Intra-tumor heterogeneity of microRNA-92a, microRNA-375 and microRNA-424 in colorectal cancer

Dual role of mesenchymal stem/stromal cells and their cell-free extracellular vesicles in colorectal cancer

Colorectal cancer (CRC) is one of the main causes of cancer-related deaths. However, the surgical control of the CRC progression is difficult, and in most cases, the metastasis leads to cancer-related mortality. Mesenchymal stem/stromal cells (MSCs) with potential translational applications in regenerative medicine have been widely researched for several years. MSCs could affect tumor development through secreting exosomes. The beneficial properties of stem cells are attributed to their cell-cell interactions as well as the secretion of paracrine factors in the tissue microenvironment. For several years, exosomes have been used as a cell-free therapy to regulate the fate of tumor cells in a tumor microenvironment. This review discusses the recent advances and current understanding of assessing MSC-derived exosomes for possible cell-free therapy in CRC.

HNRNPA2B1-Mediated MicroRNA-92a Upregulation and Section Acts as a Promising Noninvasive Diagnostic Biomarker in Colorectal Cancer

MicroRNA-92a (miR-92a) may serve as a novel promising biomarker in multiple cancers, including colorectal cancer (CRC); however, the diagnostic accuracy and the underlying molecular mechanism of miR-92a in CRC is poorly understood. We first carried out meta-analysis and found that serum/plasma miR-92a yield better diagnostic efficacy when compared to stool samples and CRC tissues, and this finding was validated by our independent study through stool sample. Multiple bioinformatics assay indicated that miR-92a expression was positively correlated with heterogeneous nuclear ribonucleoproteins A2/B1 (HNRNPA2B1) expression and closely related with the clinical characteristics of CRC. Experimental evidence showed that knockdown of HNRNPA2B1 could significantly decrease miR-92a expression and secretion in RKO cells. HNRNPA2B1 mediated miR-92a via m6A RNA modification. These findings indicate that HNRNPA2B1-m6A RNA modification-derived MicroRNA-92a upregulation and section from the local CRC acts a candidate noninvasive serum biomarker in colorectal cancer. Our study provides a novel insight into miR-92a mechanisms in relation to both expression and secretion for CRC diagnosis.

The Interaction Between Epigenetic Changes, EMT, and Exosomes in Predicting Metastasis of Colorectal Cancers (CRC)

Worldwide, colorectal cancer (CRC) ranks as the third most common malignancy, and the second most deadly with nearly one million attributable deaths in 2020. Metastatic disease is present in nearly 25% of newly diagnosed CRC, and despite advances in chemotherapy, less than 20% will remain alive at 5 years. Epigenetic change plays a key role in the epithelial-to-mesenchymal transition (EMT), which is a crucial phenotype for metastasis and mainly includes DNA methylation, non-coding RNAs (ncRNAs), and N6-methyladenosine (m6A) RNA, seemingly valuable biomarkers in CRCs. For ncRNAs, there exists a “molecular sponge effect” between long non-coding RNAs (lncRNAs), circular RNAs (circRNAs), and microRNAs (miRNAs). The detection of exosomes is a novel method in CRC monitoring, especially for predicting metastasis. There is a close relationship between exosomes and EMT in CRCs. This review summarizes the close relationship between epigenetic changes and EMT in CRCs and emphasizes the crucial function of exosomes in regulating the EMT process.

The therapeutic potential of stem cell-derived exosomes in the ulcerative colitis and colorectal cancer

BACKGROUND

Mesenchymal stem cells (MSCs) therapy is a novel treatment strategy for cancer and a wide range of diseases with an excessive immune response such as ulcerative colitis (UC), due to its powerful immunomodulatory properties and its capacity for tissue regeneration and repair. One of the promising therapeutic options can focus on MSC-secreted exosomes (MSC-Exo), which have been identified as a type of paracrine interaction. In light of a wide variety of recent experimental studies, the present review aims to seek the recent research advances of therapies based on the MSC-Exo for treating UC and colorectal cancer (CRC).

