miR-512-5p suppresses tumor growth by targeting hTERT in telomerase positive head and neck squamous cell carcinoma in vitro and in vivo

MicroRNAs role in telomere length maintenance and telomerase activity in tumor cells

MiRNAs, a class of non-coding RNA molecules, have emerged as critical modulators of telomere length and telomerase activity by finely tuning the expression of target genes (and not gene targets) within signaling pathways involved in telomere homeostasis. The primary objective of this systematic review was to compile and synthesize the existing body of knowledge on the role, association, and involvement of miRNAs in telomere length. Additionally, the review explored the regulation, function, and activation mechanism of the human telomerase reverse transcriptase (hTERT) gene and telomerase activity in tumor cells. A comprehensive analysis of 47 selected articles revealed 40 distinct miRNAs involved in these processes. These miRNAs were shown to exert their function, in both clinical cases and cell line models, either directly or indirectly, regulating hTERT and telomerase activity through distinct molecular mechanisms. The regulatory roles of these miRNAs significantly affected major cancer phenotypes, with outcomes largely dependent on the tissue type and the cellular actions within the tumor cells, whereby they functioned as oncogenes or tumor suppressors. These findings strongly support the pivotal role of miRNAs in modulating telomere length and telomerase activity, thereby contributing to the intricate and complex regulation of telomere homeostasis in tumor cells. Moreover, they emphasize the potential of targeting miRNAs and key regulatory genes as therapeutic strategies to disrupt cancer cell growth and promote senescence, offering promising avenues for novel cancer treatments.

Matrix Metalloproteinases Inhibitors in Cancer Treatment: An Updated Review (2013-2023)

Matrix metalloproteinases (MMPs) are identifiable members of proteolytic enzymes that can degrade a wide range of proteins in the extracellular matrix (ECM). MMPs can be categorized into six groups based on their substrate specificity and structural differences: collagenases, gelatinases, stromelysins, matrilysins, metalloelastase, and membrane-type MMPs. MMPs have been linked to a wide variety of biological processes, such as cell transformation and carcinogenesis. Over time, MMPs have been evaluated for their role in cancer progression, migration, and metastasis. Accordingly, various MMPs have become attractive therapeutic targets for anticancer drug development. The first generations of broad-spectrum MMP inhibitors displayed effective inhibitory activities but failed in clinical trials due to poor selectivity. Thanks to the evolution of X-ray crystallography, NMR analysis, and homology modeling studies, it has been possible to characterize the active sites of various MMPs and, consequently, to develop more selective, second-generation MMP inhibitors. In this review, we summarize the computational and synthesis approaches used in the development of MMP inhibitors and their evaluation as potential anticancer agents.

Circ_0000520 interacts with miR-512-5p to upregulate KIAA0100 to promote malignant behaviors in lung cancer

BACKGROUND

CircRNAs function as pivotal molecules to regulate the malignant development of lung cancer. This study was designed to research the functional role and how it acted in lung cancer progression.

METHODS

Circ_0000520, microRNA-512-5p (miR-512-5p) and Breast cancer-overexpressed gene 1 (KIAA0100) levels were measured through reverse transcription-quantitative polymerase chain reaction assay. Cell Counting Kit-8 assay and EdU assay were used to examine cell proliferation. Cell cycle and apoptosis were evaluated via flow cytometry. The protein levels were determined using western blot. Cell migration and invasion were assessed by wound healing assay and transwell assay. The circ_0000520 function in vivo was explored by tumor xenograft assay. The molecular interaction was analyzed via Dual-luciferase reporter assay.

RESULTS

Circ_0000520 was obviously upregulated in lung cancer tissues and cells. Silence of circ_0000520 inhibited proliferation, cell cycle progression, migration, invasion and angiogenesis but promoted cell apoptosis. Circ_0000520 downregulation reduced tumor growth of lung cancer in vivo. Circ_0000520 served as a miR-512-5p sponge. The oncogenic function of circ_0000520 was partly achieved by sponging miR-512-5p in lung cancer. KIAA0100 was a target of miR-512-5p and miR-512-5p inhibited the malignant behaviors of lung cancer cells via downregulating KIAA0100. Circ_0000520 targeted miR-512-5p to regulate the level of KIAA0100.

CONCLUSION

All these data demonstrated that circ_0000520 was able to drive the progression of lung cancer via the mediation of miR-512-5p/KIAA0100 axis. Circ_0000520 might be a potential biomarker for lung cancer.

A short review on cancer therapeutics

Cancer as a disease has been a remarkable scourge and over the past years, advances have been made in understanding the molecular basis of carcinogenesis and combating this disease. The common traits exhibited by cancer have been individually studied to figure out its mode of action and its mechanism of survival even in the most austere conditions. The various hallmarks noted so far have been effectively studied and different therapies revolving around each hallmark are still being studied in order to find the most appropriate treatment for the different types of cancer in existence. Emerging therapies have been able to elucidate the mechanism of receptor blockage which facilitate the ability of cancer to proliferate as well as evade tumor suppressors, prevent cell death, support replicative immortality, escape immune destruction, stimulate angiogenesis, reduce cellular energetics as well as metabolism and prevent the destruction of the immune system. This life-threatening disease should be tackled aggressively with a combined therapy that involves two or more hallmarks of cancer and adverse effects of each therapy should also be considered.

Molecular Mechanisms of Immunosenescene and Inflammaging: Relevance to the Immunopathogenesis and Treatment of Multiple Sclerosis

Aging is characterized, amongst other features, by a complex process of cellular senescence involving both innate and adaptive immunity, called immunosenescence and associated to inflammaging, a low-grade chronic inflammation. Both processes fuel each other and partially explain increasing incidence of cancers, infections, age-related autoimmunity, and vascular disease as well as a reduced response to vaccination. Multiple sclerosis (MS) is a lifelong disease, for which considerable progress in disease-modifying therapies (DMTs) and management has improved long-term survival. However, disability progression, increasing with age and disease duration, remains. Neurologists are now involved in caring for elderly MS patients, with increasing comorbidities. Aging of the immune system therefore has relevant implications for MS pathogenesis, response to DMTs and the risks mediated by these treatments. We propose to review current evidence regarding markers and molecular mechanisms of immunosenescence and their relevance to understanding MS pathogenesis. We will focus on age-related changes in the innate and adaptive immune system in MS and other auto-immune diseases, such as systemic lupus erythematosus and rheumatoid arthritis. The consequences of these immune changes on MS pathology, in interaction with the intrinsic aging process of central nervous system resident cells will be discussed. Finally, the impact of immunosenescence on disease evolution and on the safety and efficacy of current DMTs will be presented.

