MiR-766 induces p53 accumulation and G2/M arrest by directly targeting MDM4

The crosstalk between non-coding RNAs and cell-cycle events: A new frontier in cancer therapy

The cell cycle comprises sequential events during which a cell duplicates its genome and divides it into two daughter cells. This process is tightly regulated to ensure that the daughter cell receives identical copied chromosomal DNA and that any errors in the DNA during replication are correctly repaired. Cyclins and their enzyme partners, cyclin-dependent kinases (CDKs), are critical regulators of G- to M-phase transitions during the cell cycle. Mitogenic signals induce the formation of the cyclin/CDK complexes, resulting in phosphorylation and activation of the CDKs. Once activated, cyclin/CDK complexes phosphorylate specific substrates that drive the cell cycle forward. The sequential activation and inactivation of cyclin-CDK complexes are tightly controlled by activating and inactivating phosphorylation events induced by cell-cycle proteins. The non-coding RNAs (ncRNAs), which do not code for proteins, regulate cell-cycle proteins at the transcriptional and translational levels, thereby controlling their expression at different cell-cycle phases. Deregulation of ncRNAs can cause abnormal expression patterns of cell-cycle-regulating proteins, resulting in abnormalities in cell-cycle regulation and cancer development. This review explores how ncRNA dysregulation can disrupt cell division balance and discusses potential therapeutic approaches targeting these ncRNAs to control cell-cycle events in cancer treatment.

Actoeside mitigated the renal proximal tubule cells damage triggered by high glucose through miR-766/VCAM1/NF-κB signalling pathway

CONTEXT

Diabetic nephropathy (DN) triggered by diabetes mellitus is one of the primary causes of end-stage renal failure worldwide.

OBJECTIVE

This study intends to explore the function and potential mechanism of actoeside on renal proximal tubule (HK-2) cells damage induced by high-glucose (HG).

METHODS

The DN model was established in HK-2 cells with 30 mM HG treatment. The viability, apoptosis and inflammation of HK-2 cells were analysed severally via CCK-8, flow cytomery and ELISA. The key factors related to NF-κB were detected by western blotting.

RESULTS

Actoeside attenuated the HG-induced HK-2 cells damage. The differentially expression of miR-766 and VCAM1 in DN patients was reversed by actoeside. Moreover, the increased phosphorylation levels of p65 NF-κB/IκBα induced by HG were attenuated by actoeside.

CONCLUSIONS

Actoeside promoted the growth and repressed the apoptosis and inflammation of HK-2 cells via miR-766/VCAM1/NF-κB signalling pathway, affording a promising idea for the treatment of DN.

Melatonin enhances cell death and suppresses the metastatic capacity of ovarian cancer cells by attenuating the signaling of multiple kinases

BACKGROUND

Ovarian cancer is a highly aggressive disease that is frequently diagnosed in advanced stages. Melatonin, with its numerous antitumor properties, holds great promise in cancer treatment. Herein, we investigated the effects of melatonin on apoptosis, cell migration, and kinase levels in human ovarian carcinoma SKOV-3 cells and determined whether these effects are mediated by the activation of the MT1 receptor.

METHODS

SKOV-3 cells were exposed to different concentrations of melatonin based on the presence of MT1 receptor, and we also performed specific silencing of the melatonin receptor gene MTNR1A.

RESULTS

Our findings revealed that melatonin reduced cell viability as shown by the MTT assay, and flow cytometry analysis showed increased rates of apoptosis and necrosis in all melatonin-treated cells. Melatonin significantly decreased the migratory and invasive capacities of the cells. Propidium iodide labeling indicated that melatonin induced cell cycle arrest by reducing DNA content in the S and G2/M phases in SKOV-3 cells. Additionally, the levels of AKT, ERK1/2, JNK, CREB, p70S6K, STAT3/5, and p38 MAP kinase involved in cell survival, proliferation, motility, and stress responses were depressed by melatonin and further reduced after MT1 knockdown. These molecules were found to be associated with lower overall survival in ovarian cancer patients.

