p53 and metabolism

Metabolic Imaging Phenotype Using Radiomics of [18F]FDG PET/CT Associated with Genetic Alterations of Colorectal Cancer

PURPOSE

To understand the association between genetic mutations and radiomics of 2-deoxy-2-[¹⁸F]fluoro-D-glucose ([¹⁸F]FDG) positron emission tomography (PET)/x-ray computed tomography (CT) in patients with colorectal cancer (CRC).

PROCEDURES

This study included 74 CRC patients who had undergone preoperative [¹⁸F]FDG PET/CT. A total of 65 PET/CT-related features including intensity, volume-based, histogram, and textural features were calculated. High-resolution melting methods were used for genetic mutation analysis.

RESULTS

Genetic mutants were found in 21 KRAS tumors (28 %), 31 TP53 tumors (42 %), and 17 APC tumors (23 %). Tumors with a mutated KRAS had an increased value at the 25th percentile of maximal standardized uptake value (SUV_max) within their metabolic tumor volume (MTV) (P < .0001; odds ratio [OR] 1.99; 95 % confidence interval [CI] 1.37-2.90) and their contrast from the gray-level cooccurrence matrix (P = .005; OR 1.52; 95 % CI 1.14-2.04). A mutated TP53 was associated with an increased value of short-run low gray-level emphasis derived from the gray-level run length matrix (P = .001; OR 243006.0; 95 % CI 59.2-996,872,313). APC mutants exhibited lower low gray-level zone emphasis derived from the gray-level zone length matrix (P = .006; OR < .0001; 95 % CI 0.000-0.22).

CONCLUSION

PET/CT-derived radiomics can provide supplemental information to determine KRAS, TP53, and APC genetic alterations in CRC.

Emerging roles of aerobic glycolysis in breast cancer

Altered aerobic glycolysis is a well-recognized characteristic of cancer cell energy metabolism, known as the Warburg effect. Even in the presence of abundant oxygen, a majority of tumor cells produce substantial amounts of energy through a high glycolytic metabolism, and breast cancer (BC) is no exception. Breast cancer continues to be the second leading cause of cancer-associated mortality in women worldwide. However, the precise role of aerobic glycolysis in the development of BC remains elusive. Therefore, the present review attempts to address the implication of key enzymes of the aerobic glycolytic pathway including hexokinase (HK), phosphofructokinase (PFK) and pyruvate kinase (PK), glucose transporters (GLUTs), together with related signaling pathways including protein kinase B(PI3K/AKT), mammalian target of rapamycin (mTOR) and adenosine monophosphate-activated protein kinase (AMPK) and transcription factors (c-myc, p53 and HIF-1) in the research of BC. Thus, the review of aerobic glycolysis in BC may evoke novel ideas for the BC treatment.

MicroRNA-26a targets the mdm2/p53 loop directly in response to liver regeneration

Liver regeneration (LR) is the result of a dynamic balance between the increased proliferation and decreased apoptosis of hepatocytes. However, the role of microRNA (miR)‑26a in regulating complex signalling networks involving E3 ubiquitin‑protein ligase Mdm2 (mdm2), p53, p21 and p27 in the process of LR is currently unclear. In the present study, it was hypothesized that miR‑26a may negatively regulate the mdm2/p53 signalling loop in response to LR. In vitro experiments were performed, whereby mouse liver cells were transfected with an miR‑26a vector or an anti/miR‑26a vector. Cell proliferation was analysed using an MTS assay and cell apoptosis, and cell cycle progression were analysed by flow cytometry. In addition, the expression of mdm2, p53, p21 and p27 were assessed using western blotting and reverse transcription‑quantitative polymerase chain reaction analyses. Dual‑luciferase reporter assays were also used to examine the association between mdm2 and miR‑26a. A 70% partial hepatectomy in C57BL/6J mice was then performed, which was followed by injection with an mdm2‑cDNA vector or an mdm2‑small interfering RNA vector. The liver‑to‑body weight ratio and liver function of mice were measured at 72 h following vector administration. The results demonstrated an increase in hepatocyte proliferation accompanied by decreased hepatocyte apoptosis levels. In addition, inhibition of miR‑26a expression was associated with a marked increase in mdm2 expression, while the expression of p53, p21 and p27 was decreased when compared with negative controls. The opposite effects were observed when miR‑26a was overexpressed. Notably, miR‑26a was demonstrated to target the 3'‑untranslated region of mdm2 directly. The results of the present study are the first to demonstrate as far as the authors are aware that the mdm2/p53 negative feedback loop may be targeted by miR‑26a directly in response to LR, and that mdm2 negatively regulates p53, p21 and p27 but not miR‑26a. miR‑26a may therefore function as an important factor that regulates the interaction between mdm2 and p53.

