MicroRNAs: Multifaceted Regulators of Colorectal Cancer Metastasis and Clinical Applications

ERO1α promotes the proliferation and inhibits apoptosis of colorectal cancer cells by regulating the PI3K/AKT pathway

Endoplasmic reticulum oxidoreductin 1α (ERO1α) is an oxidase that exists in the endoplasmic reticulum and plays an important role in regulating oxidized protein folding and tumor malignant progression. However, the specific role and mechanism of ERO1α in the progression of colorectal cancer (CRC) have not yet been fully elucidated. In this study, 280 specimens of CRC tissues and adjacent noncancerous tissues were collected to detect the expression of ERO1α and analyze the clinical significance. ERO1α was stably knocked-down in RKO and HT29 CRC cells to investigate its function and mechanism in vitro and in vivo. We found that ERO1α was remarkably upregulated in CRC tissues and high ERO1α expression is associated with N stage and poor prognosis of CRC patients. ERO1α knockdown in CRC cells significantly inhibited the proliferation and induced apoptosis while inactivating the PI3K/AKT pathway. Rescue assays revealed that AKT activator 740Y-P could reverse the effects on proliferation and apoptosis of ERO1α knockdown in CRC cells. In vivo tumorigenicity assay also confirmed that ERO1α knockdown suppressed tumor growth. Taken together, our findings demonstrated ERO1α promotes the proliferation and inhibits apoptosis of CRC cells by regulating the PI3K/AKT pathway. High expression of ERO1α is associated with poor prognosis in CRC patients, and ERO1α could be a potential therapeutic target for CRC.

Roles of anoikis in colorectal cancer therapy and the assessment of anoikis-regulatory molecules as therapeutic targets

Colorectal cancer (CRC) is a deadly malignancy and therapeutic approaches for CRC are evolving every day. Anoikis is a key mechanism for programmed cell death of cancer cells that undergo anchorage-independent growth at a different matrix than the one which is expected. Yet, anoikis is a less studied mechanism of cell death in comparison to other mechanisms such as apoptosis. Relating to this, resistance to anoikis among cancer cells remains critical for improved metastasis and survival in a new environment evading anoikis. Since CRC cells have the ability to metastasize from proximal sites to secondary organs such as liver and promote cancer in those distant sites, a clear knowledge of the mechanisms essential for anchorage-independent growth and subsequent metastasis is necessary to counteract CRC progression and spread. Therefore, the identification of novel drug candidates and studying the roles of anoikis in assisting CRC therapy using such drugs can prevent anchorage-independent cancer cell growth. Additionally, the identification of novel biomarkers or therapeutic targets seems essential for implementing superior therapy, impeding relapse among malignant cells and improving the survival rate of clinical patients. As there are no reviews published on this topic till date, anoikis as a mechanism of cell death and its therapeutic roles in CRC are discussed in this review. In addition, several molecules were identified as therapeutic targets for CRC.

MicroRNAs (miRNAs): Novel potential therapeutic targets in colorectal cancer

Colorectal cancer (CRC) is the most common malignant tumor and one of the most lethal malignant tumors in the world. Despite treatment with a combination of surgery, radiotherapy, and/or systemic treatment, including chemotherapy and targeted therapy, the prognosis of patients with advanced CRC remains poor. Therefore, there is an urgent need to explore novel therapeutic strategies and targets for the treatment of CRC. MicroRNAs (miRNAs/miRs) are a class of short noncoding RNAs (approximately 22 nucleotides) involved in posttranscriptional gene expression regulation. The dysregulation of its expression is recognized as a key regulator related to the development, progression and metastasis of CRC. In recent years, a number of miRNAs have been identified as regulators of drug resistance in CRC, and some have gained attention as potential targets to overcome the drug resistance of CRC. In this review, we introduce the miRNAs and the diverse mechanisms of miRNAs in CRC and summarize the potential targeted therapies of CRC based on the miRNAs.

Intracellular and extracellular factors of colorectal cancer liver metastasis: a pivotal perplex to be fully elucidated