Diagnosis and staging of HCV associated fibrosis, cirrhosis and hepatocellular carcinoma with target identification for miR-650, 552-3p, 676-3p, 512-5p and 147b

BACKGROUND: Chronic HCV infection progresses to fibrosis, cirrhosis and hepatocellular carcinoma (HCC). The latter represents the third most common cause for cancer mortality. Currently, there is no reliable non-invasive biomarker for diagnosis of HCV mediated disorders. OBJECTIVE: Profiling expression signature for circulatory miRNAs in the plasma of 167 Egyptian patients (40 healthy, 48 HCV fibrotic, 39 HCV cirrhotic and 40 HCV-HCC cases). METHODS: QRTPCR was used to quantify expression signature for circulatory miRNAs. RESULTS: MiR-676 and miR-650 were powerful in discriminating cirrhotic and late fibrosis from HCC. MiR-650 could distinguish mild (f0-f1) and advanced (f2-f3) fibrosis from HCC cases. MiR-650 and miR-147b could distinguish early fibrosis from healthy controls meanwhile miR-676 and miR-147b could effectively distinguish between mild chronic and (f1-f3) cases from healthy individuals. All studied miRNAs, except miR-512, can differentiate between (f0-f3) cases and healthy controls. Multivariate logistic regression revealed three potential miRNA panels for effective differentiation of HCC, cirrhotic and chronic liver cases. MiR-676-3p and miR-512-5p were significantly correlated in (f1-f3) fibrosis meanwhile miR-676 and miR-512 could differentiate between cirrhosis and (f0-f3) cases. Both miR-650 and miR-512-5p were positively correlated in the cirrhotic group and in (f0-f4) group. Putative targets for investigated miRNAs were also determined. CONCLUSIONS: Investigated miRNAs could assist in staging and diagnosis of HCV associated disorders.

Circ_0000215 Exerts Oncogenic Function in Nasopharyngeal Carcinoma by Targeting miR-512-5p

Background: Increasing circular RNAs (circRNAs) are reported to participate in cancer progression. Nonetheless, the role of circRNAs in nasopharyngeal carcinoma (NPC) has not been fully clarified. This work is aimed to probe the role of circ_0000215 in NPC.

Methods: Circ_0000215 expression in NPC tissues and cell lines was examined by quantitative real-time polymerase chain reaction (qRT-PCR). Cell counting kit-8 (CCK-8) assay, 5-bromo-2′-deoxyuridine (BrdU) assay, scratch healing assay and Transwell experiment were executed to investigate the regulatory function of circ_0000215 on the proliferation, migration and invasion of NPC cells. RNA immunoprecipitation (RIP), pull-down and dual-luciferase reporter experiments were utilized to determine the binding relationship between circ_0000215 and miR-512-5p, and between miR-512-5p and phosphoinositide-3-kinase regulatory subunit 1 (PIK3R1) 3′UTR. The effects of circ_0000215 on NPC growth and metastasis in vivo were examined with nude mice model. Western blot was applied to detect the regulatory effects of circ_0000215 and miR-512-5p on PIK3R1 expression.

Results: Circ_0000215 was overexpressed in NPC tissues and cell lines. The functional experiments confirmed that knockdown of circ_0000215 impeded the growth and metastasis of NPC cells in vitro and in vivo. Additionally, circ_0000215 could also work as a molecular sponge to repress miR-512-5p expression. PIK3R1 was validated as a target gene of miR-512-5p, and circ_0000215 could increase the expression level of PIK3R1 in NPC cells via suppressing miR-512-5p.

Conclusion: Circ_0000215 is overexpressed in NPC and exerts oncogenic effects in NPC through regulating miR-512-5p/PIK3R1 axis.

Novel cytoplasmic lncRNA IKBKBAS promotes lung adenocarcinoma metastasis by upregulating IKKβ and consequential activation of NF-κB signaling pathway

NF-κB signaling pathway is a critical link between inflammation and cancer. Emerging evidence suggested that long non-coding RNAs (lncRNAs) were involved in dysregulation of NF-κB. Herein, we reported a novel lncRNA IKBKBAS that activated NF-κB in lung adenocarcinoma (LUAD) by upregulating IKKβ, a key member of NF-κB signaling pathway, thereby promoting the metastasis of LUAD both in vitro and in vivo. The upregulated IKBKBAS functioned as a competing endogenous RNA (ceRNA) via competing with IKKβ mRNA for binding miR-4741, consequently leading to upregulation and activation of IKKβ, and ultimately activation of NF-κB. The abnormally elevated IKBKBAS in LUAD was mainly resulted from the extremely decrease of miR-512-5p that targeting IKBKBAS. Furthermore, we identified a positive feedback loop between NF-κB and IKBKBAS, in which NF-κB activation induced by overexpression of IKBKBAS could promote the transcription of IKBKBAS by binding the κB sites within IKBKBAS promoter. Our studies revealed that IKBKBAS was involved in the activation of NF-κB signaling by upregulating the expression of IKKβ, which made it serve as a potential novel target for therapies to LUAD.

