P53 regulates glucose metabolic reprogramming in MASLD-related hepatocellular carcinoma via modulating mitochondrial pyruvate carriers.

Mitochondrial pyruvate carrier 1 (MPC1) is a key metabolic protein that regulates the transport of pyruvate into the mitochondrial inner membrane. MPC1 deficiency may cause metabolic reprogramming. However, whether and how MPC1 controls mitochondrial oxidative capacity in cancer are still relatively unknown. MPC1 deficiency was recently found to be strongly associated with various diseases and cancer hallmarks. We utilized online databases and uncovered that MPC1 expression is lower in many cancer tissues than in adjacent normal tissues. In addition, MPC1 expression was found to be substantially altered in five cancer types: breast-invasive carcinoma (BRCA), kidney renal clear cell carcinoma (KIRC), lung adenocarcinoma (LUAD), pancreatic adenocarcinoma (PAAD), and prostate adenocarcinoma (PRAD). However, in KIRC, LUAD, PAAD, and PRAD, high MPC1 expression is closely associated with favourable prognosis. Low MPC1 expression in BRCA is significantly associated with shorter overall survival time. MPC1 expression shows strong positive and negative correlations with immune cell infiltration in thymoma (THYM) and thyroid carcinoma (THCA). Furthermore, we have comprehensively summarized the current literature regarding the metabolic reprogramming effects of MPC1 in various cancers. As shown in the literature, MPC1 expression is significantly decreased in cancer tissue and associated with poor prognosis. We discuss the potential metabolism-altering effects of MPC1 in cancer, including decreased pyruvate transport ability; impaired pyruvate-driven oxidative phosphorylation (OXPHOS); and increased lactate production, glucose consumption, and glycolytic capacity, and the underlying mechanisms. These activities facilitate tumour progression, migration, and invasion. MPC1 is a novel cancer biomarker and potentially powerful therapeutic target for cancer diagnosis and treatment. Further studies aimed at slowing cancer progression are in progress.

Hepatocellular carcinoma (HCC) is prevalent globally, and the discovery of new targets is vital for the treatment of HCC. Mitochondrial pyruvate carrier 1 (MPC1) has been found to exhibit reduced expression and promote tumour progression in some cancers, although its role in HCC needs to be explored. Using GEO datasets and Kaplan‒Meier plotter, the clinicopathological features and patient prognosis were analysed by assessing the expression levels of MPC1 in HCC tissues. After MPC1-knockdown and MPC1-overexpressing cell lines were constructed, the effects of modulating MPC1 expression on the malignant phenotype of HCC cells were tested via CCK8, colony formation, and scratch assays and flow cytometry. The effects of MPC1 on HCC cells and mitochondria were examined via MitoTracker Red CMXRos staining, cytoskeleton staining and cellular energy metabolism assays. MPC1 expression was found to be reduced in HCC patients and correlated with prognosis and clinicopathological features. It was found that low expression of MPC1 promotes the malignant phenotype of HCC cells and affects the mitochondrial energy metabolism of HCC cells to support the tumour microenvironment, and that MPC1 may act through signal transducer and activator of transcription 3 (STAT3). MPC1 might play a tumor-suppressing role in HCC through its interaction with STAT3, and this discovery could offer novel perspectives for HCC treatment.

Hepatocellular carcinoma (HCC) is a devastating disease with an incidence-to-mortality ratio near 1, making primary prevention the goal of treatment. With the growth of the global obesity epidemic, HCC is increasingly being driven by non-alcoholic fatty liver disease (NAFLD). Disruption of the liver Mitochondrial Pyruvate Carrier (MPC) in mice attenuates NAFLD disease severity. Indeed, currently, MPC inhibitors are in clinical trial for treatment of NAFLD. Given that MPC disruption attenuated NAFLD disease severity and that NAFLD disease progression causes HCC, we asked the question of whether MPC disruption would prevent HCC. We found that liver MPC protein levels increased in response to diet-induced obesity. We found that MPC transcript expression among human cancers to be greatest in HCC. We employed a N-nitrosodiethylamine plus carbon tetrachloride model of HCC in WT and MPC liver-specific knockout mice (LivKO) to test whether MPC disruption diminished liver tumor development. Liver MPC disruption decreased tumor burden and size. Transcriptomic profiling revealed downregulation of glutathione metabolism as a distinguishing feature of MPC LivKO tumors. MPC disruption and glutathione depletion were synthetically lethal in cultured hepatomas. Stable isotope tracing showed that hepatocyte MPC disruption increased glutamine flux into the TCA cycle away from glutathione synthesis. Our results suggest that MPC disruption might be a useful HCC treatment strategy by blunting a key component of cancer progression, glutathione metabolism.