METHODS

A systematic literature search in MEDLINE, Scopus, and Google Scholar was performed from inception to December 2021 using the terms [("colorectal cancer" OR "bowel cancer" OR "colon cancer" OR "rectal cancer") AND (exosome) AND (stem cell) AND ("inflammatory bowel disease" OR "Crohn's disease" OR "colitis")] in titles and abstracts.

FINDINGS

Exosomes derived from various sources of MSCs, including human umbilical cord-derived MSCs (hUC-MSCs), human adipose-derived MSCs (hAD-MSCs), human bone marrow-derived MSCs (hBM-MSCs), and olfactory ecto-MSCs (OE-MSCs), have shown the protective role against UC and CRC. Exosomes from hUC-MSCs, hBM-MSCs, AD-MSCs, and OE-MSCs have been found to ameliorate the experimental UC through suppressing inflammatory cells including macrophages, Th1/Th17 cells, reducing the expression of proinflammatory cytokines, as well as inducing the anti-inflammatory function of Treg and Th2 cells and enhancing the expression of anti-inflammatory cytokines. In addition, hBM-MSC-Exo and hUC-MSC-Exo containing tumor-suppressive miRs (miR-3940-5p/miR-22-3p/miR-16-5p) have been shown to suppress proliferation, migration, and invasion of CRC cells via regulation of RAP2B/PI3K/AKT signaling pathway and ITGA2/ITGA6.

KEY MESSAGES

The MSC-Exo can exert beneficial effects on UC and CRC through two different mechanisms including modulating immune responses and inducing anti-tumor responses, respectively.

Inhibiting microRNA-424 in bone marrow mesenchymal stem cells-derived exosomes suppresses tumor growth in colorectal cancer by upregulating TGFBR3

OBJECTIVE

MicroRNAs (miRNAs) have been demonstrated to be differently expressed in colorectal cancer (CRC) and were identified as biomarkers and therapeutic targets for CRC. We aimed to identify the effect of microRNA-424 (miR-424) on process of CRC.

METHODS

Exosomes were obtained from bone marrow mesenchymal stem cells (BMSCs). MiR-424, transforming growth factor-β receptor 3 (TGFBR3) vimentin, S100A4, p-Smad1 expression in tissues and cells was measured. After treated with miR-424 inhibitor or TGFBR3 overexpression plasmid, the migration, invasion, cell cycle distribution and apoptosis of Lovo cells and exosomes-transfected Lovo cells were determined. The subcutaneous tumor models were established and the tumor growth was observed. The target relation between miR-424 and TGFBR3 was confirmed.

RESULTS

MiR-424 was upregulated while TGFBR3 was downregulated in CRC tissues. TGFBR3 was targeted by miR-424. Inhibited miR-424 or elevated TGFBR3 upregulated p-Smad1, indicating that TGFBR3 mediated the Smad1 pathway, thus regulating CRC progression. MiR-424 inhibition or TGFBR3 restoration also suppressed migration and invasion of CRC cells, arrested the CRC cells at G0/G1 phase, and promoted CRC cell apoptosis. Moreover, exosomal miR-424 from BMSCs promoted CRC development.

CONCLUSION

Inhibited exosomal miR-424 from BMSCs inhibited malignant behaviors of CRC cells by targeting TGFBR3, thus suppressing the progression of CRC.

A Liquid Biopsy Assay for Noninvasive Identification of Lymph Node Metastases in T1 Colorectal Cancer

BACKGROUND & AIMS

We recently reported use of tissue-based transcriptomic biomarkers (microRNA [miRNA] or messenger RNA [mRNA]) for identification of lymph node metastasis (LNM) in patients with invasive submucosal colorectal cancers (T1 CRC). In this study, we translated our tissue-based biomarkers into a blood-based liquid biopsy assay for noninvasive detection of LNM in patients with high-risk T1 CRC.

METHODS

We analyzed 330 specimens from patients with high-risk T1 CRC, which included 188 serum samples from 2 clinical cohorts-a training cohort (N = 46) and a validation cohort (N = 142)-and matched formalin-fixed paraffin-embedded samples (N = 142). We performed quantitative reverse-transcription polymerase chain reaction, followed by logistic regression analysis, to develop an integrated transcriptomic panel and establish a risk-stratification model combined with clinical risk factors.