The Regulatory Mechanism of Feeding a Diet High in Rice Grain on the Growth and microRNA Expression Profiles of the Spleen, Taking Goats as an Artiodactyl Model

Several researchers have testified that feeding with diets high in rice grain induces subacute ruminal acidosis and increases the risk of gastrointestinal inflammation. However, whether diets high in rice grain affect spleen growth and related molecular events remains unknown. Therefore, the present study was conducted to investigate the effects of feeding a high-concentrate (HC) diet based on rice on the growth and microRNA expression profiles in goat spleen. Sixteen Liuyang black goats were used as an artiodactyl model and fed an HC diet for five weeks. Visceral organ weight, LPS (lipopolysaccharide) concentration in the liver and spleen, and microRNA expression were analyzed. The results showed that feeding an HC diet increased the heart and spleen indexes and decreased the liver LPS concentration (p < 0.05). In total, 596 microRNAs were identified, and twenty-one of them were differentially expressed in the spleens of goats fed with the HC diet. Specifically, several microRNAs (miR-107, miR-512, miR-51b, miR-191, miR-296, miR-326, miR-6123 and miR-433) were upregulated. Meanwhile, miR-30b, miR-30d, miR-1468, miR-502a, miR-145, miR-139, miR-2284f, miR-101 and miR-92a were downregulated. Additionally, their target gene CPPED1, CDK6, CCNT1 and CASP7 expressions were inhibited (p < 0.05). These results indicated that the HC diet promoted the growth of the heart and spleen. The HC diet also regulated the expression of miR-326, miR-512-3p, miR-30b, miR-30d, miR-502a and their target genes (CPPED1, CDK6 and CCNT1) related to the enhancement of splenocyte proliferation. The HC diet also modulated the expression of miR-15b-5p, miR-1468 and miR-92a, related to the suppression of splenocyte apoptosis.

Exosomes derived from microRNA-512-5p-transfected bone mesenchymal stem cells inhibit glioblastoma progression by targeting JAG1

In this study, we demonstrate that bone mesenchymal stem cell (BMSC)-derived exosomes alter tumor phenotypes by delivering miR-512-5p. miR-512-5p was downregulated in glioblastoma tissues and cells, and Jagged 1 (JAG1) was the target gene of miR-512-5p. We clarified the expression patterns of miR-512-5p and JAG1 along with their interactions in glioblastoma. Additionally, we observed that BMSC-derived exosomes could contain and transport miR-512-5p to glioblastoma cells in vitro. BMSC-derived exosomal miR-512-5p inhibited glioblastoma cell proliferation and induced cell cycle arrest by suppressing JAG1 expression. In vivo assays validated the in vitro findings, with BMSC-exosomal miR-512-5p inhibiting glioblastoma growth and prolonging survival in mice. These results suggest that BMSC-derived exosomes transport miR-512-5p into glioblastoma and slow its progression by targeting JAG1. This study reveals a new molecular mechanism for glioblastoma treatment and validates miRNA packaging into exosomes for glioblastoma cell communication.

Telomerase Regulation: A Role for Epigenetics

Simple Summary

Maintenance of telomeres is a fundamental step in human carcinogenesis and is primarily regulated by telomerase and the human telomerase reverse transcriptase gene (TERT). Improved understanding of the transcriptional control of this gene may provide potential therapeutic targets. Epigenetic modifications are a prominent mechanism to control telomerase activity and regulation of the TERT gene. TERT-targeting miRNAs have been widely studied and their function explained through pre-clinical in vivo model-based validation studies. Further, histone deacetylase inhibitors are now in pre and early clinical trials with significant clinical success. Importantly, TERT downregulation through epigenetic modifications including TERT promoter methylation, histone deacetylase inhibitors, and miRNA activity might contribute to clinical study design. This review provides an overview of the epigenetic mechanisms involved in the regulation of TERT expression and telomerase activity.

Abstract

Telomerase was first described by Greider and Blackburn in 1984, a discovery ultimately recognized by the Nobel Prize committee in 2009. The three decades following on from its discovery have been accompanied by an increased understanding of the fundamental mechanisms of telomerase activity, and its role in telomere biology. Telomerase has a clearly defined role in telomere length maintenance and an established influence on DNA replication, differentiation, survival, development, apoptosis, tumorigenesis, and a further role in therapeutic resistance in human stem and cancer cells including those of breast and cervical origin. TERT encodes the catalytic subunit and rate-limiting factor for telomerase enzyme activity. The mechanisms of activation or silencing of TERT remain open to debate across somatic, cancer, and stem cells. Promoter mutations upstream of TERT may promote dysregulated telomerase activation in tumour cells but additional factors including epigenetic, transcriptional and posttranscriptional modifications also have a role to play. Previous systematic analysis indicated methylation and mutation of the TERT promoter in 53% and 31%, respectively, of TERT expressing cancer cell lines supporting the concept of a key role for epigenetic alteration associated with TERT dysregulation and cellular transformation. Epigenetic regulators including DNA methylation, histone modification, and non-coding RNAs are now emerging as drivers in the regulation of telomeres and telomerase activity. Epigenetic regulation may be responsible for reversible silencing of TERT in several biological processes including development and differentiation, and increased TERT expression in cancers. Understanding the epigenetic mechanisms behind telomerase regulation holds important prospects for cancer treatment, diagnosis and prognosis. This review will focus on the role of epigenetics in telomerase regulation.

Development and validation of a novel circular RNA as an independent prognostic factor in acute myeloid leukemia

BACKGROUND

Although there are many clinical and molecular biomarkers in acute myeloid leukemia (AML), the novel and reliable biomarkers are still required to predict the overall survival at the time of disease diagnosis.

METHODS

In order to identify independent predictors, we firstly selected 60 cytogenetically normal AML (CN-AML) patients using the propensity score analysis to balance the confounders and performed circular RNA (circRNA) sequencing. Next, one outcome related to circRNA was selected and validated in the independent cohort of 218 CN-AML patients. We then constructed circRNA-miRNA-mRNA regulated network and performed cellular metabolomic analysis to decipher the underlying biological insights.

RESULTS

We identified 308 circRNAs as independent candidate predictors of overall survival. Hsa_circ_0075451 expression was validated as an independent predictor with a weak predictive ability for overall survival. The regulated network of this circular RNA indicated 84 hub genes that appear to be regulated by 10 miRNAs sponged by hsa_circ_0075451. The regulatory axis of hsa_circ_0075451 -| miR-330-5p/miR-326 -| PRDM16 was validated by the dual luciferase report assay, fluorescence in situ hybridization, and ShRNA interference assay.

CONCLUSIONS

Our data demonstrates that hsa_circ_0075451 expression may independently contribute to the poor prognosis of AML and present a novel therapeutic target.

