procedures, has complex and diverse molecular mechanisms. In this review, we summarize the mechanisms/pathophysiology, diagnosis, treatment of CRLM. We also focus on an overview of the recent advances in understanding the molecular basis of CRLM with a special emphasis on tumor microenvironment and promise of newer targeted therapies for CRLM, further improving the prognosis of CRLM patients.

microRNA Profile Associated with Positive Lymph Node Metastasis in Early-Stage Cervical Cancer

Lymph node metastasis (LNM) is an important prognostic factor in cervical cancer (CC). In early stages, the risk of LNM is approximately 3.7 to 21.7%, and the 5-year overall survival decreases from 80% to 53% when metastatic disease is identified in the lymph nodes. Few reports have analyzed the relationship between miRNA expression and the presence of LNM. The aim of this study was to identify a subset of miRNAs related to LNM in early-stage CC patients. Formalin-fixed paraffin-embedded tissue blocks were collected from patients with early-stage CC treated by radical hysterectomy with lymphadenectomy. We analyzed samples from two groups of patients—one group with LNM and the other without LNM. Global miRNA expression was identified by microarray analysis, and cluster analysis was used to determine a subset of miRNAs associated with LNM. Microarray expression profiling identified a subset of 36 differentially expressed miRNAs in the two groups (fold change (FC) ≥ 1.5 and p < 0.01). We validated the expression of seven miRNAs; miR-487b, miR-29b-2-5p, and miR-195 were underexpressed, and miR-92b-5p, miR-483-5p, miR-4534, and miR-548ac were overexpressed according to the microarray experiments. This signature exhibited prognostic value for identifying early-stage CC patients with LNM. These findings may help detect LNM that cannot be observed in imaging studies.

Interplay between K-RAS and miRNAs

K-RAS is frequently mutated in cancers, and its overactivation can lead to oncogene-induced senescence (OIS), a barrier to cellular transformation. Feedback onto K-RAS limits its signaling to avoid senescence while achieving the appropriate level of activation that promotes proliferation and survival. Such regulation could be mediated by miRNAs, as aberrant RAS signaling and miRNA activity coexist in several cancers, with miRNAs acting both up- and downstream of K-RAS. Several miRNAs both regulate and are regulated by K-RAS, suggesting a noncoding RNA-based feedback mechanism. Functional interactions between K-RAS and the miRNA machinery have also begun to unfold. This review comprehensively surveys the state of knowledge connecting K-RAS to miRNA function and proposes a model for the regulation of K-RAS signaling by noncoding RNAs.

Epigenetic Regulation of the Wnt/β-Catenin Signaling Pathway in Cancer

Studies over the past four decades have elucidated the role of Wnt/β-catenin mediated regulation in cell proliferation, differentiation and migration. These processes are fundamental to embryonic development, regeneration potential of tissues, as well as cancer initiation and progression. In this review, we focus on the epigenetic players which influence the Wnt/β-catenin pathway via modulation of its components and coordinated regulation of the Wnt target genes. The role played by crosstalk with other signaling pathways mediating tumorigenesis is also elaborated. The Hippo/YAP pathway is particularly emphasized due to its extensive crosstalk via the Wnt destruction complex. Further, we highlight the recent advances in developing potential therapeutic interventions targeting the epigenetic machinery based on the characterization of these regulatory networks for effective treatment of various cancers and also for regenerative therapies.

Emerging Mechanisms and Treatment Progress on Liver Metastasis of Colorectal Cancer

Colorectal cancer is currently the third largest malignant tumor in the world, with high new cases and high mortality. Metastasis is one of the most common causes of death of colorectal cancer, of which liver metastasis is the most fatal. Since the beginning of the Human Genome Project in 2001, people have gradually recognized the 3 billion base pairs that make up the human genome, of which only about 1.5% of the nucleic acid sequences are used for protein coding, including proto-oncogenes and tumor suppressor genes. A large number of differences in the expression of proto-oncogenes and tumor suppressor genes have also been found in the study of colorectal cancer, which proves that they are also actively involved in the progression of colorectal cancer and promote the occurrence of liver metastasis. Except for 1.5% of the coding sequence, the rest of the nucleic acid sequence does not encode any protein, which is called non-coding RNA. With the deepening of research, genome sequences without protein coding potential that were originally considered “junk sequences” may have important biological functions. Many years of studies have found that a large number of abnormal expression of ncRNA in colorectal cancer liver metastasis, indicating that ncRNA plays an important role in it. To explore the role and mechanism of these coding sequences and non-coding RNA in liver metastasis of colorectal cancer is very important for the early diagnosis and treatment of liver metastasis of colorectal cancer. This article reviews the coding genes and ncRNA that have been found in the study of liver metastasis of colorectal cancer in recent years, as well as the mechanisms that have been identified or are still under study, as well as the clinical treatment of liver metastasis of colorectal cancer.

