Long noncoding RNA TSLNC8 is a tumor suppressor that inactivates the interleukin-6/STAT3 signaling pathway

The Functional Role of Long Non-Coding RNAs in Melanoma

Melanoma is the most lethal skin cancer, with increasing incidence worldwide. The molecular events that drive melanoma development and progression have been extensively studied, resulting in significant improvements in diagnostics and therapeutic approaches. However, a high drug resistance to targeted therapies and adverse effects of immunotherapies are still a major challenge in melanoma treatment. Therefore, the elucidation of molecular mechanisms of melanomagenesis and cancer response to treatment is of great importance. Recently, many studies have revealed the close association of long noncoding RNAs (lncRNAs) with the development of many cancers, including melanoma. These RNA molecules are able to regulate a plethora of crucial cellular processes including proliferation, differentiation, migration, invasion and apoptosis through diverse mechanisms, and even slight dysregulation of their expression may lead to tumorigenesis. lncRNAs are able to bind to protein complexes, DNA and RNAs, affecting their stability, activity, and localization. They can also regulate gene expression in the nucleus. Several functions of lncRNAs are context-dependent. This review summarizes current knowledge regarding the involvement of lncRNAs in melanoma. Their possible role as prognostic markers of melanoma response to treatment and in resistance to therapy is also discussed.

The lncRNA VPS9D1-AS1 Promotes Hepatocellular Carcinoma Cell Cycle Progression by Regulating the HuR/CDK4 Axis

Long noncoding RNAs (lncRNAs) represent promising therapeutic targets associated with hepatocellular carcinoma (HCC). lncRNA VPS9D1 antisense RNA 1 (VPS9D1-AS1) regulates colon and prostate cancer, but its relevance in HCC remains to be clarified. Using microarray data from the NCBI Gene Expression Omnibus (GEO) database (GSE65485) and The Cancer Genome Atlas (TCGA) database, VPS9D1-AS1 expression in HCC and normal liver tissue sample HCC were compared. Relative lncRNA expression was also measured through real-time quantitative PCR (qPCR) in 80 pairs of HCC tumor and paracancerous tissues and in human HCC cell lines. VPS9D1-AS1 knockdown was achieved by transfecting these HCC cells with a specific siRNA construct in vitro, and the proliferation of these cells was quantified through cell proliferation assays and colony formation assays, while flow cytometry was employed to assess their cell cycle progression. The role of the VPS9D1-AS1 lncRNA as a regulator of HCC tumorigenesis was also assessed in vivo by subcutaneously implanting BALB/c nude mice with HepG2 cells stably expressing either sh-VPS9D1-AS1 or a control shRNA construct. Mechanistic analyses were additionally conducted by examining in vitro CDK4 and HuR expression through western blotting and qPCR. VPS9D1-AS1 expression was significantly increased in HCC tissues in the analyzed databases and our independent tissue samples. Elevated VPS9D1-AS1 expression was related to larger tumor size and more advanced tumor, node, metastasis (TNM) stage, and HCC patients expressing higher levels of this lncRNA exhibited poorer survival outcomes. Knocking down VPS9D1-AS1 impaired the proliferative and colony formation activity of HepG2 cells while promoting their apoptotic death. Consistently, VPS9D1-AS1 silencing suppressed HCC tumor growth in vivo. Mechanistically, VPS9D1-AS1 was able to bind to the HuR protein and thereby influence the stability and expression of the CDK4 mRNA, thus impacting HCC cell proliferation. The VPS9D1-AS1/HuR/CDK4 signaling axis regulates HCC tumor cell oncogenic activity, highlighting this pathway as a promising therapeutic target.

RP11-616M22.7 recapitulates imatinib resistance in gastrointestinal stromal tumor

Emerging evidence has shown that long non-coding RNAs (lncRNAs) play crucial roles in human cancers. However, systematic characterization of lncRNAs and their roles in gastrointestinal stromal tumor (GIST) therapy have been lacking. We performed high-throughput RNA sequencing (RNA-seq) of 20 GIST and paired adjacent normal samples. We characterized the transcriptional landscape and dysregulation of lncRNAs in GIST. We identified 866 upregulated and 1,268 downregulated lncRNAs in GIST samples, the majority of which were GIST-specific over other cancer types. Most hallmarks were found to be dysregulated in GIST samples, and lncRNAs were highly associated with cancer-related hallmarks. RP11-616M22.7 was identified to increase in imatinib-resistant samples compared to those in non-resistant samples. Further analysis revealed that RP11-616M22.7 was closely associated with the Hippo signaling pathway. By treating GIST cells with different doses of imatinib, we verified that RP11-616M22.7 knockdown promotes the sensitivity of tumor cells, whereas RP11-616M22.7 overexpression induces resistance to imatinib. We further confirmed reducing of resistance to imatinib by knocking down RP11-616M22.7 in vivo. Additionally, RP11-616M22.7 was observed to interact with RASSF1 protein. Our study revealed that deficiency of RP11-616M22.7 was able to reduce resistance of the GIST cell response to imatinib treatment both in vitro and in vivo.

Ovarian cancer: epigenetics, drug resistance, and progression

Ovarian cancer (OC) is one of the most common malignant tumors in women. OC is associated with the activation of oncogenes, the inactivation of tumor suppressor genes, and the activation of abnormal cell signaling pathways. Moreover, epigenetic processes have been found to play an important role in OC tumorigenesis. Epigenetic processes do not change DNA sequences but regulate gene expression through DNA methylation, histone modification, and non-coding RNA. This review comprehensively considers the importance of epigenetics in OC, with a focus on microRNA and long non-coding RNA. These types of RNA are promising molecular markers and therapeutic targets that may support precision medicine in OC. DNA methylation inhibitors and histone deacetylase inhibitors may be useful for such targeting, with a possible novel approach combining these two therapies. Currently, the clinical application of such epigenetic approaches is limited by multiple obstacles, including the heterogeneity of OC, insufficient sample sizes in reported studies, and non-optimized methods for detecting potential tumor markers. Nonetheless, the application of epigenetic approaches to OC patient diagnosis, treatment, and prognosis is a promising area for future clinical investigation.

Keep your eyes peeled for long noncoding RNAs: Explaining their boundless role in cancer metastasis, drug resistance, and clinical application

Cancer metastasis and drug resistance are two major obstacles in the treatment of cancer and therefore, the leading cause of cancer-associated mortalities worldwide. Hence, an in-depth understanding of these processes and identification of the underlying key players could help design a better therapeutic regimen to treat cancer. Earlier thought to be merely transcriptional junk and having passive or secondary function, recent advances in the genomic research have unravelled that long noncoding RNAs (lncRNAs) play pivotal roles in diverse physiological as well as pathological processes including cancer metastasis and drug resistance. LncRNAs can regulate various steps of the complex metastatic cascade such as epithelial-mesenchymal transition (EMT), invasion, migration and metastatic colonization, and also affect the sensitivity of cancer cells to various chemotherapeutic drugs. A substantial body of literature for more than a decade of research evince that lncRNAs can regulate gene expression at different levels such as epigenetic, transcriptional, posttranscriptional, translational and posttranslational levels, depending on their subcellular localization and through their ability to interact with DNA, RNA and proteins. In this review, we mainly focus on how lncRNAs affect cancer metastasis by modulating expression of key metastasis-associated genes at various levels of gene regulation. We also discuss how lncRNAs confer cancer cells either sensitivity or resistance to various chemo-therapeutic drugs via different mechanisms. Finally, we highlight the immense potential of lncRNAs as prognostic and diagnostic biomarkers as well as therapeutic targets in cancer.

Heparin-binding growth factor (HDGF) drives radioresistance in breast cancer by activating the STAT3 signaling pathway

Although reports implicate radioresistance as an important obstacle for the management of breast cancer, its molecular mechanism is elusive. Herein, we found that high HDGF levels are expressed significantly in breast cancer and exhibit a positive association with poor survival prognosis. Heparin-binding growth factor (HDGF) was upregulated in radioresistant breast cancer cells, however, its knockdown could reduce breast cancer radioresistant both in vitro and in vivo. Additionally, the binding of RXRα to HDGF promoter blocked HDGF transcriptional activity, consequently inhibiting breast cancer radioresistance. The enhanced radioresistant activity of HDGF is induced by TKT and STAT3, impacting the STAT3-Tyr705 and STAT3-Ser727 phosphorylation and STAT3 transcriptional activity. Notably, HDGF depletion renders radioresistant hypersensitive to the drug that targets STAT3 phosphorylation. This article demonstrates the novel function of HDGF as a promising molecular target for predicting radioresistance in breast cancer.

