Long Noncoding RNA-LET Suppresses Tumor Growth and EMT in Lung Adenocarcinoma

Identification and analysis of hub genes of hypoxia-immunity in type 2 diabetes mellitus

The chronic metabolic disease named type 2 diabetes (T2D) accounts for over 90% of diabetes mellitus. An increasing number of evidences have revealed that hypoxia has a significantly suppressive effect on cell-mediated immunity, as well as the utilization of glucose in diabetics. Therefore, we aimed to screen and identify hypoxia-immune-related hub genes in T2D through bioinformatic analysis. The Gene Expression Omnibus (GEO) database was used to get T2D gene expression profile data in the peripheral blood samples (GSE184050), and hypoxia-related genes were acquired from Molecular Signatures Database (MSigDB). Differentially expressed mRNAs (DEGs) and lncRNAs (DELs) between T2D and normal samples were identified by DeSeq2 package. The clusterProfiler package was used to perform enrichment analyses for the overlapped genes of DEGs and hypoxia-related genes. Further, Hypoxia-related hub genes were discovered using two machine learning algorithms. Next, the compositional patterns of immune and stromal cells in T2D and healthy groups were estimated by using xCell algorithm. Moreover, we used the weighted correlation network analysis (WGCNA) to examine the connection between genes and immune cells to screen immune-related genes. Gene Set Enrichment Analysis (GSEA) was used to investigate the functions of the hypoxia-immune-related hub genes. Finally, two peripheral blood cohorts of T2D (GSE184050 and GSE95849) as well as the quantitative real-time PCR (qRT-PCR) experiments for clicinal peripheral blood samples with T2D were used for verification analyses of hub genes. And meanwhile, a lncRNA-TF-mRNA network was constructed. Following the differentially expressed analysis, 38 out of 3822 DEGs were screened as hypoxia-related DEGs, and 493 DELs were found. These hypoxia-related DEGs were mainly enriched in the GO terms of pyruvate metabolic process, cytoplasmic vesicle lumen and monosaccharide binding, and the KEGG pathways of glycolysis/gluconeogenesis, pentose phosphate pathway and biosynthesis of nucleotide sugars. Moreover, 7 out of hypoxia-related DEGs were identified as hub genes. There were six differentially expressed immune cell types between T2D and healthy samples, which were further used as the clinical traits for WGCNA to identify AMPD3 and IER3 as the hypoxia-immune-related hub genes. The results of the KEGG pathways of genes in high-expression groups of AMPD3 and IER3 were mainly concentrated in glycosaminoglycan degradation and vasopressin-regulated water reabsorption, while the low-expression groups of AMPD3 and IER3 were mainly associated with RNA degradation and nucleotide excision repair. Finally, when compared to normal samples, both the AMPD3 and IER3 were highly expressed in the T2D groups in the GSE184050 and GSE95849 datasets. The result of lncRNA-TF-mRNA regulatory network showed that lncRNAs such as BACH1-IT1 and SNHG15 might induce the expression of the corresponding TFs such as TFAM and THAP12 and upregulate the expression of AMPD3. This study identified AMPD3 and IER3 as hypoxia-immune-related hub genes and potential regulatory mechanism for T2D, which provided a new perspective for elucidating the upstream molecular regulatory mechanism of diabetes mellitus.

Decoding LncRNAs

Non-coding RNAs (ncRNAs) have been considered as unimportant additions to the transcriptome. Yet, in light of numerous studies, it has become clear that ncRNAs play important roles in development, health and disease. Long-ignored, long non-coding RNAs (lncRNAs), ncRNAs made of more than 200 nucleotides have gained attention due to their involvement as drivers or suppressors of a myriad of tumours. The detailed understanding of some of their functions, structures and interactomes has been the result of interdisciplinary efforts, as in many cases, new methods need to be created or adapted to characterise these molecules. Unlike most reviews on lncRNAs, we summarize the achievements on lncRNA studies by taking into consideration the approaches for identification of lncRNA functions, interactomes, and structural arrangements. We also provide information about the recent data on the involvement of lncRNAs in diseases and present applications of these molecules, especially in medicine.

Comprehensive analysis of long noncoding RNA and mRNA in five colorectal cancer tissues and five normal tissues

The present study investigated the role of abnormally expressed mRNA and long noncoding RNA (lncRNA) in the development of colorectal cancer (CRC). We used lncRNA sequencing to analyze the transcriptome (mRNA and lncRNA) of five pairs of CRC tissues and adjacent normal tissues. The total expression of mRNAs and lncRNAs in each sample was determined using the R package and the gene expression was calculated using normalized FPKM. The structural features and expression of all detected lncRNAs were compared with those of mRNAs. Differentially expressed mRNAs were selected to perform Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. The functional analysis of differentially expressed lncRNAs was performed by analyzing the GO and KEGG enrichment of predicted cis-regulated target genes. A total of 18.2 × 10⁸ reads were obtained by sequencing, in which the clean reads reached ≥ 94.67%, with a total of 245.2 G bases. The number of mRNAs and lncRNAs differentially expressed in CRC tissues and normal tissues were 113 and 6, respectively. Further predictive analysis of target genes of lncRNAs revealed that six lncRNA genes had potential cis-regulatory effects on 13 differentially expressed mRNA genes and co-expressed with 53 mRNAs. Up-regulated CTD-2256P15.4 and RP11-229P13.23 were the most important lncRNAs in these CRC tissues and involved in cell proliferation and pathway in cancer. In conclusion, our study provides evidence regarding the mRNA and lncRNA transcription in CRC tissues, as well as new insights into the lncRNAs and mRNAs involved in the development of CRC.

