miR-491 inhibits BGC-823 cell migration via targeting HMGA2

HMGA2 regulation by miRNAs in cancer: affecting cancer hallmarks and therapy response

High mobility group A 2 (HMGA2) is a protein that modulates the structure of chromatin in the nucleus. Importantly, aberrant expression of HMGA2 occurs during carcinogenesis, and this protein is an upstream mediator of cancer hallmarks including evasion of apoptosis, proliferation, invasion, metastasis, and therapy resistance. HMGA2 targets critical signaling pathways such as Wnt/β-catenin and mTOR in cancer cells. Therefore, suppression of HMGA2 function notably decreases cancer progression and improves outcome in patients. As HMGA2 is mainly oncogenic, targeting expression by non-coding RNAs (ncRNAs) is crucial to take into consideration since it affects HMGA2 function. MicroRNAs (miRNAs) belong to ncRNAs and are master regulators of vital cell processes, which affect all aspects of cancer hallmarks. Long ncRNAs (lncRNAs) and circular RNAs (circRNAs), other members of ncRNAs, are upstream mediators of miRNAs. The current review intends to discuss the importance of the miRNA/HMGA2 axis in modulation of various types of cancer, and mentions lncRNAs and circRNAs, which regulate this axis as upstream mediators. Finally, we discuss the effect of miRNAs and HMGA2 interactions on the response of cancer cells to therapy. Regarding the critical role of HMGA2 in regulation of critical signaling pathways in cancer cells, and considering the confirmed interaction between HMGA2 and one of the master regulators of cancer, miRNAs, targeting miRNA/HMGA2 axis in cancer therapy is promising and this could be the subject of future clinical trial experiments.

Extracellular Vesicles' Genetic Cargo as Noninvasive Biomarkers in Cancer: A Pilot Study Using ExoGAG Technology

The two most developed biomarkers in liquid biopsy (LB)-circulating tumor cells and circulating tumor DNA-have been joined by the analysis of extracellular vesicles (EVs). EVs are lipid-bilayer enclosed structures released by all cell types containing a variety of molecules, including DNA, mRNA and miRNA. However, fast, efficient and a high degree of purity isolation technologies are necessary for their clinical routine implementation. In this work, the use of ExoGAG, a new easy-to-use EV isolation technology, was validated for the isolation of EVs from plasma and urine samples. After demonstrating its efficiency, an analysis of the genetic material contained in the EVs was carried out. Firstly, the sensitivity of the detection of point mutations in DNA from plasma EVs isolated by ExoGAG was analyzed. Then, a pilot study of mRNA expression using the nCounter NanoString platform in EV-mRNA from a healthy donor, a benign prostate hyperplasia patient and metastatic prostate cancer patient plasma and urine samples was performed, identifying the prostate cancer pathway as one of the main ones. This work provides evidence for the value of using ExoGAG for the isolation of EVs from plasma and urine samples, enabling downstream applications of the analysis of their genetic cargo.

FOCAD/miR-491-5p, downregulated by EGR1, function as tumor suppressor by inhibiting the proliferation and migration of gastric cancer cells

Gastric cancer is a common malignant tumor in China; however, its carcinogenesis remains unknown. Focadhesin (FOCAD) is a tumor suppressor gene in gliomas, its expression, role, and mechanism in gastric cancer have not been defined. The aim of the present study was to explore the expression pattern of FOCAD in human normal tissues and cancer tissues and elucidate the role and regulatory mechanism of Early Growth Response 1 (EGR1) in FOCAD and its intron, miR-491-5p, in gastric cancer. Immuno histochemical staining revealed that FOCAD is widely and highly expressed in normal gastric mucosa, but is absent in gastric cancer tissue. Based on an association analysis FOCAD expression was found to be negatively associated with lymph node metastasis (P = 0.004); higher FOCAD levels were associated with longer survival in patients with gastric cancer (P = 0.001). MTT, colony, Transwell chamber, and flow cytometry assays revealed that siFOCAD promoted cell proliferation, growth, and migration, and inhibited apoptosis. Furthermore, bioinformatic analysis, Fluorescence reporter gene and chromatin immunoprecipitation analyses confirmed that EGR1 binds to the promoter and negatively regulates FOCAD and miR-491-5p at the transcriptional level. The overexpression of EGR1 was also found to promote cell proliferation, growth, and migration, and inhibit apoptosis. Overall, FOCAD is specifically overexpressed in the gastric mucosa and is significantly downregulated in gastric cancer. To our knowledge, this is the first study to demonstrate that FOCAD is a tumor suppressor, higher FOCAD levels might be a better prognostic marker of gastric cancer, and FOCAD/miR-491-5p may be negatively regulated by EGR1.

