miR-122 targets pyruvate kinase M2 and affects metabolism of hepatocellular carcinoma

Research progress on the role of adipocyte exosomes in cancer progression

Exosomes, minute vesicles ubiquitously released by diverse cell types, serve as critical mediators in intercellular communication. Their pathophysiological relevance, especially in malignancies, has garnered significant attention. A meticulous exploration of the exosomal impact on cancer development has unveiled avenues for innovative and clinically valuable techniques. The cargo conveyed by exosomes exerts transformative effects on both local and distant microenvironments, thereby influencing a broad spectrum of biological responses in recipient cells. These membrane-bound extracellular vesicles (EVs) play a pivotal role in delivering bioactive molecules among cells and organs. Cellular and biological processes in recipient cells, ranging from stromal cell reprogramming to immunological responses, extracellular matrix formation, and modulation of cancer cell activation, expansion, and metastasis, are subject to exosome-mediated cell-to-cell communication. Moreover, exosomes have been implicated in endowing cancer cells with resistance to treatment. Extensive research has explored the potential of exosomes as therapeutic targets and diagnostic indicators. This comprehensive review seeks to provide an in-depth understanding of the pivotal components and roles of exosomes in tumorigenesis, growth, progression, and therapeutic responses. The insights into the multifaceted involvement of exosomes in malignant cancers are essential for the scientific community, fostering the development of novel therapeutic and diagnostic strategies in the relentless pursuit of cancer.

New and Old Key Players in Liver Cancer

Liver cancer represents a major health problem worldwide with growing incidence and high mortality, hepatocellular carcinoma (HCC) being the most frequent. Hepatocytes are likely the cellular origin of most HCCs through the accumulation of genetic alterations, although hepatic progenitor cells (HPCs) might also be candidates in specific cases, as discussed here. HCC usually develops in a context of chronic inflammation, fibrosis, and cirrhosis, although the role of fibrosis is controversial. The interplay between hepatocytes, immune cells and hepatic stellate cells is a key issue. This review summarizes critical aspects of the liver tumor microenvironment paying special attention to platelets as new key players, which exert both pro- and anti-tumor effects, determined by specific contexts and a tight regulation of platelet signaling. Additionally, the relevance of specific signaling pathways, mainly HGF/MET, EGFR and TGF-β is discussed. HGF and TGF-β are produced by different liver cells and platelets and regulate not only tumor cell fate but also HPCs, inflammation and fibrosis, these being key players in these processes. The role of C3G/RAPGEF1, required for the proper function of HGF/MET signaling in HCC and HPCs, is highlighted, due to its ability to promote HCC growth and, regulate HPC fate and platelet-mediated actions on liver cancer.

The role and mechanism of action of microRNA-122 in cancer: Focusing on the liver

microRNA-122 (miR-122) is a highly conserved microRNA that is predominantly expressed in the liver and plays a critical role in the regulation of liver metabolism. Recent studies have shown that miR-122 is involved in the pathogenesis of various types of cancer, particularly liver cancer. In this sense, The current findings highlighted the potential role of miR-122 in regulating many vital processes in cancer pathophysiology, including apoptosis, signaling pathway, cell metabolism, immune system response, migration, and invasion. These results imply that miR-122, which has been extensively studied for its biological functions and potential therapeutic applications, acts as a tumor suppressor or oncogene in cancer development. We first provide an overview and summary of the physiological function and mode of action of miR-122 in liver cancer. We will examine the various signaling pathways and molecular mechanisms through which miR-122 exerts its effects on cancer cells, including the regulation of oncogenic and tumor suppressor genes, the modulation of cell proliferation and apoptosis, and the regulation of metastasis. Most importantly, we will also discuss the potential diagnostic and therapeutic applications of miR-122 in cancer, including the development of miRNA-based biomarkers for cancer diagnosis and prognosis, and the potential use of miR-122 as a therapeutic target for cancer treatment.

Uncovering Novel Roles of miR-122 in the Pathophysiology of the Liver: Potential Interaction with NRF1 and E2F4 Signaling

MicroRNA miR-122 plays a pivotal role in liver function. Despite numerous studies investigating this miRNA, the global network of genes regulated by miR-122 and its contribution to the underlying pathophysiological mechanisms remain largely unknown. To gain a deeper understanding of miR-122 activity, we employed two complementary approaches. Firstly, through transcriptome analysis of polyribosome-bound RNAs, we discovered that miR-122 exhibits potential antagonistic effects on specific transcription factors known to be dysregulated in liver disease, including nuclear respiratory factor-1 (NRF1) and the E2F transcription factor 4 (E2F4). Secondly, through proteome analysis of hepatoma cells transfected with either miR-122 mimic or antagomir, we discovered changes in several proteins associated with increased malignancy. Interestingly, many of these proteins were reported to be transcriptionally regulated by NRF1 and E2F4, six of which we validated as miR-122 targets. Among these, a negative correlation was observed between miR-122 and glucose-6-phosphate dehydrogenase levels in the livers of patients with hepatitis B virus-associated hepatocellular carcinoma. This study provides novel insights into potential alterations of molecular pathway occurring at the early stages of liver disease, driven by the dysregulation of miR-122 and its associated genes.

Small extracellular vesicle-mediated metabolic reprogramming: from tumors to pre-metastatic niche formation

Metastasis, the spread of a tumor or cancer from the primary site of the body to a secondary site, is a multi-step process in cancer progression, accounting for various obstacles in cancer treatment and most cancer-related deaths. Metabolic reprogramming refers to adaptive metabolic changes that occur in cancer cells in the tumor microenvironment (TME) to enhance their survival ability and metastatic potential. Stromal cell metabolism also changes to stimulate tumor proliferation and metastasis. Metabolic adaptations of tumor and non-tumor cells exist not only in the TME but also in the pre-metastatic niche (PMN), a remote TME conducive for tumor metastasis. As a novel mediator in cell-to-cell communication, small extracellular vesicles (sEVs), which have a diameter of 30-150 nm, reprogram metabolism in stromal and cancer cells within the TME by transferring bioactive substances including proteins, mRNAs and miRNAs (microRNAs). sEVs can be delivered from the primary TME to PMN, affecting PMN formation in stroma rewriting, angiogenesis, immunological suppression and matrix cell metabolism by mediating metabolic reprogramming. Herein, we review the functions of sEVs in cancer cells and the TME, how sEVs facilitate PMN establishment to trigger metastasis via metabolic reprogramming, and the prospective applications of sEVs in tumor diagnosis and treatment. Video Abstract.

Functional importance of glucose transporters and chromatin epigenetic factors in Glioblastoma Multiforme (GBM): possible therapeutics

Glioblastoma Multiforme (GBM) is an aggressive brain cancer affecting glial cells and is chemo- and radio-resistant. Glucose is considered the most vital energy source for cancer cell proliferation. During metabolism, hexose molecules will be transported into the cells via transmembrane proteins known as glucose transporter (GLUT). Among them, GLUT-1 and GLUT-3 play pivotal roles in glucose transport in GBM. Knockdown studies have established the role of GLUT-1, and GLUT-3 mediated glucose transport in GBM cells, providing insight into GLUT-mediated cancer signaling and cancer aggressiveness. This review focussed on the vital role of GLUT-1 and GLUT-3 proteins, which regulate glucose transport. Recent studies have identified the role of GLUT inhibitors in effective cancer prevention. Several of them are in clinical trials. Understanding and functional approaches towards glucose-mediated cell metabolism and chromatin epigenetics will provide valuable insights into the mechanism of cancer aggressiveness, cancer stemness, and chemo-resistance in Glioblastoma Multiforme (GBM). This review summarizes the role of GLUT inhibitors, micro-RNAs, and long non-coding RNAs that aid in inhibiting glucose uptake by the GBM cells and other cancer cells leading to the identification of potential therapeutic, prognostic as well as diagnostic markers. Furthermore, the involvement of epigenetic factors, such as microRNAs, in regulating glycolytic genes was demonstrated.

