p53 and metabolism

UBE2C enhances temozolomide resistance by regulating the expression of p53 to induce aerobic glycolysis in glioma

UBE2C is overexpressed in gliomas, and its overexpression has been reported to be correlated with the drug resistance of gliomas to some extent. In this study, we explore the role of UBE2C in regulating temozolomide (TMZ) resistance in glioma and investigate the underlying mechanisms involved. Twenty normal brain tissues and 100 glioma tissues from 50 TMZ-resistant patients and 50 TMZ-sensitive patients are included in this study. TMZ-resistant cell lines are constructed to explore the role of UBE2C in regulating glioma cell viability and TMZ resistance. Our results show that both the mRNA and protein levels of UBE2C are significantly elevated in the brain tissues of glioma patients, especially in those of TMZ-resistant patients. Consistently, UBE2C expression is markedly upregulated in TMZ-resistant cell lines. Overexpression of UBE2C rescues glioma cells from TMZ-mediated apoptosis and enhances cell viability. In contrast, downregulation of UBE2C expression further enhances TMZ function, increases cell apoptosis and decreases cell viability. Mechanistically, UBE2C overexpression decreases p53 expression and enhances aerobic glycolysis level by increasing ATP level, lactate production, and glucose uptake. Downregulation of p53 level abolishes the role of UBE2C downregulation in inhibiting TMZ resistance and aerobic glycolysis in glioma cells. Moreover, an animal assay confirms that downregulation of UBE2C expression further suppresses tumor growth in the context of TMZ treatment. Collectively, this study reveals that downregulation of UBE2C expression enhances the sensitivity of glioma cells to TMZ by regulating the expression of p53 to inhibit aerobic glycolysis.

Halogenated Boroxine K2[B3O3F4OH] Modulates Metabolic Phenotype and Autophagy in Human Bladder Carcinoma 5637 Cell Line

Halogenated boroxine K2[B3O3F4OH] (HB), an inorganic derivative of cyclic anhydride of boronic acid, is patented as a boron-containing compound with potential for the treatment of both benign and malignant skin changes. HB has effectively inhibited the growth of several carcinoma cell lines. Because of the growing interest in autophagy induction as a therapeutic approach in bladder carcinoma (BC), we aimed to assess the effects of HB on metabolic phenotype and autophagy levels in 5637 human bladder carcinoma cells (BC). Cytotoxicity was evaluated using the alamar blue assay, and the degree of autophagy was determined microscopically. Mitochondrial respiration and glycolysis were measured simultaneously. The relative expression of autophagy-related genes BECN1, P62, BCL-2, and DRAM1 was determined by real-time PCR. HB affected cell growth, while starvation significantly increased the level of autophagy in the positive control compared to the basal level of autophagy in the untreated negative control. In HB-treated cultures, the degree of autophagy was higher compared to the basal level, and metabolic phenotypes were altered; both glycolysis and oxidative phosphorylation (OXPHOS) were decreased by HB at 0.2 and 0.4 mg/mL. Gene expression was deregulated towards autophagy induction and expansion. In conclusion, HB disrupted the bioenergetic metabolism and reduced the intracellular survival potential of BC cells. Further molecular studies are needed to confirm these findings and investigate their applicative potential.

Bioinformatic analysis and experimental validation of six cuproptosis-associated genes as a prognostic signature of breast cancer

Background

Breast carcinoma (BRCA) is a life-threatening malignancy in women and shows a poor prognosis. Cuproptosis is a novel mode of cell death but its relationship with BRCA is unclear. This study attempted to develop a cuproptosis-relevant prognostic gene signature for BRCA.

Methods

Cuproptosis-relevant subtypes of BRCA were obtained by consensus clustering. Differential expression analysis was implemented using the 'limma' package. Univariate Cox and multivariate Cox analyses were performed to determine a cuproptosis-relevant prognostic gene signature. The signature was constructed and validated in distinct datasets. Gene set variation analysis (GSVA) and gene set enrichment analysis (GSEA) were also conducted using the prognostic signature to uncover the underlying molecular mechanisms. ESTIMATE and CIBERSORT algorithms were applied to probe the linkage between the gene signature and tumor microenvironment (TME). Immunotherapy responsiveness was assessed using the Tumor Immune Dysfunction and Exclusion (TIDE) web tool. Real-time quantitative PCR (RT-qPCR) was performed to detect the expressions of cuproptosis-relevant prognostic genes in breast cancer cell lines.

Results

Thirty-eight cuproptosis-associated differentially expressed genes (DEGs) in BRCA were mined by consensus clustering and differential expression analysis. Based on univariate Cox and multivariate Cox analyses, six cuproptosis-relevant prognostic genes, namely SAA1, KRT17, VAV3, IGHG1, TFF1, and CLEC3A, were mined to establish a corresponding signature. The signature was validated using external validation sets. GSVA and GSEA showed that multiple cell cycle-linked and immune-related pathways along with biological processes were associated with the signature. The results ESTIMATE and CIBERSORT analyses revealed significantly different TMEs between the two Cusig score subgroups. Finally, RT-qPCR analysis of cell lines further confirmed the expressional trends of SAA1, KRT17, IGHG1, and CLEC3A.

Conclusion

Taken together, we constructed a signature for projecting the overall survival of BRCA patients and our findings authenticated the cuproptosis-relevant prognostic genes, which are expected to provide a basis for developing prognostic molecular biomarkers and an in-depth understanding of the relationship between cuproptosis and BRCA.

Understanding the complexity of p53 in a new era of tumor suppression

p53 was discovered 45 years ago as an SV40 large T antigen binding protein, coded by the most frequently mutated TP53 gene in human cancers. As a transcription factor, p53 is tightly regulated by a rich network of post-translational modifications to execute its diverse functions in tumor suppression. Although early studies established p53-mediated cell-cycle arrest, apoptosis, and senescence as the classic barriers in cancer development, a growing number of new functions of p53 have been discovered and the scope of p53-mediated anti-tumor activity is largely expanded. Here, we review the complexity of different layers of p53 regulation, and the recent advance of the p53 pathway in metabolism, ferroptosis, immunity, and others that contribute to tumor suppression. We also discuss the challenge regarding how to activate p53 function specifically effective in inhibiting tumor growth without harming normal homeostasis for cancer therapy.

Systematic Characterization of p53-Regulated Long Noncoding RNAs across Human Cancers Reveals Remarkable Heterogeneity among Different Tumor Types

The p53 tumor suppressor protein, a sequence-specific DNA binding transcription factor, regulates the expression of a large number of genes, in response to various forms of cellular stress. Although the protein coding target genes of p53 have been well studied, less is known about its role in regulating long noncoding genes and their functional relevance to cancer. Here we report the genome-wide identification of a large set (>1,000) of long noncoding RNAs (lncRNA), which are putative p53 targets in a colon cancer cell line and in human patient datasets from five different common types of cancer. These lncRNAs have not been annotated by other studies of normal unstressed systems. In the colon cancer cell line, a high proportion of these lncRNAs are uniquely induced by different chemotherapeutic agents that activate p53, whereas others are induced by more than one agent tested. Further, subsets of these lncRNAs independently predict overall and disease-free survival of patients across the five different common cancer types. Interestingly, both genetic alterations and patient survival associated with different lncRNAs are unique to each cancer tested, indicating extraordinary tissue-specific variability in the p53 noncoding response. The newly identified noncoding p53 target genes have allowed us to construct a classifier for tumor diagnosis and prognosis.

