PDHA1 gene knockout in prostate cancer cells results in metabolic reprogramming towards greater glutamine dependence

Establishment of a prognostic risk model for prostate cancer based on Gleason grading and cuprotosis related genes

INTRODUCTION

Prostate cancer (PCa) is common in aging males, diagnosed via the Gleason grading system. The study explores the unexamined prognostic value of cuprotosis, a distinct cell death type, alongside Gleason grades in PCa.

METHODS

We explored Cuprotosis-related genes (CRGs) in prostate cancer (PCa), using NMF on TCGA-PRAD data for patient classification and WGCNA to link genes with Gleason scores and prognosis. A risk model was crafted via LASSO Cox regression. STX3 knockdown in PC-3 cells, analyzed for effects on cell behaviors and tumor growth in mice, highlighted its potential therapeutic impact.

RESULTS

We identified five genes crucial for a prognostic risk model, with higher risk scores indicating worse prognosis. Survival analysis and ROC curves confirmed the model's predictive accuracy in TCGA-PRAD and GSE70769 datasets. STX3 was a key adverse prognostic factor, with its knockdown significantly reducing mRNA and protein levels, impairing PC-3 cell functions. In vivo, STX3 knockdown in PC-3 cells led to significantly smaller tumors in nude mice, underscoring its potential therapeutic value.

CONCLUSION

Our prognostic model, using five genes linked to Gleason scores, effectively predicts prostate cancer outcomes, offering a novel treatment strategy angle.

Metabolomic profiles of intact tissues reflect clinically relevant prostate cancer subtypes

BACKGROUND

Prostate cancer (PC) is a heterogenous multifocal disease ranging from indolent to lethal states. For improved treatment-stratification, reliable approaches are needed to faithfully differentiate between high- and low-risk tumors and to predict therapy response at diagnosis.

METHODS

A metabolomic approach based on high resolution magic angle spinning nuclear magnetic resonance (HR MAS NMR) analysis was applied on intact biopsies samples (n = 111) obtained from patients (n = 31) treated by prostatectomy, and combined with advanced multi- and univariate statistical analysis methods to identify metabolomic profiles reflecting tumor differentiation (Gleason scores and the International Society of Urological Pathology (ISUP) grade) and subtypes based on tumor immunoreactivity for Ki67 (cell proliferation) and prostate specific antigen (PSA, marker for androgen receptor activity).

RESULTS

Validated metabolic profiles were obtained that clearly distinguished cancer tissues from benign prostate tissues. Subsequently, metabolic signatures were identified that further divided cancer tissues into two clinically relevant groups, namely ISUP Grade 2 (n = 29) and ISUP Grade 3 (n = 17) tumors. Furthermore, metabolic profiles associated with different tumor subtypes were identified. Tumors with low Ki67 and high PSA (subtype A, n = 21) displayed metabolite patterns significantly different from tumors with high Ki67 and low PSA (subtype B, n = 28). In total, seven metabolites; choline, peak for combined phosphocholine/glycerophosphocholine metabolites (PC + GPC), glycine, creatine, combined signal of glutamate/glutamine (Glx), taurine and lactate, showed significant alterations between PC subtypes A and B.

CONCLUSIONS

The metabolic profiles of intact biopsies obtained by our non-invasive HR MAS NMR approach together with advanced chemometric tools reliably identified PC and specifically differentiated highly aggressive tumors from less aggressive ones. Thus, this approach has proven the potential of exploiting cancer-specific metabolites in clinical settings for obtaining personalized treatment strategies in PC.

AP2α negatively regulates PDHA1 in cervical cancer cells to promote aggressive features and aerobic glycolysis in vitro and in vivo

OBJECTIVE

As a gate-keeper enzyme link, pyruvate dehydrogenase E1 subunit alpha (PDHA1) functions as a key regulator during glycolysis and the mitochondrial citric acid cycle, which has been reported in several tumors. Nevertheless, the effects of PDHA1 on biological behaviors and metabolism remain unclear in cervical cancer (CC) cells. The study aims to explore the PDHA1 effects on glucose metabolism in CC cells and its possible mechanism.

METHODS

We first determined the expression levels of PDHA1 and activating protein 2 alpha (AP2α) as a PDHA1 potential transcription factor. The effects of PDHA1 in vivo were evaluated through a subcutaneous xenograft mouse model. Cell Counting Kit-8 assay, 5-ethynyl-2'-deoxyuridine (EdU) labeling assay, Transwell invasion assay, wound healing assay, Terminal deoxynucleotidyl transferase dUTP nick end labeling assay and flow cytometry were performed in CC cells. Oxygen consumption rate (OCR) levels were determined to reflect aerobic glycolysis level in gastric cancer cells. Reactive oxygen species (ROS) level was measured with 2', 7'-dichlorofluorescein diacetate kit. The relationship between PDHA1 and AP2α was examined by conducting chromatin immunoprecipitation assay and electrophoretic mobility shift assay.

RESULTS

In CC tissues and cell lines, PDHA1 was downregulated, while AP2α was upregulated. Overexpression of PDHA1 remarkedly inhibited the proliferation, invasion and migration of CC cells, and tumor growth in vivo, as well as promoted OCR, apoptosis and ROS production. Moreover, AP2α directly bound to PDHA1 within suppressor of cytokine signaling 3 promoter region to negatively regulate PDHA1 expression level. What is more, PDHA1 knockdown could effectively reversed the AP2α silencing-mediated suppressive effects on cell proliferation, invasion, migration, and the promotive effects of AP2α knockdown on OCR, apoptosis and ROS production.

