Suppression of miR-199a maturation by HuR is crucial for hypoxia-induced glycolytic switch in hepatocellular carcinoma

miR-10b-5p promotes tumor growth by regulating cell metabolism in liver cancer via targeting SLC38A2

Metabolic reprogramming plays a critical role in hepatocarcinogenesis. However, the mechanisms regulating metabolic reprogramming in primary liver cancer (PLC) are unknown. Differentially expressed miRNAs between PLC and normal tissues were identified using bioinformatic analysis. RT-qPCR was used to determine miR-10b-5p and SCL38A2 expression levels. IHC, WB, and TUNEL assays were used to assess the proliferation and apoptosis of the tissues. The proliferation, migration, invasion, and apoptosis of PLC cells were determined using the CCK-8 assay, Transwell assay, and flow cytometry. The interaction between miR-10b-5p and SLC38A2 was determined using dual-luciferase reporter assay. A PLC xenograft model in BALB/c nude mice was established, and tumorigenicity and SLC38A2 expression were estimated. Finally, liquid chromatography - mass spectrometry (LC-MS) untargeted metabolomics was used to analyze the metabolic profiles of xenograft PLC tissues in nude mice. miR-10b-5p was a key molecule in the regulation of PLC. Compared with para-carcinoma tissues, miR-10b-5p expression was increased in tumor tissues. miR-10b-5p facilitated proliferation, migration, and invasion of PLC cells. Mechanistically, miR-10b-5p targeted SLC38A2 to promote PLC tumor growth. Additionally, miR-10b-5p altered the metabolic features of PLC in vivo. Overexpression of miR-10b-5p resulted in remarkably higher amounts of lumichrome, folic acid, octanoylcarnitine, and Beta-Nicotinamide adenine dinucleotide, but lower levels of 2-methylpropanal, glycyl-leucine, and 2-hydroxycaproic acid. miR-10b-5p facilitates the metabolic reprogramming of PLC by targeting SLC38A2, which ultimately boosts the proliferation, migration, and invasion of PLC cells. Therefore, miR-10b-5p and SLC38A2 are potential targets for PLC diagnosis and treatment.

Regulation of Cancer-Associated miRNAs Expression under Hypoxic Conditions

Solid tumors frequently experience hypoxia or low O2 levels. In these conditions, hypoxia-inducible factor 1 alpha (HIF-1α) is activated and acts as a transcription factor that regulates cancer cell adaptation to O2 and nutrient deprivation. HIF-1α controls gene expression associated with various signaling pathways that promote cancer cell proliferation and survival. MicroRNAs (miRNAs) are 22-nucleotide noncoding RNAs that play a role in various biological processes essential for cancer progression. This review presents an overview of how hypoxia regulates the expression of multiple miRNAs in the progression of cancer cells.

Targeting the Warburg effect: A revisited perspective from molecular mechanisms to traditional and innovative therapeutic strategies in cancer

Cancer reprogramming is an important facilitator of cancer development and survival, with tumor cells exhibiting a preference for aerobic glycolysis beyond oxidative phosphorylation, even under sufficient oxygen supply condition. This metabolic alteration, known as the Warburg effect, serves as a significant indicator of malignant tumor transformation. The Warburg effect primarily impacts cancer occurrence by influencing the aerobic glycolysis pathway in cancer cells. Key enzymes involved in this process include glucose transporters (GLUTs), HKs, PFKs, LDHs, and PKM2. Moreover, the expression of transcriptional regulatory factors and proteins, such as FOXM1, p53, NF-κB, HIF1α, and c-Myc, can also influence cancer progression. Furthermore, lncRNAs, miRNAs, and circular RNAs play a vital role in directly regulating the Warburg effect. Additionally, gene mutations, tumor microenvironment remodeling, and immune system interactions are closely associated with the Warburg effect. Notably, the development of drugs targeting the Warburg effect has exhibited promising potential in tumor treatment. This comprehensive review presents novel directions and approaches for the early diagnosis and treatment of cancer patients by conducting in-depth research and summarizing the bright prospects of targeting the Warburg effect in cancer.

[RBMX overexpression inhibits proliferation, migration, invasion and glycolysis of human bladder cancer cells by downregulating PKM2]

OBJECTIVE

To investigate the role of RNA-binding motif protein X-linked (RBMX) in regulating the proliferation, migration, invasion and glycolysis in human bladder cancer cells.

METHODS

A lentivirus vectors system and RNA interference technique were used to construct bladder cancer 1376 and UC-3 cell models with RBMX overexpression and knockdown, respectively, and successful cell modeling was verified using RT-qPCR and Western blotting. Proliferation and colony forming ability of the cells were evaluated using EdU assay and colony-forming assay, and cell migration and invasion abilities were determined using Transwell experiment. The expressions of glycolysis-related proteins M1 pyruvate kinase (PKM1) and M2 pyruvate kinase (PKM2) were detected using Western blotting. The effects of RBMX overexpression and knockdown on glycolysis in the bladder cancer cells were assessed using glucose and lactic acid detection kits.

RESULTS

RT-qPCR and Western blotting confirmed successful construction of 1376 and UC-3 cell models with RBMX overexpression and knockdown. RBMX overexpression significantly inhibited the proliferation, clone formation, migration and invasion of bladder cancer cells, while RBMX knockdown produced the opposite effects. Western blotting results showed that RBMX overexpression increased the expression of PKM1 and decreased the expression of PKM2, while RBMX knockdown produced the opposite effects. Glucose consumption and lactate production levels were significantly lowered in the cells with RBMX overexpression (P < 0.05) but increased significantly following RBMX knockdown (P < 0.05).

CONCLUSION

RBMX overexpression inhibits bladder cancer progression and lowers glycolysis level in bladder cancer cells by downregulating PKM2 expression, suggesting the potential of RBMX as a molecular target for diagnosis and treatment of bladder cancer.

Verteporfin Suppresses YAP-Induced Glycolysis in Breast Cancer Cells

OBJECTIVE

The inhibition of the Hippo pathway through targeting the Yes-associated protein (YAP) presents a novel and promising approach for treating tumors. However, the efficacy of YAP inhibitors in the context of breast cancer (BC) remains incompletely understood. Here, we aimed to investigate the involvement of YAP in BC's metabolic reprogramming and reveal the potential underlying mechanisms. To this end, we assessed the function of verteporfin (VP), a YAP-TEAD complex inhibitor, on the glycolytic activity of BC cells.

METHODS

We evaluated the expression of YAP by utilizing immunohistochemistry (IHC) in BC patients who have undergone 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) prior to biopsy/surgery. We employed RNA immunoprecipitation (RIP) and fluorescent in situ hybridization (FISH) assays to assess the interaction between YAP mRNA and human antigen R (HuR) in BC cells. The biological importance of YAP in the metabolism and malignancy of BC was evaluated in vitro. Finally, the effect of VP on glycolysis was determined by using 18F-FDG uptake, glucose consumption, and lactate production assays.

RESULTS

Our studies revealed that high expression of YAP was positively correlated with the maximum uptake value (SUVmax) determined by 18F-FDG PET/CT imaging in BC samples. Inhibition of YAP activity suppressed glycolysis in BC. The mechanism underlying this phenomenon could be the binding of YAP to HuR, which promotes glycolysis in BC cells. Treatment with VP effectively suppressed glycolysis induced by YAP overexpression in BC cells.

CONCLUSION

VP exhibited anti-glycolytic effect on BC cells, indicating its therapeutic value as an FDA-approved drug.

CircANKRD17 promotes glycolysis by inhibiting miR-143 in breast cancer cells

Glucose metabolic reprogramming, known as the Warburg effect, is one of the metabolic hallmarks of tumor cells. Cancer cells preferentially metabolize glucose by glycolysis rather than mitochondrial oxidative phosphorylation regardless of oxygen availability, but the regulatory mechanism underlying this switch has been incompletely understood. Here, we report that the circular RNA circ ankyrin repeat domain 17 (ANKRD17) functions as a key regulator for glycolysis to promote cell growth, migration, invasion, and cell-cycle progression in breast cancer (BC) cells. We further show that circANKRD17 acts to accelerate glycolysis in BC cells by acting as a sponge for miR-143 and in turn overrides the repressive effect of miR-143, a well-documented glycolytic repressor, on hexokinase 2 in BC cells, thus resulting in enhanced glycolysis in BC cells. These data suggest the circANKRD17-miR-143 cascade as a novel mechanism in controlling glucose metabolic reprogramming in BC cells and suggest circANKRD17 as a promising therapeutic target to interrupt cancerous glycolysis.

miR-17-5p slows progression of hepatocellular carcinoma by downregulating TGFβR2

OBJECTIVE

Downregulation of miR-17-5p has been reported in several cancers, but whether and how miR-17-5p is downregulated in hepatocellular carcinoma (HCC) is unknown. Here, we examined whether miR-17-5p is downregulated in HCC and whether that affects expression of its target gene encoding transforming growth factor β receptor 2 (TGFβR).