Involvement of long non-coding RNAs in the progression of esophageal cancer

Esophageal cancer (EC) is one of the most common malignant tumors of the digestive system with high incidence and mortality rate worldwide. Therefore, exploring the pathogenesis of EC and searching for new targeted therapies are the current research hotspot for EC treatment. Long non‐coding RNAs (lncRNAs) are endogenous RNAs with more than 200 nucleotides, but without protein‐coding function. In recent years, lncRNAs have gradually become the focuses in the field of non‐coding RNA. Some lncRNAs have been proved to be closely related to the pathogenesis of EC. Many lncRNAs are abnormally expressed in EC and participate in many biological processes including cell proliferation, apoptosis, and metastasis by inhibiting or promoting target gene expression. LncRNAs can also regulate the progression of EC through epithelial‐mesenchymal transformation (EMT), which is closely related to the occurrence, development, and prognosis of EC. In this article, we review and discuss the involvement of lncRNAs in the progression of EC.

Roles of Wnt/β-Catenin Signaling Pathway Regulatory Long Non-Coding RNAs in the Pathogenesis of Non-Small Cell Lung Cancer

Lung cancer is one of the leading causes of cancer-related mortality worldwide. Non-small cell lung cancer (NSCLC) is the most common pathological type of lung cancer. Long non-coding RNAs (lncRNAs) are promising novel diagnostic and prognostic biomarkers, as well as potential therapeutic targets for lung cancer. Long non-coding RNAs (lncRNAs) have been demonstrated to modulate tumor cells proliferation, cell cycle progression, invasion, and metastasis by regulating gene expression at transcriptional, post-transcriptional, and epigenetic levels. The oncogenic aberrant Wnt/β-catenin signaling is prominent in lung cancer, playing a vital role in tumorigenesis, prognosis, and resistance to therapy. Interestingly, compelling studies have demonstrated that lncRNAs exert either oncogenic or tumor suppressor roles by regulating Wnt/β-catenin signaling. In this review, we aim to present the current accumulated knowledge regarding the roles of Wnt/β-catenin signaling-regulated lncRNAs in the pathogenesis of non-small cell lung cancer (NSCLC). Better understanding of the effects of lncRNAs on Wnt/β-catenin signaling might contribute to the improved understanding of the molecular tumor pathogenesis and to the uncovering of novel therapeutic targets in NSCLC.

LncRNA GMDS-AS1 inhibits lung adenocarcinoma development by regulating miR-96-5p/CYLD signaling

According to the global cancer statistic, lung cancer is one of the most dangerous tumors, which poses a serious threat to human health. Exploration the mechanism of lung cancer and new targeted therapeutic measures is always the hot topic. Long noncoding RNA (lncRNA) is an important factor affecting the development of tumors. However, the research on the mechanism of lncRNA in the progress of lung cancer needs to be further expanded. In this study, we found that the expression of lncRNA GMDS-AS1 was significantly reduced in lung adenocarcinoma (LUAD) tissues and cells. Upregulated GMDS-AS1 can significantly inhibit the proliferation of LUAD cells and promote cell apoptosis in vitro and in vivo. The results indicate that GMDS-AS1 acts as a tumor suppressor gene to affect the development of LUAD. Further studies revealed that GMDS-AS1 is a target gene of miR-96-5p, and GMDS-AS1 regulates proliferation and apoptosis of LUAD cells in association with miR-96-5p. In addition, we also confirmed that CYLD lysine 63 deubiquitinase (CYLD) is also a target gene of miR-96-5p. Through various validations, we confirmed that GMDS-AS1 can act as a ceRNA to upregulate the expression of CYLD by sponging miR-96-5p. Moreover, the intervention of GMDS-AS1/miR-96-5p/CYLD network can regulate the proliferation and apoptosis of LUAD cells. In this study, we revealed that the GMDS-AS1/miR-96-5p/CYLD network based on ceRNA mechanism plays an important role in the development of LUAD and provides a new direction and theoretical basis for targeted therapy of LUAD.

LncRNA-LET inhibits cell growth of clear cell renal cell carcinoma by regulating miR-373-3p

Background

Clear cell renal cell carcinoma (ccRCC) is the most common renal cell carcinoma subtype with a poor prognosis. LncRNA-LET is a long non-coding RNA (lncRNA) that is down-regulated in ccRCC tissues. However, its role in ccRCC development and progress is unclear.

Methods

LncRNA-LET expression was detected in ccRCC tissues and ccRCC cells using quantitative real-time PCR. The overexpression and knockdown experiments were performed in ccRCC cells and xenograft mouse model to evaluate role of lncRNA-LET. Cell cycle, apoptosis and JC-1 assays were conducted via flow cytometer. The protein levels were measured through western blot analysis and the interaction between lncRNA-LET and miR-373-3p was identified via luciferase reporter assay.

