p53 regulates biosynthesis through direct inactivation of glucose-6-phosphate dehydrogenase

Reactive oxygen species and its role in pathogenesis and resistance to therapy in acute myeloid leukemia

Relapse following a short clinical response to therapy is the major challenge for the management of acute myeloid leukemia (AML) patients. Leukemic stem cells (LSC), as the source of relapse, have been investigated for their metabolic preferences and their alterations at the time of relapse. As LSC rely on oxidative phosphorylation (OXPHOS) for energy requirement, reactive oxygen species (ROS), as by-products of OXPHOS, have been investigated for their role in the effectiveness of the standard AML therapy. Increased levels of non-mitochondrial ROS, generated by nicotinamide adenine dinucleotide phosphate oxidase, in a subgroup of AML patients add to the complexity of studying ROS. Although there are various studies presenting the contribution of ROS to AML pathogenesis, resistance, and its inhibition or activation as a target, a model that can clearly explain its role in AML has not been conceptualized. This is due to the heterogeneity of AML, the dynamics of ROS production, which is influenced by factors such as the type of treatment, cell differentiation state, mitochondrial activity, and also the heterogeneous generation of non-mitochondrial ROS and limited available data on their interaction with the microenvironment. This review summarizes these challenges and the recent progress in this field.

HuaChanSu suppresses the growth of hepatocellular carcinoma cells by interfering with pentose phosphate pathway through down-regulation of G6PD enzyme activity and expression

HuaChanSu is active water extracts from the skin of Bufo bufo gargarizans Cantor. It has been already used to treat clinical cancers including HCC (Hepatocellular carcinoma, HCC), however, the molecular mechanisms under HuaChanSu's anti-cancer effects remain unclear. PPP (Pentose phosphate pathway, PPP), the major source of ribose and NADPH (Nicotinamide adenine dinucleotide phosphate, NADPH), is always over-activated and particularly critical for tumor cells growth. In this study, firstly, we illustrate that HuaChanSu restrains the growth of human hepatoma cells. More importantly, we demonstrate that the expression of G6PD (Glucose-6-phosphate dehydrogenase, G6PD), the first rate-limiting enzyme of the PPP, is restrained in human hepatoma cells after treatment with HuaChanSu. Additionally, our results show that G6PD enzyme activity and dimer formation are inhibited by HuaChanSu. Furthermore, we find that HuaChanSu could inhibit NADPH production and nucleotide level. In addition, we identify that expression of PLK1 (Polo-like kinase 1, PLK1) is also reduced in response to HuaChanSu, and knockdown of PLK1 restrains enzyme activity and dimer formation of G6PD, but has no effect on G6PD protein level. Subsequently, we demonstrate that inhibition of G6PD could restrain the proliferation of tumor cells and enhance the inhibitory effect of HuaChanSu on cell proliferation of human hepatoma cells. In conclusion, for the first time, our study reveals that HuaChanSu interferes with PPP via suppression of G6PD expression and enzyme activity to restrain growth of tumor cells, and these results provide a novel insight for the anti-hepatoma mechanisms of HuaChanSu and promote the innovation of the research model of TCM. Moreover, the development of drugs targeting abnormal tumor metabolism is currently a hot topic, our works provide theoretical support for further drug development from HuaChanSu, meanwhile, the revelation of the new molecular mechanism also provides a new perspective for the study of the pathogenesis of liver cancer.

Short abstract

HuaChanSu suppresses expression of G6PD, the first rate-limiting enzyme of the PPP, restrains G6PD enzyme activity and dimer formation via inhibition of PLK1, knockdown of G6PD could impair the growth of human hepatoma cells and increase the blocking effect of HuaChanSu on cell proliferation of cancer cells. In addition, HuaChanSu restrains NADPH production and nucleotide level, implying the suppression of PPP flux. Our study suggests that HuaChanSu interferes with PPP via G6PD inhibition to exert anti-hepatoma effects.

Using tumor habitat-derived radiomic analysis during pretreatment 18F-FDG PET for predicting KRAS/NRAS/BRAF mutations in colorectal cancer

BACKGROUND

To investigate the association between Kirsten rat sarcoma viral oncogene homolog (KRAS) / neuroblastoma rat sarcoma viral oncogene homolog (NRAS) /v-raf murine sarcoma viral oncogene homolog B (BRAF) mutations and the tumor habitat-derived radiomic features obtained during pretreatment 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in patients with colorectal cancer (CRC).

METHODS

We retrospectively enrolled 62 patients with CRC who had undergone 18F-FDG PET/computed tomography from January 2017 to July 2022 before the initiation of therapy. The patients were randomly split into training and validation cohorts with a ratio of 6:4. The whole tumor region radiomic features, habitat-derived radiomic features, and metabolic parameters were extracted from 18F-FDG PET images. After reducing the feature dimension and selecting meaningful features, we constructed a hierarchical model of KRAS/NRAS/BRAF mutations by using the support vector machine. The convergence of the model was evaluated by using learning curve, and its performance was assessed based on the area under the receiver operating characteristic curve (AUC), calibration curve, and decision curve analysis. The SHapley Additive exPlanation was used to interpret the contributions of various features to predictions of the model.

RESULTS

The model constructed by using habitat-derived radiomic features had adequate predictive power with respect to KRAS/NRAS/BRAF mutations, with an AUC of 0.759 (95% CI: 0.585-0.909) on the training cohort and that of 0.701 (95% CI: 0.468-0.916) on the validation cohort. The model exhibited good convergence, suitable calibration, and clinical application value. The results of the SHapley Additive explanation showed that the peritumoral habitat and a high_metabolism habitat had the greatest impact on predictions of the model. No meaningful whole tumor region radiomic features or metabolic parameters were retained during feature selection.

CONCLUSION

The habitat-derived radiomic features were found to be helpful in stratifying the status of KRAS/NRAS/BRAF in CRC patients. The approach proposed here has significant implications for adjuvant treatment decisions in patients with CRC, and needs to be further validated on a larger prospective cohort.

Hepatic Huwe1 loss protects mice from non-alcoholic fatty liver disease through lipid metabolic rewiring

Non-alcoholic fatty liver disease (NAFLD) is the most pervasive liver pathology worldwide. Here, we demonstrate that the ubiquitin E3 ligase Huwe1 is vital in NAFLD pathogenesis. Using mass spectrometry and RNA sequencing, we reveal that liver-specific deletion of Huwe1 (Huwe1LKO) in 1-year-old mice (approximately middle age in humans) elicits extensive lipid metabolic reprogramming that involves downregulation of de novo lipogenesis and fatty acid uptake, upregulation of fatty acid β-oxidation, and increased oxidative phosphorylation. ChEA transcription factor prediction analysis inferred these changes result from attenuated PPARɑ, LXR, and RXR activity in Huwe1LKO livers. Consequently, Huwe1LKO mice fed chow diet exhibited significantly reduced hepatic steatosis and superior glucose tolerance compared to wild-type mice. Huwe1LKO also conferred protection from high-fat diet-induced hepatic steatosis by 6-months of age, with increasingly robust differences observed as mice reached middle age. Together, we present evidence that Huwe1 plays a critical role in the development of age- and diet-induced NAFLD.

The Role of Tumor Metabolic Reprogramming in Tumor Immunity

The occurrence and development of tumors require the metabolic reprogramming of cancer cells, namely the alteration of flux in an autonomous manner via various metabolic pathways to meet increased bioenergetic and biosynthetic demands. Tumor cells consume large quantities of nutrients and produce related metabolites via their metabolism; this leads to the remodeling of the tumor microenvironment (TME) to better support tumor growth. During TME remodeling, the immune cell metabolism and antitumor immune activity are affected. This further leads to the escape of tumor cells from immune surveillance and therefore to abnormal proliferation. This review summarizes the regulatory functions associated with the abnormal biosynthesis and activity of metabolic signaling molecules during the process of tumor metabolic reprogramming. In addition, we provide a comprehensive description of the competition between immune cells and tumor cells for nutrients in the TME, as well as the metabolites required for tumor metabolism, the metabolic signaling pathways involved, and the functionality of the immune cells. Finally, we summarize current research targeted at the development of tumor immunotherapy. We aim to provide new concepts for future investigations of the mechanisms underlying the metabolic reprogramming of tumors and explore the association of these mechanisms with tumor immunity.

