Nutrient Stress-Dysregulated Antisense lncRNA GLS-AS Impairs GLS-Mediated Metabolism and Represses Pancreatic Cancer Progression

HuR controls glutaminase RNA metabolism

Glutaminase (GLS) is directly related to cell growth and tumor progression, making it a target for cancer treatment. The RNA-binding protein HuR (encoded by the ELAVL1 gene) influences mRNA stability and alternative splicing. Overexpression of ELAVL1 is common in several cancers, including breast cancer. Here we show that HuR regulates GLS mRNA alternative splicing and isoform translation/stability in breast cancer. Elevated ELAVL1 expression correlates with high levels of the glutaminase isoforms C (GAC) and kidney-type (KGA), which are associated with poor patient prognosis. Knocking down ELAVL1 reduces KGA and increases GAC levels, enhances glutamine anaplerosis into the TCA cycle, and drives cells towards glutamine dependence. Furthermore, we show that combining chemical inhibition of GLS with ELAVL1 silencing synergistically decreases breast cancer cell growth and invasion. These findings suggest that dual inhibition of GLS and HuR offers a therapeutic strategy for breast cancer treatment.

Emerging roles of long noncoding RNAs in enzymes related intracellular metabolic pathways in cancer biology

Metabolic reprogramming plays critical roles in the development and progression of tumor by providing cancer cells with a sufficient supply of nutrients and other factors needed for fast-proliferating. Emerging evidence indicates that long noncoding RNAs (lncRNAs) are involved in the initiation of metastasis via regulating the metabolic reprogramming in various cancers. In this paper, we aim to summarize that lncRNAs could participate in intracellular nutrient metabolism including glucose, amino acid, lipid, and nucleotide, regardless of whether lncRNAs have tumor-promoting or tumor-suppressor function. Meanwhile, modulation of lncRNAs in glucose metabolic enzymes in glycolysis, pentose phosphate pathway and tricarboxylic acid cycle (TCA) in cancer is reviewed. We also discuss therapeutic strategies targeted at interfering with enzyme activity to decrease the utilization of glucoses, amino acid, nucleotide acid and lipid in tumor cells. This review focuses on our current understanding of lncRNAs participating in cancer cell metabolic reprogramming, paving the way for further investigation into the combination of such approaches with existing anti-cancer therapies.

The role of AMPK in pancreatic cancer: from carcinogenesis to treatment

Pancreatic cancer has doubled over the previous two decades. Routine therapies are becoming incredibly resistant and failing to compensate for the burden caused by this aggressive neoplasm. As genetic susceptibility has always been a highlighted concern for this disease, identifying the molecular pathways involved in the survival and function of pancreatic cancer cells provides insight into its variant etiologies, one of which is the role of AMPK. This regulating factor of cell metabolism is crucial in the homeostasis and growth of the cell. Herein, we review the possible role of AMPK in pancreatic cancer while considering its leading effects on glycolysis and autophagy. Then, we assess the probable therapeutic agents that have resulted from the suggested pathways. Studying the underlying genetic changes in pancreatic cancer provides a chance to detect and treat patients suffering from advanced stages of the disease, and those who have given up their hope on conventional therapies can gain an opportunity to combat this cancer.

Transcriptomic profiling and risk assessment in bladder cancer: Insights from copper death-related genes

BACKGROUND

The study aimed to investigate the role of copper death-related genes (CRGs) in bladder cancer (BC) for improved prognosis assessment.

METHODS

Multi-omics techniques were utilized to analyze CRG expression in BC tissues from TCGA and GEO databases. Consensus clustering categorized patients into molecular subtypes based on clinical characteristics and immune cell infiltration.

RESULTS

An innovative risk assessment model identified eight critical genes associated with BC risk. In vitro and in vivo experiments validated LIPT1's significant impact on copper-induced cell death, proliferation, migration, and invasion in BC.

CONCLUSION

This multi-omics analysis elucidates the pivotal role of CRGs in BC progression, suggesting enhanced risk assessment through molecular subtype categorization and identification of key genes like LIPT1. Insights into these mechanisms offer the potential for improved diagnosis and treatment strategies for BC patients.

Energy stress-induced circDDX21 promotes glycolysis and facilitates hepatocellular carcinogenesis

Cancer cells undergo metabolic reprogramming in response to hostile microenvironments, such as energy stress; however, the underlying mechanisms remain largely unclear. It is also unknown whether energy stress-responsive circular RNA (circRNA) is involved in the regulation of glucose metabolism. Here we report that circDDX21 is upregulated in response to glucose deprivation by the transcription factor c-Myc. Functionally, circDDX21 is shown to promote glycolysis by increasing PGAM1 expression. Mechanistically, circDDX21 interacts with the RNA binding protein PABPC1, disrupting its association with the ubiquitin E3 ligase MKRN3. This disassociation attenuates MKRN3-mediated PABPC1 ubiquitination and enhances the binding of PABPC1 to PGAM1 mRNA, thereby leading to PGAM1 mRNA stabilization. The ability of the circDDX21-PGAM1 axis to promote hepatocellular carcinogenesis is validated in a xenograft mouse model. Additionally, in clinical hepatocellular carcinoma tissues, there is a positive correlation between circDDX21 and PGAM1 expression. These findings establish circDDX21 as an important regulator of glycolysis and suggest circDDX21 as a potential therapeutic target for hepatocellular carcinoma.

Role of long non-coding RNAs in metabolic reprogramming of gastrointestinal cancer cells

Metabolic reprogramming, which is recognized as a hallmark of cancer, refers to the phenomenon by which cancer cells change their metabolism to support their increased biosynthetic demands. Tumor cells undergo substantial alterations in metabolic pathways, such as glycolysis, oxidative phosphorylation, pentose phosphate pathway, tricarboxylic acid cycle, fatty acid metabolism, and amino acid metabolism. Latest studies have revealed that long non-coding RNAs (lncRNAs), a group of non-coding RNAs over 200 nucleotides long, mediate metabolic reprogramming in tumor cells by regulating the transcription, translation and post-translational modification of metabolic-related signaling pathways and metabolism-related enzymes through transcriptional, translational, and post-translational modifications of genes. In addition, lncRNAs are closely related to the tumor microenvironment, and they directly or indirectly affect the proliferation and migration of tumor cells, drug resistance and other processes. Here, we review the mechanisms of lncRNA-mediated regulation of glucose, lipid, amino acid metabolism and tumor immunity in gastrointestinal tumors, aiming to provide more information on effective therapeutic targets and drug molecules for gastrointestinal tumors.

Phytochemicals Target Multiple Metabolic Pathways in Cancer

Cancer metabolic reprogramming is a complex process that provides malignant cells with selective advantages to grow and propagate in the hostile environment created by the immune surveillance of the human organism. This process underpins cancer proliferation, invasion, antioxidant defense, and resistance to anticancer immunity and therapeutics. Perhaps not surprisingly, metabolic rewiring is considered to be one of the "Hallmarks of cancer". Notably, this process often comprises various complementary and overlapping pathways. Today, it is well known that highly selective inhibition of only one of the pathways in a tumor cell often leads to a limited response and, subsequently, to the emergence of resistance. Therefore, to increase the overall effectiveness of antitumor drugs, it is advisable to use multitarget agents that can simultaneously suppress several key processes in the tumor cell. This review is focused on a group of plant-derived natural compounds that simultaneously target different pathways of cancer-associated metabolism, including aerobic glycolysis, respiration, glutaminolysis, one-carbon metabolism, de novo lipogenesis, and β-oxidation of fatty acids. We discuss only those compounds that display inhibitory activity against several metabolic pathways as well as a number of important signaling pathways in cancer. Information about their pharmacokinetics in animals and humans is also presented. Taken together, a number of known plant-derived compounds may target multiple metabolic and signaling pathways in various malignancies, something that bears great potential for the further improvement of antineoplastic therapy.