Results

LncRNA-LET expression was lower in ccRCC tissues than that in the matched adjacent non-tumor tissues (n = 16). In vitro, lncRNA-LET overexpression induced cell cycle arrest, promoted apoptosis and impaired mitochondrial membrane potential, whereas its knockdown exerted opposite effects. Moreover, we noted that lncRNA-LET may act as a target for oncomiR miR-373-3p. In contrast to lncRNA-LET, miR-373-3p expression was higher in ccRCC tissues. The binding between lncRNA-LET and miR-373-3p was validated. Two downstream targets of miR-373-3p, Dickkopf-1 (DKK1) and tissue inhibitor of metalloproteinase-2 (TIMP2), were positively regulated by lncRNA-LET in ccRCC cells. MiR-373-3p mimics reduced lncRNA-LET-induced up-regulation of DKK1 and TIMP2 levels, and attenuated lncRNA-LET-mediated anti-tumor effects in ccRCC cells. In vivo, lncRNA-LET suppressed the growth of ccRCC xenograft tumors.

Conclusion

These findings indicate that lncRNA-LET plays a tumor suppressive role in ccRCC by regulating miR-373-3p.

Long non-coding RNAs in non-small cell lung cancer: functions and distinctions from other malignancies

Lung cancer leads to the most cancer-related death in the world. It was shown from the increasing evidences that long non-coding RNAs (lncRNAs) are emerging as molecules for diagnosis, prognosis and even therapy of lung cancer and other malignancies. The biological functions or involved signaling pathways of lncRNAs are always found to be inconsistent among different types of malignancies. However, no available literature has systemically summarized differences in the functions and underlying molecular mechanisms of lncRNAs between lung cancer and other cancers. In this review, the biological functions and molecular mechanisms of lncRNAs in lung cancer were introduced. Furthermore, their functional differences between lung cancer and other malignancies were discussed. Finally, their potential clinical applications in future lung cancer therapy were focused on.

Negative regulators of Wnt signaling in non-small cell lung cancer: Theoretical basis and therapeutic potency

Significant advances in the treatment of non-small cell lung cancer (NSCLC) have been made over the past decade, and they predominantly involve molecular targets such as epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) rearrangements. However, despite the initial good response, drug resistance eventually develops. The Wnt signaling pathway has recently been considered important in embryonic development and tumorigenesis in many cancers, particularly NSCLC. Moreover, the aberrant Wnt pathway plays a significant role in NSCLC and is associated with cancer cell proliferation, metastasis, invasion and drug resistance, and the suppression of canonical or noncanonical Wnt signaling through various biological or pharmacological negative regulators has been proven to produce specific anticancer effects. Thus, blocking the Wnt pathway via its negative regulators may overcome the resistance of current treatment methods and lead to new treatment strategies for NSCLC. Therefore, in this review, we summarize recent studies on the role of negative regulators in Wnt signaling in NSCLC and the therapeutic potency of these molecules as agents and targets for NSCLC treatments.

Phytochemicals as Modulators of Long Non-Coding RNAs and Inhibitors of Cancer-Related Carbonic Anhydrases

Long non-coding RNAs (lncRNAs) are classified as a group of transcripts which regulate various biological processes, such as RNA processing, epigenetic control, and signaling pathways. According to recent studies, lncRNAs are dysregulated in cancer and play an important role in cancer incidence and spreading. There is also an association between lncRNAs and the overexpression of some tumor-associated proteins, including carbonic anhydrases II, IX, and XII (CA II, CA IX, and CA XII). Therefore, not only CA inhibition, but also lncRNA modulation, could represent an attractive strategy for cancer prevention and therapy. Experimental studies have suggested that herbal compounds regulate the expression of many lncRNAs involved in cancer, such as HOTAIR (HOX transcript antisense RNA), H19, MALAT1 (metastasis-associated lung adenocarcinoma transcript 1), PCGEM1 (Prostate cancer gene expression marker 1), PVT1, etc. These plant-derived drugs or phytochemicals include resveratrol, curcumin, genistein, quercetin, epigallocatechin-3-galate, camptothcin, and 3,3′-diindolylmethane. More comprehensive information about lncRNA modulation via phytochemicals would be helpful for the administration of new herbal derivatives in cancer therapy. In this review, we describe the state-of-the-art and potential of phytochemicals as modulators of lncRNAs in different types of cancers.

Gossypol Promotes Wnt/β-Catenin Signaling through WIF1 in Ovariectomy-Induced Osteoporosis

Osteoporosis is one of the most frequent diseases related with age. Previously, we have reported a novel potential drug, gossypol, for the treatment of osteoporosis through its regulation of Wnt/β-catenin signaling. This study aims to identify the detailed mechanism of gossypol in human osteoporosis. Mice injected with gossypol were subjected for RNA-seq analysis and the transcription level of WIF1 was shown to be decreased dramatically in gossypol-treated mice, which was further confirmed by qRT-PCR and western blot analysis. Luciferase reporter assay showed gossypol inhibited the activity of WIF1 and the methylation of WIF1 was significantly upregulated, evidenced by ChIP assay. Cell viability assays demonstrated that gossypol promoted cell proliferation while cotreatment with WIF1 expressing plasmid reversed the effect in a dose- and time-dependent manner. Similarly, cell apoptotic assays and TUNEL assays showed gossypol suppressed cell apoptosis, which was revised by WIF1 overexpression. The mouse model suggested gossypol injection ameliorated osteoporosis, while coinjection of AAV5-WIF1 eliminated the protection effects of gossypol, as evidenced by H&E staining, serum osteocalcin level, serum OPG level, serum RANKL level, bone density, ultimate strength, and postyield displacement. This study is a supplement to the former publication, which reinforced the protection effect of gossypol in human osteoporosis.