Cyclosporine A alleviates colitis by inhibiting the formation of neutrophil extracellular traps via the regulating pentose phosphate pathway

BACKGROUND

The aberrant formation of neutrophil extracellular traps (NETs) has been implicated in ulcerative colitis (UC), a chronic recurrent intestinal inflammation. Cyclosporine A (CsA) is now applied as rescue therapy for acute severe UC. In addition, it has been certained that CsA inhibits the formation of NETs in vitro and the mechanism of which was still vague. The study aimed to explore the mechanism CsA inhibits the NETs formation of colitis in vivo and in vitro.

METHODS

NETs enrichment in clinical samples was analyzed using databases from Gene Expression Omnibus and verified in our center. Dextran sulfate sodium (DSS)-induced acute colitis mice model was used to investigate the effect of CsA on NETs of colonic tissue expression. To clarify the mechanism, intracellular energy metabolites were examined by Liquid Chromatograph Mass Spectrometer, and reactive oxygen species (ROS) levels were examined by fluorescence intensity in neutrophils treated with CsA after LPS stimulation. The transcriptional level and activity of G6PD of neutrophils were also assessed using qRT-PCR and WST-8. RNA Sequencing was used to detect differentially expressed genes of neutrophils stimulated by LPS with or without CsA. The expression levels of related proteins were detected by western blot.

RESULTS

NETs enrichment was especially elevated in moderate-to-severe UC patients compared to HC. NETs expression in the colon from DSS colitis was decreased after CsA treatment. Compared with neutrophils stimulated by LPS, NETs formation and cellular ROS levels were decreased in LPS + CsA group. Cellular ribulose 5-phosphate and NADPH/NADP + related to the pentose phosphate pathway (PPP) were reduced in LPS + CsA group. In addition, CsA could decrease G6PD activity in neutrophils stimulated with LPS, and the results were further verified by inhibiting G6PD activity. At last, P53 protein was highly expressed in LPS + CsA group compared with the LPS group. Intracellular G6PD activity, ROS level and NETs formation, which were downregulated by CsA, could be reversed by a P53 inhibitor.

CONCLUSION

Our results indicated CsA could alleviate the severity of colitis by decreasing the formation of NETs in vivo. In vitro, CsA reduced ROS-dependent NETs release via downregulating PPP and cellular ROS levels by decreasing G6PD activity directly by activating the P53 protein.

Expanding Roles of the E2F-RB-p53 Pathway in Tumor Suppression

The transcription factor E2F links the RB pathway to the p53 pathway upon loss of function of pRB, thereby playing a pivotal role in the suppression of tumorigenesis. E2F fulfills a major role in cell proliferation by controlling a variety of growth-associated genes. The activity of E2F is controlled by the tumor suppressor pRB, which binds to E2F and actively suppresses target gene expression, thereby restraining cell proliferation. Signaling pathways originating from growth stimulative and growth suppressive signals converge on pRB (the RB pathway) to regulate E2F activity. In most cancers, the function of pRB is compromised by oncogenic mutations, and E2F activity is enhanced, thereby facilitating cell proliferation to promote tumorigenesis. Upon such events, E2F activates the Arf tumor suppressor gene, leading to activation of the tumor suppressor p53 to protect cells from tumorigenesis. ARF inactivates MDM2, which facilitates degradation of p53 through proteasome by ubiquitination (the p53 pathway). P53 suppresses tumorigenesis by inducing cellular senescence or apoptosis. Hence, in almost all cancers, the p53 pathway is also disabled. Here we will introduce the canonical functions of the RB-E2F-p53 pathway first and then the non-classical functions of each component, which may be relevant to cancer biology.

The Emerging Roles of the Metabolic Regulator G6PD in Human Cancers

Metabolic reprogramming, especially reprogrammed glucose metabolism, is a well-known cancer hallmark related to various characteristics of tumor cells, including proliferation, survival, metastasis, and drug resistance. Glucose-6-phosphate dehydrogenase (G6PD) is the first and rate-limiting enzyme of the pentose phosphate pathway (PPP), a branch of glycolysis, that converts glucose-6-phosphate (G6P) into 6-phosphogluconolactone (6PGL). Furthermore, PPP produces ribose-5-phosphate (R5P), which provides sugar-phosphate backbones for nucleotide synthesis as well as nicotinamide adenine dinucleotide phosphate (NADPH), an important cellular reductant. Several studies have shown enhanced G6PD expression and PPP flux in various tumor cells, as well as their correlation with tumor progression through cancer hallmark regulation, especially reprogramming cellular metabolism, sustaining proliferative signaling, resisting cell death, and activating invasion and metastasis. Inhibiting G6PD could suppress tumor cell proliferation, promote cell death, reverse chemoresistance, and inhibit metastasis, suggesting the potential of G6PD as a target for anti-tumor therapeutic strategies. Indeed, while challenges-including side effects-still remain, small-molecule G6PD inhibitors showing potential anti-tumor effect either when used alone or in combination with other anti-tumor drugs have been developed. This review provides an overview of the structural significance of G6PD, its role in and regulation of tumor development and progression, and the strategies explored in relation to G6PD-targeted therapy.

The role of LSM1 in breast cancer: Shaping metabolism and tumor-associated macrophage infiltration

LSM1 is part of the cytoplasmic protein complex Lsm1-7-Pat1 and is likely involved in pre-mRNA degradation by aiding U4/U6 snRNP formation. More research is needed to uncover LSM1's potential in breast cancer (BRCA) clinical pathology, the tumor immune microenvironment, and precision oncology. We discovered LSM1 as a diagnostic marker for advanced BRCA with poor survival, using a multi-omics approach. We studied LSM1 expression across BRCA regions and its link to immune cells through various methods, including spatial transcriptomics and single-cell RNA-sequencing. We also examined how silencing LSM1 affects mitochondrial function and energy metabolism in the tumor environment. These findings were confirmed using 54 BRCA patient biopsies and tissue microarrays. Immunofluorescence and bioinformatics assessed LSM1's connection to clinicopathological features and prognosis. This study uncovers gene patterns linked to breast cancer, with LSM1 linked to macrophage energy processes. Silencing LSM1 in breast cancer cells disrupts mitochondria and energy metabolism. Spatial analysis aligns with previous results, showing LSM1's connection to macrophages. Biopsies confirm LSM1 elevation in advanced breast cancer with increased macrophage presence. To summarize, LSM1 changes may drive BRCA progression, making it a potential diagnostic and prognostic marker. It also influences energy metabolism and the tumor's immune environment during metastasis, showing promise for precision medicine and drug screening in BRCA.

CircNOLC1 Promotes Colorectal Cancer Liver Metastasis by Interacting with AZGP1 and Sponging miR-212-5p to Regulate Reprogramming of the Oxidative Pentose Phosphate Pathway

Liver metastasis is a common cause of death in progressive colorectal cancer patients, but the molecular mechanisms remain unclear. Here, it is reported that a conserved and oxidative pentose phosphate pathway-associated circular RNA, circNOLC1, plays a crucial role in colorectal cancer liver metastasis. It is found that circNOLC1 silencing reduces the oxidative pentose phosphate pathway-related intermediate metabolites and elevates NADP+ /NADPH ratio and intracellular ROS levels, thereby attenuating colorectal cancer cell proliferation, migration, and liver metastasis. circNOLC1 interacting with AZGP1 to activate mTOR/SREBP1 signaling, or sponging miR-212-5p to upregulate c-Met expression, both of which can further induce G6PD to activate oxidative pentose phosphate pathway in colorectal cancer liver metastasis. Moreover, circNOLC1 is regulated by the transcription factor YY1 and specifically stabilized HuR induces its parental gene mRNA expression. The associations between circNOLC1 and these signaling molecules are validated in primary CRC and corresponding liver metastasis tissues. These findings reveal that circNOLC1 interacting with AZGP1 and circNOLC1/miR-212-5p/c-Met axis plays a key role in oxidative pentose phosphate pathway-mediated colorectal cancer liver metastasis, which may provide a novel target for precision medicine of colorectal cancer.

G6PD Maintains Redox Homeostasis and Biosynthesis in LKB1-Deficient KRAS-Driven Lung Cancer

Cancer cells depend on nicotinamide adenine dinucleotide phosphate (NADPH) to combat oxidative stress and support reductive biosynthesis. One major NAPDH production route is the oxidative pentose phosphate pathway (committed step: glucose-6-phosphate dehydrogenase, G6PD). Alternatives exist and can compensate in some tumors. Here, using genetically-engineered lung cancer model, we show that ablation of G6PD significantly suppresses KrasG12D/+;Lkb1-/- (KL) but not KrasG12D/+;p53-/- (KP) lung tumorigenesis. In vivo isotope tracing and metabolomics revealed that G6PD ablation significantly impaired NADPH generation, redox balance and de novo lipogenesis in KL but not KP lung tumors. Mechanistically, in KL tumors, G6PD ablation caused p53 activation that suppressed tumor growth. As tumor progressed, G6PD-deficient KL tumors increased an alternative NADPH source, serine-driven one carbon metabolism, rendering associated tumor-derived cell lines sensitive to serine/glycine depletion. Thus, oncogenic driver mutations determine lung cancer dependence on G6PD, whose targeting is a potential therapeutic strategy for tumors harboring KRAS and LKB1 co-mutations.