Caveolin-1 Deficiency Induces Atrial Fibrosis and Increases Susceptibility to Atrial Fibrillation by the STAT3 Signaling Pathway

ABSTRACT

Atrial fibrillation (AF) is a common arrhythmia in the clinic. Ablation failure and recurrence after cardioversion have become medical problems worldwide. An important pathological feature of AF is atrial fibrosis, which increases susceptibility to AF. As an important target of fibrosis signal integration, the signal transducer and activator of transcription 3 (STAT3) signaling pathway plays an important role in fibrosis. Caveolin-1 (CAV1), a cell membrane protein, is involved in a variety of the biological functions of cells. However, the role of CAV1 in atrial fibrosis remains unclear. In this study, Masson's trichrome staining was used to detect the degree of atrial fibrosis, and the expression of CAV1 in the human atrium was evaluated by immunohistochemistry. To further study the role of CAV1, its expression in cultured rat atrial fibroblasts was silenced using siRNAs. Atrial fibroblasts were treated with angiotensin II to observe the effects on CAV1 and the transforming growth factor-β1 and STAT3 signaling pathways. We also detected the effects of CAV1 scaffolding domain (CSD) peptide on fibrosis through the addition of exogenous CSD peptide. The results showed that CAV1 expression decreased with the aggravation of atrial fibrosis and that this effect increased the incidence of AF. The depletion of CAV1 induced excessive extracellular matrix deposition by activating the STAT3 and transforming growth factor-β1/SMAD2 signaling pathways, and this effect was exacerbated by stimulation with angiotensin II and improved by CSD peptide. These data suggested that CAV1 not only plays a critical role in fibrosis progression but also provides a target for the treatment of atrial fibrosis and AF.

RNA sequencing identifies two novel liver-specific long noncoding RNAs with potential diagnostic value in hepatocellular carcinoma

Aim: To explore the expression profiles of long noncoding RNAs (lncRNAs) and identify novel lncRNAs as biomarkers for early diagnosis and therapy of hepatocellular carcinoma (HCC). Materials & methods: Expression profiles of lncRNAs and mRNAs in five paired HCC and adjacent normal tissues were obtained by RNA sequencing. Eight lncRNAs, including two novel liver-specific lncRNAs (NONHSAT059247.2 and NONHSAT013897.2), were validated in another 74 pairs of HCC and adjacent normal tissues by quantitative reverse transcription PCR. Results: The results of quantitative reverse transcription PCR showed that NONHSAT252133.1, NONHSAT112116.2 and NONHSAT242657.1 were significantly upregulated in HCC tissues, whereas NONHSAT169790.1, NONHSAT059247.2 and NONHSAT013897.2 were significantly downregulated. Two liver-specific lncRNAs demonstrated excellent diagnostic performance: NONHSAT059247.2 (area under the curve = 0.941, 95% CI: 0.902-0.979, p < 0.0001), NONHSAT013897.2 (area under the curve = 0.944, 95% CI: 0.906-0.983, p < 0.0001). Conclusion: The liver-specific lncRNAs NONHSAT059247.2 and NONHSAT013897.2, may provide new biomarkers for the future study on diagnosis, therapy and mechanisms of HCC.

Uncovering the RNA-binding protein landscape in the pluripotency network of human embryonic stem cells

Embryonic stem cell (ESC) self-renewal and cell fate decisions are driven by a broad array of molecular signals. While transcriptional regulators have been extensively studied in human ESCs (hESCs), the extent to which RNA-binding proteins (RBPs) contribute to human pluripotency remains unclear. Here, we carry out a proteome-wide screen and identify 810 proteins that bind RNA in hESCs. We reveal that RBPs are preferentially expressed in hESCs and dynamically regulated during early stem cell differentiation. Notably, many RBPs are affected by knockdown of OCT4, a master regulator of pluripotency, several dozen of which are directly targeted by this factor. Using cross-linking and immunoprecipitation (CLIP-seq), we find that the pluripotency-associated STAT3 and OCT4 transcription factors interact with RNA in hESCs and confirm the binding of STAT3 to the conserved NORAD long-noncoding RNA. Our findings indicate that RBPs have a more widespread role in human pluripotency than previously appreciated.

Long non-coding RNA TINCR promotes hepatocellular carcinoma proliferation and invasion via STAT3 signaling by direct interacting with T-cell protein tyrosine phosphatase (TCPTP)

The long non-coding RNAs (lncRNAs) participate in modulating numerous important cancer phenotypes via formation of RNA-protein complex. TINCR (terminal differentiation-induced lncRNA) modulates cancer cell behavior in many human malignancies, such as hepatocellular carcinoma (HCC). Herein, we proposed to investigate the underlying mechanism by which TINCR regulates HCC progression via formation of RNA-protein. RNA pulldown, LC-MS/MS, bioinformatics analysis, and RNA immunoprecipitation (RIP) assays were employed to identify TINCR-interacting protein TCPTP in HCC cells. The siRNAs for TINCR and TCPTP were transfected into HCC cells. The plasmids encoding full length or the 1–360 nt deletion of TINCR were generated and applied to cell transfection. The CCK-8, colony formation, EdU, wound healing along with transwell assays were employed to examine cell proliferation, apoptosis, migration, and infiltration. Real-time PCR, as well as western blot assays were employed to assess the levels of STAT3 phosphorylation and its target genes. We identified 1–360 nt region of TINCR, which directly bound with the phosphatase domain of TCPTP to inhibit its tyrosine phosphatase activity. Then, the results showed that the increasing of cell growth, migration, infiltration, and the reducing of apoptosis in TINCR-knockdown HCC cells was remarkably reversed with TCPTP silence. Additionally, Δ1-360 TINCR overexpression did not affect HCC cell growth, apoptosis, migration, infiltration, and STAT3 target genes expression. Our data revealed that TINCR directly bound TCPTP and suppressed the dephosphorylation of STAT3, thus promoting STAT3 activation and its downstream target genes in HCC progression and tumorigenicity.

Highlights

LncRNA TINCR interacted with protein TCPTP

LncRNA TINCR maintained STAT3 phosphorylation

LncRNA TINCR affected STAT3 signaling in HCC

Abbreviations:

lncRNAs: long non-coding RNAs; TINCR: terminal differentiation-induced lncRNA; TCPTP: T cell protein tyrosine phosphatase; siRNA: small-interfering RNA; HCC: hepatocellular carcinoma; nt: nucleotide; LC-MS/MS: Liquid Chromatography - Tandem Mass Spectrometry; RIP: RNA immunoprecipitation; ANOVA: analysis of variance; EdU: 5-ethynyl-2’-deoxyuridine; real-time PCR: real-time polymerase chain reaction; CCK-8: cell counting kit-8; aa: amino acids; STAT3: signal transducer and activator of transcription 3

Paradoxical functions of long noncoding RNAs in modulating STAT3 signaling pathway in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the lethal and leading types of cancer threatening the globe with a high mortality rate. STAT3 is an oncogenic transcription factor that is aberrantly activated in several human malignancies including HCC. Many STAT3-driven genes control cell proliferation and survival, apoptotic resistance, cell cycle progression, metastasis, and chemotherapeutic resistance. STAT3 signaling is regulated by endogenous modulators such as protein tyrosine phosphatase (PTP), suppressor of cytokine signaling (SOCS), protein inhibitor of activated STAT (PIAS), and various long noncoding RNAs (lncRNAs). Interestingly, lncRNAs have been reported to exhibit oncogenic and tumor suppressor functions, and these effects are mediated through diverse molecular mechanisms including sponging of microRNAs (miRs), transcription activation/inhibition, and epigenetic modifications. In this article, we have discussed the possible role of STAT3 signaling in hepatocarcinogenesis and various mechanisms by which lncRNAs impart their oncogenic or tumor suppressive action by modulating the STAT3 pathway in HCC.

Missing links - epigenetic regulators of the pancreatic cancer-associated inflammation

Pancreatic ductal adenocarcinoma (PDAC) features a hostile tumor microenvironment (TME) that renders it remarkably resistant to most therapeutic interventions. Consequently, survival remains among the poorest compared with other gastrointestinal cancers. Concerted efforts are underway to decipher the complex PDAC TME, break down barriers to efficacious therapies and identify novel treatment strategies. In the recent Clinical Science, Li and colleagues identify the long noncoding RNA KLHDC7B-DT as a crucial epigenetic regulator of IL-6 transcription in PDAC and illustrate its potent influences on the pancreatic TME. In this commentary, we introduce epigenetics in pancreatic cancer and put the findings by Li et al. in context with current knowledge.

LINC00261: a burgeoning long noncoding RNA related to cancer

Long noncoding RNAs (lncRNAs), are transcripts longer than 200 nucleotides that are considered to be vital regulators of many cellular processes, particularly in tumorigenesis and cancer progression. long intergenic non-protein coding RNA 261 (LINC00261), a recently discovered lncRNA, is abnormally expressed in a variety of human malignancies, including pancreatic cancer, gastric cancer, colorectal cancer, lung cancer, hepatocellular carcinoma, breast cancer, laryngeal carcinoma, endometrial carcinoma, esophageal cancer, prostate cancer, choriocarcinoma, and cholangiocarcinoma. LINC00261 mainly functions as a tumor suppressor that regulates a variety of biological processes in the above-mentioned cancers, such as cell proliferation, apoptosis, motility, chemoresistance, and tumorigenesis. In addition, the up-regulation of LINC00261 is closely correlated with both favorable prognoses and many clinical characteristics. In the present review, we summarize recent research documenting the expression and biological mechanisms of LINC00261 in tumor development. These findings suggest that LINC00261, as a tumor suppressor, has bright prospects both as a biomarker and a therapeutic target.