Long non-coding RNAs as pan-cancer master gene regulators of associated protein-coding genes: a systems biology approach

Despite years of research, we are still unraveling crucial stages of gene expression regulation in cancer. On the basis of major biological hallmarks, we hypothesized that there must be a uniform gene expression pattern and regulation across cancer types. Among non-coding genes, long non-coding RNAs (lncRNAs) are emerging as key gene regulators playing powerful roles in cancer. Using TCGA RNAseq data, we analyzed coding (mRNA) and non-coding (lncRNA) gene expression across 15 and 9 common cancer types, respectively. 70 significantly differentially expressed genes common to all 15 cancer types were enlisted. Correlating with protein expression levels from Human Protein Atlas, we observed 34 positively correlated gene sets which are enriched in gene expression, transcription from RNA Pol-II, regulation of transcription and mitotic cell cycle biological processes. Further, 24 lncRNAs were among common significantly differentially expressed non-coding genes. Using guilt-by-association method, we predicted lncRNAs to be involved in same biological processes. Combining RNA-RNA interaction prediction and transcription regulatory networks, we identified E2F1, FOXM1 and PVT1 regulatory path as recurring pan-cancer regulatory entity. PVT1 is predicted to interact with SYNE1 at 3′-UTR; DNAJC9, RNPS1 at 5′-UTR and ATXN2L, ALAD, FOXM1 and IRAK1 at CDS sites. The key findings are that through E2F1, FOXM1 and PVT1 regulatory axis and possible interactions with different coding genes, PVT1 may be playing a prominent role in pan-cancer development and progression.

Long noncoding RNAs in cancer cells

Long noncoding RNA (lncRNA) has recently been investigated as key modulators that regulate many biological processes in human cancers via diverse mechanisms. LncRNAs can interact with macromolecules such as DNA, RNA, or protein to exert cellular effects and to act as either tumor promoters or tumor suppressors in various malignancies. Moreover, the aberrant expression of lncRNAs may be detected in multiple cancer phenotypes by employing the rapidly developing modern gene chip technology and bioinformatics analysis. Herein, we highlight the mechanisms of action of lncRNAs, their functional cellular roles and their involvement in cancer progression. Finally, we provide an overview of recent progress in the lncRNA field and future potential for lncRNAs as cancer diagnostic markers and therapeutics.

Long non‑coding RNA MLK7‑AS1 promotes proliferation in human colorectal cancer via downregulation of p21 expression

Current studies have highlighted long non‑coding RNAs (lncRNAs) as critical regulators in various cancers, including colorectal cancer (CRC). By utilizing publicly available data from The Cancer Genome Atlas dataset, MLK7 antisense RNA 1 (MLK7‑AS1) was identified as a novel lncRNA that correlated with CRC progression. The results of reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) revealed a significant upregulation of MLK7‑AS1 in both CRC tissue samples and cell lines. In addition, a positive correlation was observed between increased MLK7‑AS1 expression and several clinicopathological factors in patients with CRC. Importantly, MLK7‑AS1 knockdown suppressed CRC cell proliferation and promoted G1/G0 phase arrest and apoptosis in vitro, whereas MLK7‑AS1 overexpression exhibited opposite effects. Consistently, decreased MLK7‑AS1 expression inhibited tumor growth in vivo. Furthermore, RT‑qPCR and western blot assays revealed that p21 may be a potential downstream target of MLK7‑AS1. To the best of the authors' knowledge, this is the first study to report that MLK7‑AS1 has potential as a biomarker and may promote proliferation in CRC partially through downregulating p21 expression.

LncRNA HOTAIR/miR-613/c-met axis modulated epithelial-mesenchymal transition of retinoblastoma cells

Since lncRNAs could modulate neoplastic development by modulating downstream miRNAs and genes, this study was carried out to figure out the synthetic contribution of HOTAIR, miR-613 and c-met to viability, apoptosis and proliferation of retinoblastoma cells. Totally 276 retinoblastoma tissues and tumour-adjacent tissues were collected, and human retinoblastoma cell lines (ie, Y79, HXO-Rb44, SO-Rb50 and WERI-RB1) were also gathered. Moreover, transfections of pcDNA3.1-HOTAIR, si-HOTAIR, miR-613 mimic, miR-613 inhibitor, pcDNA3.1/c-met were performed to evaluate the influence of HOTAIR, miR-613 and c-met on viability, apoptosis and epithelial-mesenchymal transition (EMT) of retinoblastoma cells. Dual-luciferase reporter gene assay was also arranged to confirm the targeted relationship between HOTAIR and miR-613, as well as between miR-613 and c-met. Consequently, up-regulated HOTAIR and down-regulated miR-613 expressions displayed associations with poor survival status of retinoblastoma patients (P < 0.05). Besides, inhibited HOTAIR and promoted miR-613 elevated E-cadherin expression, yet decreased Snail and Vimentin expressions (P < 0.05). Simultaneously, cell proliferation and cell viability were also less-motivated (P < 0.05). Nonetheless, c-met prohibited the functioning of miR-613, resulting in promoted cell proliferation and viability, along with inhibited cell apoptosis (P < 0.05). Finally, HOTAIR was verified to directly target miR-613, and c-met was the direct target gene of miR-613 (P < 0.05). In conclusion, the role of lncRNA HOTAIR/miR-613/c-met signalling axis in modulating retinoblastoma cells' viability, apoptosis and expressions of EMT-specific proteins might provide evidences for developing appropriate diagnostic and treatment strategies for retinoblastoma.