The role of tumor suppressor p53 in metabolism and energy regulation, and its implication in cancer and lifestyle-related diseases

The tumor suppressor gene p53 is mutated in approximately more than 50% of human cancers. p53 is also referred to as the "cellular gatekeeper" or "guardian of the genome" because it protects the body from spreading mutated genome induced by various stress. When the cells receives stimuli such as DNA damage, oncogene activation, oxidative stress or undernutrition, p53 gives rise to a number of cellular responses, including cell cycle arrest, apoptosis, cellular senescence and metabolic adaptation. Related to energy metabolisms, it has been reported that p53 reduces glycolysis and enhances mitochondrial respiration. p53 is also involved in the regulation of other cellular metabolism and energy production systems: amino acid metabolism, fatty acid metabolism, nucleic acid metabolism, anti-oxidation, mitochondrial quality control, and autophagy. Moreover, recent studies have shown that p53 gene polymorphisms affect life expectancy and lifestyle-related disease such as type 2 diabetes, suggesting that there is a certain relationship between p53 function and metabolic disorders. In addition, mutant p53 protein does not only lose the tumor suppressor function, but it also gains novel oncogenic function and contributes to tumor development, involving cellular metabolism modification. Therefore, the importance of multifunctionality of p53, particularly with regard to intracellular metabolisms, arouses therapeutic interest and calls attention as the key molecule among cancer, lifestyle-related diseases and life expectancy.

MYC Expression and Metabolic Redox Changes in Cancer Cells: A Synergy Able to Induce Chemoresistance

Chemoresistance is due to multiple factors including the induction of a metabolic adaptation of tumor cells. In fact, in these cells, stress conditions induced by therapies stimulate a metabolic reprogramming which involves the strengthening of various pathways such as glycolysis, glutaminolysis and the pentose phosphate pathway. This metabolic reprogramming is the result of a complex network of mechanisms that, through the activation of oncogenes (i.e., MYC, HIF1, and PI3K) or the downregulation of tumor suppressors (i.e., TP53), induces an increased expression of glucose and/or glutamine transporters and of glycolytic enzymes. Therefore, in order to overcome chemoresistance, it is necessary to develop combined therapies which are able to selectively and simultaneously act on the multiple molecular targets responsible for this adaptation. This review is focused on highlighting the role of MYC in modulating the epigenetic redox changes which are crucial in the acquisition of therapy resistance.

Noninvasive assessment and quantification of tumor vascularization using [18F]FDG-PET/CT and CE-CT in a tumor model with modifiable angiogenesis-an animal experimental prospective cohort study

Background

This study investigated the noninvasive assessment of tumor vascularization with clinical F-18-fluorodeoxyglucose positron emission tomography/computed tomography and contrast-enhanced computed tomography ([18F]FDG-PET/CT and CE-CT) in experimental human xenograft tumors with modifiable vascularization and compared results to histology. Tumor xenografts with modifiable vascularization were established in 71 athymic nude rats by subcutaneous transplantation of human non-small-cell lung cancer (NSCLC) cells. Four different groups were transplanted with two different tumor cell lines (either A549 or H1299) alone or tumors co-transplanted with rat glomerular endothelial (RGE) cells, the latter to increase vascularization. Tumors were assessed noninvasively by [18F]FDG PET/CT and contrast-enhanced CT (CE-CT) using clinical scanners. This was followed by histological examinations evaluating tumor vasculature (CD-31 and intravascular fluorescent beads).