IMPLICATIONS

Our results not only identify myriad p53-regulated long noncoding (lncRNA), they also reveal marked drug-induced, as well as tissue- and tumor-specific heterogeneity in these putative p53 targets and our findings have enabled the construction of robust classifiers for diagnosis and prognosis.

Metabolic signature and response to glutamine deprivation are independent of p53 status in B cell malignancies

The tumor suppressor p53 has been described to control various aspects of metabolic reprogramming in solid tumors, but in B cell malignancies that role is as yet unknown. We generated pairs of p53 functional and knockout (KO) clones from distinct B cell malignancies (acute lymphoblastic leukemia, chronic lymphocytic leukemia, diffuse large B cell lymphoma, and multiple myeloma). Metabolomics and isotope tracing showed that p53 loss did not drive a common metabolic signature. Instead, cell lines segregated according to cell of origin. Next, we focused on glutamine as a crucial energy source in the B cell tumor microenvironment. In both TP53 wild-type and KO cells, glutamine deprivation induced cell death through the integrated stress response, via CHOP/ATF4. Lastly, combining BH3 mimetic drugs with glutamine starvation emerged as a possibility to target resistant clones. In conclusion, our analyses do not support a common metabolic signature of p53 deficiency in B cell malignancies and suggest therapeutic options for exploration based on glutamine dependency.

Unlocking Mitochondrial Dysfunction-Associated Senescence (MiDAS) with NAD + - a Boolean Model of Mitochondrial Dynamics and Cell Cycle Control

The steady accumulation of senescent cells with aging creates tissue environments that aid cancer evolution. Aging cell states are highly heterogeneous. 'Deep senescent' cells rely on healthy mitochondria to fuel a strong proinflammatory secretome, including cytokines, growth and transforming signals. Yet, the physiological triggers of senescence such as the reactive oxygen species (ROS) can also trigger mitochondrial dysfunction, and sufficient energy deficit to alter their secretome and cause chronic oxidative stress - a state termed Mitochondrial Dysfunction-Associated Senescence (MiDAS). Here, we offer a mechanistic hypothesis for the molecular processes leading to MiDAS, along with testable predictions. To do this we have built a Boolean regulatory network model that qualitatively captures key aspects of mitochondrial dynamics during cell cycle progression (hyper-fusion at the G1/S boundary, fission in mitosis), apoptosis (fission and dysfunction) and glucose starvation (reversible hyper-fusion), as well as MiDAS in response to SIRT3 knockdown or oxidative stress. Our model reaffirms the protective role of NAD + and external pyruvate. We offer testable predictions about the growth factor- and glucose-dependence of MiDAS and its reversibility at different stages of reactive oxygen species (ROS)-induced senescence. Our model provides mechanistic insights into the distinct stages of DNA-damage induced senescence, the relationship between senescence and epithelial-to-mesenchymal transition in cancer and offers a foundation for building multiscale models of tissue aging.

Highlights

Boolean regulatory network model reproduces mitochondrial dynamics during cell cycle progression, apoptosis, and glucose starvation. Model offers a mechanistic explanation for the positive feedback loop that locks in Mitochondrial Dysfunction-Associated Senescence (MiDAS), involving autophagy-resistant, hyperfused, dysfunctional mitochondria. Model reproduces ROS-mediated mitochondrial dysfunction and suggests that MiDAS is part of the early phase of damage-induced senescence. Model predicts that cancer-driving mutations that bypass the G1/S checkpoint generally increase the incidence of MiDAS, except for p53 loss.

Metabolic Roles of HIF1, c-Myc, and p53 in Glioma Cells

The metabolic reprogramming that promotes tumorigenesis in glioblastoma is induced by dynamic alterations in the hypoxic tumor microenvironment, as well as in transcriptional and signaling networks, which result in changes in global genetic expression. The signaling pathways PI3K/AKT/mTOR and RAS/RAF/MEK/ERK stimulate cell metabolism, either directly or indirectly, by modulating the transcriptional factors p53, HIF1, and c-Myc. The overexpression of HIF1 and c-Myc, master regulators of cellular metabolism, is a key contributor to the synthesis of bioenergetic molecules that mediate glioma cell transformation, proliferation, survival, migration, and invasion by modifying the transcription levels of key gene groups involved in metabolism. Meanwhile, the tumor-suppressing protein p53, which negatively regulates HIF1 and c-Myc, is often lost in glioblastoma. Alterations in this triad of transcriptional factors induce a metabolic shift in glioma cells that allows them to adapt and survive changes such as mutations, hypoxia, acidosis, the presence of reactive oxygen species, and nutrient deprivation, by modulating the activity and expression of signaling molecules, enzymes, metabolites, transporters, and regulators involved in glycolysis and glutamine metabolism, the pentose phosphate cycle, the tricarboxylic acid cycle, and oxidative phosphorylation, as well as the synthesis and degradation of fatty acids and nucleic acids. This review summarizes our current knowledge on the role of HIF1, c-Myc, and p53 in the genic regulatory network for metabolism in glioma cells, as well as potential therapeutic inhibitors of these factors.

HOPS/TMUB1 Enhances Apoptosis in TP53 Mutation-Independent Setting in Human Cancers

TP53 mutations are prevalent in various cancers, yet the complexity of apoptotic pathway deregulation suggests the involvement of additional factors. HOPS/TMUB1 is known to extend the half-life of p53 under normal and stress conditions, implying a regulatory function. This study investigates, for the first time, the potential modulatory role of the ubiquitin-like-protein HOPS/TMUB1 in p53-mutants. A comprehensive analysis of apoptosis in the most frequent p53-mutants, R175, R248, and R273, in SKBR3, MIA PaCa2, and H1975 cells indicates that the overexpression of HOPS induces apoptosis at least equivalent to that caused by DNA damage. Immunoprecipitation assays confirm HOPS binding to p53-mutant forms. The interaction of HOPS/TMUB1 with p53-mutants strengthens its effect on the apoptotic cascade, showing a context-dependent gain or loss of function. Gene expression analysis of the MYC and TP63 genes shows that H1975 exhibit a gain-of-function profile, while SKBR3 promote apoptosis in a TP63-dependent manner. The TCGA data further corroborate HOPS/TMUB1's positive correlation with apoptotic genes BAX, BBC3, and NOXA1, underscoring its relevance in patient samples. Notably, singular TP53 mutations inadequately explain pathway dysregulation, emphasizing the need to explore additional contributing factors. These findings illuminate the intricate interplay among TP53 mutations, HOPS/TMUB1, and apoptotic pathways, providing valuable insights for targeted cancer interventions.

The immunometabolic function of VGLL3 and female-biased autoimmunity

Autoimmune diseases exhibit a pronounced yet unexplained prevalence among women. Vestigial-like family member 3 (VGLL3), a female-biased factor that promotes autoimmunity, has recently been discovered to assist cells in sensing and adapting to nutritional stress. This role of VGLL3 may confer a selective advantage during the evolution of placental mammals. However, the excessive activation of the VGLL3-mediated energy-sensing pathway can trigger inflammatory cell death and the exposure of self-antigens, leading to the onset of autoimmunity. These observations have raised the intriguing perspective that nutrient sensing serves as a double-edged sword in immune regulation. Mechanistically, VGLL3 intersects with Hippo signaling and activates multiple downstream, immune-associated genes that play roles in metabolic regulation. Understanding the multifaceted roles of VGLL3 in nutrient sensing and immune modulation provides insight into the fundamental question of sexual dimorphism in immunometabolism and sheds light on potential therapeutic targets for autoimmune diseases.