CONCLUSIONS

Our findings demonstrate that AP2α negatively regulated PDHA1 via binding to PDHA1 gene promoter to promote malignant CC cell behaviors, which may provide a potential approach for CC therapeutics.

Prognostic and immune correlation evaluation of a novel cuproptosis-related genes signature in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the world's malignant tumors with high morbidity and mortality. Cuproptosis is a novel form of cell death. However, the prognostic evaluation and immune relevance of cuproptosis-related genes (CRGs) in HCC are largely unknown. In our study, we constructed a prognostic model of CRGs in HCC and performed immune infiltration, functional analysis, immune checkpoint and drug sensitivity analysis. Systematically elaborated the prognostic and immune correlation of CRGs in HCC. The results showed that 15 CRGs were up-regulated or down-regulated in HCC, and the mutation frequency of CRGs reached 10.33% in HCC, with CDKN2A having the highest mutation frequency. These 19 CRGs were mainly involved in the mitochondrion, immune response and metabolic pathways. Five selected genes (CDKN2A, DLAT, DLST, GLS, PDHA1) were involved in constructing a prognostic CRGs model that enables the overall survival in HCC patients to be predicted with moderate to high accuracy. Prognostic CRGs, especially CDKN2A, the independent factor of HCC prognosis, may be closely associated with immune-cell infiltration, tumor mutation burden (TMB), microsatellite instability(MSI), and immune checkpoints. CD274, CTLA4, LAG3, PDCD1, PDCD1LG2 and SIGLEC15 may be identified as potential therapeutic targets and CD274 correlated highly with prognostic genes. Quantitative Real-Time PCR (qRT-PCR) and immunohistochemical were performed to validate the mRNA and protein expression levels of CDKN2A in adjacent normal tissues and HCC tissues, and the results were consistent with gene difference analysis. In conclusion, CRGs, especially CDKN2A, may serve as potential prognostic predictors in HCC patients and provide novel insights into cancer therapy.

Insights into prognosis and immune infiltration of cuproptosis-related genes in breast cancer

Introduction

Breast cancer (BC) has been ranking first in incidence and the leading cause of death among female cancers worldwide based on the latest report. Regulated cell death (RCD) plays a significant role in tumor initiation and provides an important target of cancer treatment. Cuproptosis, a novel form of RCD, is ignited by mitochondrial stress, particularly the lipoylated mitochondrial enzymes aggregation. However, the role of cuproptosis-related genes (CRGs) in tumor generation and progression remains unclear.

Methods

In this study, the mRNA expression data of CRGs in BC and normal breast tissue were extracted from TCGA database, and protein expression patterns of these CRGs were analyzed using UALCAN. The prognostic values of CRGs in BC were explored by using KaplanMeier plotter and Cox regression analysis. Genetic mutations profiles were evaluated using the cBioPortal database. Meanwhile, we utilized CIBERSORT and TIMER 2.0 database to perform the correlation analysis between CRGs and immune cell infiltration.

Results

Our results indicated that CRGs expression is significantly different in BC and normal breast tissues. Then we found that upregulated PDHA1 expression was associated with worse endpoint of BC. Moreover, we also performed immune infiltration analysis of CRGs, and demonstrated that PDHA1 expression was closely related to the infiltration levels of CD4+ memory T cell, macrophage M0 and M1 cell and mast cell in BC.

Conclusions

Our results demonstrated the prognostic and immunogenetic values of PDHA1 in BC. Therefore, PDHA1 can be an independent prognostic biomarker and potential target for immunotherapy of BC.

Comprehensive analysis of the relationship between cuproptosis-related genes and esophageal cancer prognosis

BACKGROUND

Esophageal cancer is one of the most common malignant tumors of the digestive system, with a 5-year survival rate of 15% to 50%. Cuproptosis, a unique kind of cell death driven by protein lipoylation, is strongly connected to mitochondrial metabolism. The clinical implications of cuproptosis-related genes in esophageal cancer, however, are mainly unknown.

AIM

To identify cuprotosis-related genes that are differentially expressed in esophageal cancer and investigate their prognostic significance.

METHODS

With |log fold change| > 1 and false discovery rate < 0.05 as criteria, the Wilcox test was used to evaluate the differentially expressed genes between 151 tumor tissues and 151 normal esophageal tissues. Cuproptosis-related genes were selected to be linked with prognosis using univariate Cox regression analysis. Genes were separated into high- and low- expression groups based on their cutoff value of gene expression, and the correlation between the two groups and overall survival or progression-free survival was investigated using the log-rank test. The C-index, calibration curve, and receiver operator characteristic (ROC) curve were used to assess a nomogram containing clinicopathological characteristics and cuproptosis-related genes.