The Tumor Suppressor Roles and Mechanisms of MiR-491 in Human Cancers

MicroRNAs (miRNAs) are short non-coding RNAs that bind to the 3' untranslated region (3'' UTR) of target mRNAs to control gene expression post-transcriptionally. Recent indications have highlighted their important roles in a variety of pathophysiological conditions as well as human malignancies. Dysregulated miRNAs act as tumor suppressor genes or oncogenes in a variety of cancers. MiR-491 has been shown to have a major effect on tumorigenesis in multiple malignancies through binding to specific genes and signaling cascades, thereby preventing cancer progression. This review provides an overview of miR-491 expression in regulatory mechanisms and biological procedures of tumor cells, as well as the prospective possible treatment effects of various types of human cancers.

Low Expression of miR-491-3p Is Correlated with Lymph Node Metastasis in Gastric Cancer

Objective

MiR-491-3p, as a tumor suppressor miRNA, was found decreased in many solid tissues. In this study, we aim to investigate miR-491-3p expression in gastric cancer with or without lymph node metastasis (LNM).

Methods

GSE173215 dataset from Gene Expression Omnibus (GEO) was used to measure miRNA expression from tissue samples of gastric cancer patients. Moreover, gastric tumor tissues (non-LNM: n = 78; LNM: n = 68) were obtained to detect the miR-491-3p expression. Receiver operating characteristic (ROC) curve and Kaplan–Meier (KM) survival analysis, as well as Cox regression analysis, were performed to reveal the role of miR-491-3p in diagnosis and prognosis of gastric cancer.

Results

According to GSE173215 datasets (t = −11.25, adjust P value = 1.30E-06) and our clinical results (0.390 ± 0.193 vs. 0.562 ± 0.166, P < 0.005), the gastric cancer patients with LNM showed lower miR-491-3p expression than those without LNM, demonstrating a high diagnostic efficiency (sensitivity: 74.36%; specificity: 69.12%). In addition, both LNM and low miR-491-3p expression were correlated with the poor prognosis of gastric cancer. Furthermore, the LNM patient with low expression of miR-491-3p had the worse prognosis, but the non-LNM patient with high expression of miR-491-3p had the best prognosis. MiR-491-3p expression (HR = 0.003, 95%CI: 3.35E-04∼0.028) and LNM (HR = 2.326, 95%CI: 1.046∼5.173) were independent risk factors for gastric cancer.

Conclusion

Downregulated miR-491-3p expression was found in gastric cancer, being a high diagnostic efficiency and an independent risk factor for gastric cancer, especially in those having LNM.

miR-181a-2-3p Stimulates Gastric Cancer Progression via Targeting MYLK

Background: The abnormal expression of miRNAs facilitates tumorigenesis and development. miR-181a-2-3p is up-regulated in various cancers, yet its mechanism in gastric cancer (GC) remains elusive.

Objective: To understand mechanism of miR-181a-2-3p stimulating GC cell progression via targeting Myosin Light Chain Kinase (MYLK) expression.

Methods: Downstream genes of miRNA of interest were predicted in TargetScan and miRTarBase. qRT-PCR and western blot were applied to assess miR-181a-2-3p and MYLK expression in GC cells and normal cells. Dual-luciferase and RIP assays were completed to assess binding of miR-181a-2-3p and MYLK. Cell Counting Kit-8 (CCK-8) assay was conducted for detecting viability of AGS and SNU-1 cells, while Transwell tested migratory and invasive abilities of cells. Nude mouse transplantation tumor experiment was performed to assay tumor growth in vivo.

