Deregulation of miR-520d-3p promotes hepatocellular carcinoma development via lncRNA MIAT regulation and EPHA2 signaling activation

Novel role of lncRNAs regulatory network in papillary thyroid cancer

Papillary thyroid cancer (PTC) is the most common endocrine malignancy. The incidence of PTC has increased annually worldwide. Thus, PTC diagnosis and treatment attract more attention. Noncoding RNAs (lncRNAs) play crucial roles in PTC progression and act as prognostic biomarkers. Moreover, microRNAs (miRNAs) and epithelial-mesenchymal transition (EMT)-associated proteins have potential biomarkers for diagnosing and treating PTC. However, the correlation of lncRNAs with miRNAs and EMT-associated proteins needs further clarification. The present review highlights the recent advances of lncRNAs in PTC. We significantly summarized the two molecular regulatory mechanisms in PTC progress, including lncRNAs-miRNAs-protein signaling axes and lncRNAs-EMT pathways. This review will help our understanding of the association between lncRNAs and PTC and may assist us in evaluating the prognosis for PTC patients. Taken together, targeting the lncRNAs regulatory network has promising applications in diagnosing and treating PTC.

Puzzling out the role of MIAT LncRNA in hepatocellular carcinoma

A non-negligible part of our DNA has been proven to be transcribed into non-protein coding RNA and its intricate involvement in several physiological processes has been highly evidenced. The significant biological role of non-coding RNAs (ncRNAs), including long non-coding RNAs (lncRNAs) has been variously reported. In the current review, the authors highlight the multifaceted role of myocardial infarction-associated transcript (MIAT), a well-known lncRNA, in hepatocellular carcinoma (HCC). Since its discovery, MIAT has been described as a regulator of carcinogenesis in several malignant tumors and its overexpression predicts poor prognosis in most of them. At the molecular level, MIAT is closely linked to the initiation of metastasis, invasion, cellular migration, and proliferation, as evidenced by several in-vitro and in-vivo models. Thus, MIAT is considered a possible theranostic agent and therapeutic target in several malignancies. In this review, the authors provide a comprehensive overview of the underlying molecular mechanisms of MIAT in terms of its downstream target genes, interaction with other classes of ncRNAs, and potential clinical implications as a diagnostic and/or prognostic biomarker in HCC.

Investigation into the Role of Long-Non-Coding RNA MIAT in Leukemia

Myocardial Infarction Associated Transcript (MIAT) is a nuclear long non-coding RNA (LncRNA) with four different splicing variants. MIAT dysregulation is associated with carcinogenesis, mainly acting as an oncogene regulating cellular growth, invasion, and metastasis. The aim of the current study is to investigate the role of MIAT in the regulation of T and chronic myeloid leukemic cell survival. To this end, MIAT was silenced using MIAT-specific siRNAs in leukemic cell lines, and functional assays were performed thereafter. This investigation also aims to investigate the effects of MIAT silencing on the expression of core genes involved in cancer. Functional studies and gene expression determination confirm that MIAT knockdown not only affects short- and long-term survival and the apoptosis of leukemic cells but also plays a pivotal role in the alteration of key genes involved in cancer, including c-MYC and HIF-1A. Our observations suggest that MIAT could act as an oncogene and it has the potential to be used not only as a reliable biomarker for leukemia, but also be employed for prognostic and therapeutic purposes.

MiR-520d-3p suppresses the proliferation and epithelial-mesenchymal transition of cervical cancer cells by targeting ZFP36L2

MiR-520d-3p has recently been reported to have anti-tumor function in several cancers, including glioma and gastric cancer. However, the biological function and its mechanism of action remain unclear in cervical cancer (CC). In this study, we observed that miR-520d-3p expression was lowly expressed in CC specimens compared with adjacent normal specimens using reverse transcription quantitative PCR. Moreover, low miR-520d-3p expression was correlated with FIGO stage and lymph node metastasis by Chi-square test. Functionally, overexpression of miR-520d-3p suppressed the proliferation and migration and invasion of two CC cell lines (HeLa and SiHa) using CCK-8 assay and wound healing assay. After target prediction, luciferase reporter assay showed that zinc finger protein 36 ring finger protein-like 2 (ZFP36L2) was a direct target of miR-520d-3p in CC cells. The expression levels of ZFP36L2 at protein and mRNA were significantly increased in CC tissues compared with adjacent tissues. The expression of ZFP36L2 was negatively correlated with miR-520d-3p in the patients with CC. Importantly, ZFP36L2 overexpression abolished the effects of miR-520d-3p on cell proliferation, migration and EMT process in CC cells. In conclusion, our findings indicate that targeting miR-520d-3p/ZFP36L2 axis might be a promising therapeutic target for CC treatment.

Unraveling the Significance of EPH/Ephrin Signaling in Liver Cancer: Insights into Tumor Progression and Therapeutic Implications

Liver cancer is a complex and challenging disease with limited treatment options and dismal prognosis. Understanding the underlying molecular mechanisms driving liver cancer progression and metastasis is crucial for developing effective therapeutic strategies. The EPH/ephrin system, which comprises a family of cell surface receptors and their corresponding ligands, has been implicated in the pathogenesis of HCC. This review paper aims to provide an overview of the current understanding of the role of the EPH/ephrin system in HCC. Specifically, we discuss the dysregulation of EPH/ephrin signaling in HCC and its impact on various cellular processes, including cell proliferation, migration, and invasion. Overall, the EPH/ephrin signaling system emerges as a compelling and multifaceted player in liver cancer biology. Elucidating its precise mechanisms and understanding its implications in disease progression and therapeutic responses may pave the way for novel targeted therapies and personalized treatment approaches for liver cancer patients. Further research is warranted to unravel the full potential of the EPH/ephrin system in liver cancer and its clinical translation.