RESULTS

Pyruvate dehydrogenase A1 (PDHA1) was found to be highly correlated with prognosis in univariate Cox regression analysis (hazard ratio = 22.96, 95% confidence interval = 3.09-170.73; P = 0.002). According to Kaplan-Meier survival curves, low expression of PDHA1 was associated with a better prognosis (log-rank P = 0.0007). There was no significant correlation between PDHA1 expression and 22 different types of immune cells. Tumor necrosis factor superfamily member 15 (TNFSF15) (P = 3.2 × 10^-6; r = 0.37), TNFRSF14 (P = 8.1 × 10^-8; r = 0.42), H long terminal repeat-associating 2 (P = 6.0 × 10^-8; r = 0.42) and galectin 9 (P = 3.1 × 10^-6; r = 0.37) were all found to be considerably greater in the high PDHA1 expression group, according to an analysis of genes related to 47 immunological checkpoints. The low PDHA1 expression group had significantly lower levels of cluster of differentiation 44 (CD44) (P = 0.00028; R = -0.29), TNFRSF18 (P = 1.2 × 10^-5; R = -0.35), programmed cell death 1 ligand 2 (P = 0.0032; R = -0.24), CD86 (P = 0.018; R = -0.19), and CD40 (P = 0.0047; R = -0.23), and the differences were statistically significant. We constructed a prognostic nomogram incorporating pathological type, tumor-node-metastasis stage, and PDHA1 expression, and the C-index, calibration curve, and ROC curve revealed that the nomogram’s predictive performance was good.

CONCLUSION

Cuproptosis-related genes can be used as a prognostic predictor for esophageal cancer patients, providing novel insights into cancer treatment.

Tumor glycolysis, an essential sweet tooth of tumor cells

Cancer cells undergo metabolic alterations to meet the immense demand for energy, building blocks, and redox potential. Tumors show glucose-avid and lactate-secreting behavior even in the presence of oxygen, a process known as aerobic glycolysis. Glycolysis is the backbone of cancer cell metabolism, and cancer cells have evolved various mechanisms to enhance it. Glucose metabolism is intertwined with other metabolic pathways, making cancer metabolism diverse and heterogeneous, where glycolysis plays a central role. Oncogenic signaling accelerates the metabolic activities of glycolytic enzymes, mainly by enhancing their expression or by post-translational modifications. Aerobic glycolysis ferments glucose into lactate which supports tumor growth and metastasis by various mechanisms. Herein, we focused on tumor glycolysis, especially its interactions with the pentose phosphate pathway, glutamine metabolism, one-carbon metabolism, and mitochondrial oxidation. Further, we describe the role and regulation of key glycolytic enzymes in cancer. We summarize the role of lactate, an end product of glycolysis, in tumor growth, and the metabolic adaptations during metastasis. Lastly, we briefly discuss limitations and future directions to improve our understanding of glucose metabolism in cancer.

Druggable Metabolic Vulnerabilities Are Exposed and Masked during Progression to Castration Resistant Prostate Cancer

There is an urgent need for exploring new actionable targets other than androgen receptor to improve outcome from lethal castration-resistant prostate cancer. Tumor metabolism has reemerged as a hallmark of cancer that drives and supports oncogenesis. In this regard, it is important to understand the relationship between distinctive metabolic features, androgen receptor signaling, genetic drivers in prostate cancer, and the tumor microenvironment (symbiotic and competitive metabolic interactions) to identify metabolic vulnerabilities. We explore the links between metabolism and gene regulation, and thus the unique metabolic signatures that define the malignant phenotypes at given stages of prostate tumor progression. We also provide an overview of current metabolism-based pharmacological strategies to be developed or repurposed for metabolism-based therapeutics for castration-resistant prostate cancer.

ISGylation of EMD promotes its interaction with PDHA to inhibit aerobic oxidation in lung adenocarcinoma

Abnormal nuclear structure caused by dysregulation of skeletal proteins is a common phenomenon in tumour cells. However, how skeletal proteins promote tumorigenesis remains uncovered. Here, we revealed the mechanism by which skeletal protein Emerin (EMD) promoted glucose metabolism to induce lung adenocarcinoma (LUAD). Firstly, we identified that EMD was highly expressed and promoted the malignant phenotypes in LUAD. The high expression of EMD might be due to its low level of ubiquitination. Additionally, the ISGylation at lysine 37 of EMD inhibited lysine 36 ubiquitination and upregulated EMD stability. We further explored that EMD could inhibit aerobic oxidation and stimulate glycolysis. Mechanistically, via its β‐catenin interaction domain, EMD bound with PDHA, stimulated serine 293 and 300 phosphorylation and inhibited PDHA expression, facilitated glycolysis of glucose that should enter the aerobic oxidation pathway, and EMD ISGylation was essential for EMD‐PDHA interaction. In clinical LUAD specimens, EMD was negatively associated with PDHA, while positively associated with EMD ISGylation, tumour stage and diameter. In LUAD with higher glucose level, EMD expression and ISGylation were higher. Collectively, EMD was a stimulator for LUAD by inhibiting aerobic oxidation via interacting with PDHA. Restricting cancer‐promoting role of EMD might be helpful for LUAD treatment.

Dual contribution of the mTOR pathway and of the metabolism of amino acids in prostate cancer

BACKGROUND

Prostate cancer is the leading cause of cancer in men, and its incidence increases with age. Among other risk factors, pre-existing metabolic diseases have been recently linked with prostate cancer, and our current knowledge recognizes prostate cancer as a condition with important metabolic anomalies as well. In malignancies, metabolic disorders are commonly associated with aberrations in mTOR, which is the master regulator of protein synthesis and energetic homeostasis. Although there are reports demonstrating the high dependency of prostate cancer cells for lipid derivatives and even for carbohydrates, the understanding regarding amino acids, and the relationship with the mTOR pathway ultimately resulting in metabolic aberrations, is still scarce.