RNA-Interference-Mediated miR-122-Based Gene Regulation in Colon Cancer, a Structural In Silico Analysis

The role of microRNA 122 (miR-122) in colorectal cancer (CRC) has not been widely investigated. In the current study, we aimed to identify the prominent gene and protein interactors of miR122 in CRC. Based on their binding affinity, these targets were chosen as candidate genes for the creation of miR122-mRNA duplexes. Following this, we examined the miRNA-mediated silencing mechanism using the gene-silencing complex protein Argonaute (AGO). Public databases, STRING, and GeneMANIA were utilized to identify major proteins and genes interacting with miR-122. DAVID, PANTHER, UniProt, FunRich, miRwalk, and KEGG were used for functional annotation, pathway enrichment, binding affinity analysis, and expression of genes in different stages of cancer. Three-dimensional duplexes of hub genes and miR-122 were created using the RNA composer, followed by molecular interaction analysis using molecular docking with the AGO protein. We analyzed, classified, and scrutinized 93 miR-122 interactors using various bioinformatic approaches. A total of 14 hub genes were categorized as major interactors of miR-122. The study confirmed the role of various experimentally documented miR-122 interactors such as MTDH (Q86UE4), AKT1 (P31749), PTPN1 (P18031), MYC (P01106), GSK3B (P49841), RHOA (P61586), and PIK3CG (P48736) and put forth several novel interactors, with AKT3 (Q9Y243), NCOR2 (Q9Y618), PIK3R2 (O00459), SMAD4 (P61586), and TGFBR1 (P36897). Double-stranded RNA duplexes of the strongest interactors were found to exhibit higher binding affinity with AGO. In conclusions, the study has explored the role of miR-122 in CRC and has identified a closely related group of genes influencing the prognosis of CRC in multiple ways. Further, these genes prove to be targets of gene silencing through RNA interference and might serve as effective therapeutic targets in understanding and treating CRC.

Expressional and functional characteristics of checkpoint kinase 1 as a prognostic biomarker in hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is the most common pathological subtype of liver cancer and is the third leading cause of cancer death worldwide. Checkpoint kinase 1 (CHEK1), an essential serine/threonine kinase that regulates the cell cycle, is reported to be associated with carcinogenesis. However, the biological role and clinical significance of CHEK1 in HCC are still incompletely known.

Methods

In this research, CHEK1 messenger RNA (mRNA) levels in various liver hepatocellular carcinoma (LIHC) cohorts from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases were evaluated. The Kaplan-Meier database was applied to identify the correlation between survival time and CHEK1 expression in patients with HCC. Gene set enrichment analysis (GSEA) was performed to explore the potential mechanism of CHEK1 in HCC, and NetworkAnalyst v. 3.0 (https://www.networkanalyst.ca/) was used to construct the regulatory networks of CHEK1 in HCC. Discriminant Regulon Expression Analysis (DoRothEA) was used to detect the activity of transcriptional factors (TFs) in gene-enriched cells (EC) with CHEK1 coexpression. In vitro experiments were conducted to investigate the effects of CHEK1 on the biological function of HCC cells.

Results

The CHEK1 mRNA level was overexpressed in HCC, and increased CHEK1 expression correlated with poor survival outcomes. The homo sapiens-microRNA-195 (hsa-miR-195) may have contributed to the upregulation of CHEK1 in HCC. GSEA and NetworkAnalyst v. 3.0 showed that CHEK1 played a crucial part in tumor proliferation of HCC and may be regulated by TF E2F1. DoRothEA showed increased transcriptional activity of E2F1 in gene-EC with CHEK1 coexpression. Moreover, experiments of cell function showed that the knockdown of CHEK1 weakened the aggressive behavior and proliferation of HCC cells. Overexpression of E2F1 increased the proliferation and invasion of HCC cells in vitro, while the silencing of CHEK1 dampened cell invasion induced by E2F1 overexpression.

Conclusions

These results identified the prognostic significance and expression characteristics of CHEK1 in HCC through bioinformatics analysis and experimental verification. This lays the foundation for further research on the diagnosis and treatment of HCC.

Non-Coding RNAs in Hepatocellular Carcinoma

Liver cancer ranks as the fourth leading cause of cancer-related deaths. Despite extensive research efforts aiming to evaluate the biological mechanisms underlying hepatocellular carcinoma (HCC) development, little has been translated towards new diagnostic and treatment options for HCC patients. Historically, the focus has been centered on coding RNAs and their respective proteins. However, significant advances in sequencing and RNA detection technologies have shifted the research focus towards non-coding RNAs (ncRNA), as well as their impact on HCC development and progression. A number of studies reported complex post-transcriptional interactions between various ncRNA and coding RNA molecules. These interactions offer insights into the role of ncRNAs in both the known pathways leading to oncogenesis, such as dysregulation of p53, and lesser-known mechanisms, such as small nucleolar RNA methylation. Studies investigating these mechanisms have identified prevalent ncRNA changes in microRNAs, snoRNAs, and long non-coding RNAs that can both pre- and post-translationally regulate key factors in HCC progression. In this review, we present relevant publications describing ncRNAs to summarize the impact of different ncRNA species on liver cancer development and progression and to evaluate recent attempts at clinical translation.

MicroRNAs as Regulators of Cancer Cell Energy Metabolism

To adapt to the tumor environment or to escape chemotherapy, cancer cells rapidly reprogram their metabolism. The hallmark biochemical phenotype of cancer cells is the shift in metabolic reprogramming towards aerobic glycolysis. It was thought that this metabolic shift to glycolysis alone was sufficient for cancer cells to meet their heightened energy and metabolic demands for proliferation and survival. Recent studies, however, show that cancer cells rely on glutamine, lipid, and mitochondrial metabolism for energy. Oncogenes and scavenging pathways control many of these metabolic changes, and several metabolic and tumorigenic pathways are post-transcriptionally regulated by microRNA (miRNAs). Genes that are directly or indirectly responsible for energy production in cells are either negatively or positively regulated by miRNAs. Therefore, some miRNAs play an oncogenic role by regulating the metabolic shift that occurs in cancer cells. Additionally, miRNAs can regulate mitochondrial calcium stores and energy metabolism, thus promoting cancer cell survival, cell growth, and metastasis. In the electron transport chain (ETC), miRNAs enhance the activity of apoptosis-inducing factor (AIF) and cytochrome c, and these apoptosome proteins are directed towards the ETC rather than to the apoptotic pathway. This review will highlight how miRNAs regulate the enzymes, signaling pathways, and transcription factors of cancer cell metabolism and mitochondrial calcium import/export pathways. The review will also focus on the metabolic reprogramming of cancer cells to promote survival, proliferation, growth, and metastasis with an emphasis on the therapeutic potential of miRNAs for cancer treatment.

Molecular Targets and Signaling Pathways of microRNA-122 in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the leading global causes of cancer mortality. MicroRNAs (miRNAs) are small interfering RNAs that alleviate the levels of protein expression by suppressing translation, inducing mRNA cleavage, and promoting mRNA degradation. miR-122 is the most abundant miRNA in the liver and is responsible for several liver-specific functions, including metabolism, cellular growth and differentiation, and hepatitis virus replication. Recent studies have shown that aberrant regulation of miR-122 is a key factor contributing to the development of HCC. In this review, the signaling pathways and the molecular targets of miR-122 involved in the progression of HCC have been summarized, and the importance of miR-122 in therapy has been discussed.

