LncRNA RUNX1-IT1 which is downregulated by hypoxia-driven histone deacetylase 3 represses proliferation and cancer stem-like properties in hepatocellular carcinoma cells

Circ1811 suppresses gastric cancer progression by regulating the miR-632/DAPK1 axis

Compelling evidence has identified circRNAs as crucial regulators in initiation and progression of various cancers, including gastric cancer (GC). However, the function and regulatory mechanisms of circRNAs in GC remain largely unknown. In this study, attention is paid to a novel circular RNA circ1811, which exerts significant downregulated expression in GC tissues compared with adjacent non-cancerous tissues. The expression of circ1811 in GC tumor tissues is negatively correlated with the extent of lymphatic metastasis in GC patients. Overexpression of circ1811 inhibited GC cell proliferation, migration and invasion while promoting apoptosis, whereas knockdown of circ1811 led to the opposite effects. AGO2 RIP and dual luciferase reporter assays indicated that circ1811 directly sponges miR-632 to upregulate the expression of DAPK1. Collectively, circ1811 acts as a tumor-suppressor for GC progression by regulating the miR-632/DAPK1 axis. Our findings suggest the potential of circ1811 as ideal biomarker and therapeutic target for GC.

The regulation of hypoxia-related lncRNAs in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is still a public health disease with its high prevalence and morbidity. Short of early diagnosis biomarkers and effective therapy, the treatment of HCC patients hasn't achieved ideal effect. Hypoxia is a hallmark of HCC, which is mainly induced by imbalance of tumor cell proliferation and insufficient supply of oxygen. Recently, amounting evidence suggested lncRNAs, especially hypoxia-related lncRNAs play a pivotal role in regulating HCC. Hypoxia-related lncRNAs are involved in altering glucose metabolism, maintaining of cancer stem cell-like properties (CSCs), cell apotosis, proliferation and immune escape, which all contribute to the poor prognosis of HCC patients. The novel identified hypoxia-related lncRNAs could be the potential target or biomarkers of HCC, which are beneficial to the clinical treatment. Herein, we summarized currently reported hypoxia-related lncRNAs and their related mechanisms, providing potential application and future perspective of hypoxia-related lncRNAs as a potential therapeutic target.

YAP1-activated ZNF131 promotes hepatocellular carcinoma cell proliferation through transcriptional regulation of PAIP1

Zinc finger protein 131 (ZNF131), a member of BTB-ZF transcription factors, has been previously reported as an oncogene in several human cancers. However, the function and underlying mechanism of ZNF131 in hepatocellular carcinoma (HCC) are still unclear. In our study, the upregulated expression of ZNF131 mRNA was confirmed in HCC tissues by analyzing the TCGA and GEO datasets. The immunohistochemical staining data also revealed the overexpression of ZNF131 protein in HCC samples. High expression of ZNF131 predicted poor overall survival and disease-free survival in HCC patients. ZNF131 knockdown inhibited the proliferation and colony formation and led to G2/M phase arrest of HCC cells, while its overexpression promoted HCC cell proliferation, cell cycle progression and colony formation. Moreover, ZNF131 silencing repressed the growth of HCC cells in nude mice. Yes-associated protein 1 (YAP1) was recognized as an upstream regulator of ZNF131. Both YAP1 knockdown and inactivation reduced ZNF131 expression in HCC cells, and YAP1 overexpression enhanced ZNF131 level. Interestingly, we found that poly(A) binding protein interacting protein 1 (PAIP1) was a novel target of ZNF131. ZNF131 silencing downregulated while ZNF131 overexpression upregulated PAIP1 expression in HCC cells. The luciferase reporter assay demonstrated that ZNF131 regulated PAIP1 expression at the transcription level. Notably, we revealed that ZNF131 activated the AKT signaling by enhancing PAIP1 expression in HCC cells. AKT inhibitor markedly attenuated ZNF131-enhanced HCC cell proliferation. Restoring PAIP1 expression abrogated the inhibitory effects of ZNF131 knockdown on HCC cell proliferation and colony formation. To conclude, ZNF131 was highly expressed and acted as an oncogene in HCC. ZNF131, which was activated by YAP1, promoted HCC cell proliferation through transcriptional regulation of PAIP1.

WNT/β-catenin signaling in hepatocellular carcinoma: The aberrant activation, pathogenic roles, and therapeutic opportunities

Hepatocellular carcinoma (HCC) is a liver cancer, highly heterogeneous both at the histopathological and molecular levels. It arises from hepatocytes as the result of the accumulation of numerous genomic alterations in various signaling pathways, including canonical WNT/β-catenin, AKT/mTOR, MAPK pathways as well as signaling associated with telomere maintenance, p53/cell cycle regulation, epigenetic modifiers, and oxidative stress. The role of WNT/β-catenin signaling in liver homeostasis and regeneration is well established, whereas in development and progression of HCC is extensively studied. Herein, we review recent advances in our understanding of how WNT/β-catenin signaling facilitates the HCC development, acquisition of stemness features, metastasis, and resistance to treatment. We outline genetic and epigenetic alterations that lead to activated WNT/β-catenin signaling in HCC. We discuss the pivotal roles of CTNNB1 mutations, aberrantly expressed non-coding RNAs and complexity of crosstalk between WNT/β-catenin signaling and other signaling pathways as challenging or advantageous aspects of therapy development and molecular stratification of HCC patients for treatment.

PCDH8 is a novel prognostic biomarker in thyroid cancer and promotes cell proliferation and viability

Protocadherin 8 (PCDH8), a calcium-dependent transmembrane protein in the protocadherin family, regulates cell adhesion and signal transduction. While some studies have provided indirect evidence that PCDH8 has cancer-promoting properties, this association is controversial. In particular, its involvement in thyroid cancer (THCA) remains unclear. We aimed to elucidate the role of PCDH8 in THCA using bioinformatic analysis. Subsequently, the results were experimentally validated. The analysis conducted using the R programming language and online web tools explored PCDH8 expression levels, prognostic, and clinical implications, and its relationship with the tumor immune microenvironment in THCA. Furthermore, we examined the association between PCDH8 and co-expressed genes, highlighting their involvement in several biological processes relevant to THCA. The potential of PCDH8 as a therapeutic target for this pathology was also explored. Immunohistochemical (IHC) staining was performed on samples from 98 patients with THCA, and experimental validation was carried out. PCDH8 was significantly elevated in cancer tissues and associated with poor prognosis, several clinical factors, and immune cell and checkpoint abundance. Cox regression and survival analyses, together with Receiver Operating Curves (ROC) indicated that PCDH8 was an independent prognostic factor for THCA. Furthermore, PCDH8 impacts cell viability and proliferation, promoting tumorigenesis. Also, it influences tumor cell sensitivity to various drugs. Thus, PCDH8 might be a potential therapeutic target for THCA. IHC, cell culture, MTT, and colony formation experiments further confirmed our findings. This analysis provided insights into the potential carcinogenic role of PCDH8 in THCA, as it impacts cell viability and proliferation. Thus, PCDH8 might play an important role in its prognosis, immune infiltration, and diagnosis.

RUNX1-IT1 acts as a scaffold of STAT1 and NuRD complex to promote ROS-mediated NF-κB activation and ovarian cancer progression

Dysregulated expression of long-stranded non-coding RNAs is strongly associated with carcinogenesis. However, the precise mechanisms underlying their involvement in ovarian cancer pathogenesis remain poorly defined. Here, we found that lncRNA RUNX1-IT1 plays a crucial role in the progression of ovarian cancer. Patients with high RUNX1-IT1 expression had shorter survival and poorer outcomes. Notably, knockdown of RUNX1-IT1 suppressed the proliferation, migration and invasion of ovarian cancer cells in vitro, and reduced the formation of peritoneum metastasis in vivo. Mechanistically, RUNX1-IT1 bound to HDAC1, the core component of the NuRD complex, and STAT1, acting as a molecular scaffold of the STAT1 and NuRD complex to regulate intracellular reactive oxygen homeostasis by altering the histone modification status of downstream targets including GPX1. Consequently, RUNX1-IT1 activated NF-κB signaling and altered the biology of ovarian cancer cells. In conclusion, our findings demonstrate that RUNX1-IT1 promotes ovarian malignancy and suggest that targeting RUNX1-IT1 represents a promising therapeutic strategy for ovarian cancer treatment.

LncRNA RUNX1-IT1 is downregulated in gastric cancer and suppresses the maturation of miR-20a by binding to its precursor

BACKGROUND

RUNX1-IT1 has been characterized as a tumor suppressive long non-coding RNA (lncRNA) in several types of cancer but not gastric cancer (GC). This study aimed to explore the role of RUNX1-IT1 in GC.

METHODS

The expression of RUNX1-IT1, microRNA (miR)-20a precursor and mature miR-20a in GC and healthy tissues donated by GC patients (n=62) were measured by RT-qPCR. Correlation analysis was performed by linear regression. The expression of mature miR-20a and miR-20a precursor in cells with overexpression of RUNX1-IT1 was also determined by RT-qPCR. Cell invasion and migration were evaluated by Transwell assays.

RESULTS

RUNX1-IT1 was downregulated in GC. Across GC tissues, RUNX1-IT1 and mature miR-20a were inversely correlated. However, RUNX1-IT1 and miR-20a precursor were not closely correlated. RUNX1-IT1 and miR-20a precursor were predicted to interact with each other, and overexpression of RUNX1-IT1 in GC cells decreased the expression levels of mature miR-20a. Transwell assay showed that the enhancing effect of miR-20a on cell invasion and migration was reduced by overexpression of RUNX1-IT1.

CONCLUSIONS

RUNX1-IT1 may suppress the GC cell movement by inhibiting the maturation of miR-20a.