METHODS

We screened for potential microRNAs (miRNAs) involved in HCC by analyzing published transcriptomes from HCC patients. Expression of miR-17-5p was measured in HCC cell lines and in tissues from HCC patients using quantitative real-time PCR. The in vitro effects of miR-17-5p on HCC cells were assessed by EdU proliferation assay, CCK-8 cell proliferation assay, colony-formation assay, transwell migration/invasion assay, wound healing assay, and flow cytometry. Effects of miR-17-5p were evaluated in vivo using mice with subcutaneous tumors. Effects of the miRNA on the epithelial-mesenchymal transition (EMT) were assessed, while its effects on TGFβR2 expression were analyzed using bioinformatics and a dual luciferase reporter assay.

RESULTS

Patients with low miR-17-5p expression showed lower rates of overall and recurrence-free survival than patients with high miR-17-5p expression, and multivariate Cox regression identified low miR-17-5p expression as an independent predictor of poor overall survival in HCC patients. In vitro, miR-17-5p significantly inhibited HCC cell proliferation, migration, invasion, and the EMT, while promoting apoptosis. In vivo, it slowed the development of tumors. These protective effects of miR-17-5p were associated with downregulation of TGFβR2.

CONCLUSION

The miRNA miR-17-5p can negatively regulate the expression of TGFβR2 and inhibit the EMT, thereby slowing tumor growth in HCC, suggesting a potential therapeutic approach against HCC.

Recent progress in the immunotherapy of hepatocellular carcinoma: Non-coding RNA-based immunotherapy may improve the outcome

Hepatocellular carcinoma (HCC) is the second most lethal cancer and a leading cause of cancer-related mortality worldwide. Immune checkpoint inhibitors (ICIs) significantly improved the prognosis of HCC; however, the therapeutic response remains unsatisfactory in a substantial proportion of patients or needs to be further improved in responders. Herein, other methods of immunotherapy, including vaccine-based immunotherapy, adoptive cell therapy, cytokine delivery, kynurenine pathway inhibition, and gene delivery, have been adopted in clinical trials. Although the results were not encouraging enough to expedite their marketing. A major proportion of human genome is transcribed into non-coding RNAs (ncRNAs). Preclinical studies have extensively investigated the roles of ncRNAs in different aspects of HCC biology. HCC cells reprogram the expression pattern of numerous ncRNAs to decrease the immunogenicity of HCC, exhaust the cytotoxic and anti-cancer function of CD8 + T cells, natural killer (NK) cells, dendritic cells (DCs), and M1 macrophages, and promote the immunosuppressive function of T Reg cells, M2 macrophages, and myeloid-derived suppressor cells (MDSCs). Mechanistically, cancer cells recruit ncRNAs to interact with immune cells, thereby regulating the expression of immune checkpoints, functional receptors of immune cells, cytotoxic enzymes, and inflammatory and anti-inflammatory cytokines. Interestingly, prediction models based on the tissue expression or even serum levels of ncRNAs could predict response to immunotherapy in HCC. Moreover, ncRNAs markedly potentiated the efficacy of ICIs in murine models of HCC. This review article first discusses recent advances in the immunotherapy of HCC, then dissects the involvement and potential application of ncRNAs in the immunotherapy of HCC.

A critical appraisal of the relative contribution of tissue architecture, genetics, epigenetics and cell metabolism to carcinogenesis

Here we contrast several carcinogenesis models. The somatic-mutation-theory posits mutations as main causes of malignancy. However, inconsistencies led to alternative explanations. For example, the tissue-organization-field-theory considers disrupted tissue-architecture as main cause. Both models can be reconciled using systems-biology-approaches, according to which tumors hover in states of self-organized criticality between order and chaos, are emergent results of multiple deviations and are subject to general laws of nature: inevitable variation(mutation) explainable by increased entropy(second-law-of-thermodynamics) or indeterminate decoherence upon measurement of superposed quantum systems(quantum mechanics), followed by Darwinian-selection. Genomic expression is regulated by epigenetics. Both systems cooperate. So cancer is neither just a mutational nor an epigenetic problem. Rather, epigenetics links environmental cues to endogenous genetics engendering a regulatory machinery that encompasses specific cancer-metabolic-networks. Interestingly, mutations occur at all levels of this machinery (oncogenes/tumor-suppressors, epigenetic-modifiers, structure-genes, metabolic-genes). Therefore, in most cases, DNA mutations may be the initial and crucial cancer-promoting triggers.

A novel microRNA-182/Interleukin-8 regulatory axis controls osteolytic bone metastasis of lung cancer

Bone metastasis is one of the main complications of lung cancer and most important factors that lead to poor life quality and low survival rate in lung cancer patients. However, the regulatory mechanisms underlying lung cancer bone metastasis are still poor understood. Here, we report that microRNA-182 (miR-182) plays a critical role in regulating osteoclastic metastasis of lung cancer cells. We found that miR-182 was significantly upregulated in both bone-metastatic human non-small cell lung cancer (NSCLC) cell line and tumor specimens. We further demonstrated that miR-182 markedly enhanced the ability of NSCLC cells for osteolytic bone metastasis in nude mice. Mechanistically, miR-182 promotes NSCLC cells to secrete Interleukin-8 (IL-8) and in turn facilitates osteoclastogenesis via activating STAT3 signaling in osteoclast progenitor cells. Importantly, systemically delivered IL-8 neutralizing antibody inhibits NSCLC bone metastasis in nude mice. Collectively, our findings identify the miR-182/IL-8/STAT3 axis as a key regulatory pathway in controlling lung cancer cell-induced osteolytic bone metastasis and suggest a promising therapeutic strategy that targets this regulatory axis to interrupt lung cancer bone metastasis.

An Insight into the Arising Role of MicroRNAs in Hepatocellular Carcinoma: Future Diagnostic and Therapeutic Approaches

Hepatocellular carcinoma (HCC) constitutes a frequent highly malignant form of primary liver cancer and is the third cause of death attributable to malignancy. Despite the improvement in the therapeutic strategies with the exploration of novel pharmacological agents, the survival rate for HCC is still low. Shedding light on the multiplex genetic and epigenetic background of HCC, such as on the emerging role of microRNAs, is considered quite promising for the diagnosis and the prediction of this malignancy, as well as for combatting drug resistance. MicroRNAs (miRNAs) constitute small noncoding RNA sequences, which play a key role in the regulation of several signaling and metabolic pathways, as well as of pivotal cellular functions such as autophagy, apoptosis, and cell proliferation. It is also demonstrated that miRNAs are significantly implicated in carcinogenesis, either acting as tumor suppressors or oncomiRs, while aberrations in their expression levels are closely associated with tumor growth and progression, as well as with local invasion and metastatic dissemination. The arising role of miRNAs in HCC is in the spotlight of the current scientific research, aiming at the development of novel therapeutic perspectives. In this review, we will shed light on the emerging role of miRNAs in HCC.

iASPP suppression mediates terminal UPR and improves BRAF-inhibitor sensitivity of colon cancers

Unfolded protein response (UPR) signaling is activated under endoplasmic reticulum (ER) stress, an emerging cancer hallmark, leading to either adaptive survival or cell death, while the mechanisms underlying adaptation-death switch remain poorly understood. Here, we examined whether oncogene iASPP regulates the switch and how the mechanisms can be used in colon cancer treatment. iASPP is downregulated when cells undergo transition from adaptation to death during therapy-induced ER stress. Blocking iASPP's downregulation attenuates stress-induced cell death. Mechanistically, Hu-antigen R (HuR)-mediated stabilization of iASPP mRNA and subsequent iASPP protein production is significantly impaired with prolonged ER stress, which facilitates the degradation of GRP78, a key regulator of the UPR, in the cytosol. Because iASPP competes with GRP78 in binding the ER-resident E3 ligase RNF185, and tips the balance in favor of cell death. Positive correlation between the levels of HuR, iASPP, and GRP78 are detectable in colon cancer tissues in vivo. Genetic inhibition of iASPP/GRP78 or chemical inhibition of HuR not only inhibits tumor growth, but also sensitizes colon cancer cells' responses to BRAF inhibitor-induced ER stress and cell death. This study provides mechanistic insights into the switch between adaptation and death during ER stress, and also identifies a potential strategy to improve BRAF-inhibitor efficiency in colon cancers.