Nanoreceptors promote mutant p53 protein degradation by mimicking selective autophagy receptors

In some cancers mutant p53 promotes the occurrence, development, metastasis and drug resistance of tumours, with targeted protein degradation seen as an effective therapeutic strategy. However, a lack of specific autophagy receptors limits this. Here, we propose the synthesis of biomimetic nanoreceptors (NRs) that mimic selective autophagy receptors. The NRs have both a component for targeting the desired protein, mutant-p53-binding peptide, and a component for enhancing degradation, cationic lipid. The peptide can bind to mutant p53 while the cationic lipid simultaneously targets autophagosomes and elevates the levels of autophagosome formation, increasing mutant p53 degradation. The NRs are demonstrated in vitro and in a patient-derived xenograft ovarian cancer model in vivo. The work highlights a possible direction for treating diseases by protein degradation.

Neuronal IL-17 controls Caenorhabditis elegans developmental diapause through CEP-1/p53

During metazoan development, how cell division and metabolic programs are coordinated with nutrient availability remains unclear. Here, we show that nutrient availability signaled by the neuronal cytokine, ILC-17.1, switches Caenorhabditis elegans development between reproductive growth and dormancy by controlling the activity of the tumor suppressor p53 ortholog, CEP-1. Specifically, upon food availability, ILC-17.1 signaling by amphid neurons promotes glucose utilization and suppresses CEP-1/p53 to allow growth. In the absence of ILC-17.1, CEP-1/p53 is activated, up-regulates cell-cycle inhibitors, decreases phosphofructokinase and cytochrome C expression, and causes larvae to arrest as stress-resistant, quiescent dauers. We propose a model whereby ILC-17.1 signaling links nutrient availability and energy metabolism to cell cycle progression through CEP-1/p53. These studies describe ancestral functions of IL-17 s and the p53 family of proteins and are relevant to our understanding of neuroimmune mechanisms in cancer. They also reveal a DNA damage-independent function of CEP-1/p53 in invertebrate development and support the existence of a previously undescribed C. elegans dauer pathway.

Targeting the Warburg effect: A revisited perspective from molecular mechanisms to traditional and innovative therapeutic strategies in cancer

Cancer reprogramming is an important facilitator of cancer development and survival, with tumor cells exhibiting a preference for aerobic glycolysis beyond oxidative phosphorylation, even under sufficient oxygen supply condition. This metabolic alteration, known as the Warburg effect, serves as a significant indicator of malignant tumor transformation. The Warburg effect primarily impacts cancer occurrence by influencing the aerobic glycolysis pathway in cancer cells. Key enzymes involved in this process include glucose transporters (GLUTs), HKs, PFKs, LDHs, and PKM2. Moreover, the expression of transcriptional regulatory factors and proteins, such as FOXM1, p53, NF-κB, HIF1α, and c-Myc, can also influence cancer progression. Furthermore, lncRNAs, miRNAs, and circular RNAs play a vital role in directly regulating the Warburg effect. Additionally, gene mutations, tumor microenvironment remodeling, and immune system interactions are closely associated with the Warburg effect. Notably, the development of drugs targeting the Warburg effect has exhibited promising potential in tumor treatment. This comprehensive review presents novel directions and approaches for the early diagnosis and treatment of cancer patients by conducting in-depth research and summarizing the bright prospects of targeting the Warburg effect in cancer.

Metabolic symbiosis between oxygenated and hypoxic tumour cells: An agent-based modelling study

Deregulated metabolism is one of the hallmarks of cancer. It is well-known that tumour cells tend to metabolize glucose via glycolysis even when oxygen is available and mitochondrial respiration is functional. However, the lower energy efficiency of aerobic glycolysis with respect to mitochondrial respiration makes this behaviour, namely the Warburg effect, counter-intuitive, although it has now been recognized as source of anabolic precursors. On the other hand, there is evidence that oxygenated tumour cells could be fuelled by exogenous lactate produced from glycolysis. We employed a multi-scale approach that integrates multi-agent modelling, diffusion-reaction, stoichiometric equations, and Boolean networks to study metabolic cooperation between hypoxic and oxygenated cells exposed to varying oxygen, nutrient, and inhibitor concentrations. The results show that the cooperation reduces the depletion of environmental glucose, resulting in an overall advantage of using aerobic glycolysis. In addition, the oxygen level was found to be decreased by symbiosis, promoting a further shift towards anaerobic glycolysis. However, the oxygenated and hypoxic populations may gradually reach quasi-equilibrium. A sensitivity analysis using Latin hypercube sampling and partial rank correlation shows that the symbiotic dynamics depends on properties of the specific cell such as the minimum glucose level needed for glycolysis. Our results suggest that strategies that block glucose transporters may be more effective to reduce tumour growth than those blocking lactate intake transporters.

AMPK/PGC-1α and p53 modulate VDAC1 expression mediated by reduced ATP level and metabolic oxidative stress in neuronal cells

Voltage-dependent anion channel 1 (VDAC1) is a pore protein located in the outer mitochondrial membrane. Its channel gating mediates mitochondrial respiration and cell metabolism, and it has been identified as a critical modulator of mitochondria-mediated apoptosis. In many diseases characterized by mitochondrial dysfunction, such as cancer and neurodegenerative diseases, VDAC1 is considered a promising potential therapeutic target. However, there is limited research on the regulatory factors involved in VDAC1 protein expression in both normal and pathological states. In this study, we find that VDAC1 protein expression is up-regulated in various neuronal cell lines in response to intracellular metabolic and oxidative stress. We further demonstrate that VDAC1 expression is modulated by intracellular ATP level. Through the use of pharmacological agonists and inhibitors and small interfering RNA (siRNA), we reveal that the AMPK/PGC-1α signaling pathway is involved in regulating VDAC1 expression. Additionally, based on bioinformatics predictions and biochemical verification, we identify p53 as a potential transcription factor that regulates VDAC1 promoter activity during metabolic oxidative stress. Our findings suggest that VDAC1 expression is regulated by the AMPK/PGC-1α and p53 pathways, which contributes to the maintenance of stress adaptation and apoptotic homeostasis in neuronal cells.

The dynamic relationship between inorganic polyphosphate and adenosine triphosphate in human non-small cell lung cancer H1299 cells

Inorganic polyphosphate (polyP) plays a vital role in cellular energy metabolism and signaling, owing to its structure and high-energy phosphate bonds. Intracellular ATP functions both as a cellular energy source and a key factor in cell death, and ATP dynamics in tumor cells are crucial for advancing cancer therapy. In this study, we explored the interplay between polyP and ATP in cellular energy metabolism. Treatment with polyP did not affect cell proliferation of human non-small cell lung cancer H1299 and human glioblastoma T98G cell lines as compared to their respective control cells until 72 h post-treatment. The mitochondrial membrane potential (MMP) in polyP-treated cells was low, contrasting with the time-dependent increase observed in control cells. While the ATP content increased over time in untreated and Na-phosphate-treated control cells, it remained unchanged in polyP-treated cells. Furthermore, the addition of cyclosporine A, a mitochondrial permeability transition pore (mPTP) inhibitor, failed to restore ATP levels in polyP-treated cells. We performed lactate assays and western blot analysis to evaluate the effect of polyP on glucose metabolism and found no significant differences in lactate secretion or glucose-6-phosphate dehydrogenase (G6PD) activity between polyP-treated and control cells. Additional pyruvate restored MMP but had no effect on the cellular ATP content in polyP-treated cells. We observed no correlation between the Warburg effect and glucose metabolism during ATP depletion in polyP-treated cells. Further investigation is warranted to explore the roles of polyP and ATP in cancer cell energy metabolism, which might offer potential avenues for therapeutic interventions.