Interaction of long-chain non-coding RNAs and important signaling pathways on human cancers (Review)

Long non-coding RNAs (lncRNAs) usually refer to non-coding RNA transcripts >200 nucleotides in length. In terms of the full genomic transcript, the proportion of lncRNAs far exceeds that of coding RNA. Initially, lncRNAs were considered to be the transcriptional noise of genes, but it has since been demonstrated that lncRNAs serve an important role in the regulation of cellular activities through interaction with DNA, RNA and protein. Numerous studies have demonstrated that various intricate signaling pathways are closely related to lncRNAs. Here, we focus on a large number of studies regarding the interaction of lncRNAs with important signaling pathways. It is comprehensively illustrated that lncRNAs regulate key metabolic components and regulatory factors of signaling pathways to affect the biological activities of tumor cells. Evidence suggests that the abnormal expression or mutation of lncRNAs in human tumor cells, and their interaction with signaling pathways, may provide a basis and potential target for the diagnosis and treatment of human cancers.

Long noncoding RNA MLK7-AS1 promotes ovarian cancer cells progression by modulating miR-375/YAP1 axis

Background

Long noncoding RNAs (LncRNAs) have been reported to be abnormally expressed in human ovarian cancer and associated with the proliferation and metastasis of cancer cells. The objective of this study was to investigate the role and the underlying mechanisms of LncRNA MAP3K20 antisense RNA 1 (MLK7-AS1) in ovarian cancer.

Methods

The expression level of MLK7-AS1 was investigated in human ovarian cancer tissues and cell lines. The effects of MLK7-AS1 knockdown on ovarian cancer cell proliferation, migration, invasion and apoptosis were evaluated in vitro using MTT, colony formation assays, wound healing assays, transwell assays and flow cytometry. Furthermore, the in vivo effects were determined using the immunodeficient NSG female mice. Luciferase reporter assays were employed to identify interactions among MLK7-AS1 and its target genes.

Results

In the current study, MLK7-AS1 was specifically upregulated in ovarian cancer tissues and cell lines. Knockdown of MLK7-AS1 inhibited the ability of cell migration, invasion, proliferation, colony formation and wound healing, whereas promoted cell apoptosis in vitro. By using online tools and mechanistic analysis, we demonstrated that MLK7-AS1 could directly bind to miR-375 and downregulate its expression. Besides, MLK7-AS1 reversed the inhibitory effect of miR-375 on the growth of ovarian cancer cells, which might be involved in the upregulation of Yes-associated protein 1 (YAP1) expression. Moreover, knockdown MLK7-AS1 expression inhibited primary tumor growth in ovary and metastatic tumors in multiple peritoneal organs including liver and spleen in vivo, which were partly abolished by miR-375 inhibition. Mechanically, we found that MLK7-AS1 modulated the epithelial-mesenchymal transition (EMT) process by interacting with miR-375/YAP1 both in vivo and vitro, which promoted the expression of Slug.

Conclusions

Taken together, our study showed for the first time that MLK7-AS1 interacted with miR-375 to promote proliferation, metastasis, and EMT process in ovarian cancer cells through upregulating YAP1.

lncRNA involvement in hepatocellular carcinoma metastasis and prognosis

Eukaryotic lncRNAs are RNA molecules defined to be greater than 200 bp in length that are not translated to a protein and operate through several mechanisms, including participating in chromatin remodeling and methylation, influencing the integrity and stability of proteins and complexes, or acting as a sponge for miRNA inhibition. A number of recent studies have concentrated on the relationship between long non-coding RNAs (lncRNAs) and cancer. Hepatocellular carcinoma (HCC) is the most prevalent histological type of liver tumors, accounting for about 80 % of the cases worldwide. Lack of proper molecular markers for diagnosis of HCC and treatment evaluation is a significant problem. Dysregulated expression of HCC-related lncRNAs such as MEG-3, MALAT1, HULC, HOTAIR, and H19 have been identified and closely related with tumorigenesis, metastasis, prognosis and diagnosis. In this review, we summarized recent highlighted functions and molecular mechanisms of the most extensively studied lncRNAs in the pathophysiology of hepatocellular carcinoma and their potential for serving as probable therapeutic targets.

Long non-coding RNA-ENST00000434223 suppresses tumor progression in gastric cancer cells through the Wnt/β-catenin signaling pathway

BACKGROUND

Gastric cancer (GC) develops from the lining of the stomach. The present study aimed to explore the effects of long non-coding RNA-ENST00000434223 (lncRNA ENST00000434223) on gastric cancer (GC) cells.

METHODS

One hundred and four GC tissues and paracancerous tissues were collected from GC patients, and expression of ENST00000434223, Wnt2b, β-catenin, cyclinD1, E-cadherin, N-cadherin, vimentin, and snail was subsequently assessed. Morphological changes in cells were assessed using an inverted microscope, and expression of Bcl-2, Bax and caspase-3 was examined.

RESULTS

We found that expression of Wnt2b, β-catenin, cyclinD1, N-cadherin, vimentin, and snail was increased in GC tissues, while expression of ENST00000434223 and E-cadherin was decreased. SGC-7901 cells were closely arranged, and expression of Wnt2b, β-catenin, CyclinD1, N-cadherin, Vimentin, snail and Bcl-2 was increased, whereas expression of ENST00000434223, E-cadherin, Bax and caspase-3 was decreased. Furthermore, the rate of apoptosis was decreased and cell proliferation, invasion and migration were increased in response to downregulation of ENST00000434223. By contrast, upregulation of ENST00000434223 exhibited the opposite effects in MKN-45 cells.