CONCLUSIONS

Melatonin had obvious oncostatic actions on ovarian cancer cells, and MT1 receptor knockdown intensified its antitumor effect. The inhibition of the MT1 receptor resulted in a substantial reduction in the migratory and invasive capacities of the cells, suggesting its potential as a therapeutic target for the treatment of ovarian cancer.

MiR-766-3p and miR-671-5p attenuate aristolochic acid-induced hepatotoxicity by directly targeting the key bioactivating enzyme NQO1

Aristolochic acid (AA) as an emerging contaminant in herbal medicines or crops has been well-recognized for causing nephropathy since 1990s. Over the last decade, mounting evidence has linked AA to liver injury; however, the underlying mechanism is poorly elucidated. MicroRNAs respond to environmental stress and mediate multiple biological processes, thus showing biomarker potentials prognostically or diagnostically. In the present study, we investigated the role of miRNAs in AA-induced hepatotoxicity, specifically in regulating NQO1, the key enzyme responsible for AA bioactivation. In silico analysis showed that hsa-miR-766-3p and hsa-miR-671-5p were significantly associated with AAI exposure as well as NQO1 induction. A 28-day rat experiment of 20 mg/kg AA exposure demonstrated a 3-fold increase of NQO1 and an almost 50 % decrease of the homologous miR-671 that were accompanied with liver injury, which was consistent with in silico prediction. Further mechanistic investigation using Huh7 cells with IC50 of AAI at 146.5 µM showed both hsa-miR-766-3p and hsa-miR-671-5p were able to directly bind to and down-regulate NQO1 basal expression. In addition, both miRNAs were shown to suppress AAI-induced NQO1 upregulation in Huh7 cells at a cytotoxic concentration of 70 μM, and consequently alleviate AAI-induced cellular effects, including cytotoxicity and oxidative stress. Together, these data illustrate that miR-766-3p and miR-671-5p attenuate AAI-induced hepatotoxicity, and thus have monitoring and diagnostic potentials.

The key role of microRNA-766 in the cancer development

Cancer is caused by defects in coding and non-coding RNAs. In addition, duplicated biological pathways diminish the efficacy of mono target cancer drugs. MicroRNAs (miRNAs) are short, endogenous, non-coding RNAs that regulate many target genes and play a crucial role in physiological processes such as cell division, differentiation, cell cycle, proliferation, and apoptosis, which are frequently disrupted in diseases such as cancer. MiR-766, one of the most adaptable and highly conserved microRNAs, is notably overexpressed in several diseases, including malignant tumors. Variations in miR-766 expression are linked to various pathological and physiological processes. Additionally, miR-766 promotes therapeutic resistance pathways in various types of tumors. Here, we present and discuss evidence implicating miR-766 in the development of cancer and treatment resistance. In addition, we discuss the potential applications of miR-766 as a therapeutic cancer target, diagnostic biomarker, and prognostic indicator. This may shed light on the development of novel therapeutic strategies for cancer therapy.

Plasma miR-151-3p as a Candidate Diagnostic Biomarker for Head and Neck Cancer: A Cross-sectional Study within the INHANCE Consortium

BACKGROUND

Identification of screening tests for the detection of head and neck cancer (HNC) at an early stage is an important strategy to improving prognosis. Our objective was to identify plasma circulating miRNAs for the diagnosis of HNC (oral and laryngeal subsites), within a multicenter International Head and Neck Cancer Epidemiology consortium.

METHODS

A high-throughput screening phase with 754 miRNAs was performed in plasma samples of 88 cases and 88 controls, followed by a validation phase of the differentially expressed miRNAs, identified in the screening, in samples of 396 cases and 396 controls. Comparison of the fold changes (FC) was carried out using the Wilcoxon rank-sum test and the Dunn multiple comparison test.

RESULTS

We identified miR-151-3p (FC = 1.73, P = 0.007) as differentially expressed miRNAs in the screening and validation phase. The miR-151-3p was the only overexpressed miRNA in validation sample of patients with HNC with early stage at diagnosis (FC = 1.81, P = 0.008) and it was confirmed upregulated both in smoker early-stage cases (FC = 3.52, P = 0.024) and in nonsmoker early-stage cases (FC = 1.60, P = 0.025) compared with controls.