Results

In both tumor lines (A549 and H1299), co-transplantation of RGE cells resulted in faster growth rates [maximal tumor diameter of 20 mm after 22 (± 1.2) as compared to 45 (± 1.8) days, p < 0.001], higher microvessel density (MVD) determined histologically after CD-31 staining [171.4 (± 18.9) as compared to 110.8 (± 11) vessels per mm², p = 0.002], and higher perfusion as indicated by the number of beads [1.3 (± 0.1) as compared to 1.1 (± 0.04) beads per field of view, p = 0.001]. In [18F]FDG-PET/CT, co-transplanted tumors revealed significantly higher standardized uptake values [SUVmax, 2.8 (± 0.2) as compared to 1.1 (± 0.1), p < 0.001] and larger metabolic active volumes [2.4 (± 0.2) as compared to 0.4 (± 0.2) cm³, p < 0.001] than non-co-transplanted tumors. There were significant correlations for vascularization parameters derived from histology and [18F]FDG PET/CT [beads and SUVmax, r = 0.353, p = 0.005; CD-31 and SUVmax, r = 0.294, p = 0.036] as well as between CE-CT and [18F]FDG PET/CT [contrast enhancement and SUVmax, r = 0.63, p < 0.001; vital CT tumor volume and metabolic PET tumor volume, r = 0.919, p < 0.001].

Conclusions

In this study, a human xenograft tumor model with modifiable vascularization implementable for imaging, pharmacological, and radiation therapy studies was successfully established. Both [18F]FDG-PET/CT and CE-CT are capable to detect parameters closely connected to the degree of tumor vascularization, thus they can help to evaluate vascularization in tumors noninvasively. [18F]FDG-PET may be considered for characterization of tumors beyond pure glucose metabolism and have much greater contribution to diagnostics in oncology.

Release of volatile organic compounds (VOCs) from colorectal cancer cell line LS174T

Colorectal cancer (CRC) is the third most common cancer worldwide. To date, no non-invasive and specific biomarkers have been identified for the diagnosis of CRC. The analysis of volatile organic compounds (VOCs) is attracting increasing attention and provides the possibility of a non-invasive diagnosis. Solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) have been used to analyze the VOCs released from the headspace gas of LS174T (Dukes' type B colorectal adenocarcinoma) cells, arsenic trioxide (ATO)-treated LS174T cells and the blood from tumor-bearing mice. The data were processed using principal component analysis (PCA) and orthogonal partial least-squares discriminant analysis (OPLS-DA), which showed that the levels of decanal, 2,4-dimethyl- heptane, and twelve other metabolites were significantly greater in the headspace gas of the LS174T cells and blood of tumor-bearing mice. Additionally, in vivo experiments indicated that formic acid, ethenyl ester and p-trimethylsilyloxyphenyl-(trimethylsilyloxy)trimethylsilylacrylate were consumed during tumor growth. In conclusion, VOCs such as 1-methoxy-hexane and 2,4-dimethyl-heptane could be useful diagnostic markers for CRC. Further research should focus on the potential metabolic pathways associated with these profiles.

Sestrin 2 protects against metabolic stress in a p53-independent manner

Glucose limitation activates p53, which functions as an adaptive response to maintain cell survival. However, p53 is frequently deleted or mutated in a variety of tumors, while most cancer cells can acclimatize themselves to metabolically unfavorable surrounding, indicating that alternative mechanisms other than p53 transactivation underly adaptive response of cancer cells with p53 deletion or mutation to metabolically hostile environment. Sestrin 2 (SESN2) is a p53 downstream target, which plays a protective role against various stressful stimuli, such as genotoxic, energetic, and oxidative stress. In the current study, we demonstrated that SESN2 transcript was stabilized by glucose limitation at the posttranscriptional level irrespective of p53 status. Importantly, SESN2 also protected cells from metabolic stress triggered by glucose limitation in a p53-independent manner. Our data indicated that stabilization of SESN2 transcript might be an alternative adaptive response to metabolic stress other than p53 activation. Thereby, the current study highlights the significance of stabilization of SESN2 transcript in adaptation of cells with p53 deletion or mutation to metabolic stress.