CONCLUSION

The results of this study provide a promising experimental basis for the treatment of gastric cancer through interventional targeting of lncRNA ENST00000434223.

Mn12Ac inhibits the migration, invasion and epithelial-mesenchymal transition of lung cancer cells by downregulating the Wnt/β-catenin and PI3K/AKT signaling pathways

Lung cancer is the leading cause of global cancer-associated mortality, therefore it is important to reveal the molecular mechanisms of lung cancer progression and to develop novel therapeutic targets. The results of the present study identified that manganese-12 acetate (Mn12Ac) was able to significantly inhibit the migration and invasion of A549 cells. Western blotting demonstrated that treatment with Mn12Ac was able to upregulate E-cadherin, and downregulate N-cadherin and vimentin. It was also identified by a quantitative polymerase chain reaction analysis that Mn12Ac was able to reduce the mRNA expression levels of EMT-associated transcription factors Snail, Slug, Twist-related protein 1 and zinc finger E-box-binding homeobox 1. It was also demonstrated that Mn12Ac was able to reduce the expression levels of Wnt and β-catenin proteins, and suppress the phosphorylation of phosphoinositide 3-kinase (PI3K) and AKT in A549 cells. Notably, it was revealed that Mn12Ac was able to decrease the mRNA and protein expression levels of programmed death ligand-1. Taken together, the results suggested that Mn12Ac is able to inhibit cell migration, invasion and EMT in lung cancer cells by regulating the Wnt/β-catenin and PI3K/AKT signaling pathways.

Manganese-12 acetate suppresses the migration, invasion, and epithelial-mesenchymal transition by inhibiting Wnt/β-catenin and PI3K/AKT signaling pathways in breast cancer cells

BACKGROUND

Breast cancer is the leading cause of cancer-related death in the world, and it is of great value to reveal the molecular mechanisms of breast cancer progression and develop new therapeutic targets.

METHODS

Transwell assay is used to analyze the migration and invasion of breast cancer cells. Real-time PCR and western blotting assay are applied to detect the expression levels of epithelial-mesenchymal transition markers and the key members of Wnt/β-catenin and PI3K/AKT signaling pathways.

RESULTS

Manganese-12 acetate (Mn12Ac) significantly inhibited the migration and invasion of MCF7 and MDA-MB-231 breast cancer cells. Western blotting assay further showed that Mn12Ac significantly upregulated E-cadherin, and downregulated N-cadherin and vimentin. We further found that Mn12Ac reduced the mRNA expressions of epithelial-mesenchymal transition-associated transcription factors snail, slug, twist1, and ZEB1 using real-time PCR assay. Importantly, we further found that Mn12Ac significantly reduced the Wnt1 and β-catenin protein expressions, and suppressed the phosphorylation of PI3K and AKT in MCF7 and MDA-MB-231 breast cancer cells. Very interestingly, we also showed that Mn12Ac decreased the mRNA and protein expressions of programmed cell death ligand 1.

CONCLUSION

Taken together, our results suggested that Mn12Ac inhibited the migration, invasion, and epithelial-mesenchymal transition by regulating Wnt/β-catenin and PI3K/AKT signaling pathways in breast cancer.

Long noncoding RNA PVT1 promotes EMT via mediating microRNA-186 targeting of Twist1 in prostate cancer

The pathogenesis and the underlying mechanism of endothelial-mesenchymal transition in prostate cancer remain unclear. Plasmacytoma variant translocation 1 (PVT1), a novel long non-coding RNA maps to 8q24.21, and in many tumor studies the up-regulation of PVT1 has already been reported. PVT1 is closely related to tumor cell proliferation, invasion, and metastasis. In this study, we employed a combination of techniques to study the role of PVT1 in prostate cancer, which included bioinformatic analysis, Western blotting and cell migration assays of prostate cancer cell lines. We report that PVT1 promotes prostate cancer invasion and metastasis by modulating EMT. Furthermore, PVT1 can promote EMT by up-regulation of Twist1, a transcription factor associated with EMT. We then confirmed that PVT1 acts as a sponge for miRNA-186-5p and positively regulates Twist1 by a sponge effect. Therefore, this study has revealed a novel MECHANISM for the promotion of EMT in prostate cancer by PVT1. Our findings suggest that the PVT1/miR-186/Twist1 regulatory axis may be a new therapeutic target for prostate cancer.

Downregulation of long non-coding RNA LET predicts poor prognosis and increases Notch signaling in non-small cell lung cancer

Long non-coding RNAs (lncRNAs) have been found to be dysregulated in a variety of tumors. The lncRNA-Low Expression in Tumor (LET) is a recently identified lncRNA, but its expression pattern and biological significance in human non-small cell lung cancer (NSCLC) are still largely unknown. In this study, we found that lncRNA-LET was significantly downregulated in human NSCLC lung tissues and cell lines. Decreased lncRNA-LET expression was strongly associated with advanced tumor stages and poorer overall survival of NSCLC patients. Functionally, overexpression of lncRNA-LET in NSCLC H292 cells significantly suppressed cell proliferation, migration and invasion, and promoted cell cycle arrest and apoptosis, while knockdown of lncRNA-LET in NSCLC H1975 cells showed an opposite effect, pointing to a tumor-suppressive role for lncRNA-LET in NSCLC. Mechanistically, we demonstrated that lncRNA-LET overexpression significantly reduced the expression of Notch1 intracellular Domain (NICD1) in H292 cells while knockdown of lncRNA-LET increased NICD1 expression in H1975 cells. Similarly, NSCLC lung tissues with high levels of lncRNA-LET had lower NICD1 expression. Thus, our results provide a strong rationale for lncRNA-LET to be used as a prognostic indicator and a potent therapeutic target for NSCLC patients, and highlight a novel lncRNA-LET/Notch axis in regulating NSCLC cell fate and tumor progression.