Modulation of telomerase expression and function by miRNAs: Anti-cancer potential

Telomerase is a nucleoprotein reverse transcriptase that maintains the telomere, a protective structure at the ends of the chromosome, and is active in cancer cells, stem cells, and fetal cells. Telomerase immortalizes cancer cells and induces unlimited cell division by preventing telomere shortening. Immortalized cancer cells have unlimited proliferative potential due to telomerase activity that causes tumorigenesis and malignancy. Therefore, telomerase can be a lucrative anti-cancer target. The regulation of catalytic subunit of telomerase (TERT) determines the extent of telomerase activity. miRNAs, as an endogenous regulator of gene expression, can control telomerase activity by targeting TERT mRNA. miRNAs that have a decreasing effect on TERT translation mediate modulation of telomerase activity in cancer cells by binding to TERT mRNA and regulating TERT translation. In this review, we provide an update on miRNAs that influence telomerase activity by regulation of TERT translation.

Oligonucleotides and microRNAs Targeting Telomerase Subunits in Cancer Therapy

Telomerase provides cancer cells with replicative immortality, and its overexpression serves as a near-universal marker of cancer. Anti-cancer therapeutics targeting telomerase have garnered interest as possible alternatives to chemotherapy and radiotherapy. Oligonucleotide-based therapies that inhibit telomerase through direct or indirect modulation of its subunits, human telomerase reverse transcriptase (hTERT) and human telomerase RNA gene (hTERC), are a unique and diverse subclass of telomerase inhibitors which hold clinical promise. MicroRNAs that play a role in the upregulation or downregulation of hTERT and respective progression or attenuation of cancer development have been effectively targeted to reduce telomerase activity in various cancer types. Tumor suppressor miRNAs, such as miRNA-512-5p, miRNA-138, and miRNA-128, and oncogenic miRNAs, such as miRNA-19b, miRNA-346, and miRNA-21, have displayed preclinical promise as potential hTERT-based therapeutic targets. Antisense oligonucleotides like GRN163L and T-oligos have also been shown to uniquely target the telomerase subunits and have become popular in the design of novel cancer therapies. Finally, studies suggest that G-quadruplex stabilizers, such as Telomestatin, preserve telomeric oligonucleotide architecture, thus inhibiting hTERC binding to the telomere. This review aims to provide an adept understanding of the conceptual foundation and current state of therapeutics utilizing oligonucleotides to target the telomerase subunits, including the advantages and drawbacks of each of these approaches.

Elevation of microRNA-512-5p inhibits MUC1 to reduce radioresistance in cervical cancer

Researches about the role of several microRNAs (miRNAs) in cervical cancer were performed by previous studies, but the function of miR-512-5p in cervical cancer is rare to see. Thus, we aimed to investigate the effect and mechanism of miR-512-5p on radiosensitivity in cervical cancer by regulating MUC1 expression. First, 111 patients with cervical cancer were divided into radiotherapy sensitive group and radiotherapy resistant group. After that, miR-512-5p expression in cancer tissues from two groups was detected. Next, RT-qPCR was used to detect miR-512-5p expression in radiotherapy resistant cervical cancer cells SiHa and radiotherapy sensitive cervical cancer cells Me180. Moreover, SiHa and Me180 cells were treated with miR-512-5p overexpression and MUC1 poor expression plasmids. With 0 Gy, 2 Gy, 4 Gy, 6 Gy and 8 Gy irradiation, proliferation, colony formation ability and apoptosis of cervical cancer cells were determined. Also, cell lines that overexpressed miR-512-5p and overexpressed MUC1 were then constructed to observe the changes in cell radiosensitivity. MiR-512-5p was down-regulated and MUC1 was up-regulated in radiotherapy resistant cervical cancer tissues and cells. Overexpression of miR-512-5p and down-regulation of MUC1 increased the apoptosis and reduced cell survival rate of cervical cancer cells after radiotherapy. Overexpression of miR-512-5p reversed the effect of MUC1 overexpression on decreasing cell apoptosis and elevating cell survival rate of cervical cancer cells. Our study provides evidence that elevation of miR-512-5p contributes to the reduction of radioresistance in cervical cancer cells by inhibiting MUC1 expression.

Elevation of microRNA-512-5p inhibits MUC1 to reduce radioresistance in cervical cancer

Researches about the role of several microRNAs (miRNAs) in cervical cancer were performed by previous studies, but the function of miR-512-5p in cervical cancer is rare to see. Thus, we aimed to investigate the effect and mechanism of miR-512-5p on radiosensitivity in cervical cancer by regulating MUC1 expression. First, 111 patients with cervical cancer were divided into radiotherapy sensitive group and radiotherapy resistant group. After that, miR-512-5p expression in cancer tissues from two groups was detected. Next, RT-qPCR was used to detect miR-512-5p expression in radiotherapy resistant cervical cancer cells SiHa and radiotherapy sensitive cervical cancer cells Me180. Moreover, SiHa and Me180 cells were treated with miR-512-5p overexpression and MUC1 poor expression plasmids. With 0 Gy, 2 Gy, 4 Gy, 6 Gy and 8 Gy irradiation, proliferation, colony formation ability and apoptosis of cervical cancer cells were determined. Also, cell lines that overexpressed miR-512-5p and overexpressed MUC1 were then constructed to observe the changes in cell radiosensitivity. MiR-512-5p was down-regulated and MUC1 was up-regulated in radiotherapy resistant cervical cancer tissues and cells. Overexpression of miR-512-5p and down-regulation of MUC1 increased the apoptosis and reduced cell survival rate of cervical cancer cells after radiotherapy. Overexpression of miR-512-5p reversed the effect of MUC1 overexpression on decreasing cell apoptosis and elevating cell survival rate of cervical cancer cells. Our study provides evidence that elevation of miR-512-5p contributes to the reduction of radioresistance in cervical cancer cells by inhibiting MUC1 expression.

Noncoding RNAs Controlling Telomere Homeostasis in Senescence and Aging

Aging is a universal and time-dependent biological decline associated with progressive deterioration of cells, tissues, and organs. Age-related decay can eventually lead to pathology such as cardiovascular and neurodegenerative diseases, cancer, and diabetes. A prominent molecular process underlying aging is the progressive shortening of telomeres, the structures that protect the ends of chromosomes, eventually triggering cellular senescence. Noncoding (nc)RNAs are emerging as major regulators of telomere length homeostasis. In this review, we describe the impact of ncRNAs on telomere function and discuss their implications in senescence and age-related diseases. We discuss emerging therapeutic strategies targeting telomere-regulatory ncRNAs in aging pathology.