LncRNA FTO-IT1 promotes glycolysis and progression of hepatocellular carcinoma through modulating FTO-mediated N6-methyladenosine modification on GLUT1 and PKM2

BACKGROUND

Long non-coding RNAs (LncRNAs) have been extensively studied to play essential roles in tumor progression. However, more in-depth studies are waiting to be solved on how lncRNAs regulate the progression of hepatocellular carcinoma (HCC).

METHODS

Different expression levels of lncRNAs in HCC cells were compared by analysis of Gene Expression Omnibus and The Cancer Genome Atlas databases. The effects of lncRNA FTO Intronic Transcript 1 (FTO-IT1) on HCC cells were assessed by gain- and loss-of-function experiments. Colony formation assay, Edu assay, glucose uptake and lactic acid production assay were performed to evaluate the regulation of proliferation and glycolysis of HCC cells by FTO-IT1. The binding between protein interleukin enhancer binding factor 2/3 (ILF2/ILF3) and FTO-IT1 was determined by RNA pull-down, mass spectroscopy and RNA immunoprecipitation experiments. RNA stability assay, quantitative reverse transcription PCR and Western blot were employed to determine the regulatory mechanisms of FTO-IT1 on fat mass and obesity-associated (FTO). Methylated RNA immunoprecipitation assay was used to assessed the regulation of key enzymes of glycolysis by FTO. The role of FTO-IT1/FTO in vivo was confirmed via xenograft tumor model.

RESULTS

LncRNA FTO-IT1, an intronic region transcript of FTO gene, was highly expressed in HCC and associated with poor prognosis of patients with HCC. FTO-IT1 was related to proliferation and glycolysis of HCC cells, and contributed to the malignant progression of HCC by promoting glycolysis. Mechanistically, FTO-IT1 induced stabilization of FTO mRNA by recruiting ILF2/ILF3 protein complex to 3'UTR of FTO mRNA. As a demethylase for N6-methyladenosine (m6A), FTO decreased m6A modification on mRNAs of glycolysis associated genes including GLUT1, PKM2, and c-Myc which alleviated the YTH N6-methyladenosine RNA binding protein 2 (YTHDF2)-mediated mRNA degradation. Therefore, the upregulated expression of FTO-IT1 leaded to overexpression of GLUT1, PKM2, and c-Myc by which enhanced glycolysis of HCC. Meanwhile, it was found that c-Myc transcriptional regulated expression of FTO-IT1 by binding to its promoter area under hypo-glucose condition, forming a reciprocal loop between c-Myc and FTO-IT1.

CONCLUSIONS

This study identified an important role of the FTO-IT1/FTO axis mediated m6A modification of glycolytic genes contributed to glycolysis and tumorigenesis of HCC, and FTO-IT1 might be served as a new therapeutic target for HCC.

Multiple Roles of the RUNX Gene Family in Hepatocellular Carcinoma and Their Potential Clinical Implications

Hepatocellular carcinoma (HCC) is one of the most frequent cancers in humans, characterised by a high resistance to conventional chemotherapy, late diagnosis, and a high mortality rate. It is necessary to elucidate the molecular mechanisms involved in hepatocarcinogenesis to improve diagnosis and treatment outcomes. The Runt-related (RUNX) family of transcription factors (RUNX1, RUNX2, and RUNX3) participates in cardinal biological processes and plays paramount roles in the pathogenesis of numerous human malignancies. Their role is often controversial as they can act as oncogenes or tumour suppressors and depends on cellular context. Evidence shows that deregulated RUNX genes may be involved in hepatocarcinogenesis from the earliest to the latest stages. In this review, we summarise the topical evidence on the roles of RUNX gene family members in HCC. We discuss their possible application as non-invasive molecular markers for early diagnosis, prognosis, and development of novel treatment strategies in HCC patients.

FOXC2-AS1/FOXC2 axis mediates matrix stiffness-induced trans-differentiation of hepatic stellate cells into fibrosis-promoting myofibroblasts

Matrix stiffness is a central modulator of hepatic stellate cells (HSCs) activation and hepatic fibrogenesis. However, the long non-coding RNAs (lncRNAs)-regulated transcriptional factors linking matrix stiffness to alterations in HSCs phenotype are not completely understood. In this study, we investigated the effects of matrix stiffness on HSCs activation and its potential mechanism. Through analysis the RNA-seq data with human primary HSCs cultured on 0.4 kPa and 25.6 kPa hydrogel, we identified that forkhead box protein C2 (FOXC2) and its antisense lncRNA FXOC2-AS1 as the new mechanosensing transcriptional regulators that coordinate HSCs responses to the matrix stiffness, moreover, FOXC2 and FOXC2-AS1 expression were also elevated in human fibrosis and cirrhosis tissues. The matrix stiffness was sufficient to activate HSCs into myofibroblasts, resulting in nuclear accumulation of FOXC2. Disrupting FOXC2 and FOXC2-AS1 level abrogated stiffness-induced activation of HSCs. Further mechanistic studies displayed that stiffness-upregulated lncRNA FOXC2-AS1 had no influence on transcription of FOXC2. FOXC2-AS1 exerted its biological function through maintaining the RNA stability of FOXC2, and protecting FOXC2 mRNA from degradation by RNA exosome complex. Additionally, rescue assays confirmed that reintroduction of FOXC2 in FOXC2-AS1-depleted HSCs reversed the repression of FOXC2-AS1 knockdown on stiffness-induced HSCs activation. In AAV6-treated mice fibrotic models, targeting FOXC2 in vivo lead to a reduced degree of liver fibrosis. In sum, our study uncovers a reciprocal crosstalk between matrix stiffness and FOXC2-AS1/FOXC2 axis leading to modulation of HSCs mechanoactivation and liver fibrosis, and present AAV6 shRNA as an effective strategy that targets FOXC2 leading to the resolution of liver fibrosis.

HIF-1α-activated TMEM237 promotes hepatocellular carcinoma progression via the NPHP1/Pyk2/ERK pathway

BACKGROUND

Hypoxia-inducible factors (HIFs) are the most essential endogenous transcription factors in the hypoxic microenvironment and regulate multiple genes involved in the proliferation, migration, invasion, and EMT of hepatocellular carcinoma (HCC) cells. However, the regulatory mechanism of HIFs in driving HCC progression remains poorly understood.

METHODS

Gain- and loss-of-function experiments were carried out to investigate the role of TMEM237 in vitro and in vivo. The molecular mechanisms involved in HIF-1α-induced TMEM237 expression and TMEM237-mediated enhancement of HCC progression were confirmed by luciferase reporter, ChIP, IP-MS and Co-IP assays.

RESULTS

TMEM237 was identified as a novel hypoxia-responsive gene in HCC. HIF-1α directly bound to the promoter of TMEM237 to transactivate its expression. The overexpression of TMEM237 was frequently detected in HCC and associated with poor clinical outcomes in patients. TMEM237 facilitated the proliferation, migration, invasion, and EMT of HCC cells and promoted tumor growth and metastasis in mice. TMEM237 interacted with NPHP1 and strengthened the interaction between NPHP1 and Pyk2 to trigger the phosphorylation of Pyk2 and ERK1/2, thereby contributing to HCC progression. The TMEM237/NPHP1 axis mediates hypoxia-induced activation of the Pyk2/ERK1/2 pathway in HCC cells.

CONCLUSIONS

Our study demonstrated that HIF-1α-activated TMEM237 interacted with NPHP1 to activate the Pyk2/ERK pathway, thereby promoting HCC progression.

RUNX1-IT1 favors breast cancer carcinogenesis through regulation of IGF2BP1/GPX4 axis

Breast cancer is the most common malignancy among women and the leading cause of cancer deaths, with complicated pathogenesis that is largely unknown. In this study, we identified a novel long non-coding RNA (lncRNA) as a critical driver of breast cancer tumorigenesis. RUNX1 intronic transcript 1 (RUNX1-IT1) was notably overexpressed in human breast cancer tissues, and knockdown of RUNX1-IT1 inhibited breast cancer cell viability and invasion, as well as tumor growth in orthotopic transplantation model. Further, RUNX1-IT1 repressed ferroptosis, a novel iron-dependent form of regulated cell death, via increasing glutathione peroxidase 4 (GPX4) expression. Specifically, RUNX1-IT1 directly bound to N6-methyladenosine m⁶A reader IGF2BP1 and promoted the formation of (insulin like growth factor 2 mRNA binding protein 1) IGF2BP1 liquid-liquid phase separation (LLPS) biomolecular condensates, resulting in more IGF2BP1 occupation on GPX4 mRNA, increasing GPX4 mRNA stability. Moreover, high RUNX1-IT1 was linked to poor prognosis, and a strong positive correlation between RUNX1-IT1 and GPX4 was observed in clinical breast cancer tissues. Taken together, our data reveal that RUNX1-IT1 promotes breast cancer carcinogenesis through blocking ferroptosis via elevating GPX4, targeting of the previously unappreciated regulatory axis of RUNX1-IT1/IGF2BP1/GPX4 may be a promising treatment for patient with breast cancer.

Hypoxia-induced lncRNA MRVI1-AS1 accelerates hepatocellular carcinoma progression by recruiting RNA-binding protein CELF2 to stabilize SKA1 mRNA

BACKGROUND

Long non-coding RNAs (lncRNAs) perform a vital role during the progression of hepatocellular carcinoma (HCC). Here, we aimed to identify a novel lncRNA involved in HCC development and elucidate the underlying molecular mechanism.