Pancreatic ductal adenocarcinoma (PDAC) can be stratified into distinct transcriptome subtypes, with the ‘basal-like’ or ‘squamous’ subtype being associated with worse prognosis, compared to the ‘classical’ subtype. Our group recently demonstrated that PDAC tumors have unique metabolic transcriptome profiles, and that genes involved in glycolysis and cholesterol synthesis pathways are positively correlated with basal-like and classical gene expression patterns, respectively. The mitochondrial pyruvate complex (MPC) mediates the transport of pyruvate into the mitochondria which attenuates the effect of glycolysis on tumor progression. The mitochondrial pyruvate carrier 1 (MPC1) gene, which encodes one of two subunits of MPC, is deleted in over 60% of metastatic PDAC and PDAC glycolytic tumors have lowest levels of MPC1 expression. Using PDAC tissue microarrays, we also found that reduced MPC1 protein expression correlates with reduced survival in patients. We hypothesized that targeting MPC1 will alter metabolic reprogramming and may modulate tumor aggressiveness and therapeutic vulnerability in PDAC tumor cells. Genomically and clinically annotated patient-derived tumor organoids (PDOs) were generated from metastatic biopsies from patients enrolled in the PanGen study (NCT02869802). PDOs from both basal and classical tumors were used in the study. In order to investigate glycolysis in PDOs, we adapted the Seahorse Glycolytic Stress Test. Glycolysis, glycolytic capacity and reserve were analyzed in PDOs under basal and treated conditions. To alter MPC1 activity, PDOs were treated for 48 hours with 5uM of UK-5099, an MPC1 inhibitor, or 2.5-5uM SRT1720. SRT1720 is an activator of sirtuin 1 (SIRT1) and the transcriptional coactivator peroxisome proliferator-activated receptor γ coactivator-1α (PGC1-α), which regulates the expression of MPC1. An unpaired t-test with an alpha of 0.05 was used for all statistical analysis. Glycolysis analysis revealed distinct glycolytic profiles in PDOs with differences in glycolytic capacity and reserves trending with different tumor subtypes. Treatment with UK-5099 resulted in an increase in both glycolytic rate and reserve in PDOs from basal and classical tumors. Treatment with SRT1720 resulted in significantly reduced glycolytic rate and capacity. These data suggest that PDAC PDOs exhibit distinct metabolic profiles and that targeting MPC1 can modulate glycolysis in PDOs. Our ongoing efforts aim to further characterize the subtype-specific effect of MPC1 modulators on glycolysis and chemotherapy response in PDAC PDOs. Citation Format: Hassan A. Ali, Andrew Metcalfe, James T. Topham, Cassia S. Warren, Joanna M. Karasinska, David F. Schaeffer, Daniel J. Renouf. Targeting the mitochondrial pyruvate complex to alter metabolic programming in pancreatic cancer [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2021 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2021;81(22 Suppl):Abstract nr PO-021.