Circular RNA hsa_circ_0004277 contributes to malignant phenotype of colorectal cancer by sponging miR-512-5p to upregulate the expression of PTMA

In recent years, extensive reports have been published concerning the molecular mechanism underlying the occurrence and progression of colorectal cancer. Circular RNAs (circRNAs) have been identified as important modulators in the biological processes of colorectal cancer. Microarray analysis unveiled that differential circ-0004277 expression was identified in tissue samples of colorectal cancer. High circ-0004277 expression was then verified in tissue samples and cell lines of colorectal cancer via qRT-PCR. Kaplan-Meier analysis was used for identifying the association between circ-0004277 expression and the overall survival rate of colorectal cancer patients. A relationship existed between higher circ-0004277 expression and decreased overall survival rate of colorectal cancer patients. From a functional perspective, circ-0004277 knockdown accelerated cell apoptosis and restrained cell proliferation of colorectal cancer. From mechanistic perspective, circ-0004277 upregulated PTMA by sponging miR-512-5p. Rescue assay was used for verifying the roles of the circ-0004277-miR-512-5p-PTMA axis. Both miR-512-5p and PTMA participated in circ-0004277-mediated colorectal cancer cell proliferation based on experiments. In summary, our study showed that circ-0004277 promoted the proliferation of colorectal cancer cells as a miR-512-5p sponge to upregulate the PTMA expression.

miR-512-5p suppresses the progression of non-small cell lung cancer by targeting β-catenin

The oncogenic protein β-catenin is regulated by microRNAs (miRs) in non-small cell lung cancer (NSCLC). miR-512-5p is downregulated in NSCLC compared with healthy tissues and exhibits a tumour-suppressive effect. To study whether miR-512-5p acts on β-catenin to exert its anticancer effect in NSCLC, miR-512-5p mimic and inhibitor were transfected into NSCLC A549 and H1975 cells. miR-512-5p mimic inhibited the invasion of NSCLC cells and increased apoptosis, which suggested an inhibitory effect of miR-512-5p in NSCLC progression in vitro. By contrast, transfection with the miR-512-5p inhibitor resulted in the opposite effects. A dual-luciferase assay demonstrated that miR-512-5p complementarily bound to the 3′-untranslated region of β-catenin. miR-512-5p mimic suppressed the transcription and translation of β-catenin and reduced the expression of the downstream oncogenes cyclin D1 and matrix metalloproteinases, leading to the inhibition of Wnt/β-catenin signalling and subsequent inhibition of NSCLC tumourigenesis in vitro. In conclusion, miR-512-5p may function as a tumour suppressor in NSCLC by inhibiting the Wnt/β-catenin pathway.

Diverse regulatory manners of human telomerase reverse transcriptase

Human telomerase reverse transcriptase (hTERT) is the core subunit of human telomerase and plays important roles in human cancers. Aberrant expression of hTERT is closely associated with tumorigenesis, cancer cell stemness maintaining, cell proliferation, apoptosis inhibition, senescence evasion and metastasis. The molecular basis of hTERT regulation is highly complicated and consists of various layers. A deep and full-scale comprehension of the regulatory mechanisms of hTERT is pivotal in understanding the pathogenesis and searching for therapeutic approaches. In this review, we summarize the recent advances regarding the diverse regulatory mechanisms of hTERT, including the transcriptional (promoter mutation, promoter region methylation and histone acetylation), post-transcriptional (mRNA alternative splicing and non-coding RNAs) and post-translational levels (phosphorylation and ubiquitination), which may provide novel perspectives for further translational diagnosis or therapeutic strategies targeting hTERT.

The Roles of MicroRNA in Lung Cancer

Lung cancer is the most devastating malignancy in the world. Beyond genetic research, epigenomic studies—especially investigations of microRNAs—have grown rapidly in quantity and quality in the past decade. This has enriched our understanding about basic cancer biology and lit up the opportunities for potential therapeutic development. In this review, we summarize the involvement of microRNAs in lung cancer carcinogenesis and behavior, by illustrating the relationship to each cancer hallmark capability, and in addition, we briefly describe the clinical applications of microRNAs in lung cancer diagnosis and prognosis. Finally, we discuss the potential therapeutic use of microRNAs in lung cancer.

miR‑512‑5p suppresses proliferation, migration and invasion, and induces apoptosis in non‑small cell lung cancer cells by targeting ETS1

An increasing number of microRNA (miRNA) have been demonstrated to serve as molecular biomarkers for tumor cell progression. miR-512-5p was revealed as oncogenic regulator in several types of cancer. However, whether and how miR-512-5p regulates non-small cell lung cancer (NSCLC) remains unclear. In the present study, the expression of miR-512-5p was detected in NSCLC tissues and cell lines. Then, the proliferation, migration, invasion and apoptosis in NSCLC A549 and H1299 cell lines were detected when miR-512-5p was overexpressed. Furthermore, the underlying mechanism was identified. The level of miR-512-5p was decreased in NSCLC tissues and in NSCLC cells compared with adjacent normal tissues and normal lung tissue cell lines. miR-512-5p mimics inhibited the cell proliferation, migration, invasion and induced apoptosis in A549 and H1299 cells. In addition, a luciferase reporter assay suggested that overexpression of miR-512-5p may decrease the expression of the E26 transformation specific-1 (ETS1) gene; it was subsequently verified that downregulation of the ETS1 gene inhibited cell proliferation and migration and induced cell apoptosis in A549 and H1299 cells, and ETS1 small interfering RNA in the presence of an miR-512-5p inhibitor reversed the effect. The data described in the present study suggest that miR-512-5p may be a tumor suppressor and a potential treatment target in NSCLC.