LncRNA TUG1 silencing enhances proliferation and migration of ox-LDL-treated human umbilical vein endothelial cells and promotes atherosclerotic vascular injury repairing via the Runx2/ANPEP axis

The role of vascular endothelial cell injury in the course of atherosclerosis (AS) has attracted increasing attention. Long non-coding RNAs (LncRNAs) are demonstrated to be the biomarker for the diagnosis of AS. This study investigated the mechanism of lncRNA taurine upregulated gene 1 (TUG1) in AS. Microarray data of AS obtained from GEO database showed that lncRNA TUG1 was differentially expressed in AS samples. TUG1 expression was upregulated in ox-LDL-treated human umbilical vein endothelial cells (HUVECs). Oxidized low density lipoprotein (ox-LDL)-treated HUVECs were then transfected with sh-TUG1. TUG1 silencing promoted proliferation and migration of ox-LDL-treated HUVECs. TUG1 bound to Runt-related transcription factor 2 (Runx2). Runx2 silencing promoted proliferation and migration of HUVECs. The downstream genes of Runx2 were predicted by hTFtarget database. The binding site of Runx2 and Aminopeptidase N (ANPEP) was determined. Runx2 silencing reversed the repression effect of overexpressing ANPEP on cell proliferation and migration. TUG1 silencing inhibited ANPEP expression via Runx2 to promote HUVEC proliferation and migration. A mouse model of AS was established. The area of atherosclerotic lesions of mouse aorta was detected, and vascular re-endothelialization was evaluated. TUG1 silencing promoted vascular injury repairing and inhibited AS in vivo. In conclusion, TUG1 silencing enhanced proliferation and migration of ox-LDL-treated HUVECs and promoted vascular injury repairing in vivo via the Runx2/ANPEP axis.

The Impact of Long Non-Coding RNAs in the Pathogenesis of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is among the utmost deadly human malignancies. This type of cancer has been associated with several environmental, viral, and lifestyle risk factors. Among the epigenetic factors which contribute in the pathogenesis of HCC is dysregulation of long non-coding RNAs (lncRNAs). These transcripts modulate expression of several tumor suppressor genes and oncogenes and alter the activity of cancer-related signaling axes. Several lncRNAs such as NEAT1, MALAT1, ANRIL, and SNHG1 have been up-regulated in HCC samples. On the other hand, a number of so-called tumor suppressor lncRNAs namely CASS2 and MEG3 are down-regulated in HCC. The interaction between lncRNAs and miRNAs regulate expression of a number of mRNA coding genes which are involved in the pathogenesis of HCC. H19/miR-15b/CDC42, H19/miR-326/TWIST1, NEAT1/miR-485/STAT3, MALAT1/miR-124-3p/Slug, MALAT1/miR-195/EGFR, MALAT1/miR-22/SNAI1, and ANRIL/miR-144/PBX3 axes are among functional axes in the pathobiology of HCC. Some genetic polymorphisms within non-coding regions of the genome have been associated with risk of HCC in certain populations. In the current paper, we describe the recent finding about the impact of lncRNAs in HCC.

Tumor microenvironment acidity modulates ROR1 to promote epithelial-mesenchymal transition and hepatocarcinoma metastasis

The tendency of hepatocarcinoma to metastasize results in a high rate of mortality, making it a hot research topic in cancer studies. Although an acidic tumor microenvironment has been proven to promote cancer metastasis, the underlying regulatory mechanisms remain poorly defined. Here, we found that acidic conditions significantly enhanced cell migration and invasion ability in hepatocellular carcinoma, and the expression of receptor tyrosine kinase-like orphan receptor 1 (ROR1) was distinctly upregulated in acid-treated cells. In addition, siRNA-mediated knockdown of ROR1 could effectively inhibit acid-induced cell migration, invasion and epithelial-mesenchymal transition (EMT). Importantly, neutralization of acidic environments with NaHCO3 could downregulate acid-stimulated ROR1 expression, thereby retarding cell metastatic potential. Notably, the formation of metastatic nodules was significantly increased after intrapulmonary injection of acid-stimulated cancer cells, and this was inhibited by pretreating with NaHCO3. In summary, we reveal that an acidic tumor microenvironment modulates ROR1 expression to promote tumor metastasis, providing not only a better understanding of molecular mechanisms related to metastasis, but also a promising target for tumor management.

Dual role of inositol-requiring enzyme 1α (IRE-1α) in Cd-induced apoptosis in human renal tubular epithelial cells: Endoplasmic reticulum stress and STAT3 signaling activation

Cadmium (Cd) is a nephrotoxicant that primarily damages renal proximal tubular cells. Endoplasmic reticulum (ER) stress is mechanistically linked to Cd-induced renal injury. Inositol-requiring enzyme 1 (IRE-1α) is the most conserved ER stress transducer protein, which has both kinase and endonuclease activities. This study aimed to investigate whether the two enzymatic activities of IRE-1α have different effects in its regulation of Cd-induced apoptosis. Human proximal tubular (HK-2) cells were treated with 20 μM CdCl₂ for 0-24 h, and mice were fed with Cd-containing drinking water (100-400 mg/L) for 24 weeks. We found that Cd increased cell apoptosis in HK-2 cells and mouse kidneys in a time-dependent manner. Such cytotoxicity was correlated with activation of ER stress, evidenced by upregulation of IRE-1α and its target protein spliced X-box binding protein-1 (XBP-1 s). Interestingly, inhibition of IRE-1α kinase activity by KIRA6 was more protective against Cd-induced apoptosis than inhibition of its RNase activity by STF-083010. Mechanistically, Cd promoted the binding of IRE-1α with signal transducer and activator of transcription-3 (STAT3) leading to elevated phosphorylation of STAT3 at Ser727 and thus inactivation of STAT3 signaling, which resulted in aggravation of Cd-induced apoptosis in HK-2 cells. Collectively, our findings indicate that IRE-1α coordinate ER stress and STAT3 signaling in mediating Cd-induced renal toxicity, suggesting that targeting IRE-1α might be a potential therapeutic approach for Cd-induced renal dysfunction and disease.

Genome-wide DNA methylation and RNA expression differences correlate with invasiveness in melanoma cell lines

Aims & objectives: The aim of this study was to investigate the role of DNA methylation in invasiveness in melanoma cells. Materials & methods: The authors carried out genome-wide transcriptome (RNA sequencing) and reduced representation bisulfite sequencing methylome profiling between noninvasive (n = 4) and invasive melanoma cell lines (n = 5). Results: The integration of differentially expressed genes and differentially methylated fragments (DMFs) identified 12 DMFs (two in AVPI1, one in HMG20B, two in BCL3, one in NTSR1, one in SYNJ2, one in ROBO2 and four in HORMAD2) that overlapped with either differentially expressed genes (eight DMFs and six genes) or cis-targets of lncRNAs (five DMFs associated with cis-targets and four differentially expressed lncRNAs). Conclusions: DNA methylation changes are associated with a number of transcriptional differences observed in noninvasive and invasive phenotypes in melanoma.

Linc-KILH potentiates Notch1 signaling through inhibiting KRT19 phosphorylation and promotes the malignancy of hepatocellular carcinoma

Long noncoding RNAs (LncRNAs) are emerging as crucial regulators in the pathophysiological process of various tumors, including HCC. Here, we identify a novel lncRNA Linc-KILH (KRT19 interacting long noncoding RNA in hepatocellular carcinoma), which is significantly up-regulated in HCC tissues and positively correlated with larger tumor size, severer microvascular invasion, more intrahepatic metastasis and decreased survival of HCC patients. Silence of Linc-KILH remarkably inhibited the proliferation and metastasis abilities of KRT19-positive HCC cells in vitro and in vivo. Mechanistically, Linc-KILH interacts with KRT19 and then inhibits the phosphorylation of KRT19 on Ser35, thereby, enhancing the translocation of KRT19 from cytoplasm to membrane in KRT19 positive HCC cells. Additionally, we validated that KRT19 interacts with β-catenin but not RAC1 in HCC cells. Linc-KILH enhanced the interaction between β-catenin and KRT19 in cytoplasm and promoted the nuclear translocation of β-catenin in HCC cells. Furthermore, Linc-KILH could enhance the promoting function of KRT19 on Notch1 signaling with the existence of KRT19 in HCC cells. Collectively, we revealed that Linc-KILH exerts a vital function in KRT19 positive HCC progression and may likely be developed into an effective therapeutic target for HCC.

Long non-coding RNA CCDC183-AS1 acts AS a miR-589-5p sponge to promote the progression of hepatocellular carcinoma through regulating SKP1 expression

Background

Hepatocellular carcinoma (HCC) is a common type of malignant human cancer with high morbidity and poor prognosis, causing numerous deaths per year worldwide. Growing evidence has been demonstrated that long non-coding RNAs (lncRNAs) are closely associated with hepatocarcinogenesis and metastasis. However, the roles, functions, and working mechanisms of most lncRNAs in HCC remain poorly defined.

Methods

Real-time quantitative polymerase chain reaction (qRT-PCR) was used to detect the expression level of CCDC183-AS1 in HCC tissues and cell lines. Cell proliferation, migration and invasion ability were evaluated by CCK-8 and transwell assay, respectively. Animal experiments were used to explore the role of CCDC183-AS1 and miR-589-5p in vivo. Bioinformatic analysis, dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were performed to confirm the regulatory relationship between CCDC183-AS1, miR-589-5p and SKP1.