Acetylation-dependent coupling between G6PD activity and apoptotic signaling

Lysine acetylation has been discovered in thousands of non-histone human proteins, including most metabolic enzymes. Deciphering the functions of acetylation is key to understanding how metabolic cues mediate metabolic enzyme regulation and cellular signaling. Glucose-6-phosphate dehydrogenase (G6PD), the rate-limiting enzyme in the pentose phosphate pathway, is acetylated on multiple lysine residues. Using site-specifically acetylated G6PD, we show that acetylation can activate (AcK89) and inhibit (AcK403) G6PD. Acetylation-dependent inactivation is explained by structural studies showing distortion of the dimeric structure and active site of G6PD. We provide evidence for acetylation-dependent K95/97 ubiquitylation of G6PD and Y503 phosphorylation, as well as interaction with p53 and induction of early apoptotic events. Notably, we found that the acetylation of a single lysine residue coordinates diverse acetylation-dependent processes. Our data provide an example of the complex roles of acetylation as a posttranslational modification that orchestrates the regulation of enzymatic activity, posttranslational modifications, and apoptotic signaling.

p53 at the crossroad between mitochondrial reactive oxygen species and necroptosis

p53 is a redox-sensitive transcription factor that can regulate multiple cell death programs through different signaling pathways. In this review, we assess the role of p53 in the regulation of necroptosis, a programmed form of lytic cell death highly involved in the pathophysiology of multiple diseases. In particular, we focus on the role of mitochondrial reactive oxygen species (mtROS) as essential contributors to modulate necroptosis execution through p53. The enhanced generation of mtROS during necroptosis is critical for the correct interaction between receptor-interacting serine/threonine-protein kinase 1 (RIPK1) and 3 (RIPK3), two key components of the functional necrosome. p53 controls the occurrence of necroptosis by modulating the levels of mitochondrial H2O2 via peroxiredoxin 3 and sulfiredoxin. Furthermore, in response to increased levels of H2O2, p53 upregulates the long non-coding RNA necrosis-related factor, favoring the translation of RIPK1 and RIPK3. In parallel, a fraction of cytosolic p53 migrates into mitochondria, a process notably involved in necroptosis execution via its interaction with the mitochondrial permeability transition pore. In conclusion, p53 is located at the intersection between mtROS and the necroptosis machinery, making it a key protein to orchestrate redox signaling during necroptosis.

Lipid metabolic reprogramming in tumor microenvironment: from mechanisms to therapeutics

Lipid metabolic reprogramming is an emerging hallmark of cancer. In order to sustain uncontrolled proliferation and survive in unfavorable environments that lack oxygen and nutrients, tumor cells undergo metabolic transformations to exploit various ways of acquiring lipid and increasing lipid oxidation. In addition, stromal cells and immune cells in the tumor microenvironment also undergo lipid metabolic reprogramming, which further affects tumor functional phenotypes and immune responses. Given that lipid metabolism plays a critical role in supporting cancer progression and remodeling the tumor microenvironment, targeting the lipid metabolism pathway could provide a novel approach to cancer treatment. This review seeks to: (1) clarify the overall landscape and mechanisms of lipid metabolic reprogramming in cancer, (2) summarize the lipid metabolic landscapes within stromal cells and immune cells in the tumor microenvironment, and clarify their roles in tumor progression, and (3) summarize potential therapeutic targets for lipid metabolism, and highlight the potential for combining such approaches with other anti-tumor therapies to provide new therapeutic opportunities for cancer patients.

Characterization of the metabolic alteration-modulated tumor microenvironment mediated by TP53 mutation and hypoxia

BACKGROUND

TP53 mutation and hypoxia play an essential role in cancer progression. However, the metabolic reprogramming and tumor microenvironment (TME) heterogeneity mediated by them are still not fully understood.

METHODS

The multi-omics data of 32 cancer types and immunotherapy cohorts were acquired to comprehensively characterize the metabolic reprogramming pattern and the TME across cancer types and explore immunotherapy candidates. An assessment model for metabolic reprogramming was established by integration of multiple machine learning methods, including lasso regression, neural network, elastic network, and survival support vector machine (SVM). Pharmacogenomics analysis and in vitro assay were conducted to identify potential therapeutic drugs.

RESULTS

First, we identified metabolic subtype A (hypoxia-TP53 mutation subtype) and metabolic subtype B (non-hypoxia-TP53 wildtype subtype) in hepatocellular carcinoma (HCC) and showed that metabolic subtype A had an "immune inflamed" microenvironment. Next, we established an assessment model for metabolic reprogramming, which was more effective compared to the traditional prognostic indicators. Then, we identified a potential targeting drug, teniposide. Finally, we performed the pan-cancer analysis to illustrate the role of metabolic reprogramming in cancer and found that the metabolic alteration (MA) score was positively correlated with tumor mutational burden (TMB), neoantigen load, and homologous recombination deficiency (HRD) across cancer types. Meanwhile, we demonstrated that metabolic reprogramming mediated a potential immunotherapy-sensitive microenvironment in bladder cancer and validated it in an immunotherapy cohort.

CONCLUSION

Metabolic alteration mediated by hypoxia and TP53 mutation is associated with TME modulation and tumor progression across cancer types. In this study, we analyzed the role of metabolic alteration in cancer and propose a predictive model for cancer prognosis and immunotherapy responsiveness. We also explored a potential therapeutic drug, teniposide.

PBX3 promotes pentose phosphate pathway and colorectal cancer progression by enhancing G6PD expression

Metabolic reprogramming is a hallmark of cancers crucial for fulfilling the needs of energy, building blocks, and antioxidants to support tumor cells' rapid proliferation and to cope with the harsh microenvironment. Pre-B-cell leukemia transcription factor 3 (PBX3) is a member of the PBX family whose expression is up-regulated in various tumors, however, whether it is involved in tumor cell metabolic reprogramming remains unclear. Herein, we report that PBX3 is a positive regulator of glucose-6-phosphate dehydrogenase (G6PD), the rate-limiting enzyme in the pentose phosphate pathway (PPP). PBX3 promoted G6PD transcriptional activity in tumor cells by binding directly to its promoter, leading to PPP stimulation and enhancing the production of nucleotides and NADPH, a crucial reductant, thereby promoting nucleic acid and lipid biosynthesis while decreasing intracellular reactive oxygen species levels. The PBX3/G6PD axis also promoted tumorigenic potential in vitro and in vivo. Collectively, these findings reveal a novel function of PBX3 as a regulator of G6PD, linking its oncogenic activity with tumor cell metabolic reprogramming, especially PPP. Furthermore, our results suggested that PBX3 is a potential target for metabolic-based anti-tumor therapeutic strategies.

Pan-cancer analysis reveals that G6PD is a prognostic biomarker and therapeutic target for a variety of cancers

BACKGROUND

Despite accumulating evidence revealing that Glucose-6-phosphate dehydrogenase (G6PD) is highly expressed in many tumor tissues and plays a remarkable role in cancer tumorigenesis and progression, there is still a lack of G6PD pan-cancer analysis. This study was designed to analyze the expression status and prognostic significance of G6PD in pan-cancer.

METHODS

G6PD expression data were obtained from multiple data resources including the Genotype-Tissue Expression, the Cancer Genome Atlas, and the Tumor Immunity Estimation Resource. These data were used to assess the G6PD expression, prognostic value, and clinical characteristics. The ESTIMATE algorithms were used to analyze the association between G6PD expression and immune-infiltrating cells and the tumor microenvironment. The functional enrichment analysis was also performed across pan-cancer. In addition, the GDSC1 database containing 403 drugs was utilized to explore the relationship between drug sensitivity and G6PD expression levels. Furthermore, we also performed clinical validation and in vitro experiments to further validate the role of G6PD in hepatocellular carcinoma (HCC) cells and its correlation with prognosis. The R software was used for statistical analysis and data visualization.