CONCLUSIONS AND PERSPECTIVES

In this review, we briefly provide evidence supporting prostate cancer as a metabolic disease, and discuss what is known about mTOR signaling and prostate cancer. Next, we emphasized on the amino acids glutamine, leucine, serine, glycine, sarcosine, proline and arginine, commonly related to prostate cancer, to explore the alterations in their regulatory pathways and to link them with the associated metabolic reprogramming events seen in prostate cancer. Finally, we display potential therapeutic strategies for targeting mTOR and the referred amino acids, as experimental approaches to selectively attack prostate cancer cells.

A novel defined cuproptosis-related gene signature for predicting the prognosis of lung adenocarcinoma

Lung adenocarcinoma (LUAD) has become the most prevalent histologic subset of primary lung cancer, and effective innovative prognostic models are needed to enhance the feasibility of targeted therapies for the disease. Programmed cell death (PCD) performs an integral function in the origin and treatment of cancer. Some PCD-related effective signatures for predicting prognosis in LUAD patients could provide potential therapeutic options in LUAD. A copper-dependent cell death referred to as cuproptosis is distinct from known PCD. However, whether cuproptosis is associated with LUAD patients' prognoses and the potential roles of cuproptosis-related genes involved is still unknown. For the prediction of LUAD prognosis, we developed a unique cuproptosis-associated gene signature. In The Cancer Genome Atlas (TCGA) cohort, the score derived from the risk signature on the basis of six cuproptosis-related genes was found to independently serve as a risk factor for anticipating lung cancer-related death. The differentially expressed genes between the high- and low-risk groups were linked to the cilium-related function. LUAD patients’ prognoses may now be predicted by a unique gene signature identified in this work. This discovery also provides a substantial foundation for future research into the links between cuproptosis-associated genes and cilium-related function in LUAD patients.

Comprehensive analyses of PDHA1 that serves as a predictive biomarker for immunotherapy response in cancer

Recent studies have proposed that pyruvate dehydrogenase E1 component subunit alpha (PDHA1), a cuproptosis-key gene, is crucial to the glucose metabolism reprogram of tumor cells. However, the functional roles and regulated mechanisms of PDHA1 in multiple cancers are largely unknown. The Cancer Genome Atlas (TCGA), GEPIA2, and cBioPortal databases were utilized to elucidate the function of PDHA1 in 33 tumor types. We found that PDHA1 was aberrantly expressed in most cancer types. Lung adenocarcinoma (LUAD) patients with high PDHA1 levels were significantly correlated with poor prognosis of overall survival (OS) and first progression (FP). Kidney renal clear cell carcinoma (KIRC) patients with low PDHA1 levels displayed poor OS and disease-free survival (DFS). However, for stomach adenocarcinoma (STAD), the downregulated PDHA1 expression predicted a good prognosis in patients. Moreover, we evaluated the mutation diversity of PDHA1 in cancers and their association with prognosis. We also analyzed the protein phosphorylation and DNA methylation of PDHA1 in various tumors. The PDHA1 expression was negatively correlated with tumor-infiltrating immune cells, such as myeloid dendritic cells (DCs), B cells, and T cells in pan-cancers. Mechanically, we used single-cell sequencing to discover that the PDHA1 expression had a close link with several cancer-associated signaling pathways, such as DNA damage, cell invasion, and angiogenesis. At last, we conducted a co-expressed enrichment analysis and showed that aberrantly expressed PDHA1 participated in the regulation of mitochondrial signaling pathways, including oxidative phosphorylation, cellular respiration, and electron transfer activity. In summary, PDHA1 could be a prognostic and immune-associated biomarker in multiple cancers.

Identification and Validation of Cuproptosis-Related Prognostic Signature and Associated Regulatory Axis in Uterine Corpus Endometrial Carcinoma

Background: Uterine corpus endometrial carcinoma (UCEC) is a common gynecological malignancy globally with high recurrence and mortality rates. Cuproptosis is a new type of programmed cell death involved in tumor cell proliferation and growth, angiogenesis, and metastasis.

Methods: The difference in cuproptosis-related genes (CRGs) between UCEC tissues and normal tissues deposited in The Cancer Genome Atlas database was calculated using the “limma” R package. LASSO Cox regression analysis was conducted to construct a prognostic cuproptosis–related signature. Kaplan–Meier analysis was conducted to compare the survival of UCEC patients. A ceRNA network was constructed to identify the lncRNA–miRNA–mRNA regulatory axis. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was performed to verify CRG expression in UCEC.

Results: The expression of FDX1, LIAS, DLAT, and CDKN2A were upregulated, whereas the expression of LIPT1, DLD, PDHB, MTF1, and GLS were downregulated in UCEC versus normal tissues. The genetic mutation landscape of CRGs in UCEC was also summarized. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses revealed that these CRGs were enriched in the tricarboxylic acid (TCA) cycle, glycolysis, and HIF-1 signaling pathway. LASSO Cox regression analysis was performed and identified a cuproptosis-related prognostic signature including these three prognostic biomarkers (CDKN2A, GLS, and LIPT1). UCEC patients with high risk scores had a poor prognosis with an area under the curve of 0.782 and 0.764 on 3- and 5-year receiver operating characteristic curves. Further analysis demonstrated a significant correlation between CDKN2A and pTNM stage, tumor grade, immune cell infiltration, drug sensitivity, tumor mutational burden (TMB) score, and microsatellite instable (MSI) score. The data validation of qRT-PCR further demonstrated the upregulation of CDKN2A and the downregulation of LIPT1 and GLS in UCEC versus normal tissues. The ceRNA network also identified lncRNA XIST/miR-125a-5p/CDKN2A regulatory axis for UCEC.