RESULTS

We used comprehensive expression profiling of a training cohort of LNM-positive and LMN-negative serum specimens to identify an optimized transcriptomic panel of 4 miRNAs (miR-181b, miR-193b, miR-195, and miR-411) and 5 mRNAs (AMT, forkhead box A1 [FOXA1], polymeric immunoglobulin receptor [PIGR], matrix metalloproteinase 1 [MMP1], and matrix metalloproteinase 9 [MMP9]), which robustly identified patients with LNM (area under the curve [AUC], 0.86; 95% confidence interval [CI], 0.72-0.94). We validated panel performance in an independent validation cohort (AUC, 0.82; 95% CI, 0.74-0.88). Our risk-stratification model was more accurate than the panel and an independent predictor for identification of LNM (AUC, 0.90; univariate: odds ratio [OR], 37.17; 95% CI, 4.48-308.35; P < .001; multivariate: OR, 17.28; 95% CI, 1.82-164.07; P = .013). The model limited potential overtreatment to only 18% of all patients, which is dramatically superior to pathologic features that are currently used (92%).

CONCLUSIONS

A novel risk-stratification model for noninvasive identification of T1 CRC has the potential to avoid unnecessary operations for patients classified as high-risk by conventional risk-classification criteria.

MiR-375: A novel multifunctional regulator

MiR-375, a primitively described beta cell-specific miRNA, is confirmed to function as multi-functional regulator in diverse typical cellular pathways according to the follow-up researches. Based on the existing studies, miR-375 can regulate many functional genes and ectopic expressions of miR-375 are usually associated with pathological changes, and its expression regulation mechanism is mainly related to promoter methylation or circRNA. In this review, the regulatory functions of miR-375 in immunity, such as its relevance with macrophages, T helper cells and autoimmune diseases were briefly discussed. Also, the functions of miR-375 involved in inflammation, development and virus replication were reviewed. Finally, the mechanisms and application prospects of miR-375 in cancers were analyzed. Studies show that the application of miR-375 as therapeutic target and biomarker has a broad developing space in future. We hope this paper can provide reference for its further study.

Intratumor heterogeneity: A new perspective on colorectal cancer research

Colorectal cancers generally consist of multiple subclones. These subclones have their own unique characteristics, resulting in intratumor heterogeneity (ITH). As the discussion of ITH has advanced, a model describing the relationship of ITH to the tumor has gradually emerged. ITH can be divided into two types of intraprimary tumor heterogeneity and intraindividual tumor heterogeneity, the former for further understanding of tumor composition, and the latter for providing more information about evolutionary patterns. With the rapid development of new methods, such as next‐generation, polyguanine region sequencing, and Image detection, researchers may unravel the secrets underlying ITH. The higher the ITH of the tumor, the richer the interaction between the subclones maybe, or the greater the chance of the tumor getting more powerful subclones may be, thus increasing the malignant potential of the tumor. Existing evidence suggests that ITH may increase the ability of tumors to resist treatment and can be used as an independent influence on the prognosis of colorectal cancer. We reviewed 80 recent studies to give researchers a new perspective on colorectal cancer. There is still a limited amount of research in this area. Further study of the relationship between ITH and clinical endpoints may lead to the development of new treatment strategies.

PHLPP2 is regulated by competing endogenous RNA network in pathogenesis of colon cancer

Recently, homologous pleckstrin-homology (PH)-domain leucine-rich-repeat protein phosphatases (PHLPP2) has been reported as a tumor suppressor in colon cancer. This study aimed to unravel the possible involvement of long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) regulating PHLPP2 in colon cancer. Expressions of candidate lncRNAs and miRNAs were verified by the RT-qPCR and Western blot analyses in colon cancer. The roles of candidate genes in colon cancer were investigated in HT-29 cells in vitro and in mouse tumor xenograft model in vivo. PHLPP2, a target of miR-141 and miR-424, was downregulated in colon cancer. PHLPP2 upregulation and miR-141 and miR-424 downregulation suppressed the colon cancer cell proliferation, migration, invasion, and epithelial-mesenchymal transition, and promote cell apoptosis, which also resulted in suppression of tumor metastasis and formation. Furthermore, LINC00402, LINC00461, and SFTA1P were identified as the targets of miR-141 and miR-424 and acted as competitive endogenous RNAs (ceRNAs) of PHLPP2. The upregulation of LINC00402, LINC00461, and SFTA1P was verified to enhance the suppressive effects of PHLPP2 in the pathogenesis of colon cancer. Conjointly, our results demonstrated the suppressive effects of PHLPP2 in colon cancer and proved that LINC00402, LINC00461, and SFTA1P acted as ceRNAs of PHLPP2 by competitive binding to miR-141 and miR-424.