Downregulation of miR-122-5p Activates Glycolysis via PKM2 in Kupffer Cells of Rat and Mouse Models of Non-Alcoholic Steatohepatitis

Non-alcoholic steatohepatitis (NASH) has pathological characteristics similar to those of alcoholic hepatitis, despite the absence of a drinking history. The greatest threat associated with NASH is its progression to cirrhosis and hepatocellular carcinoma. The pathophysiology of NASH is not fully understood to date. In this study, we investigated the pathophysiology of NASH from the perspective of glycolysis and the Warburg effect, with a particular focus on microRNA regulation in liver-specific macrophages, also known as Kupffer cells. We established NASH rat and mouse models and evaluated various parameters including the liver-to-body weight ratio, blood indexes, and histopathology. A quantitative phosphoproteomic analysis of the NASH rat model livers revealed the activation of glycolysis. Western blotting and immunohistochemistry results indicated that the expression of pyruvate kinase muscle 2 (PKM2), a rate-limiting enzyme of glycolysis, was upregulated in the liver tissues of both NASH models. Moreover, increases in PKM2 and p-PKM2 were observed in the early phase of NASH. These observations were partially induced by the downregulation of microRNA122-5p (miR-122-5p) and occurred particularly in the Kupffer cells. Our results suggest that the activation of glycolysis in Kupffer cells during NASH was partially induced by the upregulation of PKM2 via miR-122-5p suppression.

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.

Therapeutic Metabolic Reprograming Using microRNAs: From Cancer to HIV Infection

MicroRNAs (miRNAs) are crucial regulators of cellular processes, including metabolism. Attempts to use miRNAs as therapeutic agents are being explored in several areas, including the control of cancer progression. Recent evidence suggests fine tuning miRNA activity to reprogram tumor cell metabolism has enormous potential as an alternative treatment option. Indeed, cancer growth is known to be linked to profound metabolic changes. Likewise, the emerging field of immunometabolism is leading to a refined understanding of how immune cell proliferation and function is governed by glucose homeostasis. Different immune cell types are now known to have unique metabolic signatures that switch in response to a changing environment. T-cell subsets exhibit distinct metabolic profiles which underlie their alternative differentiation and phenotypic functions. Recent evidence shows that the susceptibility of CD4+ T-cells to HIV infection is intimately linked to their metabolic activity, with many of the metabolic features of HIV-1-infected cells resembling those found in tumor cells. In this review, we discuss the use of miRNA modulation to achieve metabolic reprogramming for cancer therapy and explore the idea that the same approach may serve as an effective mechanism to restrict HIV replication and eliminate infected cells.

A Perspective on Medicinal Chemistry Approaches for Targeting Pyruvate Kinase M2

The allosteric regulation of pyruvate kinase M2 (PKM2) affects the switching of the PKM2 protein between the high-activity and low-activity states that allow ATP and lactate production, respectively. PKM2, in its low catalytic state (dimeric form), is chiefly active in metabolically energetic cells, including cancer cells. More recently, PKM2 has emerged as an attractive target due to its role in metabolic dysfunction and other interrelated conditions. PKM2 (dimer) activity can be inhibited by modulating PKM2 dimer-tetramer dynamics using either PKM2 inhibitors that bind at the ATP binding active site of PKM2 (dimer) or PKM2 activators that bind at the allosteric site of PKM2, thus activating PKM2 from the dimer formation to the tetrameric formation. The present perspective focuses on medicinal chemistry approaches to design and discover PKM2 inhibitors and activators and further provides a scope for the future design of compounds targeting PKM2 with better efficacy and selectivity.

Lactate: The Mediator of Metabolism and Immunosuppression

The Warburg effect, one of the hallmarks of tumors, produces large amounts of lactate and generates an acidic tumor microenvironment via using glucose for glycolysis. As a metabolite, lactate not only serves as a substrate to provide energy for supporting cell growth and development but also acts as an important signal molecule to affect the biochemical functions of intracellular proteins and regulate the biological functions of different kinds of cells. Notably, histone lysine lactylation (Kla) is identified as a novel post-modification and carcinogenic signal, which provides the promising and potential therapeutic targets for tumors. Therefore, the metabolism and functional mechanism of lactate are becoming one of the hot fields in tumor research. Here, we review the production of lactate and its regulation on immunosuppressive cells, as well as the important role of Kla in hepatocellular carcinoma. Lactate and Kla supplement the knowledge gap in oncology and pave the way for exploring the mechanism of oncogenesis and therapeutic targets. Research is still needed in this field.

Oxygen sensing, mitochondrial biology and experimental therapeutics for pulmonary hypertension and cancer

The homeostatic oxygen sensing system (HOSS) optimizes systemic oxygen delivery. Specialized tissues utilize a conserved mitochondrial sensor, often involving NDUFS2 in complex I of the mitochondrial electron transport chain, as a site of pO₂-responsive production of reactive oxygen species (ROS). These ROS are converted to a diffusible signaling molecule, hydrogen peroxide (H₂O₂), by superoxide dismutase (SOD2). H₂O₂ exits the mitochondria and regulates ion channels and enzymes, altering plasma membrane potential, intracellular Ca²⁺ and Ca²⁺-sensitization and controlling acute, adaptive, responses to hypoxia that involve changes in ventilation, vascular tone and neurotransmitter release. Subversion of this O₂-sensing pathway creates a pseudohypoxic state that promotes disease progression in pulmonary arterial hypertension (PAH) and cancer. Pseudohypoxia is a state in which biochemical changes, normally associated with hypoxia, occur despite normal pO₂. Epigenetic silencing of SOD2 by DNA methylation alters H₂O₂ production, activating hypoxia-inducible factor 1α, thereby disrupting mitochondrial metabolism and dynamics, accelerating cell proliferation and inhibiting apoptosis. Other epigenetic mechanisms, including dysregulation of microRNAs (miR), increase pyruvate dehydrogenase kinase and pyruvate kinase muscle isoform 2 expression in both diseases, favoring uncoupled aerobic glycolysis. This Warburg metabolic shift also accelerates cell proliferation and impairs apoptosis. Disordered mitochondrial dynamics, usually increased mitotic fission and impaired fusion, promotes disease progression in PAH and cancer. Epigenetic upregulation of dynamin-related protein 1 (Drp1) and its binding partners, MiD49 and MiD51, contributes to the pathogenesis of PAH and cancer. Finally, dysregulation of intramitochondrial Ca²⁺, resulting from impaired mitochondrial calcium uniporter complex (MCUC) function, links abnormal mitochondrial metabolism and dynamics. MiR-mediated decreases in MCUC function reduce intramitochondrial Ca²⁺, promoting Warburg metabolism, whilst increasing cytosolic Ca²⁺, promoting fission. Epigenetically disordered mitochondrial O₂-sensing, metabolism, dynamics, and Ca²⁺ homeostasis offer new therapeutic targets for PAH and cancer. Promoting glucose oxidation, restoring the fission/fusion balance, and restoring mitochondrial calcium regulation are promising experimental therapeutic strategies.

miR-183-5p Promotes HCC Migration/Invasion via Increasing Aerobic Glycolysis

Background

The mortality and morbidity of hepatocellular carcinoma (HCC) are still unacceptably high, despite decades of extensive studies. Aerobic glycolysis is a hallmark of cancer metabolism, closely relating to invasion and metastasis of HCC. MicroRNAs (miRNAs) are involved in the regulation of aerobic glycolysis. miR-183-5p, an oncogenic miRNA, is highly expressed in HCC, but the regulatory mechanism of miR-183-5p in migration, invasion and aerobic glycolysis in HCC remains unclear.

Purpose

To elucidate whether miR-183-5p affects aerobic glycolysis to regulate the migration and invasion of HCC, and to explore its regulatory mechanism.

Methods

We attempted to observe the effects of miR-183-5p on the migration and invasion of HepG2 cells by a wound-healing assay and Transwell assays. The effect of miR-183-5p on glycolysis was determined by glucose uptake and lactate generation. Western blot and qPCR were used to detect the relevant proteins and miRNA expression.

Results

Our results show that miR-183-5p promoted migration and invasion, enhanced glycolysis via increasing glucose uptake and lactate generation, and up-regulated glycolysis-related gene (PKM2, HK2, LDHA, GLUT1) expression in HepG2 cells. Further experiments indicated that miR-183-5p could decrease PTEN expression, but increased Akt, p-Akt and mTOR expression in HepG2 cells.