Metastasis is the leading cause of death in colorectal cancer (CRC) patients, and the liver is the most common site of metastasis. Tumor cell metastasis can be thought of as an invasion-metastasis cascade and metastatic organotropism is thought to be a process that relies on the intrinsic properties of tumor cells and their interactions with molecules and cells in the microenvironment. Many studies have provided new insights into the molecular mechanism and contributing factors involved in CRC liver metastasis for a better understanding of the organ-specific metastasis process. The purpose of this review is to summarize the theories that explain CRC liver metastasis at multiple molecular dimensions (including genetic and non-genetic factors), as well as the main factors that cause CRC liver metastasis. Many findings suggest that metastasis may occur earlier than expected and with specific organ-anchoring property. The emergence of potential metastatic clones, the timing of dissemination, and the distinct routes of metastasis have been explained by genomic studies. The main force of CRC liver metastasis is also thought to be epigenetic alterations and dynamic phenotypic traits. Furthermore, we review key extrinsic factors that influence CRC cell metastasis and liver tropisms, such as pre-niches, tumor stromal cells, adhesion molecules, and immune/inflammatory responses in the tumor microenvironment. In addition, biomarkers associated with early diagnosis, prognosis, and recurrence of liver metastasis from CRC are summarized to enlighten potential clinical practice, including some markers that can be used as therapeutic targets to provide new perspectives for the treatment strategies of CRC liver metastasis.

Novel biomarkers of microRNAs in gastric cancer; an overview from diagnosis to treatment

The fourth frequent disease in the world and the second cause of cancer-related death is gastric cancer (GC). In this way, over 80% of diagnoses are made in the middle to advanced degrees of the disease, underscoring the requirement for innovative biomarkers that can be identified quickly. Meaningly, biomarkers that can complement endoscopic diagnosis and be used to detect patients with a high risk of GC are desperately needed. These biomarkers will allow for the accurate prediction of therapy response and prognosis in GC patients, as well as the development of an optimal treatment strategy for each individual. Conspicoiusly, microRNAs (miRNAs) and small noncoding RNA regulates the expression of target mRNA and thereby modifies critical biological mechanisms. According to the data, abnormally miRNAs expression in GC is linked to tumor growth, carcinogenesis, aggression and distant metastasis. Importantly, miRNA expression patterns and next-generation sequencing (NGS) can also be applied to analyze kinds of tissues and cancers. Given the high death rates and poor prognosis of GC, and the absence of a clinical diagnostic factor that is adequately sensitive to GC, research into novel sensitive and specific markers for GC diagnosis is critical. In this review,we evaluate the latest research findings that suggest the feasibility and clinical utility of miRNAs in GC.

Long noncoding RNA LINC00649 functions as a microRNA‑432‑5p sponge to facilitate tumourigenesis in colorectal cancer by upregulating HDGF

Long intergenic nonprotein coding RNA 649 (LINC00649) is a functional regulator in acute myeloid leukaemia. However, the contribution of LINC00649 in colorectal cancer (CRC) has yet to be confirmed. Accordingly, the present investigation was devoted to exploring the detailed functions of LINC00649 and reveal the mechanisms underlying the LINC00649-induced promotion of CRC progression. LINC00649 expression in CRC was investigated by reverse transcription-quantitative PCR. Knockdown of LINC00649 was achieved using small interfering RNAs or short hairpin RNA, followed by functional experiments. The binding between LINC00649 and microRNA (miR)-432-5p was predicted by a bioinformatics tool, and corroborated by luciferase reporter assay and RNA immunoprecipitation. In the present study, LINC00649 was expressed at a high level in CRC. The aberrant expression of LINC00649 exhibited an inverse association with CRC patient prognosis. Functionally, the downregulation of LINC00649 exerted anticarcinogenic activities in CRC by decreasing cell proliferation, migration, and invasion and inducing cell apoptosis. Furthermore, the growth of CRC cells in vivo was attenuated after LINC00649 deficiency. Mechanistically, LINC00649 functioned as a competitive endogenous RNA by competitively binding to miR-432-5p in CRC cells, inducing an increase in hepatoma-derived growth factor (HDGF). Ultimately, functional rescue experiments highlighted that the exogenous introduction of miR-432-5p inhibitor or HDGF overexpression plasmid partially abated the inhibitory effects of LINC00649 silencing. In conclusion, LINC00649 promoted the aggressiveness of CRC cells by adjusting the miR-432-5p/HDGF axis. Thus, the LINC00649/miR-432-5p/HDGF pathway may be a promising target for CRC therapy.

Supervised Learning Based Systemic Inflammatory Markers Enable Accurate Additional Surgery for pT1NxM0 Colorectal Cancer: A Comparative Analysis of Two Practical Prediction Models for Lymph Node Metastasis

Purpose

Predicting lymph node metastasis (LNM) after endoscopic resection is crucial in determining whether patients with pT1NxM0 colorectal cancer (CRC) should undergo additional surgery. This study was aimed to develop a predictive model that can be used to reduce the current likelihood of overtreatment.

Patients and Methods

We recruited a total of 1194 consecutive CRC patients with pT1NxM0 who underwent endoscopic or surgical resection at the Gezhouba Central Hospital of Sinopharm between January 1, 2006, and August 31, 2021. The random forest classifier (RFC) and generalized linear algorithm (GLM) were used to screen out the variables that greatly affected the LNM prediction, respectively. The area under the curve (AUC) and decision curve analysis (DCA) were applied to assess the accuracy of predictive models.