Results

Significantly upregulated expression of CCDC183-AS1 was observed in both HCC tissues and cell lines. HCC patients with higher expression of CCDC183-AS1 had a poorer overall survival rate. Functionally, overexpression of CCDC183-AS1 markedly promoted HCC cell proliferation, migration and invasion in vitro and tumor growth and metastasis in vivo, whereas the downregulation of CCDC183-AS1 exerted opposite effects. MiR-589-5p inhibitor counteracted the proliferation, migration and invasion inhibitory effects induced by CCDC183-AS1 silencing. Mechanistically, CCDC183-AS1 acted as a ceRNA through sponging miR-589-5p to offset its inhibitory effect on the target gene SKP1, then promoted the tumorigenesis of HCC.

Conclusions

CCDC183-AS1 functions as an oncogene to promote HCC progression through the CCDC183-AS1/miR-589-5p/SKP1 axis. Our study provided a novel potential therapeutic target for HCC patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01861-6.

A 5-lncRNA Signature Associated with Smoking Predicts the Overall Survival of Patients with Muscle-Invasive Bladder Cancer

Increasing evidence demonstrated that noncoding RNA is abnormally expressed in cancer tissues and serves a vital role in tumorigenesis, tumor development, and metastasis. The aim of the present study was to determine an lncRNA signature in order to predict the overall survival (OS) of patients with muscle-invasive bladder cancer (MIBC). A total of 246 patients with pathologically confirmed MIBC in The Cancer Genome Atlas (TCGA) dataset were recruited and included in the present study. We choose patients who have smoked less (including never smoking) or more than 15 years. A total of 44 differentially expressed lncRNAs were identified with a fold change larger than 1.5 and a P value < 0.05 through the limma package. Subsequently, a comparison between patients with no tobacco smoke exposure for <15 years and patients who had been exposed to tobacco smoke for >15 years was performed by using the matchIt package. Among the 44 differentially expressed lncRNAs, 5 lncRNAs were identified to be significantly associated with OS. Based on the characteristic risk scores of these 5 lncRNAs, patients were divided into low-risk and high-risk groups and exhibited significant differences in OS. Multivariate Cox regression analysis demonstrated that the 5-lncRNA signature was independent of age, tumor-node metastasis (TNM) staging, lymphatic node status, and adjuvant postoperative radiotherapy. In the present study, a novel 5-lncRNA signature was developed and was demonstrated to be useful in predicting the survival of patients with MIBC. If validated, this lncRNA signature may assist in the selection of a high-risk subpopulation that requires more aggressive therapeutic intervention. The risk scores involved in several associated pathways were identified using gene set enrichment analysis (GSEA). However, the clinical implications and mechanism of these 5 lncRNAs require further investigation.

DMP-1 promoter-associated antisense strand non-coding RNA, panRNA-DMP-1, physically associates with EGFR to repress EGF-induced squamous cell carcinoma migration

Accumulating evidence suggests that specific non-coding RNAs exist in many types of malignant tissues, and are involved in cancer invasion and metastasis. However, little is known about the precise roles of non-coding RNAs in squamous cell carcinoma (SQCC) invasion and migration. Recently, the dentin matrix protein-1 (DMP-1) gene locus was identified as a transcriptionally active site in squamous cell carcinoma (SQCC) tissue and cells. However, it is unclear whether RNA associated with cell migration exist at the DMP-1 gene locus in SQCC cells. We identified a novel promoter-associated non-coding RNA in the antisense strand of DMP-1 gene locus, promoter-associated non-coding RNA (panRNA)-DMP-1, by the RACE method in SQCC cells and tissues, and characterized the functions of panRNA-DMP-1 in EGF-driven SQCC cell migration. The inhibition of endogenous panRNA-DMP-1 expression by specific siRNAs and exogenous over-expression of panRNA-DMP-1 resulted in increased and suppressed cellular migration toward EGF in SQCC cells, respectively, and nuclear expression of panRNA-DMP-1 was induced by EGF stimulation. Mechanistically, suppression of panRNA-DMP-1 expression increased EGFR nuclear localization upon EGF treatment and nuclear panRNA-DMP-1 physically interacted with EGFR, which was confirmed by RNA immunoprecipitation assay using a bacteriophage-delivered PP7 RNA labeling system. Furthermore, co-immunoprecipitation assay revealed that suppression of panRNA-DMP-1 stabilized EGFR interaction with STAT3, a known co-transcription factors of EGFR, to induce migratory properties in many cancer cells. Based on these findings, panRNA-DMP-1 is an EGFR-associating RNA that inhibits the EGF-induced migratory properties of SQCC possibly by regulating EGFR nuclear localization and EGFR binding to STAT3.

Dual relationship between long non-coding RNAs and STAT3 signaling in different cancers: New insight to proliferation and metastasis

Uncontrolled growth and metastasis of cancer cells is an increasing challenge for overcoming cancer, and improving survival of patients. Complicated signaling networks account for proliferation and invasion of cancer cells that need to be elucidated for providing effective cancer therapy, and minimizing their malignancy. Long non-coding RNAs (lncRNAs) are RNA molecules with a length of more than 200 nucleotides. They participate in cellular events, and their dysregulation in a common phenomenon in different cancers. Noteworthy, lncRNAs can regulate different molecular pathways, and signal transducer and activator of transcription 3 (STAT3) is one of them. STAT3 is a tumor-promoting factors in cancers due to its role in cancer proliferation (cell cycle progression and apoptosis inhibition) and metastasis (EMT induction). LncRNAs can function as upstream mediators of STAT3 pathway, reducing/enhancing its expression. This dual relationship is of importance in affecting proliferation and metastasis of cancer cells. The response of cancer cells to therapy such as chemotherapy and radiotherapy is regulated by lncRNA/STAT3 axis. Tumor-promoting lncRNAs including NEAT1, SNHG3 and H19 induces STAT3 expression, while tumor-suppressing lncRNAs such as MEG3, PTCSC3 and NKILA down-regulate STAT3 expression. Noteworthy, upstream mediators of STAT3 such as microRNAs can be regulated by lncRNAs. These complicated signaling networks are mechanistically described in the current review.

Non-coding RNAs rewire cancer metabolism networks

Non-coding RNAs (ncRNAs) are functional RNAs with limited or no protein-coding ability. These interact with their target molecules and participate in the precise regulation of disease development. Metabolic reprogramming is a hallmark in cancer, and is considered essential in meeting increased macromolecular biosynthesis and energy generation of tumors. Recent studies have revealed the involvement of ncRNAs in several metabolic regulations of cancer through direct modulation of metabolic enzyme activities or participation of metabolism-related signaling pathways. Elucidation of how ncRNAs regulate metabolic reprogramming of cancers has opened up a novel intention to understand the mechanism of metabolic rewiring and also the opportunities of utilizing ncRNA-based therapeutics for targeting the metabolism in cancer treatment.

Downregulation of lncRNA TSLNC8 promotes melanoma resistance to BRAF inhibitor PLX4720 through binding with PP1α to re-activate MAPK signaling

PURPOSE

Approximately 60% of patients with melanoma harbor BRAF mutation and targeting BRAF offers enormous advance in the treatment of those patients. Unfortunately, the efficacy of the BRAF inhibitors is usually restricted by the onset of drug resistance. Therefore, better understanding of the adaptive drug resistance mechanisms is essential for the development of alternative therapeutic strategies, and offers more promising measures to promote the short duration of response to BRAF inhibitors.

METHODS

The levels of tumor suppressive long noncoding RNA on chromosome 8p12 (TSLNC8) were evaluated by qPCR. The MTT assay, colony formation assay, apoptosis assay, and in vivo xenograft tumor model were performed to assess the functions of TSLNC8 on drug resistance. Western blotting, RNA pull-down, and RNA immunoprecipitation (RIP) assays were applied to investigate the mechanisms of TSLNC8 in melanoma.

RESULTS

Herein, our findings demonstrate that TSLNC8 is significantly downregulated in BRAF inhibitor-resistant melanoma tissues and cells. Moreover, downregulation of TSLNC8 in BRAF inhibitor sensitive cells reduces the toxicity response to BRAF inhibitor PLX4720, and inhibits apoptosis of melanoma cells-treated with PLX4720. Further assay elucidates that TSLNC8 can bind with the catalytic subunit of protein phosphatase 1α (PP1α) to regulate its distribution, and Downregulation of TSLNC8 results in PP1α cytoplasmic accumulation, thus re-activating the MAPK signaling. Eventually, the overexpression of TSLNC8 in BRAF inhibitor PLX4720-resistant melanoma cells restores the sensitive to BRAF inhibitor.

CONCLUSION

Collectively, our research provides a compelling rationale for resistance to BRAF inhibitor in melanoma, and the patient might benefit from the combinatorial therapy of BRAF inhibitors and lncRNA TSLNC8.

Comprehensive analysis of key lncRNAs in HCV-positive hepatocellular carcinoma

INTRODUCTION

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. Despite the therapeutic advances in HCC in the past few decades, the mortality rate of HCC is still high. Hepatitis C (HCV) infection is one of the major etiological risk factors of HCCs. However, the underlying mechanisms of HCV-induced hepatocarcinogenesis remain largely unclear.