Long non-coding RNAs and pancreatic cancer: A multifaceted view

Pancreatic cancer (PC) is a highly malignant disease with a 5-year survival rate of only 10%. Families with PC are at greater risk, as are type 2 diabetes, pancreatitis, and other factors. Insufficient early detection methods make this cancer have a poor prognosis. Additionally, the molecular mechanisms underlying PC development remain unclear. Increasing evidence suggests that long non-coding RNAs (lncRNAs) contribute to PC pathology,which may control gene expression by recruiting histone modification complexes to chromatin and interacting with proteins and RNAs. In recent studies, abnormal regulation of lncRNAs has been implicated in PC proliferation, metastasis, invasion, angiogenesis, apoptosis, and chemotherapy resistance suggesting potential clinical implications. The paper reviews the progress of lncRNA research in PC about diabetes mellitus, pancreatitis, cancer metastasis, tumor microenvironment regulation, and chemoresistance. Furthermore, lncRNAs may serve as potential therapeutic targets and biomarkers for PC diagnosis and prognosis. This will help improve PC patients' survival rate from a lncRNA perspective.

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.

Glutamine metabolism in tumor metastasis: Genes, mechanisms and the therapeutic targets

Cancer cells frequently change their metabolism from aerobic glycolysis to lipid metabolism and amino acid metabolism to adapt to the malignant biological behaviours of infinite proliferation and distant metastasis. The significance of metabolic substances and patterns in tumour cell metastasis is becoming increasingly prominent. Tumour metastasis involves a series of significant steps such as the shedding of cancer cells from a primary tumour, resistance to apoptosis, and colonisation of metastatic sites. However, the role of glutamine in these processes remains unclear. This review summarises the key enzymes and transporters involved in glutamine metabolism that are related to the pathogenesis of malignant tumour metastasis. We also list the roles of glutamine in resisting oxidative stress and promoting immune escape. Finally, the significance of targeting glutamine metabolism in inhibiting tumour metastasis was proposed, research in this field improving our understanding of amino acid metabolism rewiring and simultaneously bringing about new and exciting therapeutic prospects.

Metabolic stress-induced reciprocal loop of long noncoding RNA ZFAS1 and ZEB1 promotes epithelial-mesenchymal transition and metastasis of pancreatic cancer cells

Pancreatic cancer (PC) development faces significant metabolic stress due to metabolic reprogramming and a distinct hypovascular nature, often leading to glucose and glutamine depletion. However, the adaption mechanisms by which PC adapts to these metabolic challenges have not yet been completely explored. Here, we found that metabolic stress induced by glucose and glutamine deprivation led to an overexpression of ZNFX1 antisense RNA 1 (ZFAS1). This overexpression played a significant role in instigating PC cell epithelial-mesenchymal transition (EMT) and metastasis. Mechanistically, ZFAS1 enhanced the interaction between AMPK, a key kinase, and ZEB1, the primary regulator of EMT. This interaction resulted in the phosphorylation and subsequent stabilization of ZEB1. Interestingly, ZEB1 also reciprocally influenced the transcription of ZFAS1 by binding to its promoter. Furthermore, when ZFAS1 was depleted, the nutrient deprivation-induced EMT of PC cells and lung metastasis in nude mice were significantly inhibited. Our investigations also revealed that ZFAS1-rich exosomes released from cells suffering glucose and glutamine deprivation promoted the EMT and metastasis of recipient PC cells. Corroborating these findings, a correlated upregulation of ZFAS1 and ZEB1 expression was observed in PC tissues and was associated with a poor overall survival rate for patients. Our findings highlight the involvement of a long noncoding RNA-driven metabolic adaptation in promoting EMT and metastasis of PC, suggesting ZFAS1 as a promising novel therapeutic target for PC metabolic treatment.

Long non-coding RNAs modulate tumor microenvironment to promote metastasis: novel avenue for therapeutic intervention

Cancer is a devastating disease and the primary cause of morbidity and mortality worldwide, with cancer metastasis responsible for 90% of cancer-related deaths. Cancer metastasis is a multistep process characterized by spreading of cancer cells from the primary tumor and acquiring molecular and phenotypic changes that enable them to expand and colonize in distant organs. Despite recent advancements, the underlying molecular mechanism(s) of cancer metastasis is limited and requires further exploration. In addition to genetic alterations, epigenetic changes have been demonstrated to play an important role in the development of cancer metastasis. Long non-coding RNAs (lncRNAs) are considered one of the most critical epigenetic regulators. By regulating signaling pathways and acting as decoys, guides, and scaffolds, they modulate key molecules in every step of cancer metastasis such as dissemination of carcinoma cells, intravascular transit, and metastatic colonization. Gaining a good knowledge of the detailed molecular basis underlying lncRNAs regulating cancer metastasis may provide previously unknown therapeutic and diagnostic lncRNAs for patients with metastatic disease. In this review, we concentrate on the molecular mechanisms underlying lncRNAs in the regulation of cancer metastasis, the cross-talk with metabolic reprogramming, modulating cancer cell anoikis resistance, influencing metastatic microenvironment, and the interaction with pre-metastatic niche formation. In addition, we also discuss the clinical utility and therapeutic potential of lncRNAs for cancer treatment. Finally, we also represent areas for future research in this rapidly developing field.

Oncogenic roles and related mechanisms of the long non-coding RNA MINCR in human cancers

Long non-coding RNAs (lncRNAs) play vital roles in regulating epigenetic mechanisms and gene expression levels, and their dysregulation is closely associated with a variety of diseases such as cancer. Several studies have demonstrated that lncRNAs are dysregulated during tumor progression. Recently, the MYC-induced long non-coding RNA MINCR, a newly identified lncRNA, has been demonstrated to act as an oncogene in different cancers, including gallbladder cancer, hepatocellular cancer, colorectal cancer, non-small cell lung cancer, oral squamous cell carcinoma, nasopharyngeal cancer, and glioma. Moreover, MINCR has been reported to act as a biomarker in the prognosis of patients with different cancers. In this review, we summarize and analyze the oncogenic roles of MINCR in a variety of human cancers in terms of its clinical significance, biological functions, cellular activities, and regulatory mechanism. Our analysis of the literature suggests that MINCR has potential as a novel biomarker and therapeutic target in human cancers.

Amino acid metabolism regulated by lncRNAs: the propellant behind cancer metabolic reprogramming

Metabolic reprogramming is one of the main characteristics of cancer cells and plays pivotal role in the proliferation and survival of cancer cells. Amino acid is one of the key nutrients for cancer cells and many studies have focused on the regulation of amino acid metabolism, including the genetic alteration, epigenetic modification, transcription, translation and post-translational modification of key enzymes in amino acid metabolism. Long non-coding RNAs (lncRNAs) are composed of a heterogeneous group of RNAs with transcripts of more than 200 nucleotides in length. LncRNAs can bind to biological molecules such as DNA, RNA and protein, regulating the transcription, translation and post-translational modification of target genes. Now, the functions of lncRNAs in cancer metabolism have aroused great research interest and significant progress has been made. This review focuses on how lncRNAs participate in the reprogramming of amino acid metabolism in cancer cells, especially glutamine, serine, arginine, aspartate, cysteine metabolism. This will help us to better understand the regulatory mechanism of cancer metabolic reprogramming and provide new ideas for the development of anti-cancer drugs. Video Abstract.

Targeting glutaminase 1 (GLS1) by small molecules for anticancer therapeutics

Glutaminase-1 (GLS1) is a critical enzyme involved in several cellular processes, and its overexpression has been linked to the development and progression of cancer. Based on existing research, GLS1 plays a crucial role in the metabolic activities of cancer cells, promoting rapid proliferation, cell survival, and immune evasion. Therefore, targeting GLS1 has been proposed as a promising cancer therapy strategy, with several GLS1 inhibitors currently under development. To date, several GLS1 inhibitors have been identified, which can be broadly classified into two types: active site and allosteric inhibitors. Despite their pre-clinical effectiveness, only a few number of these inhibitors have advanced to initial clinical trials. Hence, the present medical research emphasizes the need for developing small molecule inhibitors of GLS1 possessing significantly high potency and selectivity. In this manuscript, we aim to summarize the regulatory role of GLS1 in physiological and pathophysiological processes. We also provide a comprehensive overview of the development of GLS1 inhibitors, focusing on multiple aspects such as target selectivity, in vitro and in vivo potency and structure-activity relationships.