Conclusion: The current study identified a cuproptosis-related prognostic signature including these three prognostic biomarkers (CDKN2A, GLS, and LIPT1) for UCEC. The ceRNA network also identified that lncRNA XIST/miR-125a-5p/CDKN2A regulatory axis may be involved in the progression of UCEC. Further in vivo and in vitro studies should be conducted to verify these results.

Heterogeneous Expression and Subcellular Localization of Pyruvate Dehydrogenase Complex in Prostate Cancer

Background

Pyruvate dehydrogenase (PDH) complex converts pyruvate into acetyl-CoA by pyruvate decarboxylation, which drives energy metabolism during cell growth, including prostate cancer (PCa) cell growth. The major catalytic subunit of PDH, PDHA1, is regulated by phosphorylation/dephosphorylation by pyruvate dehydrogenase kinases (PDKs) and pyruvate dehydrogenase phosphatases (PDPs). There are four kinases, PDK1, PDK2, PDK3 and PDK4, which can phosphorylate and inactivate PDH; and two phosphatases, PDP1 and PDP2, that dephosphorylate and activate PDH.

Methods

We have analyzed by immunohistochemistry the expression and clinicopathological correlations of PDHA1, PDP1, PDP2, PDK1, PDK2, PDK3, and PDK4, as well as of androgen receptor (AR), in a retrospective PCa cohort of patients. A total of 120 PCa samples of representative tumor areas from all patients were included in tissue microarray (TMA) blocks for analysis. In addition, we studied the subcellular localization of PDK2 and PDK3, and the effects of the PDK inhibitor dichloroacetate (DCA) in the growth, proliferation, and mitochondrial respiration of PCa cells.

Results

We found heterogeneous expression of the PDH complex components in PCa tumors. PDHA1, PDP1, PDK1, PDK2, and PDK4 expression correlated positively with AR expression. A significant correlation of PDK2 immunostaining with biochemical recurrence and disease-free survival was revealed. In PCa tissue specimens, PDK2 displayed cytoplasmic and nuclear immunostaining, whereas PDK1, PDK3 and PDK4 showed mostly cytoplasmic staining. In cells, ectopically expressed PDK2 and PDK3 were mainly localized in mitochondria compartments. An increase in maximal mitochondrial respiration was observed in PCa cells upon PDK inhibition by DCA, in parallel with less proliferative capacity.

Conclusion

Our findings support the notion that expression of specific PDH complex components is related with AR signaling in PCa tumors. Furthermore, PDK2 expression associated with poor PCa prognosis. This highlights a potential for PDH complex components as targets for intervention in PCa.

Pyruvate Dehydrogenase Contributes to Drug Resistance of Lung Cancer Cells Through Epithelial Mesenchymal Transition

Recently, there has been a growing interest on the role of mitochondria in metastatic cascade. Several reports have shown the preferential utilization of glycolytic pathway instead of mitochondrial respiration for energy production and the pyruvate dehydrogenase (PDH) has been considered to be a contributor to this switch in some cancers. Since epithelial mesenchymal transition (EMT) is proposed to be one of the significant mediators of metastasis, the molecular connections between cancer cell metabolism and EMT may reveal underlying mechanisms and improve our understanding on metastasis. In order to explore a potential role for PDH inhibition on EMT and associated drug resistance, we took both pharmacological and genetic approaches, and selectively inhibited or knocked down PDHA1 by using Cpi613 and shPDHA1, respectively. We found that both approaches triggered morphological changes and characteristics of EMT (increase in mesenchymal markers). This change was accompanied by enhanced wound healing and an increase in migration. Interestingly, cells were more resistant to many of the clinically used chemotherapeutics following PDH inhibition or PDHA1 knockdown. Furthermore, the TGFβRI (known as a major inducer of the EMT) inhibitor (SB-431542) together with the PDHi, was effective in reversing EMT. In conclusion, interfering with PDH induced EMT, and more importantly resulted in chemoresistance. Therefore, our study demonstrates the need for careful consideration of PDH-targeting approaches in cancer treatment.

Blockade of glutamine-dependent cell survival augments antitumor efficacy of CPI-613 in head and neck cancer

BACKGROUND

Alterations in metabolism are one of the emerging hallmarks of cancer cells and targeting dysregulated cancer metabolism provides a new approach to developing more selective therapeutics. However, insufficient blockade critical metabolic dependencies of cancer allows the development of metabolic bypasses, thus limiting therapeutic benefits.

METHODS

A series of head and neck squamous cell carcinoma (HNSCC) cell lines and animal models were used to determine the efficacy of CPI-613 and CB-839 when given alone or in combination. Glutaminase 1 (GLS1) depletion was achieved by lentiviral shRNAs. Cell viability and apoptosis were determined in HNSCC cells cultured in 2D culture dish and SeedEZ™ 3D scaffold. Molecular alterations were examined by Western blotting and immunohistochemistry. Metabolic changes were assessed by glucose uptake, lactate production, glutathione levels, and oxygen consumption rate.