CONCLUSIONS

We identified miR-151-3p as an early marker of HNC. This miRNA was the only upregulated in patients at early stages of the disease, independently of the smoking status.

IMPACT

The prognosis for HNC is still poor. The discovery of a new diagnostic biomarker could lead to an earlier tumor discovery and therefore to an improvement in patient prognosis.

From inflammatory bowel disease to colorectal cancer: what's the role of miRNAs?

Inflammatory Bowel Disease (IBD) is a chronic inflammatory disease with relapse and remission periods. Ulcerative colitis and Crohn's disease are two major forms of the disease. IBD imposes a lot of sufferings on the patient and has many consequences; however, the most important is the increased risk of colorectal cancer, especially in patients with Ulcerative colitis. This risk is increased with increasing the duration of disease, thus preventing the progression of IBD to cancer is very important. Therefore, it is necessary to know the details of events contributed to the progression of IBD to cancer. In recent years, the importance of miRNAs as small molecules with 20-22 nucleotides has been recognized in pathophysiology of many diseases, in which IBD and colorectal cancer have not been excluded. As a result, the effectiveness of these small molecules as therapeutic target is hopefully confirmed. This paper has reviewed the related studies and findings about the role of miRNAs in the course of events that promote the progression of IBD to colorectal carcinoma, as well as a review about the effectiveness of some of these miRNAs as therapeutic targets.

MDM4 alternative splicing and implication in MDM4 targeted cancer therapies

The oncogenic MDM4, initially named MDMX, has been identified as a p53-interacting protein and a key upstream negative regulator of the tumor suppressor p53. Accumulating evidence indicates that MDM4 plays critical roles in the initiation and progression of multiple human cancers. MDM4 is frequently amplified and upregulated in human cancers, contributing to overgrowth and apoptosis inhibition by blocking the expression of downstream target genes of p53 pathway. Disruptors for MDM4-p53 interaction have been shown to restore the anti-tumor activity of p53 in cancer cells. MDM4 possesses multiple splicing isoforms whose expressions are driven by the presence of oncogenes in cancer cells. Some of the MDM4 splicing isoforms lack p53 binding domain and may exhibit p53-independent oncogenic functions. These features render MDM4 to be an attractive therapeutic target for cancer therapy. In the present review, we primarily focus on the detailed molecular structure of MDM4 splicing isoforms, candidate regulators for initiating MDM4 splicing, deregulation of MDM4 isoforms in cancer and potential therapy strategies by targeting splicing isoforms of MDM4.

CEACAM Gene Family Mutations Associated With Inherited Breast Cancer Risk - A Comparative Oncology Approach to Discovery

Introduction

Recent studies comparing canine mammary tumors (CMTs) and human breast cancers have revealed remarkable tumor similarities, identifying shared expression profiles and acquired mutations. CMTs can also provide a model of inherited breast cancer susceptibility in humans; thus, we investigated breed-specific whole genome sequencing (WGS) data in search for novel CMT risk factors that could subsequently explain inherited breast cancer risk in humans.

Methods

WGS was carried out on five CMT-affected Gold Retrievers from a large pedigree of 18 CMT-affected dogs. Protein truncating variants (PTVs) detected in all five samples (within human orthlogs) were validated and then genotyped in the 13 remaining CMT-affected Golden Retrievers. Allele frequencies were compared to canine controls. Subsequently, human blood-derived exomes from The Cancer Genome Atlas breast cancer cases were analyzed and allele frequencies were compared to Exome Variant Server ethnic-matched controls.

Results

Carcinoembryonic Antigen-related Cell Adhesion Molecule 24 (CEACAM24) c.247dupG;p.(Val83Glyfs^∗48) was the only validated variant and had a frequency of 66.7% amongst the 18 Golden Retrievers with CMT. This was significant compared to the European Variation Archive (p-value 1.52 × 10^–8) and non-Golden Retriever American Kennel Club breeds (p-value 2.48 × 10^–5). With no direct ortholog of CEACAM24 in humans but high homology to all CEACAM gene family proteins, all human CEACAM genes were investigated for PTVs. A total of six and sixteen rare PTVs were identified in African and European American breast cancer cases, respectively. Single variant assessment revealed five PTVs associated with breast cancer risk. Gene-based aggregation analyses revealed that rare PTVs in CEACAM6, CEACAM7, and CEACAM8 are associated with European American breast cancer risk, and rare PTVs in CEACAM7 are associated with breast cancer risk in African Americans. Ultimately, rare PTVs in the entire CEACAM gene family are associated with breast cancer risk in both European and African Americans with respective p-values of 1.75 × 10^–13 and 1.87 × 10^–04.