Conclusion

These findings suggest that miR-183-5p may promote HCC migration and invasion via increasing aerobic glycolysis through targeting PTEN and then activating Akt/mTOR signaling.

Histone Methyltransferase G9a-Promoted Progression of Hepatocellular Carcinoma Is Targeted by Liver-Specific Hsa-miR-122

Simple Summary

Targeting epigenetic alterations in hepatocellular carcinoma (HCC) provides therapeutic options in addition to traditional treatments. The aim of our study was to evaluate the potential of targeting histone methyltransferase G9a in the development of a therapeutic target. We confirmed the prognostic values of mRNA and protein levels of G9a expression in HCC respectively from public database and tissue microarray. We also confirmed the aggressive phenotypes supported by G9a in both HBV+ and HBV− HCC cells. The identification of a regulation axis between liver-specific tumor suppressor miR-122 and G9a further supported the important roles of G9a during the tumorigenesis and progression of HCC. Combination of lower miR-122 and higher G9a levels may provide prognostic potential for poor clinical outcomes and therapeutic potential for epigenetic targeting therapies.

Abstract

Hepatocellular carcinoma (HCC) accounts for the majority of primary liver cancers, which is the second most lethal tumor worldwide. Epigenetic deregulation is a common trait observed in HCC. Recently, increasing evidence suggested that the G9a histone methyltransferase might be a novel regulator of HCC development. However, several HCC cell lines were recently noted to have HeLa cell contamination or to have been derived from non-hepatocellular origin, suggesting that functional validation of G9a in proper HCC models is still required. Herein, we first confirmed that higher G9a messenger RNA and protein expression levels were correlated with poor overall survival (OS) and disease-free survival (DFS) rates of HCC patients from The Cancer Genome Atlas (TCGA) dataset and our recruited HCC cohort. In an in vitro functional evaluation of HCC cells, HCC36 (hepatitis B virus-positive (HBV+) and Mahlavu (HBV−)) cells showed that G9a participated in promoting cell proliferation, colony formation, and migration/invasion abilities. Moreover, orthotopic inoculation of G9a-depleted Mahlavu cells in NOD-SCID mice also resulted in a significantly decreased tumor burden compared to the control group. Furthermore, after surveying microRNA (miRNA; miR) prediction databases, we identified the liver-specific miR-122 as a G9a-targeting miRNA. In various HCC cell lines, we observed that miR-122 expression levels tended to be inversely correlated to G9a expression levels. In clinical HCC specimens, a significant inverse correlation of miR-122 and G9a mRNA expression levels was also observed. Functionally, the colony formation and invasive ability were attenuated in miR-122-overexpressing HCC cells. HCC patients with low miR-122 and high G9a expression levels had the worst OS and DFS rates compared to others. Together, our results confirmed the importance of altered G9a expression during HCC progression and discovered that a novel liver-specific miR-122-G9a regulatory axis exists.

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.

From Liver Cirrhosis to Cancer: The Role of Micro-RNAs in Hepatocarcinogenesis

In almost all cases, hepatocellular carcinoma (HCC) develops as the endpoint of a sequence that starts with chronic liver injury, progresses to liver cirrhosis, and finally, over years and decades, results in liver cancer. Recently, the role of non-coding RNA such as microRNA (miRNA) has been demonstrated in the context of chronic liver diseases and HCC. Moreover, data from a phase II trial suggested a potential role of microRNAs as therapeutics in hepatitis-C-virus infection, representing a significant risk factor for development of liver cirrhosis and HCC. Despite progress in the clinical management of chronic liver diseases, pharmacological treatment options for patients with liver cirrhosis and/or advanced HCC are still limited. With their potential to regulate whole networks of genes, miRNA might be used as novel therapeutics in these patients but could also serve as biomarkers for improved patient stratification. In this review, we discuss available data on the role of miRNA in the transition from liver cirrhosis to HCC. We highlight opportunities for clinical translation and discuss open issues applicable to future developments.

The Role of PKM2 in Metabolic Reprogramming: Insights into the Regulatory Roles of Non-Coding RNAs

Pyruvate kinase is a key regulator in glycolysis through the conversion of phosphoenolpyruvate (PEP) into pyruvate. Pyruvate kinase exists in various isoforms that can exhibit diverse biological functions and outcomes. The pyruvate kinase isoenzyme type M2 (PKM2) controls cell progression and survival through the regulation of key signaling pathways. In cancer cells, the dimer form of PKM2 predominates and plays an integral role in cancer metabolism. This predominance of the inactive dimeric form promotes the accumulation of phosphometabolites, allowing cancer cells to engage in high levels of synthetic processing to enhance their proliferative capacity. PKM2 has been recognized for its role in regulating gene expression and transcription factors critical for health and disease. This role enables PKM2 to exert profound regulatory effects that promote cancer cell metabolism, proliferation, and migration. In addition to its role in cancer, PKM2 regulates aspects essential to cellular homeostasis in non-cancer tissues and, in some cases, promotes tissue-specific pathways in health and diseases. In pursuit of understanding the diverse tissue-specific roles of PKM2, investigations targeting tissues such as the kidney, liver, adipose, and pancreas have been conducted. Findings from these studies enhance our understanding of PKM2 functions in various diseases beyond cancer. Therefore, there is substantial interest in PKM2 modulation as a potential therapeutic target for the treatment of multiple conditions. Indeed, a vast plethora of research has focused on identifying therapeutic strategies for targeting PKM2. Recently, targeting PKM2 through its regulatory microRNAs, long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs) has gathered increasing interest. Thus, the goal of this review is to highlight recent advancements in PKM2 research, with a focus on PKM2 regulatory microRNAs and lncRNAs and their subsequent physiological significance.

Differential miRNA Expression in Human Macrophage-Like Cells Infected with Histoplasma capsulatum Yeasts Cultured in Planktonic and Biofilm Forms

Histoplasma capsulatum affects healthy and immunocompromised individuals, sometimes causing a severe disease. This fungus has two morphotypes, the mycelial (infective) and the yeast (parasitic) phases. MicroRNAs (miRNAs) are small RNAs involved in the regulation of several cellular processes, and their differential expression has been associated with many disease states. To investigate miRNA expression in host cells during H. capsulatum infection, we studied the changes in the miRNA profiles of differentiated human macrophages infected with yeasts from two fungal strains with different virulence, EH-315 (high virulence) and 60I (low virulence) grown in planktonic cultures, and EH-315 grown in biofilm form. MiRNA profiles were evaluated by means of reverse transcription-quantitative polymerase chain reaction using a commercial human miRNome panel. The target genes of the differentially expressed miRNAs and their corresponding signaling pathways were predicted using bioinformatics analyses. Here, we confirmed biofilm structures were present in the EH-315 culture whose conditions facilitated producing insoluble exopolysaccharide and intracellular polysaccharides. In infected macrophages, bioinformatics analyses revealed especially increased (hsa-miR-99b-3p) or decreased (hsa-miR-342-3p) miRNAs expression levels in response to infection with biofilms or both growth forms of H. capsulatum yeasts, respectively. The results of miRNAs suggested that infection by H. capsulatum can affect important biological pathways of the host cell, targeting two genes: one encoding a protein that is important in the cortical cytoskeleton; the other, a protein involved in the formation of stress granules. Expressed miRNAs in the host’s response could be proposed as new therapeutic and/or diagnostic tools for histoplasmosis.