Alone and together: current approaches to targeting glutaminase enzymes as part of anti-cancer therapies

Metabolic reprogramming is a major hallmark of malignant transformation in cancer, and part of the so-called Warburg effect, in which the upregulation of glutamine catabolism plays a major role. The glutaminase enzymes convert glutamine to glutamate, which initiates this pathway. Inhibition of different forms of glutaminase (KGA, GAC, or LGA) demonstrated potential as an emerging anti-cancer therapeutic strategy. The regulation of these enzymes, and the molecular basis for their inhibition, have been the focus of much recent research. This review will explore the recent progress in understanding the molecular basis for activation and inhibition of different forms of glutaminase, as well as the recent focus on combination therapies of glutaminase inhibitors with other anti-cancer drugs.

The LncRNA signature associated with cuproptosis as a novel biomarker of prognosis in immunotherapy and drug screening for clear cell renal cell carcinoma

Cuproptosis is a new form of cell death, the second form of metal ion-induced cell death defined after ferroptosis. Recently, cuproptosis has been suggested to be associated with tumorigenesis. However, the relationship between cuproptosis and patient prognosis in clear cell renal cell carcinoma (ccRCC) in the context of immunotherapy remains unknown. The aim of this study was to investigate the correlation between cuproptosis-related long non-coding RNA (lncRNA) and ccRCC in terms of immunity as well as prognosis. Clinical information on lncRNAs associated with differences in cuproptosis genes in ccRCC and normal tissues was collected from The Cancer Genome Atlas (TCGA) dataset. Univariate Cox regression was used to screen lncRNAs. A total of 11 lncRNAs closely associated with cuproptosis were further screened and established using the least absolute shrinkage and selection operator (LASSO) algorithm and multivariate Cox regression, and the samples were randomly divided into training and test groups. A risk prognostic model was constructed using the training group, and the model was validated using the test group. We investigated the predictive ability of the prognostic risk model in terms of clinical prognosis, tumor mutation, immune escape, immunotherapy, tumor microenvironment, immune infiltration levels, and tumor drug treatment of ccRCC. Using the median risk score, patients were divided into low and high-risk groups. Kaplan-Meier curves showed that the overall survival (OS) of patients in the high-risk group was significantly worse than low-risk group (p < 0.001). Receiver operating characteristic (ROC) curves further validated the reliability of our model. The model consistently and accurately predicted prognosis at 1, 3, and 5 years, with an AUC above 0.7. Tumor cell genes generally precede morphological abnormalities; therefore, the model we constructed can effectively compensate for the traditional method of evaluating the prognosis of patients with renal cancer, and our model was also clinically meaningful in predicting ccRCC staging. In addition, lower model risk scores determined by mutational load indicated a good chance of survival. The high-risk group had greater recruitment of immune cells, while the anti-immune checkpoint immunotherapy was less efficacious overall than that of the low-risk group. Tumor and immune-related pathways were enriched, and anti-tumor agents were selected to improve the survival of ccRCC. This prognostic risk model is based on the levels of cuproptosis-associated lncRNAs and provides a new perspective in the clinical assessment and precise treatment of ccRCC.

Development and validation of a novel ferroptosis‑related lncRNA prognostic signature for pancreatic adenocarcinoma

Long non‑coding RNAs (lncRNAs) serve a pivotal role in the regulation of cancer cell ferroptosis. However, the prognostic value of ferroptosis‑related lncRNAs in pancreatic adenocarcinoma (PAAD) largely remains unclear. We aimed at constructing a lncRNA‑based signature to improve the prognosis prediction of PAAD. In the present study, the transcriptome profiling data and clinical information of patients with PAAD were obtained from The Cancer Genome Atlas (TCGA) and International Cancer Gene Consortium (ICGC) databases. Univariate Cox regression analysis of the TCGA cohort demonstrated that 26 ferroptosis‑related lncRNAs had significant prognostic value for PAAD (all P<0.01). Least absolute shrinkage and selection operator regression and multivariate Cox proportional hazards regression analyses were performed to construct a prognostic ferroptosis‑related lncRNA signature (FRLS) comprising nine ferroptosis‑related lncRNAs. The efficacy of this FRLS was verified in the training (TCGA) and validation (ICGC) cohorts. Based on the risk model, high risk scores were significantly correlated with poor overall survival (OS) (hazard ratio, 1.314; 95% confidence interval, 1.218‑1.418; P<0.001). The receiver operating characteristic curves and principal component analysis further demonstrated the robust prognostic ability of the FRLS. Furthermore, a nomogram with favorable predictive efficacy for the prediction of OS was constructed based on the FRLS and clinical features. Gene set enrichment analysis demonstrated that the genes in the FRLS participated in a number of cancer‑associated immunoregulatory pathways. Importantly, it was demonstrated that immune infiltration and response to cancer immunotherapy differed significantly between the high and low‑risk groups according to the FRLS. In conclusion, the risk signature based on the FRLS has potential for the clinical prediction of prognosis and immunotherapy response in patients with PAAD.

SMYD2 Promotes Hepatocellular Carcinoma Progression by Reprogramming Glutamine Metabolism via c-Myc/GLS1 Axis

Metabolic reprogramming, such as alterations in glutamine metabolism or glycolysis, is the hallmark of hepatocellular carcinoma (HCC). However, the underlying mechanisms are still incompletely elucidated. Previous studies have identified that methyltransferase SET and MYND domain-containing protein 2(SMYD2) is responsible for the pathogenesis of numerous types of cancer. Here, we innovatively uncover how SMYD2 regulates glutamine metabolism in HCC cells and promotes HCC progression. We identified that SMYD2 expression is upregulated in HCC tissues, which correlates with unfavorable clinical outcomes. Our in vitro and in vivo results showed that the depletion of SMYD2 inhibits HCC cell growth. Mechanistically, c-Myc methylation by SMYD2 increases its protein stability through the ubiquitin-proteasome system. We showed SMYD2 depletion destabilized c-Myc protein by increasing the conjugated K48-linked polyubiquitin chain. SMYD2 increased c-Myc expression and further upregulated glutaminase1 (GLS1), a crucial enzyme that catalyzes the conversion of glutamine to glutamic acid, in HCC cells. GLS1 plays an important role in SMYD2-mediated HCC progression and glutamine metabolism regulation. The knockdown of SMYD2 inhibited glutamine metabolism in HCC cells and overcame their chemoresistance to sorafenib. Collectively, our findings demonstrated a novel mechanism of how SMYD2 promotes HCC progression by regulating glutamine metabolism through the c-Myc/GLS1signaling, implicating the therapeutic potential of targeting SMYD2 in HCC patients.

The Involvement of Long Non-Coding RNAs in Glutamine-Metabolic Reprogramming and Therapeutic Resistance in Cancer

Metabolic alterations that support the supply of biosynthetic molecules necessary for rapid and sustained proliferation are characteristic of cancer. Some cancer cells rely on glutamine to maintain their energy requirements for growth. Glutamine is an important metabolite in cells because it not only links to the tricarboxylic acid cycle by producing α-ketoglutarate by glutaminase and glutamate dehydrogenase but also supplies other non-essential amino acids, fatty acids, and components of nucleotide synthesis. Altered glutamine metabolism is associated with cancer cell survival, proliferation, metastasis, and aggression. Furthermore, altered glutamine metabolism is known to be involved in therapeutic resistance. In recent studies, lncRNAs were shown to act on amino acid transporters and glutamine-metabolic enzymes, resulting in the regulation of glutamine metabolism. The lncRNAs involved in the expression of the transporters include the abhydrolase domain containing 11 antisense RNA 1, LINC00857, plasmacytoma variant translocation 1, Myc-induced long non-coding RNA, and opa interacting protein 5 antisense RNA 1, all of which play oncogenic roles. When it comes to the regulation of glutamine-metabolic enzymes, several lncRNAs, including nuclear paraspeckle assembly transcript 1, XLOC_006390, urothelial cancer associated 1, and thymopoietin antisense RNA 1, show oncogenic activities, and others such as antisense lncRNA of glutaminase, lincRNA-p21, and ataxin 8 opposite strand serve as tumor suppressors. In addition, glutamine-dependent cancer cells with lncRNA dysregulation promote cell survival, proliferation, and metastasis by increasing chemo- and radio-resistance. Therefore, understanding the roles of lncRNAs in glutamine metabolism will be helpful for the establishment of therapeutic strategies for glutamine-dependent cancer patients.