Wild type- and mutant p53 proteins in mitochondrial dysfunction: emerging insights in cancer disease

Deregulated cell metabolism is one of the cancer hallmarks. Mitochondrial DNA mutations and enzyme defects, aberrant tumor suppressor or oncogenic activities cause mitochondrial dysfunction leading to deregulated cellular energetics. The tumor suppressor protein, p53 is a tetrameric transcription factor that in response to diverse genotoxic and non-genotoxic insults activates a plethora of target genes to preserve genome integrity. In the last two decades the discovery of cytoplasmic p53 localization focused intense research on its extra-nuclear functions. The ability of p53 to induce apoptosis acting directly at mitochondria and the related mechanisms of p53 localization and translocation in the cytoplasm have been investigated. A role of cytoplasmic p53 in autophagy, pentose phosphate pathway, fatty acid synthesis and oxidation, and drug response has been proposed. TP53 gene is mutated in more than half of human cancers. In parallel to loss of tumor suppressive functions, mutant p53 proteins often gain new tumorigenic activities (GOF, gain of function). It has been recently shown that mutant p53 proteins mediate metabolic changes thereby promoting cancer development and metastases. Here we review the contribution of either wild-type p53 or mutant p53 proteins to the fine-tuning of mitochondrial metabolism of both normal and cancer cells. Greater knowledge at the mechanistic level might provide insights to develop new cancer therapeutic approaches.

Refractory Lactic Acidosis and an Approach to its Management - A Case Report

Background

Lactic acidosis (LA) is a complication of diseases commonly seen in intensive care patients which carries an increased risk of mortality. It is classified by its pathophysiology; Type A results from tissue hypo-perfusion and hypoxia, and Type B results from abnormal metabolic activity in the absence of hypoxia. Reports of the co-occurrence of both types have been rarely reported in the literature relating to intensive care patients. This case report describes the challenging management of a patient diagnosed with both Type A and Type B LA.

Case presentation

A 55-year-old female with newly diagnosed diffuse large B-cell lymphoma (DLBCL) developed hospital-acquired pneumonia, respiratory failure, shock and intra-abdominal septicaemia from a bowel perforation. Blood gases revealed a mixed picture lactic acidosis. Correction of septic shock, respiratory failure and surgical repair caused initial improvement to the lactic acidosis, but this gradually worsened in the intensive care unit. Only upon starting chemotherapy and renal replacement therapy was full resolution of the lactic acidosis achieved. The patient was discharged but succumbed to her DLBCL several months later.

Conclusion

Type A and Type B LA can co-occur, making management difficult. A systematic approach can help diagnose any underlying pathology and aid in early management.

p53-TP53-Induced Glycolysis Regulator Mediated Glycolytic Suppression Attenuates DNA Damage and Genomic Instability in Fanconi Anemia Hematopoietic Stem Cells

Emerging evidence has shown that resting quiescent hematopoietic stem cells (HSCs) prefer to utilize anaerobic glycolysis rather than mitochondrial respiration for energy production. Compelling evidence has also revealed that altered metabolic energetics in HSCs underlies the onset of certain blood diseases; however, the mechanisms responsible for energetic reprogramming remain elusive. We recently found that Fanconi anemia (FA) HSCs in their resting state are more dependent on mitochondrial respiration for energy metabolism than on glycolysis. In the present study, we investigated the role of deficient glycolysis in FA HSC maintenance. We observed significantly reduced glucose consumption, lactate production, and ATP production in HSCs but not in the less primitive multipotent progenitors or restricted hematopoietic progenitors of Fanca^−/− and Fancc^−/− mice compared with that of wild‐type mice, which was associated with an overactivated p53 and TP53‐induced glycolysis regulator, the TIGAR‐mediated metabolic axis. We utilized Fanca^−/− HSCs deficient for p53 to show that the p53‐TIGAR axis suppressed glycolysis in FA HSCs, leading to enhanced pentose phosphate pathway and cellular antioxidant function and, consequently, reduced DNA damage and attenuated HSC exhaustion. Furthermore, by using Fanca^−/− HSCs carrying the separation‐of‐function mutant p53^R172P transgene that selectively impairs the p53 function in apoptosis but not cell‐cycle control, we demonstrated that the cell‐cycle function of p53 was not required for glycolytic suppression in FA HSCs. Finally, ectopic expression of the glycolytic rate‐limiting enzyme PFKFB3 specifically antagonized p53‐TIGAR‐mediated metabolic reprogramming in FA HSCs. Together, our results suggest that p53‐TIGAR metabolic axis‐mediated glycolytic suppression may play a compensatory role in attenuating DNA damage and proliferative exhaustion in FA HSCs. stem cells2019;37:937–947