Conclusion

This study reports the first association of inherited CEACAM mutations and breast cancer risk, and potentially implicates the whole gene family in genetic risk. Precisely how these mutations contribute to breast cancer needs to be determined; especially considering our current knowledge on the role that the CEACAM gene family plays in tumor development, progression, and metastasis.

The role of miRNAs in MDMX-p53 interplay

MicroRNAs (miRNAs) are endogenous noncoding RNAs of 19-24 nucleotides in length and are tightly related to tumorigenesis and progression. Recent studies have demonstrated that the tumor suppressor p53 and its negative controller MDMX are regulated by miRNAs in different ways. Some miRNAs directly target p53 and regulate its expression and function, whereas some miRNAs target MDMX and regulate p53's activity indirectly. The overexpression of several miRNAs can restore the activity of p53 by negatively regulating MDMX in cancer cells. Therefore, a better understanding of the miRNAs-MDMX-p53 network will put forward potential research directions for developing anticancer therapeutics. In the present review, we mainly focus on the regulatory effects of miRNAs on the MDMX-p53 interplay as well as the role of the miRNAs-MDMX-p53 network in human cancer.

The roles and regulation of MDM2 and MDMX: it is not just about p53

In this review, Klein et al. discuss the p53-independent roles of MDM2 and MDMX. First, they review the structural and functional features of MDM2 and MDMX proteins separately and together that could be relevant to their p53-independent activities. Following this, they summarize how these two proteins are regulated and how they can function in cells that lack p53.

Most well studied as proteins that restrain the p53 tumor suppressor protein, MDM2 and MDMX have rich lives outside of their relationship to p53. There is much to learn about how these two proteins are regulated and how they can function in cells that lack p53. Regulation of MDM2 and MDMX, which takes place at the level of transcription, post-transcription, and protein modification, can be very intricate and is context-dependent. Equally complex are the myriad roles that these two proteins play in cells that lack wild-type p53; while many of these independent outcomes are consistent with oncogenic transformation, in some settings their functions could also be tumor suppressive. Since numerous small molecules that affect MDM2 and MDMX have been developed for therapeutic outcomes, most if not all designed to prevent their restraint of p53, it will be essential to understand how these diverse molecules might affect the p53-independent activities of MDM2 and MDMX.

Non-coding RNA in cancer

Majority of the human genome is transcribed to RNAs that do not encode proteins. These non-coding RNAs (ncRNAs) play crucial roles in regulating the initiation and progression of various cancers. Given the importance of the ncRNAs, the roles of ncRNAs in cancers have been reviewed elsewhere. Thus, in this review, we mainly focus on the recent studies of the function, regulatory mechanism and therapeutic potential of the ncRNAs including microRNA (miRNA), long ncRNA (lncRNA), circular RNA (circRNA) and PIWI interacting RNA (piRNA), in different type of cancers.

Effect of MicroRNA-766 Promotes Proliferation, Chemoresistance, Migration, and Invasion of Breast Cancer Cells

INTRODUCTION

Breast cancer (BCa) remains the most common cancer in women worldwide. It has been shown that microRNAs (miRs) play essential roles in tumorigenesis and progression in many types of cancers, including BCa. We assessed the role of miR-766 on the proliferation, chemosensitivity, migration, and invasion of BCa cells.

MATERIALS AND METHODS

The effect of miR-766 on the proliferation of MCF-7 and T47D BCa cells was evaluated using the MTT assay. The function of miR-766 on the migration and invasion of MCF-7 and T47D cells was examined using Transwell migration and Matrigel invasion assays. Protein expression was evaluated by Western blot. The role of miR-766 on 5-fluorouracil-induced apoptosis in MCF-7 and T47D cells was determined using the Caspase-Glo3/7 assay. A subcutaneous tumor xenograft was performed to examine the effect of miR-766 on tumor growth in vivo.