Results: miR-181a-2-3p was notably increased in human GC cell lines, while MYLK was remarkably down-regulated. RIP and dual-luciferase assay disclosed that miR-181a-2-3p targeted MYLK and repressed MYLK. Forced miR-181a-2-3p expression fostered GC cell proliferation, invasion, migration, and fostered tumor growth in vivo. Promoting effect of miR-181a-2-3p on GC cells was reversed when miR-181a-2-3p and MYLK were simultaneously overexpressed.

Conclusion: miR-181a-2-3p facilitated GC cell progression by targeting MYLK, and it may be a pivotal prognostic biomarker in investigating molecular mechanism of GC.

Overexpression of hsa_circ_0008274 inhibited the progression of lung adenocarcinoma by regulating HMGA2 via sponging miR-578

Background

Circular RNAs (circRNAs) had been identified as a non‐coding RNA associated with many types of cancer in recent years. However, the involvement of hsa_circ_0008274 in lung adenocarcinoma (LUAD) has not been explored. The aim of our research is to explore the biological mechanism and function of hsa_circ_0008274 in LUAD.

Methods

The hsa_circ_0008274, miR‐578, and high mobility group AT‐Hook 2 (HMGA2) mRNA expression levels were detected via qRT‐PCR. Cell Counting Kit‐8 (CCK‐8) Transwell assay and wound healing assay were performed to measure the cell proliferation, invasion, and migration ability. Luciferase reporter and Western blotting experiments were performed to characterize the competing endogenous RNA (ceRNA) mechanism of hsa_circ_0008274.

Results

Our findings determined that the expression of hsa_circ_0008274 in LUAD was significantly decreased. Cell experiments showed that overexpressed hsa_circ_0008274 could reduce the proliferation and invasion ability of LUAD cells. Moreover, miRNA‐578 could identify as a miRNA sponge of hsa_circ_0008274. Overexpressed hsa_circ_0008274 reduced the proliferation and invasion of LUAD cells caused by miR‐578 mimics. Increasing the expression of miR‐578 can aggravate the proliferation and invasion of LUAD cells and block the inhibition of proliferation and invasion of LUAD cells mediated by overexpressed hsa_circ_0008274. Subsequent data indicate that HMGA2 of the tumor‐promoting gene is the target gene of miR‐578. The upregulation of HMGA2 partially reversed the tumor inhibitory effect of LUAD cells induced by overexpressed hsa_circ_0008274 or miR‐578 mimics.

Conclusions

In summary, our data show that the overexpression of hsa_circ_0008274 repressed the proliferation and invasion of LUAD through downregulating miR‐578 and activating HMGA2.

circ‑0000212 promotes cell proliferation of colorectal cancer by sponging miR‑491 and modulating FOXP4 expression

Colorectal cancer (CRC) is a lethal and common malignancy worldwide. Non-coding (nc)RNAs have been shown to modulate tumor progression in several types of cancer. The present study aimed to investigate the role of hsa_circ_0000212 in CRC, as a sponge of microRNA (miR)-491. The expression levels of miR-491 and forkhead box P4 (FOXP4) were analyzed using data from The Cancer Genome Atlas. The association between miR-491 and FOXP4 and the clinicopathological characteristics were also analyzed. A novel circular (circ)RNA, hsa_circ_0000212, was found to sponge miR-491 based on bioinformatics analysis. The potential binding site between miR-491 and FOXP4 or circ-0000212 was validated using luciferase and RNA immunoprecipitation assays. The expression levels and distribution of circ-0000212 was also determined. Cell Counting Kit-8 and colony formation assays were performed to determine the role of miR-491 or circ-0000212 on the proliferation of the CRC cells. Decreased miR-491 or increased FOXP4 expression levels were associated with the pathological stage in patients with CRC. In addition, miR-491 inhibited cell proliferation by targeting FOXP4. circ-0000212 was increased in CRC tissues and was predominantly localized in the cytoplasm. Furthermore, circ-0000212 augmented viability of the CRC cells by sponging miR-491 and modulating FOXP4. In conclusion, circ-0000212 may serve as a novel tumor-promoter and drug target in CRC.