MiR-31 is a potential biomarker for diagnosis of head and neck squamous cell carcinoma

MicroRNAs (miRNAs) play important roles in the development of head and neck squamous cell carcinoma (HNSCC). However, their potential clinical value as biomarkers remains poorly known. The aim of this study was to assess the association between tissue/serum miR-31 expression levels and prognosis of HNSCC. In this clinical study, tumor samples were obtained from 118 patients with HNSCC and 48 patients with oral epithelial dysplasia, and blood samples were collected from all the HNSCC cases and 60 normal controls. The expression levels of tissue/serum miR-31 were measured by real-time PCR. Chi-square test was used to evaluate the correlation between tissue/serum miR-31 and clinical parameters of HNSCC. Survival curves were constructed using the Kaplan-Meier method and log-rank test. Multivariate Cox regression analyses were used to estimate independent predictors of survival for HNSCC. Our findings showed that tissue miR-31 levels in HNSCC tumor specimens exhibited higher than that in oral epithelial dysplasia samples and normal tissues. Oral epithelial dysplasia with higher expression of miR-31 was more prone to progress into HNSCC. Likewise, serum miR-31 expression in HNSCC patients was markedly increased in compared to normal controls. Moreover, serum miR-31 performed well to distinguish HNSCC subjects from controls. In addition, increased tissue/serum miR-31 expression was positively correlated with poor clinical variables and dismal prognosis. Finally, tissue miR-31 was confirmed to be an independent prognostic factor for HNSCC. Taken together, miR-31 had strong potential as a promising biomarker in HNSCC detection.

MicroRNA Regulation of Telomerase Reverse Transcriptase (TERT): Micro Machines Pull Strings of Papier-Mâché Puppets

Substantial fraction of high-quality information is continuously being added into the existing pool of knowledge related to the biology of telomeres. Based on the insights gleaned from decades of research, it is clear that chromosomal stability needs a highly controlled and dynamic balance of DNA gain and loss in each terminal tract of telomeric repeats. Telomeres are formed by tandem repeats of TTAGGG sequences, which are gradually lost with each round of division of the cells. Targeted inhibition of telomerase to effectively induce apoptosis in cancer cells has attracted tremendous attention and overwhelmingly increasingly list of telomerase inhibitors truthfully advocates pharmacological significance of telomerase. Telomerase reverse transcriptase (TERT) is a multi-talented and catalytically active component of the telomerase-associated protein machinery. Different proteins of telomerase-associated machinery work in a synchronized and orchestrated manner to ensure proper maintenance of telomeric length of chromosomes. Rapidly emerging scientific findings about regulation of TERT by microRNAs has revolutionized our understanding related to the biology of telomeres and telomerase. In this review, we have comprehensively discussed how different miRNAs regulate TERT in different cancers. Use of miRNA-based therapeutics against TERT in different cancers needs detailed research in preclinical models for effective translation of laboratory findings to clinically effective therapeutics.

Mechanisms of human telomerase reverse transcriptase (hTERT) regulation: clinical impacts in cancer

Background

Limitless self-renewal is one of the hallmarks of cancer and is attained by telomere maintenance, essentially through telomerase (hTERT) activation. Transcriptional regulation of hTERT is believed to play a major role in telomerase activation in human cancers.

Main body

The dominant interest in telomerase results from its role in cancer. The role of telomeres and telomere maintenance mechanisms is well established as a major driving force in generating chromosomal and genomic instability. Cancer cells have acquired the ability to overcome their fate of senescence via telomere length maintenance mechanisms, mainly by telomerase activation.

hTERT expression is up-regulated in tumors via multiple genetic and epigenetic mechanisms including hTERT amplifications, hTERT structural variants, hTERT promoter mutations and epigenetic modifications through hTERT promoter methylation. Genetic (hTERT promoter mutations) and epigenetic (hTERT promoter methylation and miRNAs) events were shown to have clinical implications in cancers that depend on hTERT activation. Knowing that telomeres are crucial for cellular self-renewal, the mechanisms responsible for telomere maintenance have a crucial role in cancer diseases and might be important oncological biomarkers. Thus, rather than quantifying TERT expression and its correlation with telomerase activation, the discovery and the assessment of the mechanisms responsible for TERT upregulation offers important information that may be used for diagnosis, prognosis, and treatment monitoring in oncology. Furthermore, a better understanding of these mechanisms may promote their translation into effective targeted cancer therapies.

Conclusion

Herein, we reviewed the underlying mechanisms of hTERT regulation, their role in oncogenesis, and the potential clinical applications in telomerase-dependent cancers.

Modulation of Telomerase Activity in Cancer Cells by Dietary Compounds: A Review

Telomerase is expressed in ~90% of human cancer cell lines and tumor specimens, whereas its enzymatic activity is not detectable in most human somatic cells, suggesting that telomerase represents a highly attractive target for selective cancer treatment. Accordingly, various classes of telomerase inhibitors have been screened and developed in recent years. We and other researchers have successfully found that some dietary compounds can modulate telomerase activity in cancer cells. Telomerase inhibitors derived from food are subdivided into two groups: one group directly blocks the enzymatic activity of telomerase (e.g., catechin and sulfoquinovosyldiacylglycerol), and the other downregulates the expression of human telomerase reverse transcriptase (hTERT), the catalytic subunit of human telomerase, via signal transduction pathways (e.g., retinoic acid and tocotrienol). In contrast, a few dietary components, including genistein and glycated lipid, induce cellular telomerase activity in several types of cancer cells, suggesting that they may be involved in tumor progression. This review summarizes the current knowledge about the effects of dietary factors on telomerase regulation in cancer cells and discusses their molecular mechanisms of action.

Regulation of Signaling Pathways Involved in the Anti-proliferative and Apoptosis-inducing Effects of M22 against Non-small Cell Lung Adenocarcinoma A549 Cells

The compound 29-(4-methylpiperazine)-luepol (M22), a novel derivative of lupeol has shown anti-proliferative effects against the human non-small cell lung cancer A549 cell line. M22 showed significant anti-proliferative activity at 6.80 μM and increased accumulation of G1 cells and effectively suppressed expression of the G1 arrest-related genes cyclins D1 and E1, CDK2 and CDC25A. This was further confirmed by Western blotting demonstrating decreased cyclin D1 and CDC25A protein levels. Furthermore, M22 caused induction of apoptosis that downregulated the anti-apoptotic BCL-2 gene and increased expression of BAX, CASP3 and CASP9 as well as the APAF1 gene. The effect of caspase-induced apoptosis was confirmed by an increase in reactive oxygen species (ROS), loss of mitochondrial membrane potential (MMP). Taken together, our findings indicated that M22 possessed potent anti-proliferative and apoptotic activities.

miR-138-5p acts as a tumor suppressor by targeting hTERT in human colorectal cancer