RESULTS

Upregulation of miR-766 improved the proliferation, invasion, and migration of BCa cells. Furthermore, miR-766 reduced the sensitivity of MCF-7 and T47D cells to 5-fluorouracil treatment. The tumor xenograft experiment showed that miR-766 promoted BCa growth in vivo. miR-766 decreased 5-flurouracil-induced apoptosis by regulation of BAX and Bcl-2 expression. miR-766 also affected the epithelial-mesenchymal transition by altering E-cadherin, N-cadherin, SNAIL, and vimentin expression in MCF-7 and T47D cells. Further study showed that the expression of phosphatase and tensin homolog and phosphorylated AKT in MCF-7 and T47D cells had changed after aberrant expression of miR-766.

CONCLUSION

miR-766 displayed important roles in tumorigenesis and progression in BCa cells and might act as a potential biomarker to predict the chemotherapy response and progression in BCa.

MicroRNA-766 Promotes The Proliferation, Migration And Invasion, And Inhibits The Apoptosis Of Cutaneous Squamous Cell Carcinoma Cells By Targeting PDCD5

Purpose

This study aimed to investigate the regulatory role and mechanism of microRNA-766 (miR-766) on cutaneous squamous cell carcinoma (CSCC) cells.

Methods

The expression of miR-766 and programmed cell death 5 (PDCD5) was detected in CSCC tissues and CSCC cell lines (A431, SCL-1 and DJM-1 cells) by qRT-RCR. The proliferation, colony-forming ability, apoptosis, migration and invasion of A431 and SCL-1 cells was measured by MTT, colony formation, flow cytometry, wound healing and transwell assay, respectively. The interaction between miR-766 and PDCD5 was detected by dual-luciferase reporter gene assay. The expression of matrix metalloproteinase 2 (MMP-2), MMP-9 and PDCD5 was measured by Western blot. In addition, A431 cells were subcutaneously injected into mice, and the tumor volume and weight were measured.

Results

MiR-766 was upregulated, and PDCD5 was downregulated in CSCC tissues and cells. MiR-766 significantly promoted the proliferation, migration and invasion, and inhibited the apoptosis of A431 and SCL-1 cells. MiR-766 also significantly increased the expression of MMP-2 and MMP-9 in A431 and SCL-1 cells. PDCD5 was a target gene of miR-766. PDCD5 significantly reversed the tumor-promoting effect of miR-766 on A431 and SCL-1 cells. In addition, miR-766 inhibitor inhibited the tumor growth in mice.

Conclusion

MiR-766 inhibitor inhibited the proliferation, migration and invasion, and promoted the apoptosis of CSCC cells via downregulating PDCD5.

CASC15 contributes to proliferation and invasion through regulating miR-766-5p/ KLK12 axis in lung cancer

Long non-coding RNAs (lncRNAs) are key mediators of cancer. The dysregulation of a lncRNA, CASC15, has been linked to several cancers, except lung cancer. Here, the aim of the study was to explore the role and mechanism of CASC15 in lung cancer regulation, with the focus on its interaction with a potential target, microRNA-766-5p (miR-766-5p) and an oncogene, kallikrein-related peptidase 12 (KLK12). Quantitative real-time PCR (qRT-PCR) was used to assess levels of CASC15, miR-766-5p and KLK12 in lung cancer tissues or cells. Western blot analysis was used to detect KLK12 protein expression. Ectopic expression of CASC15 was induced by a lentiviral system. CCK-8 and transwell assays were used to evaluate lung cancer cell proliferation and invasion, respectively. The interaction among CASC15, miR-766-5p and KLK12 was investigated by bioinformatical analysis and luciferase assay. In lung cancer tissue and cells, CASC15 was upregulated, while miR-766-5p was downregulated. Overexpression of CASC15 promoted lung cancer cell proliferation and invasion. A negative correlation was found between CASC15 and miR-766-5p levels. Overexpression of miR-766-6p reversed the cancer-promoting role of CASC15 in lung cancer cells, which was mediated by KLK12. The tumor-promoting role of CASC15 and tumor-suppressing role of miR-766-5p were also validated in vivo in tumor bearing mice, and KLK12 was also shown as an important mediator. CASC15 promotes lung cancer through the miR-766-5p/KLK12 axis, indicating that CASC15 is a potential therapeutic in lung cancer.