A MicroRNA Signature Associated With Metastasis of T1 Colorectal Cancers to Lymph Nodes

Most T1 colorectal cancers treated by radical surgery can now be cured by endoscopic submucosal dissection. Although 70%-80% of T1 colorectal cancers are classified as high risk, <16% of these patients actually have lymph node metastases. Biomarkers are needed to identify patients with T1 cancers with the highest risk of metastasis, to prevent unnecessary radical surgery. We collected data from The Cancer Genome Atlas and identified 5 microRNAs (MIR32, MIR181B, MIR193B, MIR195, and MIR411) with significant changes in expression in T1 and T2 colorectal cancers with vs without lymph node metastases. Levels of the 5 microRNAs identified patients with lymph node invasion by T1 or T2 cancers with an area under the receiver operating characteristic curve (AUROC) value of 0.84. We validated these findings in 2 cohorts of patients with T1 cancers, using findings from histology as the reference. The 5-microRNA signature identified T1 cancers with lymph node invasion in cohort 1 with an AUROC value of 0.83, and in cohort 2 with an AUROC value of 0.74. When we analyzed biopsy samples from untreated patients, the 5-microRNA signature identified cancers with lymph node metastases with an AUROC value of 0.77. The 5-microRNA therefore identifies high-risk T1 colorectal cancers with a greater degree of accuracy than currently used pathologic features.

Applications of Extracellular RNAs in Oncology

Extracellular RNAs consist of coding and non-coding transcripts released from all cell types, which are involved in multiple cellular processes, predominantly through regulation of gene expression. Recent advances have helped us better understand the functions of these molecules, particularly microRNAs (miRNAs). Numerous pre-clinical and human studies have demonstrated that miRNAs are dysregulated in cancer and contribute to tumorigenesis and metastasis. miRNA profiling has extensively been evaluated as a non-invasive method for cancer diagnosis, prognostication, and assessment of response to cancer therapies. Broader applications for miRNAs in these settings are currently under active development. Investigators have also moved miRNAs into the realm of cancer therapy. miRNA antagonists targeting miRNAs that silence tumor suppressor genes have shown promising pre-clinical activity. Alternatively, miRNA mimics that silence oncogenes are also under active investigation. These miRNA-based cancer therapies are in early development, but represent novel strategies for clinical management of human cancer.

MiRNAs in β-Cell Development, Identity, and Disease

Pancreatic β-cells regulate glucose metabolism by secreting insulin, which in turn stimulates the utilization or storage of the sugar by peripheral tissues. Insulin insufficiency and a prolonged period of insulin resistance are usually the core components of type 2 diabetes (T2D). Although, decreased insulin levels in T2D have long been attributed to a decrease in β-cell function and/or mass, this model has recently been refined with the recognition that a loss of β-cell “identity” and dedifferentiation also contribute to the decline in insulin production. MicroRNAs (miRNAs) are key regulatory molecules that display tissue-specific expression patterns and maintain the differentiated state of somatic cells. During the past few years, great strides have been made in understanding how miRNA circuits impact β-cell identity. Here, we review current knowledge on the role of miRNAs in regulating the acquisition of the β-cell fate during development and in maintaining mature β-cell identity and function during stress situations such as obesity, pregnancy, aging, or diabetes. We also discuss how miRNA function could be harnessed to improve our ability to generate β-cells for replacement therapy for T2D.

Investigating intra-tumor heterogeneity and expression gradients of miR-21, miR-92a and miR-200c and their potential of predicting lymph node metastases in early colorectal cancer

INTRODUCTION

miR-21, miR-92a and miR-200c are regulators of pathways involved in migration, intravasation and metastasis, and their tumor expression levels have been proposed as potential prognostic markers in colorectal cancer (CRC). In two parallel cohorts we examine intra-tumor expression levels in early stage CRC tissue in order to determine intra-tumor heterogeneity, potential systematic intra-tumor expression gradients of the miRNAs and to investigate the association to metastatic disease in early stage CRC.

