MicroRNA-200a promotes proliferation and invasion of ovarian cancer cells by targeting PTEN

MicroRNA 142-5p promotes tumor growth in oral squamous cell carcinoma via the PI3K/AKT pathway by regulating PTEN

MicroRNAs (miRNAs) play an important role in carcinogenesis and cancer progression. The purpose of this study was to identify miRNAs associated with carcinoma function in OSCC and to investigate the potential role of the specific miRNAs. First, a comprehensive microarray analysis was performed, and miR-142-5p was identified as a candidate miRNA involved in OSCC. miR-142-5p has been reported to show high expression levels in cancer patients and to be involved in tumor growth and metastasis. However, the expression and function of miR-142-5p in oral squamous cell carcinoma (OSCC) are not fully characterized. We evaluated miR-142-5p expression in both OSCC-derived cell lines and primary OSCC tissues and performed functional analysis of miR-142-5p in OSCC-derived cell lines using mimics and inhibitors. miR-142-5p expression was up-regulated in OSCC tissues and OSCC cell lines. Overexpression of miR-142-5p significantly promoted the proliferation and invasion of OSCC cells. Bioinformatics analysis was performed using TargetScan to predict potential target sites that match the seed region of miR-142-5p. Phosphatase and tensin homolog deleted on chromo-some 10 (PTEN) was identified as a potential target and selected for further analysis. PTEN expression levels were down-regulated and AKT expression levels were up-regulated in miR-142-5p-overexpressing cells. We have shown that miR-142-5p targets the PTEN gene and is involved in cancer progression. Our results suggest that miR-142-5p is involved in the progression of OSCC by controlling the phosphatidylinositol 3-kinase (PI3K)/AKT pathway by targeting the PTEN gene. Our findings suggest that miR-142-5p may be a new target for the treatment of OSCC.

MicroRNA-103a-3p Promotes Cell Proliferation and Invasion in Non-Small-Cell Lung Cancer Cells through Akt Pathway by Targeting PTEN

Background

Increasing evidence has suggested that microRNA- (miR-) 103a-3p is crucial for cancer progression. However, the specific mechanism of miR-103a-3p in non-small-cell lung cancer (NSCLC) remains unclear until now. So, it is particularly urgent to clarify the mechanism between them.

Methods

qRT-PCR and western blot were used to measure the expression of miR-103a-3p, PTEN, Akt, and p-Akt. Cell biology experiment was applied to detect the biological function of miR-103a-3p in NSCLC cell lines. Moreover, bioinformatics analysis, luciferase reporter assay, and functional complementation analysis were carried out to investigate the target gene.

Results

miR-103a-3p was highly expressed in primary NSCLC samples and cell lines. miR-103a-3p mimics promoted the proliferation and invasion of NSCLC cells; miR-103a-3p inhibitor had the opposite effect. A double luciferase reporter gene experiment revealed that miR-103a-3p directly targets the PTEN mRNA 3'UTR region. siPTEN inhibited the proliferation and invasion of NSCLC cells. Further mechanistic studies showed that both overexpression of miR-103a-3p and PTEN knockdown reduced the expression of the p-Akt protein. Overexpression of PTEN partially reversed the cancer-promoting effect of miR-103a-3p.

Conclusion

miR-103a-3p promotes the progression of NSCLC via Akt signaling by targeting PTEN, highlighting the role of miR-103a-3p/PTEN/Akt signaling and suggesting miR-103a-3p as a novel therapeutic target for NSCLC.

Alternative polyadenylation: methods, mechanism, function, and role in cancer

Occurring in over 60% of human genes, alternative polyadenylation (APA) results in numerous transcripts with differing 3'ends, thus greatly expanding the diversity of mRNAs and of proteins derived from a single gene. As a key molecular mechanism, APA is involved in various gene regulation steps including mRNA maturation, mRNA stability, cellular RNA decay, and protein diversification. APA is frequently dysregulated in cancers leading to changes in oncogenes and tumor suppressor gene expressions. Recent studies have revealed various APA regulatory mechanisms that promote the development and progression of a number of human diseases, including cancer. Here, we provide an overview of four types of APA and their impacts on gene regulation. We focus particularly on the interaction of APA with microRNAs, RNA binding proteins and other related factors, the core pre-mRNA 3'end processing complex, and 3'UTR length change. We also describe next-generation sequencing methods and computational tools for use in poly(A) signal detection and APA repositories and databases. Finally, we summarize the current understanding of APA in cancer and provide our vision for future APA related research.

