MicroRNA-126-5p Inhibits the Migration of Breast Cancer Cells by Directly Targeting CNOT7

miRNAs Dysregulated in Human Papillomavirus-Associated Benign Prostatic Lesions and Prostate Cancer

Prostate pathologies, including chronic prostatitis, benign prostatic hyperplasia (BPH), and prostate cancer (PCa), are strongly associated with chronic inflammation, which is a key risk factor and hallmark of these diseases [...].

LncRNA MKLN1-AS promotes glioma tumorigenesis and growth via activating the Hippo pathway through miR-126-5p/TEAD1 axis

The involvement of long non-coding RNAs (lncRNAs) in glioma carcinogenesis has gradually been identified. Herein, we aimed to explore the function and mechanism of lncRNA muskelin 1 antisense RNA (MKLN1-AS) in glioma cell oncogenic properties. Quantitative real-time polymerase chain reaction was utilized to test the expression of MKLN1-AS, miR-126-5p, and TEAD1 (TEA Domain Transcription Factor 1) mRNA expression. Oncogenic properties of glioma cells were characterized using 5-ethynyl-2'-deoxyuridine, flow cytometry, wound healing, transwell, and tube formation assays, respectively. Levels of TEAD1 protein, mobility-related proteins, and Hippo pathway-related proteins were examined by Western blotting. The binding between miR-126-5p and MKLN1-AS or TEAD1 was confirmed by using dual-luciferase reporter and pull-down assays. The murine xenograft model was established for in vivo analysis. Levels of MKLN1-AS in glioma tissues and cell lines were higher, functionally, MKLN1-AS deficiency could suppress glioma cell proliferation, migration, invasion, and angiogenesis, and induce apoptosis in vitro, as well as impede tumor growth in vivo. Mechanistically, miR-126-5p was targeted by MKLN1-AS, miR-126-5p directly targeted TEAD1. The suppressing effects of MKLN1-AS deficiency on glioma cell oncogenic properties were abolished by TEAD1 overexpression or miR-126-5p inhibition. Besides, MKLN1-AS/miR-126-5p mediates the activation of Hippo pathway by TEAD1. MKLN1-AS knockdown weakened glioma cell oncogenic phenotypes and growth via TEAD1-Hippo pathway through miR-126-5p, indicating a new therapeutic target for glioma molecular therapy.

Oncogenic Gene CNOT7 Promotes Progression and Induces Poor Prognosis of Glioma

Glioma is the most common malignant brain tumor in the central nervous system with the poor prognosis of patients. The CNOT7 (CCR4-NOT Transcription Complex Subunit 7) is an important functional subunit of CCR4-NOT protein complex that has not been reported in glioma. In this study, we aimed to explore the function of CNOT7 in glioma. The TCGA (The Cancer Genome Atlas) and CGGA (Chinese Glioma Genome Atlas) databases were used for investigating the expression and survival condition of CNOT7 in glioma. The cellular function experiments of qRT-PCR, CCK-8 assays, wound healing assays, and Transwell assays were conducted to verify the function of knockdown CNOT7 in the glioma cell lines DBTRG and U251. Enrichment analysis was used to explore the molecular mechanism of CONT7 in glioma. What is more, the upstream regulation transcription factors of CNOT7 were analyzed based on the ChIP-Atlas and cBioportal (provisional) databases, and verified by the qRT-PCR and luciferase reporter assay. The CNOT7 was highly expressed in glioma and presented the poorer prognosis. The knockdown of CNOT7 inhibited the proliferation, migration, and invasion of glioma cell line, compared to control group. The enrichment analysis revealed that the CNOT7 participated in the development of glioma via G2M checkpoint, E2F targets, IL6-JAK-STAT3, and TNF-α signaling pathways via NF-κB. Besides, it was found that the HDAC2 (Human histone deacetylase-2) contributes to increased CNOT7 expression in glioma. The high-expressed CNOT7 is an oncogene with poor prognosis and participate the progression of glioma.