Colorectal cancer (CRC) is the second most common cancer in the world. The incidence of this cancer is increasing in the developing countries. Mechanism of CRC tumorigenesis has been widely studied at the molecular levels, and has been recently proposed microRNAs as novel players in CRC. It has been reported that microRNA-138-5p (miR-138-5p) play key roles in different kinds of human cancers. However, the roles and underlying molecular mechanisms of miR-138-5p in CRC have not been adequately elucidated. Thus, the aim of the present study was to investigate the roles and possible regulatory mechanisms of miR-138-5p in CRC. In this study, we demonstrated that miR-138-5p was significantly down-regulated in CRC tissue samples and cell lines. Functional analyses indicated that the overexpression of miR-138-5p significantly delayed cell proliferation, reduced colony formation and increased apoptosis in CRC cell lines. Moreover, human telomerase reverse transcriptase (hTERT), an important oncogene in the management of tumors, was confirmed as a direct target of miR-138-5p in CRC cells. We also found that the hTERT expression was increased in CRC tissues and was inversely correlated with miR-138-5p. Further study showed that the restoration of hTERT expression by an overexpressing plasmid could reverse the effects of miR-138-5p on proliferation and apoptosis of CRC cells. Taken together, these data defines a major suppresses proliferation and promotes apoptosis role for miR-138-5p, a microRNA functions as a tumor suppressor in CRC, by directly targeting hTERT, which would be provide a new strategy for future CRC therapies.

Role of non-coding RNAs in head and neck squamous cell carcinoma: A narrative review

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide with high recurrence, metastasis, and poor treatment outcome. Recent studies have reported that non-coding RNA (ncRNA) might play critical role in regulating different types of cancer. MicroRNAs (miRs) are short ncRNAs (20-25 nucleotides) responsible for post-transcriptional regulation of gene expression and may have a role in oncogenesis by acting as oncomiRs or tumor suppressor miRs. Long non-coding RNAs (lncRNAs) are heterogenous group of ncRNAs more than 200 nucleotides long, can act in cis and/or in trans, and have been also implicated in carcinogenesis. These molecules have been suggested to be promising candidates as diagnostic and prognostic biomarkers and for development of novel therapeutic approaches. In this review, we have summarized recent findings on role of these ncRNAs in HPV-negative (HPV-ve) and HPV-positive (HPV+ve) HNSCC. The available literature supports differential expression of both microRNAs and long non-coding RNAs, which include oncogenic ncRNAs (miR-21, miR-31, miR-155, miR-211, HOTAIR, and MALAT1) and tumor suppressor ncRNAs (let7d, miR-17, miR-375, miR-139, and MEG3) in HPV+ve HNSCC tumors as compared to HPV-ve tumors and they have distinct role in the pathophysiology of these two types of HNSCCs.

Epigenetic silencing of miR-296 and miR-512 ensures hTERT dependent apoptosis protection and telomere maintenance in basal-type breast cancer cells

The catalytic subunit of the telomerase complex, hTERT, ensures unlimited proliferative potential of cancer cells by maintaining telomere function and protecting from apoptosis. Using a miRNA screening approach we identified miR-296-5p and miR-512-5p as miRNAs that target hTERT in breast cancer cells. Ectopic miR-296-5p and miR-512-5p reduce telomerase activity, drive telomere shortening and cause proliferation defects by enhancing senescence and apoptosis in breast cancer cells. In line with the relevance of hTERT expression for human cancer we found that miR-296-5p and miR-512-5p expression is reduced in human breast cancer. Accordingly, high expression of miR-296-5p and miR-512-5p target genes including hTERT is linked with significantly reduced distant metastasis free survival and relapse free survival of basal type breast cancer patients. This suggests relevance of the identified miRNAs in basal type breast cancer. Epigenetic silencing of miR-296 and miR-512 encoding genes is responsible for low levels of miR-296-5p and miR-512-5p expression in basal type breast cancer cells. Disrupting gene silencing results in a dramatic upregulation of miR-296-5p and miR-512-5p levels leading to reduced hTERT expression and increased sensitivity to the induction of apoptosis. Altogether, our data suggest that epigenetic regulatory circuits in basal type breast cancer may contribute to high hTERT levels by silencing miR-296-5p and miR-512-5p expression, thereby contributing to the aggressiveness of basal type breast cancer.

Are microRNAs true sensors of ageing and cellular senescence?

All living beings are programmed to death due to aging and age-related processes. Aging is a normal process of every living species. While all cells are inevitably progressing towards death, many disease processes accelerate the aging process, leading to senescence. Pathologies such as Alzheimer's disease, Parkinson's disease, multiple sclerosis, amyotrophic lateral sclerosis, Huntington's disease, cardiovascular disease, cancer, and skin diseases have been associated with deregulated aging. Healthy aging can delay onset of all age-related diseases. Genetics and epigenetics are reported to play large roles in accelerating and/or delaying the onset of age-related diseases. Cellular mechanisms of aging and age-related diseases are not completely understood. However, recent molecular biology discoveries have revealed that microRNAs (miRNAs) are potential sensors of aging and cellular senescence. Due to miRNAs capability to bind to the 3' untranslated region (UTR) of mRNA of specific genes, miRNAs can prevent the translation of specific genes. The purpose of our article is to highlight recent advancements in miRNAs and their involvement in cellular changes in aging and senescence. Our article discusses the current understanding of cellular senescence, its interplay with miRNAs regulation, and how they both contribute to disease processes.

Functional ectopic neuritogenesis by retinal rod bipolar cells is regulated by miR-125b-5p during retinal remodeling in RCS rats

Following retinal degeneration, retinal remodeling can cause neuronal microcircuits to undergo structural alterations, which particularly affect the dendrites of bipolar cells. However, the mechanisms and functional consequences of such changes remain unclear. Here, we used Royal College of Surgeon (RCS) rats as a model of retinal degeneration, to study structural changes in rod bipolar cells (RBCs) and the underlying mechanisms of these changes. We found that, with retinal degeneration, RBC dendrites extended into the outer nuclear layer (ONL) of the retina, and the ectopic dendrites formed synapses with the remaining photoreceptors. This ectopic neuritogenesis was associated with brain-derived neurotrophic factor (BDNF) - expression of which was negatively regulated by miR-125b-5p. Overexpression of miR-125b-5p in the retinae of RCS rats diminished RBC ectopic dendrites, and compromised the b-wave of the flash electroretinogram (ERG). In contrast, down-regulation of miR-125b-5p (or exogenous BDNF treatment) increased RBC ectopic dendrites, and improved b-wave. Furthermore, we showed that the regulation of ectopic neuritogenesis by BDNF occurred via the downstream modulation of the TrkB-CREB signaling pathway. Based on these findings, we conclude that ectopic dendrites are likely to be providing functional benefits and that, in RCS rats, miR-125b-5p regulates ectopic neuritogenesis by RBCs through modulation of the BDNF-TrkB-CREB pathway. This suggests that therapies that reduce miR-125b-5p expression could be beneficial in human retinal degenerative disease.