MiR-199a-3p Induces Mesenchymal to Epithelial Transition of Keratinocytes by Targeting RAP2B

Cutaneous squamous cell carcinoma (CSCC) is an epidermal skin cancer that evolves from normal epidermis along several pre-malignant stages. Previously we found specific miRNAs alterations in each step along these stages. miR-199a-3p expression decreases at the transition to later stages. A crucial step for epithelial carcinoma cells to acquire invasive capacity is the disruption of cell-cell contacts and the gain of mesenchymal motile phenotype, a process known as epithelial-to-mesenchymal transition (EMT). This study aims to study the role of decreased expression of miR-199a-3p in keratinocytes' EMT towards carcinogenesis. First, we measured miR-199a-3p in different stages of epidermal carcinogenesis. Then, we applied Photoactivatable Ribonucleoside-Enhanced Crosslinking and Immunoprecipitation (PAR-CLIP) assay to search for possible biochemical targets of miR-199a-3p and verified that Ras-associated protein B2 (RAP2B) is a bona-fide target of miR-199a-3p. Next, we analyzed RAP2B expression, in CSCC biopsies. Last, we evaluated possible mechanisms leading to decreased miR-199a-3p expression. miR-199a-3p induces a mesenchymal to epithelial transition (MET) in CSSC cells. Many of the under-expressed genes in CSCC overexpressing miR-199a-3p, are possible targets of miR-199a-3p and play roles in EMT. RAP2B is a biochemical target of miR-199a-3p. Overexpression of miR-199a-3p in CSCC results in decreased phosphorylated focal adhesion kinase (FAK). In addition, inhibiting FAK phosphorylation inhibits EMT marker genes' expression. In addition, we proved that DNA methylation is part of the mechanism by which miR-199a-3p expression is inhibited. However, it is not by the methylation of miR-199a putative promoter. These findings suggest that miR-199a-3p inhibits the EMT process by targeting RAP2B. Inhibitors of RAP2B or FAK may be effective therapeutic agents for CSCC.

Metabolic reprogramming by miRNAs in the tumor microenvironment: Focused on immunometabolism

MicroRNAs (miRNAs) are emerging as a significant modulator of immunity, and their abnormal expression/activity has been linked to numerous human disorders, such as cancer. It is now known that miRNAs potentially modulate the production of several metabolic processes in tumor-associated immune cells and indirectly via different metabolic enzymes that affect tumor-associated signaling cascades. For instance, Let-7 has been identified as a crucial modulator for the long-lasting survival of CD8+ T cells (naive phenotypes) in cancer by altering their metabolism. Furthermore, in T cells, it has been found that enhancer of zeste homolog 2 (EZH2) expression is controlled via glycolytic metabolism through miRNAs in patients with ovarian cancer. On the other hand, immunometabolism has shown us that cellular metabolic reactions and processes not only generate ATP and biosynthetic intermediates but also modulate the immune system and inflammatory processes. Based on recent studies, new and encouraging approaches to cancer involving the modification of miRNAs in immune cell metabolism are currently being investigated, providing insight into promising targets for therapeutic strategies based on the pivotal role of immunometabolism in cancer. Throughout this overview, we explore and describe the significance of miRNAs in cancer and immune cell metabolism.

MicroRNA-122 overexpression promotes apoptosis and tumor suppressor gene expression induced by microcystin-leucine arginine in mouse liver

Microcystin-leucine arginine (MC-LR), an important hepatoxin, has the effect of promoting hepatocarcinogenesis. MicroRNA-122 (miR-122), an important tumor suppressor in liver, plays an important role in promoting cell apoptosis. Previous studies found that the expression of miR-122 was reduced after MC-LR exposure in liver. In this study, C57BL/6 mice were exposed to saline, negative control agomir, and MC-LR with or without miR-122 agomir transfection. The results indicated that MC-LR promoted the expressions of tumor suppressor genes and decreased the expressions of anti-apoptotic proteins B cell lymphoma-2 (Bcl-2) and Bcl-2-like 2 (Bcl-w), causing hepatocyte apoptosis. Under MC-LR exposure, miR-122 agomir transfection could further increase the expressions of tumor suppressor genes and the release of cytochrome-c (Cyt-c) and decrease the expressions of Bcl-2 and Bcl-w. In conclusion, miR-122 reduction can mitigate MC-LR-induced apoptosis to a certain extent, which in turn, it is likely to have contributed to MC-LR-induced hepatocarcinogenesis.

MicroRNAs, Tristetraprolin Family Members and HuR: A Complex Interplay Controlling Cancer-Related Processes

Simple Summary

AU-rich Element Binding Proteins (AUBPs) represent important post-transcriptional regulators of gene expression by regulating mRNA decay and/or translation. Importantly, AUBPs can interfere with microRNA-dependent regulation by (i) competing with the same binding sites on mRNA targets, (ii) sequestering miRNAs, thereby preventing their binding to their specific targets or (iii) promoting miRNA-dependent regulation. These data highlight a new paradigm where both miRNA and RNA binding proteins form a complex regulatory network involved in physiological and pathological processes. However, this interplay is still poorly considered, and our current models do not integrate this level of complexity, thus potentially giving misleading interpretations regarding the role of these regulators in human cancers. This review summarizes the current knowledge regarding the crosstalks existing between HuR, tristetraprolin family members and microRNA-dependent regulation.

Abstract

MicroRNAs represent the most characterized post-transcriptional regulators of gene expression. Their altered expression importantly contributes to the development of a wide range of metabolic and inflammatory diseases but also cancers. Accordingly, a myriad of studies has suggested novel therapeutic approaches aiming at inhibiting or restoring the expression of miRNAs in human diseases. However, the influence of other trans-acting factors, such as long-noncoding RNAs or RNA-Binding-Proteins, which compete, interfere, or cooperate with miRNAs-dependent functions, indicate that this regulatory mechanism is much more complex than initially thought, thus questioning the current models considering individuals regulators. In this review, we discuss the interplay existing between miRNAs and the AU-Rich Element Binding Proteins (AUBPs), HuR and tristetraprolin family members (TTP, BRF1 and BRF2), which importantly control the fate of mRNA and whose alterations have also been associated with the development of a wide range of chronic disorders and cancers. Deciphering the interplay between these proteins and miRNAs represents an important challenge to fully characterize the post-transcriptional regulation of pro-tumorigenic processes and design new and efficient therapeutic approaches.

Glucometabolic reprogramming: From trigger to therapeutic target in hepatocellular carcinoma

Glucose, the central macronutrient, releases energy as ATP through carbon bond oxidation and supports various physiological functions of living organisms. Hepatocarcinogenesis relies on the bioenergetic advantage conferred by glucometabolic reprogramming. The exploitation of reformed metabolism induces a uniquely inert environment conducive to survival and renders the hepatocellular carcinoma (HCC) cells the extraordinary ability to thrive even in the nutrient-poor tumor microenvironment. The rewired metabolism also confers a defensive barrier which protects the HCC cells from environmental stress and immune surveillance. Additionally, targeted interventions against key players of HCC metabolic and signaling pathways provide promising prospects for tumor therapy. The active search for novel drugs based on innovative mutation targets is warranted in the future for effectively treating advanced HCC and the preoperative downstage. This article aims to review the regulatory mechanisms and therapeutic value of glucometabolic reprogramming on the disease progression of HCC, to gain insights into basic and clinical research.

Hu Antigen R (HuR) Protein Structure, Function and Regulation in Hepatobiliary Tumors

Simple Summary

Hepatobiliary tumors are a group of primary malignancies encompassing the liver, the intra- and extra-hepatic biliary tracts, and the gall bladder. Within the liver, hepatocellular carcinoma (HCC) is the most common type of primary cancer, which is, also, representing the third-most recurrent cause of cancer-associated death and the sixth-most prevalent type of tumor worldwide, nowadays. Although less frequent, cholangiocarcinoma (CCA) is, currently, a fatal cancer with limited therapeutic options. Here, we review the regulatory role of Hu antigen R (HuR), a ubiquitous member of the ELAV/Hu family of RNA-binding proteins (RBPs), in the pathogenesis, progression, and treatment of HCC and CCA. Overall, HuR is proposed as a valuable diagnostic and prognostic marker, as well as a therapeutic target in hepatobiliary cancers. Therefore, novel therapeutic approaches that can selectively modulate HuR function appear to be highly attractive for the clinical management of these types of tumors.

Abstract

Hu antigen R (HuR) is a 36-kDa ubiquitous member of the ELAV/Hu family of RNA-binding proteins (RBPs), which plays an important role as a post-transcriptional regulator of specific RNAs under physiological and pathological conditions, including cancer. Herein, we review HuR protein structure, function, and its regulation, as well as its implications in the pathogenesis, progression, and treatment of hepatobiliary cancers. In particular, we focus on hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA), tumors where the increased cytoplasmic localization of HuR and activity are proposed, as valuable diagnostic and prognostic markers. An overview of the main regulatory axes involving HuR, which are associated with cell proliferation, invasion, metastasis, apoptosis, and autophagy in HCC, is provided. These include the transcriptional, post-transcriptional, and post-translational modulators of HuR function, in addition to HuR target transcripts. Finally, whereas studies addressing the relevance of targeting HuR in CCA are limited, in the past few years, HuR has emerged as a potential therapeutic target in HCC. In fact, the therapeutic efficacy of some pharmacological inhibitors of HuR has been evaluated, in early experimental models of HCC. We, further, discuss the major findings and future perspectives of therapeutic approaches that specifically block HuR interactions, either with post-translational modifiers or cognate transcripts in hepatobiliary cancers.