HMGA2 as a Critical Regulator in Cancer Development

The high mobility group protein 2 (HMGA2) regulates gene expression by binding to AT-rich regions of DNA. Akin to other DNA architectural proteins, HMGA2 is highly expressed in embryonic stem cells during embryogenesis, while its expression is more limited at later stages of development and in adulthood. Importantly, HMGA2 is re-expressed in nearly all human malignancies, where it promotes tumorigenesis by multiple mechanisms. HMGA2 increases cancer cell proliferation by promoting cell cycle entry and inhibition of apoptosis. In addition, HMGA2 influences different DNA repair mechanisms and promotes epithelial-to-mesenchymal transition by activating signaling via the MAPK/ERK, TGFβ/Smad, PI3K/AKT/mTOR, NFkB, and STAT3 pathways. Moreover, HMGA2 supports a cancer stem cell phenotype and renders cancer cells resistant to chemotherapeutic agents. In this review, we discuss these oncogenic roles of HMGA2 in different types of cancers and propose that HMGA2 may be used for cancer diagnostic, prognostic, and therapeutic purposes.

Role of microRNAs in Pressure Ulcer Immune Response, Pathogenesis, and Treatment

Pressure ulcers are preventable, yet highly prevalent, chronic wounds that have significant patient morbidity and high healthcare costs. Like other chronic wounds, they are characterized by impaired wound healing due to dysregulated immune processes. This review will highlight key biochemical pathways in the pathogenesis of pressure injury and how this signaling leads to impaired wound healing. This review is the first to comprehensively describe the current literature on microRNA (miRNA, miR) regulation of pressure ulcer pathophysiology.

RNA Binding Proteins as Drivers and Therapeutic Target Candidates in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinomas (PDAC) belong to the most frequent and most deadly malignancies in the western world. Mutations in KRAS and TP53 along with some other frequent polymorphisms occur almost universally and are likely to be responsible for tumor initiation. However, these mutations cannot explain the heterogeneity in therapeutic responses observed in PDAC patients, which limits efficiency of current therapeutic strategies. Instead, recent classifications of PDAC tumor samples are based on transcriptomics data and thus include information about epigenetic, transcriptomic, and post-transcriptomic deregulations. RNA binding proteins (RBPs) are important post-transcriptional regulators involved in every aspect of the RNA life cycle and thus considerably influence the transcriptome. In this study, we systematically investigated deregulated expression, prognostic value, and essentiality reported for RBPs in PDAC or PDAC cancer models using publicly available data. We identified 44 RBPs with suggested oncogenic potential. These include various proteins, e.g., IGF2 mRNA binding proteins (IGF2BPs), with reported tumor-promoting roles. We further characterized these RBPs and found common patterns regarding their expression, interaction, and regulation by microRNAs. These analyses suggest four prime candidate oncogenic RBPs with partially validated target potential: APOBEC1, IGF2BP1 and 3, and OASL.

High Mobility Group A (HMGA): Chromatin Nodes Controlled by a Knotty miRNA Network

High mobility group A (HMGA) proteins are oncofoetal chromatin architectural factors that are widely involved in regulating gene expression. These proteins are unique, because they are highly expressed in embryonic and cancer cells, where they play a relevant role in cell proliferation, stemness, and the acquisition of aggressive tumour traits, i.e., motility, invasiveness, and metastatic properties. The HMGA protein expression levels and activities are controlled by a connected set of events at the transcriptional, post-transcriptional, and post-translational levels. In fact, microRNA (miRNA)-mediated RNA stability is the most-studied mechanism of HMGA protein expression modulation. In this review, we contribute to a comprehensive overview of HMGA-targeting miRNAs; we provide detailed information regarding HMGA gene structural organization and a comprehensive evaluation and description of HMGA-targeting miRNAs, while focusing on those that are widely involved in HMGA regulation; and, we aim to offer insights into HMGA-miRNA mutual cross-talk from a functional and cancer-related perspective, highlighting possible clinical implications.