Crosstalk between metabolic reprogramming and epigenetics in cancer: updates on mechanisms and therapeutic opportunities

Reversible, spatial, and temporal regulation of metabolic reprogramming and epigenetic homeostasis are prominent hallmarks of carcinogenesis. Cancer cells reprogram their metabolism to meet the high bioenergetic and biosynthetic demands for vigorous proliferation. Epigenetic dysregulation is a common feature of human cancers, which contributes to tumorigenesis and maintenance of the malignant phenotypes by regulating gene expression. The epigenome is sensitive to metabolic changes. Metabolism produces various metabolites that are substrates, cofactors, or inhibitors of epigenetic enzymes. Alterations in metabolic pathways and fluctuations in intermediate metabolites convey information regarding the intracellular metabolic status into the nucleus by modulating the activity of epigenetic enzymes and thus remodeling the epigenetic landscape, inducing transcriptional responses to heterogeneous metabolic requirements. Cancer metabolism is regulated by epigenetic machinery at both transcriptional and post‐transcriptional levels. Epigenetic modifiers, chromatin remodelers and non‐coding RNAs are integral contributors to the regulatory networks involved in cancer metabolism, facilitating malignant transformation. However, the significance of the close connection between metabolism and epigenetics in the context of cancer has not been fully deciphered. Thus, it will be constructive to summarize and update the emerging new evidence supporting this bidirectional crosstalk and deeply assess how the crosstalk between metabolic reprogramming and epigenetic abnormalities could be exploited to optimize treatment paradigms and establish new therapeutic options. In this review, we summarize the central mechanisms by which epigenetics and metabolism reciprocally modulate each other in cancer and elaborate upon and update the major contributions of the interplays between epigenetic aberrations and metabolic rewiring to cancer initiation and development. Finally, we highlight the potential therapeutic opportunities for hematological malignancies and solid tumors by targeting this epigenetic‐metabolic circuit. In summary, we endeavored to depict the current understanding of the coordination between these fundamental abnormalities more comprehensively and provide new perspectives for utilizing metabolic and epigenetic targets for cancer treatment.

Cuproptosis-related gene signatures for predicting prognosis of lung adenocarcinoma

Lung cancer (LC) is a common malignancy with high mortality rate, and lung adenocarcinoma (LUAD) is one of the common pathological types. Cuproptosis is a recently discovered new type of cell death dependent on mitochondria. However, the role of cuproptosis in LUAD is unknown. We obtained LUAD transcriptome data from the Cancer Genome Atlas (TCGA). Long-stranded non-coding RNA (LncRNAs) based on cuproptosis prognosis associated with LUAD were constructed for prognostic multi-LncRNA characterization. We divided TCGA-LUAD into training set and validation set to prove feasibility, and all samples were divided into high-risk group or low risk group. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were used to evaluate potential biological functions and explore the relationship between risk models and immunity. We identified 3 differentially expressed LncRNAs associated with LUAD prognosis and constructed prognostic model. Kaplan-Meier (K-M) analysis revealed prognostic model and LUAD prognosis. Our risk assessment model has a good reliability in predicting the prognosis of LUAD and was able to improve predictive ability of tumor mutational burdern. Single sample gene enrichment analysis (ssGSEA) revealed risk subgroups were associated with immune-related functions. The prognostic model based on cuproptosis lncRNA has important value in predicting the survival of LUAD patients.

Implications of a Neuronal Receptor Family, Metabotropic Glutamate Receptors, in Cancer Development and Progression

Cancer is the second leading cause of death, and incidences are increasing globally. Simply defined, cancer is the uncontrolled proliferation of a cell, and depending on the tissue of origin, the cancer etiology, biology, progression, prognosis, and treatment will differ. Carcinogenesis and its progression are associated with genetic factors that can either be inherited and/or acquired and are classified as an oncogene or tumor suppressor. Many of these genetic factors converge on common signaling pathway(s), such as the MAPK and PI3K/AKT pathways. In this review, we will focus on the metabotropic glutamate receptor (mGluR) family, an upstream protein that transmits extracellular signals into the cell and has been shown to regulate many aspects of tumor development and progression. We explore the involvement of members of this receptor family in various cancers that include breast cancer, colorectal cancer, glioma, kidney cancer, melanoma, oral cancer, osteosarcoma, pancreatic cancer, prostate cancer, and T-cell cancers. Intriguingly, depending on the member, mGluRs can either be classified as oncogenes or tumor suppressors, although in general most act as an oncogene. The extensive work done to elucidate the role of mGluRs in various cancers suggests that it might be a viable strategy to therapeutically target glutamatergic signaling.

Bioinformatic profiling identifies the glutaminase to be a potential novel cuproptosis-related biomarker for glioma

Glioma is the most common tumour of the central nervous system, with a poor prognosis and an increasing trend of incidence in recent years; it is also beginning to affect younger age groups more. Added to this, cuproptosis is a new form of cell death. Indeed, when a certain amount of copper accumulates in a cell, it affects specific mitochondrial metabolic enzymes in that cell and leads to cell death–a phenomenon known as cuproptosis. In this study, we applied bioinformatics analysis, and, according to the results of the study analysis and Gene Ontology (GO), as well as the Kyoto Encyclopedia of Genes and Genomes KyotoEncyclopediaofGenesandGenomes, the glutaminase (GLS) genes affect the prognosis and tumour mutation of glioma patients through cuproptosis. Interestingly, however, GLS is not involved in the immune escape of glioma. Glutaminase genes are a class of glucose metabolism-related genes that are involved in the tricarboxylic acid cycle of cells. At the same time, the expression of the glutaminase gene was positively correlated with the degree of immune cell infiltration and the expression of various immune cell markers, and thus affected the prognosis of glioma patients. Therefore, we believe that the cuproptosis-related glutaminase gene can be an important factor in determining the prognosis of glioma patients.

Long non-coding RNA IGFBP7-AS1 accelerates the odontogenic differentiation of stem cells from human exfoliated deciduous teeth by regulating IGFBP7 expression

Stem cells from human exfoliated deciduous teeth (SHED) are attractive seed cells for dental tissue engineering. We identified the effect of the long noncoding RNA insulin-like growth factor-binding protein 7 antisense RNA 1 (lncRNA IGFBP7-AS1) in vivo and its underlying mechanism during SHED odontogenic differentiation. IGFBP7-AS1 and insulin-like growth factor-binding protein 7 (IGFBP7) were overexpressed using lentiviruses. IGFBP7 expression was knocked down with small interfering RNA. The effect of IGFBP7-AS1 in vivo was confirmed by animal experiments. The effect of IGFBP7 on SHED odontogenic differentiation was assessed with alkaline phosphatase staining, alizarin red S staining, quantitative reverse transcription-PCR, and western blotting. The relationship between IGFBP7-AS1 and IGFBP7 was confirmed by quantitative reverse transcription–PCR and western blotting. IGFBP7-AS1 promoted SHED odontogenesis in vivo, and regulated the expression of the coding gene IGFBP7 positively. Inhibiting IGFBP7 led to suppress SHED odontogenic differentiation while IGFBP7 overexpression had the opposite effect. IGFBP7-AS1 enhanced the stability of IGFBP7. IGFBP7-AS1 promoted SHED odontogenic differentiation in vivo. The underlying mechanism may involve the enhancement of IGFBP7 stability. This may provide novel potential targets for dental tissue engineering.

Noncoding RNAs as sensors of tumor microenvironmental stress

The tumor microenvironment (TME) has been demonstrated to modulate the biological behavior of tumors intensively. Multiple stress conditions are widely observed in the TME of many cancer types, such as hypoxia, inflammation, and nutrient deprivation. Recently, accumulating evidence demonstrates that the expression levels of noncoding RNAs (ncRNAs) are dramatically altered by TME stress, and the dysregulated ncRNAs can in turn regulate tumor cell proliferation, metastasis, and drug resistance. In this review, we elaborate on the signal transduction pathways or epigenetic pathways by which hypoxia-inducible factors (HIFs), inflammatory factors, and nutrient deprivation in TME regulate ncRNAs, and highlight the pivotal roles of TME stress-related ncRNAs in tumors. This helps to clarify the molecular regulatory networks between TME and ncRNAs, which may provide potential targets for cancer therapy.