METHODS

The RT-qPCR and TCGA dataset analysis were applied to explore the expressions of MRVI1-AS1 in HCC tissues and cell lines. Statistical analysis was applied to analyze the clinical significance of MRVI1-AS1 in HCC. The functions of MRVI1-AS1 in HCC cells metastasis and growth were explored by transwell assays, wound healing assay, MTT assay, EdU assay, the intravenous transplantation tumor model, and the subcutaneous xenograft tumor model. Microarray mRNA expression analysis, dual luciferase assays, and actinomycin D treatment were used to explore the downstream target of MRVI1-AS1 in HCC cells. RIP assay was applied to assess the direct interactions between CELF2 and MRVI1-AS1 or SKA1 mRNA. Rescue experiments were employed to validate the functional effects of MRVI1-AS1, CELF2, and SKA1 on HCC cells.

RESULTS

MRVI1-AS1 was found to be dramatically upregulated in HCC and the expression was strongly linked to tumor size, venous infiltration, TNM stage, as well as HCC patients' outcome. Cytological experiments and animal experiments showed that MRVI1-AS1 promoted HCC cells metastasis and growth. Furthermore, SKA1 was identified as the downstream targeted mRNA of MRVI1-AS1 in HCC cells, and MRVI1-AS1 increased SKA1 expression by recruiting CELF2 protein to stabilize SKA1 mRNA. In addition, we found that MRVI1-AS1 expression was stimulated by hypoxia through a HIF-1-dependent manner, which meant that MRVI1-AS was a direct downstream target gene of HIF-1 in HCC.

CONCLUSION

In a word, our findings elucidated that hypoxia-induced MRVI1-AS1 promotes metastasis and growth of HCC cells via recruiting CELF2 protein to stabilize SKA1 mRNA, pointing to MRVI1-AS1 as a promising clinical application target for HCC therapy.

Molecular regulation of hypoxia through the lenses of noncoding RNAs and epitranscriptome

Cells maintain homeostasis in response to environmental stress through specific cell stress responses. Hypoxic stress, well known to be associated with diverse solid tumors, is one of the main reasons for cancer-related mortality. Although cells can balance themselves well during hypoxic stress, the underlying molecular mechanisms are not well understood. The enhanced appreciation of diverse roles played by noncoding transcriptome and epigenome in recent years has brought to light the involvement of noncoding RNAs and epigenetic modifiers in hypoxic regulation. The emergence of techniques like deep sequencing has facilitated the identification of large numbers of long noncoding RNAs (lncRNAs) that are differentially regulated in various cancers. Similarly, proteomic studies have identified diverse epigenetic modifiers such as HATs, HDACs, DNMTs, polycomb groups of proteins, and their possible roles in the regulation of hypoxia. The crosstalk between lncRNAs and epigenetic modifiers play a pivotal role in hypoxia-induced cancer initiation and progression. Besides the lncRNAs, several other noncoding RNAs like circular RNAs, miRNAs, and so forth are also expressed during hypoxic conditions. Hypoxia has a profound effect on the expression of noncoding RNAs and epigenetic modifiers. Conversely, noncoding RNAs/epigenetic modifies can regulate the hypoxia signaling axis by modulating the stability of the hypoxia-inducible factors (HIFs). The focus of this review is to illustrate the molecular orchestration underlying hypoxia biology, especially in cancers, which can help in identifying promising therapeutic targets in hypoxia-induced cancers. This article is categorized under: RNA Turnover and Surveillance > Regulation of RNA Stability RNA in Disease and Development > RNA in Disease RNA Structure and Dynamics > RNA Structure, Dynamics and Chemistry.

Long Noncoding RNAs and Cancer Stem Cells: Dangerous Liaisons Managing Cancer

Decades of research have investigated the mechanisms that lead to the origin of cancer, striving to identify tumor-initiating cells. These cells, also known as cancer stem cells, are characterized by the ability to self-renew, to give rise to differentiated tumor populations, and on a larger scale, are deemed responsible not only for tumor initiation but also for recurrent tumors, often resistant to chemotherapy and radiotherapy. Long noncoding RNAs are RNA molecules longer than 200 nt, lacking the ability to code for proteins, with recognized roles as fine regulators of gene expression. They can exert these functions through a variety of mechanisms, acting at almost all steps of gene expression, from modulation of the epigenetic state of chromatin to modulation of protein stability. In all cases, lncRNAs do not work alone, but they always interact with other RNA molecules, either coding or non-coding, or with protein factors. In this review, we summarize the latest results obtained about the involvement of lncRNAs in the initiating cells of several types of tumors, and highlight the different mechanisms through which they work, while discussing how the modulation of a lncRNA can affect several aspects of tumor onset and progression.

Long non-coding RNAs (lncRNAs) in hepatocellular carcinoma progression: Biological functions and new therapeutic targets

Liver is an important organ in body that performs vital functions such as detoxification. Liver is susceptible to development of cancers, and hepatocellular carcinoma (HCC) is among them. 75-85% of liver cancer cases are related to HCC. Therefore, much attention has been directed towards understanding factors mediating HCC progression. LncRNAs are epigenetic factors with more than 200 nucleotides in length located in both nucleus and cytoplasm and they are promising candidates in cancer therapy. Directing studies towards understanding function of lncRNAs in HCC is of importance. LncRNAs regulate cell cycle progression and growth of HCC cells, and they can also induce/inhibit apoptosis in tumor cells. LncRNAs affect invasion and metastasis in HCC mainly by epithelial-mesenchymal transition (EMT) mechanism. Revealing the association between lncRNAs and downstream signaling pathways in HCC is discussed in the current manuscript. Infectious diseases can affect lncRNA expression in mediating HCC development and then, altered expression level of lncRNA is associated with drug resistance and radio-resistance. Biomarker application of lncRNAs and their role in prognosis and diagnosis of HCC are also discussed to pave the way for treatment of HCC patients.

MiR-195 connects lncRNA RUNX1-IT1 and cyclin D1 to regulate the proliferation of glioblastoma cells

AIMS

LncRNA RUNX1-IT1 has been characterized as a tumor suppressive lncRNA in several cancers, while its role in glioblastoma (GBM) is unknown. This study aimed to investigate the potential involvement of RUNX1-IT1 in GBM.

METHODS

Expression of RUNX1-IT1 in GBM tissues and paired non-tumor tissues was determined by RT-qPCR. The interaction between RUNX1-IT1 and miR-195 was analyzed by dual luciferase activity assay. Overexpression of RUNX1-IT1 and miR-195 was achieved in GBM cells to explore the interaction between them. The effects of RUNX1-IT1 and miR-195 overexpression on the expression of cyclin D1 were analyzed by RT-qPCR and Western blot. Cell proliferation was analyzed by CCK-8 assay.

RESULTS

RUNX1-IT1 was upregulated in GBM. RUNX1-IT1 and miR-195 interacted with each other, but failed to regulate the expression of each other. Overexpression of RUNX1-IT1 resulted in the upregulation of cyclin D1, and also reduced the effects of miR-195 overexpression on cyclin D1 expression. RUNX1-IT1 and cyclin overexpression increased cell proliferation, while miR-195 overexpression decreased cell proliferation. In addition, RUNX1-IT1 overexpression reduced the effects of miR-195 overexpression on cell proliferation.

CONCLUSIONS

RUNX1-IT1 may sponge miR-195 to upregulate cyclin D1, thereby increasing the proliferation of glioblastoma cells.

Wnt/β-Catenin Signaling as a Driver of Stemness and Metabolic Reprogramming in Hepatocellular Carcinoma

Simple Summary

Aberrant Wnt/β-catenin signaling has been reported to play crucial role in pathogenesis of hepatocellular carcinoma (HCC). In this review, we focus on the regulatory role of Wnt/β-catenin signaling in cancer stemness and metabolic reprogramming, which are two emerging hallmarks of cancer. Understanding the role of Wnt/β-catenin signaling in regulation of the above processes reveals novel therapeutic strategy against this deadly disease.

Abstract

Hepatocellular carcinoma (HCC) is a major cause of cancer death worldwide due to its high rates of tumor recurrence and metastasis. Aberrant Wnt/β-catenin signaling has been shown to play a significant role in HCC development, progression and clinical impact on tumor behavior. Accumulating evidence has revealed the critical involvement of Wnt/β-catenin signaling in driving cancer stemness and metabolic reprogramming, which are regarded as emerging cancer hallmarks. In this review, we summarize the regulatory mechanism of Wnt/β-catenin signaling and its role in HCC. Furthermore, we provide an update on the regulatory roles of Wnt/β-catenin signaling in metabolic reprogramming, cancer stemness and drug resistance in HCC. We also provide an update on preclinical and clinical studies targeting Wnt/β-catenin signaling alone or in combination with current therapies for effective cancer therapy. This review provides insights into the current opportunities and challenges of targeting this signaling pathway in HCC.

RUNX Family in Hypoxic Microenvironment and Angiogenesis in Cancers

The tumor microenvironment (TME) is broadly implicated in tumorigenesis, as tumor cells interact with surrounding cells to influence the development and progression of the tumor. Blood vessels are a major component of the TME and are attributed to the creation of a hypoxic microenvironment, which is a common feature of advanced cancers and inflamed premalignant tissues. Runt-related transcription factor (RUNX) proteins, a transcription factor family of developmental master regulators, are involved in vital cellular processes such as differentiation, proliferation, cell lineage specification, and apoptosis. Furthermore, the RUNX family is involved in the regulation of various oncogenic processes and signaling pathways as well as tumor suppressive functions, suggesting that the RUNX family plays a strategic role in tumorigenesis. In this review, we have discussed the relevant findings that describe the crosstalk of the RUNX family with the hypoxic TME and tumor angiogenesis or with their signaling molecules in cancer development and progression.