Modulation of Host Cell Metabolism by Chlamydia trachomatis

Propagation of the intracellular bacterial pathogen Chlamydia trachomatis is strictly bound to its host cells. The bacterium has evolved by minimizing its genome size at the cost of being completely dependent on its host. Many of the vital nutrients are synthesized only by the host, and this has complex implications. Recent advances in loss-of-function analyses and the metabolomics of human infected versus noninfected cells have provided comprehensive insight into the molecular changes that host cells undergo during the stage of infection. Strikingly, infected cells acquire a stage of high metabolic activity, featuring distinct aspects of the Warburg effect, a condition originally assigned to cancer cells. This condition is characterized by aerobic glycolysis and an accumulation of certain metabolites, altogether promoting the synthesis of crucial cellular building blocks, such as nucleotides required for DNA and RNA synthesis. The altered metabolic program enables tumor cells to rapidly proliferate as well as C. trachomatis-infected cells to feed their occupants and still survive. This program is largely orchestrated by a central control board, the tumor suppressor protein p53. Its downregulation in C. trachomatis-infected cells or mutation in cancer cells not only alters the metabolic state of cells but also conveys the prevention of programmed cell death involving mitochondrial pathways. While this points toward common features in the metabolic reprogramming of infected and rapidly proliferating cells, it also forwards novel treatment options against chronic intracellular infections involving well-characterized host cell targets and established drugs.

A Metabolism Toolbox for CAR T Therapy

The adoptive transfer of T cells expressing chimeric antigen receptors (CARs) through genetic engineering is one of the most promising new therapies for treating cancer patients. A robust CAR T cell-mediated anti-tumor response requires the coordination of nutrient and energy supplies with CAR T cell expansion and function. However, the high metabolic demands of tumor cells compromise the function of CAR T cells by competing for nutrients within the tumor microenvironment (TME). To substantially improve clinical outcomes of CAR T immunotherapy while treating solid tumors, it is essential to metabolically prepare CAR T cells to overcome the metabolic barriers imposed by the TME. In this review, we discuss a potential metabolism toolbox to improve the metabolic fitness of CAR T cells and maximize the efficacy of CAR T therapy.

The histone demethylase JMJD2B is critical for p53-mediated autophagy and survival in Nutlin-treated cancer cells

Autophagy promotes cancer cell survival in response to p53 activation by the anticancer agent Nutlin-3a (Nutlin). We reported previously that Nutlin kills MDM2-amplified cancer cells and that this killing is associated with an inhibition of glucose metabolism, reduced α-ketoglutarate (α-KG) levels, and reduced autophagy. In the current report, using SJSA1, U2OS, A549, and MHM cells, we found that Nutlin alters histone methylation in an MDM2 proto-oncogene-dependent manner and that this, in turn, regulates autophagy-related gene (ATG) expression and cell death. In MDM2-amplified cells, Nutlin increased histone (H) 3 lysine (K) 9 and K36 trimethylation (me3) coincident with reduced autophagy and increased apoptosis. Blocking histone methylation restored autophagy and rescued these cells from Nutlin-induced killing. In MDM2-nonamplified cells, H3K9me3 and H3K36me3 levels were either reduced or not changed by the Nutlin treatment, and this coincided with increased autophagy and cell survival. Blocking histone demethylation reduced autophagy and sensitized these cells to Nutlin-induced killing. Further experiments suggested that MDM2 amplification increases histone methylation in Nutlin-treated cells by causing depletion of the histone demethylase Jumonji domain-containing protein 2B (JMJD2B). Finally, JMJD2B knockdown or inhibition increased H3K9/K36me3 levels, decreased ATG gene expression and autophagy, and sensitized MDM2-nonamplified cells to apoptosis. Together, these results support a model in which MDM2- and JMJD2B-regulated histone methylation levels modulate ATG gene expression, autophagy, and cell fate in response to the MDM2 antagonist Nutlin-3a.