Results

Analysis identified the top 10 candidate factors including depth of submucosal invasion, neutrophil-lymphocyte ratio (NLR), platelet lymphocyte ratio (PLR), platelet-to-neutrophil ratio(PNR), venous invasion, poorly differentiated clusters, tumor budding, grade, lymphatic vascular invasion, and background adenoma. The performance of the GLM achieved the highest AUC of 0.79 (95% confidence interval [CI]: 0.30 to 1.28) in the training cohort and robust AUC of 0.80 (95% confidence interval [CI]: 0.36 to 1.24) in the validation cohort. Meanwhile, the RFC exhibited a robust AUC of 0.84 (95% confidence interval [CI]: 0.40 to 1.28) in the training cohort and a high AUC of 0.85 (95% CI: 0.41 to 1.29) in the validation cohort. DCAs also showed that the RFC had superior predictive ability.

Conclusion

Our supervised learning-based model incorporating histopathologic parameters and inflammatory markers showed a more accurate predictive performance compared to the GLM. This newly supervised learning-based predictive model can be used to determine an individually tailored treatment strategy.

Mesenchymal Stem Cell-derived Extracellular Vesicles Transmitting MicroRNA-34a-5p Suppress Tumorigenesis of Colorectal Cancer Through c-MYC/DNMT3a/PTEN Axis

Mesenchymal stem cell–derived extracellular vesicles (MSC-EV) can transport microRNAs (miRNAs) into colorectal cancer (CRC) cells, thus to inhibit the malignant phenotype of cancer cells. Whether MSC-EV could deliver miR-34a-5p to suppress CRC development was surveyed through the research. miR-34a-5p, c-MYC, DNA methyltransferase 3a (DNMT3a), and phosphatase and tensin homolog deleted on chromosome 10 (PTEN) expression were measured in CRC tissues and cell lines. miR-34a-5p and c-MYC expression were altered by transfection in HCT-116 cells. MSC-EV were transfected with miR-34a-5p- and c-MYC-related oligonucleotides and co-cultured with HCT-116 cells. HCT-116 cell growth after treatment was observed. Furthermore, the functional roles of miR-34a-5p and c-MYC were explored in vivo. The combined interactions of miR-34a-5p/c-MYC/DNMT3a/PTEN axis were assessed. miR-34a-5p and PTEN were downregulated while c-MYC and DNMT3a were upregulated in CRC. Depletion of miR-34a-5p drove while that of c-MYC restricted CRC cell growth. MSC-EV retarded CRC progression. Moreover, MSC-EV carrying overexpressed miR-34a-5p or depleted c-MYC further disrupted CRC cell progression. miR-34a-5p targeted c-MYC to regulate DNMT3a and PTEN. c-MYC overexpression abrogated EV-derived miR-34a-5p upregulation-induced effects on CRC. Restoring miR-34a-5p or depleting c-MYC in MSC-EV limited CRC tumor formation. MSC-EV-derived miR-34a-5p depresses CRC development through modulating the binding of c-MYC to DNMT3a and epigenetically regulating PTEN.

Tackling Tumour Cell Heterogeneity at the Super-Resolution Level in Human Colorectal Cancer Tissue

Simple Summary

Tumour cell heterogeneity is the most fundamental problem in cancer diagnosis and therapy. Micro-diagnostic technologies able to differentiate the heterogeneous molecular, especially metastatic, potential of single cells or cell clones already within early primary tumours of carcinoma patients would be of utmost importance. Single molecule localisation microscopy (SMLM) has recently allowed the imaging of subcellular features at the nanoscale. However, the technology has mostly been limited to cultured cell lines only. We introduce a first-in-field approach for quantitative SMLM-analysis of chromatin nanostructure in individual cells in resected, routine-pathology colorectal carcinoma patient tissue sections, illustrating, as a first example, changes in nuclear chromatin nanostructure and microRNA intracellular distribution within carcinoma cells as opposed to normal cells, chromatin accessibility and microRNAs having been shown to be critical in gene regulation and metastasis. We believe this technology to have an enormous potential for future differential diagnosis between individual cells in the tissue context.