PTBP1-targeting microRNAs regulate cancer-specific energy metabolism through the modulation of PKM1/M2 splicing

Understanding of the microRNAs (miRNAs) regulatory system has become indispensable for physiological/oncological research. Tissue and organ specificities are key features of miRNAs that should be accounted for in cancer research. Further, cancer-specific energy metabolism, referred to as the Warburg effect, has been positioned as a key cancer feature. Enhancement of the glycolysis pathway in cancer cells is what primarily characterizes the Warburg effect. Pyruvate kinase M1/2 (PKM1/2) are key molecules of the complex glycolytic system; their distribution is organ-specific. In fact, PKM2 overexpression has been detected in various cancer cells. PKM isoforms are generated by alternative splicing by heterogeneous nuclear ribonucleoproteins. In addition, polypyrimidine tract-binding protein 1 (PTBP1) is essential for the production of PKM2 in cancer cells. Recently, several studies focusing on non-coding RNA elucidated PTBP1 or PKM2 regulatory mechanisms, including control by miRNAs, and their association with cancer. In this review, we discuss the strong relationship between the organ-specific distribution of miRNAs and the expression of PKM in the context of PTBP1 gene regulation. Moreover, we focus on the impact of PTBP1-targeting miRNA dysregulation on the Warburg effect.

Animal Models: A Useful Tool to Unveil Metabolic Changes in Hepatocellular Carcinoma

Simple Summary

Hepatocellular carcinoma (HCC) represents an important health problem. At the moment, systemic therapies offered only modest clinical benefits. Thus, HCC represents a cancer extremely difficult to treat, and therapeutic breakthroughs are urgently needed. Metabolic reprogramming of neoplastic cells has been recognized as one of the core hallmarks of cancer. Experimental animal models represent an important tool that allows to investigate metabolic changes underlying HCC development and progression. In the present review, we characterize available rodent models of hepatocarcinogenesis. Moreover, we discuss the possibility that pharmacological targeting of Warburg metabolism may represent an additional tool to improve already available therapeutic approaches for HCC.

Abstract

Hepatocellular carcinoma (HCC) is one the most frequent and lethal human cancers. At present, no effective treatment for advanced HCC exist; therefore, the overall prognosis for HCC patients remains dismal. In recent years, a better knowledge of the signaling pathways involved in the regulation of HCC development and progression, has led to the identification of novel potential targets for therapeutic strategies. However, the obtained benefits from current therapeutic options are disappointing. Altered cancer metabolism has become a topic of renewed interest in the last decades, and it has been included among the core hallmarks of cancer. In the light of growing evidence for metabolic reprogramming in cancer, a wide number of experimental animal models have been exploited to study metabolic changes characterizing HCC development and progression and to further expand our knowledge of this tumor. In the present review, we discuss several rodent models of hepatocarcinogenesis, that contributed to elucidate the metabolic profile of HCC and the implications of these changes in modulating the aggressiveness of neoplastic cells. We also highlight the apparently contrasting results stemming from different animal models. Finally, we analyze whether these observations could be exploited to improve current therapeutic strategies for HCC.

Significant association of PKM2 and NQO1 proteins with poor prognosis in breast cancer

Pyruvate kinase M2 (PKM2) and NAD(P)H:quinone oxidoreductase-1 (NQO1) have been known to play significant functions in tumorigenesis and development. The association between PKM2 and NQO1 in breast cancer continues, however, to be unclear. In the present study, according to UALCAN and GEPIA database, the mRNA levels of PKM2 and NQO1 in breast primary tumor were significantly higher compared to normal breast tissue. Consonant with these findings, increased expression of both PKM2 and NQO1 were detected in clinical samples and BC cell lines. More importantly, consolidated high expression of NQO1 and PKM2 were obtained to be related with worse clinical stage, relapse, shorter relapse free survival (RFS), and poorer overall survival (OS) in human breast cancer. We subsequently found that knockdown of NQO1 reduced the protein level of PKM2 significantly. Moreover, deletion of PKM2 significantly reduced colony formation, migration and invasion of BC cells. A positive correlation between PKM2 and NQO1 expression was identified by immunohistochemical analyses of 108 specimens of breast cancer patients (rs = 0.60, P = 0.00). Finally, endogenous Co-IP demonstrated that PKM2 and NQO1 interact in breast cancer cells. The results of this study suggest that the correlation between NQO1 and PKM2 might play a critical role during breast tumourigenesis and serve as novel diagnostic biomarkers for breast cancer.

MicroRNA signature in hepatocellular carcinoma patients: identification of potential markers

MicroRNAs (miRNAs) play important roles in liver pathologies and they are potential biomarkers for diagnosis of liver diseases progression. Changes in miRNA sera expression can be used as non-invasive biomarkers for hepatocellular carcinoma (HCC). The aim of the study was to identify the miRNome profiling of HCC and its diagnostic value in distinguishing HCC from healthy individuals. Expression profiles of miRNAs in serum samples of 20 HCC patients and 10 healthy controls were detected. Whole miRNome profiling was done using next generation sequencing. Receiver operating characteristic (ROC) analysis was performed to assess the diagnostic performance of the deregulated miRNAs for discriminating HCC cases from healthy controls. MiRNA 142 was highly expressed in HCC (P value = 0.023) while miRNAs 191, 22, and 126 were higher in the controls (P value = 0.005, 0.034, 0.010 respectively). We have identified 5 novel miRNAs and they were highly expressed in HCC than controls. Analysis of ROC curve demonstrated that these deregulated miRNAs can be used as a reliable biomarker for detection of HCC with high diagnostic accuracy (AUC = 0.93). We have detected a panel of serum miRNAs that can be used as a reliable noninvasive screening biomarker of HCC. The study recommends further research to shed light on a possible role of the newly discovered novel miRNAs in HCC pathogenesis.

Glucose Metabolism and Oxidative Stress in Hepatocellular Carcinoma: Role and Possible Implications in Novel Therapeutic Strategies

Hepatocellular carcinoma (HCC) metabolism is redirected to glycolysis to enhance the production of metabolic compounds employed by cancer cells to produce proteins, lipids, and nucleotides in order to maintain a high proliferative rate. This mechanism drives towards uncontrolled growth and causes a further increase in reactive oxygen species (ROS), which could lead to cell death. HCC overcomes the problem generated by ROS increase by increasing the antioxidant machinery, in which key mechanisms involve glutathione, nuclear factor erythroid 2-related factor 2 (Nrf2), and hypoxia-inducible transcription factor (HIF-1α). These mechanisms could represent optimal targets for innovative therapies. The tumor microenvironment (TME) exerts a key role in HCC pathogenesis and progression. Various metabolic machineries modulate the activity of immune cells in the TME. The deregulated metabolic activity of tumor cells could impair antitumor response. Lactic acid-lactate, derived from the anaerobic glycolytic rate of tumor cells, as well as adenosine, derived from the catabolism of ATP, have an immunosuppressive activity. Metabolic reprogramming of the TME via targeted therapies could enhance the treatment efficacy of anti-cancer immunotherapy. This review describes the metabolic pathways mainly involved in the HCC pathogenesis and progression. The potential targets for HCC treatment involved in these pathways are also discussed.

MicroRNAs in Tumor Cell Metabolism: Roles and Therapeutic Opportunities

Dysregulated metabolism is a common feature of cancer cells and is considered a hallmark of cancer. Altered tumor-metabolism confers an adaptive advantage to cancer cells to fulfill the high energetic requirements for the maintenance of high proliferation rates, similarly, reprogramming metabolism confers the ability to grow at low oxygen concentrations and to use alternative carbon sources. These phenomena result from the dysregulated expression of diverse genes, including those encoding microRNAs (miRNAs) which are involved in several metabolic and tumorigenic pathways through its post-transcriptional-regulatory activity. Further, the identification of key actionable altered miRNA has allowed to propose novel targeted therapies to modulated tumor-metabolism. In this review, we discussed the different roles of miRNAs in cancer cell metabolism and novel miRNA-based strategies designed to target the metabolic machinery in human cancer.