LncRNA PROX1 antisense RNA 1 promotes PD-L1-mediated proliferation, metastasis, and immune escape in colorectal cancer by interacting with miR-520d

It was recently found that lncRNA PROX1 antisense RNA 1 (PROX1-AS1) manifested oncogenicity in a variety of malignancies. This work intended to investigate the molecular mechanisms of PROX1-AS1 in colorectal cancer (CRC) development and immune evasion. In this study, both PROX1-AS1 and PD-L1 expressions were lifted in CRC tissues and cells. PROX1-AS1 interference restrained CRC cell proliferation, migration, invasion, as well as CD8 + T-lymphocyte apoptosis, but increased the cytotoxicity and percentage of CD8 + T lymphocytes. The inhibitory effects of PROX1-AS1 inhibition on CRC progression and immune escape were positively related to PD-L1 suppression. PROX1-AS1 absorbed miR-520d to upregulate PD-L1 expression. PROX1-AS1 facilitated CRC progression and immune escape by targeting miR-520d. Furthermore, PROX1-AS1 deletion impaired CRC tumor growth in vivo . To sum up, this study affirmed that PROX1-AS1 could absorb miR-520d to upregulate PD-L1 in CRC, thereby promoting tumor progression and immune escape.

Comparison of Oncogenes, Tumor Suppressors, and MicroRNAs Between Schizophrenia and Glioma: The Balance of Power

The risk of cancer in schizophrenia has been controversial. Confounders of the issue are cigarette smoking in schizophrenia, and antiproliferative effects of antipsychotic medications. The author has previously suggested comparison of a specific cancer like glioma to schizophrenia might help determine a more accurate relationship between cancer and schizophrenia. To accomplish this goal, the author performed three comparisons of data; the first a comparison of conventional tumor suppressors and oncogenes between schizophrenia and cancer including glioma. This comparison determined schizophrenia has both tumor-suppressive and tumor-promoting characteristics. A second, larger comparison between brain-expressed microRNAs in schizophrenia with their expression in glioma was then performed. This identified a core carcinogenic group of miRNAs in schizophrenia offset by a larger group of tumor-suppressive miRNAs. This proposed "balance of power" between oncogenes and tumor suppressors could cause neuroinflammation. This was assessed by a third comparison between schizophrenia, glioma and inflammation in asbestos-related lung cancer and mesothelioma (ALRCM). This revealed that schizophrenia shares more oncogenic similarity to ALRCM than glioma.

The LncRNA MIAT is identified as a regulator of stemness-associated transcript in glioma

BACKGROUND

Myocardial infarction-associated transcript (MIAT) is a long non-coding RNA (lncRNA) with altered expression in different diseases and malignancies. In this study, the potential expression and function of lncRNA MIAT in intuition and progression of brain cancer was investigated.

METHODS AND RESULTS

At first, TCGA data analysis demonstrated that lncRNA MIAT is significantly upregulated in various malignancies, especially its expression is dramatically elevated in brain tumors. In line with the data, we further evaluated the expression of MIAT in a series of brain tumor tissue, and our results revealed that the expression of MIAT was noticeably overexpressed in glioblastoma (p = < 0.0001). We further found that the expression of MIAT was markedly upregulated in low-grade brain tumors rather than high-grade ones. To further investigate the biological function of MIAT in brain cancer cells, its expression was suppressed by si-RNA-mediated knocking down. Inhibition of MIAT resulted in reduced proliferation of brain tumor cells followed by cell cycle arrest at the G1 phase, and significant induction of apoptosis, and senescence, but limited the migration ability and epithelial-mesenchymal-transition (EMT). Moreover, knocking-down of MIAT reduced the expression of stemness factors, followed by upregulation of their downstream miRNAs (micro RNAs), let-7a-5p, and miR-29b-3p.

CONCLUSIONS

Altogether, our data demonstrated that lncRNA MIAT could control proliferation, migration, and metastasis of brain cancer cells via regulating the Nanog/ Sox2 / let-7a-5p / miR-29b-3p axis. This data could introduce lncRNA MIAT as a novel oncogene in brain cancer pathogenesis.

Lipofectamine 2000™ at transfection dose promotes EphA2 transcription in an HDAC4-dependent manner to reduce its cytotoxicity

The cationic liposome is well-known as an efficient nucleic acid delivery tool; however, the stress responses induced by liposome per se have been rarely revealed. In this study, we found that Lipofectamine™ 2000 (lipo2000), a commonly used commercial cationic liposome transfection, could upregulate EphA2 mRNA expression in multiple cells at transfection dose. Furthermore, lipo2000 treatment could increase the level of EphA2 hnRNA (heterogeneous nuclear RNA). Lipo2000-induced EphA2 upregulation could be depleted upon global transcription inhibition, proving that lipo2000 upregulates EphA2 expression via activating its transcription. Moreover, HDAC4 depletion, a known EphA2 trans-acting regulatory factor, could eliminate the lipo2000-induced EphA2 upregulation, demonstrating that lipo2000 promotes EphA2 transcription in an HDAC4 dependent manner. Functionally, EphA2 knockdown did not affect GFP expression level and the interfering efficacy of siGAPDH, suggesting that EphA2 is unrelated to the nucleic acid delivery capacity of lipo2000. Nevertheless, EphA2 depletion significantly activated autophagy and apoptosis, increasing the cytotoxic effects of lipo2000, which could be rescued by EphA2 restoration, indicating that EphA2 is essential to overcome liposome-related cytotoxicity. Finally, we found that lipo2000 could activate EphA2 transcription in an HDAC4-dependent manner. EphA2 is not associated with the transfection efficiency of lipo2000, but it is vital to reduce lipo2000 cytotoxicity, suggesting that when conducting liposome-mediated gene function studies, especially for EphA2, the stress response of liposomes should be considered to obtain objective results.