HSPA12A acts as a scaffolding protein to inhibit cardiac fibroblast activation and cardiac fibrosis

INTRODUCTION

Cardiac fibrosis is the main driver for adverse remodeling and progressive functional decline in nearly all types of heart disease including myocardial infarction (MI). The activation of cardiac fibroblasts (CF) into myofibroblasts is responsible for cardiac fibrosis. Unfortunately, no ideal approach for controlling CF activation currently exists.

OBJECTIVES

This study investigated the role of Heat shock protein A12A (HSPA12A), an atypical member of the HSP70 family, in CF activation and MI-induced cardiac fibrosis.

METHODS

Primary CF and Hspa12a knockout mice were used in the experiments. CF activation was indicated by the upregulation of myofibroblast characters including alpha-Smooth muscle actin (αSMA), Collagen, and Fibronectin. Cardiac fibrosis was illustrated by Masson's trichrome and picrosirius staining. Cardiac function was examined using echocardiography. Glycolytic activity was indicated by levels of extracellular lactate and the related protein expression. Protein stability was examined following cycloheximide and MG132 treatment. Protein-protein interaction was examined by immunoprecipitation-immunoblotting analysis.

RESULTS

HSPA12A displayed a high expression level in quiescent CF but showed a decreased expression in activated CF, while ablation of HSPA12A in mice promoted CF activation and cardiac fibrosis following MI. HSPA12A overexpression inhibited the activation of primary CF through inhibiting glycolysis, while HSPA12A knockdown showed the opposite effects. Moreover, HSPA12A upregulated the protein expression of transcription factor p53, by which mediated the HSPA12A-induced inhibition of glycolysis and CF activation. Mechanistically, this action of HSPA12A was achieved by acting as a scaffolding protein to bind p53 and ubiquitin specific protease 10 (USP10), thereby promoting the USP10-mediated p53 protein stability and the p53-medicated glycolysis inhibition.

CONCLUSION

The present study provided clear evidence that HSPA12A is a novel endogenous inhibitor of CF activation and cardiac fibrosis. Targeting HSPA12A in CF could represent a promising strategy for the management of cardiac fibrosis in patients.

Unveiling OSCP as the potential therapeutic target for mitochondrial dysfunction-related diseases

Mitochondria are important organelles in cells responsible for energy production and regulation. Mitochondrial dysfunction has been implicated in the pathogenesis of many diseases. Oligomycin sensitivity-conferring protein (OSCP), a component of the inner mitochondrial membrane, has been studied for a long time. OSCP is a component of the F1Fo-ATP synthase in mitochondria and is closely related to the regulation of the mitochondrial permeability transition pore (mPTP). Studies have shown that OSCP plays an important role in cardiovascular disease, neurological disorders, and tumor development. This review summarizes the localization, structure, function, and regulatory mechanisms of OSCP and outlines its role in cardiovascular disease, neurological disease, and tumor development. In addition, this article reviews the research on the interaction between OSCP and mPTP. Finally, the article suggests future research directions, including further exploration of the mechanism of action of OSCP, the interaction between OSCP and other proteins and signaling pathways, and the development of new treatment strategies for mitochondrial dysfunction. In conclusion, in-depth research on OSCP will help to elucidate its importance in cell function and disease and provide new ideas for the treatment and prevention of related diseases.

Doxorubicin Attenuates Free Fatty Acid-Induced Lipid Accumulation via Stimulation of p53 in HepG2 Cells

Non-alcoholic fatty liver disease (NAFLD) is characterized by excessive accumulation of fat in the liver, and there is a global increase in its incidence owing to changes in lifestyle and diet. Recent findings suggest that p53 is involved in the development of non-alcoholic fatty liver disease; however, the association between p53 expression and the disease remains unclear. Doxorubicin, an anticancer agent, increases the expression of p53. Therefore, this study aimed to investigate the role of doxorubicin-induced p53 upregulation in free fatty acid (FFA)-induced intracellular lipid accumulation. HepG2 cells were pretreated with 0.5 μg/mL of doxorubicin for 12 h, followed by treatment with FFA (0.5 mM) for 24 h to induce steatosis. Doxorubicin pretreatment upregulated p53 expression and downregulated the expression of endoplasmic reticulum stress- and lipid synthesis-associated genes in the FFA -treated HepG2 cells. Additionally, doxorubicin treatment upregulated the expression of AMP-activated protein kinase, a key modulator of lipid metabolism. Notably, siRNA-targeted p53 knockdown reversed the effects of doxorubicin in HepG2 cells. Moreover, doxorubicin treatment suppressed FFA -induced lipid accumulation in HepG2 spheroids. Conclusively, these results suggest that doxorubicin possesses potential application for the regulation of lipid metabolism by enhance the expression of p53 an in vitro NAFLD model.

A cytosolic mutp53(E285K) variant confers chemoresistance of malignant melanoma

Malignant melanoma (MM) is known to be intrinsically chemoresistant, even though only ~20% of MM carry mutations of the tumor suppressor p53. Despite improvement of systemic therapy the mortality rate of patients suffering from metastatic MM is still ~70%, highlighting the need for alternative treatment options or for the re-establishment of conventional therapeutic approaches, including chemotherapy. Screening the p53 mutation status in a cohort of 19 patient-derived melanoma samples, we identified one rarely described missense mutation of p53 leading to E285K amino acid exchange (mutp53(E285K)). Employing structural and computational analysis we revealed a major role of E285 residue in maintaining stable conformation of wild-type p53 (wtp53). E285K mutation was predicted to cause interruption of a salt-bridge network affecting the conformation of the C-terminal helix of the DNA-binding domain (DBD) thereby preventing DNA interaction. In this context, a cluster of frequently mutated amino acid residues in cancer was identified to putatively lead to similar structural effects as E285K substitution (E285 cluster). Functional analysis, including knockdown of endogenous p53 and reconstitution with diverse p53 missense mutants confirmed mutp53(E285K) to have lost transcriptional activity, to be localized in the cytosol of cancer cells, by both means conferring chemoresistance. Re-sensitization to cisplatin-induced cell death was achieved using clinically approved compounds aiming to restore p53 wild-type function (PRIMA1-Met), or inhibition of AKT-driven MAPK survival pathways (afuresertib), in both cases being partially due to ferroptosis induction. Consequently, active ferroptosis induction using the GPX4 inhibitor RSL3 proved superior in tumorselectively fighting MM cells. Due to high prevalence of the E285-cluster mutations in MM as well as in a variety of other tumor types, we conclude this cluster to serve an important function in tumor development and therapy and suggest new implications for ferroptosis induction in therapeutic applications fighting MM in particular and cancer in general.

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.