Impact of microRNA dynamics on cancer hallmarks: An oral cancer scenario

MicroRNAs are endogenous small noncoding RNAs that negatively regulate gene expression at posttranscriptional level. The discovery of microRNAs has identified a new layer of gene regulation mechanisms, which play a pivotal role in development as well as in various cellular processes, such as proliferation, differentiation, cell growth, and cell death. Deregulated microRNA expression favors acquisition of cancer hallmark traits as well as transforms the tumor microenvironment, leading to tumor development and progression. Many recent studies have revealed altered expression of microRNAs in oral carcinoma with several microRNAs shown to have key biological role in tumorigenesis functioning either as tumor suppressors or as tumor promoters. MicroRNA expression levels correlate with clinicopathological variables and have a diagnostic and prognostic value in oral carcinoma. For these reasons, microRNA has been a hot topic in oral cancer research for the last few years. In this review, we attempt to summarize the present understanding of microRNA deregulation in oral carcinoma, their role in acquiring cancer hallmarks, and their potential diagnostic and prognostic value for oral cancer management.

Epigenetic perturbation driving asleep telomerase reverse transcriptase: Possible therapeutic avenues in carcinoma

In the last decade, implications of human telomerase reverse transcriptase (hTERT), a component of ribonucleoprotein telomerase in aging, senescence, and stem cell are highly evident. Besides, the activation of hTERT is also being documented several cancer types including carcinoma. The awakening of telomerase during carcinoma initiation and development is being seen with different perspectives including genetic and epigenetic tools and events. In view of several tumor progenitors genes (also referred as epigenetic mediators), telomerase is placed as key enzyme to achieve the carcinoma phenotype and sustain during the progression. It is true that swaying of telomerase in carcinoma could be facilitated with dedicated set of epigenetic modulators and modifiers players. These epigenetic alterations are heritable, potentially reversible, and seen as the epigenetic signature of carcinoma. Several papers converge to suggest that DNA methylation, histone modification, and small non-coding RNAs are the widely appreciated epigenetic changes towards hTERT modulation. In this review, we summarize the contribution of epigenetic factors in the telomerase activation and discuss potential avenues to achieve therapeutic intervention in carcinoma.

MicroRNA-532 and microRNA-3064 inhibit cell proliferation and invasion by acting as direct regulators of human telomerase reverse transcriptase in ovarian cancer

Human telomerase reverse transcriptase (hTERT) plays a crucial role in ovarian cancer (OC) progression. However, the mechanisms underlying hTERT upregulation in OC, and the specific microRNAs (miRNAs) involved in the regulation of hTERT in OC cells, remains unclear. We performed a bioinformatics search to identify potential miRNAs that bind to the 3'-untranslated region (3'-UTR) region of the hTERT mRNA. We examined the expression levels of miR-532/miR-3064 in OC tissues and normal ovarian tissues, and analyzed the correlation between miRNA expression and OC patient outcomes. The impacts of miR-532/miR-3064 on hTERT expression were evaluated by western blot analysis and hTERT 3'-UTR reporter assays. We investigated the effects of miR-532/miR-3064 on proliferation and invasion in OC cells. We found that miR-532 and miR-3064 are down-regulated in OC specimens. We observed a significant association between reduced miR-532/miR-3064 expression and poorer survival of patients with OC. We confirmed that in OC cells, these two miRNAs downregulate hTERT levels by directly targeting its 3'-UTR region, and inhibited proliferation, EMT and invasion of OC cells. In addition, the overexpression of the hTERT cDNA lacking the 3'-UTR partially restored miR-532/miR-3064-inhibited OC cell proliferation and invasion. The silencing of hTERT by siRNA oligonucleotides abolished these malignant features, and phenocopied the effects of miR-532/miR-3064 overexpression. Furthermore, overexpression of miR-532/miR-3064 inhibits the growth of OC cells in vivo. Our findings demonstrate a miR-532/miR-3064-mediated mechanism responsible for hTERT upregulation in OC cells, and reveal a possibility of targeting miR-532/miR-3064 for future treatment of OC.

Gene expression of miRNA-138 and cyclin D1 in oral lichen planus

OBJECTIVES

This study aimed to evaluate microRNA-138 (miR-138) gene expression and its target cyclin D1 (CCND1) gene and protein expression in oral lichen planus (OLP) mucosa in an attempt to investigate their possible roles in OLP immunopathogenesis.

METHODS

Sixty oral biopsy specimens were harvested from 30 healthy subjects and 30 OLP patients, subdivided into reticular, atrophic, and erosive groups (n = 10 each). Samples were subjected to quantitative real-time polymerase chain reaction analysis for quantification of miR-138 and CCND1 relative gene expression and immunohistochemical analysis to determine CCND1 protein expression.

RESULTS

Samples from OLP patients had a significant underexpression of miR-138 gene and overexpression of CCND1 at both gene and protein levels compared to normal mucosa samples. The lowest levels of miR-138 expression were observed in atrophic and erosive OLP compared to reticular OLP, and the highest levels of CCND1 gene and protein expression were in atrophic OLP. An inverse correlation was demonstrated between the miR-138 expression and both CCND1 gene and protein expression in OLP patients. A significant positive correlation between CCND1 gene and protein expression was also observed.

CONCLUSION

Downregulation of miR-138 increases the gene and protein expression of its potential target CCND1 in OLP mucosa which might have a pivotal role in the disease pathogenesis.

CLINICAL RELEVANCE

This research implied that miR-138 may have a role in identification of symptomatic OLP lesions. MiR-138 might be considered as a potential tool in future OLP molecular therapy.