MATERIAL AND METHODS

Our study represented the comprehensive analysis of differentially expressed lncRNAs in HCV-positive HCC for the first time by analyzing the public dataset GSE17856. Co-expression network and gene ontology (GO) analysis revealed the functions of those differentially expressed lncRNAs.

RESULTS

We identified 256 upregulated lncRNAs and 198 downregulated lncRNAs in HCV- positive HCC compared to the normal liver tissues. Co-expression network and GO analysis showed that these lncRNAs were involved in regulating metabolism, energy pathways, proliferation and the immune response. Seven lncRNAs (LOC341056, CCT6P1, PTTG3P, LOC643387, LOC100133920, C3P1 and C22orf45) were identified as key lncRNAs and co-expressed with more than 100 differentially expressed genes (DEGs) in HCV-related HCC. Kaplan-Meier analysis showed that higher expression levels of LOC643387, PTTG3P, LOC341056, CCT6P1 and lower expression levels of C3P1 and C22orf45 were associated with shorter survival time in the TCGA dataset.

CONCLUSIONS

We believe that this study can provide novel potential therapeutic and prognostic biomarkers for HCV-positive HCC.

The pleiotropic role of transcription factor STAT3 in oncogenesis and its targeting through natural products for cancer prevention and therapy

Signal transducer and activator of transcription 3 (STAT3) is one of the crucial transcription factors, responsible for regulating cellular proliferation, cellular differentiation, migration, programmed cell death, inflammatory response, angiogenesis, and immune activation. In this review, we have discussed the classical regulation of STAT3 via diverse growth factors, cytokines, G-protein-coupled receptors, as well as toll-like receptors. We have also highlighted the potential role of noncoding RNAs in regulating STAT3 signaling. However, the deregulation of STAT3 signaling has been found to be associated with the initiation and progression of both solid and hematological malignancies. Additionally, hyperactivation of STAT3 signaling can maintain the cancer stem cell phenotype by modulating the tumor microenvironment, cellular metabolism, and immune responses to favor drug resistance and metastasis. Finally, we have also discussed several plausible ways to target oncogenic STAT3 signaling using various small molecules derived from natural products.

Decreased expression of the long non-coding RNA HOXD-AS2 promotes gastric cancer progression by targeting HOXD8 and activating PI3K/Akt signaling pathway

BACKGROUND

Long non-coding RNAs (lncRNAs) have been shown to be associated with many tumors. However, the specific mechanism of lncRNAs in the occurrence and development of gastric cancer (GC) has not been fully elucidated.

AIM

To explore the expression level and molecular mechanism of HOXD-AS2 in GC tissues and cells, and analyze its significance in the prognosis of GC.

METHODS

Real-time quantitative PCR was used to detect the expression of HOXD-AS2 in 79 pairs of GC tissues and five cell lines. The pcHOXD-AS2 plasmid vector was constructed and transfected into SGC-7901 and SNU-1 GC cells. Matrigel Transwell and wound healing assays were used to confirm the effect of HOXD-AS2 on invasion and migration of GC cells. Cell counting kit-8 assay and flow cytometry were used to verify the effect of HOXD-AS2 on the proliferation, cell cycle, and apoptosis of GC cells. The relevant regulatory mechanism between HOXD-AS2 and HOXD8 and PI3K/Akt signaling pathway was verified by Western blot analysis.

RESULTS

The low expression of lncRNA HOXD-AS2 was associated with lymph node metastasis and tumor-node-metastasis stage in GC. In vitro functional experiments demonstrated that overexpression of HOXD-AS2 inhibited GC cell progression. Mechanistic studies revealed that HOXD-AS2 regulated the expression of its nearby gene HOXD8 and inhibited the activity of the PI3K/Akt signaling pathway.

CONCLUSION

These results indicate that downregulation of HOXD-AS2 significantly promotes the progression of GC cells by regulating HOXD8 expression and activating the PI3K/Akt signaling pathway. HOXD-AS2 may be a novel diagnostic biomarker and effective therapeutic target for GC.

LINC00861 inhibits the progression of cervical cancer&nbsp;cells by functioning as a ceRNA for miR‑513b‑5p and&nbsp;regulating the PTEN/AKT/mTOR signaling pathway

Long non‑coding RNAs (lncRNAs) have been discovered to serve important roles in a variety of types of cancer, including cervical cancer. The low expression of lncRNA long intergenic non‑protein coding RNA 861 (LINC00861) is related to poor prognosis in ovarian cancer. However, the effects and underlying mechanisms of LINC00861 in cervical cancer remain largely unknown. The present study aimed to examine the role of LINC00861 in the development and progression of ovarian cancer and its underlying mechanisms. The expression levels of LINC00861 and microRNA (miR)‑513b‑5p were analyzed using reverse transcription‑quantitative PCR analysis. Cell proliferation, migration and invasion were measured by using Cell Counting Kit‑8, colony formation, wound healing and Transwell assays, respectively. A luciferase assay was used to determine whether miR‑513b‑5p targeted LINC00861 and PTEN. The expression of protein was measured by using western blot assay. The results of the present study discovered that LINC00861 expression levels were significantly downregulated in cervical cancer tissues and CaSki and ME‑180 cell lines. Downregulated LINC00861 expression levels were identified to be associated with an advanced‑stage, lymph node metastasis and the poor survival of patients with cervical cancer. Gene Set Enrichment Analysis revealed that the PI3K/AKT/mTOR signaling pathway was significantly enriched in cervical tumors expressing low expression levels of LINC00861 compared with tumors expressing high levels of LINC00861. The overexpression of LINC00861 reduced cervical cancer cell proliferation, migration, invasion and epithelial‑mesenchymal transition (EMT) processes, upregulated PTEN protein expression levels and downregulated phosphorylated (p)‑AKT and p‑mTOR protein expression levels. The regulatory relationship between LINC00861, microRNA (miR)‑513b‑5p and PTEN was validated using a dual luciferase reporter gene assay. PTEN expression levels were significantly downregulated in the miR‑513b‑5p mimic group and significantly upregulated in the miR‑513b‑5p inhibitor group compared with the mimic NC and inhibitor NC in both cell lines. Furthermore, LINC00861 was suggested to serve as a competing endogenous RNA by sponging miR‑513b‑5p and consequently upregulating the expression levels of PTEN in cervical cancer cells. The expression of PTEN, the phosphorylation of Akt and mTOR and and the EMT phenotype were rescued following co‑transfection with LINC00861 and miR‑513b‑5p mimics. In conclusion, the findings of the present study indicated that the LINC00861/miR‑513b‑5p axis may inhibit the progression of cervical cancer cells through the PTEN/AKT/mTOR signaling pathway to suppress the EMT process.

The landscape of long non-coding RNAs in tumor stroma

AIMS

Long non-coding RNAs (lncRNAs) are associated with cancer development, while their relationship with the cancer-associated stromal components remains poorly understood. In this review, we performed a broad description of the functional landscape of stroma-associated lncRNAs in various cancers and their roles in regulating the tumor-stroma crosstalk.

MATERIALS AND METHODS

We carried out a systematic literature review of PubMed, Scopus, Medline, Bentham, and EMBASE (Elsevier) databases by using the keywords "LncRNAs in cancer," "LncRNAs in tumor stroma," "stroma," "cancer-associated stroma," "stroma in the tumor microenvironment," "tumor-stroma crosstalk," "drug resistance of stroma," and "stroma in immunosuppression" till July 2020. We collected the latest articles addressing the biological functions of stroma-associated lncRNAs in cancer.

KEY FINDINGS

These articles reported that dysregulated stroma-associated lncRNAs play significant roles in modulating the tumor microenvironment (TME) by the regulation of tumor-stroma crosstalk, epithelial to mesenchymal transition (EMT), endothelial to mesenchymal transition (EndMT), extracellular matrix (ECM) turnover, and tumor immunity.

SIGNIFICANCE

The tumor stroma is a substantial portion of the TME, and the dysregulation of tumor stroma-associated lncRNAs significantly contributes to cancer initiation, progression, angiogenesis, immune evasion, metastasis, and drug resistance. Thus, stroma-associated lncRNAs could be potentially useful targets for cancer therapy.

LncRNA NEAT1: Shedding light on mechanisms and opportunities in liver diseases

With advances in genome and transcriptome research technology, the function and mechanism of lncRNAs in physiological and pathological states have been gradually revealed. Nuclear Enriched Abundant Transcript 1 (NEAT1, a long non-coding RNA), a vital component of paraspeckles, plays an indispensable role in the formation and integrity of paraspeckles. Throughout the research history, NEAT1 is mostly aberrantly upregulated in various cancers, and high expression of NEAT1 often contributes to poor prognosis of patients. Notably, the role and mechanism of NEAT1 in liver diseases have been increasingly reported. NEAT1 accelerates the progression of non-alcoholic fatty liver disease (NAFLD), liver fibrosis and hepatocellular carcinoma, while exerting a protective role in the pathogenesis of acute-on-chronic liver failure by inhibiting the inflammatory response. In this review, we will elaborate on relevant studies on the different casting of NEAT1 in liver diseases, especially focusing on its regulatory mechanisms and new opportunities for alcoholic liver disease.