The role and mechanism of noncoding RNAs in regulation of metabolic reprogramming in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer. Metabolic reprogramming is considered to be an important hallmark of cancer. Emerging studies have demonstrated that noncoding RNAs (ncRNAs) are closely associated with metabolic reprogramming of HCC. NcRNAs can directly regulate the expressions or functions of metabolic enzymes or indirectly regulate the metabolism of HCC cells through some vital signaling pathways. Until now, the mechanisms of HCC development and progression remain largely unclear, and understanding the regulatory mechanism of ncRNAs on metabolic reprogramming of HCC may provide an important basis for breakthrough progress in the treatment of HCC. In this review, we summarize the ncRNAs involved in regulating metabolic reprogramming of HCC. Specifically, the regulatory roles of ncRNAs in glucose, lipid and amino acid metabolism are elaborated. In addition, we discuss the molecular mechanism of ncRNAs in regulation of metabolic reprogramming and possible therapeutic strategies that target the metabolism of cancer cells by modulating the expressions of specific ncRNAs.

H22954, a long non-coding RNA, inhibits glucose uptake in leukemia cells in a GLUT10-dependent manner

OBJECTIVES

To investigate the performance of H22954, a novel long non-coding RNA (lncRNA), in inhibiting glucose uptake in leukemia cells.

METHODS

¹⁸F-FDG uptake, RNA half-life quantitative real-time polymerase chain reaction (qRT-PCR) and luciferase assays were performed to detect the glucose uptake in the condition of leukemia. Microarrays and qRT-PCR analyses were used to identify the related genes or proteins and elucidate the underlying these processes.

RESULTS

H22954, a novel lncRNA, inhibited glucose uptake in leukemia cells. Using bioinformatics and microarray analyses, GLUT10 was identified as a possible target molecule of H22954. H22954 targeted the 3'untranslated region of GLUT10. In the luciferase assay, the luciferase activity of pGL3-GLUT10 was inhibited by H22954. Consistently, H22954 expression levels were inversely correlated with GLUT10 expression in cell lines and acute myeloid leukemia (AML) samples. Conversely, the degradation rate of GLUT10 mRNA was increased after H22954 overexpression. Moreover, glucose uptake was recovered when the GLUT10-interaction sites in H22954 were mutated.

CONCLUSION

The lncRNA H22954 regulated GLUT10 expression to inhibit glucose uptake in leukemia cells. Our findings provide potentially valuable data for designing new targeted strategies based on H22954.

miR-199a-5p Plays a Pivotal Role on Wound Healing via Suppressing VEGFA and ROCK1 in Diabetic Ulcer Foot

Diabetes mellitus (DM) is a growing health problem. As a common complication of DM, diabetic foot ulcer (DFU) results in delayed wound healing and is a leading cause of nontraumatic amputation. miR-199a-5p, a short noncoding RNA, had abnormal expression in DFU wound tissues. The expression of miR-199a-5p was significantly increased in DFU wound tissues, skin tissues of diabetic rats, and high glucose-induced cells. Vascular endothelial growth factor A (VEGFA) and Rho-associated kinase 1 (ROCK1) are directly targets of miR-199a-5p. Inhibiting the expression of miR-199a-5p alleviated the inhibition of VEGFA and ROCK1, thereby rescued impaired proliferation and migration of HG-induced cells, and restored the normal function of the cells to some extent. In diabetic rats, inhibition of miR-199a-5p significantly increased the expression of VEGFA and ROCK1, significantly promoted wound healing, and rescued impaired wound healing. miR-199a-5p and its targets showed therapeutic effect on diabetic wounds.

Roles of Embryonic Lethal Abnormal Vision-Like RNA Binding Proteins in Cancer and Beyond

Embryonic lethal abnormal vision-like (ELAVL) proteins are RNA binding proteins that were originally discovered as indispensable regulators of the development and functioning of the nervous system. Subsequent studies have shown that ELAVL proteins not only exist in the nervous system, but also have regulatory effects in other tissues. ELAVL proteins have attracted attention as potential therapeutic targets because they stabilize multiple mRNAs by binding within the 3′-untranslated region and thus promote the development of tumors, including hepatocellular carcinoma, pancreatic cancer, ovarian cancer, breast cancer, colorectal carcinoma and lung cancer. Previous studies have focused on these important relationships with downstream mRNAs, but emerging studies suggest that ELAVL proteins also interact with non-coding RNAs. In this review, we will summarize the relationship of the ELAVL protein family with mRNA and non-coding RNA and the roles of ELAVL protein family members in a variety of physiological and pathological processes.

The RNA binding protein human antigen R is a gatekeeper of liver homeostasis

BACKGROUND AND AIMS

NAFLD is initiated by steatosis and can progress through fibrosis and cirrhosis to HCC. The RNA binding protein human antigen R (HuR) controls RNAs at the posttranscriptional level; hepatocyte HuR has been implicated in the regulation of diet-induced hepatic steatosis. The present study aimed to understand the role of hepatocyte HuR in NAFLD development and progression to fibrosis and HCC.

APPROACH AND RESULTS

Hepatocyte-specific, HuR-deficient mice and control HuR-sufficient mice were fed either a normal diet or an NAFLD-inducing diet. Hepatic lipid accumulation, inflammation, fibrosis, and HCC development were studied by histology, flow cytometry, quantitative PCR, and RNA sequencing. The liver lipidome was characterized by lipidomics analysis, and the HuR-RNA interactions in the liver were mapped by RNA immunoprecipitation sequencing. Hepatocyte-specific, HuR-deficient mice displayed spontaneous hepatic steatosis and fibrosis predisposition compared to control HuR-sufficient mice. On an NAFLD-inducing diet, hepatocyte-specific HuR deficiency resulted in exacerbated inflammation, fibrosis, and HCC-like tumor development. A multi-omic approach, including lipidomics, transcriptomics, and RNA immunoprecipitation sequencing revealed that HuR orchestrates a protective network of hepatic-metabolic and lipid homeostasis-maintaining pathways. Consistently, HuR-deficient livers accumulated, already at steady state, a triglyceride signature resembling that of NAFLD livers. Moreover, up-regulation of secreted phosphoprotein 1 expression mediated, at least partially, fibrosis development in hepatocyte-specific HuR deficiency on an NAFLD-inducing diet, as shown by experiments using antibody blockade of osteopontin.

CONCLUSIONS

HuR is a gatekeeper of liver homeostasis, preventing NAFLD-related fibrosis and HCC, suggesting that the HuR-dependent network could be exploited therapeutically.

Diagnostic and Prognostic Value of miRNAs after Coronary Artery Bypass Grafting: A Review

MiRNAs are noncoding, 21-24 nucleotide-long RNA particles that control over 60% of genes. MiRNAs affect gene expression through binding to the 3'-untranslated region of messenger RNA (mRNA), thus inhibiting mRNA translation or inducing mRNA degradation. MiRNAs have been associated with various cardiovascular diseases, including heart failure, hypertension, left ventricular hypertrophy, or ischemic heart disease. In addition, miRNA expression alters during coronary artery bypass grafting (CABG) surgery, which could be used to predict perioperative outcomes. CABG is an operation in which complex coronary arteries stenosis is treated by bypassing atherosclerotic lesions with venous or arterial grafts. Despite a very low perioperative mortality rate and excellent long-term survival, CABG is associated with postoperative complications, including reperfusion injury, graft failure, atrial fibrillation and perioperative myocardial infarction. So far, no reliable diagnostic and prognostic tools to predict prognosis after CABG have been developed. Changes in the perioperative miRNA expression levels could improve the diagnosis of post-CABG myocardial infarction and atrial fibrillation and could be used to stratify risk after CABG. Herein, we describe the expression changes of different subtypes of miRNAs during CABG and review the diagnostic and prognostic utility of miRNAs in patients undergoing CABG.

Molecular Imaging of Tumor Microenvironment to Assess the Effects of Locoregional Treatment for Hepatocellular Carcinoma

Liver cancer is one of the leading causes of cancer deaths worldwide. Among all primary liver cancers, hepatocellular carcinoma (HCC) is the most common type, representing 75%‐85% of all primary liver cancer cases. Median survival following diagnosis of HCC is approximately 6 to 20 months due to late diagnosis in its course and few effective treatment options. Interventional therapy with minimal invasiveness is recognized as a promising treatment for HCC. However, due to the heterogeneity of HCC and the complexity of the tumor microenvironment, the long‐term efficacy of treatment for HCC remains a challenge in the clinic. Tumor microenvironment, including factors such as hypoxia, angiogenesis, low extracellular pH, interstitial fluid pressure, aerobic glycolysis, and various immune responses, has emerged as a key contributor to tumor residual and progression after locoregional treatment for HCC. New approaches to noninvasively assess the treatment response and assist in the clinical decision‐making process are therefore urgently needed. Molecular imaging tools enabling such an assessment may significantly advance clinical practice by allowing real‐time optimization of treatment protocols for the individual patient. This review discusses recent advances in the application of molecular imaging technologies for noninvasively assessing changes occurring in the microenvironment of HCC after locoregional treatment.