miRNA-766 induces apoptosis of human colon cancer cells through the p53/Bax signaling pathway by MDM4

miRNAs are closely associated with tumor genesis and development. The present study investigated the role of the expression of miRNA-766 in the survival of patients with colon cancer and the underlying molecular mechanisms. Reverse transcription-quantitative polymerase chain reaction analysis and microarray analysis were used to analyze the expression of miRNA-766. The results revealed that the expression of miRNA-766 was decreased in patients with colon cancer. The overall survival and disease-free survival rates of patients with colon cancer with a high expression of miRNA-766 were prolonged, compared with those with a low expression of miRNA-766. The overexpression of miRNA-766 reduced cell growth and induced apoptosis in colon cancer cells through suppression of the MDM4/p53 pathway. By contrast, the downregulation of miRNA-766 promoted cell growth and reduced apoptosis in colon cancer cells through activation of the MDM4/p53 pathway. The promotion of MDM4 attenuated the anticancer effect of miRNA-766 in colon cancer cells. These results demonstrated that miRNA-766 induced cell apoptosis in human colon cancer through MDM4/p53.

Melatonin is a potential inhibitor of ovarian cancer: molecular aspects

Ovarian cancer is one of the most common causes of morbidity related to gynecologic malignancies. Possible risk factors are including hereditary ovarian cancer, obesity, diabetes mellitus, alcohol consumption, aging, and smoking. Various molecular signaling pathways including inflammation, oxidative stress, apoptosis and angiogenesis are involved in this progression of ovarian cancer. Standard treatments for recently diagnosed patients are Surgery and chemotherapy such as co-treatment with other drugs such that the exploitation of neoadjuvant chemotherapy is expanding. Melatonin (N-acetyl-5-methoxy-tryptamine), an endogenous agent secreted from the pineal gland, has anti-carcinogenic features, such as regulation of estradiol production, cell cycle modulation, stimulation of apoptosis as well as anti-angiogenetic properties, anti-inflammatory activities, significant antioxidant effects and modulation of various immune system cells and cytokines. Multiple studies have shown the significant beneficial roles of melatonin in various types of cancers including ovarian cancer. This paper aims to shed light on the roles of melatonin in ovarian cancer treatment from the standpoint of the molecular aspects.

The long and the short of it: the MDM4 tail so far

The mouse double minute 4 (MDM4) is emerging from the shadow of its more famous relative MDM2 and is starting to steal the limelight, largely due to its therapeutic possibilities. MDM4 is a vital regulator of the tumor suppressor p53. It restricts p53 transcriptional activity and also, at least in development, facilitates MDM2's E3 ligase activity toward p53. These functions of MDM4 are critical for normal cell function and a proper response to stress. Their importance for proper cell maintenance and proliferation identifies them as a risk for deregulation associated with the uncontrolled growth of cancer. MDM4 tails are vital for its function, where its N-terminus transactivation domain engages p53 and its C-terminus RING domain binds to MDM2. In this review, we highlight recently identified cellular functions of MDM4 and survey emerging therapies directed to correcting its dysregulation in disease.

Oncogenic and Tumor-Suppressive Roles of MicroRNAs with Special Reference to Apoptosis: Molecular Mechanisms and Therapeutic Potential