Clinical significance of serum miR-487b in HBV-related hepatocellular carcinoma and its potential mechanism

BACKGROUND

Hepatocellular carcinoma (HCC) is a malignant tumour with high mortality. In recent years, microRNA (miRNA) has been recognized in the diagnosis and prognosis of cancer. miR-487b has been found to play a role in a variety of cancers. The purpose of this study is to explore the role of miR-487b in the diagnosis and prognosis of hepatitis B virus (HBV)-related HCC, and its influence on the biological behaviour of HCC cells.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) method was used to detect the expression level of miR-487b in the serum of HCC patients, HBV patients, and healthy people. The ROC curve was used to evaluate the role of miR-487b in the diagnosis of HCC. The prognostic significance of miR-487b in HCC was analyzed by the Kaplan-Meier survival curve and Cox regression model. The effects of miR-487b on cell proliferation, migration, and invasion were explored through MTT assay and transwell assays.

RESULTS

The expression level of miR-487b in the serum of HBV-related HCC patients was significantly higher than that of CHB patients and normal healthy people. The expression level of miR-487b can distinguish HCC patients from CHB patients or normal healthy people. High expression of miR-487b was associated with poor prognosis, which could be used as an independent prognostic factor for HCC. The upregulation of miR-487b promoted cell proliferation, migration, and invasion.

CONCLUSION

miR-487b can be used as a biomarker for the diagnosis and prognosis of HCC.

The Role of Noncoding RNAs in the Regulation of Anoikis and Anchorage-Independent Growth in Cancer

Cancer is a global health concern, and the prognosis of patients with cancer is associated with metastasis. Multistep processes are involved in cancer metastasis. Accumulating evidence has shown that cancer cells acquire the capacity of anoikis resistance and anchorage-independent cell growth, which are critical prerequisite features of metastatic cancer cells. Multiple cellular factors and events, such as apoptosis, survival factors, cell cycle, EMT, stemness, autophagy, and integrins influence the anoikis resistance and anchorage-independent cell growth in cancer. Noncoding RNAs (ncRNAs), such as microRNAs (miRNAs) and long noncoding RNAs (lncRNAs), are dysregulated in cancer. They regulate cellular signaling pathways and events, eventually contributing to cancer aggressiveness. This review presents the role of miRNAs and lncRNAs in modulating anoikis resistance and anchorage-independent cell growth. We also discuss the feasibility of ncRNA-based therapy and the natural features of ncRNAs that need to be contemplated for more beneficial therapeutic strategies against cancer.

Non-coding RNAS and colorectal cancer liver metastasis

More than 50% of colorectal cancer (CRC) deaths are attributed to metastasis, and the liver is the most common distant metastatic site of CRC. The molecular mechanisms underlying CRC liver metastasis are very complicated and remain largely unknown. Accumulated evidence has shown that non-coding RNAs (NcRNAs) play critical roles in tumor development and progression. Here we reviewed the roles and underlying mechanisms of NcRNAs in CRC liver metastasis.

miR-487b and TRAK2 that form an axis to regulate the aggressiveness of osteosarcoma, are potential therapeutic targets and prognostic biomarkers