Hypoxia-induced LINC00674 facilitates hepatocellular carcinoma progression by activating the NOX1/mTOR signaling pathway

The hypoxic tumor microenvironment, a fundamental feature of solid tumors, drives hepatocellular carcinoma (HCC) progression through regulating the transcriptional activities of protein-coding and noncoding genes. However, long noncoding RNA (lncRNA)-mediated HCC progression in hypoxic microenvironment remains largely unknown yet. In this study, we found that LINC00674 was upregulated under hypoxic conditions in a HIF-1-dependent manner, and the occupancy of HIF-1 to HRE of LINC00674 gene promoter was essential for its transcription. In addition, LINC00674 level was increased in HCC cell lines and tissues. Clinically, statistical analysis showed that LINC00674 expression was significantly associated with tumor size, venous infiltration, tumor stage and poor prognosis of HCC. Functionally, loss-of-function assays revealed that LINC00674 knockdown inhibited the migration, proliferation and invasion of HCC cells. Furthermore, LINC00674 silencing prominently repressed the mTOR signaling pathway. LINC00674 overexpression-enhanced HCC cell proliferation, migration and invasion were markedly abolished by an mTOR inhibitor rapamycin. NADPH oxidase 1 (NOX1) was positively regulated by LINC00674 in HCC cells. NOX1 knockdown markedly reversed LINC00674-upregulated the p-mTOR level and HCC cells' malignant behaviors. Finally, we found that LINC00674 knockdown attenuated the growth of HCC cells in vivo. Our finding demonstrated that LINC00674 was a new HIF-1 target gene, and hypoxia-induced LINC00674 exerted a pro-proliferative and pro-metastatic role in HCC, possibly by activating the NOX1/mTOR signaling pathway. This study suggested LINC00674 as a promising therapeutic target for HCC.

Hypoxia-driven miR-1307-3p promotes hepatocellular carcinoma cell proliferation and invasion by modulating DAB2 interacting protein

Hypoxia is a common feature of the solid tumor microenvironment that is presented as poor clinical outcomes in multiple tumor types, including HCC. Hypoxia stabilizes HIF-1α/HIF-2α, which then moves into the nucleus and binds with HIF-1β to form a transcription complex, thereby promoting the transcription of target genes, including mRNAs, miRNAs and lncRNAs to exert their biological functions. Here, through a series of functional assay, including hypoxia culture, MTT, colony-formation, Transwell, qRT-PCR and western blot, we confirmed that miR-1307-3p, as a novel hypoxia-responsive factor, can be directly transcribed by HIF-1α rather than HIF-2α. Hypoxia-driven miR-1307-3p facilitated proliferation and invasion of HCC cells via repressing DAB2IP. Moreover, under hypoxia microenvironment, DAB2IP, as a direct target of miR-1307-3p, was down-regulated to activate AKT/mTOR signaling to further maintain the expression level of HIF-1α, thereby forming a feedback loop between HIF-1α/miR-1307-3p and DAB2IP. Targeting miR-1307-3p/DAB2IP axis also modulated tumor growth and metastasis in vivo. In summary, there exists a feedback loop between HIF-1α/miR-1307-3p and DAB2IP in HCC. Targeting a vicious feedback loop between HIF-1α/miR-1307-3p and DAB2IP may be a promising strategy to combat HCC.

Hypoxia-induced LncRNA DACT3-AS1 upregulates PKM2 to promote metastasis in hepatocellular carcinoma through the HDAC2/FOXA3 pathway

Growing evidence has revealed that hypoxia is involved in multiple stages of cancer development. However, there are limited reports on the effects of long noncoding RNAs (lncRNAs) on hepatocellular carcinoma (HCC) progression under hypoxia. The main purposes of this study were to analyze the effect of the novel lncRNA DACT3-AS1 on metastasis in HCC and to elucidate the related molecular mechanism. Bioinformatics tools were employed. RT–qPCR or western blot assays were conducted to detect RNA or protein expression. Clinical samples and in vivo assays were utilized to reveal the role of DACT3-AS1 in HCC. Other mechanism and functional analyses were specifically designed and performed as well. Based on the collected data, this study revealed that HIF-1α transcriptionally activates DACT3-AS1 expression under hypoxia. DACT3-AS1 was verified to promote metastasis in HCC. Mechanistically, DACT3-AS1 promotes the interaction between HDAC2 and FOXA3 to stimulate FOXA3 deacetylation, which consequently downregulates the FOXA3 protein. Furthermore, FOXA3 serves as a transcription factor that can bind to the PKM2 promoter region, thus hindering PKM2 expression. To summarize, this study uncovered that HIF-1α-induced DACT3-AS1 promotes metastasis in HCC and can upregulate PKM2 via the HDAC2/FOXA3 pathway in HCC cells.

Understanding the role of an RNA molecule involved in metastasis (spread) of liver cancer may suggest potential therapeutic targets. Hepatocarcinoma is a common primary liver cancer, and mortality remains high due to late diagnosis and the risk of metastasis. Scientists believe hypoxic (low oxygen) conditions in solid tumors may trigger metastasis by a mechanism involving long non-coding RNAs. Bin Li and co-workers at the Affiliated Hospital of Guilin Medical College, China, used patient tissue samples to examine the role of the long non-coding RNA molecule DACT3-AS1 in promoting hepatocarcinoma metastasis. Hypoxia triggers the overexpression of HIF-1α. This protein activated DACT3-AS1, which was then highly expressed in metastatic tissues. DACT3-AS1 interacted with a nearby gene and associated enzyme to promote cell migration and invasion, hinting at possible treatment options.

Long noncoding RNA SH3PXD2A-AS1 promotes NSCLC proliferation and accelerates cell cycle progression by interacting with DHX9

As the most commonly diagnosed lung cancer, non-small cell lung carcinoma (NSCLC) is regulated by many long noncoding RNAs (lncRNAs). In the present study, we found that SH3PXD2A-AS1 expression in NSCLC tissues was upregulated compared with that in normal lung tissues in The Cancer Genome Atlas (TCGA) database by using the GEPIA website. K-M analysis was performed to explore the effects of this molecule on the survival rate in NSCLC. The results demonstrated that SH3PXD2A-AS1 expression was increased in human NSCLC, and high SH3PXD2A-AS1 expression was correlated with poor overall survival. SH3PXD2A-AS1 promotes lung cancer cell proliferation and accelerates cell cycle progression in vitro. Animal studies validated that knockdown of SH3PXD2A-AS1 inhibits NSCLC cell proliferation in vivo. Mechanically, SH3PXD2A-AS1 interacted with DHX9 to enhance FOXM1 expression, promote tumour cell proliferation and accelerate cell cycle progression. Altogether, SH3PXD2A-AS1 promoted NSCLC growth by interacting with DHX9 to enhance FOXM1 expression. SH3PXD2A-AS1 may serve as a promising predictive biomarker for the diagnosis and prognosis of patients with NSCLC.

Roles of lncRNAs Mediating Wnt/β-Catenin Signaling in HCC

Hepatocellular carcinoma (HCC) is considered the second most deadly cancer worldwide. Due to the absence of early diagnostic markers and effective therapeutic approaches, distant metastasis and increasing recurrence rates are major difficulties in the clinical treatment of HCC. Further understanding of its pathogenesis has become an urgent goal in HCC research. Recently, abnormal expression of long noncoding RNAs (lncRNAs) was identified as a vital regulator involved in the initiation and development of HCC. Activation of the Wnt/β-catenin pathway has been reported to obviously impact cell proliferation, invasion, and migration of HCC. This article reviews specific interactions, significant mechanisms and molecules related to HCC initiation and progression to provide promising strategies for treatment.

lncRNA SNHG26 promoted the growth, metastasis, and cisplatin resistance of tongue squamous cell carcinoma through PGK1/Akt/mTOR signal pathway

Tongue squamous cell carcinoma (TSCC) is closely linked to head and neck cancers. Here, we sought to explore the role and mechanism of lncRNAs in the occurrence and progression of TSCC and cisplatin resistance. The results of next-generation transcriptomic sequencing revealed that lncRNA-SNHG26 was differentially expressed and was associated with TSCC cisplatin resistance. The Cancer Genome Atlas dataset and tumor tissue analysis revealed that high SHNG26 expression was associated with the occurrence, progression, and poor prognosis of TSCC. Evidence from cell and animal experiments showed that SNHG26 expression was positively correlated with TSCC proliferation, epithelial-mesenchymal transformation, migration, invasion, and cisplatin resistance. Furthermore, in TSCC cells, SNHG26 was found to bind directly to the PGK1 protein, inhibiting its ubiquitination and activating the Akt/mTOR signaling pathway. These findings suggest that lncRNA-SNHG26 may be a promising target for inhibiting TSCC progression and improving sensitivity to cisplatin chemotherapy in TSCC.

Establishment and Validation of a Ferroptosis-Related Long Non-Coding RNA Signature for Predicting the Prognosis of Stomach Adenocarcinoma

Background: Ferroptosis is a form of regulated cell death that follows cell membrane damage and mostly depends on iron-mediated oxidative. Long non-coding RNAs (LncRNAs) are associated with the development of a variety of tumors. Till date, LncRNAs have been reported to intervene in ferroptosis. Therefore, we intended to provide a prognostic ferroptosis-related-lncRNA signature in stomach adenocarcinoma (STAD).

Methods: We downloaded ferroptosis-related genes from the FerrDb database and RNA sequencing data and clinicopathological characteristics from The Cancer Genome Atlas. Gene differential expression analysis was performed using the “limma” package. We used Cox regression analysis to determine the ferroptosis-related lncRNAs signature with the lowest AIC value. The Kaplan–Meier curve, ROC curve, and nomogram were used to evaluate the prognostic value of the risk score. Gene set enrichment analysis (GSEA) was used to explore the biologic functions of the three ferroptosis-related lncRNAs. LINC01615 expression in gastric cancer cell lines and tissues was measured by real-time PCR. A nuclear-cytoplasmic fractionation assay was used to analyze the subcellular localization for LINC01615. Furthermore, we used bioinformatics to predict potential target microRNAs (miRNAs) of LINC01615 and their target ferroptosis-related mRNAs.