Abnormal mitochondrial pyruvate carrier 1 (MPC1) expression plays a key role in tumor metabolic reprogramming and progression. Understanding its significance in non-small cell lung cancer (NSCLC) is crucial for identifying therapeutic targets. TIMER 2.0 was utilized to assess the expression of MPC1 in both normal and cancer tissues in pan-cancer. Overall survival (OS) differences between high and low MPC1 expression were analyzed in NSCLC using the Cancer Genome Atlas (TCGA) datasets. We also examined the expression of MPC1 in NSCLC cell lines using western blotting and quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). In addition, the tissue samples and clinical information of 80 patients with NSCLC from our hospital were collected. Immunohistochemistry (IHC) was used to assess MPC1 expression, and OS was evaluated using Kaplan-Meier curves and the log-rank test. Univariate and multivariate Cox regression analyses were conducted to evaluate the prognostic values of the clinical characteristics and MPC1expression. Analysis of public databases suggested that MPC1 was downregulated in NSCLC compared to that in normal lung tissue and predicted poor prognosis. In addition, the expression of MPC1 in NSCLC cell lines was lower than that in human bronchial epithelial (HBE) cells at both protein and mRNA levels. Further clinical analysis suggested that MPC1 expression was correlated with age, tumor T stage, and TNM stage. Kaplan-Meier analysis revealed that NSCLC patients with high MPC1 expression had a better prognosis, particularly in lung adenocarcinoma (LUAD), whereas no survival benefit was observed in lung squamous cell carcinoma (LUSC). Univariate and multivariate analyses suggested that MPC1 was an independent prognostic factor for patients with NSCLC. MPC1 is poorly expressed in NSCLC, particularly in LUAD, which predicts a poor prognosis and may serve as an independent prognostic factor. Further studies on MPC1 may reveal new targets for the treatment of NSCLC.

The nucleotide-binding and oligomerization domain, leucine-rich repeats, and pyrin domain-containing protein 3 (NLRP3) inflammasome plays a crucial role in innate immunity and is involved in the pathogenesis of autoinflammatory diseases. Glycolysis regulates NLRP3 inflammasome activation in macrophages. However, how lactic acid fermentation and pyruvate oxidation controlled by the mitochondrial pyruvate carrier (MPC) affect NLRP3 inflammasome activation and autoinflammatory disease remains elusive. We found that the inactivation of MPC with genetic depletion or pharmacological inhibitors, MSDC-0160 or pioglitazone, increased NLRP3 inflammasome activation and IL-1β secretion in macrophages. Glycolytic reprogramming induced by MPC inhibition skewed mitochondrial ATP-associated oxygen consumption into cytosolic lactate production, which enhanced NLRP3 inflammasome activation in response to monosodium urate (MSU) crystals. As pioglitazone is an insulin sens MSDC-itizer used for diabetes, its MPC inhibitory effect in diabetic individuals was investigated. The results showed that MPC inhibition exacerbated MSU-induced peritonitis in diabetic mice and increased the risk of gout in patients with diabetes. Altogether, we found that glycolysis controlled by MPC regulated NLRP3 inflammasome activation and gout development. Accordingly, prescriptions for medications targeting MPC should consider the increased risk of NLRP3-related autoinflammatory diseases.

Diffuse Large B-Cell Lymphoma (DLBCL) is an aggressive form of non-Hodgkin lymphoma with heterogeneous molecular characteristics. Altered metabolism, particularly mitochondrial function, has emerged as a critical factor in cancer progression. However, the role of mitochondrial metabolism in DLBCL remains poorly understood. This study aimed to identify key mitochondrial factors associated with DLBCL progression. We analyzed transcriptomic data from multiple DLBCL datasets (GSE83632, TCGA-GTEX, GSE181063, GSE4475) using differential expression analysis, weighted gene co-expression network analysis (WGCNA), and Gene Set Enrichment Analysis (GSEA). The expression and function of the identified key factor, Mitochondrial Pyruvate Carrier 2 (MPC2), were validated using clinical samples, DLBCL cell lines, and an in vivo mouse model of xenograft. Integrative bioinformatics analysis identified MPC2 as a significantly upregulated gene in DLBCL, associated with enrichment of oxidative phosphorylation (OXPHOS) and cell cycle-related genes. MPC2 overexpression was confirmed in clinical DLBCL samples and cell lines at both mRNA and protein levels. Knockdown of MPC2 in DLBCL cells impaired mitochondrial OXPHOS, increased glycolysis, and suppressed cell proliferation, invasion, and 3D spheroid formation. In vivo, MPC2 silencing significantly reduced tumor growth in a xenograft mouse model. Our findings reveal MPC2 as a key regulator of mitochondrial function in DLBCL, promoting tumor progression through enhanced OXPHOS. This study provides new insights into the metabolic reprogramming of DLBCL and suggests MPC2 as a potential therapeutic target for this aggressive lymphoma.

