Low levels of pyruvate induced by a positive feedback loop protects cholangiocarcinoma cells from apoptosis

Rare diseases and pyruvate kinase M2: a promising therapeutic connection

Pyruvate kinase M2 (PKM2) is a key glycolytic enzyme that regulates proliferating cell metabolism. The role of PKM2 in common diseases has been well established, but its role in rare diseases (RDs) is less understood. Over the past few years, PKM2 has emerged as a crucial player in RDs, including, neoplastic, respiratory, metabolic, and neurological disorders. Herein, we summarize recent findings and developments highlighting PKM2 as an emerging key player in RDs. We also discuss the current status of PKM2 modulation in RDs with particular emphasis on preclinical and clinical studies in addition to current challenges in the field.

Acetylation of c-Myc at Lysine 148 Protects Neurons After Ischemia

This study focuses on understanding the role of c-Myc, a cancer-associated transcription factor, in the penumbra following ischemic stroke. While its involvement in cell death and survival is recognized, its post-translational modifications, particularly acetylation, remain understudied in ischemia models. Investigating these modifications could have significant clinical implications for controlling c-Myc activity in the central nervous system. Although previous studies on c-Myc acetylation have been limited to non-neuronal cells, our research examines its expression in perifocal cells during stroke recovery to explore regulatory mechanisms via acetylation. We found that in peri-infarct neurons, c-Myc is upregulated with acetylation at K148 but not K323 during the acute phase of stroke, with SIRT2 deacetylase primarily affecting K148 acetylation. Molecular dynamics simulations suggest that lysine 148 plays a crucial role in stabilizing c-Myc spatial structure. Increased acetylation at K148 reduces c-Myc compaction, potentially limiting its nuclear penetration, promoting calpain-mediated cleavage, and decreasing nuclear localization. Additionally, cytoplasmic acetylation at K148 may alter c-Myc's interaction with unidentified proteins, potentially influencing its pro-apoptotic effects and promoting cytoplasmic accumulation. Targeting SIRT2 with selective inhibitors could be a promising avenue for future stroke therapy strategies.

BCLAF1 is Expressed as a Potential Anti-oncogene in Bile Duct Cancer

Validating the role of BCLAF1 in the development of Bile Duct Cancer. Differential expression of BCLAF1 in Bile Duct Cancer and normal tissues was analyzed bioinformatically, and immuno-infiltration analysis was performed by R. We also derived the correlation between the expression of BCLAF1 and HIF-1α by bioinformatics analysis and validated it by Western Blotting, qRT-PCR and scratch assays before and after hypoxia. Through bioinformatics analysis, we found that BCLAF1 mRNA was significantly higher in the tumor tissues of Bile Duct Cancer. The high expression of BCLAF1 implied a more advanced stage but a lower mortality rate. KEGG and GO enrichment analysis showed that BCLAF1 overexpression in Bile Duct Cancer was mainly associated with histone modification, peptidyl lysine modification, and macromolecular methylation. We used the TIMER algorithm to show that BCLAF1 expression in Bile Duct Cancer is associated with immune cell infiltration, which affects tumor progression and patient prognosis. We confirmed by normoxia and hypoxia qRT-PCR, Western Blotting and scratch assays that BCLAF1 and HIF-1α expression are positively correlated and that BCLAF1 may be expressed as anti-oncogene in Bile Duct Cancer. These findings demonstrate that BCLAF1 may act as anti-oncogene in Bile Duct Cancer and may be involved in immune cell infiltration in Bile Duct Cancer, suppressing the expression of HIF-1α.