MATERIAL AND METHODS

Two parallel studies on archived formalin-fixed paraffin-embedded (FFPE) CRC tissue. Intra-tumor and inter-patient variances were analyzed in 9 early metastatic CRCs by measuring expression levels by qRT-PCR on isolated tissue samples from luminal, central and invasive border zones. Associations between miRNA expression levels and early metastasizing tumors was investigated in FFPE tissue from invasive border and central tumor zones from 47 early metastatic CRCs matched with 47 non-metastatic CRCs. Intra-tumor expression gradients were analyzed on both cohorts.

RESULTS

Mean intra-tumor coefficient of variation in the heterogeneity cohort was 38.5% (range: 33.1-49.0%) only slightly less than variation between patients (45.1%, range 37.0-49.5%). We demonstrated systematic expression gradients between tumor zones equal to a 3.23 (p=0.003) and 1.36 (p=0.014) fold lower expression in invasive areas for miR-200c, 1.52 (p<0.001) and 1.27 (p=0.021) fold lower expression in invasive areas for miR-92a. For miR-21 we found a 1.75 (p<0.001) and 1.21 (p=0.064) fold higher expression in invasive areas compared to luminal and central zones, respectively. No significant difference in expression levels between metastatic and non-metastatic tumors was demonstrated, nor a difference in intra-tumor gradients between metastatic and non-metastatic tumors.

CONCLUSION

This study provides evidence for moderate intra-tumor and inter-patient heterogeneities of three well-described potential prognostic markers in CRC. We demonstrate intra-tumor expression gradients indicating a differentiated expression of the target miRNAs between functional tumor zones, but the potential role as markers of early metastatic disease is still not fully clarified.

Stromal Expression of MicroRNA-21 in Advanced Colorectal Cancer Patients with Distant Metastases

BACKGROUND

The aim of this study was to determine the regional heterogeneity and clinicopathological significance of microRNA-21 (miR-21) in advanced colorectal cancer (CRC) patients with distant metastasis.

METHODS

miR-21 expression was investigated by using locked nucleic acid- fluorescence in situ hybridization in the center and periphery of the primary cancer and in distant metastasis from 170 patients with advanced CRC. In addition, α-smooth muscle actin and desmin were evaluated to identify cancer-associated fibroblasts (CAFs) by using immunohistochemistry.

RESULTS

The miR-21 signal was observed in the cancer stroma. The expression of miR-21 (a score of 1-4) in the center and periphery of the primary cancer and in distant metastasis was observed in specimens from 133 (78.2%), 105 (61.8%), and 91 (53.5%) patients, respectively. miR-21 expression was heterogeneous in advanced CRC. Discordance between miR-21 expression in the center of the primary cancer and either the periphery of the primary cancer or distant metastasis was 31.7% or 44.7%, respectively. miR-21 stromal expression in the periphery of the primary cancer was significantly associated with a better prognosis (p=.004). miR-21 expression was significantly associated with CAFs in the center of the primary cancer (p=.001) and distant metastases (p=.041).

CONCLUSIONS

miR-21 expression is observed in cancer stroma related to the CAF quantity and frequently presents regional heterogeneity in CRC. Our findings indicate that the role of miR-21 in predicting prognosis may be controversial but provide a new perspective of miR-21 level measurement in cancer specimens.

Nephroangiography in Wegener's granulumatosis. A comparison with panarteritis nodosa

Three cases of Wegener's granulomatosis with a classical course are described, 2 of which with fatal outcome in spite of immuno-suppressive therapy. Nephroangiography was performed during the oliguric or anuric phase. The appearances were similar to those encountered in glomerulonephritis and were compared with those in three cases of panarteritis nodosa. Two of these represented the classical form with intrarenal arterial aneurysms; the third was a case of the microscopic type presenting blurred intrarenal arteries with lumen variations and occlusions. These observations support the opinion that Wegener's granulomatosis nodosa are different diseases. Nephroangiography seems to be of value in their differentiation.