RESULTS

We show here that HNSCC cells display strong addiction to glutamine. CPI-613, a novel lipoate analog, redirects cellular activity towards tumor-promoting glutaminolysis, leading to low anticancer efficacy in HNSCC cells. Mechanistically, CPI-613 inhibits the tricarboxylic acid cycle by blocking the enzyme activities of pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase, which upregulates GLS1 and eventually promotes the compensatory role of glutaminolysis in cancer cell survival. Most importantly, the addition of a GLS1 inhibitor CB-839 to CPI-613 treatment abrogates the metabolic dependency of HNSCC cells on glutamine, achieving a synergistic anticancer effect in glutamine-addicted HNSCC.

CONCLUSIONS

These findings uncover the critical role of GLS1-mediated glutaminolysis in CPI-613 treatment and suggest that the CB-839 and CPI-613 combination may potentiate synergistic anticancer activity for HNSCC therapeutic gain.

The Interplay Between Prostate Cancer Genomics, Metabolism, and the Epigenome: Perspectives and Future Prospects

Prostate cancer is a high-incidence cancer, often detected late in life. The prostate gland is an accessory gland that secretes citrate; an impaired citrate secretion reflects imbalances in the activity of enzymes in the TCA Cycle in mitochondria. Profiling studies on prostate tumours have identified significant metabolite, proteomic, and transcriptional modulations with an increased mitochondrial metabolic activity associated with localised prostate cancer. Here, we focus on the androgen receptor, c-Myc, phosphatase and tensin Homolog deleted on chromosome 10 (PTEN), and p53 as amongst the best-characterised genomic drivers of prostate cancer implicated in metabolic dysregulation and prostate cancer progression. We outline their impact on metabolic function before discussing how this may affect metabolite pools and in turn chromatin structure and the epigenome. We reflect on some recent literature indicating that mitochondrial mutations and OGlcNAcylation may also contribute to this crosstalk. Finally, we discuss the technological challenges of assessing crosstalk given the significant differences in the spatial sensitivity and throughput of genomic and metabolomic profiling approaches.

Exosomal miR-21-5p derived from cisplatin-resistant SKOV3 ovarian cancer cells promotes glycolysis and inhibits chemosensitivity of its progenitor SKOV3 cells by targeting PDHA1

Ovarian cancer (OC) is a common reason for gynecologic cancer death. Standard treatments of OC consist of surgery and chemotherapy. However, chemoresistance should be considered. Exosomal miR-21-5p has been shown to regulate the chemosensitivity of cancer cells through regulating pyruvate dehydrogenase E1 subunit alpha 1 (PDHA1). However, the role of miR-21-5p/PDHA1 in OC is unclear. The levels of miR-21-5p and PDHA1 in clinical samples and cells were investigated. Exosomes derived from SKOV3/cisplatin (SKOV3/DDP) cells (DDP-Exos) were isolated and used to treat SKOV3 cells to test DDP-Exos effects on SKOV3 cells. Extracellular acidification rate and oxygen consumption rate were tested with a Seahorse analyzer. Cell apoptosis was analyzed by a flow cytometer. PDHA1 was overexpressed and miR-21-5p was silenced in SKOV3 cells to study the underlying mechanism of miR-21-5p in OC. Quantitative real-time PCR and immunoblots were applied to measure gene expression at mRNA and protein levels. The levels of PDHA1 in DDP-resistant SKOV3 or tumor tissues were significantly decreased while the levels of miR-21-5p were remarkably upregulated. miR-21-5p in DDP-Exos was sharply increased compared to that of Exos. Data also indicated that DDP-Exos treatment suppressed the sensitivity of SKOV3 cells to DDP and promoted cell viability and glycolysis of SKOV3 cells through inhibiting PDHA1 by exosomal miR-21-5p. miR-21-5p derived from DDP-resistant SKOV3 OC cells promotes glycolysis and inhibits chemosensitivity of its progenitor SKOV3 cells by targeting PDHA1. Our data highlights the important role of miR-21-5p/PDHA1 axis in OC and sheds light on new therapeutic development.

Metabolic and Amino Acid Alterations of the Tumor Microenvironment

Metabolic changes driven by the hostile tumor microenvironment surrounding cancer cells and the effect of these changes on tumorigenesis and metastatic potential have been known for a long time. The usual point of interest is glucose and changes in its utilization by cancer cells, mainly in the form of the Warburg effect. However, amino acids, both intra- and extracellular, also represent an important aspect of tumour microenvironment, which can have a significant effect on cancer cell metabolism and overall development of the tumor. Namely, alterations in the metabolism of amino acids glutamine, sarcosine, aspartate, methionine and cysteine have been previously connected to the tumor progression and aggressivity of cancer. The aim of this review is to pinpoint current gaps in our knowledge of the role of amino acids as a part of the tumor microenvironment and to show the effect of various amino acids on cancer cell metabolism and metastatic potential. This review shows limitations and exceptions from the traditionally accepted model of Warburg effect in some cancer tissues, with the emphasis on prostate cancer, because the traditional definition of Warburg effect as a metabolic switch to aerobic glycolysis does not always apply. Prostatic tissue both in a healthy and transformed state significantly differs in many metabolic aspects, including the metabolisms of glucose and amino acids, from the metabolism of other tissues. Findings from different tissues are, therefore, not always interchangeable and have to be taken into account during experimentation modifying the environment of tumor tissue by amino acid supplementation or depletion, which could potentially serve as a new therapeutic approach.