The roles of epigenetic regulation in cholangiocarcinogenesis

Cholangiocarcinoma (CCA), a heterogeneous malignancy of bile duct epithelial cells, is characterized by aggressiveness, difficult diagnosis, and poor prognosis due to limited understanding and lack of effective therapeutic strategies. Genetic and epigenetic alterations accumulated in CCA cells can cause the aberrant regulation of oncogenes and tumor suppressors. Epigenetic alterations with histone modification, DNA methylation, and noncoding RNA modulation are associated with the carcinogenesis of CCA. Mutation or silencing of genes by various mechanisms can be a frequent event during CCA development. Alterations in histone acetylation/deacetylation at the posttranslational level, DNA methylation at promoters, and noncoding RNA regulation contribute to the heterogeneity of CCA and drive tumor development. In this review article, we mainly focus on the roles of epigenetic regulation in cholangiocarcinogenesis. Alterations in epigenetic modification can be potential targets for the therapeutic management of CCA, and epigenetic targets may become diagnostic biomarkers of CCA.

Impact of Opioids on Cellular Metabolism: Implications for Metabolic Pathways Involved in Cancer

Opioid utilization for pain management is prevalent among cancer patients. There is significant evidence describing the many effects of opioids on cancer development. Despite the pivotal role of metabolic reprogramming in facilitating cancer growth and metastasis, the specific impact of opioids on crucial oncogenic metabolic pathways remains inadequately investigated. This review provides an understanding of the current research on opioid-mediated changes to cellular metabolic pathways crucial for oncogenesis, including glycolysis, the tricarboxylic acid cycle, glutaminolysis, and oxidative phosphorylation (OXPHOS). The existing literature suggests that opioids affect energy production pathways via increasing intracellular glucose levels, increasing the production of lactic acid, and reducing ATP levels through impediment of OXPHOS. Opioids modulate pathways involved in redox balance which may allow cancer cells to overcome ROS-mediated apoptotic signaling. The majority of studies have been conducted in healthy tissue with a predominant focus on neuronal cells. To comprehensively understand the impact of opioids on metabolic pathways critical to cancer progression, research must extend beyond healthy tissue and encompass patient-derived cancer tissue, allowing for a better understanding in the context of the metabolic reprogramming already undergone by cancer cells. The current literature is limited by a lack of direct experimentation exploring opioid-induced changes to cancer metabolism as they relate to tumor growth and patient outcome.

Glycolysis in Chronic Liver Diseases: Mechanistic Insights and Therapeutic Opportunities

Chronic liver diseases (CLDs) cover a spectrum of liver diseases, ranging from nonalcoholic fatty liver disease to liver cancer, representing a growing epidemic worldwide with high unmet medical needs. Glycolysis is a conservative and rigorous process that converts glucose into pyruvate and sustains cells with the energy and intermediate products required for diverse biological activities. However, abnormalities in glycolytic flux during CLD development accelerate the disease progression. Aerobic glycolysis is a hallmark of liver cancer and is responsible for a broad range of oncogenic functions including proliferation, invasion, metastasis, angiogenesis, immune escape, and drug resistance. Recently, the non-neoplastic role of aerobic glycolysis in immune activation and inflammatory disorders, especially CLD, has attracted increasing attention. Several key mediators of aerobic glycolysis, including HIF-1α and pyruvate kinase M2 (PKM2), are upregulated during steatohepatitis and liver fibrosis. The pharmacological inhibition or ablation of PKM2 effectively attenuates hepatic inflammation and CLD progression. In this review, we particularly focused on the glycolytic and non-glycolytic roles of PKM2 in the progression of CLD, highlighting the translational potential of a glycolysis-centric therapeutic approach in combating CLD.