Uridine-cytidine kinase 2 potentiates the mutagenic influence of the antiviral β-d-N4-hydroxycytidine

Molnupiravir (EIDD-2801) is an antiviral that received approval for the treatment of severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) infection. Treatment of bacteria or cell lines with the active form of molnupiravir, β-d-N4-hydroxycytidine (NHC, or EIDD-1931), induces mutations in DNA. Yet these results contrast in vivo genotoxicity studies conducted during registration of the drug. Using a CRISPR screen, we found that inactivating the pyrimidine salvage pathway component uridine-cytidine kinase 2 (Uck2) renders cells more tolerant of NHC. Short-term exposure to NHC increased the mutation rate in a mouse myeloid cell line, with most mutations being T:A to C:G transitions. Inactivating Uck2 impaired the mutagenic activity of NHC, whereas over-expression of Uck2 enhanced mutagenesis. UCK2 is upregulated in many cancers and cell lines. Our results suggest differences in ribonucleoside metabolism contribute to the variable mutagenicity of NHC observed in cancer cell lines and primary tissues.

Emerging role and therapeutic implications of p53 in intervertebral disc degeneration

Lower back pain (LBP) is a common degenerative musculoskeletal disease that imposes a huge economic burden on both individuals and society. With the aggravation of social aging, the incidence of LBP has increased globally. Intervertebral disc degeneration (IDD) is the primary cause of LBP. Currently, IDD treatment strategies include physiotherapy, medication, and surgery; however, none can address the root cause by ending the degeneration of intervertebral discs (IVDs). However, in recent years, targeted therapy based on specific molecules has brought hope for treating IDD. The tumor suppressor gene p53 produces a transcription factor that regulates cell metabolism and survival. Recently, p53 was shown to play an important role in maintaining IVD microenvironment homeostasis by regulating IVD cell senescence, apoptosis, and metabolism by activating downstream target genes. This study reviews research progress regarding the potential role of p53 in IDD and discusses the challenges of targeting p53 in the treatment of IDD. This review will help to elucidate the pathogenesis of IDD and provide insights for the future development of precision treatments.

Mutant p53 gain-of-function stimulates canonical Wnt signaling via PI3K/AKT pathway in colon cancer

Aberrant canonical Wnt signaling is a hallmark of colon cancer. The TP53 tumor suppressor gene is altered in many solid tumors, including colorectal cancer, resulting in mutant versions of p53 (mut-p53) that lose their tumor suppressor capacities and acquire new-oncogenic functions (GOFs) critical for disease progression. Although the mechanisms related to mut-p53 GOF have been explored extensively, the relevance of mut-p53 in the canonical Wnt pathway is not well defined. This work investigated the influence of mut-p53 compared to wt-p53 in β-catenin-dependent Wnt signaling. Using the TCGA public data from Pan-Cancer and the GEPIA2 platform, an in silico analysis of wt-p53 versus mut-p53 genotyped colorectal cancer patients showed that TP53 (p53) and CTNNB1 (β-catenin) are significantly overexpressed in colorectal cancer, compared with normal tissue. Using p53 overexpression or p53 knockdown assays of wt-p53 or mut-p53, we found that while wt-p53 antagonizes canonical Wnt signaling, mut-p53 induces the opposite effect, improving the β-catenin-dependent transcriptional activity and colony formation ability of colon cancer cells, which were both decreased by mut-p53 knockdown expression. The mechanism involved in mut-p53-induced activation of canonical Wnt appears to be via AKT-mediated phosphorylation of Ser 552 of β-catenin, which is known to stabilize and enhance its transcriptional activity. We also found that while wt-p53 expression contributes to 5-FU sensitivity in colon cancer cells, the RITA p53 reactivating molecule counteracted the resistance against 5-FU in cells expressing mut-p53. Our results indicate that mut-p53 GOF acts as a positive regulator of canonical Wnt signaling and participates in the induction of resistance to 5-FU in colon cancer cells.

Acne Transcriptomics: Fundamentals of Acne Pathogenesis and Isotretinoin Treatment

This review on acne transcriptomics allows for deeper insights into the pathogenesis of acne and isotretinoin's mode of action. Puberty-induced insulin-like growth factor 1 (IGF-1), insulin and androgen signaling activate the kinase AKT and mechanistic target of rapamycin complex 1 (mTORC1). A Western diet (hyperglycemic carbohydrates and milk/dairy products) also co-stimulates AKT/mTORC1 signaling. The AKT-mediated phosphorylation of nuclear FoxO1 and FoxO3 results in their extrusion into the cytoplasm, a critical switch which enhances the transactivation of lipogenic and proinflammatory transcription factors, including androgen receptor (AR), sterol regulatory element-binding transcription factor 1 (SREBF1), peroxisome proliferator-activated receptor γ (PPARγ) and signal transducer and activator of transcription 3 (STAT3), but reduces the FoxO1-dependent expression of GATA binding protein 6 (GATA6), the key transcription factor for infundibular keratinocyte homeostasis. The AKT-mediated phosphorylation of the p53-binding protein MDM2 promotes the degradation of p53. In contrast, isotretinoin enhances the expression of p53, FoxO1 and FoxO3 in the sebaceous glands of acne patients. The overexpression of these proapoptotic transcription factors explains isotretinoin's desirable sebum-suppressive effect via the induction of sebocyte apoptosis and the depletion of BLIMP1(+) sebocyte progenitor cells; it also explains its adverse effects, including teratogenicity (neural crest cell apoptosis), a reduced ovarian reserve (granulosa cell apoptosis), the risk of depression (the apoptosis of hypothalamic neurons), VLDL hyperlipidemia, intracranial hypertension and dry skin.

p63 orchestrates serine and one carbon metabolism enzymes expression in head and neck cancer

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is characterized by high proliferation and limited differentiation. The altered expression of the p53 family members, and specifically of p63, represents a pivotal event in the pathogenesis of HNSCC. Physiologically, p63 affects metabolism through the direct transactivation of the enzyme hexokinase 2, and subsequently controls the proliferation of epithelial cells; nonetheless, its role in cancer metabolism is still largely unclear. The high energetic demand of cancer and the consequent needs of a metabolic reshape, also involve the serine and glycine catabolic and anabolic pathways, including the one carbon metabolism (OCM), to produce energetic compounds (purines) and to maintain cellular homeostasis (glutathione and S-adenosylmethionine).

RESULTS

The involvement in serine/glycine starvation by other p53 family members has been reported, including HNSCC. Here, we show that in HNSCC p63 controls the expression of the enzymes regulating the serine biosynthesis and one carbon metabolism. p63 binds the promoter region of genes involved in the serine biosynthesis as well as in the one carbon metabolism. p63 silencing in a HNSCC cell line affects the mRNA and protein levels of these selected enzymes. Moreover, the higher expression of TP63 and its target enzymes, negatively impacts on the overall survival of HNSCC patients.

CONCLUSION

These data indicate a direct role of p63 in the metabolic regulation of HNSCC with significant clinical effects.

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.