To investigate the effect of microRNA-487b (miR-487b) as well as the underlying mechanism in osteosarcoma (OS). Data downloaded from the Gene Expression Omnibus (GEO) database were used to analyze the expression and prognostic value of miR-487b/TRAK2. Cell counting kit-8, colony formation, and transwell assays were performed to investigate the biological functions of miR-487b and TRAK2. Luciferase reporter assay was applied to confirm the interactions between miR-487b and TRAK2. miR-487b was overexpressed in OS tissues and was inversely associated with the prognosis of OS patients. We discovered that miR-487b could contribute to the proliferative, clonogenic, invasive, and migratory capabilities of OS cells. Through target prediction using miRWalk and differential expression analysis based on the GEO data set, trafficking kinesin protein 2 (TRAK2) was recognized as a potential target of miR-487b, which was further verified by luciferase reporter assay. The expression of TRAK2 was decreased in OS tissues compared with normal tissues and was positively correlated with the prognosis of OS patients. A negative relevance was presented between the expression of miR-487b and TRAK2 in OS cells. Of note, further mechanistic analyses indicated that TRAK2 was implicated in the regulatory effect of miR-487b on the cell malignant behaviors in OS. To sum up, these results demonstrated that miR-487b played an oncogenic role in OS progression via directly targeting TRAK2, which could advance the development of cancer treatment.

The potential role of regulatory microRNAs of RAS/MAPK signaling pathway in the pathogenesis of colorectal cancer

Colorectal cancer (CRC) is the leading cause of cancer death worldwide. Dysregulation of RAS/MAPK signaling axis is frequently found in CRC patients. The RAS/MAPK axis regulates cancer cell proliferation, apoptosis, inflammation, migration, and metastasis. Oncogenic or tumor-suppressor microRNAs (miRNAs) for RAS/MAPK signaling play a key role in the pathogenesis of CRC and are considered as novel potential biomarkers for diagnosis and prognosis of human malignancies. This review summarizes the current knowledge of mechanisms of action of RAS/MAPK miRNAs in the development and progression of CRC for a better understanding and hence a better management of this disease.

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.

DNA methylation-regulated and tumor-suppressive roles of miR-487b in colorectal cancer via targeting MYC, SUZ12, and KRAS

Human colorectal cancer (CRC), characterized by its high morbidity and lethality, seriously threatens human health and lives. MicroRNA‐487b (miR‐487b) is currently reported to be aberrantly expressed in several tumors, but the detailed functions and underlying mechanisms of miR‐487b in CRC remain unclear. Here, we found that miR‐487b is downregulated in CRC cell lines and is markedly decreased in tumor specimens derived from CRC patients. MiR‐487b inhibits cell proliferation, migration and invasion and promotes the apoptosis of CRC cells in vitro. Statistical analysis of clinical samples indicates that miR‐487b may serve as a biomarker for early CRC diagnosis. Inverse correlations between the expression levels of MYC, SUZ12, and KRAS and that of miR‐487b exist in vitro and in CRC patient tissue specimens. Further experiments demonstrated the regulatory effects of miR‐487b on MYC, SUZ12, and KRAS, and the disruption of these genes partially restores the miR‐487b inhibitor‐induced phenotype. Additionally, miR‐487b promoter region is in a DNA hypermethylated condition and the DNA methyltransferase inhibitor 5‐aza‐2’‐deoxycytidine (5‐Aza) increases the levels of miR‐487b but suppresses the expression of MYC, SUZ12, and KRAS in a time‐ and concentration‐dependent manner in CRC cells. Collectively, miR‐487b is regulated by DNA methylation and it functions as a tumor suppressor in CRC mainly through targeting MYC, SUZ12, and KRAS. Our study provides insight into the regulatory network in CRC cells, offering a new target for treating CRC patients.

The Impact of miRNA in Colorectal Cancer Progression and Its Liver Metastases

Colorectal cancer (CRC) is one of the most commonly diagnosed malignancies with a high incidence and mortality rate. An essential challenge in colorectal cancer management is to identify new prognostic factors that could better estimate the evolution and treatment responses of this disease. Considering their role in cancer development, progression and metastasis, miRNAs have become an important class of molecules suitable for cancer biomarkers discovery. We performed a systematic search of studies investigating the role of miRNAs in colorectal progression and liver metastasis published until October 2018. In this review, we present up-to-date information regarding the specific microRNAs involved in CRC development, considering their roles in alteration of Wnt/βcatenin, EGFR, TGFβ and TP53 signaling pathways. We also emphasize the role of miRNAs in controlling the epithelial⁻mesenchymal transition of CRC cells, a process responsible for liver metastasis in a circulating tumor cell-dependent manner. Furthermore, we discuss the role of miRNAs transported by CRC-derived exosomes in mediating liver metastases, by preparing the secondary pre-metastatic niche and in inducing liver carcinogenesis in a Dicer-dependent manner.