HOXA cluster antisense RNA 2 elevates KIAA1522 expression through microRNA-520d-3p and insulin like growth factor 2 mRNA binding protein 3 to promote the growth of vascular smooth muscle cells in thoracic aortic aneurysm

AIMS

Recently, long non-coding RNAs (lncRNAs) have been revealed to mediate smooth muscle dysfunction in thoracic aortic aneurysm (TAA). LncRNA HOXA-AS2 has been proposed to engage in the regulation of diverse diseases. However, its function in TAA remains unknown. This study aimed to reveal the role and mechanism of HOXA-AS2 in VSMCs which were implicated in TAA formation.

METHODS AND RESULTS

RT-qPCR or western blot was performed to detect RNA or protein expression levels. The role of HOXA-AS2 in VSMCs was explored by functional assays. The relationship among HOXA-AS2/miR-520d-3p/KIAA1522/IGF2BP3 was analysed via mechanism assays. HOXA-AS2 was detected to have significantly high expression in TAA tissues and function as an oncogene to promote proliferation of VSMCs, while inhibiting cell apoptosis (Figure 1, **P < 0.01). HOXA-AS2 was unveiled to bind with miR-520d-3p (Figure 2, *P < 0.05, **P < 0.01) and further up-regulate KIAA1522 to facilitate the growth of VSMCs (Figure 3-4, *P < 0.05, **P < 0.01). HOXA-AS2 was also found to recruit IGF2BP3 to stabilize KIAA1522 mRNA (Figure 5, **P < 0.01). All data were displayed as mean ± standard deviation.

CONCLUSIONS

HOXA-AS2 up-regulates KIAA1522 through targeting miR-520d-3p/IGF2BP3 to drive VSMC growth in TAA.

MicroRNA-520d-3p suppresses melanoma cells proliferation by inhibiting the anti-silencing function 1B histone chaperone

As the most common and aggressive malignant form of skin cancer, melanoma has a poor prognosis in its late stage. MicroRNA (miR)-520d-3p has been reported as a key modulator that regulates the development of different types of cancer, but its role in melanoma remains unclear. The purpose of this study was to investigate the role and mechanism of miR-520d-3p in melanoma. The expression of anti-silencing function 1B histone chaperone (ASF1B) and miR-520d-3p in melanoma tissues and cells was detected by reverse transcription-quantitative polymerase chain reaction. The interaction between ASF1B and miR-520d-3p was verified by luciferase activity detection. Cell counting kit-8, bromodeoxyuridine, fluorescein isothiocyanate, and cell adhesion assays were performed to detect cell viability, proliferation, apoptosis, and adhesion in melanoma cells. ASF1B expression was evidently increased, whereas miR-520d-3p level was downregulated in melanoma tissues and cells. Overexpression of ASF1B enhanced cell growth and adhesion and hampered cell apoptosis in melanoma cells. Furthermore, miR-520d-3p suppressed the tumorigenic effects of melanoma cells. Moreover, miR-520d-3p suppressed the expression of ASF1B to suppress melanoma tumorigenesis. In conclusion, we have found out that miR-520d-3p suppressed melanoma tumorigenesis by inhibiting ASF1B, which could be a promising target for melanoma therapy.

Heterogeneous graph attention network based on meta-paths for lncRNA-disease association prediction

MOTIVATION

Discovering long noncoding RNA (lncRNA)-disease associations is a fundamental and critical part in understanding disease etiology and pathogenesis. However, only a few lncRNA-disease associations have been identified because of the time-consuming and expensive biological experiments. As a result, an efficient computational method is of great importance and urgently needed for identifying potential lncRNA-disease associations. With the ability of exploiting node features and relationships in network, graph-based learning models have been commonly utilized by these biomolecular association predictions. However, the capability of these methods in comprehensively fusing node features, heterogeneous topological structures and semantic information is distant from optimal or even satisfactory. Moreover, there are still limitations in modeling complex associations between lncRNAs and diseases.

RESULTS

In this paper, we develop a novel heterogeneous graph attention network framework based on meta-paths for predicting lncRNA-disease associations, denoted as HGATLDA. At first, we conduct a heterogeneous network by incorporating lncRNA and disease feature structural graphs, and lncRNA-disease topological structural graph. Then, for the heterogeneous graph, we conduct multiple metapath-based subgraphs and then utilize graph attention network to learn node embeddings from neighbors of these homogeneous and heterogeneous subgraphs. Next, we implement attention mechanism to adaptively assign weights to multiple metapath-based subgraphs and get more semantic information. In addition, we combine neural inductive matrix completion to reconstruct lncRNA-disease associations, which is applied for capturing complicated associations between lncRNAs and diseases. Moreover, we incorporate cost-sensitive neural network into the loss function to tackle the commonly imbalance problem in lncRNA-disease association prediction. Finally, extensive experimental results demonstrate the effectiveness of our proposed framework.

The expression and diagnostic value of serum levels of EphA2 and VEGF-A in patients with colorectal cancer

BACKGROUND

Several molecules are highly expressed in the serum of cancer patients, and can be used as serological markers. This approach has become one of the important auxiliary diagnostic methods for cancer.