Hepatitis C Virus Downregulates Core Subunits of Oxidative Phosphorylation, Reminiscent of the Warburg Effect in Cancer Cells

Hepatitis C Virus (HCV) mainly infects liver hepatocytes and replicates its single-stranded plus strand RNA genome exclusively in the cytoplasm. Viral proteins and RNA interfere with the host cell immune response, allowing the virus to continue replication. Therefore, in about 70% of cases, the viral infection cannot be cleared by the immune system, but a chronic infection is established, often resulting in liver fibrosis, cirrhosis and hepatocellular carcinoma (HCC). Induction of cancer in the host cells can be regarded to provide further advantages for ongoing virus replication. One adaptation in cancer cells is the enhancement of cellular carbohydrate flux in glycolysis with a reduction of the activity of the citric acid cycle and aerobic oxidative phosphorylation. To this end, HCV downregulates the expression of mitochondrial oxidative phosphorylation complex core subunits quite early after infection. This so-called aerobic glycolysis is known as the “Warburg Effect” and serves to provide more anabolic metabolites upstream of the citric acid cycle, such as amino acids, pentoses and NADPH for cancer cell growth. In addition, HCV deregulates signaling pathways like those of TNF-β and MAPK by direct and indirect mechanisms, which can lead to fibrosis and HCC.

Potential regulation by miRNAs on glucose metabolism in liver of common carp (Cyprinus carpio) at different temperatures

Water temperature can affect the metabolism of fish. Common carp (Cyprinus carpio) is a representative eurythermic fish that can survive at a wide range of ambient temperatures, allowing it to live in an extensive geographical range. The goal of this work was to study the glucose metabolism of common carp at different temperatures and determine the miRNAs involved in the regulation of glucose metabolism. We determined the indicators related to glucose metabolism after long-term temperature stress and constructed nine small RNA libraries of livers under different temperature stress (5 °C, 17 °C, and 30 °C, with three biological replicates for each temperature), and subjected these samples to high-throughput sequencing. A positive relationship was observed between weight gain rate (WGR) and temperature increase after 18 days of temperature stress. However, the glucose level in the plasma maintained a gentle decrease. Unexpectedly, liver lactic acid levels were elevated in HTG (high temperature group) and LTG (low temperature group). Six down-regulated miRNAs (miR-122, miR-30b, miR-15b-5p, miR-20a-5p, miR-1, and miR-7b) were identified as involved in the regulation of glycolysis. Twelve genes were predicted as targets of these miRNAs, and these genes are in pathways related to pyruvate metabolism, glycolysis/gluconeogenesis, and the citrate cycle (TCA cycle). The results allowed prediction of a potential regulatory network of miRNAs involved in the regulation of glycolysis. The target genes of six down-regulated miRNAs were up-regulated under temperature stress, including Aldolase C, fructose-bisphosphate, b (ALDOCB), multiple inositol-polyphosphate phosphatase 1 (MINPP1), phosphoenolpyruvate carboxykinase 1 (PCK1), pyruvate dehydrogenase E1 alpha 1 (PDHA1), aldehyde dehydrogenase 9 family member A1a (ALDH9A1A), Acetyl-coenzyme A synthetase (ACSS), lactate dehydrogenase b (LDH-b), and glyoxylate reductase/hydroxypyruvate reductase (GRHPR). Other key genes of glycolysis, glucose transporter 1 (GLUT-1), pyruvate kinase PKM (PKM), and mitochondrial pyruvate carrier (MPC) were significantly up-regulated in LTG and HTG. Overall, the results suggest that miRNAs maintain their energy requirements by regulating glycolysis and play an important role in the molecular response to cold and heat stress of common carp. These data provide the foundation for further studies of the role of miRNAs in environmental adaptation in fish.

Liver-Specific microRNA Identification in Farmed Carp, Labeo bata (Hamilton, 1822), Fed with Starch Diet Using High-Throughput Sequencing

The liver is an important central organ, which controls carbohydrate metabolism through maintaining glucose homeostasis by a tightly regulated system of genes or enzymes. The microRNAs are small non-coding RNAs playing an important role in the regulation of genes associated with developmental biology, physiology, metabolism, etc. Thus, in this study, we have intended to detect liver-specific microRNAs in farmed carp, Labeo bata, upon being fed a diet with different levels of carbohydrates. Here, we have conducted the experiment for 45 days using fingerlings of farmed carp fed with 20% (control), 40%, and 60% gelatinized starch levels. The liver tissues were collected from each treatment and processed for RNA isolation, small RNA library preparation, and high-throughput sequencing using Illumina NexSeq500. Through sequencing, 15,779,417 reads in 20% CHO, 13,959,039 in 40% CHO, and 13,661,950 in 60% CHO reads were generated for control and treated fishes using three small RNA libraries. We have investigated 445 novel and 231 conserved microRNAs in 20%, 40%, and 60% carbohydrate (CHO), respectively, through computational analysis. The differential expression analysis of miRNAs was carried out between different treatments compared with control and this study depicted 117 known and 114 novel miRNA genes involved in carbohydrate metabolic pathways. Further, target prediction and gene ontology analysis revealed that miRNAs were involved in several pathways such as signaling pathway, G protein pathway, complement receptor-mediated pathway, dopamine receptor signaling pathway, epidermal growth factor pathway, and notch signaling pathway. The predicted miRNA sites in targeted genes were associated with cellular activities, developmental biology, DNA binding, Golgi apparatus, extracellular region, catalytic activity, MAPK cascade, etc. Overall, we have generated a vital resource of liver-specific miRNAs involved in metabolic gene regulation. These studies further will help develop miRNA inhibitors to study their role during carbohydrate metabolism in farmed carp.

The functions and clinical application potential of exosomes derived from adipose mesenchymal stem cells: a comprehensive review

Exosomes are extracellular membranous nanovesicles that mediate local and systemic intercellular communication by transporting proteins or nucleic acids (DNA and RNA) into target cells, thus altering the behaviors of recipient cells. Recent studies have revealed that these vesicles play a critical role in many biological functions, such as cell proliferation, immune regulation, nerve regeneration, and cancer. Adipose-derived stem cells (ADSCs) are now considered a multipotent and abundant tool in the field of cell therapy and regenerative medicine. ADSCs can produce and secrete many exosomes, which inherit multiple functions of cells. Therefore, in this review, we will introduce the characteristics of exosomes derived from ADSCs (ADSC-Exos), describe their functions in different biological processes, summarize the latest research achievements, describe their limitations in cell-free therapy, and provide further insights into their clinical application potential for the treatment of certain diseases.

The contribution of miR-122 to the innate immunity by regulating toll-like receptor 4 in hepatoma cells

BACKGROUND

Hepatocellular carcinoma (HCC) is a kind of malignancies to impact human health. It has been reported that aberrant toll-like receptor (TLR) signaling may contribute to the development and progression of HCC, especially TLR4. MiR-122, which extensively involved in hepatitis virus infection and the apoptosis of hepatoma cells, might be decreased in HCC patients livers. The hypothesis of this study was whether miR-122 plays a role in inflammatory pathways through regulating TLR4 expression in hepatoma cells.

METHODS

The expression of miR-122 in the tissues of HCC patients compared to controls in TCGA datasets was analyzed. The relationship between miR-122 and TLR4 was detected in HCC cell lines by increasing/decreasing miR-122 expression. The target of miR-122 on TLR4 was confirmed by luciferase reporter assays. The proliferation of HCC cells and production of proinflammatory cytokines were measured with miR-122 upregulation and inhibition.

RESULTS

We found that the expression of miR-122 was decreased in HCC tissues and showed the diagnostic capacity for HCC in TCGA datasets. MiR-122 and TLR4 expression have negative correlation in normal liver cells and HCC cells. Upregulation of miR-122 significantly inhibited TLR4 expression in hepatoma cells, including in hepatoma cells with the induction of LPS, while knocking down miR-122 increased TLR4 expression. By screening potential miR-122 targets among TLR4, we found that there was a putative miR-122 target in TLR4 3'UTR. Mutations in the nt1603-nt1609 region of TLR4 3'UTR abandoned the impact of miR-122 on TLR4 expression. Over-expression/down-expression of miR-122 could influence the proliferation and the expression of natural immune factors.