Metabolic interventions combined with CTLA-4 and PD-1/PD-L1 blockade for the treatment of tumors: mechanisms and strategies

Immunotherapies based on immune checkpoint blockade (ICB) have significantly improved patient outcomes and offered new approaches to cancer therapy over the past decade. To date, immune checkpoint inhibitors (ICIs) of CTLA-4 and PD-1/PD-L1 represent the main class of immunotherapy. Blockade of CTLA-4 and PD-1/PD-L1 has shown remarkable efficacy in several specific types of cancers, however, a large subset of refractory patients presents poor responsiveness to ICB therapy; and the underlying mechanism remains elusive. Recently, numerous studies have revealed that metabolic reprogramming of tumor cells restrains immune responses by remodeling the tumor microenvironment (TME) with various products of metabolism, and combination therapies involving metabolic inhibitors and ICIs provide new approaches to cancer therapy. Nevertheless, a systematic summary is lacking regarding the manner by which different targetable metabolic pathways regulate immune checkpoints to overcome ICI resistance. Here, we demonstrate the generalized mechanism of targeting cancer metabolism at three crucial immune checkpoints (CTLA-4, PD-1, and PD-L1) to influence ICB therapy and propose potential combined immunotherapeutic strategies co-targeting tumor metabolic pathways and immune checkpoints.

Recent advances in targeting the "undruggable" proteins: from drug discovery to clinical trials

Undruggable proteins are a class of proteins that are often characterized by large, complex structures or functions that are difficult to interfere with using conventional drug design strategies. Targeting such undruggable targets has been considered also a great opportunity for treatment of human diseases and has attracted substantial efforts in the field of medicine. Therefore, in this review, we focus on the recent development of drug discovery targeting "undruggable" proteins and their application in clinic. To make this review well organized, we discuss the design strategies targeting the undruggable proteins, including covalent regulation, allosteric inhibition, protein-protein/DNA interaction inhibition, targeted proteins regulation, nucleic acid-based approach, immunotherapy and others.

Role of Human Monocarboxylate Transporter 1 (hMCT1) and 4 (hMCT4) in Tumor Cells and the Tumor Microenvironment

In recent years, the abnormal glucose metabolism of tumor cells has attracted increasing attention. Abnormal glucose metabolism is closely related to the occurrence and development of tumors. Monocarboxylate transporters (MCTs) transport the sugar metabolites lactic acid and pyruvate, which affect glucose metabolism and tumor progression in a variety of ways. Thus, research has recently focused on MCTs and their potential functions in cancer. The MCT superfamily consists of 14 members. MCT1 and MCT4 play a crucial role in the maintenance of intracellular pH in tumor cells by transporting monocarboxylic acids (such as lactate, pyruvate and butyrate). MCT1 and MCT4 are highly expressed in a variety of tumor cells and are involved the proliferation, invasion and migration of tumor cells, which are closely related to the prognosis of cancer. Because of their important functions in tumor cells, MCT1 and MCT4 have become potential targets for cancer treatment. In this review, we focus on the structure, function and regulation of MCT1 and MCT4 and discuss the developed inhibitors of MCT1 and MCT4 to provide more comprehensive information that might aid in the development of strategies targeting MCTs in cancer.

The African-centric P47S Variant of TP53 Confers Immune Dysregulation and Impaired Response to Immune Checkpoint Inhibition

The tumor suppressor TP53 is the most frequently mutated gene in cancer and is mutationally inactivated in 50% of sporadic tumors. Inactivating mutations in TP53 also occur in Li Fraumeni syndrome (LFS). In addition to germline mutations in TP53 in LFS that completely inactivate this protein, there are many more germline mutant forms of TP53 in human populations that partially inactivate this protein: we call these partially inactivating mutations "hypomorphs." One of these hypomorphs is a SNP that exists in 6%-10% of Africans and 1%-2% of African Americans, which changes proline at amino acid 47 to serine (Pro47Ser; P47S). We previously showed that the P47S variant of p53 is intrinsically impaired for tumor suppressor function, and that this SNP is associated with increased cancer risk in mice and humans. Here we show that this SNP also influences the tumor microenvironment, and the immune microenvironment profile in P47S mice is more protumorigenic. At basal levels, P47S mice show impaired memory T-cell formation and function, along with increased anti-inflammatory (so-called "M2") macrophages. We show that in tumor-bearing P47S mice, there is an increase in immunosuppressive myeloid-derived suppressor cells and decreased numbers of activated dendritic cells, macrophages, and B cells, along with evidence for increased T-cell exhaustion in the tumor microenvironment. Finally, we show that P47S mice demonstrate an incomplete response to anti-PD-L1 therapy. Our combined data suggest that the African-centric P47S variant leads to both intrinsic and extrinsic defects in tumor suppression.

Significance

Findings presented here show that the P47S variant of TP53 influences the immune microenvironment, and the immune response to cancer. This is the first time that a naturally occurring genetic variant of TP53 has been shown to negatively impact the immune microenvironment and the response to immunotherapy.

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.

Cysteine depletion sensitizes prostate cancer cells to agents that enhance DNA damage and to immune checkpoint inhibition

BACKGROUND

Prostate Cancer (PCa) represents one of the most commonly diagnosed neoplasms in men and is associated with significant morbidity and mortality. Therapy resistance and significant side effects of current treatment strategies indicate the need for more effective agents to treat both androgen-dependent and androgen-independent PCa. In earlier studies, we demonstrated that depletion of L-cysteine/cystine with an engineered human enzyme, Cyst(e)inase, increased intracellular ROS levels and inhibited PCa growth in vitro and in vivo. The current study was conducted to further explore the mechanisms and potential combinatorial approaches with Cyst(e)inase for treatment of PCa.

METHODS

DNA single strand breaks and clustered oxidative DNA damage were evaluated by alkaline comet assay and pulsed field gel electrophoresis, respectively. Neutral comet assay and immunofluorescence staining was used to measure DNA double strand breaks. Cell survival and reactive oxygen species level were measured by crystal violet assay and DCFDA staining, respectively. Western blot was used to determine protein expression. FACS analyses were preformed for immune cell phenotyping. Allograft and xenograft tumor models were used for assessing effects on tumor growth.

RESULTS

PCa cells treated with Cyst(e)inase lead to DNA single and double strand breaks resulted from clustered oxidative DNA damage (SSBs and DSBs). Cyst(e)inase in combination with Auranofin, a thioredoxin reductase inhibitor, further increased intracellular ROS and DNA DSBs and synergistically inhibited PCa cell growth in vitro and in vivo. A combination of Cyst(e)inase with a PARP inhibitor (Olaparib) also increased DNA DSBs and synergistically inhibited PCa cell growth in vitro and in vivo without additional ROS induction. Knockdown of BRCA2 in PCa cells increased DSBs and enhanced sensitivity to Cyst(e)inase. Finally, Cyst(e)inase treatment altered tumor immune infiltrates and PD-L1 expression and sensitized PCa cells to anti-PD-L1 treatment.

CONCLUSIONS

The current results demonstrate the importance of oxidative DNA damage either alone or in combination for Cyst(e)inase-induced anticancer activity. Furthermore, cysteine/cystine depletion alters the tumor immune landscape favoring enhanced immune checkpoint inhibition targeting PD-L1. Thus, combinatorial approaches with Cyst(e)inase could lead to novel therapeutic strategies for PCa.

Prognosis-related metabolic genes in the development of colorectal cancer progress and perspective

Colorectal cancer (CRC) is one of the most commonplace malignant tumors in the world. The occurrence and development of CRC are involved in numerous events. Metabolic reprogramming is one of the hallmarks of cancer and is convoluted and associated with carcinogenesis. Lots of metabolic genes are involved in the occurrence and progression of CRC. Study methods combining tumor genomics and metabolomics are more likely to explore this field in depth. In this mini-review, we make the latest progress and future prospects into the different molecular mechanisms of seven prognosis-related metabolic genes, we screened out in previous research, involved in the occurrence and development of CRC.