AIM

To investigate the correlation between the serum levels of EphA2 and VEGF-A and the pathogenesis of colorectal cancer (CRC) as well as the potential value of these molecules in the diagnosis of CRC.

METHODS

ELISA was used to detect the levels of EphA2 and VEGF-A in the peripheral venous serum of 106 newly diagnosed patients with CRC and 69 normal controls. The relationship between the serum EphA2 and VEGF-A levels and the clinicopathological characteristics of CRC patients was analyzed. ROC analysis was used to investigate the diagnostic value of the serum EphA2 and VEGF-A levels in CRC, and the optimal cutoff value was calculated.

RESULTS

The serum levels of EphA2 and VEGF-A in the CRC group were higher than those in the control as well as CEA, the serum level of EphA2 was positively correlated with the VEGF-A levels, but neither was significantly associated with the clinicopathological parameters of CRC. The ROC curve showed that the single index AUC was < 0.7 except for VEGF-A, and the accuracy of the combined diagnosis was higher than that of any other single index. The diagnosis scheme involving all three markers was the best (the sensitivity was 60.40%, the specificity was 92.8%, and the accuracy was 53.1%). The best critical values calculated were EphA2 > 297.92 ng/ml, EphA2 > 183.92 pg/ml and CEA > 5.19 ng/ml.

CONCLUSION

The serum levels of EphA2 and VEGF-A are high in CRC patients, and the combine detection of CEA, EphA2 and VEGF-A can significantly improve the diagnostic accuracy of CRC.

MIAT Is an Upstream Regulator of NMYC and the Disruption of the MIAT/NMYC Axis Induces Cell Death in NMYC Amplified Neuroblastoma Cell Lines

Neuroblastoma (NBL) is the most common extracranial childhood malignant tumor and represents a major cause of cancer-related deaths in infants. NMYC amplification or overexpression is associated with the malignant behavior of NBL tumors. In the present study, we revealed an association between long non-coding RNA (lncRNA) myocardial infarction associated transcript (MIAT) and NMYC amplification in NBL cell lines and MIAT expression in NBL tissue samples. MIAT silencing induces cell death only in cells with NMYC amplification, but in NBL cells without NMYC amplification it decreases only the proliferation. MIAT downregulation markedly reduces the NMYC expression in NMYC-amplified NBL cell lines and c-Myc expression in NMYC non-amplified NBL cell lines, but the ectopic overexpression or downregulation of NMYC did not affect the expression of MIAT. Moreover, MIAT downregulation results in decreased ornithine decarboxylase 1 (ODC1), a known transcriptional target of MYC oncogenes, and decreases the glycolytic metabolism and respiratory function. These results indicate that MIAT is an upstream regulator of NMYC and that MIAT/NMYC axis disruption induces cell death in NMYC-amplified NBL cell lines. These findings reveal a novel mechanism for the regulation of NMYC in NBL, suggesting that MIAT might be a potential therapeutic target, especially for those with NMYC amplification.

Targeting EphA2 suppresses hepatocellular carcinoma initiation and progression by dual inhibition of JAK1/STAT3 and AKT signaling

Hepatocellular carcinoma (HCC) remains one of the deadliest malignancies worldwide. One major obstacle to treatment is a lack of effective molecular-targeted therapies. In this study, we find that EphA2 expression and signaling are enriched in human HCC and associated with poor prognosis. Loss of EphA2 suppresses the initiation and growth of HCC both in vitro and in vivo. Furthermore, CRISPR/CAS9-mediated EphA2 inhibition significantly delays tumor development in a genetically engineered murine model of HCC. Mechanistically, we discover that targeting EphA2 suppresses both AKT and JAK1/STAT3 signaling, two separate oncogenic pathways in HCC. We also identify a small molecule kinase inhibitor of EphA2 that suppresses tumor progression in a murine HCC model. Together, our results suggest EphA2 as a promising therapeutic target for HCC.

miR-520d suppresses rapid pacing-induced apoptosis of atrial myocytes through mediation of ADAM10

MicroRNAs (miRNAs) play a key role in various pathological processes like atrial fibrillation (AF). However, the mechanisms remain unclear. Herein, this study was undertaken to probe the roles of ADAM10 and its targeting miR-520d in rapid pacing-induced apoptosis in atrial myocytes. In this study, the atrial myocytes grew adherently with irregular morphology. Immunofluorescence showed that more than 90% of atrial myocytes were α-sarcomeric actin (α-SCA) positive, indicating that the primary cells were positive for α-SCA staining and atrial myocytes were successfully isolated. The pacing atrial myocyte model was established after rapid pacing stimulation and we found the rapid pacing stimulation caused elevated ADAM10 and suppressed miR-520d. CCK-8 assay was applied for evaluation of cell viability, TUNEL staining for assessment of cell apoptosis and dual-luciferase reporter gene assay for verification of the targeting relationship between miR-520d and ADAM10. Overexpression of miR-520d or silencing of ADAM10 could enhance cell viability and reduce cell apoptosis in the rapid pacing-induced atrial myocytes. ADAM10 was a target gene of miR-520d. MiR-520d negatively targeted ADAM10, thereby promoting cell viability and inhibiting apoptosis in rapid pacing atrial myocyte model. In summary, miR-520d enhances atrial myocyte viability and inhibits cell apoptosis in rapid pacing-induced AF mouse model through negative mediation of ADAM10.