RESULTS

G6PD expression was upregulated in most cancers compared to their normal counterparts. The study also revealed that G6PD expression was a prognostic indicator and high levels of G6PD expression were correlated with worse clinical prognosis including overall survival, disease-specific survival, and progression-free interval in multiple cancers. Furthermore, the G6PD level was also related to cancer immunity infiltration in most of the cancers, especially in KIRC, LGG, and LIHC. In addition to this, G6PD expression was positively related to pathological stages of KIRP, BRCA, KIRC, and LIHC. Functional analysis and protein-protein interactions network results revealed that G6PD was involved in metabolism-related activities, immune responses, proliferation, and apoptosis. Drug sensitivity analysis showed that IC50 values of most identified anti-cancer drugs were positively correlated with the G6PD expression. Notably, in vitro functional validation showed that G6PD knockdown attenuated the phenotypes of proliferation in HCC.

CONCLUSION

G6PD may serve as a potential prognostic biomarker for cancers and may be a potential therapeutic target gene for tumor therapy.

Genetics of enzymatic dysfunctions in metabolic disorders and cancer

Inherited metabolic disorders arise from mutations in genes involved in the biogenesis, assembly, or activity of metabolic enzymes, leading to enzymatic deficiency and severe metabolic impairments. Metabolic enzymes are essential for the normal functioning of cells and are involved in the production of amino acids, fatty acids and nucleotides, which are essential for cell growth, division and survival. When the activity of metabolic enzymes is disrupted due to mutations or changes in expression levels, it can result in various metabolic disorders that have also been linked to cancer development. However, there remains much to learn regarding the relationship between the dysregulation of metabolic enzymes and metabolic adaptations in cancer cells. In this review, we explore how dysregulated metabolism due to the alteration or change of metabolic enzymes in cancer cells plays a crucial role in tumor development, progression, metastasis and drug resistance. In addition, these changes in metabolism provide cancer cells with a number of advantages, including increased proliferation, resistance to apoptosis and the ability to evade the immune system. The tumor microenvironment, genetic context, and different signaling pathways further influence this interplay between cancer and metabolism. This review aims to explore how the dysregulation of metabolic enzymes in specific pathways, including the urea cycle, glycogen storage, lysosome storage, fatty acid oxidation, and mitochondrial respiration, contributes to the development of metabolic disorders and cancer. Additionally, the review seeks to shed light on why these enzymes represent crucial potential therapeutic targets and biomarkers in various cancer types.

Cross-talk between DNA damage response and the central carbon metabolic network underlies selective vulnerability of Purkinje neurons in ataxia-telangiectasia

Cerebellar ataxia is often the first and irreversible outcome in the disease of ataxia-telangiectasia (A-T), as a consequence of selective cerebellar Purkinje neuronal degeneration. A-T is an autosomal recessive disorder resulting from the loss-of-function mutations of the ataxia-telangiectasia-mutated ATM gene. Over years of research, it now becomes clear that functional ATM-a serine/threonine kinase protein product of the ATM gene-plays critical roles in regulating both cellular DNA damage response and central carbon metabolic network in multiple subcellular locations. The key question arises is how cerebellar Purkinje neurons become selectively vulnerable when all other cell types in the brain are suffering from the very same defects in ATM function. This review intended to comprehensively elaborate the unexpected linkages between these two seemingly independent cellular functions and the regulatory roles of ATM involved, their integrated impacts on both physical and functional properties, hence the introduction of selective vulnerability to Purkinje neurons in the disease will be addressed.

A mitotic NADPH upsurge promotes chromosome segregation and tumour progression in aneuploid cancer cells

Redox metabolites have been observed to fluctuate through the cell cycle in cancer cells, but the functional impacts of such metabolic oscillations remain unknown. Here, we uncover a mitosis-specific nicotinamide adenine dinucleotide phosphate (NADPH) upsurge that is essential for tumour progression. Specifically, NADPH is produced by glucose 6-phosphate dehydrogenase (G6PD) upon mitotic entry, which neutralizes elevated reactive oxygen species (ROS) and prevents ROS-mediated inactivation of mitotic kinases and chromosome missegregation. Mitotic activation of G6PD depends on the phosphorylation of its co-chaperone protein BAG3 at threonine 285, which results in dissociation of inhibitory BAG3. Blocking BAG3T285 phosphorylation induces tumour suppression. A mitotic NADPH upsurge is present in aneuploid cancer cells with high levels of ROS, while nearly unobservable in near-diploid cancer cells. High BAG3T285 phosphorylation is associated with worse prognosis in a cohort of patients with microsatellite-stable colorectal cancer. Our study reveals that aneuploid cancer cells with high levels of ROS depend on a G6PD-mediated NADPH upsurge in mitosis to protect them from ROS-induced chromosome missegregation.

Rewired Metabolism Caused by the Oncogenic Deregulation of MYC as an Attractive Therapeutic Target in Cancers

MYC is one of the most deregulated oncogenes on multiple levels in cancer. As a node transcription factor, MYC plays a diverse regulatory role in many cellular processes, including cell cycle and metabolism, both in physiological and pathological conditions. The relentless growth and proliferation of tumor cells lead to an insatiable demand for energy and nutrients, which requires the rewiring of cellular metabolism. As MYC can orchestrate all aspects of cellular metabolism, its altered regulation plays a central role in these processes, such as the Warburg effect, and is a well-established hallmark of cancer development. However, our current knowledge of MYC suggests that its spatial- and concentration-dependent contribution to tumorigenesis depends more on changes in the global or relative expression of target genes. As the direct targeting of MYC is proven to be challenging due to its relatively high toxicity, understanding its underlying regulatory mechanisms is essential for the development of tumor-selective targeted therapies. The aim of this review is to comprehensively summarize the diverse forms of MYC oncogenic deregulation, including DNA-, transcriptional- and post-translational level alterations, and their consequences for cellular metabolism. Furthermore, we also review the currently available and potentially attractive therapeutic options that exploit the vulnerability arising from the metabolic rearrangement of MYC-driven tumors.

The crisscross between p53 and metabolism in cancer

As the guardian of the genome, p53 is well known for its tumor suppressor function in humans, controlling cell proliferation, senescence, DNA repair and cell death in cancer through transcriptional and non-transcriptional activities. p53 is the most frequently mutated gene in human cancer, but how its mutation or depletion leads to tumorigenesis still remains poorly understood. Recently, there has been increasing evidence that p53 plays a vital role in regulating cellular metabolism as well as in metabolic adaptation to nutrient starvation. In contrast, mutant p53 proteins, especially those harboring missense mutations, have completely different functions compared to wild-type p53. In this review, we briefly summarize what is known about p53 mediating anabolic and catabolic metabolism in cancer, and in particular discuss recent findings describing how metabolites regulate p53 functions. To illustrate the variability and complexity of p53 function in metabolism, we will also review the differential regulation of metabolism by wild-type and mutant p53.

Chlamydia Infection Remodels Host Cell Mitochondria to Alter Energy Metabolism and Subvert Apoptosis

Chlamydia infection represents an important cause for concern for public health worldwide. Chlamydial infection of the genital tract in females is mostly asymptomatic at the early stage, often manifesting as mucopurulent cervicitis, urethritis, and salpingitis at the later stage; it has been associated with female infertility, spontaneous abortion, ectopic pregnancy, and cervical cancer. As an obligate intracellular bacterium, Chlamydia depends heavily on host cells for nutrient acquisition, energy production, and cell propagation. The current review discusses various strategies utilized by Chlamydia in manipulating the cell metabolism to benefit bacterial propagation and survival through close interaction with the host cell mitochondrial and apoptotic pathway molecules.