Hypoxia boosts aerobic glycolysis of carcinoma：a complex process for tumor development

Hypoxia, a common feature in malignant tumors, is mainly caused by insufficient oxygen supply. Hypoxia is closely related to cancer development, affecting cancer invasion and metastasis, energy metabolism and other pathological processes, and is not conducive to cancer treatment and prognosis. Tumor cells exacerbate metabolic abnormalities to adapt to the hypoxic microenvironment, especially to enhance aerobic glycolysis. Glycolysis leads to an acidic microenvironment in cancer tissues, enhancing cancer metastasis, deterioration and drug resistance. Therefore, hypoxia is a therapeutic target that cannot be ignored in cancer treatment. The adaptation of tumor cells to hypoxia is mainly regulated by hypoxia inducible factors (HIFs), and the stability of HIFs is improved under hypoxic conditions. HIFs can promote the glycolysis of tumors by regulating glycolytic enzymes, transporters, and participates in regulating the TCA (tricarboxylic acid) cycle. In addition, HIFs indirectly affect glycolysis through its interaction with non-coding RNAs. Therefore, targeting hypoxia and HIFs are important tumor therapies.

PKM2 Regulates HSP90-Mediated Stability of the IGF-1R Precursor Protein and Promotes Cancer Cell Survival during Hypoxia

Simple Summary

Generally, IGF-1R is overexpressed in most solid tumors, and its expression is significantly associated with poor prognosis in cancer patients. However, IGF-1R gene amplification events are extremely rare in tumors. It is, therefore, necessary to define the mechanism underlying IGR-1R overexpression to elucidate potential therapeutic targets. Our study, specifically, aimed to define the potential mechanisms associated with PKM2 function in regulating IGF-1R protein expression. PKM2 was found to be a non-metabolic protein that regulates HSP90 binding to and stabilizing the precursor IGF-1R protein, thereby promoting the basal level of mature IGF-1R protein. Consequently, PKM2 knockdown inhibits the activation of AKT, a downstream effector of IGF-1R signaling, and increases apoptosis during hypoxia. Our findings reveal a novel mechanism for regulating IGF-1R protein expression, thus suggesting PKM2 as a potential therapeutic target in cancers associated with aberrant IGF signaling.

Abstract

Insulin-like growth factor-1 receptor (IGF-1R), an important factor in promoting cancer cell growth and survival, is commonly upregulated in cancer cells. However, amplification of the IGF1R gene is extremely rare in tumors. Here, we have provided insights into the mechanisms underlying the regulation of IGF-1R protein expression. We found that PKM2 serves as a non-metabolic protein that binds to and increases IGF-1R protein expression by promoting the interaction between IGF-1R and heat-shock protein 90 (HSP90). PKM2 depletion decreases HSP90 binding to IGF-1R precursor, thereby reducing IGF-1R precursor stability and the basal level of mature IGF-1R. Consequently, PKM2 knockdown inhibits the activation of AKT, the key downstream effector of IGF-1R signaling, and increases apoptotic cancer cell death during hypoxia. Notably, we clinically verified the PKM2-regulated expression of IGF-1R through immunohistochemical staining in a tissue microarray of 112 lung cancer patients, demonstrating a significant positive correlation (r = 0.5208, p < 0.0001) between PKM2 and IGF-1R expression. Together, the results of a previous report demonstrated that AKT mediates PKM2 phosphorylation at serine-202; these results suggest that IGF-1R signaling and PKM2 mutually regulate each other to facilitate cell growth and survival, particularly under hypoxic conditions, in solid tumors with dysregulated IGF-1R expression.

Two MicroRNAs, miR-34a and miR-125a, Are Implicated in Bicuspid Aortopathy by Modulating Metalloproteinase 2

It has been recognized that wall shear stress plays an important role in the development of Bicuspid Aortopathy (BA), but the intrinsic mechanism is not well elucidated. This study aims to explore the underlying relationship between hemodynamical forces and pathological phenomenon. Total RNA was prepared from aortic wall tissues collected from 20 BA patients. RNA sequencing, bioinformatic analysis and quantitative reverse-transcription PCR validation identified nine miRNAs that were up-regulated in the aortic part exposed to high wall shear stress compared to the low wall shear stress control, and six miRNAs that were down-regulated. Among these candidates, miR-34a and miR-125a, both down-regulated in the high wall shear stress parts, were shown to be potential inhibitors of the metalloproteinase 2 gene. Luciferase reporter assays confirmed that both miRNAs could inhibit the expression of metalloproteinase 2 mRNA in CRL1999 by complementing with its 3' untranslated region. Conversely, immunofluorescence assays showed that inhibition of miR-34a or miR-125a could lead to increased metalloproteinase 2 protein level. On the other hand, both miR-34a and miR-125a were shown to alleviate stretch-induced stimulation of metalloproteinase 2 expression in CRL1999 cells. The results suggested that miR-34a and miR-125a might be implicated in wall shear stress induced aortic pathogenesis due to their apparent regulatory roles in metalloproteinase 2 expression and extracellular matrix remodeling, which are key events in the weakening of aortic walls among BA patients.

MicroRNAs as Modulators of Tumor Metabolism, Microenvironment, and Immune Response in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related mortality. Molecular heterogeneity and absence of biomarkers helping patient allocation to the best therapeutic option contribute to poor prognosis in advanced stages. MicroRNAs’ (miRNAs) deregulated expression contributes to tumor development and progression and influences drug resistance in HCC. Accordingly, miRNAs have been extensively investigated as both biomarkers and therapeutic targets. The diagnostic and prognostic roles of circulating miRNAs have been ascertained, though with some inconsistencies across studies. From a therapeutic perspective, miRNA-based approaches demonstrated safety profiles and antitumor efficacy in HCC animal models. Nevertheless, caution should be used when transferring preclinical findings to the clinic, due to possible molecular inconsistency between animal models and the heterogeneous patterns of human diseases. A wealth of information is offered by preclinical studies exploring the mechanisms driving miRNAs’ aberrant expression, the molecular cascades triggered by miRNAs and the corresponding phenotypic changes. Ex-vivo analyses confirmed these results, further shedding light on the intricacy of the human disease often overcoming pre-clinical models. This complexity seems to be ascribed to the intrinsic heterogeneity of HCC, to different risk factors driving its development, as well as to changes across stages and previous treatments. Preliminary findings suggest that miRNAs associated with specific risk factors might be more informative in defined patients’ subgroups. The first issue to be considered when trying to envisage a possible translational perspective is the molecular context that often drives different miRNA functions, as clearly evidenced by “dual” miRNAs. Concerning the possible roles of miRNAs as biomarkers and therapeutic targets, we will focus on miRNAs’ involvement in metabolic pathways and in the modulation of tumor microenvironment, to support their exploitation in defined contexts.

MicroRNA-183-5p contributes to malignant progression through targeting PDCD4 in human hepatocellular carcinoma

Hepatocellular carcinoma (HCC) remains one of the most common malignant tumors worldwide. The present study aimed to investigate the biological role of microRNA-183-5p (miR-183-5p), a novel tumor-related microRNA (miRNA), in HCC and illuminate the possible molecular mechanisms. The expression patterns of miR-183-5p in clinical samples were characterized using qPCR analysis. Kaplan–Meier survival curve was applied to evaluate the correlation between miR-183-5p expression and overall survival of HCC patients. Effects of miR-183-5p knockdown on HCC cell proliferation, apoptosis, migration and invasion capabilities were determined via Cell Counting Kit-8 (CCK8) assays, flow cytometry, scratch wound healing assays and Transwell invasion assays, respectively. Mouse neoplasm transplantation models were established to assess the effects of miR-183-5p knockdown on tumor growth in vivo. Bioinformatics analysis, dual-luciferase reporter assays and rescue assays were performed for mechanistic researches. Results showed that miR-183-5p was highly expressed in tumorous tissues compared with adjacent normal tissues. Elevated miR-183-5p expression correlated with shorter overall survival of HCC patients. Moreover, miR-183-5p knockdown significantly suppressed proliferation, survival, migration and invasion of HCC cells compared with negative control treatment. Consistently, miR-183-5p knockdown restrained tumor growth in vivo. Furthermore, programmed cell death factor 4 (PDCD4) was identified as a direct target of miR-183-5p. Additionally, PDCD4 down-regulation was observed to abrogate the inhibitory effects of miR-183-5p knockdown on malignant phenotypes of HCC cells. Collectively, our data suggest that miR-183-5p may exert an oncogenic role in HCC through directly targeting PDCD4. The current study may offer some new insights into understanding the role of miR-183-5p in HCC.