ADAR1-Mediated RNA Editing and Its Role in Cancer

It is well known that the stability of RNA, the interaction between RNA and protein, and the correct translation of protein are significant forces that drive the transition from normal cell to malignant tumor. Adenosine deaminase acting on RNA 1 (ADAR1) is an RNA editing enzyme that catalyzes the deamination of adenosine to inosine (A-to-I), which is one dynamic modification that in a combinatorial manner can give rise to a very diverse transcriptome. ADAR1-mediated RNA editing is essential for survival in mammals and its dysregulation results in aberrant editing of its substrates that may affect the phenotypic changes in cancer. This overediting phenomenon occurs in many cancers, such as liver, lung, breast, and esophageal cancers, and promotes tumor progression in most cases. In addition to its editing role, ADAR1 can also play an editing-independent role, although current research on this mechanism is relatively shallowly explored in tumors. In this review, we summarize the nature of ADAR1, mechanisms of ADAR1 editing-dependent and editing-independent and implications for tumorigenesis and prognosis, and pay special attention to effects of ADAR1 on cancers by regulating non-coding RNA formation and function.

Long Noncoding RNA BCYRN1 Recruits BATF to Promote TM4SF1 Upregulation and Enhance HCC Cell Proliferation and Invasion

Hepatocellular carcinoma (HCC) is a common form of cancer for which a subset of reliable clinical biomarkers has been defined. However, other factors including long noncoding RNAs (lncRNAs) can also regulate HCC development. This study was thus designed to understand how the lncRNA Brain cytoplasmic RNA 1 (BCYRN1) modulates HCC progression. Bioinformatics approaches were used to identify genes, lncRNAs, and transcription factors that were differentially expressed in the context of HCC, after which the relative expression of BCYRN1 in HCC and control tissues was assessed via qPCR. The ability of BCYRN1 to bind the transcription factor BATF was further evaluated in an RNA immunoprecipitation (RIP) assay, while chromatin immunoprecipitation (ChIP) was used to gauge the binding of the TM4SF1 promoter by BATF. Luciferase reporter assays were also used to assess the association between BCYRN1 and the TM4SF1 promoter. Subsequent loss- and gain-of-function assays were then conducted to explore the effects of altering BCYRN1 expression levels on the proliferative, invasive, and migratory activity of HCC cells. BCYRN1 upregulation was associated with poorer clinical outcomes in HCC patients, and knocking down this lncRNA impaired HCC cell migration and invasion. From a mechanistic perspective, BATF was recruited to the TM4SF1 promoter by BCYRN1, and reducing the expression of this lncRNA was sufficient to constrain xenograft tumor growth in mice. These results highlight BCYRN1 as a putative therapeutic target in HCC tumors.

Long noncoding RNA TFAP2A-AS1 promotes oral squamous cell carcinoma cell growth and movement via competitively binding miR-1297 and regulating TFAP2A expression

Oral squamous cell carcinoma (OSCC) is an aggressive and common malignancy in the head and neck, characterized by poor prognosis and high incidence. This study aimed to investigate the role of long noncoding RNA TFAP2A-AS1 in OSCC. The competing endogenous RNA network of TFAP2A-AS1 was constructed by bioinformatics analysis. The expressions of miR-1297, TFAP2A-AS1, and TFAP2A were measured by quantitative reverse transcription-polymerase chain reaction. The correlations of TFAP2A-AS1, miR-1297, and TFAP2A with clinicopathological characteristics of OSCC were assessed. RNA immunoprecipitation and dual-luciferase reporter assay were used to identify the target of miR-1297. Cell proliferation was measured by colony formation assay and [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] assay. Transwell assay and wound healing assay were performed to assess cell movement. TFAP2A-AS1 and TFAP2A were upregulated in OSCC and their expression levels were positively correlated. The levels of TFAP2A-AS1, miR-1297, and TFAP2A were also associated with lymphatic metastasis and the tumor-node-metastasis (TNM) stage of OSCC patients. TFAP2A-AS1 acted as a miR-1297 sponge. OSCC cell growth and movement were inhibited by miR-1297. Changes in the miR-1297 expression abolished the effects of TFAP2A-AS1 on OSCC cells. Additionally, TFAP2A was a target of miR-1297. TFAP2A promoted OSCC cell growth and migration/invasion, indicating that TFAP2A mediated the effects of TFAP2A-AS1 and miR-1297. TFAP2A-AS1 exerts an oncogenic effect in OSCC via the TFAP2A-AS1/miR-1297/TFAP2A axis, which may provide new targets and strategies for OSCC treatments.

HIF-1α-mediated augmentation of miRNA-18b-5p facilitates proliferation and metastasis in osteosarcoma through attenuation PHF2

Extensive evidence has explored the involvement of microRNAs (miRNAs) in osteosarcoma (OS). Limitedly, the concrete function of microRNA-18b-5p (miR-18b-5p) in OS remains unexplored and largely elusive. Here, we validated that miR-18b-5p significantly elevated in OS via analyzing the data from GEO database. The results showed that miR-18b-5p was overexpressed in human OS tissues and cell lines. The clinical evidence suggested that high level of miR-18b-5p was negatively correlated with the poor prognosis of OS. Meanwhile, miR-18b-5p upregulation facilitated the proliferation and metastasis of OS cells in vitro and in vivo. The mechanism exploration demonstrated that miR-18b-5p acted as a potential inhibitor of PHF2, a tumor suppressor gene, at post-transcriptional level. Moreover, hypoxia induced gene expression of miR-18b-5p was clarified to be transcriptionally mediated by HIF-1α. The clinicopathological analysis in samples of OS patients further supported that miR-18b-5p had a positive correlation with HIF-1α expression, and negative correlation with PHF2. Collectively, the present study uncovered a new molecular mechanism of OS tumorigenesis and development and miR-18b-5p might be a prognostic biomarker and potential therapeutic target for OS treatment.

Stressing the Regulatory Role of Long Non-Coding RNA in the Cellular Stress Response during Cancer Progression and Therapy

Cellular stress response is an important adaptive mechanism for regulating cell fate decision when cells confront with stress. During tumorigenesis, tumor progression and the course of treatment, cellular stress signaling can activate subsequent response to deal with stress. Therefore, cellular stress response has impacts on the fate of tumor cells and tumor responsiveness relative to therapeutic agents. In recent years, attention has been drawn to long non-coding RNAs (lncRNAs), a novel class of RNA molecules with more than 200 nucleotides in length, which has little protein-coding potential and possesses various functions in multiple biological processes. Accumulating evidence has shown that lncRNAs are also engaged in the regulation of cellular stress response, particularly in cancers. Here, we summarize lncRNAs that have been reported in the adaptive response to major types of cellular stress including genotoxic, hypoxic, oxidative, metabolic and endoplasmic reticulum stress, all of which are often encountered by cancer cells. Specifically, the molecular mechanisms of how lncRNAs regulate cellular stress response during tumor progression or the development of therapy resistance are emphasized. The potential clinical applications of stress-responsive lncRNAs as biomarkers will also be discussed.