The Metabolic Landscape of Breast Cancer and Its Therapeutic Implications

Breast cancer is the most common malignant tumor globally as of 2020 and remains the second leading cause of cancer-related death among female individuals worldwide. Metabolic reprogramming is well recognized as a hallmark of malignancy owing to the rewiring of multiple biological processes, notably, glycolysis, oxidative phosphorylation, pentose phosphate pathway, as well as lipid metabolism, which support the demands for the relentless growth of tumor cells and allows distant metastasis of cancer cells. Breast cancer cells are well documented to reprogram their metabolism via mutations or inactivation of intrinsic factors such as c-Myc, TP53, hypoxia-inducible factor, and the PI3K/AKT/mTOR pathway or crosstalk with the surrounding tumor microenvironments, including hypoxia, extracellular acidification and interaction with immune cells, cancer-associated fibroblasts, and adipocytes. Furthermore, altered metabolism contributes to acquired or inherent therapeutic resistance. Therefore, there is an urgent need to understand the metabolic plasticity underlying breast cancer progression as well as to dictate metabolic reprogramming that accounts for the resistance to standard of care. This review aims to illustrate the altered metabolism in breast cancer and its underlying mechanisms, as well as metabolic interventions in breast cancer treatment, with the intention to provide strategies for developing novel therapeutic treatments for breast cancer.

p53 protects against alcoholic fatty liver disease via ALDH2 inhibition

The tumor suppressor p53 is critical for tumor suppression, but the regulatory role of p53 in alcohol-induced fatty liver remains unclear. Here, we show a role for p53 in regulating ethanol metabolism via acetaldehyde dehydrogenase 2 (ALDH2), a key enzyme responsible for the oxidization of alcohol. By repressing ethanol oxidization, p53 suppresses intracellular levels of acetyl-CoA and histone acetylation, leading to the inhibition of the stearoyl-CoA desaturase-1 (SCD1) gene expression. Mechanistically, p53 directly binds to ALDH2 and prevents the formation of its active tetramer and indirectly limits the production of pyruvate that promotes the activity of ALDH2. Notably, p53-deficient mice exhibit increased lipid accumulation, which can be reversed by ALDH2 depletion. Moreover, liver-specific knockdown of SCD1 alleviates ethanol-induced hepatic steatosis caused by p53 loss. By contrast, overexpression of SCD1 in liver promotes ethanol-induced fatty liver development in wild-type mice, while it has a mild effect on p53-/- or ALDH2-/- mice. Overall, our findings reveal a previously unrecognized function of p53 in alcohol-induced fatty liver and uncover pyruvate as a natural regulator of ALDH2.

On the Role of Glycolysis in Early Tumorigenesis-Permissive and Executioner Effects

Reprogramming energy production from mitochondrial respiration to glycolysis is now considered a hallmark of cancer. When tumors grow beyond a certain size they give rise to changes in their microenvironment (e.g., hypoxia, mechanical stress) that are conducive to the upregulation of glycolysis. Over the years, however, it has become clear that glycolysis can also associate with the earliest steps of tumorigenesis. Thus, many of the oncoproteins most commonly involved in tumor initiation and progression upregulate glycolysis. Moreover, in recent years, considerable evidence has been reported suggesting that upregulated glycolysis itself, through its enzymes and/or metabolites, may play a causative role in tumorigenesis, either by acting itself as an oncogenic stimulus or by facilitating the appearance of oncogenic mutations. In fact, several changes induced by upregulated glycolysis have been shown to be involved in tumor initiation and early tumorigenesis: glycolysis-induced chromatin remodeling, inhibition of premature senescence and induction of proliferation, effects on DNA repair, O-linked N-acetylglucosamine modification of target proteins, antiapoptotic effects, induction of epithelial-mesenchymal transition or autophagy, and induction of angiogenesis. In this article we summarize the evidence that upregulated glycolysis is involved in tumor initiation and, in the following, we propose a mechanistic model aimed at explaining how upregulated glycolysis may play such a role.

Sirtuin1-p53: a potential axis for cancer therapy

Sirtuin1 (SIRT1) is a conserved nicotinamide adenine dinucleotide (NAD⁺)-dependent histone deacetylase that plays key roles in a range of cellular events, including the maintenance of genome stability, gene regulation, cell proliferation, and apoptosis. P53 is one of the most studied tumor suppressors and the first identified non-histone target of SIRT1. SIRT1 deacetylates p53 in a NAD⁺-dependent manner and inhibits its transcriptional activity, thus exerting action on a series of pathways related to tissue homeostasis and various pathological states. The SIRT1-p53 axis is thought to play a central role in tumorigenesis. Although SIRT1 was initially identified as a tumor promoter, evidence now indicates that SIRT1 may also act as a tumor suppressor. This seemingly contradictory evidence indicates that the functionality of SIRT1 may be dictated by different cell types and intracellular localization patterns. In this review, we summarize recent evidence relating to the interactions between SIRT1 and p53 and discuss the relative roles of these two molecules with regards to cancer-associated cellular events. We also provide an overview of current knowledge of SIRT1-p53 signaling in tumorigenesis. Given the vital role of the SIRT1-p53 pathway, targeting this axis may provide promising strategies for the treatment of cancer.

Pentose Pathway Activation Is Superior to Increased Glycolysis for Therapeutic Angiogenesis in Peripheral Arterial Disease

Background In endothelial cells (ECs), glycolysis, regulated by PFKFB3 (6-phosphofructo-2-kinase/fructose-2,6-biphosphatase, isoform-3), is the major metabolic pathway for ATP generation. In preclinical peripheral artery disease models, VEGF165a (vascular endothelial growth factor165a) and microRNA-93 both promote angiogenesis. Methods and Results Mice following hind-limb ischemia (HLI) and ECs with, and without, hypoxia and serum starvation were examined with, and without, microRNA-93 and VEGF165a. Post-HLI perfusion recovery was monitored. EC metabolism was studied using seahorse assay, and the expression and activity of major metabolism genes were assessed. Reactive oxygen species levels and EC permeability were evaluated. C57Bl/6J mice generated a robust angiogenic response to HLI, with ECs from ischemic versus nonischemic muscle demonstrating no increase in glycolysis. Balb/CJ mice generated a poor angiogenic response post-HLI; ischemic versus nonischemic ECs demonstrated significant increase in glycolysis. MicroRNA-93-treated Balb/CJ mice post-HLI showed better perfusion recovery, with ischemic versus nonischemic ECs showing no increase in glycolysis. VEGF165a-treated Balb/CJ mice post-HLI showed no improvement in perfusion recovery with ischemic versus nonischemic ECs showing significant increase in glycolysis. ECs under hypoxia and serum starvation upregulated PFKFB3. In ECs under hypoxia and serum starvation, VEGF165a versus control significantly upregulated PFKFB3 and glycolysis, whereas miR-93 versus control demonstrated no increase in PFKFB3 or glycolysis. MicroRNA-93 versus VEGF165a upregulated glucose-6-phosphate dehydrogenase expression and activity, activating the pentose phosphate pathway. MicroRNA-93 versus control increased reduced nicotinamide adenine dinucleotide phosphate and virtually eliminated the increase in reactive oxygen species. In ECs under hypoxia and serum starvation, VEGF165a significantly increased and miR-93 decreased EC permeability. Conclusions In peripheral artery disease, activation of the pentose phosphate pathway to promote angiogenesis may offer potential therapeutic advantages.

Dissecting the roles and clinical potential of YY1 in the tumor microenvironment

Yin-Yang 1 (YY1) is a member of the GLI-Kruppel family of zinc finger proteins and plays a vital dual biological role in cancer as an oncogene or a tumor suppressor during tumorigenesis and tumor progression. The tumor microenvironment (TME) is identified as the “soil” of tumor that has a critical role in both tumor growth and metastasis. Many studies have found that YY1 is closely related to the remodeling and regulation of the TME. Herein, we reviewed the expression pattern of YY1 in tumors and summarized the function and mechanism of YY1 in regulating tumor angiogenesis, immune and metabolism. In addition, we discussed the potential value of YY1 in tumor diagnosis and treatment and provided a novel molecular strategy for the clinical diagnosis and treatment of tumors.

The p52-ZER6/G6PD axis alters aerobic glycolysis and promotes tumor progression by activating the pentose phosphate pathway

Abnormal glucose metabolism is a highlight of tumor metabolic reprogramming and is closely related to the development of malignancies. p52-ZER6, a C₂H₂-type zinc finger protein, promotes cell proliferation and tumorigenesis. However, its role in the regulation of biological and pathological functions remains poorly understood. Here, we examined the role of p52-ZER6 in tumor cell metabolic reprogramming. Specifically, we demonstrated that p52-ZER6 promotes tumor glucose metabolic reprogramming by positively regulating the transcription of glucose-6-phosphate dehydrogenase (G6PD), the rate-limiting enzyme in the pentose phosphate pathway (PPP). By activating the PPP, p52-ZER6 was found to enhance the production of nucleotides and nicotinamide adenine dinucleotide phosphate, thereby providing tumor cells with the building blocks of ribonucleic acids and cellular reductants for reactive oxygen species scavenging, which subsequently promotes tumor cell proliferation and viability. Importantly, p52-ZER6 promoted PPP-mediated tumorigenesis in a p53-independent manner. Taken together, these findings reveal a novel role for p52-ZER6 in regulating G6PD transcription via a p53-independent process, ultimately resulting in tumor cell metabolic reprogramming and tumorigenesis. Our results suggest that p52-ZER6 is a potential target for the diagnosis and treatment of tumors and metabolic disorders.