AMP-activated protein kinase regulates cancer cell growth and metabolism via nuclear and mitochondria events

Adenine monophosphate‐activated protein kinase (AMPK) is a fuel sensing enzyme that is activated in shortage of energy and inhibited in its surplus. Cancer is a metabolic disease characteristic of aerobic glycolysis, namely Warburg effect, and possesses heterogeneity featured by spatiotemporal hypoxia and normoxia, where AMPK is deeply implicated. The present study delineates the regulation of mitochondrial functions by AMPK in cancer cells. On the one hand, AMPKα subunit binds to mitochondria independently of β subunit and targeting AMPK to mitochondria facilitates oxidative phosphorylation and fatty acid oxidation, and inhibits glycolysis. As such, mitochondrial AMPK inhibits the growth of cancer cells and tumorigenesis. On the other hand, ablation of the β subunits completely abolishes AMPK activity and simultaneously leads to decreases in mitochondria DNA and protein contents. The effect of the β deletion is rescued by overexpression of the active mutant of bulky AMPKα1 subunit. In conjunction, the transcriptional factors PGC1α and Nrf‐1 are up‐regulated by LKB1/AMPK, an event that is abolished in the absence of the β subunits. Intriguingly, the stimulation of mitochondria biogenesis is not achieved by mitochondria‐targeted AMPK. Therefore, our study suggests that AMPK inhibits cancer cell growth and tumorigenesis via regulation of mitochondria‐mediated metabolism.

Zinc cooperates with p53 to inhibit the activity of mitochondrial aconitase through reactive oxygen species accumulation

Metabolic reprogramming is a central hallmark of cancer. Therefore, targeting metabolism may provide an effective strategy for identifying promising drug targets for cancer treatment. In prostate cancer, cells undergo metabolic transformation from zinc‐accumulating, citrate‐producing cells to citrate‐oxidizing malignant cells with lower zinc levels and higher mitochondrial aconitase (ACO2) activity. ACO2 is a Krebs cycle enzyme that converts citrate to isocitrate and is sensitive to reactive oxygen species (ROS)‐mediated damage. In this study, we found that the expression of ACO2 is positively correlated with the malignancy of prostate cancer. Both zinc and p53 can lead to an increase in ROS. ACO2 can be a target for remodeling metabolism by sensing changes in the ROS levels of prostate cancer. Our results indicate that targeting ACO2 through zinc and p53 can change prostate cancer metabolism, and thus provides a potential new therapeutic strategy for prostate cancer.

PD-L1 on invasive fibroblasts drives fibrosis in a humanized model of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive disease with unremitting extracellular matrix deposition, leading to a distortion of pulmonary architecture and impaired gas exchange. Fibroblasts from IPF patients acquire an invasive phenotype that is essential for progressive fibrosis. Here, we performed RNA sequencing analysis on invasive and noninvasive fibroblasts and found that the immune checkpoint ligand CD274 (also known as PD-L1) was upregulated on invasive lung fibroblasts and was required for the invasive phenotype of lung fibroblasts, is regulated by p53 and FAK, and drives lung fibrosis in a humanized IPF model in mice. Activating CD274 in IPF fibroblasts promoted invasion in vitro and pulmonary fibrosis in vivo. CD274 knockout in IPF fibroblasts and targeting CD274 by FAK inhibition or CD274-neutralizing antibodies blunted invasion and attenuated fibrosis, suggesting that CD274 may be a novel therapeutic target in IPF.