Results: Three ferroptosis-related-lncRNA signatures (AP000695.2, AL365181.3, and LINC01615) were identified, and then Kaplan–Meier, Cox regression analyses, and ROC curve confirmed that the ferroptosis-related-lncRNA model could predict the prognosis of STAD. The GSEA indicated that the three ferroptosis-related lncRNAs might be related to the extracellular matrix and cellular activities. LINC01615 is highly expressed in gastric cancer cell lines and tissues. A nuclear-cytoplasmic fractionation assay confirmed that in gastric cancer cell lines, most LINC01615 was enriched in the cytoplasm. Bioinformatics further predicts four potential target miRNAs of LINC01615 and then figured out 26 target ferroptosis-related mRNAs.

Conclusion: We established a three-ferroptosis-related-lncRNA model (AP000695.2, AL365181.3, and LINC01615) that can predict the prognosis of STAD patients. We also expected to provide a promising target for LINC01615 for research in the future, which was highly expressed in gastric cancer and cell lines and acted as a ceRNA to get involved in ferroptosis.

HIF-1α-activated long non-coding RNA KDM4A-AS1 promotes hepatocellular carcinoma progression via the miR-411-5p/KPNA2/AKT pathway

Hepatocellular carcinoma (HCC) is the most common type of liver cancer with poor clinical outcomes. Long non-coding RNAs (lncRNAs) are extensively involved in the tumorigenesis and progression of HCC. However, more investigations should be carried out on novel lncRNAs and their effects on HCC. Here we identified a novel lncRNA KDM4A-AS1, which was aberrantly overexpressed in HCC tissues, associated with unfavorable clinical features and poor prognosis of patients. KDM4A-AS1 promoted HCC cell proliferation, migration, and invasion in vitro and contributed to HCC growth and lung metastasis in vivo. Mechanistically, KDM4A-AS1 was inversely modulated by miR-411-5p at the post-transcriptional level and facilitated Karyopherin α2 (KPNA2) expression by competitively binding miR-411-5p, thereby activating the AKT pathway. KPNA2 silencing, miR-411-5p overexpression, and AKT inhibitor (MK2206) consistently reversed KDM4A-AS1-enhanced proliferation, mobility, and EMT of HCC cells. KDM4A-AS1 was identified as a novel hypoxia-responsive gene and transactivated by hypoxia-inducible factor 1α (HIF-1α) in HCC cells. In turn, KDM4A-AS1 regulated HIF-1α expression through the KPNA2/AKT signaling pathway. Hence, this study revealed a novel hypoxia-responsive lncRNA, KDM4A-AS1, which contributed to HCC growth and metastasis via the KDM4A-AS1/KPNA2/HIF-1α signaling loop. Our findings provide a promising prognostic and therapeutic target for HCC.

Long Non-Coding RNAs (lncRNAs) in Response and Resistance to Cancer Immunosurveillance and Immunotherapy

Long non-coding RNAs (lncRNAs) are critical regulatory elements in cellular functions in states of both normalcy and disease, including cancer. LncRNAs can influence not only tumorigenesis but also cancer features such as metastasis, angiogenesis and resistance to chemo-and immune-mediated apoptotic signals. Several lncRNAs have been demonstrated to control directly or indirectly the number, type and activities of distinct immune cell populations of adaptive and innate immunities within and without the tumor microenvironment. The disruption of lncRNA expression in both cancer and immune cells may reflect alterations in tumor responses to cancer immunosurveillance and immunotherapy, thus providing new insights into lncRNA biomarker-based prognostic and therapeutic cancer assessment. Here we present an overview on lncRNAs’ functions and underlying molecular mechanisms related to cancer immunity and conventional immunotherapy, with the expectation that any elucidations may lead to a better understanding and management of cancer immune escape and response to current and future immunotherapeutics.

The role of ceRNA-mediated diagnosis and therapy in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death worldwide due to its high degree of malignancy, high incidence, and low survival rate. However, the underlying mechanisms of hepatocarcinogenesis remain unclear. Long non coding RNA (lncRNA) has been shown as a novel type of RNA. lncRNA by acting as ceRNA can participate in various biological processes of HCC cells, such as tumor cell proliferation, migration, invasion, apoptosis and drug resistance by regulating downstream target gene expression and cancer-related signaling pathways. Meanwhile, lncRNA can predict the efficacy of treatment strategies for HCC and serve as a potential target for the diagnosis and treatment of HCC. Therefore, lncRNA serving as ceRNA may become a vital candidate biomarker for clinical diagnosis and treatment. In this review, the epidemiology of HCC, including morbidity, mortality, regional distribution, risk factors, and current treatment advances, was briefly discussed, and some biological functions of lncRNA in HCC were summarized with emphasis on the molecular mechanism and clinical application of lncRNA-mediated ceRNA regulatory network in HCC. This paper can contribute to the better understanding of the mechanism of the influence of lncRNA-mediated ceRNA networks (ceRNETs) on HCC and provide directions and strategies for future studies.

The molecular mechanism of long non-coding ribonucleic acid (lncRNA) RUNX1-IT1 promotes the proliferation and stemness of lung cancer cells

BACKGROUND

This study sought to explore the role of long non-coding ribonucleic acid (lncRNA) RUNX1-IT1 in lung cancer proliferation and cell stemness and clarify its molecular mechanism.

METHODS

Quantitative reverse transcription polymerase chain reaction was used to detect the expression levels of lncRNA RUNX1-IT1 in lung cancer cell lines and tissues. Cell Counting Kit 8, a plate cloning experiment, a cell suspension sphere-forming assay and a Transwell assay were used to identify the effects of lncRNA RUNX1-IT1 overexpression or down-expression on clone formation, cell progression, cell stemness, and invasion. Western blot was used to detect the expression of associated proteins that regulate cell invasion and stemness.

RESULTS

Low expression levels of lncRNA RUNX1-IT1 were detected in the cancerous lung cells and tissues. The overexpression of lncRNA RUNX1-IT1 significantly restricted the ability of cells to proliferate, produce clones, form spheres, and invade lung cancer cells, while the knockdown of lncRNA RUNX1-IT1 had the opposite effect. The findings of the Western blot assessment showed that the overexpression or knockdown of lncRNA RUNX1-IT1 significantly affected the expression of cluster of differentiation 44, cluster of differentiation 133, sex-determining region Y-box 2, octamer-binding transcription factor 4, and Nanog, and regulated the sphere-forming ability of cells. Additionally, the overexpression or knockdown of lncRNA RUNX1-IT1 regulated the invasion ability of cells by affecting expressions of E-cadherin, N-cadherin, and Vimentin.

CONCLUSIONS

The poor expression, overexpression, or knockdown of lncRNA RUNX1-IT1 affects the stemness and invasion ability of lung cancer cells.

A hypoxia related long non-coding RNA signature could accurately predict survival outcomes in patients with bladder cancer

Hypoxia plays a significant role in tumor progression. This study aimed to develop a hypoxia-related long noncoding RNA (lncRNA) signature for predicting survival outcomes of patients with bladder cancer (BC). The transcriptome and clinicopathologic data were downloaded from The Cancer Genome Atlas (TCGA) database. Univariate Cox regression analysis and Lasso regression analysis were used to screened lncRNAs. Ten lncRNAs were screened out and included into the hypoxia lncRNA signature. The risk score based on hypoxia lncRNA signature could accurately predict the survival outcomes of BC patients. Immune infiltration analysis showed that six types of immune cells had significant different infiltration. Tumor mutation burden (TMB) analysis showed that the risk scores between the wild types and the mutation types of TP53, FGFR3, and RB1 were significantly different. Gene Set Enrichment Analysis (GSEA) showed that cancer-associated pathways belonged to the high risk groups and immune-related signal pathways were enriched into the low risk group. Then, we constructed a predictive model with the risk score, age, and clinical stage, which showed a robust prognostic performance. An lncRNA-mRNA coexpression network was constructed, which contained 62 lncRNA-mRNA links among 10 lncRNAs and 40 related mRNAs. In summary, the hypoxia lncRNA signature could accurately predict prognosis, chemotherapy and immunotherapy response in patients with BC and was relevant to clinicopathologic parameters and immune cell infiltration.

Repression of the miR-627-5p by histone deacetylase 3 contributes to hypoxia-induced hepatocellular carcinoma progression

Hepatocellular carcinoma (HCC) is one of the most common solid tumors globally. Our previous studies revealed that miR-627-5p suppresses HCC progression via targeting BCL3/CCND1 pathway. However, the molecular mechanism by which miR-627-5p was downregulated in HCC remains to be further elucidated. As a hallmark of solid tumors, hypoxia results in the rapid growth, strongly potential invasion and high frequent metastasis of cancer cells. Hypoxia-inducible factors (HIFs), mainly including HIF-1 and HIF-2, are the classical transcription factors which mediate hypoxia-related gene transcription. Here, we demonstrated that miR-627-5p was repressed by hypoxia in a HIF-1-dependent manner in HCC cells. But HIF-1 regulated miR-627-5p expression not directly through the hypoxia-response element (HRE) sites of MIR627 gene. In contrast, histone deacetylase 3 (HDAC3) was identified as a HIF-1 target gene, and the occupancy of HIF-1 to HRE site was essential for hypoxia-mediated HDAC3 induction. And upregulated HDAC3 was closely related to the malignant clinical and pathological characteristics and worse prognosis of HCC. Furthermore, HDAC3-mediated histone deacetylation in promoter region of MIR627 was critical for hypoxia-mediated miR-627-5p repression. And miR-627-5p mediated the effects of hypoxic condition on HCC progression. Thus, this study has revealed that miR-627-5p was repressed by hypoxia under the mediation of HDAC3 in HCC, and there existed a HIF-1α/HDAC3/miR-627-5p/BCL3/CCND1 signal pathway in HCC.