RBMX suppresses tumorigenicity and progression of bladder cancer by interacting with the hnRNP A1 protein to regulate PKM alternative splicing

The prognosis for patients with metastatic bladder cancer (BCa) is poor, and it is not improved by current treatments. RNA-binding motif protein X-linked (RBMX) are involved in the regulation of the malignant progression of various tumors. However, the role of RBMX in BCa tumorigenicity and progression remains unclear. In this study, we found that RBMX was significantly downregulated in BCa tissues, especially in muscle-invasive BCa tissues. RBMX expression was negatively correlated with tumor stage, histological grade and poor patient prognosis. Functional assays demonstrated that RBMX inhibited BCa cell proliferation, colony formation, migration, and invasion in vitro and suppressed tumor growth and metastasis in vivo. Mechanistic investigations revealed that hnRNP A1 was an RBMX-binding protein. RBMX competitively inhibited the combination of the RGG motif in hnRNP A1 and the sequences flanking PKM exon 9, leading to the formation of lower PKM2 and higher PKM1 levels, which attenuated the tumorigenicity and progression of BCa. Moreover, RBMX inhibited aerobic glycolysis through hnRNP A1-dependent PKM alternative splicing and counteracted the PKM2 overexpression-induced aggressive phenotype of the BCa cells. In conclusion, our findings indicate that RBMX suppresses BCa tumorigenicity and progression via an hnRNP A1-mediated PKM alternative splicing mechanism. RBMX may serve as a novel prognostic biomarker for clinical intervention in BCa.

Non-coding RNAs: emerging regulators of glucose metabolism in hepatocellular carcinoma

Reprogramming of metabolism is one of the hallmarks of cancer, among which glucose metabolism dysfunction is the most prominent feature. The glucose metabolism of tumor cells is significantly different from that of normal cells. Glucose metabolism reprogramming of hepatocellular carcinoma (HCC) has become an important research hotspot in the field of HCC, a variety of tumor metabolic interventions have been applied clinically. Moreover, various Non-coding RNAs (ncRNAs) including microRNAs (miRNAs), long non-coding (lncRNAs) as well as circular RNAs (circRNAs), have recently been proved to play potential roles in glucose metabolism. This review summarizes the effects of ncRNAs on HCC that participate in glucose metabolism and discuss the related mechanisms to find potential and effective targeted treatments for HCC.

Reprogramming Oxidative Phosphorylation in Cancer: A Role for RNA-Binding Proteins

Significance: Cancer is a major disease imposing high personal and economic burden draining large part of National Health Care and Research budgets worldwide. In the last decade, research in cancer has underscored the reprogramming of metabolism to an enhanced aerobic glycolysis as a major trait of the cancer phenotype with great potential for targeted therapy. Recent Advances: Mitochondria are essential organelles in metabolic reprogramming for controlling the production of biological energy through oxidative phosphorylation (OXPHOS) and the supply of metabolic precursors that sustain proliferation. In addition, mitochondria are critical hubs that integrate different signaling pathways that control cellular metabolism and cell fate. The mitochondrial ATP synthase plays a fundamental role in OXPHOS and cellular signaling. Critical Issues: This review overviews mitochondrial metabolism and OXPHOS, and the major changes reported in the expression and function of mitochondrial proteins of OXPHOS in oncogenesis and in cellular differentiation. We summarize the prominent role that RNA-binding proteins (RNABPs) play in the sorting and localized translation of nuclear-encoded mRNAs that help define the mitochondrial cell-type-specific phenotype. Moreover, we emphasize the mechanisms that contribute to restrain the activity and expression of the mitochondrial ATP synthase in carcinomas, and illustrate that the dysregulation of proteins that control energy metabolism correlates with patients' survival. Future Directions: Future research should elucidate the mechanisms and RNABPs that promote the specific alterations of the mitochondrial phenotype in carcinomas arising from different tissues with the final aim of developing new therapeutic strategies to treat cancer.

mRNA Post-Transcriptional Regulation by AU-Rich Element-Binding Proteins in Liver Inflammation and Cancer

AU-rich element-binding proteins (AUBPs) represent important post-transcriptional regulators of gene expression. AUBPs can bind to the AU-rich elements present in the 3'-UTR of more than 8% of all mRNAs and are thereby able to control the stability and/or translation of numerous target mRNAs. The regulation of the stability and the translation of mRNA transcripts by AUBPs are highly complex processes that occur through multiple mechanisms depending on the cell type and the cellular context. While AUBPs have been shown to be involved in inflammatory processes and the development of various cancers, their important role and function in the development of chronic metabolic and inflammatory fatty liver diseases (FLDs), as well as in the progression of these disorders toward cancers such as hepatocellular carcinoma (HCC), has recently started to emerge. Alterations of either the expression or activity of AUBPs are indeed significantly associated with FLDs and HCC, and accumulating evidence indicates that several AUBPs are deeply involved in a significant number of cellular processes governing hepatic metabolic disorders, inflammation, fibrosis, and carcinogenesis. Herein, we discuss our current knowledge of the roles and functions of AUBPs in liver diseases and cancer. The relevance of AUBPs as potential biomarkers for different stages of FLD and HCC, or as therapeutic targets for these diseases, are also highlighted.

PHB regulates meiotic recombination via JAK2-mediated histone modifications in spermatogenesis

Previously, we have shown that human sperm Prohibitin (PHB) expression is significantly negatively correlated with mitochondrial ROS levels but positively correlated with mitochondrial membrane potential and motility. However, the possible role of PHB in mammalian spermatogenesis has not been investigated. Here we document the presence of PHB in spermatocytes and its functional roles in meiosis by generating the first male germ cell-specific Phb-cKO mouse. Loss of PHB in spermatocytes resulted in complete male infertility, associated with not only meiotic pachytene arrest with accompanying apoptosis, but also apoptosis resulting from mitochondrial morphology and function impairment. Our mechanistic studies show that PHB in spermatocytes regulates the expression of STAG3, a key component of the meiotic cohesin complex, via a non-canonical JAK/STAT pathway, and consequently promotes meiotic DSB repair and homologous recombination. Furthermore, the PHB/JAK2 axis was found as a novel mechanism in the maintenance of stabilization of meiotic STAG3 cohesin complex and the modulation of heterochromatin formation in spermatocytes during meiosis. The observed JAK2-mediated epigenetic changes in histone modifications, reflected in a reduction of histone 3 tyrosine 41 phosphorylation (H3Y41ph) and a retention of H3K9me3 at the Stag3 locus, could be responsible for Stag3 dysregulation in spermatocytes with the loss of PHB.

Exosomal CircGDI2 Suppresses Oral Squamous Cell Carcinoma Progression Through the Regulation of MiR-424-5p/SCAI Axis

Background

Exosomes are small membrane vesicles that are secreted by most cell types. Circular RNAs (circRNAs) have recently been identified in exosomes, and exosomal circRNAs exert important biological activities in human cancers, including oral squamous cell carcinoma (OSCC). The purpose of this study was to investigate whether circRNA GDP dissociation inhibitor 2 (circGDI2) was transferred by exosomes and how exosomal circGDI2 regulated OSCC cell malignant behaviors.

Methods

The levels of circGDI2, miR-424-5p and suppressor of cancer cell invasion (SCAI) were detected by quantitative real-time polymerase chain reaction (qRT-PCR) or Western blot. Cell proliferation was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Transwell assays were performed to detect cell migration and invasion. Measurement of glucose consumption and lactate production were conducted using a corresponding assay kit. Targeted correlations among circGDI2, miR-424-5p and SCAI were confirmed by dual-luciferase reporter assays. Xenograft assays were used to observe the role of circGDI2 in tumor growth in vivo.

Results

Our data indicated that circGDI2 was down-regulated in OSCC, and it could be transferred by the exosomes in OSCC cells. The up-regulation of exosomal circGDI2 weakened OSCC cell proliferation, migration, invasion and glycolysis. CircGDI2 functioned as a molecular sponge of miR-424-5p, and SCAI was a direct target of miR-424-5p. MiR-424-5p mediated the repression of exosomal circGDI2 overexpression on OSCC cell malignant behaviors, and miR-424-5p silencing mitigated OSCC cell progression by up-regulating SCAI. Moreover, exosomal circGDI2 regulated SCAI expression through sponging miR-424-5p. Additionally, the overexpression of exosomal circGDI2 inhibited tumor growth in vivo.

Conclusion

The present study had led to the identification of exosomal circGDI2 that regulated OSCC cell malignant behaviors through targeting the miR-424-5p/SCAI axis, highlighting circGDI2 as a novel exosome-based cancer biomarker and therapeutic agent for OSCC treatment.