The Role of Feedback Loops in Targeted Therapy for Pancreatic Cancer

Pancreatic cancer is the leading cause of cancer-related deaths worldwide, with limited treatment options and low long-term survival rates. The complex and variable signal regulation networks are one of the important reasons why it is difficult for pancreatic cancer to develop precise targeted therapy drugs. Numerous studies have associated feedback loop regulation with the development and therapeutic response of cancers including pancreatic cancer. Therefore, we review researches on the role of feedback loops in the progression of pancreatic cancer, and summarize the connection between feedback loops and several signaling pathways in pancreatic cancer, as well as recent advances in the intervention of feedback loops in pancreatic cancer treatment, highlighting the potential of capitalizing on feedback loops modulation in targeted therapy for pancreatic cancer.

c-Myb-mediated inhibition of miR-601 in facilitating malignance of osteosarcoma via augmentation of PKMYT1

The crosstalk between osteosarcoma (OS) development and abnormally expressed microRNA (miR)-601 is not explored explicitly. Here, we identified the downregulated miR-601 in osteosarcoma (OS) through a comprehensive bioinformatics analysis of GEO Datasets. The results indicated that miR-601 was downregulated in both OS cells and tissues. The OS patients with reduced expression of miR-601 displayed worse prognosis. The results of in vitro and in vivo assay revealed that elevated miR-601 inhibited the proliferative, migratory and invasive capacities in OS cells. Mechanically, miR-601 exerted its function via targeting oncogene protein kinase membrane associated tyrosine/threonine 1 (PKMYT1) at post-transcriptional level. Moreover, miR-601 was attenuated by c-Myb at transcriptional level. Taken together, our studies reveal that miR-601 is a suppressive gene negatively correlated with malignancy of OS.

A reciprocal feedback between N6-methyladenosine reader YTHDF3 and lncRNA DICER1-AS1 promotes glycolysis of pancreatic cancer through inhibiting maturation of miR-5586-5p

Background

Glycolysis is a pivotal process in metabolic reprogramming of tumorigenesis. Previous research has indicated that lncRNAs might play crucial roles in glycolysis of various tumors. However, the function of lncRNAs in glycolysis of pancreatic cancer has not been fully elucidated.

Methods

Bio-information analyses were applied to reveal the potential glycolysis-associated lncRNA. RT-PCR and fluorescence in situ hybridization (FISH) assays were applied to detect the expression of antisense RNA1 of DICER1 (DICER1-AS1) in pancreatic cancer tissues and cell lines. Gain- and loss-of-function experiments were performed to evaluate the roles of DICER1-AS1 in glycolysis and tumorigenesis of PC. Mechanistic experiments including luciferase reporter assay, RNA immunoprecipitation (RIP), and chromatin immunoprecipitation (ChIP) were employed to uncover the downstream targets and regulatory mechanism of DICER1-AS1 in glycolysis of PC.

Results

Bio-information analysis indicated that DICER1-AS1 was downregulated in PC and negatively correlated with glycolytic genes expression. Meanwhile, overexpression of DICER1-AS1 inhibited glycolysis, proliferation, and metastasis of PC cells both in vitro and in vivo. Mechanistically, DICER1-AS1 promoted transcription of its sense gene DICER1 by recruiting transcriptional factor YY1 to the DICER1 promoter. Meanwhile, DICER1 promoted maturation of miR-5586-5p which consequently inhibited glycolytic gene expression including LDHA, HK2, PGK1, and SLC2A1. Notably, enhanced interaction between N6-methyladenosine (m6A) reader YTHDF3 and DICER1-AS1 led to degradation of DICER1-AS1 in response to glucose depletion. Moreover, our data revealed that YTHDF3 was a critical target for miR-5586-5p, by which forming a negative feedback with DICER1-AS1 to regulate glycolysis of PC.

Conclusion

Our results implicate a negative feedback of m6A reader YTHDF3 and glycolytic lncRNA DICER1-AS1 is involved in glycolysis and tumorigenesis of PC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02285-6.

Amino acid restriction induces a long non-coding RNA UBA6-AS1 to regulate GCN2-mediated integrated stress response in breast cancer

Oncogene activation, massive proliferation, and increased nutrient demands often result in nutrient and oxygen deprivation in solid tumors including breast cancer (BC), leading to the induction of oxidative stress and endoplasmic reticulum (ER) stress, and subsequently triggering integrated stress response (ISR). To elucidate the role of long non-coding RNAs (lncRNAs) in the ISR of BC, we performed transcriptome analyses and identified a lncRNA, UBA6-AS1, which was upregulated upon amino acid deprivation and ER stress. UBA6-AS1 was preferentially induced in triple-negative BC (TNBC) cells deprived of arginine or glutamine, two critical amino acids required for cancer cell growth, or treated with ER stress inducers. Mechanistically, UBA6-AS1 was regulated through the GCN2/eIF2α/ATF4 pathway, one of the major routes mediating ISR in amino acid sensing. In addition, both in vitro and in vivo assays indicated that UBA6-AS1 promoted TNBC cell survival when cells encountered metabolic stress, implicating a regulatory role of UBA6-AS1 in response to intratumoral metabolic stress during tumor progression. Moreover, PARP1 expression and activity were positively regulated by the GCN2/UBA6-AS1 axis upon amino acid deprivation. In conclusion, our data suggest that UBA6-AS1 is a novel lncRNA regulating ISR upon metabolic stress induction to promote TNBC cell survival. Furthermore, the GCN2-ATF4 axis is important for UBA6-AS1 induction to enhance PARP1 activity and could serve as a marker for the susceptibility of PARP inhibitors in TNBC.

Targeting glutamine utilization to block metabolic adaptation of tumor cells under the stress of carboxyamidotriazole-induced nutrients unavailability

Tumor cells have unique metabolic programming that is biologically distinct from that of corresponding normal cells. Resetting tumor metabolic programming is a promising strategy to ameliorate drug resistance and improve the tumor microenvironment. Here, we show that carboxyamidotriazole (CAI), an anticancer drug, can function as a metabolic modulator that decreases glucose and lipid metabolism and increases the dependency of colon cancer cells on glutamine metabolism. CAI suppressed glucose and lipid metabolism utilization, causing inhibition of mitochondrial respiratory chain complex I, thus producing reactive oxygen species (ROS). In parallel, activation of the aryl hydrocarbon receptor (AhR) increased glutamine uptake via the transporter SLC1A5, which could activate the ROS-scavenging enzyme glutathione peroxidase. As a result, combined use of inhibitors of GLS/GDH1, CAI could effectively restrict colorectal cancer (CRC) energy metabolism. These data illuminate a new antitumor mechanism of CAI, suggesting a new strategy for CRC metabolic reprogramming treatment.

Interferon-induced protein with tetratricopeptide repeats 1 (IFIT1) accelerates osteoclast formation by regulating signal transducer and activator of transcription 3 (STAT3) signalling

Osteoclasts (OCs), the main cause of bone resorption irregularities, may ultimately cause various bone diseases, including osteoarthritis. The objective of this study was to investigate the effect of interferon-induced protein with tetratricopeptide repeats 1 (IFIT1) on OC formation induced by receptor activator of nuclear factor κB (NF-κB) ligand (RANKL) and to further explore its underlying mechanism. IFIT1 expression in Raw264.7 cells treated with macrophage colony-stimulating factor (M-CSF) and RANKL was determined by qRT-PCR. OC formation was detected using tartrate-resistant acid phosphatase (TRAP) staining. The effect of IFIT1 on STAT3 activation was detected using Western blotting. Additionally, Western blotting was used to measure the change in the expression of OC-specific proteins. IFIT1 was highly expressed in Raw264.7 cells after stimulation with M-CSF and RANKL. IFIT1 overexpression accelerated the formation of OCs, as evidenced by the increased number and size of multinuclear cells, and the upregulation of OC-specific proteins, and activated the STAT3 pathway, by inducing phosphorylation of JAK1 and STAT3. However, silencing of IFIT1 inhibited the formation of OCs and a STAT3 inhibitor Stattic weakened the effects of IFIT1. In conclusion, IFIT1 accelerates the formation of OCs, which is caused by RANKL by STAT3 pathway regulation. This study provides a potential basis for further research and for development of drugs for treating bone resorption-related diseases.

KRAS and MET in non-small-cell lung cancer: two of the new kids on the 'drivers' block

Non-small-cell lung cancer (NSCLC) is a heterogeneous disease, and therapeutic management has advanced to identify various critical oncogenic mutations that promote lung cancer tumorigenesis. Subsequent studies have developed targeted therapies against these oncogenes in the hope of personalized treatment based on the tumor's molecular genomics. This review presents a comprehensive review of the biology, new therapeutic interventions, and resistance patterns of two well-defined subgroups, tumors with KRAS and MET alterations. We also discuss the status of molecular testing practices for these two key oncogenic drivers, considering the progressive introduction of next-generation sequencing (NGS) and RNA sequencing in regular clinical practice.