Abstract

Tumour cell heterogeneity, and its early individual diagnosis, is one of the most fundamental problems in cancer diagnosis and therapy. Single molecule localisation microscopy (SMLM) resolves subcellular features but has been limited to cultured cell lines only. Since nuclear chromatin architecture and microRNAs are critical in metastasis, we introduce a first-in-field approach for quantitative SMLM-analysis of chromatin nanostructure in individual cells in resected, routine-pathology colorectal carcinoma (CRC) patient tissue sections. Chromatin density profiles proved to differ for cells in normal and carcinoma colorectal tissues. In tumour sections, nuclear size and chromatin compaction percentages were significantly different in carcinoma versus normal epithelial and other cells of colorectal tissue. SMLM analysis in nuclei from normal colorectal tissue revealed abrupt changes in chromatin density profiles at the nanoscale, features not detected by conventional widefield microscopy. SMLM for microRNAs relevant for metastasis was achieved in colorectal cancer tissue at the nuclear level. Super-resolution microscopy with quantitative image evaluation algorithms provide powerful tools to analyse chromatin nanostructure and microRNAs of individual cells from normal and tumour tissue at the nanoscale. Our new perspectives improve the differential diagnosis of normal and (metastatically relevant) tumour cells at the single-cell level within the heterogeneity of primary tumours of patients.

Circulating let-7e-5p, miR-106a-5p, miR-28-3p, and miR-542-5p as a Promising microRNA Signature for the Detection of Colorectal Cancer

Simple Summary

The detection of early-stage colorectal cancer increases the chance to prevent tumor progression and death by the disease. Colonoscopy is one sensitive screening test to detect malignant or potentially malignant lesions in the intestines. However, it has some disadvantages, including sedation requirements, increased risk of colon perforation, and bleeding. Circulating microRNAs (miRNAs) in plasma or serum from cancer patients have been investigated and described as potential diagnostic or prognostic markers. We conducted an miRNAs screening test in plasma samples from colorectal cancer patients and subjects without cancer, aiming to identify markers for the early detection of the disease. We identified and validated four miRNAs capable of distinguishing cancer from non-cancer cases. Our non-invasive diagnostic biomarkers presented high performance and are easily applicable to clinical practice.

Abstract

Colorectal cancer (CRC) is a disease with high incidence and mortality. Colonoscopy is a gold standard among tests used for CRC traceability. However, serious complications, such as colon perforation, may occur. Non-invasive diagnostic procedures are an unmet need. We aimed to identify a plasma microRNA (miRNA) signature for CRC detection. Plasma samples were obtained from subjects (n = 109) at different stages of colorectal carcinogenesis. The patients were stratified into a non-cancer (27 healthy volunteers, 17 patients with hyperplastic polyps, 24 with adenomas), and a cancer group (20 CRC and 21 metastatic CRC). miRNAs (381) were screened by TaqMan Low-Density Array. A classifier based on four differentially expressed miRNAs (miR-28-3p, let-7e-5p, miR-106a-5p, and miR-542-5p) was able to discriminate cancer versus non-cancer cases. The overexpression of these miRNAs was confirmed by RT-qPCR, and a cross-study validation step was implemented using eight data series retrieved from Gene Expression Omnibus (GEO). In addition, another external data validation using CRC surgical specimens from The Cancer Genome Atlas (TCGA) was carried out. The predictive model’s performance in the validation set was 76.5% accuracy, 59.4% sensitivity, and 86.8% specificity (area under the curve, AUC = 0.716). The employment of our model in the independent publicly available datasets confirmed a good discrimination performance in five of eight datasets (median AUC = 0.823). Applying this algorithm to the TCGA cohort, we found 99.5% accuracy, 99.7% sensitivity, and 90.9% specificity (AUC = 0.998) when the model was applied to solid colorectal tissues. Overall, we suggest a novel signature of four circulating miRNAs, i.e., miR-28-3p, let-7e-5p, miR-106a-5p, and miR-542-5p, as a predictive tool for the detection of CRC.

Hold on or Cut? Integrin- and MMP-Mediated Cell-Matrix Interactions in the Tumor Microenvironment

The tumor microenvironment (TME) has become the focus of interest in cancer research and treatment. It includes the extracellular matrix (ECM) and ECM-modifying enzymes that are secreted by cancer and neighboring cells. The ECM serves both to anchor the tumor cells embedded in it and as a means of communication between the various cellular and non-cellular components of the TME. The cells of the TME modify their surrounding cancer-characteristic ECM. This in turn provides feedback to them via cellular receptors, thereby regulating, together with cytokines and exosomes, differentiation processes as well as tumor progression and spread. Matrix remodeling is accomplished by altering the repertoire of ECM components and by biophysical changes in stiffness and tension caused by ECM-crosslinking and ECM-degrading enzymes, in particular matrix metalloproteinases (MMPs). These can degrade ECM barriers or, by partial proteolysis, release soluble ECM fragments called matrikines, which influence cells inside and outside the TME. This review examines the changes in the ECM of the TME and the interaction between cells and the ECM, with a particular focus on MMPs.