Long non-coding RNA HOXA11-AS promotes the proliferation HCC cells by epigenetically silencing DUSP5

Hepatocellular carcinoma has been identified as the fifth most common cancer in men and the ninth in women worldwide. Despite many efforts have been made in recent years, the overall survival rate of patients with hepatocellular carcinoma still remain unsatisfied. Therefore, exploring the mechanisms underlying the progression of hepatocellular carcinoma is essential for developing novel treatments to improve patient prognosis. HOXA11-AS, transcribed from the opposite strand of the protein-coding gene HOXA11, has been identified to be associated with the malignant characteristics of several cancers. However, the biological role and molecular mechanism of HOXA11-AS in hepatocellular carcinoma still need to be further investigated. In the current study, the expression of HOXA11-AS in the hepatocellular carcinoma cell lines and tissues was measured by quantitative real-time PCR. Loss-of-function and gain-of-function approaches were applied to investigate the proliferative function of HOXA11-AS in hepatocellular carcinoma cells. Results from flow cytometric analysis of apoptosis and cell cycle distribution revealed that HOXA11-AS promoted hepatocellular carcinoma cells proliferation through regulating cell cycle and apoptosis. Gene chip technology and quantitative real-time PCR confirmed that DUSP5 was a downstream target of HOXA11-AS. RNA immune co-precipitation assays, RNA pull-down and Chromatin immunoprecipitation assays confirmed that HOXA11-AS could recruit EZH2 to the promoter region of DUSP5, which therefore suppressed the transcription of DUSP5. Collectively, these findings revealed that HOXA11-AS functions as an oncogene in hepatocellular carcinoma through interacting with polycomb-repressive complex2.

Suppression of long non-coding RNA LET potentiates bone marrow-derived mesenchymal stem cells (BMSCs) proliferation by up-regulating TGF-β1

Long non coding RNAs (lncRNAs) show an encouraging trend in regulating the proliferation of bone marrow-derived mesenchymal stromal cells (BMSCs). The present study investigated the role of lncRNA low expression in tumor (LET) in BMSCs proliferation. Our result showed that LET was down-regulated in rapidly proliferated BMSCs (P < 0.05). Suppression of LET promoted BMSCs proliferation and over-expression of LET inhibited BMSCs proliferation (P < 0.05). LET negatively regulated the expression of transforming growth factor β1 (TGF-β1) in BMSCs (P < 0.05). Knockdown of TGF-β1 reversed the LET suppression-induced BMSCs proliferation (P < 0.05). Moreover, knockdown of TGF-β1 alleviated the LET suppression-induced activation of Wnt/β-catenin pathway in BMSCs. Therefore, we drew the conclusion that LET suppression promoted BMSCs proliferation by up-regulating the expression of TGF-β1 and activating Wnt/β-catenin pathway.

Up-regulated miR-548k promotes esophageal squamous cell carcinoma progression via targeting long noncoding RNA-LET

Dysregulated noncoding RNAs have been observed in diverse cancers. MIR458K is frequently amplified in esophageal squamous cell carcinoma (ESCC). However, the expression, clinical significances, and action mechanisms of miR-548k in ESCC are still unclear. In this study, we found that miR-548k is significantly up-regulated in ESCC tissues and cell lines. Up-regulated miR-548k expression is significantly correlated with advanced invasion depth, lymph node metastasis, advanced TNM stage, and poor overall survival. Gain-of- and loss-of-function assays demonstrated that miR-548k promotes the proliferation and migration of ESCC cells in vitro and tumor growth in vivo. Mechanistically, we found that miR-548k directly targets and represses the expression of long noncoding RNA-LET (lncRNA-LET), and further down-regulates p53 and up-regulates NF90. In addition, we found that lncRNA-LET is down-regulated and inversely correlated with miR-548k in ESCC. Down-regulated lncRNA-LET also indicated poor overall survival of ESCC patients. Functional assays demonstrated that lncRNA-LET inhibits the proliferation and migration of ESCC cells, and the effects of miR-548k on ESCC are dependent on the negative regulation of lncRNA-LET. In summary, our data revealed the critical roles of miR-548k-lncRNA-LET regulation axis in ESCC and suggested that the miR-548k-lncRNA-LET regulation axis may be promising prognostic biomarkers and therapeutic targets for ESCC.