p53/Lactate dehydrogenase A axis negatively regulates aerobic glycolysis and tumor progression in breast cancer expressing wild-type p53

Tumor suppressor p53 is a master regulator of apoptosis and plays key roles in cell cycle checkpoints. p53 responds to metabolic changes and alters metabolism through several mechanisms in cancer. Lactate dehydrogenase A (LDHA), a key enzyme in glycolysis, is highly expressed in a variety of tumors and catalyzes pyruvate to lactate. In the present study, we first analyzed the association and clinical significance of p53 and LDHA in breast cancer expressing wild-type p53 (wt-p53) and found that LDHA mRNA levels are negatively correlated with wt-p53 but not with mutation p53 mRNA levels, and low p53 and high LDHA expression are significantly associated with poor overall survival rates. Furthermore, p53 negatively regulates LDHA expression by directly binding its promoter region. Moreover, a series of LDHA gain-of-function and rescore experiments were carried out in breast cancer MCF7 cells expressing endogenous wt-p53, showing that ectopic expression of p53 decreases aerobic glycolysis, cell proliferation, migration, invasion and tumor formation of breast cancer cells and that restoration of the expression of LDHA in p53-overexpressing cells could abolish the suppressive effect of p53 on aerobic glycolysis and other malignant phenotypes. In conclusion, our findings showed that repression of LDHA induced by wt-p53 blocks tumor growth and invasion through downregulation of aerobic glycolysis in breast cancer, providing new insights into the mechanism by which p53 contributes to the development and progression of breast cancer.

Sensors for Lung Cancer Diagnosis

The positive outcome of lung cancer treatment is strongly related to the earliness of the diagnosis. Thus, there is a strong requirement for technologies that could provide an early detection of cancer. The concept of early diagnosis is immediately extended to large population screening, and then, it is strongly related to non-invasiveness and low cost. Sensor technology takes advantage of the microelectronics revolution, and then, it promises to develop devices sufficiently sensitive to detect lung cancer biomarkers. A number of biosensors for the detection of cancer-related proteins have been demonstrated in recent years. At the same time, the interest is growing towards the analysis of volatile metabolites that could be measured directly from the breath. In this paper, a review of the state-of-the-art of biosensors and volatile compound sensors is presented.

p53/BNIP3-dependent mitophagy limits glycolytic shift in radioresistant cancer

The role of p53 in genotoxic therapy-induced metabolic shift in cancers is not yet known. In this study, we investigated the role of p53 in the glycolytic shift in head and neck squamous cell carcinoma cell lines following irradiation. Isogenic p53-null radioresistant cancer cells established through cumulative irradiation showed decreased oxygen consumption and increased glycolysis with compromised mitochondria, corresponding with their enhanced sensitivity to drugs that target glycolysis. In contrast, radioresistant cancer cells with wild-type p53 preserved their primary metabolic profile with intact mitophagic processes and maintained their mitochondrial integrity. Moreover, we identified a previously unappreciated link between p53 and mitophagy, which limited the glycolytic shift through the BNIP3-dependent clearance of abnormal mitochondria. Thus, drugs targeting glycolysis could be used as an alternative strategy for overcoming radioresistant cancers, and the p53 status could be used as a biomarker for selecting participants for clinical trials.

Principles of Exercise Prescription, and How They Influence Exercise-Induced Changes of Transcription Factors and Other Regulators of Mitochondrial Biogenesis