Inflammation-Induced Long Intergenic Noncoding RNA (LINC00665) Increases Malignancy Through Activating the Double-Stranded RNA-Activated Protein Kinase/Nuclear Factor Kappa B Pathway in Hepatocellular Carcinoma

BACKGROUND AND AIMS

The nuclear factor kappa B (NF-κB) signaling pathway is important for linking inflammation and tumorigenesis. Here, we characterized an NF-κB signaling activation-induced long intergenic noncoding (LINC) RNA in hepatocellular carcinoma (HCC), LINC00665, that contributes to the enhanced cell proliferation of HCC cells both in vitro and in vivo.

APPROACH AND RESULTS

LINC00665 physically interacts with the double-stranded RNA (dsRNA)-activated protein kinase (PKR), enhances its activation, and maintains its protein stability by blocking ubiquitin/proteasome-dependent degradation, resulting in a positive feedback regulation of NF-κB signaling in HCC cells. Notably, patients with HCC and higher LINC00665 have poorer outcomes in the clinic.

CONCLUSIONS

Our findings indicate that LINC00665 is involved in the NF-κB signaling activation in HCC cells and that the inflammatory LINC00665/PKR/NF-κB loop plays important oncogenic roles in hepatic cancer progression and may be a potential therapeutic target.

Long noncoding RNA lncGALM increases risk of liver metastasis in gallbladder cancer through facilitating N-cadherin and IL-1β-dependent liver arrest and tumor extravasation

BACKGROUND

Long noncoding RNAs (lncRNA) represent significant factors of the mammalian transcriptome that mediates varied biological and pathological processes. The liver is the most common site for gallbladder cancer (GBC) distant metastasis and contributes to the majority of GBC-related death. How lncRNA affects GBC metastasis is not completely understood.

RESULTS

A novel lncRNA termed lncGALM (lncRNA in GBC associated with liver metastasis) was discovered to be highly expressed in cancer patients and xenografted tumors with liver metastasis. Elevated lncGALM in GBC patients also correlated to decreased survival. Invasion and migration of GBC cells were enhanced through lncGALM, both in vitro and in vivo. lncGALM functioned as sponges by competitively binding to and inactivating miR-200 family members, which increase epithelial-mesenchymal transition-associated transcription factor ZEB1 and ZEB2, leading to a fibroblastic phenotype and increased expression of N-cadherin. In addition, lncGALM bound to IL-1β mRNA and stabilized the IL-1β gene that mediates liver sinusoidal endothelial cell (LSECs) apoptosis. lncGALM-expressing LiM2-NOZ cells acquired a strong ability to migrate and adhere to LSECs, promoting LSECs apoptosis and therefore facilitating tumor cell extravasation and dissemination.

CONCLUSIONS

lncGALM promotes GBC liver metastasis by facilitating GBC cell migration, invasion, liver arrest, and extravasation via the invasion-metastasis cascade. Targeting lncGALM may be protective against the development of liver metastasis in GBC patients.

Functional long non-coding RNAs in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a prevalent human malignancy with high morbidity worldwide. Hepatocarcinogenesis is a complex multistep process, and its underlying molecular mechanisms remain largely unknown. Recently, long non-coding RNAs (lncRNAs), a class of newly discovered molecules, have been revealed as essential regulators in the development of HCC. HCC-associated lncRNAs affect multiple malignant phenotypes by modulating gene expression or protein activity. Moreover, the dysregulation of lncRNAs in the liver is also associated with diseases predisposing to HCC, such as chronic viral infection, nonalcoholic steatohepatitis, and liver fibrosis/cirrhosis. A deeper understanding of the lncRNA regulatory network in the multistep processes of HCC development will provide new insights into the diagnosis and treatment of HCC. In this review, we introduce the biogenesis and function of lncRNAs and summarize recent knowledge on how lncRNAs regulate the malignant hallmarks of HCC, such as uncontrolled cell proliferation, resistance to cell death, metabolic reprogramming, immune escape, angiogenesis, and metastasis. We also review emerging insights into the role of lncRNAs in HCC-associated liver diseases. Finally, we discuss the potential applications of lncRNAs as early diagnostic biomarkers and therapeutic targets.

LncRNA TSLNC8 synergizes with EGFR inhibitor osimertinib to inhibit lung cancer tumorigenesis by blocking the EGFR-STAT3 pathway

The roles of lncRNA TSLNC8 and its synergetic effects with osimertinib remain unknown in lung cancer. qRT-PCR or western blotting was performed to determine the expression levels of TSLNC8, EGFR and STAT3. Colony formation and MTT assays were used to evaluate cell proliferation. Transwell and wound healing assays were performed to assess migration and invasion abilities. Flow cytometry with Annexin V/PI staining was used to detect changes in cell apoptosis. Nude mice subcutaneous tumor model was constructed and used for validating the effects of TSLNC8 and osimertinib in vivo. Expression of TSLNC8 was down-regulated in clinical lung cancer tissues and cell lines. TSLNC8 overexpression or osimertinib administration led to promotion of apoptosis and inhibition of cell proliferation, migration and invasion, as well as deactivation of the EGFR-STAT3 pathway, whereas TSLNC8 knockdown had opposite effects. Moreover, the above effects of osimertinib were remarkably enhanced by TSLNC8 overexpression and inhibited by TSLNC8 knockdown, respectively. Meanwhile, the effects of TSLNC8 overexpression were reversed by STAT3 activation or EGFR overexpression. In the animal model, combination of TSLNC8 overexpression and osimertinib administration resulted in efficient suppression of tumor growth. In this study, we revealed a TSLNC8-EGFR-STAT3 signaling axis in lung cancer, and TSLNC8 overexpression significantly enhanced the anti-tumor effects of osimertinib via inhibiting EGFR-STAT3 signaling.

Genome-Wide Analysis of the FOXA1 Transcriptional Network Identifies Novel Protein-Coding and Long Noncoding RNA Targets in Colorectal Cancer Cells

Differentiation status of tumors is correlated with metastatic potential and malignancy. FOXA1 (forkhead box A1) is a transcription factor known to regulate differentiation in certain tissues. Here, we investigate FOXA1 function in human colorectal cancer (CRC). We found that FOXA1 is robustly expressed in the normal human colon but significantly downregulated in colon adenocarcinoma. Applying FOXA1 chromatin immunoprecipitation coupled with deep sequencing and transcriptome analysis upon FOXA1 knockdown in well-differentiated CRC cells and FOXA1 overexpression in poorly differentiated CRC cells, we identified novel protein-coding and lncRNA genes regulated by FOXA1. Among the numerous novel FOXA1 targets we identified, we focused on CEACAM5, a tumor marker and facilitator of cell adhesion. We show that FOXA1 binds to a distal enhancer downstream of CEACAM5 and strongly activates its expression. Consistent with these data, we show that FOXA1 inhibits anoikis in CRC cells. Collectively, our results uncover novel protein-coding and noncoding targets of FOXA1 and suggest a vital role of FOXA1 in enhancing CEACAM5 expression and anoikis resistance in CRC cells.

LncRNA GATA6-AS1 Inhibits the Progression of Non-Small Cell Lung Cancer via Repressing microRNA-543 to Up-Regulating RKIP

Background

Much evidence unveils the significance of long non-coding RNAs (lncRNAs) in diverse cancers. This study was designed to clarify the function and mechanism of lncRNA GATA6 antisense RNA 1 (GATA6-AS1) in the progression of non-small cell lung cancer (NSCLC).

Methods

GATA6-AS1, miR-543 and Raf kinase inhibitor protein (RKIP) mRNA expressions were detected by qRT-PCR. Chi-square test was adopted to analyze the relationship between GATA6-AS1 expression and the clinicopathological parameters of NSCLC patients. NSCLC cells H1299 and H460 cells were used as overexpression or knockdown models, respectively, and cell proliferation and metastasis were determined by CCK-8 and Transwell assays. RKIP, E-cadherin, N-cadherin, STAT3, p-STAT3 expressions in NSCLC cells were detected by Western blot. The targeting relationship between GATA6-AS1 and miR-543 was confirmed by dual-luciferase reporter assay.

Results

GATA6-AS1 was significantly lowly expressed in NSCLC tissues and cell lines, and its low expression level was significantly correlated with larger tumor size and positive lymph node metastasis. GATA6-AS1 overexpression inhibited the proliferation, migration, invasion and epithelial–mesenchymal transition of NSCLC cells, while GATA6-AS1 knockdown caused the opposite effects. Mechanistically, it was confirmed that GATA6-AS1 impeded NSCLC cell proliferation and metastasis by adsorbing miR-543 and up-regulating the expression of RKIP.

Conclusions

As a tumor suppressor, GATA6-AS1 participates in suppressing the progression of NSCLC by modulating the miR-543/RKIP axis.