Positive Reciprocal Feedback of lncRNA ZEB1-AS1 and HIF-1α Contributes to Hypoxia-Promoted Tumorigenesis and Metastasis of Pancreatic Cancer

Background

Many studies have reported the roles of the extracellular hypoxia microenvironment in the tumorigenesis and metastasis of multiple cancers. However, long noncoding RNAs (lncRNAs) that induce cancer oncogenicity and metastasis of pancreatic cancer (PC) under hypoxia conditions remain unclear.

Methods

In PC cells, the expression levels of lncRNAs in different conditions (normoxia or hypoxia) were compared through RNA sequencing (RNA-seq). The effects of the zinc finger E-box-binding homeobox 1 (ZEB1-AS1) antisense lncRNA on PC cells cultured in normoxia/hypoxia medium were measured through gain and loss-of-function experiments. Fluorescence in situ hybridization and luciferase reporter assays in addition to in vivo studies were utilized to explore the adaptive mechanisms of ZEB1-AS1 in the hypoxia-promoted proliferation, migration, and invasion ability of PC cells. Moreover, the level of ZEB1-AS1 and its associated targets or pathways were investigated in both PC and pancreatic normal tissues.

Results

RNA-seq revealed that ZEB1-AS1 was significantly upregulated in PC cells under hypoxia conditions. The ZEB1-AS1 expression level was closely associated with poor prognosis of PC patients. Knockdown of ZEB1-AS1 suppressed the proliferation, migration, and invasion of PC cells in vitro as well as PC xenograft tumor growth in vivo. In PC cells, RNAi-mediated reduction of ZEB1-AS1 inhibited zinc finger E-box-binding homeobox 1 (ZEB1), while ZEB1-AS1 overexpression rescued ZEB1 expression, indicating that ZEB1-AS1 promotes ZEB1 expression. Moreover, hypoxia-inducible factor-1α (HIF-1α)induced the expression of ZEB1-AS1 by binding to the ZEB1-AS1 promoter, which contains a putative hypoxia response element (HRE). Mechanistically, ZEB1-AS1 scaffolded the interaction among HIF-1α, ZEB1, and histone deacetylase 1 (HDAC1), leading to deacetylation-mediated stabilization of HIF-1α. We further revealed that ZEB1 induced the deacetylase capacity of HDAC1 to suppress the acetylation or degradation of HIF-1α, improving HIF-1α assembly. Thus, hypoxia-induced ZEB1-AS1 facilitated ZEB1 transcription and the stability of HIF-1α, which promoted the metastasis of PC cells. Clinically, dysregulated ZEB1 and HIF-1α expression was significantly correlated with histological grade, lymphatic metastasis, and distant metastasis in PC patients.

Conclusions

Our results emphasized that the positive reciprocal loop of HIF-1α/ZEB1-AS1/ZEB1/HDAC1 contributes to hypoxia-promoted oncogenicity and PC metastasis, indicating that it might be a novel therapeutic target for PC.

Long non-coding RNA SNHG22 facilitates hepatocellular carcinoma tumorigenesis and angiogenesis via DNA methylation of microRNA miR-16-5p

Hepatocellular carcinoma (HCC) is considered as a common malignancy worldwide. Considerable evidence has illustrated that abnormally expressed long noncoding RNAs (lncRNAs) are in a close correlation with the initiation and progression of various tumors, including HCC. LncRNA small nucleolar RNA host gene 22 (SNHG22) has been reported to play important roles in tumor initiation, but its role and mechanism are little known in HCC. In our report, we discovered the high level of SNHG22 in HCC tissues and cells, and the high expression of SNHG22 was correlated with unfavorable clinical outcome in HCC patients. Functional assays implied that SNHG22 deficiency suppressed cell proliferation, migration, invasion, and angiogenesis in vitro. Additionally, it was also confirmed that silenced SNHG22 suppressed tumor growth and angiogenesis in vivo. Mechanistic exploration revealed that SNHG22 recruited DNMT1 to miR-16-5p DNA promoter through EZH2 and inhibited miR-16-5p transcription via DNA methylation. Finally, we verified that the suppression of miR-16-5p countervailed the suppressive effect of SNHG22 deficiency on HCC cell proliferation, migration, invasion, and angiogenesis. Conclusively, this study clarified the SNHG22/EZH2/DNMT1/miR-16-5p axis and revealed that SNHG22 could be an underlying biomarker for HCC.

Ferroptosis-related lncRNA pairs to predict the clinical outcome and molecular characteristics of pancreatic ductal adenocarcinoma

Ferroptosis is a form of regulated cell death initiated by oxidative perturbations that can be blocked by iron chelators and lipophilic antioxidants, and ferroptosis may be the silver bullet treatment for multiple cancers, including immunotherapy- and chemotherapy-insensitive cancers such as pancreatic ductal adenocarcinoma (PDAC). Numerous studies have noted that long non-coding RNAs (lncRNAs) regulate the biological behaviour of cancer cells by binding to DNA, RNA and protein. However, few studies have reported the role of lncRNAs in ferroptosis processes and the function of ferroptosis-associated lncRNAs. The primary objective of the present study was to identify ferroptosis-related lncRNAs using bioinformatic approaches combined with experimental validation. The second objective was to construct a prognostic model to predict the overall survival of patients with PDAC. The present study identified ferroptosis-related lncRNAs using a bioinformatic approach and validated them in an independent pancreatic cancer cohort from Fudan University Shanghai Cancer Center. The lncRNA SLCO4A1-AS1 was identified as a novel molecule mediating ferroptosis resistance in vitro. A novel algorithm was used to construct a '0 or 1' matrix-based prognosis model, which showed promising diagnostic accuracy for potential clinical translation (area under the curve = 0.89 for the 2-year survival rate). Notably, molecular subtypes classified by the risk scores of the model did not belong to any previously reported subtypes of PDAC. The immune microenvironment, metabolic activities, mutation landscape and ferroptosis sensitivity were significantly distinct between patients with different risk scores. Sensitivity (IC50) to 30 common anticancer drugs was analysed between patients with different risks, and imatinib and axitinib were found to be potential drugs for the treatment of patients with lower risk scores. Overall, we developed an accurate prognostic model based on the expression patterns of ferroptosis lncRNAs, which may contribute greatly to the evaluation of patient prognosis, molecular characteristics and treatment modalities and could be further translated into clinical applications.

Circular RNA hsa_circ_0006117 Facilitates Pancreatic Cancer Progression by Regulating the miR-96-5p/KRAS/MAPK Signaling Pathway

Circular RNAs (circRNAs) play key roles in many malignant tumors, including pancreatic cancer (PC); however, whether circular RNA hsa_circ_0006117, a newly identified circRNA, has a role in PC has not been investigated. Here, in order to elucidate the role and potential molecular mechanisms of circRNAs, we utilized bioinformatic tolls to screen the differentially expressed circRNAs in PC. Subsequently, circular RNA hsa_circ_0006117 was identified as being highly expressed in PC tissues in a screen of two GEO datasets, which was further verified in PC cell lines and tissues. Then, its molecular characteristics were investigated using methods such as Sanger sequencing and fluorescence in situ hybridization (FISH). Functional experiments subsequently indicated that circular RNA hsa_circ_0006117 facilitated the malignant behaviors of PC cells, prompting that it plays an oncogenic role in PC. Moreover, we found that circular RNA hsa_circ_0006117 exerts its PC-promoting effects via activating the KRAS/mitogen-activated protein kinase (MAPK) signaling pathway. Through bioinformatics exploration and dual-luciferase reporter assays, miR-96-5p was identified as a downstream target of circular RNA hsa_circ_0006117. A series of assays confirmed that circular RNA hsa_circ_0006117 acted as a miR-96-5p sponge, thereby promoting the malignant features of PC in a miR-96-5p/KRAS axis-dependent manner. Taken together, our study indicated, for the first time, that the specifically highly expressed circular RNA hsa_circ_0006117 facilitates PC progression via the modulation of the miR-96-5p/KRAS/MAPK signaling pathway and might be a hopeful therapeutic target for PC.