MicroRNAs (miRNAs) are the non-coding class of minute RNA molecules that negatively control post-transcriptional regulation of various functional genes. These miRNAs are transcribed from the loci present in the introns of functional or protein-coding genes, exons of non-coding genes, or even in the 3'-untranslated region (3'-UTR). They have potential to modulate the stability or translational efficiency of a variety of target RNA [messenger RNA (mRNA)]. The regulatory function of miRNAs has been elucidated in several pathological conditions, including neurological (Alzheimer's disease and Parkinson's disease) and cardiovascular conditions, along with cancer. Importantly, miRNA identification in cancer progression and invasion has evolved as an incipient era in cancer treatment. Several studies have shown the influence of miRNAs on various cancer processes, including apoptosis, invasion, metastasis and angiogenesis. In particular, apoptosis induction in tumor cells through miRNA has been extensively studied. The biphasic mode (up- and down-regulation) of miRNA expression in apoptosis and other cancer processes has already been determined. The findings of these studies could be utilized to develop potential therapeutic strategies for the management of various cancers. The present review critically describes the oncogenic and tumor suppressor role of miRNAs in apoptosis and other cancer processes, therapy resistance, and use of their presence in the body fluids as biomarkers.

MicroRNA-766-3p Inhibits Tumour Progression by Targeting Wnt3a in Hepatocellular Carcinoma

Recent studies have indicated that microRNAs (miRNAs) play an important role in hepatocellular carcinoma (HCC) progression. In this study, we showed that miR-766-3p was decreased in approximately 72% of HCC tissues and cell lines, and its low expression level was significantly correlated with tumour size, TNM stage, metastasis, and poor prognosis in HCC. Ectopic miR-766-3p expression inhibited HCC cell proliferation, colony formation, migration and invasion. In addition, we showed that miR-766-3p repressed Wnt3a expression. A luciferase reporter assay revealed that Wnt3a was a direct target of miR-766-3p, and an inverse correlation between miR-766-3p and Wnt3a expression was observed. Moreover, Wnt3a up-regulation reversed the effects of miR-766-3p on HCC progression. In addition, our study showed that miR-766-3p up-regulation decreased the nuclear β-catenin level and expression of Wnt targets (TCF1 and Survivin) and reduced the level of MAP protein regulator of cytokinesis 1 (PRC1). However, these effects of miR-766-3p were reversed by Wnt3a up-regulation. In addition, PRC1 up-regulation increased the nuclear β-catenin level and protein expression of TCF1 and Survivin. iCRT3, which disrupts the β-catenin-TCF4 interaction, repressed the TCF1, Survivin and PRC1 protein levels. Taken together, our results suggest that miR-766-3p down-regulation promotes HCC cell progression, probably by targeting the Wnt3a/PRC1 pathway, and miR-766-3p may serve as a potential therapeutic target in HCC.

miR-503-3p induces apoptosis of lung cancer cells by regulating p21 and CDK4 expression

Studies have shown that microRNAs (miRNAs) can promote or suppress tumor growth and therefore act as targets for cancer therapy. Hsa-miR-503-5p, a mature miRNA derived from 5' ends of pre-miR-503, has been proved to regulate cell proliferation, transformation, migration and invasion. However, the biological function of miR-503-3p derived from 3' ends of pre-miR-503 has never been reported. In current study, we found that miR-503-3p inhibits lung cancer cell viability and induces cell apoptosis. To better understand the molecular mechanism underlying the miR-503-3p participating in this process, PCR array and RNA-sequencing (RNA-seq) were performed and some differential expression genes were discovered between NC and miR-503-3p treated groups. Biological interaction network showed that p21 and CDK4 are the most important proteins involving miR-503-3p signal pathway. Dual-luciferase assay results shown miR-503-3p directly regulates the expression of p21 by targeting 3'-UTR of its mRNA. These results shed light on the potential roles of miR-503-3p, indicating that it may act as an anti-oncogene factor to inhibit lung cancer cell viability.

Friend or Foe: MicroRNAs in the p53 network

The critical tumor suppressor gene TP53 is either lost or mutated in more than half of human cancers. As an important transcriptional regulator, p53 modulates the expression of many microRNAs. While wild-type p53 uses microRNAs to suppress cancer development, microRNAs that are activated by gain-of-function mutant p53 confer oncogenic properties. On the other hand, the expression of p53 is tightly controlled by a fine-tune machinery including microRNAs. MicroRNAs can target the TP53 gene directly or other factors in the p53 network so that expression and function of either the wild-type or the mutant forms of p53 is downregulated. Therefore, depending on the wild-type or mutant p53 context, microRNAs contribute substantially to suppress or exacerbate tumor development.