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.

The spectrum of cell death in sarcoma

The balance between cell death and cell survival is a highly coordinated process by which cells break down and remove unnecessary or harmful materials in a controlled, highly regulated, and compartmentalized manner. Cell exposure to various stresses, such as oxygen starvation, a lack of nutrients, or exposure to radiation, can initiate autophagy. Autophagy is a carefully orchestrated process with multiple steps, each regulated by specific genes and proteins. Autophagy proteins impact cellular maintenance and cell fate in response to stress, and targeting this process is one of the most promising methods of anti-tumor therapy. It is currently not fully understood how autophagy affects different types of tumor cells, which makes it challenging to predict outcomes when this process is manipulated. In this review, we will explore the mechanisms of autophagy and investigate it as a potential and promising therapeutic target for aggressive sarcomas.

Tissue specificity and spatio-temporal dynamics of the p53 transcriptional program

Transcription factors regulate hundreds of genes and p53 is no exception. As a stress responsive protein, p53 transactivates an array of downstream targets which define its role in maintaining physiological functions of cells/tissues. Despite decades of studies, our understanding of the p53 in vivo transcriptional program is still incomplete. Here we discuss some of the physiological stressors that activate p53, the pathological and physiological implications of p53 activation and the molecular profiling of the p53 transcriptional program in maintaining tissue homeostasis. We argue that the p53 transcriptional program is spatiotemporally regulated in a tissue-specific manner and define a p53 target signature that faithfully depicts p53 activity. We further emphasize that additional in vivo studies are needed to refine the p53 transactivation profile to harness it for therapeutic purposes.

Targeting the Molecular and Immunologic Features of Leiomyosarcoma

Leiomyosarcoma (LMS) is a rare, aggressive mesenchymal tumor with smooth muscle differentiation. LMS is one of the most common histologic subtypes of soft tissue sarcoma; it most frequently occurs in the extremities, retroperitoneum, or uterus. LMS often demonstrates aggressive tumor biology, with a higher risk of developing distant metastatic disease than most sarcoma histologic types. The prognosis is poor, particularly in patients with uterine disease, and there is a need for the development of more effective therapies. Genetically, LMS is karyotypically complex and characterized by a low tumor mutational burden, with frequent alterations in TP53, RB1, PTEN, and DNA damage response pathways that may contribute to resistance against immune-checkpoint blockade monotherapy. The LMS immune microenvironment is highly infiltrated with tumor-associated macrophages and tumor-infiltrating lymphocytes, which may represent promising biomarkers. This review provides an overview of the clinical and pathologic behavior of both soft tissue and uterine LMS and summarizes the genomic and immune characteristics of these tumors and how they may provide opportunities for the development of biomarker-based immune therapies.

Targeting Mitochondria with ClpP Agonists as a Novel Therapeutic Opportunity in Breast Cancer

Breast cancer is the most frequently diagnosed malignancy worldwide and the leading cause of cancer mortality in women. Despite the recent development of new therapeutics including targeted therapies and immunotherapy, triple-negative breast cancer remains an aggressive form of breast cancer, and thus improved treatments are needed. In recent decades, it has become increasingly clear that breast cancers harbor metabolic plasticity that is controlled by mitochondria. A myriad of studies provide evidence that mitochondria are essential to breast cancer progression. Mitochondria in breast cancers are widely reprogrammed to enhance energy production and biosynthesis of macromolecules required for tumor growth. In this review, we will discuss the current understanding of mitochondrial roles in breast cancers and elucidate why mitochondria are a rational therapeutic target. We will then outline the status of the use of mitochondria-targeting drugs in breast cancers, and highlight ClpP agonists as emerging mitochondria-targeting drugs with a unique mechanism of action. We also illustrate possible drug combination strategies and challenges in the future breast cancer clinic.

METTL14 modulates glycolysis to inhibit colorectal tumorigenesis in p53-wild-type cells

The frequency of p53 mutations in colorectal cancer (CRC) is approximately 40-50%. A variety of therapies are being developed to target tumors expressing mutant p53. However, potential therapeutic targets for CRC expressing wild-type p53 are rare. In this study, we show that METTL14 is transcriptionally activated by wild-type p53 and suppresses tumor growth only in p53-wild-type (p53-WT) CRC cells. METTL14 deletion promotes both AOM/DSS and AOM-induced CRC growth in mouse models with the intestinal epithelial cell-specific knockout of METTL14. Additionally, METTL14 restrains aerobic glycolysis in p53-WT CRC, by repressing SLC2A3 and PGAM1 expression via selectively promoting m⁶ A-YTHDF2-dependent pri-miR-6769b/pri-miR-499a processing. Biosynthetic mature miR-6769b-3p and miR-499a-3p decrease SLC2A3 and PGAM1 levels, respectively, and suppress malignant phenotypes. Clinically, METTL14 only acts as a beneficial prognosis factor for the overall survival of p53-WT CRC patients. These results uncover a new mechanism for METTL14 inactivation in tumors and, most importantly, reveal that the activation of METTL14 is a critical mechanism for p53-dependent cancer growth inhibition, which could be targeted for therapy in p53-WT CRC.

Mutant P53 in the formation and progression of the tumor microenvironment: Friend or foe

TP53 is the most frequently mutated gene in human cancer. It encodes the tumor suppressor protein p53, which suppresses tumorigenesis by acting as a critical transcription factor that can induce the expression of many genes controlling a plethora of fundamental cellular processes, including cell cycle progression, survival, apoptosis, and DNA repair. Missense mutations are the most frequent type of mutations in the TP53 gene. While these can have variable effects, they typically impair p53 function in a dominant-negative manner, thereby altering intra-cellular signaling pathways and promoting cancer development. Additionally, it is becoming increasingly apparent that p53 mutations also have non-cell autonomous effects that influence the tumor microenvironment (TME). The TME is a complex and heterogeneous milieu composed of both malignant and non-malignant cells, including cancer-associated fibroblasts (CAFs), adipocytes, pericytes, different immune cell types, such as tumor-associated macrophages (TAMs) and T and B lymphocytes, as well as lymphatic and blood vessels and extracellular matrix (ECM). Recently, a large body of evidence has demonstrated that various types of p53 mutations directly affect TME. They fine-tune the inflammatory TME and cell fate reprogramming, which affect cancer progression. Notably, re-educating the p53 signaling pathway in the TME may be an effective therapeutic strategy in combating cancer. Therefore, it is timely to here review the recent advances in our understanding of how TP53 mutations impact the fate of cancer cells by reshaping the TME.

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.

Metabolic reprogramming of glutamine involved in tumorigenesis, multidrug resistance and tumor immunity

Glutamine, as the most abundant amino acid in the body, participates in the biological synthesis of nucleotides and other non-essential amino acids in the process of cell metabolism. Recent studies showed that glutamine metabolic reprogramming is an important signal during cancer development and progression. This metabolic signature in cancer cells can promote the development of cancer by activating multiple signaling pathways and oncogenes. It can also be involved in tumor immune regulation and promote the development of drug resistance to tumors. In this review, we mainly summarize the role of glutamine metabolic reprogramming in tumors, including the regulation of multiple signaling pathways. We further discussed the promising tumor treatment strategy by targeting glutamine metabolism alone or in combination with chemotherapeutics.