More than 18 million adults in the United States abuse alcohol, a prevalence 5 times higher than that of hepatitis C. Chronic alcohol use of greater than 80 g/day for more than 10 years increases the risk for hepatocellular carcinoma (HCC) approximately 5-fold; alcohol use of less than 80 g/day is associated with a nonsignificant increased risk for HCC. The risk for HCC in decompensated alcohol induced cirrhosis approaches 1% per year. The risk does not decrease with abstinence, and HCC can occur in a noncirrhotic liver. Alcohol use in chronic hepatitis C doubles the risk for HCC as compared with the risk in hepatitis C alone. Furthermore, there may be synergism between alcohol and hepatitis C in the development of HCC, and in these patients HCC may occur at an earlier age and the HCC may be histologically more advanced. Studies in the United States and Italy suggest that alcohol is the most common cause of HCC (accounting for 32%-45% of HCC). The mechanisms by which alcohol causes HCC are incompletely understood, but may include chromosomal loss, oxidative stress, a decreased retinoic acid level in the liver, altered DNA methylation, and genetic susceptibility. Alcohol use is increasing in many countries, suggesting that alcohol will continue to be a common cause of HCC throughout the world.

In the realm of cellular biochemistry, mitochondria have been increasingly recognized for their critical role in both cellular metabolism and the etiology of various diseases. Mitochondrial transporters (MTs) are essential for maintaining cellular energy dynamics and metabolic fluxes by facilitating the bidirectional transfer of metabolites across mitochondrial membranes. Dysregulation of these transporters, such as the mitochondrial pyruvate carrier (MPC), citrate carrier (SLC25A1), and voltage-dependent anion channel (VDAC), disrupts energy metabolism, redox balance, and cellular signaling, contributing to the pathogenesis of neurodegenerative diseases (NDDs), cardiovascular diseases (CVDs), type 2 diabetes (T2D), and cancer. In NDDs, impaired transporters exacerbate oxidative stress and neuronal death, while in CVDs, they lead to energy deficits and heart failure. In T2D, dysfunctional transporters like MPC and carnitine palmitoyltransferase (CPT) systems drive insulin resistance and metabolic dysregulation. In cancer, upregulated transporters such as citrate carrier (SLC25A1), and dicarboxylate carrier (SLC25A10) as well as metabolic shifts like the Warburg effect support tumor growth and survival. Targeting MTs and metabolic reprogramming (MR) offers significant therapeutic potential. Preclinical studies have demonstrated the efficacy of mitochondrial-targeted therapies (MTT), such as adenosine monophosphate-activated protein kinase (AMPK) activators and antioxidants, in restoring metabolic homeostasis and reducing disease pathology. In cancer, inhibitors of glutamine transporters and VDAC1 are being explored to disrupt tumor metabolism. Several therapies are advancing to clinical trials, including mitochondrial-targeted drugs for NDDs and metabolic modulators for T2D and cancer, highlighting their translational potential. Despite notable individual achievements and isolated reviews in this field, there remains a lack of comprehensive syntheses that integrate these advancements. This review seeks to combine the prevailing scientific evidence and outline prospective research trajectories. The gathered data robustly support the significant potential of targeting MTs as a groundbreaking approach in the treatment of complex diseases, with the potential to significantly improve health outcomes and mitigate disease progression.Graphical abstract

JX06, a Novel PDK1 Inhibitor, Induces Myeloma Cell Apoptosis By Metabolic Reprogramming and Works Synergistically with Bortezomib

Axon regeneration is substantially regulated by gene expression and cytoskeleton remodeling. Here we show that the tumor suppressor protein p53 is required for neurite outgrowth in cultured cells including primary neurons as well as for axonal regeneration in mice. These effects are mediated by two newly identified p53 transcriptional targets, the actin-binding protein Coronin 1b and the GTPase Rab13, both of which associate with the cytoskeleton and regulate neurite outgrowth. We also demonstrate that acetylation of lysine 320 (K320) of p53 is specifically involved in the promotion of neurite outgrowth and in the regulation of the expression of Coronin 1b and Rab13. Thus, in addition to its recognized role in neuronal apoptosis, surprisingly, p53 is required for neurite outgrowth and axonal regeneration, likely through a different post-translational pathway. These observations may suggest a novel therapeutic target for promoting regenerative responses following peripheral or central nervous system injuries.