Emerging paradigms in the treatment of liver metastases in colorectal cancer

Efforts to combat colorectal cancer have benefited from improved screening and surveillance, which facilitates early detection. The survival rate associated with diagnosis at stage I is approximately 90%. However, progress in improving survival in metastatic colorectal cancer (mCRC) has been minimal. This review focuses on mCRC with special emphasis on the molecular aspects of liver metastases, which is one of the most frequently involved organ site. Better molecular evidence is required to guide the decisions for surgical and other interventions used in the clinical management of mCRC. Results from different treatment modalities have exposed significant gaps in the existing paradigms of the mCRC management. Indeed there is a critical need to better understand molecular events and pathways that lead to colorectal cancer liver metastasis. Such a focused approach may help identify biomarkers and drug targets that can be useful in the clinical applications. With this focus, we provide an account of the molecular pathways involved in the spread of CRC to the liver. Specifically, the molecular changes at the DNA and RNA levels that are associated with liver metastases are discussed. Similarly, we describe relevant microRNAs that are identified as regulators of gene expression and can also serve as biomarkers. Conventionally applied biomarkers are not yet specific and sensitive enough to be relied in routine clinical decision making. Hence search for novel biomarkers is critically needed especially if these can be utilized using liquid biopsies. This review provides a comprehensive analysis of current molecular evidence along with potential future directions that could reshape the diagnostic and management paradigms and thus mitigate the devastating impact of colorectal cancer metastasis to the liver.

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

Background

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

Materials and methods

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

Results

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

Conclusion

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

Therapeutic Suppression of miR-4261 Attenuates Colorectal Cancer by Targeting MCC

The mutated in colorectal cancer (MCC) gene is an important colorectal tumor suppressor gene, although few studies have reported the microRNA(s) that could directly target MCC in colorectal cancer. Here, we used microRNA (miRNA) target prediction algorithms, and previously reported microarray data in human colorectal cancer found that only miR-4261 was predicted by all three databases to directly target MCC. Based on specimens from our own cohort of colorectal cancer patients, we further demonstrated that miR-4261 was overexpressed in colorectal cancer. Interestingly, overexpression of miR-4261 could enhance cell proliferation and G1/S phase transition of cell cycle, and promote cell migration in HCT116 and HT29 cells, while inhibition of miR-4261 had opposite effects. Luciferase reporter assay and western blot analysis confirmed MCC as a direct target of miR-4261. MCC small interfering RNA (siRNA) could abolish the suppressive effects of miR-4261 inhibitor on cell proliferation and migration in HCT116 and HT29 cell lines. Finally, we showed that therapeutic intervention with lentivirus-based miR-4261 sponge injection could effectively reduce tumor growth and inhibit cell proliferation in colorectal cancer xenograft. Collectively, our study is the first one to unravel the functional role of miR-4261, and it provides strong evidence that inhibition of miR-4261 through targeting of MCC might exert a therapeutic effect for colorectal cancer.

MicroRNAs: Potential candidates for diagnosis and treatment of colorectal cancer

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

[The Role of MicroRNAs in Colorectal Cancer]

Colorectal cancer (CRC) is one of the leading causes of cancer related deaths in the world. Many oncogenes and tumor suppressor genes are involved in the development of CRC. MicroRNAs (miRNAs) are a class of small, non-coding, endogenous RNAs in animals and plants. Recent studies have shown that miRNAs are associated with the mediation process of tumorigenesis, including inflammation, cell cycle, stress response, differentiation, apoptosis, migration, and invasion in cancer. These miRNAs have been linked to the development of CRC and recently studied as new potential biomarkers in the diagnosis and treatment for CRC. Specific miRNAs expression patterns help distinguish CRC from other colon-related diseases, and miRNAs can target the oncogenes and regulatory molecular pathways. Recent studies have demonstrated the restoration of tumor suppressive miRNAs and inhibition of oncogenic miRNAs for CRC treatment. Herein, we describe the diagnostic and therapeutic roles of miRNAs in CRC.