Long non-coding RNA ILF3-AS1 facilitates hepatocellular carcinoma progression by stabilizing ILF3 mRNA in an m6A-dependent manner

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide. Increasing evidences have demonstrated that ILF3 antisense RNA 1 (ILF3-AS1) acts as an oncogenic long noncoding RNA (lncRNA) in several types of human cancers. However, the expression pattern, functional role and underlying mechanism of ILF3-AS1 in HCC remains largely unclear. Here, we found that ILF3-AS1 expression was significantly elevated in HCC tissues and also associated with prognosis of patients with HCC. Functional assays demonstrated that knockdown of ILF3-AS1 expression resulted in the suppression of proliferation, migration and invasion in HCC cells, whereas overexpression of ILF3-AS1 exerted opposite effects. Additionally, knockdown of IFL3-AS1 attenuated HCC tumorigenesis and metastasis in vivo. Mechanistically, ILF3-AS1 associated with ILF3 mRNA and inhibited its degradation. ILF3-AS1 increased ILF3 m⁶A level via recruiting N⁶-methyladenosine (m⁶A) RNA methyltransferase METTL3. Moreover, IFL3-AS1 enhanced the interaction between ILF3 mRNA and m⁶A reader IGF2BP1. Overall, our study revealed the function and mechanism of ILF3-AS1 in the malignant phenotypes of HCC cells, which provides a novel therapeutic target for HCC.

SMAD4-induced knockdown of the antisense long noncoding RNA BRE-AS contributes to granulosa cell apoptosis

Antisense long noncoding RNAs (AS-lncRNAs), a sub-class of lncRNAs, are transcribed in the opposite direction from their overlapping protein-coding genes and are implicated in various physiological and pathological processes. However, their role in female reproduction remains largely unknown. Here, we report that BRE-AS, an AS-lncRNA transcript from intron 10 of the protein-coding gene BRE, is involved in granulosa cell (GC) apoptosis. Based on our previous RNA sequencing data, we identified 28 AS-lncRNAs as important in the initiation of porcine follicular atresia, with BRE-AS showing the most significant upregulation in early atretic follicles. In this study, gain- and loss-of-function assays demonstrated that BRE-AS induces early apoptosis in GCs. Mechanistically, BRE-AS acts in cis to suppress the expression of BRE, an anti-apoptotic factor, via direct interaction with the pre-mRNA transcript of the latter, inducing increased GC apoptosis. Notably, we also found that BRE-AS was upregulated in SMAD4-silenced GCs. SMAD4 was identified as a transcriptional repressor of BRE-AS because it inhibits BRE-AS expression and BRE-AS-mediated GC apoptosis. In conclusion, we not only identified a novel AS-lncRNA related to the early apoptosis of GCs and initiation of follicular atresia but also described a novel regulatory pathway, SMAD4/BRE-AS/BRE, coordinating GC function and female fertility.

The Role of Non-Coding RNAs in the Regulation of the Proto-Oncogene MYC in Different Types of Cancer

Alterations in the expression level of the MYC gene are often found in the cells of various malignant tumors. Overexpressed MYC has been shown to stimulate the main processes of oncogenesis: uncontrolled growth, unlimited cell divisions, avoidance of apoptosis and immune response, changes in cellular metabolism, genomic instability, metastasis, and angiogenesis. Thus, controlling the expression of MYC is considered as an approach for targeted cancer treatment. Since c-Myc is also a crucial regulator of many cellular processes in healthy cells, it is necessary to find ways for selective regulation of MYC expression in tumor cells. Many recent studies have demonstrated that non-coding RNAs play an important role in the regulation of the transcription and translation of this gene and some RNAs directly interact with the c-Myc protein, affecting its stability. In this review, we summarize current data on the regulation of MYC by various non-coding RNAs that can potentially be targeted in specific tumor types.

Metabolism-related long non-coding RNAs (lncRNAs) as potential biomarkers for predicting risk of recurrence in breast cancer patients

Metabolism affects the development, progression, and prognosis of various cancers, including breast cancer (BC). Our aim was to develop a metabolism-related long non-coding RNA (lncRNA) signature to assess the prognosis of BC patients in order to optimize treatment. Metabolism-related genes between breast tumors and normal tissues were screened out, and Pearson correlation analysis was used to investigate metabolism-related lncRNAs. In total, five metabolism-related lncRNAs were enrolled to establish prognostic signatures. Kaplan-Meier plots and the receiver operating characteristic (ROC) curves demonstrated good performance in both training and validation groups. Further analysis demonstrated that the signature was an independent prognostic factor for BC. A nomogram incorporating risk score and tumor stage was then constructed to evaluate the 3 - and 5-year recurrence-free survival (RFS) in patients with BC. In conclusion, this study identified a metabolism-related lncRNA signature that can predict RFS of BC patients and established a prognostic nomogram that helps guide the individualized treatment of patients at different risks.

Regulation of Metabolic Reprogramming by Long Non-Coding RNAs in Cancer

Metabolic reprogramming is a well described hallmark of cancer. Oncogenic stimuli and the microenvironment shape the metabolic phenotype of cancer cells, causing pathological modifications of carbohydrate, amino acid and lipid metabolism that support the uncontrolled growth and proliferation of cancer cells. Conversely, metabolic alterations in cancer can drive changes in genetic programs affecting cell proliferation and differentiation. In recent years, the role of non-coding RNAs in metabolic reprogramming in cancer has been extensively studied. Here, we review this topic, with a focus on glucose, glutamine, and lipid metabolism and point to some evidence that metabolic alterations occurring in cancer can drive changes in non-coding RNA expression, thus adding an additional level of complexity in the relationship between metabolism and genetic programs in cancer cells.

The emerging regulatory roles of long non-coding RNAs implicated in cancer metabolism

Compared to normal cells, cancer cells exhibit specific metabolic characteristics that facilitate the growth and metastasis of cancer. It is now widely appreciated that long non-coding RNAs (lncRNAs) exert extensive regulatory effects on a spectrum of biological processes through diverse mechanisms. In this review, we focus on the rapidly advancing field of lncRNAs and summarize the relationship between the dysregulation of lncRNAs and cancer metabolism, with a particular emphasis on the specific roles of lncRNAs in glycolysis, mitochondrial function, glutamine, and lipid metabolism. These investigations reveal that lncRNAs are a key factor in the complexity of malignant cancer metabolism. Only through understanding the relevance between lncRNAs and cancer metabolic reprogramming can we open a new chapter in the history of carcinogenesis, one that promises to alter the methods of cancer diagnosis and treatment.

LINC00460 promotes pancreatic cancer progression by sponging miR-491-5p

BACKGROUND

A growing body of studies have suggested that LINC00460 is instrumental in tumorigenesis and tumour progression. Nonetheless, the biological function and mechanisms of LINC00460 in pancreatic ductal adenocarcinoma (PDAC) remain vague.

METHODS

Analysis based on public databases and a quantitative reverse transcription-polymerase chain reaction were performed to screen for differentially expressed lncRNAs in PDAC and to detect LINC00460 expression in PDAC cell lines and clinical samples. The survival of patients in the up-regulated and down-regulated LINC00460 expression groups was compared by using the Kaplan-Meier method. In addition, the potential biological functions of LINC00460 in PDAC were explored by cell counting kit-8, colony formation, flow cytometry and transwell assays. Furthermore, bioinformatics analysis, luciferase reporter assays and rescue experiments were applied to demonstrate the mechanism by which LINC00460 could directly bind to and inhibit miR-491-5p.

RESULTS

LINC00460 is up-regulated in PDAC and correlates with adverse survival outcomes. The results of functional tests verified that LINC00460 knockdown inhibited both cell proliferation and cell migration. Additionally, knockdown led to G0/G1 cell cycle blockage and enhanced cell apoptosis. Mechanistic investigations revealed that LINC00460 directly binds to and attenuates the tumour suppressor miR-491-5p, thus accelerating PDAC progression.

CONCLUSIONS

This research showed that LINC00460 is overexpressed in PDAC and correlates with adverse clinical outcomes. Additionally, LINC00460 promotes the aggressiveness of PDAC by targeting miR-491-5p. Thus, LINC00460 may serve as diagnostic biomarker of PDAC and a new target for PDAC therapy.