Aflatoxin B1 exposure triggers hepatic lipotoxicity via p53 and perilipin 2 interaction-mediated mitochondria-lipid droplet contacts: An in vitro and in vivo assessment

Aflatoxin B1 (AFB1) is one of the most toxic mycotoxins widely found in food contaminants, and its target organ is the liver. It poses a major food security and public health threat worldwide. However, the lipotoxicity mechanism of AFB1 exposure-induced liver injury remains unclear and requires further elucidation. Herein, we investigated the potential hepatic lipotoxicity of AFB1 exposure using in vitro and in vivo models to assess the public health hazards of high dietary AFB1 exposure. We demonstrated that low-dose of AFB1 (1.25 μM for 48 h, about one-fifth of the IC50 in HepG2 and HepaRG cells, IC50 are 5.995 μM and 5.266 μM, respectively) exposure significantly induced hepatic lipotoxicity, including abnormal lipid droplets (LDs) growth, mitochondria-LDs contacts increase, lipophagy disruption, and lipid accumulation. Mechanistically, we showed that AFB1 exposure promoted the mitochondrial p53 (mito-p53) and LDs-associated protein perilipin 2 (PLIN2) interaction-mediated mitochondria-LDs contacts, resulting in lipid accumulation in hepatocytes. Mito-p53-targeted inhibition, knockdown of PLIN2, and rapamycin application efficiently promoted the lysosome-dependent lipophagy and alleviated the hepatic lipotoxicity and liver injury induced by AFB1 exposure. Overall, our study found that mito-p53 and PLIN2 interaction mediates three organelles-mitochondria, LDs, and lysosomal networks to regulate lipid homeostasis in AFB1 exposure-induced hepatotoxicity, revealing how this unique trio of organelles works together and provides a novel insight into the targeted intervention in inter-organelle lipid sensing and trafficking for alleviating hazardous materials-induced hepatic lipotoxicity.

LPLUNC1 reduces glycolysis in nasopharyngeal carcinoma cells through the PHB1-p53/c-Myc axis

Cancer cells prefer glycolysis to support their proliferation. Our previous studies have shown that the long palate, lung, and nasal epithelial cell clone 1 (LPLUNC1) can upregulate prohibitin 1 (PHB1) expression to inhibit the proliferation of nasopharyngeal carcinoma (NPC) cells. Given that PHB1 is an important regulator of cell energy metabolism, we explored whether and how LPLUNC1 regulated glucose glycolysis in NPC cells. LPLUNC1 or PHB1 overexpression decreased glycolysis and increased oxidative phosphorylation (OXPHOS)-related protein expression in NPC cells, promoting phosphorylated PHB1 nuclear translocation through 14-3-3σ. LPLUNC1 overexpression also increased p53 but decreased c-Myc expression in NPC cells, which were crucial for the decrease in glycolysis and increase in OXPHOS-related protein expression induced by LPLUNC1 overexpression. Finally, we found that treatment with all-trans retinoic acid (ATRA) reduced the viability and clonogenicity of NPC cells, decreased glycolysis, and increased OXPHOS-related protein expression by enhancing LPLUNC1 expression in NPC cells. Therefore, the LPLUNC1-PHB1-p53/c-Myc axis decreased glycolysis in NPC cells, and ATRA upregulated LPLUNC1 expression, ATRA maybe a promising drug for the treatment of NPC.

Targeting p53 pathways: mechanisms, structures, and advances in therapy

The TP53 tumor suppressor is the most frequently altered gene in human cancers, and has been a major focus of oncology research. The p53 protein is a transcription factor that can activate the expression of multiple target genes and plays critical roles in regulating cell cycle, apoptosis, and genomic stability, and is widely regarded as the "guardian of the genome". Accumulating evidence has shown that p53 also regulates cell metabolism, ferroptosis, tumor microenvironment, autophagy and so on, all of which contribute to tumor suppression. Mutations in TP53 not only impair its tumor suppressor function, but also confer oncogenic properties to p53 mutants. Since p53 is mutated and inactivated in most malignant tumors, it has been a very attractive target for developing new anti-cancer drugs. However, until recently, p53 was considered an "undruggable" target and little progress has been made with p53-targeted therapies. Here, we provide a systematic review of the diverse molecular mechanisms of the p53 signaling pathway and how TP53 mutations impact tumor progression. We also discuss key structural features of the p53 protein and its inactivation by oncogenic mutations. In addition, we review the efforts that have been made in p53-targeted therapies, and discuss the challenges that have been encountered in clinical development.

lncRNA ELFN1-AS1 promotes proliferation, migration and invasion and suppresses apoptosis in colorectal cancer cells by enhancing G6PD activity

Tumour cells change their metabolic patterns to support high proliferation rates and cope with oxidative stress. The lncRNA ELFN1-AS1 is highly expressed in a wide range of cancers and is essential to the proliferation and apoptosis of tumour cells. Nevertheless, its function in the metabolic reprogramming of tumour cells is unclear. Here we show that ELFN1-AS1 promotes glucose consumption as well as lactate and NADPH production. Database searching, bioinformatics analysis, RNA immunoprecipitation (RIP) and RNA pull-down assays show that ELFN1-AS1 enhances glucose-6-phosphate dehydrogenase ( G6PD) expression and activates the pentose phosphate pathway (PPP) by promoting TP53 degradation. In addition, luciferase reporter assay and chromatin immunoprecipitation (ChIP) show that YY1 binds to the ELFN1-AS1 promoter to promote transcriptional activation of ELFN1-AS1. Consistent with the in vitro experiments, knockdown of ELFN1-AS1 impedes the growth of tumours transplanted into mice by inhibiting the expression of G6PD. In conclusion, this study reveals that ELFN1-AS1 activates the PPP, and validates the regulatory role of the YY1/ ELFN1-AS1/ TP53/ G6PD axis in colorectal cancer.

Cuproptosis: p53-regulated metabolic cell death?

Cuproptosis is a novel type of copper-induced cell death that primarily occurs in cells that utilize oxidative phosphorylation as the main metabolic pathway to produce energy. Copper directly associates with the lipoylated proteins of the tricarboxylic acid cycle, leading to the disulfide-bond-dependent aggregation of these lipoylated proteins, destabilization of the iron-sulfur cluster proteins, and consequent proteotoxic stress. Cancer cells prefer glycolysis (Warburg effect) to oxidative phosphorylation for producing intermediate metabolites and energy, thereby achieving resistance to cuproptosis. Interestingly, the tumor suppressor p53 is a crucial metabolic regulator that inhibits glycolysis and drives a metabolic switch towards oxidative phosphorylation in cancer cells. Additionally, p53 regulates the biogenesis of iron-sulfur clusters and the copper chelator glutathione, which are two critical components of the cuproptotic pathway, suggesting that this tumor suppressor might play a role in cuproptosis. Furthermore, the possible roles of mutant p53 in regulating cuproptosis are discussed. In this essay, we review the recent progress in the understanding of the mechanism underlying cuproptosis, revisit the roles of p53 in metabolic regulation and iron-sulfur cluster and glutathione biosynthesis, and propose several potential mechanisms for wild-type and mutant p53-mediated cuproptosis regulation.

Metabolic reprogramming in colorectal cancer: regulatory networks and therapy

With high prevalence and mortality, together with metabolic reprogramming, colorectal cancer is a leading cause of cancer-related death. Metabolic reprogramming gives tumors the capacity for long-term cell proliferation, making it a distinguishing feature of cancer. Energy and intermediate metabolites produced by metabolic reprogramming fuel the rapid growth of cancer cells. Aberrant metabolic enzyme-mediated tumor metabolism is regulated at multiple levels. Notably, tumor metabolism is affected by nutrient levels, cell interactions, and transcriptional and posttranscriptional regulation. Understanding the crosstalk between metabolic enzymes and colorectal carcinogenesis factors is particularly important to advance research for targeted cancer therapy strategies via the investigation into the aberrant regulation of metabolic pathways. Hence, the abnormal roles and regulation of metabolic enzymes in recent years are reviewed in this paper, which provides an overview of targeted inhibitors for targeting metabolic enzymes in colorectal cancer that have been identified through tumor research or clinical trials.

p53 promotes peroxisomal fatty acid β-oxidation to repress purine biosynthesis and mediate tumor suppression

The metabolic pathways through which p53 functions as a potent tumor suppressor are incompletely understood. Here we report that, by associating with the Vitamin D receptor (VDR), p53 induces numerous genes encoding enzymes for peroxisomal fatty acid β-oxidation (FAO). This leads to increased cytosolic acetyl-CoA levels and acetylation of the enzyme 5-Aminoimidazole-4-Carboxamide Ribonucleotide Formyltransferase/IMP Cyclohydrolase (ATIC), which catalyzes the last two steps in the purine biosynthetic pathway. This acetylation step, mediated by lysine acetyltransferase 2B (KAT2B), occurs at ATIC Lys 266, dramatically inhibits ATIC activity, and inversely correlates with colorectal cancer (CRC) tumor growth in vitro and in vivo, and acetylation of ATIC is downregulated in human CRC samples. p53-deficient CRCs with high levels of ATIC is more susceptible to ATIC inhibition. Collectively, these findings link p53 to peroxisomal FAO, purine biosynthesis, and CRC pathogenesis in a manner that is regulated by the levels of ATIC acetylation.