MicroRNA-520d-3p alleviates hypoxia/reoxygenation-induced damage in human cardiomyocytes by targeting ATG-12

Hypoxia/reoxygenation (H/R) induced injury results in extensive damages to myocardial tissue in patients with coronary heart disease, which leads to heart failure. MicroRNA (miRNA) is thought to be associated with myocardial H/R injury. The purpose of this study was to investigate the in vitro role of microRNA-520d-3p in human myocardial cell (HCM) myocardial H/R injury. MTT method and Annexin V-FITC flow cytometry were employed to measure the viability and apoptosis of H/R treated HCM. RT-qPCR was employed to determine miRNA and mRNA expression. MicroRNA-520d-3p mimic and microRNA-520d-3p inhibitor were used to overexpression and inhibit the expression of microRNA-520d-3p. In addition, pcDNA3.1-ATG12 was used to upregulate ATG12 expression. The protein levels of ATG12, Bcl-2 and autophagy related-genes were determined by western blotting. Hypoxia/reoxygenation (H/R) injury could inhibit cell viability, apoptosis and inhibited microRNA-520d-3p expression in HCM. The down-regulation of microRNA-520d-3p inhibited cell viability and induced apoptosis in HCM. The overexpression of microRNA-520d-3p attenuated the effects of H/R treatment on the viability and apoptosis of HCM cells. In addition, microRNA-520d-3p inhibited the expression of autophagy-associated 12 (ATG12). More importantly, H/R treatment could promote autophagy in HCM, and microRNA-520d-3p mimic transfection could significantly reverse this effect. Our result indicated that overexpression of microRNA-520d-3p attenuated the effect of H/R treatments on cell viability, apoptosis and autophagy, through partly regulating ATG12 expression in HCM.

Emerging Role and Therapeutic Potential of lncRNAs in Colorectal Cancer

Maintenance of the intestinal epithelium is dependent on the control of stem cell (SC) proliferation and differentiation. The fine regulation of these cellular processes requires a complex dynamic interplay between several signaling pathways, including Wnt, Notch, Hippo, EGF, Ephrin, and BMP/TGF-β. During the initiation and progression of colorectal cancer (CRC), key events, such as oncogenic mutations, influence these signaling pathways, and tilt the homeostatic balance towards proliferation and dedifferentiation. Therapeutic strategies to specifically target these deregulated signaling pathways are of particular interest. However, systemic blocking or activation of these pathways poses major risks for normal stem cell function and tissue homeostasis. Interestingly, long non-coding RNAs (lncRNAs) have recently emerged as potent regulators of key cellular processes often deregulated in cancer. Because of their exceptional tissue and tumor specificity, these regulatory RNAs represent attractive targets for cancer therapy. Here, we discuss how lncRNAs participate in the maintenance of intestinal homeostasis and how they can contribute to the deregulation of each signaling pathway in CRC. Finally, we describe currently available molecular tools to develop lncRNA-targeted cancer therapies.

Myocardial Infarction Associated Transcript (MIAT): Review of its impact in the tumorigenesis

Myocardial Infarction Associated Transcript (MIAT) is a non-coding transcript which is located on chromosome 22q12.1. This lncRNA can regulate expression of genes at both transcriptional and post-transcriptional stages. It has been firstly recognized as a susceptibility locus for myocardial infarction. Subsequently, its role in the development of several human cancers has been acknowledged. Numerous researches have reported the impact of MIAT silencing on the reduction of cell viability, proliferation and invasion while enhancement of cellular senescence and apoptosis. Consistently, investigations in the xenograft models have verified MIAT role in the promotion of tumor growth. Numerous microRNAs such as miR-214, miR-22-3p, miR-520d-3p, miR-203a, miR-29a-3p, miR-141, miR-150, miR-302, miR-29, and miR-155-5p have functional interactions with this lncRNA. Moreover, dysregulation of MIAT has been associated with abnormal activity of numerous cancer-related signaling cascades such as Hippo, PI3K/Akt/c-Met and Wnt/β-catenin. In the current review, we explain the role of MIAT in the cancer evolution based on the outcomes of in vitro, in vivo and clinical studies.

LncRNA MIAT correlates with immune infiltrates and drug reactions in hepatocellular carcinoma

Long non-coding RNA (lncRNA) is a kind of important molecules involved in the formation of immune landscape in tumor microenvironment. However, there are few studies on the relationship between lncRNA and immunomodulatory regulation of hepatocellular carcinoma (HCC). In this study, we combined with single cell transcriptome sequencing and TCGA data to analyze the relationship between lncRNA MIAT and immune cells in HCC. TIMER database analysis indicated that the expression of MIAT in HCC was negatively correlated with tumor purity, positively correlated with the number of immune cells such as B cells, T lymphocytes and macrophages, and positively correlated with the expression of immune checkpoint molecules such as PD-1, PD-L1 and CTLA4. Analysis of single cell sequencing data of immune cells in HCC showed that MIAT was mainly distributed in tumor, and enriched in FOXP3⁺CD4⁺T cells and PDCD1⁺CD8⁺, GZMK⁺CD8⁺T cells, indicating that MIAT may be involved in the immune escape process of HCC. Besides, through the construction of transcription factor (TF) regulatory network, MIAT-TF-mRNA, we found that the interaction of MIAT and TFs may affect the immune microenvironment of LIHC by regulating the expression of target genes JAK2, SLC6A6, KCND1, MEIS3 or RIN1; LncMAP and CARE analysis showed that MIAT was highly related to the sensitivity of many anticancer drugs, especially sorafenib. In addition, the effect of MIAT on PD-L1 and its relationship with sorafinib were verified in clinical specimens and cells. This study made a meaningful attempt to reveal the immune escape mechanism and to find the effectiveness of targeted drugs in patients with HCC.