Targeting the up-regulated CNOT3 reverses therapeutic resistance and metastatic progression of EGFR-mutant non-small cell lung cancer

Lung cancer is the leading cause of cancer-related mortality worldwide. CNOT3, a subunit of the CCR4-NOT complex, has recently been suggested to be overexpressed in lung cancer and involved in tumor malignancy. However, its precise role and the underlying mechanisms still need to be fully revealed. In the present study, we found in lung cancer cells the expression of CNOT3 could be regulated by EGFR signaling pathway and c-Jun, a transcription factor downstream of EGFR, transcriptionally regulated its expression. Interestingly, CNOT3 could inversely regulate the expression of c-Jun via modulating its translation. Thus, a feedback loop existed between c-Jun and CNOT3. CNOT3 reduction post EGFR blockade facilitated the drug-induced cell death, and simultaneously inhibited cell proliferation via impacting TSC1/mTOR axis. Whereas, further up-regulation of the CNOT3 expression was observed in gefitinib-resistant cells, which dampened gefitinib sensitivity. Mechanically, the elevation of CNOT3 was induced by the bypass activation of HER2/c-Jun signaling. Depleting CNOT3 in vitro and in vivo sensitized the drug-resistant cells to gefitinib treatment and inhibited metastatic progression. These results give novel insights into the role of CNOT3 in lung cancer malignancy and provide a theoretical basis for the development of therapeutic strategies to solve acquired resistance to EGFR-TKIs.

ER Negative Breast Cancer and miRNA: There Is More to Decipher Than What the Pathologist Can See!

Breast cancer (BC), the most prevalent cancer in women, is a heterogenous disease. Despite advancements in BC diagnosis, prognosis, and therapeutics, survival rates have drastically decreased in the metastatic setting. Therefore, BC still remains a medical challenge. The evolution of high-throughput technology has highlighted gaps in the classification system of BCs. Of particular interest is the notorious triple negative BC, which was recounted as being heterogenous itself and it overlaps with distinct subtypes, namely molecular apocrine (MA) and luminal androgen (LAR) BCs. These subtypes are, even today, still misdiagnosed and poorly treated. As such, researchers and clinicians have been looking for ways through which to refine BC classification in order to properly understand the initiation, development, progression, and the responses to the treatment of BCs. One tool is biomarkers and, specifically, microRNA (miRNA), which are highly reported as associated with BC carcinogenesis. In this review, the diverse roles of miRNA in estrogen receptor negative (ER-) and androgen receptor positive (AR+) BC are depicted. While highlighting their oncogenic and tumor suppressor functions in tumor progression, we will discuss their diagnostic, prognostic, and predictive biomarker potentials, as well as their drug sensitivity/resistance activity. The association of several miRNAs in the KEGG-reported pathways that are related to ER-BC carcinogenesis is presented. The identification and verification of accurate miRNA panels is a cornerstone for tackling BC classification setbacks, as is also the deciphering of the carcinogenesis regulators of ER - AR + BC.

New oncogenic functions of LINE1 retroelement as a ceRNA for tumor suppressive microRNA miR-126 on ENPP5

Retroelements (REs) had been considered 'Junk' until the encyclopedia of DNA elements (ENCODE) project demonstrated that most genome is functional. Although the function of retroelements has been reported in diverse cancers including human breast cancer (HBC) and subtypes, only a few studies have suggested the putative functions of REs via their random genome integration. A canine mammary tumor (CMT) has been highlighted due to the similarities in molecular and pathophysiology with HBC. This study investigated the putative roles of REs common in both HBC and CMT. The human LINE and HERV-K sequences harbor many miRNAs responsive elements (MREs) for tumor-suppressive miRNA such as let-7. We also observed that various MREs are exist in the ERV and LINE highly expressed in the transcriptome data of CMT as well as HBC sets. MREs against miR-126 were highly expressed in both HBC and CMT while the levels of miR-126 were down-regulated. Oppositely, the expression of miR-126 target genes was significantly up-regulated in the cancers. Moreover, cancer patients with an increased level of miR-126 showed better overall survival. The expression of ENPP5, a putative miR-126 target gene, was downregulated by miR-126 mimic. Importantly, overexpression of LINE fragment significantly suppressed miR-126 function on the target gene expression. We propose the functional role of REs expression in tumorigenesis as competing endogenous RNAs (ceRNA) against tumor-suppressive miRNAs. This study provided pieces of evidence that LINE expression, even partial and fragmented, have a regulatory function in ENPP5 gene expression via the competition with miR-126.