Role of microRNA-122 in microcystin-leucine arginine-induced dysregulation of hepatic iron homeostasis in mice

Microcystin-leucine arginine (MC-LR) is a cyclic heptapeptide hepatotoxin produced by cyanobacteria. MicroRNA-122 (miR-122) is specifically expressed in the liver. This study focuses on the role of miR-122 in MC-LR-induced dysregulation of hepatic iron homeostasis in C57BL/6 mice. The thirty mice were randomly divided into five groups (Control, 12.5 μg/kg·BW MC-LR, 25 μg/kg·BW MC-LR, Negative control agomir and 25 μg/kg·BW MC-LR + miR-122 agomir). The results show that MC-LR decreases the expressions of miR-122, Hamp, and its related regulators, while increasing the content of hepatic iron and the expressions of FPN1 and Tmprss6. Furthermore, miR-122 agomir pretreatment improves MC-LR induced dysregulation of hepatic iron homeostasis by arousing the related regulators and reducing the expression of Tmprss6. These results suggest that miR-122 agomir can prevent the accumulation of hepatic iron induced by MC-LR, which may be related to the regulation of hepcidin by BMP/SMAD and IL-6/STAT signaling pathways.

Non-coding RNAs, metabolic stress and adaptive mechanisms in cancer

Metabolic reprogramming in cancer describes the multifaceted alterations in metabolism that contribute to tumorigenesis. Major determinants of metabolic phenotypes are the changes in signalling pathways associated with oncogenic activation together with cues from the tumor microenvironment. Therein, depleted oxygen and nutrient levels elicit metabolic stress, requiring cancer cells to engage adaptive mechanisms. Non-coding RNAs (ncRNAs) act as regulatory elements within metabolic pathways and their widespread dysregulation in cancer contributes to altered metabolic phenotypes. Indeed, ncRNAs are the regulatory accomplices of many prominent effectors of metabolic reprogramming including c-MYC and HIFs that are activated by metabolic stress. By example, this review illustrates the range of ncRNAs mechanisms impacting these effectors throughout their DNA-RNA-protein lifecycle along with presenting the mechanistic roles of ncRNAs in adaptive responses to glucose, glutamine and lipid deprivation. We also discuss the facultative activation of metabolic enzymes by ncRNAs, a phenomenon which may reflect a broad but currently invisible level of metabolic regulation. Finally, the translational challenges associated with ncRNA discoveries are discussed, emphasizing the gaps in knowledge together with importance of understanding the molecular basis of ncRNA regulatory mechanisms.

Emerging roles and the regulation of aerobic glycolysis in hepatocellular carcinoma

Liver cancer has become the sixth most diagnosed cancer and the fourth leading cause of cancer death worldwide. Hepatocellular carcinoma (HCC) is responsible for up to 75–85% of primary liver cancers, and sorafenib is the first targeted drug for advanced HCC treatment. However, sorafenib resistance is common because of the resultant enhancement of aerobic glycolysis and other molecular mechanisms. Aerobic glycolysis was firstly found in HCC, acts as a hallmark of liver cancer and is responsible for the regulation of proliferation, immune evasion, invasion, metastasis, angiogenesis, and drug resistance in HCC. The three rate-limiting enzymes in the glycolytic pathway, including hexokinase 2 (HK2), phosphofructokinase 1 (PFK1), and pyruvate kinases type M2 (PKM2) play an important role in the regulation of aerobic glycolysis in HCC and can be regulated by many mechanisms, such as the AMPK, PI3K/Akt pathway, HIF-1α, c-Myc and noncoding RNAs. Because of the importance of aerobic glycolysis in the progression of HCC, targeting key factors in its pathway such as the inhibition of HK2, PFK or PKM2, represent potential new therapeutic approaches for the treatment of HCC.

MicroRNA-130a targeting hypoxia-inducible factor 1 alpha suppresses cell metastasis and Warburg effect of NSCLC cells under hypoxia

MicroRNAs have been demonstrated to play critical role in the development of non-small cell lung cancer (NSCLC) and hypoxia is a common hallmark of NSCLC. MiRNA-130a-3p (miR-130a) is a well-known tumor suppressor, and we intended to explore the role and mechanism of miR-130a in NSCLC cells under hypoxia. We used real-time quantitative polymerase chain reaction method to measure miR-130a expression, and found that miR-130a was downregulated in human NSCLC tumors and cell lines (A549 and H1299), accompanied with upregulation of hypoxia-inducible factor 1 alpha (HIF1A), a marker of hypoxia. Besides, miR-130a low expression was associated with tumor burden and poor overall survival. Moreover, miR-130a expression was even downregulated in hypoxia-treated A549 and H1299 cells. Ectopic expression of miR-130a suppressed Warburg effect, migration and invasion in hypoxic A549 and H1299 cells, as evidenced by decreased glucose consumption, lactate production, hexokinase 2 expression, and numbers of migration cells and invasion cells analyzed by commercial glucose and lactate assay kits, western blotting and transwell assays. Furthermore, overexpression of miR-130a restrained xenograft tumor growth of A549 cells in mice. However, recovery of HIF1A could reverse the suppressive effect of miR-130a overexpression on cell migration, invasion and Warburg effect in hypoxic A549 and H1299 cells. Mechanically, dual-luciferase reporter assay, RNA immunoprecipitation and RNA pull-down assay confirmed a target relationship between miR-130a and HIF1A. Collectively, we demonstrated an anti-tumor role of miR-130a in NSCLC cells under hypoxia through targeting HIF1A, suggesting a potential target for the interfering of NSCLC.

piRNA-independent function of PIWIL1 as a co-activator for anaphase promoting complex/cyclosome to drive pancreatic cancer metastasis

Piwi proteins are normally restricted in germ cells to suppress transposons through associations with Piwi-interacting RNAs (piRNAs), but they are also frequently activated in many types of human cancers. A great puzzle is the lack of significant induction of corresponding piRNAs in cancer cells, as we document here in human pancreatic ductal adenocarcinomas (PDACs), which implies that such germline-specific proteins are somehow hijacked to promote tumorigenesis through a different mode of action. Here, we show that in the absence of piRNAs, human PIWIL1 in PDAC functions as an oncoprotein by activating the anaphase promoting complex/cyclosome (APC/C) E3 complex, which then targets a critical cell adhesion-related protein, Pinin, to enhance PDAC metastasis. This is in contrast to piRNA-dependent PIWIL1 ubiquitination and removal by APC/C during late spermiogenesis. These findings unveil a piRNA-dependent mechanism to switch PIWIL1 from a substrate in spermatids to a co-activator of APC/C in human cancer cells.

Pyruvate Kinase M2 and Cancer: The Role of PKM2 in Promoting Tumorigenesis

Pyruvate kinase plays a pivotal role in regulating cell metabolism. The final and rate-limiting step of glycolysis is the conversion of Phosphoenolpyruvate (PEP) to Pyruvate, which is catalyzed by Pyruvate Kinase. There are four isomeric, tissue-specific forms of Pyruvate Kinase found in mammals: PKL, PKR, PKM1, and PKM2. PKM1 and PKM2 are formed bya single mRNA transcript of the PKM gene by alternative splicing. The oligomers of PKM2 exist in high activity tetramer and low activity dimer forms. The dimer PKM2 regulates the rate-limiting step of glycolysis that shifts the glucose metabolism from the normal respiratory chain to lactate production in tumor cells. Besides its role as a metabolic regulator, it also acts as protein kinase, which contributes to tumorigenesis. This review is focused on the metabolic role of pyruvate kinase M2 in normal cells vs. cancerous cells and its regulation at the transcriptional level. The review also highlights the role of PKM2 as a potential diagnostic marker and as a therapeutic target in cancer treatment.

AZD3463, an IGF-1R inhibitor, suppresses breast cancer metastasis to bone via modulation of the PI3K-Akt pathway

Background

The bone-derived insulin-like growth factor I (IGF-1) and its receptor IGF-1R play a crucial role in promoting the survival and proliferation of cancer cells, and have thus been considered as prime targets for the development of novel antitumor therapeutics.

Methods

By using the MDA-MB-231BO cell line, which is the osteotropic metastatic variant of the human breast adenocarcinoma cell line MDA-MB-231, and an in vivo model of breast cancer metastasis to bone, the current study evaluated the effect of AZD3463, an IGF-1R inhibitor, used alone or in combination with zoledronic acid (ZA), on the regulation of IGF-1R associated signal pathway and treatment of bone metastases (BM). Cell proliferation and invasion were measured by methyl thiazolyl tetrazolium (MTT) and Transwell assay respectively. Apoptotic cell number was detected by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL).

Results

AZD3463 was shown to alleviate IGF-1R phosphorylation promoted by IGF-1 treatment in MDA-MB-231BO cells in a dose-dependent manner. In both the cells and the mouse model, 5 nM of AZD3463 stimulated cell apoptosis and suppressed proliferation on a level similar to that of 100 µM of ZA. Remarkably, the combined use of AZD3463 and ZA exhibited a synergistic effect and greater antitumor activity compared to when they were employed individually. Mechanistic investigations indicated that the apoptosis-inducing activity of AZD3463 could be associated to its role in the activation of the phosphoinositide 3-kinase (PI3K)-Akt signaling pathway.