LNA Inhibitor in microRNA miR-23b as a Potential Anti-proliferative Option in Human Hepatocellular Carcinoma

PURPOSE

Dysregulation of microRNAs (miRNAs) has been shown to be involved in the pathogenesis and progression of many malignancies. Human hepatocellular carcinoma (HCC) is one of the most common cancers worldwide and the third cause of cancer-related deaths. Recent data suggest that microRNA-23b (miR-23b) is significantly high in different types of cancer, specifically human hepatocellular carcinoma. Locked nucleic acid (LNA)-modified oligonucleotides have recently been suggested as a novel approach for targeting miRNAs as antisense-based gene silencing. The aim of this study was to explore the functional role of LNA-anti-miR-23b in a HepG2 (hepatocarcinoma) cell line.

METHODS

HepG2 cells were transfected with LNA-anti-miR-23b for 24, 48, and 72 h. Quantitative real-time reverse transcriptase-PCR (qRT-PCR) was performed to assess miR-23b expression by LNA-anti-miR-23b. The viability of the cells was evaluated by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) assay.

RESULTS

LNA-anti-miR-23b was successfully transfected into human HepG2 cells and suppressed the miR-23b. LNA-anti-miR-23b reduced the invasive behaviors of HepG2 cells after 24 h, compared to untreated cells and scrambled LNA-transfected cells, and this effect was more pronounced after 72 h.

CONCLUSIONS

Our findings suggest that inhibition of miR-23b could be used as a novel approach in inhibition of HCC proliferation.

Epigenetic Associations between lncRNA/circRNA and miRNA in Hepatocellular Carcinoma

Simple Summary

Non-coding RNAs such as microRNAs, long non-coding RNAs, and circular RNAs contribute to the development and progression of hepatocellular carcinoma through epigenetic association. Long non-coding RNAs and circular RNAs act as competing endogenous RNAs that contain binding sites for miRNAs and thus compete with the miRNAs, which results in promotion of miRNA target gene expression, thereby leading to proliferation and metastasis of hepatocellular carcinoma. Competing endogenous RNAs have the potential to become diagnostic biomarkers and therapeutic targets for treatment of hepatocellular carcinoma.

Abstract

The three major members of non-coding RNAs (ncRNAs), named microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), play an important role in hepatocellular carcinoma (HCC) development. Recently, the competing endogenous RNA (ceRNA) regulation model described lncRNA/circRNA as a sponge for miRNAs to indirectly regulate miRNA downstream target genes. Accumulating evidence has indicated that ceRNA regulatory networks are associated with biological processes in HCC, including cancer cell growth, epithelial to mesenchymal transition (EMT), metastasis, and chemoresistance. In this review, we summarize recent discoveries, which are specific ceRNA regulatory networks (lncRNA/circRNA-miRNA-mRNA) in HCC and discuss their clinical significance.

MicroRNA-587 Functions as a Tumor Suppressor in Hepatocellular Carcinoma by Targeting Ribosomal Protein SA

Background

Hepatocellular carcinoma (HCC) is one of the most highly aggressive cancer worldwide with an extremely poor prognosis. Evidence has revealed that microRNA-587 (miR-587) is abnormally expressed in a series of cancers. However, its expressions and functions in HCC have not been clearly acknowledged.

Methods

We detected the expression level of miR-587 both in the Gene Expression Omnibus (GEO) database and 86 paired clinical HCC tissues together with paired adjacent normal tissues by quantitative real-time PCR (qRT-PCR). Afterwards, the transfected HCC cell line SMMC-7721 cells were collected for the cell proliferation assay, cell-cycle arrest, cell migration, and invasion assays to explore the roles of miR-587 in regulating cellular function. In addition, bioinformatics analysis, combined with qRT-PCR and dual-luciferase reporter assays, were performed to confirm whether ribosomal protein SA (RPSA) mRNA was the direct target gene of miR-587. Moreover, the Cancer Genome Atlas (TCGA) and GEO databases as well as 86 paired clinical HCC tissues were used to verify the negative regulation between miR-587 and RPSA.

Results

In the present study, both the GEO database (GSE36915 and GSE74618) analysis and qRT-PCR analysis of 86 paired clinical tissues showed that miR-587 was significantly downregulated in HCC tissues. The overexpression of miR-587 inhibited proliferation, cell cycle, migration, and invasion in SMMC-7721 cells. In addition, miR-587 directly interacted with the 3′-untranslated region (UTR) of RPSA. Moreover, miR-587 overexpression directly suppressed RPSA expression, and the two genes were inversely expressed in HCC based on the analyses in TCGA and GEO (GSE36376) databases and qPCR analysis of 86 paired clinical tissues.

Conclusion

Our results demonstrate that miR-587 is downexpressed in HCC and regulates the cellular function by targeting RPSA.

The role of long non-coding RNA MIAT in cancers

Long non-coding RNAs (lncRNAs), a kind of non-coding single-strand RNAs, play an important role as carcinogenic genes or tumor suppressors in the development of human cancer. Myocardial infarction-associated transcript (MIAT) was first identified as a lncRNA in 2006 and originally isolated as a candidate gene for myocardial infarction. Later, it was reported that MIAT exhibits regulatory effects on the human cell cycle. Since its discovery, MIAT has also been identified as a carcinogenic regulator in many malignant tumors. High expression of MIAT is related to the clinicopathological characteristics of cancer patients. It can also regulate cell proliferation, invasion, metastasis, and anti-apoptosis through a variety of mechanisms. Therefore, MIAT is considered a potential biomarker and therapeutic target in cancer. In this review, we summarize the biological function, mechanism, and potential clinical significance of MIAT during tumorigenesis.