MARS2 drives metabolic switch of non-small-cell lung cancer cells via interaction with MCU

Mitochondrial methionyl-tRNA synthetase (MARS2) canonically mediates the formation of fMet-tRNA_i^fMet for mitochondrial translation initiation. Mitochondrial calcium uniporter (MCU) is a major gate of Ca²⁺ flux from cytosol into the mitochondrial matrix. We found that MARS2 interacts with MCU and stimulates mitochondrial Ca²⁺ influx. Methionine binding to MARS2 would act as a molecular switch that regulates MARS2-MCU interaction. Endogenous knockdown of MARS2 attenuates mitochondrial Ca²⁺ influx and induces p53 upregulation through the Ca²⁺-dependent CaMKII/CREB signaling. Subsequently, metabolic rewiring from glycolysis into pentose phosphate pathway is triggered and cellular reactive oxygen species level decreases. This metabolic switch induces inhibition of epithelial-mesenchymal transition (EMT) via cellular redox regulation. Expression of MARS2 is regulated by ZEB1 transcription factor in response to Wnt signaling. Our results suggest the mechanisms of mitochondrial Ca²⁺ uptake and metabolic control of cancer that are exerted by the key factors of the mitochondrial translational machinery and Ca²⁺ homeostasis.

Targeting glucose-6-phosphate dehydrogenase by 6-AN induces ROS-mediated autophagic cell death in breast cancer

Dysregulation of G6PD involved in the pentose phosphate pathway (PPP) is known to promote tumorigenesis. The PPP plays a pivotal role in meeting the anabolic demands of cancer cells. However, the detailed underlying molecular mechanisms of targeting the G6PD-regulated PPP in breast cancer remain unclear. In this study, we aimed to elucidate the molecular pathways mediating the effects of G6PD on cancer progression. Clinical sample analysis found that the expression of G6PD in breast cancer patients was higher than that in normal controls, and patients with higher G6PD expression had poor survival. Gene knockdown or inhibition of G6PD by 6-AN in MCF-7 and MDA-MB-231 cells significantly decreased cell viability, migration, and colony formation ability. G6PD enzyme activity was inhibited by 6-AN treatment, which caused a transient upregulation of ROS. The elevated ROS was independent of cell apoptosis and thus associated with abnormal activated autophagy. Accumulated ROS levels induced autophagic cell death in breast cancer. Inhibition of G6PD suppresses tumour growth in preclinical models of breast cancer. Our results indicate that targeting the G6PD-regulated PPP could restrain tumours in vitro and in vivo, inhibiting G6PD caused cell death by over-activating autophagy, therefore leading to inhibited proliferation and tumour formation.

Liver-specific deletion of microRNA-34a alleviates ductular reaction and liver fibrosis during experimental cholestasis

Primary sclerosing cholangitis (PSC) is a chronic liver disease characterized by inflammatory responses and fibrotic scar formation leading to cholestasis. Ductular reaction and liver fibrosis are typical liver changes seen in human PSC and cholestasis patients. The current study aimed to clarify the role of liver-specific microRNA-34a in the cholestasis-associated ductular reaction and liver fibrosis. We demonstrated that miR-34a expression was significantly increased in human PSC livers along with the enhanced ductular reaction, cellular senescence, and liver fibrosis. A liver-specific miR-34a knockout mouse was established by crossing floxed miR-34a mice with albumin-promoter-driven Cre mice. Bile duct ligation (BDL) induced liver injury characterized by necrosis, fibrosis, and immune cell infiltration. In contrast, liver-specific miR-34a knockout in BDL mice resulted in decreased biliary ductular pathology associated with the reduced cholangiocyte senescence and fibrotic responses. The miR-34a-mediated ductular reactions may be functioning through Sirt-1-mediated senescence and fibrosis. The hepatocyte-derived conditioned medium promoted LPS-induced fibrotic responses and senescence in cholangiocytes, and miR-34a inhibitor suppressed these effects, further supporting the involvement of paracrine regulation. In conclusion, we demonstrated that liver-specific miR-34a plays an important role in ductular reaction and fibrotic responses in a BDL mouse model of cholestatic liver disease.

A role of cytoplasmic p53 in the regulation of metabolism shown by bat-mimicking p53 NLS mutant mice

The transcription factor p53 suppresses tumorigenesis via a wide-ranging, concerted set of functions. Although several studies have identified cytoplasmic, transcription-independent functions of p53, the biological relevance of these activities has not been fully elucidated, particularly in vivo. Here, we generated a mouse model with a p53^K316P mutation, which mimics a naturally occurring p53 nuclear localization signal (NLS) change observed in bat species. We find that the p53^K316P mutation increases cytoplasmic localization of p53 and promotes a pleiotropic metabolic phenotype that includes increased adiposity, increased de novo lipogenesis, and decreased lactate generation. Mechanistic studies show that, independent of its transactivation function, p53^K316P interacts with lactate dehydrogenase B (LDHB) and alters the composition and enzymatic activities of LDH complex favoring pyruvate generation and hindering lactate production. Overall, the study identifies a role for cytoplasmic p53 in the regulation of metabolism that favors energy generation and storage.

A High-Throughput Sequencing Data-Based Classifier Reveals the Metabolic Heterogeneity of Hepatocellular Carcinoma

Metabolic heterogeneity plays a key role in poor outcomes in malignant tumors, but its role in hepatocellular carcinoma (HCC) remains largely unknown. In the present study, we aim to disentangle the metabolic heterogeneity features of HCC by developing a classification system based on metabolism pathway activities in high-throughput sequencing datasets. As a result, HCC samples were classified into two distinct clusters: cluster 1 showed high levels of glycolysis and pentose phosphate pathway activity, while cluster 2 exhibited high fatty acid oxidation and glutaminolysis status. This metabolic reprogramming-based classifier was found to be highly correlated with several clinical variables, including overall survival, prognosis, TNM stage, and 𝛼-fetoprotein (AFP) expression. Of note, activated oncogenic pathways, a higher TP53 mutation rate, and increased stemness were also observed in cluster 1, indicating a causal relationship between metabolic reprogramming and carcinogenesis. Subsequently, distinct metabolism-targeted therapeutic strategies were proven in human HCC cell lines, which exhibit the same metabolic properties as corresponding patient samples based on this classification system. Furthermore, the metabolic patterns and effects of different types of cells in the tumor immune microenvironment were explored by referring to both bulk and single-cell data. It was found that malignant cells had the highest overall metabolic activities, which may impair the anti-tumor capacity of CD8+ T cells through metabolic competition, and this provided a potential explanation for why immunosuppressive cells had higher overall metabolic activities than those with anti-tumor functions. Collectively, this study established an HCC classification system based on the gene expression of energy metabolism pathways. Its prognostic and therapeutic value may provide novel insights into personalized clinical practice in patients with metabolic heterogeneity.