Clinicogenomic Landscape of Metastatic Thymic Epithelial Tumors

BACKGROUND

Despite favorable clinical outcomes, a subset of patients with thymic epithelial tumors (TETs) develop metastasis. The Cancer Genome Atlas (TCGA) provides genomic data on primary TETs (pTETs). This study assessed the molecular alterations and uncovered targetable pathways in metastatic TETs (mTETs).

METHODS

From 2015 to 2020, 49 patients with stage IV TETs underwent Clinical Laboratory Improvement Amendments-based sequencing using whole-exome sequencing (n = 33), panel-based testing (n = 12), and/or liquid biopsy (n = 24). Specimens were obtained from a metastatic organ (n = 36) or relapsed primary mediastinal mass (n = 10), whereas four patients underwent a liquid biopsy only. Data on pTETs were derived from the TCGA.

RESULTS

Compared with the pTET data set, patients with mTETs were younger (54 years v 60.5 years, P = .009) and had more aggressive histologies, with the most common tumor type being thymic carcinoma (n = 22, 40.7%) and B3 thymoma (n = 15, 27.8%). GTF2I was the most altered gene in primary thymomas (48.80%, n = 60). In metastatic thymoma and thymic carcinoma, TP53 was the most common genetic alteration (31% and 36%, respectively). In mTETs, the genomic alteration occurred in the TP53/CDK, EGFR/RAS, and PI3K/mTOR pathways. Biopsies obtained from distant metastasis were more commonly found to contain targetable mutations. There was an overlap of 61% (22 of 36) between tissue and liquid biopsy genomic alterations.

CONCLUSION

Clinically actionable genomic alterations are frequently observed in mTETs, indicating a value of repeat biopsy (preferably from a metastatic site of TETs for sequencing at the time of recurrence (TCGA data).

p53-Bad* Fusion Gene Therapy Induces Apoptosis In Vitro and Reduces Zebrafish Tumor Burden in Hepatocellular Carcinoma

With few curative treatments and a global yearly death rate of over 800,000, hepatocellular carcinoma (HCC) desperately needs new therapies. Although wild-type p53 gene therapy has been shown to be safe in HCC patients, it has not shown enough efficacy to merit approval. This work aims to show how p53 can be re-engineered through fusion to the pro-apoptotic BH3 protein Bcl-2 antagonist of cell death (Bad) to improve anti-HCC activity and potentially lead to a novel HCC therapeutic, p53-Bad*. p53-Bad* is a fusion of p53 and Bad, with two mutations, S112A and S136A. We determined mitochondrial localization of p53-Bad* in liver cancer cell lines with varying p53 mutation statuses via fluorescence microscopy. We defined the apoptotic activity of p53-Bad* in four liver cancer cell lines using flow cytometry. To determine the effects of p53-Bad* in vivo, we generated and analyzed transgenic zebrafish expressing hepatocyte-specific p53-Bad*. p53-Bad* localized to the mitochondria regardless of the p53 mutation status and demonstrated superior apoptotic activity over WT p53 in early, middle, and late apoptosis assays. Tumor burden in zebrafish HCC was reduced by p53-Bad* as measured by the liver-to-body mass ratio and histopathology. p53-Bad* induced significant apoptosis in zebrafish HCC as measured by TUNEL staining but did not induce apoptosis in non-HCC fish. p53-Bad* can induce apoptosis in a panel of liver cancer cell lines with varying p53 mutation statuses and induce apoptosis/reduce HCC tumor burden in vivo in zebrafish. p53-Bad* warrants further investigation as a potential new HCC therapeutic.

Importance of lactate dehydrogenase (LDH) and monocarboxylate transporters (MCTs) in cancer cells

Background

In most regions, cancer ranks the second most frequent cause of death following cardiovascular disorders.

Aim

In this article, we review the various aspects of glycolysis with a focus on types of MCTs and the importance of lactate in cancer cells.

Results and Discussion

Metabolic changes are one of the first and most important alterations in cancer cells. Cancer cells use different pathways to survive, energy generation, growth, and proliferation compared to normal cells. The increase in glycolysis, which produces substances such as lactate and pyruvate, has an important role in metastases and invasion of cancer cells. Two important cellular proteins that play a role in the production and transport of lactate include lactate dehydrogenase and monocarboxylate transporters (MCTs). These molecules by their various isoforms and different tissue distribution help to escape the immune system and expansion of cancer cells under different conditions.

p53 Arg72Pro polymorphism, adiposity status, and cancer risk: Two case-cohorts within a Japanese prospective study

The tumor suppressor protein, p53, is a critical molecule involved in cancer development. However, the association between p53 Arg72Pro polymorphism and cancer risk remains unclear, possibly due to the pro-tumor potential of p53 under metabolic stress. Here, we hypothesized that the p53 Arg72Pro polymorphism plays different roles during tumorigenesis by adiposity status. We measured baseline body mass index (BMI) and p53 Arg72Pro polymorphism for two case-cohorts, which included 4264 cancers with up to 20 years of follow-up. Multivariable-adjusted hazard ratios (HRs) and confidence intervals (CIs) were estimated using weighted Cox proportional-hazards method. Without consideration of adiposity status, p53 Arg72Pro polymorphism was not associated with cancer risk. However, proline (Pro) homozygous genotype conferred an increased cancer risk for individuals with a BMI <25 kg/m² (HR [95% CI]: 1.12 [1.00-1.26] for total cancer and 1.19 [1.02-1.38] for obesity-related cancer), but not for those with a BMI ≥ 25 kg/m² . The heterogeneous effect of p53 Arg72Pro polymorphism on cancer risk according to adiposity status was indicated (p_{heterogeneity} : 0.07 for total cancer and 0.03 for obesity-related cancer). Furthermore, the association between overweight and cancer risk was only observed in arginine (Arg) carriers, but not in Pro homozygous carriers (p_{heterogeneity} : 0.07 for total cancer and 0.02 for obesity-related cancer). Pro homozygous carriers were more likely to be predisposed to cancer than Arg carriers with normal-weight conditions. In addition, overweight was related to a higher cancer risk in Arg carriers than Pro homozygous carriers. Our findings may suggest the adiposity-dependent dual effects of p53 Arg72Pro polymorphism during tumorigenesis.

Coordination of the AMPK, Akt, mTOR, and p53 Pathways under Glucose Starvation

Glucose is a direct energy source for eukaryotic cells, and its deficiency elicits complex stress responses and diverse cellular outcomes. Although several signaling pathways involved have been identified, how they coordinately dictate the cell fate remains obscure. We propose a minimal network model for the cellular response to glucose restriction, characterizing the glucose uptake and signaling of the AMPK, Akt, mTOR, and p53 pathways. We demonstrate that in the presence of sufficient growth factors and amino acids, cells may undergo proliferation, senescence, or apoptosis, depending on the extracellular glucose level. AMPK is first activated upon glucose limitation, activating p53 to induce cell-cycle arrest; possibly, cells resume proliferation after timely glucose restoration. For long-term energy stress, cell senescence is maintained by low/intermediate levels of p53 and persistent activation of mTOR and Akt, or cells commit apoptosis when the proteins undergo biphasic dynamics, e.g., p53 switches from intermediate levels to high levels while mTOR and Akt become inactivated in the later phase. The biphasic dynamics of p53 are associated with flipping of two bistable switches. Appropriate mTOR levels are required for optimal cell-fate decision. This work suggests that senescence and apoptosis occur sequentially in glucose-depleted cells, and a theoretical framework is provided for exploring the cellular response to energy stress.