Long non-coding RNA MIAT promotes the growth of melanoma via targeting miR-150

Melanoma is a common skin cancer and it can lead to high mortality probably by early invasion and metastasis. LncRNA MIAT is involved in tumor proliferation, invasion and epithelial-to-mesenchymal transition (EMT). However, the roles of MIAT in melanoma still require further investigation. Thus, the aim of the study is to investigate the roles of MIAT in melanoma, especially the effects of MIAT on EMT of melanoma cancer cells. The results showed that the expression of MIAT was significantly upregulated in melanoma tissue and cells compared with the normal skin and normal melanocytes; moreover, miR-150 was confirmed as a target of MIAT. Furthermore, knockdown of MIAT inhibited cell proliferation and invasion in melanoma cancer cells and transfection of miR-150 inhibitors partial abrogated the anti-tumor effects of MIAT siRNA. In addition, MIAT siRNA also inhibited the EMT of melanoma cells, while miR-150 inhibitors can reverse the effects of MIAT siRNA. Finally, knockdown of MIAT also inhibited the carcinogenic effects of melanoma in vivo by targeting miR-150. In conclusion, we reported that MIAT promotes the proliferation, invasion and EMT of melanoma cells via targeting miR-150, which suggested that MIAT might be a therapeutic target for the treatment of melanoma.

lncRNA MIAT Regulates Cell Growth, Migration, and Invasion Through Sponging miR-150-5p in Ovarian Cancer

Background: MIAT (myocardial infarction-associated transcript) regulates cell proliferation, apoptosis, and metastasis in several cancers. In this study, the authors aimed to explore the role of MIAT in ovarian cancer. Materials and Methods: The expression of MIAT in ovarian cancer subtypes, normal human ovarian surface epithelial and ovarian cancer cell lines was measured by qualitative real-time polymerase chain reaction (qRT-PCR). OVCAR3 and SKOV3 cells were transfected with MIAT overexpression plasmid or siMIAT. The cell growth ability was then evaluated by CCK-8 and colony formation assays. The cell migration and invasion rate were separately measured by wound-healing and transwell assays. The levels of epithelial-mesenchymal transition (EMT)-associated markers were evaluated by Western blotting. MIAT sponging miR-150-5p was predicted by starBase and confirmed by dual-luciferase reporter assays. The expression of miR-150-5p in OVCAR3 and SKOV3 cells with MIAT overexpression or knockdown, and in ovarian cancer subtypes was also measured by qRT-PCR. Further analyses confirmed the role of MIAT sponging miR-150-5p in ovarian cancer cells. Results: MIAT was highly expressed in mesenchymal subtype ovarian cancer tissues and ovarian cancer cells. In OVCAR3 and SKOV3 cells, overexpression of MIAT promoted, and knockdown of MIAT suppressed the cell growth, migration, invasion, and EMT. miR-150-5p was sponged and regulated by MIAT. miR-150-5p was downregulated in mesenchymal subtype ovarian cancer. Suppression of cell migration, invasion, and EMT caused by miR-150-5p overexpression was rescued by MIAT overexpression. Conclusions: MIAT acts as an oncogene in ovarian cancer cells through sponging miR-150-5p. MIAT or miR-150-5p expression might be a potential prognostic biomarker for ovarian cancer patients. MIAT and miR-150-5p are potential therapeutic targets in treatment of ovarian cancer.

lncRNA MIAT promotes cell invasion and migration in esophageal cancer

Long non-coding RNAs (lncRNAs) serve crucial roles in carcinogenesis. Myocardial infarction-associated transcript (MIAT), originally isolated as a candidate gene for myocardial infarction, has been revealed to serve as an oncogene in chronic lymphocytic leukaemias and neuroendocrine prostate cancer. However, little is known about its expression pattern, biological function and underlying mechanism in esophageal cancer. Cell lines of esophageal cancer were used in the current study. The results of the present study revealed that MIAT knockdown decreased cell viability, migration, invasion and cell cycle arrest in the G1 phase. Mechanistic assessment revealed that MIAT interacts with histone methyltransferase mixed-lineage leukemia (MLL). The relative proteins expressions were measured by western blotting assay. MIAT knockdown suppressed cell invasion and migration by regulation MMP-2/9 protein expressions. The results of the current study indicated that MIAT expression was associated with esophageal cancer and may serve as a critical target in the progression and metastasis in esophageal cancer.

Long non-coding RNA BRM promotes proliferation and invasion of papillary thyroid carcinoma by regulating the microRNA-331-3p/SLC25A1 axis

Long non-coding RNA BRM (lncBRM) was first identified in liver cancer stem cells and was reported to promote multiple cancer types. However, the function of lncBRM in papillary thyroid carcinoma (PTC) remains unclear. The primary focus of the present study was to determine the biological role of lncBRM in PTC. Reverse transcription-quantitative PCR assays revealed that lncBRM was upregulated in PTC tissues and cells. Cell Counting Kit-8, Transwell invasion and colony-formation assays were performed to assess cell proliferation, invasion and migration, respectively. Furthermore, high expression of lncBRM was associated with poor overall survival time in patients with PTC. lncBRM knockout significantly suppressed cell proliferation, migration and invasion. lncBRM was predicted to bind to microRNA (miR)-331-3p and targets SLC25A1. Overexpression of miR-331-3p or inhibition of SLC25A1 resulted in significantly suppressed proliferation, migration and invasion of PTC cells. Rescue assays demonstrated that inhibition of miR-331-3p significantly abrogated the effects of lncBRM knockout on PTC cell proliferation, migration and invasion. In conclusion, the present study suggests that lncBRM promotes PTC by regulating miR-331-3p and targeting SLC25A1.