LncRNA DANCR promotes migration and invasion through suppression of lncRNA-LET in gastric cancer cells

Gastric cancer (GC) is one of the most prevalent gastrointestinal malignancies. Long noncoding RNA (lncRNA) DANCR is a newly identified oncogenic lncRNA. However, the functional role and underlying molecular mechanisms of DANCR involved in GC progress remain unclear. In the present study, we investigated the biological function and underlying mechanisms of DANCR in GC cell migration and invasion. The results showed that knockdown of DANCR inhibited migration and invasion of GC cells, whereas overexpression of DANCR showed the opposite effect. Further investigation demonstrated that lncRNA-LET was a bona fide target gene of DANCR. In addition, high DANCR and low lncRNA-LET were significantly correlated with lymph node metastasis and late clinical stage. DANCR associated with EZH2 and HDAC3 to epigenetically silence lncRNA-LET and then regulated GC migration and invasion. Taken together, these findings indicate an important role for DANCR–lncRNA-LET axis in GC cell migration and invasion, and reveal a novel epigenetic mechanism for lncRNA-LET silencing.

Human nonsense-mediated RNA decay regulates EMT by targeting the TGF-ß signaling pathway in lung adenocarcinoma

Nonsense-mediated mRNA decay (NMD) is a highly conserved pathway that selectively degrades aberrant RNA transcripts. In this study, we proved that NMD regulates the epithelial-mesenchymal transition (EMT) of lung adenocarcinoma (ADC). Moreover, we found that NMD core factor UP-frameshift 1 tends to be expressed at lower levels in human ADC tissues than in normal lung tissues, thereby raising the possibility that NMD may be downregulated to permit ADC oncogenesis. Our experiments in human ADC cell lines showed that downregulating NMD can promote EMT. Moreover, EMT can be inhibited by upregulating NMD. We tested the role of TGF-ß signaling and found that NMD influences EMT by targeting the TGF-ß signaling pathway. Our findings reveal that NMD is a potential tumor regulatory mechanism and may be a potential therapeutic target for ADC.

Long Noncoding RNAs as Biomarkers in Cancer

Long noncoding RNAs (lncRNAs) are a relatively well-characterized class of noncoding RNA (ncRNA) molecules, involved in the regulation of various cell processes, including transcription, intracellular trafficking, and chromosome remodeling. Their deregulation has been associated with the development and progression of various cancer types, the fact which makes them suitable as biomarkers for cancer diagnosis and prognosis. In recent years, detection of cancer-associated lncRNAs in body fluids of cancer patients has proven itself as an especially valuable method to effectively diagnose cancer. Cancer diagnosis and prognosis employing circulating lncRNAs are preferential when compared to classical biopsies of tumor tissues, especially due to their noninvasiveness, and have great potential for routine usage in clinical practice. Thus, this review focuses on summarizing the perspectives of lncRNAs as biomarkers in cancer, based on evaluating their expression profiles determined in body fluids of cancer patients.

Long non-coding RNA XIST exerts oncogenic functions in human glioma by targeting miR-137

Long non-coding RNA (lncRNA) X inactivate-specific transcript (XIST) acts as an important regulator in tumor progression. However, its expression and the underlying mechanism in glioma remain unclear. The aim of this study was to explore the potential function of XIST in glioma progression. In the present study, our data showed that the expression of XIST was significantly up-regulated in glioma tissues and enhanced the proliferation of glioma cells. The expression of miR-137 was significantly decreased in glioma tissues. Further correlation analysis demonstrated that there was a negative correlation between XIST expression and miR-137 expression. Bioinformatics prediction and luciferase reporter assays demonstrated that miR-137 could directly bind to XIST and negatively regulated the expression of miR-137. Additionally, our data further showed that XIST could up-regulate the expression of miR-137 targeted gene Rac1 through acting as an endogenous sponge of miR-137. In addition, we found that Rac1 inhibition or miR-137 overexpression could suppress glioma cells proliferation induced by XIST overexpression. Thus, a novel XIST-miR-137-Rac1 pathway regulatory axis in glioma pathogenesis was revealed in the present study. Overall, our study indicated that XIST could be a potential therapeutic target in the treatment of glioma.

Long Non-Coding RNA Reprogramming (ROR) Promotes Cell Proliferation in Colorectal Cancer via Affecting P53

BACKGROUND Colorectal cancer (CRC) remains one of the most common lethal malignant tumors worldwide. The correlation between lncRNAs expression and CRC development has not been well identified in the recent literature. This study focused on the role of lncRNA-ROR on CRC progression and development. MATERIAL AND METHODS Quantitative real-time PCR (qRT-PCR) assay was conducted to identify the expression level of lncRNA-ROR. Cell proliferation and viability were examined by MTT assay and colony formation assay. Cell cycle distribution and apoptosis were detected by flow cytometry. Expressions of p53, p21, and FAS protein levels were assessed by Western blotting. CRC cells transfected with lncRNA-shRNA were injection into nude mice to identify the function of lncRNA-ROR on tumorigenesis in vivo. RESULTS The expression level of lncRNA-ROR was elevated in CRC tissues when compared to adjacent tissues (n=78). lncRNA-ROR knockdown significantly suppressed cell proliferation and viability, while lncRNA-ROR overexpression had the opposite effect. Decreased lncRNA-ROR expression enhanced cell apoptosis and triggered cell cycle arrest in G0/G1 phase, while elevated lncRNA-ROR expression presented the opposite effect. Protein levels of p53 and p53 target genes were affected by lncRNA-ROR in vitro, and downregulation of lncRNA-ROR impeded tumorigenesis in vivo. CONCLUSIONS Our study demonstrates that lncRNA-ROR participates in controlling CRC proliferation, viability, and apoptosis, partially by modulating p53, which provides potential and prospective therapeutic targets for CRC.