HIF-1α-activated TM4SF1-AS1 promotes the proliferation, migration, and invasion of hepatocellular carcinoma cells by enhancing TM4SF1 expression

Long non-coding RNAs (lncRNAs) are essential drivers or suppressors in human hepatocellular carcinoma (HCC) by participating in controlling transcription, translation, mRNA stability, and protein degradation protein-protein interaction. TM4SF1-AS1 is recently identified as a tumor-promoting factor in lung cancer. Nevertheless, its function in HCC and related molecular mechanisms remain unknown. Here, our data indicated that either hypoxia or hypoxia-inducible factor (HIF) prolyl hydroxylase inhibitor (DMOG) induced the upregulation of TM4SF1-AS1 in HCC cells. HIF-1α knockdown rather than HIF-2α silencing remarkably abrogated hypoxia-upregulated TM4SF1-AS1 expression. Furthermore, we confirmed the elevated expression of TM4SF1-AS1 in HCC tissue samples and cell lines. The silencing of TM4SF1-AS1 prominently inhibited the proliferative, migratory, and invasive abilities of HCC cells. TM4SF1-AS1 depletion significantly blocked hypoxia-enhanced Hep3B cell proliferation and mobility. Interfering TM4SF1-AS1 remarkably reduced TM4SF1 mRNA and protein levels in HCC cells. But TM4SF1-AS1 knockdown did not impact the stability of TM4SF1 mRNA. Hypoxia enhanced the expression of TM4SF1 mRNA, which was subsequently decreased by TM4SF1-AS1 knockdown in HCC cells. We confirmed the positive correlation between TM4SF1 mRNA and TM4SF1-AS1 expression in HCC specimens. Finally, TM4SF1 prominently reversed the inhibitory role of TM4SF1-AS1 depletion in Hep3B cells. In summary, hypoxia-responsive TM4SF1-AS1 was overexpressed in human HCC and contributed to the malignant behaviors of tumor cells by enhancing TM4SF1-AS1 expression.

Identification of Cancer Cell Stemness-Associated Long Noncoding RNAs for Predicting Prognosis of Patients with Hepatocellular Carcinoma

Long noncoding RNAs (lncRNAs) are emerging as crucial contributors to the development of hepatocellular carcinoma (HCC) and are involved in the stemness regulation of liver cancer stem cells (LCSCs). However, cancer cell stemness-associated lncRNAs and their relevance in prediction of clinical prognosis remain largely unexplored. In this study, through the transcriptome-wide screen, we identified a total of 136 LCSC-associated lncRNAs. We evaluated the prognostic value of these lncRNAs and optimally established an 11-lncRNA (including AC008622.2, AC015908.3, AC020915.2, AC025176.1, AC026356.2, AC099850.3, CYTOR, DDX11-AS1, HTR2A-AS1, LINC02870, and SNHG3) prognostic risk model. Multivariate analysis revealed that the risk score is an independent prognostic predictor for HCC patients, which outperforms the traditional clinical pathological factors. Gene set enrichment analysis suggested that the high-risk score reflects the alteration of pathways involved in cell cycle, oxidative phosphorylation, and metabolism. Furthermore, functional studies on SNHG12, the leading candidate of the risk lncRNAs, revealed that knockdown of SNHG12 reduces the abilities of HCC cells stemness, proliferation, migration, and invasion. In summary, we constructed a prognostic risk model based on 11 LCSC-associated lncRNAs, which might be a promising prognostic predictor for HCC patients and highlight the involvement of lncRNAs in LCSC-associated treatment strategy in clinical practice.

Regulation of RUNX proteins by long non-coding RNAs and circular RNAs in different cancers

RUNX proteins have been shown to behave as "double-edge sword" in wide variety of cancers. Discovery of non-coding RNAs has played linchpin role in improving our understanding about the post-transcriptional regulation of different cell signaling pathways. Several new mechanistic insights and distinct modes of cross-regulation of RUNX proteins and non-coding RNAs have been highlighted by recent research. In this review we have attempted to provide an intricate interplay between non-coding RNAs and RUNX proteins in different cancers. Better conceptual and mechanistic understanding of layered regulation of RUNX proteins by non-coding RNAs will be helpful in effective translation of the laboratory findings to clinically effective therapeutics.

Novel role of LINC01013/miR-6795-5p/FMNL3 axis in the regulation of hepatocellular carcinoma stem cell features

Cancer stem cells (CSCs) are major contributors to tumor initiation, recurrence, and metastasis of hepatocellular carcinoma (HCC). Some long non-coding RNAs have been reported as modulators of stem-like properties in cancer cells. However, the role of LINC01013 in liver CSCs has not yet been clarified. In this study, we aimed to elucidate the expression pattern and functions of LINC01013 in HCC. HCC tissues and normal controls were collected, and the expression pattern of LINC01013 and miR-6795-5p was identified by quick real-time polymerase chain reaction. Cell counting kit-8 assay, colony formation, and spheroid formation were performed to measure cell viability, proliferation, and self-renewal of HCC cell lines. The expression of stem markers was detected by western blot analysis. The effect of LINC01013 on viability, proliferation, and stem-like properties was detected through gain-of-function and loss-of-function experiments. The direct interaction among LINC01013, miR-6795-5p, and FMNL3 was testified by dual-luciferase reporter gene assay. Tumor-bearing mice were constructed to ascertain the functions of LINC01013 in vivo. HCC tissues showed increased LINC01013 and FMNL3 expression, while it showed a decreased miR-6795-5p expression as compared to the relative controls. Moreover, the high level of LINC01013 was closely related to the poor prognosis of HCC patients. LINC01013 directly binds to miR-6795-5p and subsequently relieves FMNL3. Silencing LINC01013, FMNL3, or overexpression of miR-6795-5p could suppress spheroid and colony formation, proliferation, as well as expression of stemness markers in HepG2 and SNU-182 cells. LINC01013 knockdown suppressed growth and stem-like traits of HCC cells in vivo by reducing FMNL3 expression. LINC01013/miR-6795-5p/FMNL3 axis may be a novel therapeutic target for HCC.

Long noncoding RNA FIRRE contributes to the proliferation and glycolysis of hepatocellular carcinoma cells by enhancing PFKFB4 expression

Recent reports show that long noncoding RNA (lncRNA) FIRRE contributes to the proliferation, apoptosis resistance, and invasion of colorectal cancer and diffuse large B-cell lymphoma. However, the biological function of FIRRE in hepatocellular carcinoma (HCC) remains unknown. Here, we disclosed that the FIRRE level was frequently increased in HCC compared to nontumor tissues. Compared with normal liver cells, we also confirmed the upregulated level of FIRRE in HCC cells. Notably, the FIRRE high expression was related to malignant clinical features, including advanced TNM stage and tumor size ≥5 cm, and conferred to worse survival of HCC. Functionally, FIRRE knockdown repressed the proliferation and glycolysis of HCCLM3 cells. Overexpression of FIRRE strengthened Huh7 cell proliferation and glycolysis. Notably, FIRRE positively regulated the glycolic enzyme 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 4 (PFKFB4) expression in HCC cells. PFKFB4 was highly expressed and positively associated with FIRRE level in HCC tissues. The upregulated expression of PFKFB4 was associated with high tumor grade and advanced TNM stage. TCGA data revealed that the PFKFB4 high expression indicated a poor prognosis of HCC. Mechanistically, modulating FIRRE level did not affect the stability of PFKFB4 mRNA. FIRRE was mainly distributed in HCC cells' nucleus and promoted PFKFB4 transcription and expression via cAMP-responsive element-binding protein (CREB). PFKFB4 could abolish the effects of FIRRE knockdown on HCC cell proliferation and glycolysis. To conclude, the highly expressed FIRRE facilitated HCC cell proliferation and glycolysis by enhancing CREB-mediated PFKFB4 transcription and expression.

LncRNAs link cancer stemness to therapy resistance

Cancer stem cells (CSCs) are a cellular subpopulation accelerating cancer cell growth, invasion and metastasis and survival. After chemoradiotherapy, CSCs are enriched because of their survival advantages and lead to tumor relapse and metastasis. Elimination of CSCs is critically important for the radical treatment of human cancers. Long non-coding RNAs (lncRNAs) are a group of RNAs longer than 200 nucleotides and have no protein-coding potential. Aberrant expressions of lncRNAs are associated with human diseases including cancer. LncRNAs function as cancer biomarkers, prognostic factors and therapeutic targets. They induce cancer stemness by chromatin modification, transcriptional regulation or post-transcriptional regulation of target genes as a sponge or through assembling a scaffold complex. Several factors caused aberrant expressions of lncRNAs in CSCs such as genes mutations, epigenetic alteration and environmental stimuli. Targeting of lncRNAs has been demonstrated to significantly reverse the chemoradioresistance of CSCs. In this review, we have summarized the progress of studies regarding lncRNAs-mediated therapy resistance of CSCs and clarified the molecular mechanisms. Furthermore, we have for the first time analyzed the influences of lncRNAs on cell metabolism and emphasized the effect of tumor microenvironment on lncRNAs functions in CSCs. Overall, the thorough understanding of the association of lncRNAs and CSCs would contribute to the reversal of therapy resistance.