The Role of Post-Translational Acetylation and Deacetylation of Signaling Proteins and Transcription Factors after Cerebral Ischemia: Facts and Hypotheses

Histone deacetylase (HDAC) and histone acetyltransferase (HAT) regulate transcription and the most important functions of cells by acetylating/deacetylating histones and non-histone proteins. These proteins are involved in cell survival and death, replication, DNA repair, the cell cycle, and cell responses to stress and aging. HDAC/HAT balance in cells affects gene expression and cell signaling. There are very few studies on the effects of stroke on non-histone protein acetylation/deacetylation in brain cells. HDAC inhibitors have been shown to be effective in protecting the brain from ischemic damage. However, the role of different HDAC isoforms in the survival and death of brain cells after stroke is still controversial. HAT/HDAC activity depends on the acetylation site and the acetylation/deacetylation of the main proteins (c-Myc, E2F1, p53, ERK1/2, Akt) considered in this review, that are involved in the regulation of cell fate decisions. Our review aims to analyze the possible role of the acetylation/deacetylation of transcription factors and signaling proteins involved in the regulation of survival and death in cerebral ischemia.

Metabolic Constants and Plasticity of Cancer Cells in a Limiting Glucose and Glutamine Microenvironment-A Pyruvate Perspective

The metabolism of cancer cells is an issue of dealing with fluctuating and limiting levels of nutrients in a precarious microenvironment to ensure their vitality and propagation. Glucose and glutamine are central metabolites for catabolic and anabolic metabolism, which is in the limelight of numerous diagnostic methods and therapeutic targeting. Understanding tumor metabolism in conditions of nutrient depletion is important for such applications and for interpreting the readouts. To exemplify the metabolic network of tumor cells in a model system, the fate ¹³C₆-glucose was tracked in a breast cancer cell line growing in variable low glucose/low glutamine conditions. ¹³C-glucose-derived metabolites allowed to deduce the engagement of metabolic pathways, namely glycolysis, the TCA-cycle including glutamine and pyruvate anaplerosis, amino acid synthesis (serine, glycine, aspartate, glutamate), gluconeogenesis, and pyruvate replenishment. While the metabolic program did not change, limiting glucose and glutamine supply reduced cellular metabolite levels and enhanced pyruvate recycling as well as pyruvate carboxylation for entry into the TCA-cycle. Otherwise, the same metabolic pathways, including gluconeogenesis, were similarly engaged with physiologically saturating as with limiting glucose and glutamine. Therefore, the metabolic plasticity in precarious nutritional microenvironment does not require metabolic reprogramming, but is based on dynamic changes in metabolite quantity, reaction rates, and directions of the existing metabolic network.

The extracellular lactate-to-pyruvate ratio modulates the sensitivity to oxidative stress-induced apoptosis via the cytosolic NADH/NAD+ redox state

The advantages of the Warburg effect on tumor growth and progression are well recognized. However, the relevance of the Warburg effect for the inherent resistance to apoptosis of cancer cells has received much less attention. Here, we show here that the Warburg effect modulates the extracellular lactate-to-pyruvate ratio, which profoundly regulates the sensitivity towards apoptosis induced by oxidative stress in several cell lines. To induce oxidative stress, we used the rapid apoptosis inducer Raptinal. We observed that medium conditioned by HepG2 cells has a high lactate-to-pyruvate ratio and confers resistance to Raptinal-induced apoptosis. In addition, imposing a high extracellular lactate-to-pyruvate ratio in media reduces the cytosolic NADH/NAD⁺ redox state and protects against Raptinal-induced apoptosis. Conversely, a low extracellular lactate-to-pyruvate ratio oxidizes the cytosolic NADH/NAD⁺ redox state and sensitizes HepG2 cells to oxidative stress-induced apoptosis. Mechanistically, a high extracellular lactate-to-pyruvate ratio decreases the activation of JNK and Bax under oxidative stress, thereby inhibiting the intrinsic apoptotic pathway. Our observations demonstrate that the Warburg effect of cancer cells generates an anti-apoptotic extracellular environment by elevating the extracellular lactate-to-pyruvate ratio which desensitizes cancer cells towards apoptotic insults. Consequently, our study suggests that the Warburg effect can be targeted to reverse the lactate-to-pyruvate ratios in the tumor microenvironment and thereby re-sensitize cancer cells to oxidative stress-inducing therapies.