Glycolysis is essential for the classical activation of macrophages (M1), but how glycolytic pathway metabolites engage in this process remains to be elucidated. Glycolysis leads to production of pyruvate, which can be transported into the mitochondria by the mitochondrial pyruvate carrier (MPC) followed by utilization in the tricarboxylic acid cycle. Based on studies that used the MPC inhibitor UK5099, the mitochondrial route has been considered to be of significance for M1 activation. Using genetic approaches, here we show that the MPC is dispensable for metabolic reprogramming and activation of M1 macrophages. In addition, MPC depletion in myeloid cells has no impact on inflammatory responses and macrophage polarization toward the M1 phenotype in a mouse model of endotoxemia. While UK5099 reaches maximal MPC inhibitory capacity at approximately 2-5 μM, higher concentrations are required to inhibit inflammatory cytokine production in M1 and this is independent of MPC expression. Taken together, MPC-mediated metabolism is dispensable for the classical activation of macrophages and UK5099 inhibits inflammatory responses in M1 macrophages due to effects other than MPC inhibition.

Hepatitis B virus (HBV) infection has been proven strongly associated with the initiation and progression of hepatocellular carcinoma (HCC). However, a substantial amount of virally-induced mechanisms that cause malignant transformation in the liver remains largely unexplored, especially for HBV-induced metabolic reprogramming. In the present study, we identified and confirmed the HBV integration breakpoints clustering at the C-terminal X gene is a tumor-specific event, and the C-terminal HBx is expressed more frequently in the tumors than normal liver tissues. Then, the oncogenic effect of the truncated HBx was validated in vitro and in vivo. Transcriptome sequencing revealed that TXNIP, as a downstream target of truncated HBx, negatively regulates glucose metabolism. Screening of public database and our clinical cohort exhibited that TXNIP is significantly down-regulated in HCC patients with truncated HBx expression, compared to those with full-length HBx expression and HBV-negative patients. Lower expression of TXNIP is negatively correlated with patient survival. We also reported evidence that truncated HBx down-regulates TXNIP expression by transactivation via the transcriptional repressor NFACT2. Additionally, the re-introduction of TXNIP inhibited the metabolic reprogramming from mitochondrial respiration to aerobic glycolysis induced by truncated HBx and further resulted in HCC growth arrest in vitro and in vivo. In summary, our finding proposes a promising diagnostic and therapeutic strategy for HBV-induced HCC. Citation Format: Yu Zhang. Glucose metabolic reprogramming in HBV-related hepatocellular carcinoma through C-terminal truncated HBx protein suppression of TXNIP [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5991.

Reprogramming hormone-sensitive prostate cancer to a lethal neuroendocrine cancer lineage by mitochondrial pyruvate carrier (MPC)

BackgroundMitochondrial dynamics plays an important role in tumour progression. However, how these dynamics integrate tumour metabolism in hepatocellular carcinoma (HCC) metastasis is still unclear.MethodsThe mitochondrial fusion protein mitofusin-1 (MFN1) expression and its prognostic value are detected in HCC. The effects and underlying mechanisms of MFN1 on HCC metastasis and metabolic reprogramming are analysed both in vitro and in vivo.ResultsMitochondrial dynamics, represented by constant fission and fusion, are found to be associated with HCC metastasis. High metastatic HCC displays excessive mitochondrial fission. Among genes involved in mitochondrial dynamics, MFN1 is identified as a leading downregulated candidate that is closely associated with HCC metastasis and poor prognosis. While promoting mitochondrial fusion, MFN1 inhibits cell proliferation, invasion and migration capacity both in vitro and in vivo. Mechanistically, disruption of mitochondrial dynamics by depletion of MFN1 triggers the epithelial-to-mesenchymal transition (EMT) of HCC. Moreover, MFN1 modulates HCC metastasis by metabolic shift from aerobic glycolysis to oxidative phosphorylation. Treatment with glycolytic inhibitor 2-Deoxy-d-glucose (2-DG) significantly suppresses the effects induced by depletion of MFN1.ConclusionsOur results reveal a critical involvement of mitochondrial dynamics in HCC metastasis via modulating glucose metabolic reprogramming. MFN1 may serve as a novel potential therapeutic target for HCC.