METTL3-mediated maturation of miR-126-5p promotes ovarian cancer progression via PTEN-mediated PI3K/Akt/mTOR pathway

Methyltransferase-like 3 (METTL3) functions as an RNA methyltransferase that controls the modification of N(6)-methyladenosine (m6A) to influence the biosynthesis, decay, and translation of mRNAs. This study aims to investigate the regulation of METTL3-mediated promotion of microRNA-126-5p (miR-126-5p) in the progression of ovarian cancer and to identify the mechanisms in relation to phosphatase and tensin homolog (PTEN) and the PI3K/Akt/mTOR pathway. We found high expression of miR-126-5p in ovarian cancer samples compared to paired adjacent samples, and also in ovarian cancer cell lines. Gain-of-function experiments demonstrated that overexpression of miR-126-5p promoted ovarian cancer cell proliferation, migration, and invasion, and inhibited their apoptosis. Luciferase reporter assay identified that miR-126-5p could directly bind to PTEN. By targeting PTEN, miR-126-5p could activate the PI3K/Akt/mTOR pathway. Furthermore, the RNA methyltransferase METTL3 promoted the maturation of miR-126-5p via the m6A modification of pri-miR-126-5p. Finally, in vitro and in vivo experiments substantiated that silencing of METTL3 impeded the progression and tumorigenesis of ovarian cancer by impairing the miR-126-5p-targeted inhibition of PTEN and thus blocking the PI3K/Akt/mTOR pathway. Coherently, knockdown of METTL3 inhibited the effect of miR-126-5p to upregulate PTEN, and thus prevents PI3K/Akt/mTOR pathway activation, thereby suppressing the development of ovarian cancer. These findings highlight potential targets for the future ovarian cancer treatment as well as tumorigenic mechanisms mediated by m6A modification.

PTEN, a Barrier for Proliferation and Metastasis of Gastric Cancer Cells: From Molecular Pathways to Targeting and Regulation

Cancer is one of the life-threatening disorders that, in spite of excellent advances in medicine and technology, there is no effective cure for. Surgery, chemotherapy, and radiotherapy are extensively applied in cancer therapy, but their efficacy in eradication of cancer cells, suppressing metastasis, and improving overall survival of patients is low. This is due to uncontrolled proliferation of cancer cells and their high migratory ability. Finding molecular pathways involved in malignant behavior of cancer cells can pave the road to effective cancer therapy. In the present review, we focus on phosphatase and tensin homolog (PTEN) signaling as a tumor-suppressor molecular pathway in gastric cancer (GC). PTEN inhibits the PI3K/Akt pathway from interfering with the migration and growth of GC cells. Its activation leads to better survival of patients with GC. Different upstream mediators of PTEN in GC have been identified that can regulate PTEN in suppressing growth and invasion of GC cells, such as microRNAs, long non-coding RNAs, and circular RNAs. It seems that antitumor agents enhance the expression of PTEN in overcoming GC. This review focuses on aforementioned topics to provide a new insight into involvement of PTEN and its downstream and upstream mediators in GC. This will direct further studies for evaluation of novel signaling networks and their targeting for suppressing GC progression.

Long noncoding RNA MAGI1-IT1 promoted invasion and metastasis of epithelial ovarian cancer via the miR-200a/ZEB axis

Epithelial ovarian cancer (EOC) is the most lethal gynecologic malignancy, and its vulnerability to metastasis contributes to the poor outcomes of EOC patients. Long noncoding RNAs (lncRNAs) were verified to play a pivotal role in EOC metastasis. However, the potential role of lncRNA membrane-associated guanylate kinase inverted 1 (MAGI1) intronic transcript (MAGI1-IT1) in EOC is largely unknown. In this study, the function and mechanisms of MAGI1-IT1 in EOC metastasis were explored profoundly. First, MAGI1-IT1 expression was found to be significantly decreased in overexpressing miR-200a EOC cells. Second, MAGI1-IT1 expression was remarkably increased in metastatic EOC tissues, and high MAGI1-IT1 was dramatically associated with EOC FIGO III-IV stage; in addition, MAGI1-IT1 might be related to EOC dissemination via epithelial-mesenchymal transition (EMT). Next, a series of gain- and loss-of-function assays verified that, although MAGI1-IT1 has no significant role in EOC proliferation and subcutaneous xenograft growth, the upregulation of MAGI1-IT1 can remarkably facilitate EOC EMT phenotype, cells migration and invasion ability and intraperitoneal metastasis in nude mice, while downregulation of MAGI1-IT1 led to the opposite effect in vitro. Moreover, MAGI1-IT1 was validated to promote EOC metastasis through upregulation of ZEB1 and ZEB2 by competitively binding miR-200a, and the restrictive effects of MAGI1-IT1 depletion on EOC metastasis could be reversed by inhibition of miR-200a and upregulation of ZEB1 and ZEB2. Collectively, these results suggest that MAGI1-IT1 may work as a ceRNA in promoting EOC metastasis through miR-200a and ZEB1/2 and may be a potential therapeutic target for EOC.