Metabolic regulation of prostate cancer heterogeneity and plasticity

Metabolic reprogramming is one of the main hallmarks of cancer cells. It refers to the metabolic adaptations of tumor cells in response to nutrient deficiency, microenvironmental insults, and anti-cancer therapies. Metabolic transformation during tumor development plays a critical role in the continued tumor growth and progression and is driven by a complex interplay between the tumor mutational landscape, epigenetic modifications, and microenvironmental influences. Understanding the tumor metabolic vulnerabilities might open novel diagnostic and therapeutic approaches with the potential to improve the efficacy of current tumor treatments. Prostate cancer is a highly heterogeneous disease harboring different mutations and tumor cell phenotypes. While the increase of intra-tumor genetic and epigenetic heterogeneity is associated with tumor progression, less is known about metabolic regulation of prostate cancer cell heterogeneity and plasticity. This review summarizes the central metabolic adaptations in prostate tumors, state-of-the-art technologies for metabolic analysis, and the perspectives for metabolic targeting and diagnostic implications.

Methylcrotonoyl-CoA Carboxylase 2 Promotes Proliferation, Migration and Invasion and Inhibits Apoptosis of Prostate Cancer Cells Through Regulating GLUD1-P38 MAPK Signaling Pathway

Purpose

Prostate cancer (PCa) is the most common cancer in American men, and the mechanisms of development and progression are still not completely clear. Methylcrotonoyl-CoA carboxylase 2 (MCCC2) was previously identified overexpressed in PCa with lymph node metastasis, but its specific role and mechanisms need further investigation. This study aimed to investigate the role of MCCC2 in PCa cells and its underlying mechanisms.

Materials and Methods

Quantitative RT-PCR and Western blotting were used to detect MCCC2 mRNA and protein expression in normal prostate epithelium and cancerous cells. Upon manipulation of MCCC2 expression, cell proliferation was measured by CCK-8 assays and migration and invasion were determined by transwell assays. Changes of apoptosis, cell cycle and mitochondrial membrane potential were evaluated by flow cytometry. MCCC2-mediated signaling pathways were screened by bioinformatics and verified by RT-PCR and Western blotting. Finally, immunohistochemistry was performed to detect the expression of MCCC2 and glutamate dehydrogenase 1 (GLUD1) in PCa tissues to analyze their correlation.

Results

We demonstrated that MCCC2 promoted cell proliferation, migration and invasion but inhibited apoptosis in PCa cells. In addition, MCCC2 in 22Rv1 cells induced mitochondrial damage. In PCa tissues, MCCC2 overexpression associated with lymph node metastasis (P=0.001) and high Gleason scores (P<0.001). MCCC2 positively correlated with GLUD1 expression in PCa tissues (r=0.435, P<0.001). Ectopic overexpression of MCCC2 up-regulated GLUD1 and p38 MAPK expression, whereas inhibition of MCCC2 decreased GLUD1 and p38 MAPK expression.

Conclusion

MCCC2 exerts oncogenic function in PCa through regulating GLUD1-p38 MAPK signaling pathway, and it may be a potential treatment target.

Selective galactose culture condition reveals distinct metabolic signatures in pyruvate dehydrogenase and complex I deficient human skin fibroblasts

INTRODUCTION

A decline in mitochondrial function represents a key factor of a large number of inborn errors of metabolism, which lead to an extremely heterogeneous group of disorders.

OBJECTIVES

To gain insight into the biochemical consequences of mitochondrial dysfunction, we performed a metabolic profiling study in human skin fibroblasts using galactose stress medium, which forces cells to rely on mitochondrial metabolism.

METHODS

Fibroblasts from controls, complex I and pyruvate dehydrogenase (PDH) deficient patients were grown under glucose or galactose culture condition. We investigated extracellular flux using Seahorse XF24 cell analyzer and assessed metabolome fingerprints using NMR spectroscopy.

RESULTS

Incubation of fibroblasts in galactose leads to an increase in oxygen consumption and decrease in extracellular acidification rate, confirming adaptation to a more aerobic metabolism. NMR allowed rapid profiling of 41 intracellular metabolites and revealed clear separation of mitochondrial defects from controls under galactose using partial least squares discriminant analysis. We found changes in classical markers of mitochondrial metabolic dysfunction, as well as unexpected markers of amino acid and choline metabolism. PDH deficient cell lines showed distinct upregulation of glutaminolytic metabolism and accumulation of branched-chain amino acids, while complex I deficient cell lines were characterized by increased levels in choline metabolites under galactose.

CONCLUSION

Our results show the relevance of selective culture methods in discriminating normal from metabolic deficient cells. The study indicates that untargeted fingerprinting NMR profiles provide physiological insight on metabolic adaptations and can be used to distinguish cellular metabolic adaptations in PDH and complex I deficient fibroblasts.