Hypoxia-Induced Cancer Cell Responses Driving Radioresistance of Hypoxic Tumors: Approaches to Targeting and Radiosensitizing

Simple Summary

Some regions of aggressive malignancies experience hypoxia due to inadequate blood supply. Cancer cells adapting to hypoxic conditions somehow become more resistant to radiation exposure and this decreases the efficacy of radiotherapy toward hypoxic tumors. The present review article helps clarify two intriguing points: why hypoxia-adapted cancer cells turn out radioresistant and how they can be rendered more radiosensitive. The critical molecular targets associated with intratumoral hypoxia and various approaches are here discussed which may be used for sensitizing hypoxic tumors to radiotherapy.

Abstract

Within aggressive malignancies, there usually are the “hypoxic zones”—poorly vascularized regions where tumor cells undergo oxygen deficiency through inadequate blood supply. Besides, hypoxia may arise in tumors as a result of antiangiogenic therapy or transarterial embolization. Adapting to hypoxia, tumor cells acquire a hypoxia-resistant phenotype with the characteristic alterations in signaling, gene expression and metabolism. Both the lack of oxygen by itself and the hypoxia-responsive phenotypic modulations render tumor cells more radioresistant, so that hypoxic tumors are a serious challenge for radiotherapy. An understanding of causes of the radioresistance of hypoxic tumors would help to develop novel ways for overcoming this challenge. Molecular targets for and various approaches to radiosensitizing hypoxic tumors are considered in the present review. It is here analyzed how the hypoxia-induced cellular responses involving hypoxia-inducible factor-1, heat shock transcription factor 1, heat shock proteins, glucose-regulated proteins, epigenetic regulators, autophagy, energy metabolism reprogramming, epithelial–mesenchymal transition and exosome generation contribute to the radioresistance of hypoxic tumors or may be inhibited for attenuating this radioresistance. The pretreatments with a multitarget inhibition of the cancer cell adaptation to hypoxia seem to be a promising approach to sensitizing hypoxic carcinomas, gliomas, lymphomas, sarcomas to radiotherapy and, also, liver tumors to radioembolization.

Hypoxia-induced cofilin 1 promotes hepatocellular carcinoma progression by regulating the PLD1/AKT pathway

BACKGROUND

Hepatocellular carcinoma (HCC) is the fourth fatal malignant tumour type worldwide. However, the exact molecular mechanism involved in HCC progression remains unclear.

METHODS

Three pairs of HCC and matched portal vein tumour thrombus (PVTT) tissue samples were analysed by isobaric tags for relative and absolute quantification (iTRAQ) assay to investigate the differentially expressed proteins. Real-time quantitative PCR, immunostaining, and immunoblotting were performed to detect cofilin 1 (CFL1) in HCC and non-tumour tissues. CCK8 and EdU, and Transwell assays, respectively, determined cell proliferation, migration, and invasion of HCC cells. Further, subcutaneous and tail vein injection were performed in nude mice for investigating HCC growth and lung metastasis in vivo. Regulatory effect of hypoxia-inducible factor-1α (HIF-1α) on CFL1 was confirmed by chromatin immunoprecipitation (ChIP) assay. Finally, interaction between CFL1 and phospholipase D1 (PLD1) was studied using immunoprecipitation (IP) assay.

RESULTS

The iTRAQ analysis identified expression of CFL1 to be significantly upregulated in PVTT than in HCC tissues. Increased expression of CFL1 was closely associated with unfavourable clinical features, and was an independent risk predictor of overall survival in HCC patients. The knockdown of CFL1 inhibited cell growth viability, invasiveness, and epithelial-mesenchymal transformation (EMT) in HCC cells. Furthermore, CFL1 silencing significantly suppressed the growth and lung metastasis of HCC cells in nude mice. Next, HIF-1α directly regulated CFL1 transcription by binding to the hypoxia-responsive element (HRE) in the promoter. Moreover, we disclosed the interaction between CFL1 and PLD1 in HCC cells using IP assay. Mechanistically, CFL1 maintained PLD1 expression by repressing ubiquitin-mediated protein degradation, thereby activating AKT signalling in HCC cells. Notably, the CFL1/PLD1 axis was found mediating the hypoxia-induced activation of the AKT pathway and EMT.

CONCLUSION

The analysis suggests that hypoxia-induced CFL1 increases the proliferation, migration, invasion, and EMT in HCC by activating the PLD1/AKT pathway.

Long non-coding RNA MAPKAPK5-AS1/PLAGL2/HIF-1α signaling loop promotes hepatocellular carcinoma progression

Background

Long non-coding RNAs (lncRNAs) are widely involved in human cancers’ progression by regulating tumor cells’ various malignant behaviors. MAPKAPK5-AS1 has been recognized as an oncogene in colorectal cancer. However, the biological role of MAPKAPK5-AS1 in hepatocellular carcinoma (HCC) has not been explored.

Methods

Quantitative real-time PCR was performed to detect the level of MAPKAPK5-AS1 in HCC tissues and cell lines. The effects of MAPKAPK5-AS1 on tumor growth and metastasis were assessed via in vitro experiments, including MTT, colony formation, EdU, flow cytometry, transwell assays, and nude mice models. The western blotting analysis was carried out to determine epithelial-mesenchymal transition (EMT) markers and AKT signaling. The interaction between MAPKAPK5-AS1, miR-154-5p, and PLAGL2 were explored by luciferase reporter assay and RNA immunoprecipitation. The regulatory effect of HIF-1α on MAPKAPK5-AS1 was evaluated by chromatin immunoprecipitation.

Results

MAPKAPK5-AS1 expression was significantly elevated in HCC, and its overexpression associated with malignant clinical features and reduced survival. Functionally, MAPKAPK5-AS1 knockdown repressed the proliferation, mobility, and EMT of HCC cells and induced apoptosis. Ectopic expression of MAPKAPK5-AS1 contributed to HCC cell proliferation and invasion in vitro. Furthermore, MAPKAPK5-AS1 silencing suppressed, while MAPKAPK5-AS1 overexpression enhanced HCC growth and lung metastasis in vivo. Mechanistically, MAPKAPK5-AS1 upregulated PLAG1 like zinc finger 2 (PLAGL2) expression by acting as an endogenous competing RNA (ceRNA) to sponge miR-154-5p, thereby activating EGFR/AKT signaling. Importantly, rescue experiments demonstrated that the miR-154-5p/PLAGL2 axis mediated the function of MAPKAPK5-AS1 in HCC cells. Interestingly, we found that hypoxia-inducible factor 1α (HIF-1α), a transcript factor, could directly bind to the promoter to activate MAPKAPK5-AS1 transcription. MAPKAPK5-AS1 regulated HIF-1α expression through PLAGL2 to form a hypoxia-mediated MAPKAPK5-AS1/PLAGL2/HIF-1α signaling loop in HCC.

Conclusions

Our results reveal a MAPKAPK5-AS1/PLAGL2/HIF-1α signaling loop in HCC progression and suggest that MAPKAPK5-AS1 could be a potential novel therapeutic target of HCC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01868-z.

LncRNA RUNX1-IT1 is Downregulated in Endometrial Cancer and Binds to miR-21 Precursor to Suppress Its Maturation

Background

RUNX1-IT1 suppresses colorectal cancer and liver cancer, while its role in other cancers is unknown. This study was performed to investigate the role of RUNX1-IT1 in endometrial cancer (EC).

Methods

EC and paired non-tumor tissues were collected from 62 EC patients, and the expression of RUNX1-IT1, mature miR-21 and miR-21 precursor in these tissue samples were determined by RT-qPCR. Correlations were analyzed by linear regression. Overexpression of RUNX1-IT1 was achieved in EC cells and the expression of mature miR-21 and miR-21 precursor were analyzed by RT-qPCR. CCK-8 assay was used for cell proliferation analysis.

Results

We found that RUNX1-IT1 was downregulated in EC and inversely correlated with mature miR-21 but not miR-21 precursor. RUNX1-IT1 was predicted to bind with miR-21 precursor. The interaction between them was verified by dual-luciferase activity assay and RNA pull-down assay. In EC cells, overexpression of RUNX1-IT1 downregulated mature miR-21, but not miR-21 precursor. Overexpression of RUNX1-IT1 suppressed the role of miR-21 in increasing cell proliferation.

Conclusion

RUNX1-IT1 is downregulated in EC and inhibits cancer cell proliferation by suppressing the maturation of miR-21.

Thrombospondin 4/integrin α2/HSF1 axis promotes proliferation and cancer stem-like traits of gallbladder cancer by enhancing reciprocal crosstalk between cancer-associated fibroblasts and tumor cells

Background

Cancer-associated fibroblasts (CAFs), the primary component of tumor stroma in tumor microenvironments, are well-known contributors to the malignant progression of gallbladder cancer (GBC). Thrombospondins (THBSs or TSPs) comprise a family of five adhesive glycoproteins that are overexpressed in many types of cancers. However, the expression and potential roles of TSPs in the crosstalk between CAFs and GBC cells has remained unclear.

Methods

Peritumoral fibroblasts (PTFs) and CAFs were extracted from GBC tissues. Thrombospondin expression in GBC was screened by RT-qPCR. MTT viability assay, colony formation, EdU incorporation assay, flow cytometry analysis, Transwell assay, tumorsphere formation and western blot assays were performed to investigate the effects of CAF-derived TSP-4 on GBC cell proliferation, EMT and cancer stem-like features. Subcutaneous tumor formation models were established by co-implanting CAFs and GBC cells or GBC cells overexpressing heat shock factor 1 (HSF1) to evaluate the roles of TSP-4 and HSF1 in vivo. To characterize the mechanism by which TSP-4 is involved in the crosstalk between CAFs and GBC cells, the levels of a variety of signaling molecules were detected by coimmunoprecipitation, immunofluorescence staining, and ELISA assays.