Conclusions

These findings suggested that AZD3463 could serve as a promising therapeutic molecule for treating BM in breast cancer patients, particularly when applied in conjunction with ZA or other antitumor agents.

Human antigen R: A potential therapeutic target for liver diseases

Human antigen R (HuR), also known as HuA and embryonic lethal abnormal vision-like 1 (ELAVL1), is a ubiquitously expressed RNA binding protein and functions as an RNA regulator and mediates the expression of various proteins by diverse post-transcriptional mechanisms. HuR has been well characterized in the inflammatory responses and in the development of various cancers. The importance of HuR-mediated roles in cell signaling, inflammation, fibrogenesis and cancer development in the liver has attracted a great deal of attention. However, there is still a substantial gap between the current understanding of the potential roles of HuR in the progression of liver disease and whether HuR can be targeted for the treatment of liver diseases. In this review, we introduce the function and mechanistic characterization of HuR, and then focus on the physiopathological roles of HuR in the development of different liver diseases, including hepatic inflammation, alcoholic liver diseases, non-alcoholic fatty liver diseases, viral hepatitis, liver fibrosis and liver cancers. We also summarize existing approaches targeting HuR function. In conclusion, although characterizing the liver-specific HuR function and demonstrating the multi-level regulative networks of HuR in the liver are still required, emerging evidence supports the notion that HuR represents a potential therapeutic target for the treatment of chronic liver diseases.

miR-202 functions as a tumor suppressor in hepatocellular carcinoma by targeting HK2

Recent evidence has suggested that microRNAs (miRNAs) can participate in metabolic reprogramming. Additionally, aerobic glycolysis is associated with tumor progression in hepatocellular carcinoma (HCC). In the present study, miRNA (miR)-202 expression levels were found to be significantly lower in HCC tissues compared with the corresponding adjacent non-cancerous tissue samples using reverse transcription-quantitative PCR analysis in 56 patients with HCC. Lower miR-202 expression levels were identified to be associated with tumor size, vascular invasion, Tumor, Node and Metastasis stages and poor overall survival rates in patients with HCC. In vitro, upregulation of miR-202 expression was revealed to significantly suppress the cell glucose uptake, lactate production and cell proliferation in liver cancer cells. In addition, dual luciferase reporter analysis and western blot assays suggested that hexokinase 2 (HK2) was a direct target of miR-202. Upregulation of miR-202 expression could inhibit cell proliferation by regulating HK2 expression in HCC. Therefore, the results from the present study suggested that miR-202 may serve as a potential target for HCC treatment.

Metformin attenuates hepatoma cell proliferation by decreasing glycolytic flux through the HIF-1α/PFKFB3/PFK1 pathway

AIMS

Enhanced aerobic glycolysis is an essential hallmark of malignant cancer. Blocking the glycolytic pathway has been suggested as a therapeutic strategy to impair the proliferation of tumor cells. Metformin, a widely used anti-diabetes drug, exhibits anti-tumor properties. However, the underlying molecular mechanism of its action linking glucose metabolism with the suppression of proliferation has not been fully clarified.

MAIN METHODS

Stable isotope tracing technology and gas chromatography-mass spectrometry method were utilized to analyze the effect of metformin on glycolytic flux in HCC cells. Western blot and immunohistochemistry were utilized to analyze the expression of phosphofructokinase-1 (PFK1) and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) in HCC cells or xenograft tumor tissues. Lactate measurement and glucose uptake assay were used to analyze the level of lactate and glucose in the presence of frucose-2,6-diphosphate (F2,6BP) in HCC cells treated with metformin.

KEY FINDINGS

We found that metformin significantly impaired hepatoma cell proliferation by inhibiting the glycolytic flux via PFK1 blockade. Interestingly, activation of PFK1 by F2,6BP reverses the inhibitory effect of metformin on hepatoma cell proliferation and glycolysis. Mechanistically, PFKFB3，a potent allosteric activator of PFK1, was markedly suppressed through inhibiting hypoxia-induced factor 1 (HIF-1α) accumulation mediated by metformin.

SIGNIFICANCE

Taken together these data indicate that HIF-1α/PFKFB3/PFK1 regulatory axis is a vital determinant of glucose metabolic reprogramming in hepatocellular carcinoma, which gives new insights into the action of metformin in combatting liver cancer.

SREBP-1 inhibitor Betulin enhances the antitumor effect of Sorafenib on hepatocellular carcinoma via restricting cellular glycolytic activity

Lipid metabolism that correlates tightly to the glucose metabolic regulation in malignant cells includes hepatocellular carcinoma (HCC) cells. The transcription factor Sterol Regulatory Element Binding Protein 1 (SREBP-1), a regulator of fatty acid synthesis, has been shown to pivotally regulate the proliferation and metastasis of HCC cells. However, the intrinsic mechanism by which SREBP-1 regulates the survival of HCC cells remains unclear. In this study, among HCC patients who had dismal responses to Sorafenib, a high SREBP-1 level was found in the tumors and correlated to poor survival. This observation suggested the negative role of SREBP-1 in clinical HCC prognosis. Our mechanistical studies reveal that the inhibition of SREBP-1 via its inhibitor Betulin suppresses cellular glucose metabolism. In addition to the reduced glycolytic activity, a thwarted metastatic potential was observed in HCC cells upon Betulin administration. Moreover, our data show that SREBP-1 inhibition facilitated the antitumor effects of Sorafenib on HCC cells and xenograft tumors.

Arsenic-induced metabolic shift triggered by the loss of miR-199a-5p through Sp1-dependent DNA methylation

Inorganic arsenic is an environmental carcinogen that poses a major global public health risk. A high percentage of drinking water from wells in the U.S. contains higher-than-normal levels of arsenic, suggesting an increased risk of arsenic-induced deleterious effects. In addition to primary preventive measures, therapeutic strategies need to effectively address and integrate multiple molecular mechanisms underlying arsenic-induced carcinogenesis. We previously showed that the loss of miR-199a-5p in arsenic-transformed cells is pivotal to promote arsenic-induced angiogenesis and tumor growth in lung epithelial cells. In this study, we further showed that subacute or chronic exposure to arsenic diminished miR-199a-5p levels largely due to DNA methylation, which was achieved by increased DNA methyltransferase-1 (DNMT1) activity, mediated by the formation of specific protein 1 (Sp1)/DNMT1 complex. In addition to the DNA hypermethylation, arsenic exposure also repressed miR-199a transcription through a transcriptional repressor Sp1. We further identified an association between miR-199a-5p repression and the arsenic-mediated energy metabolic shift, as reflected by mitochondria defects and a switch to glycolysis, in which a glycolytic enzyme pyruvate kinase 2 (PKM2) was a functional target of miR-199a-5p. Taken together, the repression of miR-199a-5p through both Sp1-dependent DNA methylation and Sp1 transcriptional repression promotes an arsenic-mediated metabolic shift from mitochondria respiration to aerobic glycolysis via PKM2.

Long non-coding RNA HOTTIP promotes hypoxia-induced glycolysis through targeting miR-615-3p/HMGB3 axis in non-small cell lung cancer cells

Increased glycolysis under hypoxic stress is a fundamentally important feature of non-small cell lung cancer (NSCLC) cells, but molecular mechanisms of hypoxia on glycolysis remain elusive. Herein, we aimed to explore whether lncRNAs and miRNAs are involved in the glycolytic reprogramming under hypoxic conditions. The levels of HOXA transcript at the distal tip (HOTTIP), miR-615-3p and high mobility group box 3 (HMGB3) mRNA were assessed by qRT-PCR. Western blot was performed to determine the protein expression of hexokinase 2 (HK-2) and HMGB3. Glucose consumption and lactate production were analyzed using a respective assay kit. The targeted correlation between miR-615-3p and HOTTIP or HMGB3 was verified using dual-luciferase reporter and RNA immunoprecipition assays. Our data revealed that HOTTIP was upregulated and miR-615-3p was downregulated in NSCLC tissues and cells. Hypoxia induced glycolysis, increased HOTTIP and HMGB3 mRNA levels and repressed miR-615-3p expression in NSCLC cells. HOTTIP deficiency or miR-615-3p expression restoration repressed hypoxia-induced glycolysis. Moreover, HOTTIP acted as a molecular sponge for miR-615-3p and HMGB3 was a direct target of miR-615-3p. The inhibitory effect of HOTTIP deficiency on glycolysis under hypoxic exposure was reversed by miR-615-3p restoration. Additionally, HOTTIP regulated HMGB3 expression by acting as a molecular sponge of miR-615-3p in NSCLC cells. In conclusion, our study suggested that HOTTIP might promote glycolysis under hypoxic conditions at least partly through regulating miR-615-3p/HMGB3 axis in NSCLC cells. Targeting HOTTIP might be a promising therapeutic strategy for NSCLC treatment.