MiRNAs as Novel Adipokines: Obesity-Related Circulating MiRNAs Influence Chemosensitivity in Cancer Patients

Adipose tissue is an endocrine organ, capable of regulating distant physiological processes in other tissues via the release of adipokines into the bloodstream. Recently, circulating adipose-derived microRNAs (miRNAs) have been proposed as a novel class of adipokine, due to their capacity to regulate gene expression in tissues other than fat. Circulating levels of adipokines are known to be altered in obese individuals compared with typical weight individuals and are linked to poorer health outcomes. For example, obese individuals are known to be more prone to the development of some cancers, and less likely to achieve event-free survival following chemotherapy. The purpose of this review was twofold; first to identify circulating miRNAs which are reproducibly altered in obesity, and secondly to identify mechanisms by which these obesity-linked miRNAs might influence the sensitivity of tumors to treatment. We identified 8 candidate circulating miRNAs with altered levels in obese individuals (6 increased, 2 decreased). A second literature review was then performed to investigate if these candidates might have a role in mediating resistance to cancer treatment. All of the circulating miRNAs identified were capable of mediating responses to cancer treatment at the cellular level, and so this review provides novel insights which can be used by future studies which aim to improve obese patient outcomes.

The long noncoding RNA myocardial infarction-associated transcript modulates the epithelial-mesenchymal transition in renal interstitial fibrosis

AIMS

Renal interstitial fibrosis (RIF) is marked by the epithelial-mesenchymal transition (EMT) and excessive extracellular matrix deposition. The long noncoding RNA myocardial infarction-associated transcript (MIAT) facilitates RIF; however, the molecular mechanism of MIAT in RIF remains unclear. Here, we explored the possible underlying mechanisms through which MIAT modulates RIF.

MATERIALS AND METHODS

MIAT expression in human renal fibrotic tissues and unilateral ureteral obstruction (UUO) model mice was detected by qPCR. Transforming growth factor β1 (TGF-β1) was introduced to stimulate the EMT in human renal proximal tubular epithelial (HK-2) cells. CCK8, EdU, transwell and wound healing assays were employed to measure cell viability, proliferation, and migration respectively. RNA immunoprecipitation (RIP) assays and dual luciferase reporter assays were applied to determine the relationships among MIAT, miR-145, and EIF5A2.

KEY FINDINGS

MIAT was upregulated in human renal fibrotic tissues and UUO model mice compared with normal tissue adjacent to renal tumors and sham operation mice, respectively. MIAT knockdown reduced cell viability, proliferation, migration, and the EMT in HK-2 cells. Additionally, MIAT served as an endogenous sponge for miR-145 in the TGF-β1-induced-EMT in HK-2 cells, as demonstrated by dual luciferase reporter assays and RIP assays. EIF5A2 was confirmed as a target of miR-145, and MIAT knockdown suppressed EIF5A2 expression by sponging miR-145. Downregulation of EIF5A2 partly reversed induction of the EMT by miR-145 inhibitor transfection.

SIGNIFICANCE

MIAT promoted cell viability, proliferation, migration, and the EMT via regulation of the miR-145/EIF5A2 axis. These data established a potential therapy for RIF.

Long noncoding RNA MIAT promotes the progression of acute myeloid leukemia by negatively regulating miR-495

Acute myeloid leukemia (AML) is a malignant myeloid hematopoietic stem and progenitor cell disease. Studies have shown that the long noncoding RNA (lncRNA) myocardial infarction associated transcript (MIAT) is abundantly expressed in multiple human solid tumors. However, the expression and role of MIAT in AML has not been explored previously. In this study, we find that MIAT is overexpressed in AML patient specimens and AML cell lines. Importantly, upregulation of MIAT is closely related with poor clinical outcome. Further investigations reveal that knockdown of MIAT inhibits the colony formation and proliferation, meanwhile, accelerates the apoptosis of AML cells in vitro. Consistently, MIAT knockdown slows AML progression in immunodeficient mice. Mechanistically, we confirm that MIAT can function as a sponge to inhibit microRNA-495 (miR-495), a tumor suppressor, in AML cells. Collectively, our results demonstrate that MIAT is involved in promoting the progression of AML, at least partly, through negative regulation of miR-495, and therefore provide a promising target for treatment of AML.

Long non-coding RNA LINC00461/miR-149-5p/LRIG2 axis regulates hepatocellular carcinoma progression

Long noncoding RNAs (lncRNAs) have been acknowledged as vital regulators in tumorigenesis of human cancers, including hepatocellular carcinoma (HCC). LINC00461 has been found to promote progression of glioma and breast cancer. Nevertheless, the function of LINC00461 in HCC is still unknown. Here, we found that LINC00461 was upregulated in HCC tissues and positively correlated with advanced stage and metastasis. Furthermore, LINC00461 overexpression in HCC patients predicts unfavorable prognosis. Loss-of-function assays showed that LINC00461 silencing suppressed the proliferation, migration and invasion of HCC cells in vitro, and impeded tumor growth in vivo. Mechanistically, LINC00461 inversely regulates miR-149-5p abundance in HCC. Further investigation indicated that LINC00461 was a competing endogenous RNA (ceRNA) by directly sponging miR-149-5p in HCC cells. Moreover, LRIG2 was identified as the downstream target of miR-149-5p and its expression was regulated by LINC00461/miR-149-5p axis. Restoration of LRIG2 reversed LINC00461 knockdown attenuated HCC cell proliferation, migration and invasion. In summary, our findings revealed that LINC00461 is an oncogene in HCC through regulating miR-149-5p/LRIG2 pathway.