Interaction of BACH2 with FUS promotes malignant progression of glioma cells via the TSLNC8-miR-10b-5p-WWC3 pathway

Glioma, a common malignant tumour of the human central nervous system, has poor prognosis and limited treatment options. Dissecting the biological mechanisms underlying glioma pathogenesis can facilitate the development of better therapies. Here, we investigated the endogenous expression of BTB and CNC homolog 2 (BACH2), fused in sarcoma (FUS), TSLNC8 and microRNA (miR)‐10b‐5p in glioma cells and tissues. We studied the interaction between BACH2 and FUS and its contribution to glioma progression. We demonstrated that the interaction between BACH2 and FUS promoted glioma progression via transcriptional inhibition of TSLNC8. Overexpression of TSLNC8 restrained glioma progression by suppressing miR‐10b‐5p. Binding of TSLNC8 to miR‐10b‐5p attenuated the suppression of WWC family member 3 (WWC3) by miR‐10b‐5p and activated the Hippo signalling pathway. Growth of subcutaneous xenografts could be inhibited by knockdown of BACH2 or FUS, by overexpressing TSLNC8 or a combination of the three, also leading to a prolonged survival in nude mice. Our results indicate that the BACH2 and FUS/TSLNC8/miR‐10b‐5p/WWC3 axis is responsible for glioma development and could serve as a potential target for the development of new glioma therapies.

Long noncoding RNA TSLNC8 enhances pancreatic cancer aggressiveness by regulating CTNNB1 expression via association with HuR

Pancreatic cancer (PC) is one of the most lethal malignancies worldwide. Tumor suppressor long noncoding RNA on chromosome 8p12 (TSLNC8) is a newly identified long noncoding RNA (lncRNA) and play an important role in human cancers. However, the function and molecular mechanism of TSLNC8 in PC progression remain to be elucidated. Our results showed a significant increase of TSLNC8 expression in PC tissues and cell lines. Upregulation of TSLNC8 expression in PC tissues was closely correlated with TNM stage, distant and lymph node metastasis, and poor prognosis of PC patients. Functional experiments demonstrated that TSLNC8 promoted PC cells proliferation and invasion in vitro, and enhanced PC growth and metastasis in vivo. Mechanistically, TSLNC8 associated with HuR, promoted the binding of HuR with CTNNB1 mRNA and increased the stability of CTNNB1 mRNA, thus activating WNT/β-catenin signaling pathway. Taken together, our present study revealed that oncogenic lncRNA TSLNC8 positively regulate PC growth and metastasis via HuR-mediated mRNA stability of CTNNB1, extending the understanding of PC pathogenesis regulated by lncRNAs.

Emerging roles and potential clinical applications of noncoding RNAs in hepatocellular carcinoma

Hepatocellular carcinoma(HCC) is one of the most common forms of cancer, and accounts for a high proportion of cancer-associated deaths. Growing evidences have demonstrated that non- protein-coding regions of the genome could give rise to transcripts, termed noncoding RNA (ncRNA), that form novel functional layers of the cellular activity. ncRNAs are implicated in different molecular mechanisms and functions at transcriptional, translational and post-translational levels. An increasing number of studies have demonstrated a complex array of molecular and cellular functions of ncRNAs in different stages of the HCC tumorigenesis, either in an oncogenic or tumor-suppressive manner. As a result, several pre-clinical studies have highlighted the great potentials of ncRNAs as novel biomarkers for cancer diagnosis or therapeutics in targeting HCC progression. In this review, we briefly described the characteristics of several representative ncRNAs and summarized the latest findings of their roles and mechanisms in the development of HCC, in order to better understand the cancer biology and their potential clinical applications in this malignancy.

Silencing of LncRNA C1RL-AS1 Suppresses the Malignant Phenotype in Gastric Cancer Cells via the AKT/β-Catenin/c-Myc Pathway

Purpose: Numerous studies have shown that lncRNAs play vital roles in the development and progression of cancer. However, investigations of lncRNAs in gastric cancer are limited and need to be further pursued. Materials and Methods: According to RNA-seq results of gastric cancer (GC) tissues, we identified a novel lncRNA, C1RL-AS1. qRT-PCR was used to detect the expression level of C1RL-AS1 in paired GC and normal tissues. Nuclear/cytoplasmic fractionation was applied to evaluate the distribution of C1RL-AS1 in GC cells. For functional evaluation, CCK-8, colony formation, transwell, and apoptosis assays were used to determine the oncogenic role of C1RL-AS1. Results: C1RL-AS1 was upregulated in GC tissues, and high expression levels of C1RL-AS1 were associated with poor prognosis. Further in vitro functional assays revealed that silencing C1RL-AS1 attenuated the proliferation rate and migration ability and enhanced the apoptotic rate and the senescence of GC cells. The subsequent underlying mechanistic investigation revealed that Wnt/β-catenin was involved in C1RL-AS1-mediated signaling. Rescue experiments suggested that C1RL-AS1 probably promoted the malignant phenotype via the AKT/β-catenin pathway by downregulating c-Myc. Conclusions: C1RL-AS1 probably exerts its biological function by mediating the AKT/β-catenin/c-Myc pathway, indicating a novel therapeutic target in GC.

Therapy of Primary Liver Cancer

Primary liver cancer (PLC) is a fatal disease that affects millions of lives worldwide. PLC is the leading cause of cancer-related deaths and the incidence rate is predicted to rise in the coming decades. PLC can be categorized into three major histological subtypes: hepatocellular carcinoma (HCC), intrahepatic cholangiocarcinoma (ICC), and combined HCC-ICC. These subtypes are distinct with respect to epidemiology, clinicopathological features, genetic alterations, and clinical managements, which are thoroughly summarized in this review. The state of treatment strategies for each subtype, including the currently approved drugs and the potential novel therapies, are also discussed.

A nuclear lncRNA Linc00839 as a Myc target to promote breast cancer chemoresistance via PI3K/AKT signaling pathway

Chemoresistance has become a leading cause of mortality in breast cancer patients and is one of the major obstacles for improving the clinical outcome. Long noncoding RNAs play important roles in breast cancer tumorigenesis and chemoresistance. However, the involvement and regulation of lncRNAs in breast cancer chemoresistance are not completely understood. Here, we reported that Linc00839 was localized in the nucleus and upregulated in chemoresistant breast cancer cells and tissues, and high level of Linc00839 was associated with a poor prognosis. Knockdown of Linc00839 significantly suppressed proliferation, invasion, and migration, sensitized cells to paclitaxel in vitro and inhibited transplant tumor development in vivo. Mechanistically, we found that Myc could directly bind to the promoter region of Linc00839 and activate its transcription. Furthermore, Linc00839 overexpression increased the expression of Myc and the RNA‐binding protein Lin28B and activated the PI3K/AKT signaling pathway. We also discovered that Lin28B positively interacted with Linc00839 and was upregulated in breast cancer tissues. Taken together, for the first time, we showed that Linc00839 was activated by Myc and promoted proliferation and chemoresistance in breast cancer through binding with Lin28B. These findings provide new insight into the regulatory mechanism of Linc00839 and propose a Myc/Linc00839/Lin28B feedback loop that could be used as a novel therapeutic target for breast cancer.

NLRC3 silencing accelerates the invasion of hepatocellular carcinoma cell via IL-6/JAK2/STAT3 pathway activation

Nucleotide-binding domain, leucine-rich repeat family with a caspase activation and recruitment domain 3 (NLRC3) participates in both immunity and cancer. The aim of this study was to determine the role of NLRC3 in human hepatocellular carcinoma (HCC) and the underlying mechanisms. We collected human liver tissues from nonalcoholic steatohepatitis (NASH), HCC, and adjacent normal tissues to characterize the pattern of NLRC3 expression by real-time quantitative polymerase chain reaction and immunohistochemistry. Then, we used the HCC cell line, HuH-7, transfected with small interfering RNA to silence the NLRC3 expression. 5-Ethynyl-2'-deoxyuridine assay, scratch assay, and transwell invasion assay were used for assessing proliferation, migration, and invasion, respectively. Flow cytometry and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay were conducted to assess cell apoptosis. The expression of NLRC3 was reduced in human HCC tissues, compared with normal liver and nonalcoholic steatohepatitis tissues. After knocking down of NLRC3, the proliferation, migration, and invasion were increased in HuH-7 cells. And flow cytometry and TUNEL assay showed that HuH-7 cell apoptosis was suppressed after NLRC3 knockdown. As for the underlying mechanisms, knockdown of NLRC3 in HuH-7 cells was associated with the activation of Janus kinase 2/signal transducers and activators of transcription 3 (JAK2/STAT3) pathway under interleukin-6 (IL-6) stimulation. NLRC3 expression was downregulated in human HCC tissues. NLRC3 silencing in HuH-7 cells can promote the proliferation, migration, and invasion of hepatocellular carcinoma cells. JAK2/STAT3 pathway activation induced by IL-6 may be the underlying mechanism for HCC when NLRC3 expression is silenced. And the invasion of HuH-7 cells was partially suppressed by the STAT3 specific inhibitor (cryptotanshinone). Therefore, NLRC3 may play a significant role in HCC and might be a therapeutic target for the treatment of HCC.