CONCLUSIONS

MiR-122 might target TLR4 and regulate host innate immunity in hepatoma cells, which revealed a new molecular mechanism of miR-122 on the regulation of innate immunity.

The miR-873/NDFIP1 axis promotes hepatocellular carcinoma growth and metastasis through the AKT/mTOR-mediated Warburg effect

Hepatocellular carcinoma (HCC) progression depends on cellular metabolic reprogramming as both direct and indirect consequence of oncogenic lesions. However, the underlying mechanisms are still understood poorly. Here, we report that miR-873 promotes Warburg effect in HCC cells by increasing glucose uptake, extracellular acidification rate (ECAR), lactate production, and ATP generation, and decreasing oxygen consumption rate (OCR) in HCC cells. Mechanistically, we show that miR-873 activates the key glycolytic proteins AKT/mTOR via targeting NDFIP1 which triggers metabolic shift. We further demonstrate that enhanced glycolysis is essential for the role of miR-873 to drive HCC progression. By using immunohistochemistry analysis, we show a link between the aberrant expression of miR-873, NDFIP1, and phospho-AKT in clinical HCC samples. We also found that miR-873 was up-regulated by HIF1α, a critical glycolysis-related transcription factor. However, BAY 87-2243, a HIF1α specific inhibitor, blocks miR-873 mediated tumor growth and metastasis in nude mice. Collectively, our data uncover a previously unappreciated function of miR-873 in HCC cell metabolism and tumorigenesis, suggesting that targeting miR-873/NDFIP1 axis could be a potential therapeutic strategy for the treatment of HCC patients.

MicroRNA-122 supports robust innate immunity in hepatocytes by targeting the RTKs/STAT3 signaling pathway

MicroRNA-122 (miR-122) is the most abundant microRNA in hepatocytes and a central player in liver biology and disease. Herein, we report a previously unknown role for miR-122 in hepatocyte intrinsic innate immunity. Restoration of miR-122 levels in hepatoma cells markedly enhanced the activation of interferons (IFNs) in response to a variety of viral nucleic acids or simulations, especially in response to hepatitis C virus RNA and poly (I:C). Mechanistically, miR-122 downregulated the phosphorylation (Tyr705) of STAT3, thereby removing the negative regulation of STAT3 on IFN-signaling. STAT3 represses IFN expression by inhibiting interferon regulatory factor 1 (IRF1), whereas miR-122 targets MERTK, FGFR1 and IGF1R, three receptor tyrosine kinases (RTKs) that directly promote STAT3 phosphorylation. This work identifies a miR-122–RTKs/STAT3–IRF1–IFNs regulatory circuitry, which may play a pivotal role in regulating hepatocyte innate immunity. These findings renewed our knowledge of miR-122’s function and have important implications for the treatment of hepatitis viruses.

Determining consistent prognostic biomarkers of overall survival and vascular invasion in hepatocellular carcinoma

Background: Potential prognostic biomarker candidates for hepatocellular carcinoma (HCC) are abundant, but their generalizability is unexplored. We cross-validated markers of overall survival (OS) and vascular invasion in independent datasets. Methods: The literature search yielded 318 genes related to survival and 52 related to vascular invasion. Validation was performed in three datasets (RNA-seq, n = 371; Affymetrix arrays, n = 91; Illumina gene chips, n = 135) by uni- and multivariate Cox regression and Mann-Whitney U-test, separately for Asian and Caucasian patients. Results: One hundred and eighty biomarkers remained significant in Asian and 128 in Caucasian subjects at p < 0.05. After multiple testing correction BIRC5 (p = 1.9 × 10^-10), CDC20 (p = 2.5 × 10^-9) and PLK1 (p = 3 × 10^-9) endured as best performing genes in Asian patients; however, none remained significant in the Caucasian cohort. In a multivariate analysis, significance was reached by stage (p = 0.0018) and expression of CENPH (p = 0.0038) and CDK4 (p = 0.038). KIF18A was the only gene predicting vascular invasion in the Affymetrix and Illumina cohorts (p = 0.003 and p = 0.025, respectively). Conclusion: Overall, about half of biomarker candidates failed to retain prognostic value and none were better than stage predicting OS. Impact: Our results help to eliminate biomarkers with limited capability to predict OS and/or vascular invasion.

MiR-139-5p is associated with poor prognosis and regulates glycolysis by repressing PKM2 in gallbladder carcinoma

OBJECTIVES

Gallbladder carcinoma (GBC) is the most highly aggressive cancer of biliary tract, but effective therapeutics are lacking. Emerging evidence has unveiled that miR-139-5p is aberrantly downregulated in cancers, including GBC. However, the functions and mechanisms of miR-139-5p in GBC remain unclear.

MATERIALS AND METHODS

MiR-139-5p-overexpression was established in GBC cell lines, after which cell proliferation, migration, invasion, colony formation, and glucose metabolism were assayed in vitro. Subsequently, bioinformatics prediction and dual-luciferase reporter were performed to confirm that pyruvate kinase M2 (PKM2) was a direct target of miRNA-139-5p. Xenograft mouse models were applied to investigate the role of miR-139-5p in GBC tumourigenicity in vivo. In situ hybridization and immunohistochemical assays were performed to determine the relationships among miR-139-5p, PKM2 expression and clinical malignancies in GBC samples.

RESULTS

We found that miR-139-5p was substantially downregulated in GBC tissues. Low expression of miR-139-5p was significantly associated with poor clinical outcomes. GBC cell proliferation, migration, and invasion could be inhibited by overexpression of miR-139-5p either in vitro or in vivo. In addition, miR-139-5p overexpression could directly inhibit PKM2 expression and lead to suppression of glucose consumption, lactate production, and cellular ATP levels. Moreover, PKM2 was frequently upregulated in GBC and correlated with poor prognosis. Mechanistically, miRNA-139-5p inhibited cell proliferation, migration, and glycolysis in GBC, at least in part, by repressing PKM2.

CONCLUSIONS

These results demonstrated a novel role for miR-139-5p/PKM2 in GBC progression and provided potential prognostic predictors for GBC patients.

Modelling the impact of changes in the extracellular environment on the cytosolic free NAD+/NADH ratio during cell culture

Cancer cells depend on glucose metabolism via glycolysis as a primary energy source, despite the presence of oxygen and fully functioning mitochondria, in order to promote growth, proliferation and longevity. Glycolysis relies upon NAD⁺ to accept electrons in the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) reaction, linking the redox state of the cytosolic NAD⁺ pool to glycolytic rate. The free cytosolic NAD⁺/NADH ratio is involved in over 700 oxidoreductive enzymatic reactions and as such, the NAD⁺/NADH ratio is regarded as a metabolic readout of overall cellular redox state. Many experimental techniques that monitor or measure total NAD⁺ and NADH are unable to distinguish between protein-bound and unbound forms. Yet total NAD⁺/NADH measurements yield little information, since it is the free forms of NAD⁺ and NADH that determine the kinetic and thermodynamic influence of redox potential on glycolytic rate. Indirect estimations of free NAD⁺/NADH are based on the lactate/pyruvate (L/P) ratio at chemical equilibrium, but these measurements are often undermined by high lability. To elucidate the sensitivity of the free NAD⁺/NADH ratio to changes in extracellular substrate, an in silico model of hepatocarcinoma glycolysis was constructed and validated against in vitro data. Model simulations reveal that over experimentally relevant concentrations, changes in extracellular glucose and lactate concentration during routine cancer cell culture can lead to significant deviations in the NAD⁺/NADH ratio. Based on the principles of chemical equilibrium, the model provides a platform from which experimentally challenging situations may be examined, suggesting that extracellular substrates play an important role in cellular redox and bioenergetic homeostasis.