Doxorubicin and Cisplatin Modulate miR-21, miR-106, miR-126, miR-155 and miR-199 Levels in MCF7, MDA-MB-231 and SK-BR-3 Cells That Makes Them Potential Elements of the DNA-Damaging Drug Treatment Response Monitoring in Breast Cancer Cells—A Preliminary Study

One of the most innovative medical trends is personalized therapy, based on simple and reproducible methods that detect unique features of cancer cells. One of the good prognostic and diagnostic markers may be the miRNA family. Our work aimed to evaluate changes in selected miRNA levels in various breast cancer cell lines (MCF7, MDA-MB-231, SK-BR-3) treated with doxorubicin or cisplatin. The selection was based on literature data regarding the most commonly altered miRNAs in breast cancer (21-3p, 21-5p, 106a-5p, 126-3p, 126-5p, 155-3p, 155-5p, 199b-3p, 199b-5p, 335-3p, 335-5p). qPCR assessment revealed significant differences in the basal levels of some miRNAs in respective cell lines, with the most striking difference in miR-106a-5p, miR-335-5p and miR-335-3p—all of them were lowest in MCF7, while miR-153p was not detected in SK-BR-3. Additionally, different alterations of selected miRNAs were observed depending on the cell line and the drug. However, regardless of these variables, 21-3p/-5p, 106a, 126-3p, 155-3p and 199b-3p miRNAs were shown to respond either to doxorubicin or to cisplatin treatment. These miRNAs seem to be good candidates for markers of breast cancer cell response to doxorubicin or cisplatin. Especially since some earlier reports suggested their role in affecting pathways and expression of genes associated with the DNA-damage response. However, it must be emphasized that the preliminary study shows effects that may be highly related to the applied drug itself and its concentration. Thus, further examination, including human samples, is required.

MicroRNAs: A Link between Mammary Gland Development and Breast Cancer

Breast cancer is among the most common cancers in women, second to skin cancer. Mammary gland development can influence breast cancer development in later life. Processes such as proliferation, invasion, and migration during mammary gland development can often mirror processes found in breast cancer. MicroRNAs (miRNAs), small, non-coding RNAs, can repress post-transcriptional RNA expression and can regulate up to 80% of all genes. Expression of miRNAs play a key role in mammary gland development, and aberrant expression can initiate or promote breast cancer. Here, we review the role of miRNAs in mammary development and breast cancer, and potential parallel roles. A total of 32 miRNAs were found to be expressed in both mammary gland development and breast cancer. These miRNAs are involved in proliferation, metastasis, invasion, and apoptosis in both processes. Some miRNAs were found to have contradictory roles, possibly due to their ability to target many genes at once. Investigation of miRNAs and their role in mammary gland development may inform about their role in breast cancer. In particular, by studying miRNA in development, mechanisms and potential targets for breast cancer treatment may be elucidated.

The Polymorphism and Expression of EGFL7 and miR-126 Are Associated With NSCLC Susceptibility