Lnc-M2 controls M2 macrophage differentiation via the PKA/CREB pathway

Long noncoding RNAs (lncRNAs) play an indispensable role in the process of M1 macrophage via regulating the development of macrophages and their responses to bacterial pathogens and viral infections. However, there are few studies on the lncRNA-mediated functions and regulatory mechanisms of M2 macrophage polarization. In this study, we found a number of differentially expressed lncRNAs between human monocyte derived M0 and M2 macrophages according to array analysis and quantitative polymerase chain reaction (qPCR) validation. The lncRNA RP11-389C8.2 (we named lnc-M2 in this study) was observed to be highly expressed in M2 macrophages. In Situ Localization and Quantification Analysis showed that lnc-M2 was expressed in the nucleus and cytosolic compartments of M2 macrophages. Notably, lnc-M2 knockdown enhanced the phagocytic ability of M2 macrophages. Ulteriorly, the results of RNA-Protein interaction experiments indicated that protein kinase A (PKA) was a lnc-M2 associated RNA-binding protein (RBP). Western blot showed that phosphorylated cAMP response element binding protein (p-CREB), a well-known key downstream transcription factor of PKA, was lowly phosphorylated in lnc-M2-silencing M2 macrophages. Furthermore, we found that transcriptional factor Signal Transducer And Activator Of Transcription 3 (STAT3) promoted lnc-M2 transcription along with the up-regulation of epigenetic histone modification markers at the lnc-M2 promoter locus, indicating that STAT3 activated lnc-M2 and eventually facilitated the process of M2 macrophage differentiation via the PKA/CREB pathway. Collectively, our date provide evidence that the transcription factor STAT3 can promote the transcription of lnc-M2 and facilitated the process of M2 macrophage differentiation via the PKA/CREB pathway. This study highlights a novel mechanism underlying the M2 macrophage differentiation.

LINC01419 promotes cell proliferation and metastasis in hepatocellular carcinoma by enhancing NDRG1 promoter activity

PURPOSE

Emerging evidence indicates that dysfunction of long non-coding RNAs (lncRNAs) plays an essential role in the initiation and progression of hepatocellular carcinoma (HCC). In this study we investigated the potential roles and molecular mechanisms involving LINC01419 in HCC.

METHODS

The expression of LINC01419 in 40 pairs of HCC/normal tissues and 6 HCC cell lines was detected by qRT-PCR. MTS, EdU, colony formation, scratch wound-healing and transwell assays were performed to assess the role of LINC01419 in HCC cell (SMMC7721 and SK-Hep1) proliferation, migration and invasion in vitro. Artificial modulation of LINC01419 (up- and downregulation) was performed to explore the role of LINC01419 in tumor growth and metastasis in vivo. Interaction of LINC01419 with NDRG1 was assessed using qRT-PCR, RNA sequencing, Western blotting and immunohistochemistry. Physical interaction of LINC01419 with the NDRG1 promoter was assessed using a dual-luciferase reporter assay.

RESULTS

We observed LINC01419 overexpression in primary HCC tissues and HCC cell lines and that this overexpression positively correlated with large tumor size, increased vascular invasion and advanced TNM stage in 40 HCC patients. Exogenous LINC01419 expression significantly promoted HCC cell proliferation, migration and invasion in vitro, as well as tumorigenesis and metastasis in vivo. Conversely, we found that LINC01419 expression knockdown elicited opposite effects. Mechanistic investigations revealed that LINC01419 exerted its biological effects by regulating NDRG1. A dual-luciferase reporter assay revealed that LINC01419 interacts with a specific region within the NDRG1 promoter, resulting in its activation.

CONCLUSIONS

From our data we conclude that LINC01419 acts clinically, functionally and mechanistically oncogenic in HCC. LINC01419 may, therefore, serve as a promising prognostic indicator and therapeutic target for HCC.

A hMTR4-PDIA3P1-miR-125/124-TRAF6 Regulatory Axis and Its Function in NF kappa B Signaling and Chemoresistance

BACKGROUND AND AIMS

DNA damage-induced NF-κB activation is a major obstacle to effective antitumour chemotherapy. Long noncoding RNAs (lncRNAs) that regulate chemoresistance of cancer cells remain largely unknown. This study aimed to characterize the lncRNAs that may affect chemotherapy sensitivity.

APPROACH AND RESULTS

We found that lncRNA PDIA3P1 (protein disulfide isomerase family A member 3 pseudogene 1) was up-regulated in multiple cancer types and following treatment with DNA-damaging chemotherapeutic agents, like doxorubicin (Dox). Higher PDIA3P1 level was associated with poorer recurrence-free survival of human hepatocellular carcinoma (HCC). Both gain-of-function and loss-of-function studies revealed that PDIA3P1 protected cancer cells from Dox-induced apoptosis and allowed tumor xenografts to grow faster and to be more resistant to Dox treatment. Mechanistically, miR-125a/b and miR-124 suppressed the expression of tumor necrosis factor receptor-associated factor 6 (TRAF6), but PDIA3P1 bound to miR-125a/b/miR-124 and relieved their repression on TRAF6, leading to activation of the nuclear factor kappa B (NF-κB) pathway. Consistently, the effect of PDIA3P1 inhibition in promoting Dox-triggered apoptosis was antagonized by silencing the inhibitor of κBα (IκBα) or overexpressing TRAF6. Administration of BAY 11-7085, an NF-κB inhibitor attenuated PDIA3P1-induced resistance to Dox treatment in mouse xenografts. Moreover, up-regulation of PDIA3P1 was significantly correlated with elevation of TRAF6, phosphorylated p65, or NF-κB downstream anti-apoptosis genes in human HCC tissues. These data indicate that enhanced PDIA3P1 expression may confer chemoresistance by acting as a microRNA sponge to increase TRAF6 expression and augment NF-κB signaling. Subsequent investigations into the mechanisms of PDIA3P1 up-regulation revealed that human homologue of mRNA transport mutant 4 (hMTR4), which promotes RNA degradation, could bind to PDIA3P1, and this interaction was disrupted by Dox treatment. Overexpression of hMTR4 attenuated Dox-induced elevation of PDIA3P1, whereas silencing hMTR4 increased PDIA3P1 level, suggesting that Dox may up-regulate PDIA3P1 by abrogating the hMTR4-mediated PDIA3P1 degradation.

CONCLUSION

There exists a hMTR4-PDIA3P1-miR-125/124-TRAF6 regulatory axis that regulates NF-κB signaling and chemoresistance, which may be exploited for anticancer therapy.

Construction and evaluation of a prognosis lncRNA model for hepatocellular carcinoma

Current studies indicate that long non-coding RNA (lncRNA) is often abnormally expressed in hepatocellular carcinoma (HCC). We intend to generate a multi-lncRNA signal to improve the prognosis of HCC. By analyzing 12 pairs of HCC and adjacent normal mucosal tissues, 3900 differentially expressed lncrnas were identified as candidate biomarkers for the prognosis of HCC. Then, the 12-lncrna signature was constructed using the LASSO Cox regression method and verified in the TCGA training dataset. Finally, we established a novel 12-lncrna signature that was significantly associated with overall survival (OS) in the training data set. With the use of 12-lncrna markers, patients in the training cohort were divided into high-risk and low-risk groups with significant OV differences (P < .0001). Similar results were consistent in the TCGA verification dataset (P = .046). Multivariate Cox model was used to analyze and construct the risk scores of selected key lncRNA and AJCC stages. The results showed that, compared with AJCC stages, lncRNA-based risk scores were another important factor affecting the OS of patients. We found that risk scores based on lncRNA have a stronger prediction ability than the AJCC stage alone on 4-year OS. For 4-year survival rates, prediction combined with the lncRNA risk score and AJCC stage, model effectiveness (sensitivity and specificity) has reached to 0.750. To further explore the biological processes involved in prognostic lncRNA, all HCC samples in TCGA are divided into two groups according to the median lncRNA risk score, and analyzed the gene enrichment of high expression genes and low expression genes in KEGG data using goana in limma. The results suggest that the genes associated with tumor pathways, such as PI3K-Akt and ECM-receptor interaction, are highly expressed in the high risk group.

LncRNA GOLGA2P10 is induced by PERK/ATF4/CHOP signaling and protects tumor cells from ER stress-induced apoptosis by regulating Bcl-2 family members

Elevated endoplasmic reticulum (ER) stress is frequently observed in cancers, whereas sustained ER stress may trigger apoptosis. How cancer cells escape from ER stress-induced apoptosis remain unclear. Here, we found that a pseudogene-derived lncRNA, Golgin A2 pseudogene 10 (GOLGA2P10), was frequently upregulated in HCC tissues and significantly elevated in hepatoma cells treated with ER stress inducers, such as tunicamycin and thapsigargin. Higher GOLGA2P10 level was correlated with shorter recurrence-free survival of HCC patients. Upon ER stress, CHOP directly bound to the promoter of GOLGA2P10 and induced its transcription via the PERK/ATF4/CHOP pathway. Interestingly, the ER stress inducer-stimulated apoptosis was promoted by silencing GOLGA2P10 but was antagonized by overexpressing GOLGA2P10. Both gain- and loss-of-function analyses disclosed that GOLGA2P10 increased BCL-xL protein level, promoted BAD phosphorylation, and conferred tumor cells with resistance to ER stress-induced apoptosis. Moreover, BCL-xL overexpression or BAD knockdown abrogated the apoptosis-promoting effect of GOLGA2P10 silencing. Consistently, the Ser75Ala mutation in BAD, which caused phosphorylation-resistance, further enhanced the promoting effect of BAD in tunicamycin-induced apoptosis. These results suggest that ER stress induces GOLGA2P10 transcription through the PERK/ATF4/CHOP pathway, and upregulation of GOLGA2P10 protects tumor cells from the cytotoxic effect of persistent ER stress in tumor microenvironment by regulating Bcl-2 family members, which highlight GOLGA2P10 as a potential target for anticancer therapy.