Long Non-Coding RNAs as Mediators of Tumor Microenvironment and Liver Cancer Cell Communication

The tumor microenvironment is an important concept that defines cancer development not only through tumor cells themselves but also the surrounding cellular and non-cellular components, including stromal cells, blood vessels, infiltrating inflammatory cells, cancer stem cells (CSC), cytokines, and growth factors, which act in concert to promote tumor cell survival and metastasis. Hepatocellular carcinoma (HCC) is one of the most common and aggressive human malignancies worldwide. Poor prognosis is largely attributable to the high rate of tumor metastasis, highlighting the importance of identifying patients at risk in advance and developing novel therapeutic targets to facilitate effective intervention. Long non-coding RNAs (lncRNA) are a class of non-protein coding transcripts longer than 200 nucleotides frequently dysregulated in various cancer types, which have multiple functions in widespread biological processes, including proliferation, apoptosis, metastasis, and metabolism. lncRNAs are involved in regulation of the tumor microenvironment and reciprocal signaling between cancer cells. Targeting of components of the tumor microenvironment or cancer cells has become a considerable focus of therapeutic research and establishing the effects of different lncRNAs on this network should aid in the development of effective treatment strategies. The current review provides a summary of the essential properties and functional roles of known lncRNAs associated with the tumor microenvironment in HCC.

Effects of PKM2 on global metabolic changes and prognosis in hepatocellular carcinoma: from gene expression to drug discovery

BACKGROUND

Hepatocellular carcinoma (HCC) is a malignant tumor that threatens global human health. High PKM2 expression is widely reported in multiple cancers, especially in HCC. This study aimed to explore the effects of PKM2 on global gene expression, metabolic damages, patient prognosis, and multiple transcriptional regulation relationships, as well as to identify several key metabolic genes and screen some small-molecule drugs.

METHODS

Transcriptome and clinical HCC data were downloaded from the NIH-GDC repository. Information regarding the metabolic genes and subsystems was collected from the Recon 2 human metabolic model. Drug-protein interaction data were obtained from the DrugBank and UniProt databases. We defined patients with PKM2 expression levels ≥11.25 as the high-PKM2 group, and those with low PKM2 expression (< 11.25) were defined as the low-PKM2 group.

RESULTS

The results showed that the global metabolic gene expression levels were obviously divided into the high- or low-PKM2 groups. In addition, a greater number of affected metabolic subsystems were observed in the high-PKM2 group. Furthermore, we identified 98 PKM2-correlated deregulated metabolic genes that were associated with poor overall patient survival. Together, these findings suggest more comprehensive influences of PKM2 on HCC. In addition, we screened several small-molecule drugs that target these metabolic enzymes, some of which have been used in antitumor clinical studies.

CONCLUSIONS

HCC patients with high PKM2 expression showed more severe metabolic damage, transcriptional regulation imbalance and poor prognosis than low-PKM2 individuals. We believe that our study provides valuable information for pathology research and drug development for HCC.

MiR-545-3p/MT1M axis regulates cell proliferation, invasion and migration in hepatocellular carcinoma

Studies have shown that metallothionein 1 M (MT1M) is a tumor suppressor gene which is frequently down-regulated in human hepatocellular carcinoma (HCC). The methylation of MT1M promoter region is one of the important transcriptional regulation mechanisms that contribute to the loss of its expression. In our study, we found that there are still half of the 55 HCC tumor tissues in our cohort do not share the promoter methylation of MT1M. So, we speculated there maybe another mechanism participating in the downregulation of MT1M in HCC. Then, we provided evidences that miR-545-3p, which served as a tumor promoter, post-transcriptionally regulate MT1M in HCC through binding to its untranslated region (3'UTR). Taking together, we investigated the role of miR-545-3p in the process of HCC through regulating MT1M.

rs61991156 in miR-379 is associated with low capability of glycolysis of gastric cancer by enhanced regulation of PKM2

Background

Glycolysis is an important metabolic oncogenic change also play a pivot role in the Warburg effect. Glycolysis related gene PKM2 expressed differently individually. Presently, we sought to investigate the effect of single nucleotide polymorphism (SNP) at rs61991156 of miR-379 on gastric cancer (GC) proliferation and metabolism.

Methods

The genotype of rs61991156 in miR-379 was investigated by using real-time PCR. The glycolysis-related metabolites were determined by using GC–TOF–MS. The biological effects of rs61991156 in miR-379 was explored by in vitro studies.

Results

In this study, we found that rs61991156 in miR-379 was involved in the occurrence of GC by acting on the 3′UTR region of PKM2. The clinical data analysis revealed that A > G in rs187960998 was significantly associated with better differentiation, small tumor size, and non-metastasis. In vitro study further revealed that A > G SNP of miR-379 could decrease GC cell proliferation as well as the promoter activity and expression of PKM2. The glycolysis of the patients with miR-379 GG genotype was significantly lower than AG and AA genotype by metabolomics analysis. The patients with AA genotype have significantly lower PKM2 expression compared to the G carrier, while there is no significant expression difference in miR-379 expression. Patients with AA genotype have significantly shorter survival rate compared to the G carrier.

Conclusion

rs61991156 in miR-379 was highly associated with a decreased risk, well differentiation and better post-surgery survival in Chinese population by inhibiting the expression of PKM2.

Electronic supplementary material

The online version of this article (10.1186/s12935-018-0593-0) contains supplementary material, which is available to authorized users.

The role of miR-122 in the dysregulation of glucose-6-phosphate dehydrogenase (G6PD) expression in hepatocellular cancer

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related deaths worldwide. Thus, a better understanding of molecular aberrations involved in HCC pathogenesis is necessary for developing effective therapy. It is well established that cancer cells metabolize energy sources differently to rapidly generate biomass. Glucose-6-phosphate-dehydrogenase (G6PD), the rate-limiting enzyme of the Pentose Phosphate Pathway (PPP), is often activated in human malignancies to generate precursors for nucleotide and lipid synthesis. Here, we determined the clinical significance of G6PD in primary human HCC by analyzing RNA-seq and clinical data in The Cancer Genome Atlas. We found that the upregulation of G6PD correlates with higher tumor grade, increased tumor recurrence, and poor patient survival. Notably, liver-specific miR-122, which is essential for metabolic homeostasis, suppresses G6PD expression by directly interacting with its 3'UTR. Luciferase reporter assay confirmed two conserved functional miR-122 binding sites located in the 3'-UTR of G6PD. Furthermore, we show that ectopic expression of miR-122 and miR-1, a known regulator of G6PD expression coordinately repress G6PD expression in HCC cells. These miRNAs also reduced G6PD activity in HepG2 cells that express relatively high activity of this enzyme. Collectively, this study provides evidence that anti-HCC efficacy of miR122 and miR-1 could be mediated, at least in part, through inhibition of PPP by suppressing the expression of G6PD.

Small but Heavy Role: MicroRNAs in Hepatocellular Carcinoma Progression

Hepatocellular carcinoma (HCC), which accounts for 85-90% of primary liver cancer, is the fifth most common malignant tumor and the third leading cause of cancer-related deaths worldwide, but the pathological mechanism of HCC is still not fully elucidated. miRNAs are evolutionarily endogenous small noncoding RNAs that negatively regulate gene expression via posttranscriptional inhibition or target mRNA degradation in several diseases, especially human cancer. Therefore, discovering the roles of miRNAs is appealing to scientific researchers. Emerging evidence has shown that the aberrant expressions of numerous miRNAs are involved in many HCC biological processes. In hepatocarcinogenesis, miRNAs with dysregulated expression can exert their function as oncogenes or tumor suppressors depending on their cellular target during the cell cycle, and in tumor development, differentiation, apoptosis, angiogenesis, metastasis, and progression of the tumor microenvironment. In this review, we summarize current findings on miRNAs and assess their functions to explore the molecular mechanisms of tumor progression in HCC.