Low expression of PDHA1 predicts poor prognosis in gastric cancer

PDH E1 component subunit alpha (PDHA1) has been reported to be biologically significant in several human tumors. The aim of this study was to investigate the expression of PDHA1 in gastric cancer (GC) and its relationship with clinicopathological characteristics and prognosis. Oncomine analysis of neoplastic vs. normal tissue showed that the mRNA levels of PDHA1 were significantly underexpressed in different types of GC across three analyses. Underexpression of PDHA1 was found in intestinal-type GC (P =  0.009), diffuse-type GC (P =  0.036), and mixed-type GC (P =  0.025). Immunohistochemical staining of the 174 GC tissue microarray showed that PDHA1 staining is much stronger in normal mucosa than in GC samples (P =  0.040). Furthermore, PDHA1 expression levels were found to be significantly lower in 69.05% (87/126) of poorly differentiated GCs as compared to the well or moderately differentiated ones (P =  0.037). Intriguingly, PDHA1 expression was significantly correlated with depth of invasion (P <  0.001), lymph node metastasis (P <  0.001), TNM stage (P <  0.001), and nerve invasion (P =  0.006). However, it was not correlated with gender, age, Lauren classification, and lymphovascular invasion (P > 0.05 for all). Kaplan-Meier analysis revealed that low tumor expression of PDHA1 was significantly correlated with a poorer overall survival in patients with GC (5-year overall survival rates for patients with low vs high PDHA1 expression = 49.8% vs 72.7%, hazard ratio of death from GC = 2.594, 95% CI = 1.527 to 4.408, P <  0.001). Multivariate analysis showed that PDHA1 (P =  0.025) was an independent predictor of overall survival. These findings are of potential clinical utility and merit further validation.

Analysis of cancer gene attributes using electrical sensor

Prediction of cancer gene attributes by their primary structure (long amino acid sequence) is instrumental in large-scale genomics projects, especially in the field of genomics. Various methods are proposed to predict gene characteristics from its primary structure, but accurate prediction of it is still very challenging task. Here we introduce an electrical network based sensor or detector to discriminate cancer and non-cancer cells based on two features i.e. amino acid sequence length, and hydrophilic/hydrophobic property. The electrical circuit consists of resistors, capacitors and inductors, is used for modeling individual amino acid and cascaded to form gene system. Corresponding electrical responses are judged using Bode and Nyquist analyzers and achieve 89.55% accuracy with 87.06% True Positive rate and 95.42% True Negative rate, demonstrate that proposed electrical sensor model is very promising for predicting the cancer gene attributes as well as non-cancer gene in the field of large-scale genomics study.

Overexpression of Pyruvate Dehydrogenase E1α Subunit Inhibits Warburg Effect and Induces Cell Apoptosis Through Mitochondria-Mediated Pathway in Hepatocellular Carcinoma

Most cancers rely disproportionately on glycolysis for energy even in the presence of an adequate oxygen supply, a condition known as “aerobic glycolysis,” or the “Warburg effect.” Pyruvate dehydrogenase E1α subunit (PDHA1) is one of the main factors for the metabolic switch from oxidative phosphorylation (OXPHOS) to aerobic glycolysis and has been suggested to be closely associated with tumorigenesis. Here we observed that the PDHA1 protein was reduced in hepatocellular carcinoma (HCC) specimens by immunohistochemistry and Western blot, which was significantly associated with poor overall survival. To further analyze the function of PDHA1 in cancer cells, PDHA1 was upregulated in the HCC cell lines SMMC-7721 and HepG2. The results demonstrated that overexpression of the PDHA1 gene inhibited aerobic glycolysis with lower lactate via increased PDH activity; meanwhile, mitochondrial OXPHOS was enhanced accompanied with higher ATP and lower glucose consumption. We also found that apoptosis was promoted and intrinsic pathway proteins were increased in PDHA1-overexpressing cells. Collectively, our data indicate that reduced PDHA1 protein expression is associated with the poor clinical outcome of HCC. Upregulated PDHA1 gene expression can inhibit the Warburg effect and enhance the mitochondria-mediated apoptosis pathway.

ACSS2-mediated acetyl-CoA synthesis from acetate is necessary for human cytomegalovirus infection

Recent studies have shown that human cytomegalovirus (HCMV) can induce a robust increase in lipid synthesis which is critical for the success of infection. In mammalian cells the central precursor for lipid biosynthesis, cytosolic acetyl CoA (Ac-CoA), is produced by ATP-citrate lyase (ACLY) from mitochondria-derived citrate or by acetyl-CoA synthetase short-chain family member 2 (ACSS2) from acetate. It has been reported that ACLY is the primary enzyme involved in making cytosolic Ac-CoA in cells with abundant nutrients. However, using CRISPR/Cas9 technology, we have shown that ACLY is not essential for HCMV growth and virally induced lipogenesis. Instead, we found that in HCMV-infected cells glucose carbon can be used for lipid synthesis by both ACLY and ACSS2 reactions. Further, the ACSS2 reaction can compensate for the loss of ACLY. However, in ACSS2-KO human fibroblasts both HCMV-induced lipogenesis from glucose and viral growth were sharply reduced. This reduction suggests that glucose-derived acetate is being used to synthesize cytosolic Ac-CoA by ACSS2. Previous studies have not established a mechanism for the production of acetate directly from glucose metabolism. Here we show that HCMV-infected cells produce more glucose-derived pyruvate, which can be converted to acetate through a nonenzymatic mechanism.