Previous investigations have reported that microRNA-126 (miR-126) and its host gene, epidermal growth factor-like domain-containing protein 7 (EGFL7) are involved in lung cancer progression, suggesting EGFL7 and miR-126 play a joint role in lung cancer development. In this study, we analyzed the methylation-associated regulation of EGFL7 and miR-126 in non-small cell lung cancer (NSCLC) and further investigated the association between EGFL7/miR-126 polymorphisms and NSCLC susceptibility in the Han Chinese population. Based on our data, relative to those in adjacent normal tissue, both EGFL7 expression and miR-126 expression were decreased significantly in lung cancer tissue (P = 3x10^-4 and P < 1x10^-4), and the expression of EGFL7 mRNA and miR-126 was significantly correlated in both NSCLC tissue n = 46, r = 0.43, P = 0.003 and adjacent normal tissue n = 46, r = 0.37, P = 0.011. Differential methylation analysis indicated that methylation levels of multiple CG loci in EGFL7 were significantly higher in the lung cancer samples than in the normal samples (P < 0.01). Moreover, EGFL7 mRNA and miR-126 were significantly upregulated after treatment with the DNA demethylating agent 5-aza-2′-deoxycytidine (5-Aza-CdR) in lung cancer cell lines. In addition, the A allele of rs2297538 was significantly associated with a decreased NSCLC risk (OR = 0.68, 95% CI: 0.52~0.88), and the expression of EGFL7 and miR-126 was significantly lower in rs2297538 homozygous G/G tumor tissue than in A/G+A/A tumor tissue (P = 0.01 and P = 0.002). Our findings suggest that the expression of EGFL7 and miR-126 in NSCLC can be concomitantly downregulated through methylation and the EGFL7/miR-126 polymorphism rs2297538 is correlated with NSCLC risk. Together, these results provide new insights into the pathogenesis of NSCLC.

Methylation recognition protein YTH N6-methyladenosine RNA binding protein 1 (YTHDF1) regulates the proliferation, migration and invasion of osteosarcoma by regulating m6A level of CCR4-NOT transcription complex subunit 7 (CNOT7)

N6-methyladenosine (m6A) is one of the most significant modifications in human mRNAs. Emerging evidence indicates that m6A participates in the initiation and development of malignant tumors. Nevertheless, the biological roles and mechanism of m6A in osteosarcoma (OS) remain unclear. The purpose of this study was to investigate the role and mechanism of the methylation recognition protein-YTH N6-methyladenosine RNA binding protein 1 (YTHDF1) in OS. The YTHDF1 expression in OS was detected by qRT-PCR and Western blot assay. M6A quantification was utilized to measure the methylation level of OS. Cell counting kit-8 (CCK8), 5-Ethynyl-2’-deoxyuridine (EdU) assay and transwell experiments were conducted to confirm the biological effects of YTHDF1 on OS cells. The bioinformatics websites and in vitro assays were conducted to analyze the downstream targets of YTHDF1 was upregulated in OS tissues at mRNA and protein level. The results showed that the expression level of YTHDF1 might be closely associated with the poor prognosis for OS patients. Inhibition of YTHDF1 could suppress the proliferation, migration and invasion of the OS cells. Moreover, we found that CCR4-NOT transcription complex subunit 7 (CNOT7) might be the potential target of YTHDF1, which was upregulated in OS tissues. YTHDF1 could recognize the m6A sites of CONT7 and promote its expression in an m6A manner. Moreover, methyltransferase-like 3 (METTL3) could promote the m6A level of CONT7. YTHDF1 was upregulated in OS and could promote cell proliferation, migration and invasion. The METTL3-CONT7-YTHDF1 regulatory axis might be the potential target for the prognosis and therapy of OS.

MiR-126-5p Promotes Tumor Cell Proliferation, Metastasis and Invasion by Targeting TDO2 in Hepatocellular Carcinoma

TDO2 is a key enzyme in the kynurenine metabolic pathway, which is the most important pathway of tryptophan metabolism. It has been shown that miRNAs are involved in cell metastasis through interaction with target mRNAs. In this study, we found 645 miRNAs that could be immunoprecipitated with TDO2 through the RNA-immunoprecipitation experiment. miR-126-5p was selected as the research target, which was also confirmed by dual-luciferase reporter assay. Through qRT-PCR analysis, it was verified that the overexpression of miR-126-5p promoted the expression of TDO2, PI3K/AKT and WNT1. Meanwhile, it was verified that overexpression of miR-126-5p can promote intracellular tryptophan metabolism by HPLC. We also verified the effects of miR-126-5p on cell proliferation, migration, and invasion by cck-8, cell colony formation and trans-well assay in both HCCLM3 cells and HepG2 cells. In vivo experiments were also conducted to verify that miR-126-5p promoted tumor formation and growth via immunohistochemical detection of cell infiltration and proliferation to generate markers Ki-67, BAX, and VEGF. In conclusion, our results suggest that miR-126-5p is a biomarker and a potential new treatment target in the progression of HCC via promoting the expression of TDO2.