Results

In the present study, we showed that TSP-4, as the stromal glycoprotein, is highly expressed in CAFs from GBC and that CAF-derived TSP-4 induces the proliferation, EMT and cancer stem-like features of GBC cells. Mechanistically, CAF-secreted TSP-4 binds to the transmembrane receptor integrin α2 on GBC cells to induce the phosphorylation of HSF1 at S326 and maintain the malignant phenotypes of GBC cells. Moreover, the TSP-4/integrin α2 axis-induced phosphorylation of HSF1 at S326 is mediated by Akt activation (p-Akt at S473) in GBC cells. In addition, activated HSF1 signaling increased the expression and paracrine signaling of TGF-β1 to induce the transdifferentiation of PTFs into CAFs, leading to their recruitment into GBC and increased TSP-4 expression in CAFs, thereby forming a positive feedback loop to drive the malignant progression of GBC.

Conclusions

Our data indicate that a complex TSP-4/integrin α2/HSF1/TGF-β cascade mediates reciprocal interactions between GBC cells and CAFs, providing a promising therapeutic target for gallbladder cancer patients.

Wnt/β-Catenin Signaling as a Driver of Hepatocellular Carcinoma Progression: An Emphasis on Molecular Pathways

Liver cancers cause a high rate of death worldwide and hepatocellular carcinoma (HCC) is considered as the most common primary liver cancer. HCC remains a challenging disease to treat. Wnt/β-catenin signaling pathway is considered a tumor-promoting factor in various cancers; hence, the present review focused on the role of Wnt signaling in HCC, and its association with progression and therapy response based on pre-clinical and clinical evidence. The nuclear translocation of β-catenin enhances expression level of genes such as c-Myc and MMPs in increasing cancer progression. The mutation of CTNNB1 gene encoding β-catenin and its overexpression can lead to HCC progression. β-catenin signaling enhances cancer stem cell features of HCC and promotes their growth rate. Furthermore, β-catenin prevents apoptosis in HCC cells and increases their migration via triggering EMT and upregulating MMP levels. It is suggested that β-catenin signaling participates in mediating drug resistance and immuno-resistance in HCC. Upstream mediators including ncRNAs can regulate β-catenin signaling in HCC. Anti-cancer agents inhibit β-catenin signaling and mediate its proteasomal degradation in HCC therapy. Furthermore, clinical studies have revealed the role of β-catenin and its gene mutation (CTNBB1) in HCC progression. Based on these subjects, future experiments can focus on developing novel therapeutics targeting Wnt/β-catenin signaling in HCC therapy.

Long non-coding RNA MSC-AS1 facilitates the proliferation and glycolysis of gastric cancer cells by regulating PFKFB3 expression

Long non-coding RNA musculin antisense RNA 1 (lncRNA MSC-AS1) has been recognized as an oncogene in pancreatic cancer, hepatocellular carcinoma, nasopharyngeal carcinoma, and renal cell carcinoma. However, the functional significance of MSC-AS1 and its underlying mechanism in gastric cancer (GC) progression remain unclear. In this study, we demonstrated that the expression of MSC-AS1 in GC tissues was significantly higher than that in non-tumor tissues. Moreover, the elevated level of MSC-AS1 was detected in GC cells (MKN-45, AGS, SGC-7901, and MGC-803) compared to normal GES-1 gastric mucosal cells. The cancer genome atlas (TCGA) data further indicated that the high level of MSC-AS1 was closely correlated with advanced tumor stage and poor prognosis of GC. Next, we revealed that MSC-AS1 knockdown inhibited the proliferation, glucose consumption, lactate production, and pyruvate production of MGC-803 cells. Conversely, MSC-AS1 overexpression enhanced the proliferation and glycolysis of AGC cells. Mechanistically, modulating MSC-AS1 level affected the expression of 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3), but did not impact the levels of hexokinase 2 (HK2) and pyruvate kinase M2 (PKM2) in GC cells. Based on this, we reversed the MSC-AS1 knockdown-induced the inhibition of cell proliferation and glycolysis by restoring PFKFB3 expression in MGC-803 cells. In conclusion, MSC-AS1 facilitated the proliferation and glycolysis of GC cells by maintaining PFKFB3 expression.

Hepigenetics: A Review of Epigenetic Modulators and Potential Therapies in Hepatocellular Carcinoma

Hepatocellular carcinoma is the fifth most common cancer worldwide and the second most lethal, following lung cancer. Currently applied therapeutic practices rely on surgical resection, chemotherapy and radiotherapy, or a combination thereof. These treatment options are associated with extreme adversities, and risk/benefit ratios do not always work in patients' favor. Anomalies of the epigenome lie at the epicenter of aberrant molecular mechanisms by which the disease develops and progresses. Modulation of these anomalous events poses a promising prospect for alternative treatment options, with an abundance of felicitous results reported in recent years. Herein, the most recent epigenetic modulators in hepatocellular carcinoma are recapitulated on.

Interplay of long non-coding RNAs and HIF-1α: A new dimension to understanding hypoxia-regulated tumor growth and metastasis

Hypoxia is a feature of the solid tumor microenvironment that is associated with poor clinical outcomes in multiple tumor types. Hypoxia-induced factor-1 alpha (HIF-1α) is a master regulator of hypoxic adaption, has been demonstrated to modulate hypoxic gene expression profiling and signaling transduction networks, and is thus a potential therapeutic target. Despite hypoxic response signaling having being extensively studied, the involvement of long non-coding RNAs (lncRNAs) in the hypoxic response has become a new focus of attention. Emerging evidence has documented complex interactions between HIF-1α and lncRNAs, which contribute to the acquisition of multiple hallmarks of cancer. In this review, we focus on recent advances in the study of hypoxia and HIF-1α-regulated lncRNAs, and summarize the molecular mechanisms and functional outcomes of the interplay between lncRNAs and HIF-1α, which may provide important insights into cancer diagnosis and prognosis, enabling better control of cancer.

Hypoxia-Inducible Ubiquitin Specific Peptidase 13 Contributes to Tumor Growth and Metastasis via Enhancing the Toll-Like Receptor 4/Myeloid Differentiation Primary Response Gene 88/Nuclear Factor-κB Pathway in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer death worldwide. The activation of the toll-like receptor 4/myeloid differentiation primary response gene 88/nuclear factor-κB (TLR4/MyD88/NF-κB) pathway contributes to the development and progression of HCC. The ubiquitin-proteasome system regulates TLR4 expression. However, whether ubiquitin specific peptidase 13 (USP13) stabilizes TLR4 and facilitates HCC progression remains unclear. Here, quantitative real-time PCR (qRT-PCR) and immunohistochemistry analysis revealed that USP13 expression in HCC tissues was higher than in non-tumor liver tissues. Moreover, the elevated expression of USP13 was detected in HCC cells (SK-HEP-1, HepG2, Huh7, and Hep3B) compared to LO2 cells. Interestingly, the positive staining of USP13 was closely correlated with tumor size ≥ 5 cm and advanced tumor stage and conferred to significantly lower survival of HCC patients. Next, USP13 knockdown prominently reduced the proliferation, epithelial-mesenchymal transition (EMT), migration, and invasion of Hep3B and Huh7 cells, while USP13 overexpression enhanced these biological behaviors of HepG2 and LO2 cells. The silencing of USP13 significantly restrained the growth and lung metastasis of HCC cells in vivo. Mechanistically, the USP13 depletion markedly inhibited the TLR4/MyD88/NF-κB pathway in HCC cells. USP13 interacted with TLR4 and inhibited the ubiquitin-mediated degradation of TLR4. Significantly, TLR4 re-expression remarkably reversed the effects of USP13 knockdown on HCC cells. USP13 expression was markedly upregulated in HCC cells under hypoxia conditions. Notably, USP13 knockdown repressed hypoxia-induced activation of the TLR4/MyD88/NF-κB pathway in HCC cells. In conclusion, our study uncovered that hypoxia-induced USP13 facilitated HCC progression via enhancing TLR4 deubiquitination and subsequently activating the TLR4/MyD88/NF-κB pathway.

Hypoxia-inducible long noncoding RNA NPSR1-AS1 promotes the proliferation and glycolysis of hepatocellular carcinoma cells by regulating the MAPK/ERK pathway

Hepatocellular carcinoma (HCC), which accounts for approximately 90% of primary liver cancer, is commonly treated with surgical resection. However, most patients lose the opportunity to receive this therapeutic strategy due to delayed diagnosis and rapid tumor progression. Long noncoding RNAs (lncRNAs) have been demonstrated to play essential roles in the initiation and progression of HCC. However, the function of the novel lncRNA neuropeptide S receptor 1 antisense RNA 1 (NPSR1-AS1) in HCC and its potential mechanism, is unclear. Here, our microarray data revealed NPSR1-AS1 as a novel hypoxia-responsive lncRNA in HCC cells. Interestingly, hypoxia-inducible factor-1α (HIF-1α) knockdown abolished hypoxia-induced NPSR1-AS1 expression in HCC cells. NPSR1-AS1 expression was upregulated in HCC tissues and cell lines. Next, the ectopic expression of NPSR1-AS1 facilitated the proliferation and glycolysis of HCC cells. In contrast, NPSR1-AS1 silencing repressed HCC cell proliferation and glycolysis. Mechanistically, NPSR1-AS1 overexpression increased the levels of p-ERK1/2 and pyruvate kinase M2 (PKM2) in HCC cells. NPSR1-AS1 knockdown abrogated hypoxia-induced the activation of the MAPK/ERK pathway in HCC cells. Importantly, NPSR1-AS1 depletion partially reversed hypoxia-induced proliferation and glycolysis of HCC cells in vitro. In conclusion, hypoxia-inducible NPSR1-AS1 promotes the proliferation and glycolysis of HCC cells, possibly by regulating the MAPK/ERK pathway, suggesting an underlying therapeutic strategy for HCC.