Omics-Based Platforms: Current Status and Potential Use for Cholangiocarcinoma

Cholangiocarcinoma (CCA) has been identified as a highly malignant cancer that can be transformed from epithelial cells of the bile duct, including intrahepatic, perihilar and extrahepatic. High-resolution imaging tools (abdominal ultrasound, computed tomography and percutaneous transhepatic cholangial drainage) are recruited for diagnosis. However, the lack of early diagnostic biomarkers and treatment evaluation can lead to serious outcomes and poor prognosis (i.e., CA19-9, MUC5AC). In recent years, scientists have established a large number of omics profiles to reveal underlying mechanisms and networks (i.e., IL-6/STAT3, NOTCH). With these results, we achieved several genomic alteration events (i.e., TP53_mut, KRAS_mut) and epigenetic modifications (i.e., DNA methylation, histone modification) in CCA cells and clinical patients. Moreover, we reviewed candidate gene (such as NF-kB, YAP1) that drive gene transcription factors and canonical pathways through transcriptomics profiles (including microarrays and next-generation sequencing). In addition, the proteomics database also indicates which molecules and their directly binding status could trigger dysfunction signatures in tumorigenesis (carbohydrate antigen 19-9, mucins). Most importantly, we collected metabolomics datasets and pivotal metabolites. These results reflect the pharmacotherapeutic options and evaluate pharmacokinetic/pharmacodynamics in vitro and in vivo. We reversed the panels and selected many potentially small compounds from the connectivity map and L1000CDS² system. In this paper, we summarize the prognostic value of each candidate gene and correlate this information with clinical events in CCA. This review can serve as a reference for further research to clearly investigate the complex characteristics of CCA, which may lead to better prognosis, drug repurposing and treatment strategies.

Role of Glucose Metabolism Reprogramming in the Pathogenesis of Cholangiocarcinoma

Cholangiocarcinoma (CCA) is one of the most lethal cancers, and its rate of occurrence is increasing annually. The diagnoses of CCA patients remain elusive due to the lack of early symptoms and is misdiagnosed as HCC in a considerable percentage of patients. It is crucial to explore the underlying mechanisms of CCA carcinogenesis and development to find out specific biomarkers for early diagnosis of CCA and new promising therapeutic targets. In recent times, the reprogramming of tumor cells metabolism has been recognized as a hallmark of cancer. The modification from the oxidative phosphorylation metabolic pathway to the glycolysis pathway in CCA meets the demands of cancer cell proliferation and provides a favorable environment for tumor development. The alteration of metabolic programming in cancer cells is complex and may occur via mutations and epigenetic modifications within oncogenes, tumor suppressor genes, signaling pathways, and glycolytic enzymes. Herein we review the altered metabolism in cancer and the signaling pathways involved in this phenomena as they may affect CCA development. Understanding the regulatory pathways of glucose metabolism such as Akt/mTOR, HIF1α, and cMyc in CCA may further develop our knowledge of this devastating disease and may offer relevant information in the exploration of new diagnostic biomarkers and targeted therapeutic approaches for CCA.

Multifaceted Aspects of Metabolic Plasticity in Human Cholangiocarcinoma: An Overview of Current Perspectives

Cholangiocarcinoma (CCA) is a deadly tumor without an effective therapy. Unique metabolic and bioenergetics features are important hallmarks of tumor cells. Metabolic plasticity allows cancer cells to survive in poor nutrient environments and maximize cell growth by sustaining survival, proliferation, and metastasis. In recent years, an increasing number of studies have shown that specific signaling networks contribute to malignant tumor onset by reprogramming metabolic traits. Several evidences demonstrate that numerous metabolic mediators represent key-players of CCA progression by regulating many signaling pathways. Besides the well-known Warburg effect, several other different pathways involving carbohydrates, proteins, lipids, and nucleic acids metabolism are altered in CCA. The goal of this review is to highlight the main metabolic processes involved in the cholangio-carcinogeneis that might be considered as potential novel druggable candidates for this disease.