Targeting mutant p53-R248W reactivates WT p53 function and alters the onco-metabolic profile

TP53 is the most commonly mutated gene in cancer, and gain-of-function mutations have wide-ranging effects. Efforts to reactivate wild-type p53 function and inhibit mutant functions have been complicated by the variety of TP53 mutations. Identified from a screen, the NSC59984 compound has been shown to restore activity to mutant p53 in colorectal cancer cells. Here, we investigated its effects on esophageal adenocarcinoma cells with specific p53 hot-spot mutations. NSC59984 treatment of cells reactivated p53 transcriptional regulation, inducing mitochondrial intrinsic apoptosis. Analysis of its effects on cellular metabolism demonstrated increased utilization of the pentose phosphate pathway and inhibition of glycolysis at the fructose-1,6-bisphosphate to fructose 6-phosphate junction. Furthermore, treatment of cells with NSC59984 increased reactive oxygen species production and decreased glutathione levels; these effects were enhanced by the addition of buthionine sulfoximine and inhibited by N-acetyl cysteine. We found that the effects of NSC59984 were substantially greater in cells harboring the p53 R248W mutation. Overall, these findings demonstrate p53-dependent effects of NSC59984 on cellular metabolism, with increased activity in cells harboring the p53 R248W mutation. This research highlights the importance of defining the mutational status of a particular cancer to create a patient-centric strategy for the treatment of p53-driven cancers.

Polyploid/Multinucleated Giant and Slow-Cycling Cancer Cell Enrichment in Response to X-ray Irradiation of Human Glioblastoma Multiforme Cells Differing in Radioresistance and TP53/PTEN Status

Radioresistance compromises the efficacy of radiotherapy for glioblastoma multiforme (GBM), the most devastating and common brain tumor. The present study investigated the relationship between radiation tolerance and formation of polyploid/multinucleated giant (PGCC/MGCC) and quiescent/senescent slow-cycling cancer cells in human U-87, LN-229, and U-251 cell lines differing in TP53/PTEN status and radioresistance. We found significant enrichment in MGCC populations of U-87 and LN-229 cell lines, and generation of numerous small mononuclear (called Raju cells, or RJ cells) U-87-derived cells that eventually form cell colonies, in a process termed neosis, in response to X-ray irradiation (IR) at single acute therapeutic doses of 2-6 Gy. For the first time, single-cell high-content imaging and analysis of Ki-67- and EdU-coupled fluorescence demonstrated that the IR exposure dose-dependently augments two distinct GBM cell populations. Bifurcation of Ki-67 staining suggests fast-cycling and slow-cycling populations with a normal-sized nuclear area, and with an enlarged nuclear area, including one resembling the size of PGCC/MGCCs, that likely underlie the highest radioresistance and propensity for repopulation of U-87 cells. Proliferative activity and anchorage-independent survival of GBM cell lines seem to be related to neosis, low level of apoptosis, fraction of prematurely stress-induced senescent MGCCs, and the expression of p63 and p73, members of p53 family transcription factors, but not to the mutant p53. Collectively, our data support the importance of the TP53wt/PTENmut genotype for the maintenance of cycling radioresistant U-87 cells to produce a significant amount of senescent MGCCs as an IR stress-induced adaptation response to therapeutic irradiation doses.

More Than an Antioxidant: Role of Dietary Astaxanthin on Lipid and Glucose Metabolism in the Liver of Rainbow Trout (Oncorhynchus mykiss)

This study investigated the influence of dietary astaxanthin (AX) on glucose and lipid metabolism in rainbow trout liver. Two iso-nitrogenous and iso-lipidic diets were tested for 12 weeks in rainbow trout with an initial mean weight of 309 g. The S-ASTA diet was supplemented with 100 mg of synthetic AX per kg of feed, whereas the control diet (CTRL) had no AX. Fish fed the S-ASTA diet displayed lower neutral and higher polar lipids in the liver, associated with smaller hepatocytes and lower cytoplasm vacuolization. Dietary AX upregulated adipose triglyceride lipase (atgl), hormone-sensitive lipase (hsl2) and 1,2-diacylglycerol choline phosphotransferase (chpt), and downregulated diacylglycerol acyltransferase (dgat2), suggesting the AX's role in triacylglycerol (TAG) turnover and phospholipid (PL) synthesis. Dietary AX may also affect beta-oxidation with the upregulation of carnitine palmitoyltransferase 1 (cpt1α2). Although hepatic cholesterol levels were not affected, dietary AX increased gene expression of sterol regulatory element-binding protein 2 (srebp2). Dietary AX upregulated the expression of 6-phosphogluconate dehydrogenase (6pgdh) and downregulated pyruvate kinase (pkl). Overall, results suggest that dietary AX modulates the oxidative phase of the pentose phosphate pathway and the last step of glycolysis, affecting TAG turnover, β-oxidation, PL and cholesterol synthesis in rainbow trout liver.

Disorders of cancer metabolism: The therapeutic potential of cannabinoids

Abnormal energy metabolism, as one of the important hallmarks of cancer, was induced by multiple carcinogenic factors and tumor-specific microenvironments. It comprises aerobic glycolysis, de novo lipid biosynthesis, and glutamine-dependent anaplerosis. Considering that metabolic reprogramming provides various nutrients for tumor survival and development, it has been considered a potential target for cancer therapy. Cannabinoids have been shown to exhibit a variety of anticancer activities by unclear mechanisms. This paper first reviews the recent progress of related signaling pathways (reactive oxygen species (ROS), AMP-activated protein kinase (AMPK), mitogen-activated protein kinases (MAPK), phosphoinositide 3-kinase (PI3K), hypoxia-inducible factor-1alpha (HIF-1α), and p53) mediating the reprogramming of cancer metabolism (including glucose metabolism, lipid metabolism, and amino acid metabolism). Then we comprehensively explore the latest discoveries and possible mechanisms of the anticancer effects of cannabinoids through the regulation of the above-mentioned related signaling pathways, to provide new targets and insights for cancer prevention and treatment.

Cellular signals integrate cell cycle and metabolic control in cancer

Growth factors are the small peptides that can promote growth, differentiation, and survival of most living cells. However, aberrant activation of receptor tyrosine kinases by GFs can generate oncogenic signals, resulting in oncogenic transformation. Accumulating evidence support a link between GF/RTK signaling through the major signaling pathways, Ras/Erk and PI3K/Akt, and cell cycle progression. In response to GF signaling, the quiescent cells in the G₀ stage can re-enter the cell cycle and become the proliferative stage. While in the proliferative stage, tumor cells undergo profound changes in their metabolism to support biomass production and bioenergetic requirements. Accumulating data show that the cell cycle regulators, specifically cyclin D, cyclin B, Cdk2, Cdk4, and Cdk6, and anaphase-promoting complex/cyclosome (APC/C-Cdh1) play critical roles in modulating various metabolic pathways. These cell cycle regulators can regulate metabolic enzyme activities through post-translational mechanisms or the transcriptional factors that control the expression of the metabolic genes. This fine-tune control allows only the relevant metabolic pathways to be active in a particular phase of the cell cycle, thereby providing suitable amounts of biosynthetic precursors available during the proliferative stage. The imbalance of metabolites in each cell cycle phase can induce cell cycle arrest followed by p53-induced apoptosis.

Understanding the Contribution of Lactate Metabolism in Cancer Progress: A Perspective from Isomers

Lactate mediates multiple cell-intrinsic effects in cancer metabolism in terms of development, maintenance, and metastasis and is often correlated with poor prognosis. Its functions are undertaken as an energy source for neighboring carcinoma cells and serve as a lactormone for oncogenic signaling pathways. Indeed, two isomers of lactate are produced in the Warburg effect: L-lactate and D-lactate. L-lactate is the main end-production of glycolytic fermentation which catalyzes glucose, and tiny D-lactate is fabricated through the glyoxalase system. Their production inevitably affects cancer development and therapy. Here, we systematically review the mechanisms of lactate isomers production, and highlight emerging evidence of the carcinogenic biological effects of lactate and its isomers in cancer. Accordingly, therapy that targets lactate and its metabolism is a promising approach for anticancer treatment.

Overview of Cancer Metabolism and Signaling Transduction

Despite the remarkable progress in cancer treatment up to now, we are still far from conquering the disease. The most substantial change after the malignant transformation of normal cells into cancer cells is the alteration in their metabolism. Cancer cells reprogram their metabolism to support the elevated energy demand as well as the acquisition and maintenance of their malignancy, even in nutrient-poor environments. The metabolic alterations, even under aerobic conditions, such as the upregulation of the glucose uptake and glycolysis (the Warburg effect), increase the ROS (reactive oxygen species) and glutamine dependence, which are the prominent features of cancer metabolism. Among these metabolic alterations, high glutamine dependency has attracted serious attention in the cancer research community. In addition, the oncogenic signaling pathways of the well-known important genetic mutations play important regulatory roles, either directly or indirectly, in the central carbon metabolism. The identification of the convergent metabolic phenotypes is crucial to the targeting of cancer cells. In this review, we investigate the relationship between cancer metabolism and the signal transduction pathways, and we highlight the recent developments in anti-cancer therapy that target metabolism.