Physical inactivity represents the fourth leading risk factor for mortality, and it has been linked with a series of chronic disorders, the treatment of which absorbs ~ 85% of healthcare costs in developed countries. Conversely, physical activity promotes many health benefits; endurance exercise in particular represents a powerful stimulus to induce mitochondrial biogenesis, and it is routinely used to prevent and treat chronic metabolic disorders linked with sub-optimal mitochondrial characteristics. Given the importance of maintaining a healthy mitochondrial pool, it is vital to better characterize how manipulating the endurance exercise dose affects cellular mechanisms of exercise-induced mitochondrial biogenesis. Herein, we propose a definition of mitochondrial biogenesis and the techniques available to assess it, and we emphasize the importance of standardizing biopsy timing and the determination of relative exercise intensity when comparing different studies. We report an intensity-dependent regulation of exercise-induced increases in nuclear peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) protein content, nuclear phosphorylation of p53 (serine 15), and PGC-1α messenger RNA (mRNA), as well as training-induced increases in PGC-1α and p53 protein content. Despite evidence that PGC-1α protein content plateaus within a few exercise sessions, we demonstrate that greater training volumes induce further increases in PGC-1α (and p53) protein content, and that short-term reductions in training volume decrease the content of both proteins, suggesting training volume is still a factor affecting training-induced mitochondrial biogenesis. Finally, training-induced changes in mitochondrial transcription factor A (TFAM) protein content are regulated in a training volume-dependent manner and have been linked with training-induced changes in mitochondrial content.

p53 Represses the Mevalonate Pathway to Mediate Tumor Suppression

There are still gaps in our understanding of the complex processes by which p53 suppresses tumorigenesis. Here we describe a novel role for p53 in suppressing the mevalonate pathway, which is responsible for biosynthesis of cholesterol and nonsterol isoprenoids. p53 blocks activation of SREBP-2, the master transcriptional regulator of this pathway, by transcriptionally inducing the ABCA1 cholesterol transporter gene. A mouse model of liver cancer reveals that downregulation of mevalonate pathway gene expression by p53 occurs in premalignant hepatocytes, when p53 is needed to actively suppress tumorigenesis. Furthermore, pharmacological or RNAi inhibition of the mevalonate pathway restricts the development of murine hepatocellular carcinomas driven by p53 loss. Like p53 loss, ablation of ABCA1 promotes murine liver tumorigenesis and is associated with increased SREBP-2 maturation. Our findings demonstrate that repression of the mevalonate pathway is a crucial component of p53-mediated liver tumor suppression and outline the mechanism by which this occurs.

Metabolic rewiring beyond Warburg in chronic lymphocytic leukemia: How much do we actually know?

Chronic Lymphocytic Leukemia (CLL) is the most common adult leukemia in the western world. CLL consists of the accumulation of malignant B-cells in the blood stream and homing tissues. Although treatable, this disease is not curable, and resistance or relapse is often present. In many cancers, the study of metabolic reprograming has uncovered novel targets that are already being exploited in the clinic. However, CLL metabolism is still poorly understood. The ability of CLL lymphocytes to adapt to diverse microenvironments is accompanied by modifications in cell metabolism, revealing the challenge of targeting the CLL lymphocytes present in all different compartments. Despite this, the study of CLL metabolism led to an ongoing clinical trial using glucose uptake and mitochondrial respiration inhibitors. In contrast, glutamine and fatty acid metabolism remain to be further exploited in CLL. Here, we summarize the present knowledge of CLL metabolism, as well as the metabolic influence of Myc, ATM and p53 on CLL lymphocytes.

Centromere protein F (CENPF), a microtubule binding protein, modulates cancer metabolism by regulating pyruvate kinase M2 phosphorylation signaling

Prostate cancer (PC) is the most commonly diagnosed cancer in men and is the second leading cause of male cancer-related death in North America. Metabolic adaptations in malignant PC cells play a key role in fueling the growth and progression of the disease. Unfortunately, little is known regarding these changes in cellular metabolism. Here, we demonstrate that centromere protein F (CENPF), a protein associated with the centromere-kinetochore complex and chromosomal segregation during mitosis, is mechanically linked to altered metabolism and progression in PC. Using the CRISPR-Cas9 system, we silenced the gene for CENPF in human PC3 cells. These cells were found to have reduced levels of epithelial-mesenchymal transition markers and inhibited cell proliferation, migration, and invasion. Silencing of CENPF also simultaneously improved sensitivity to anoikis-induced apoptosis. Mass spectrometry analysis of tyrosine phosphorylated proteins from CENPF knockout (CENPFKO) and control cells revealed that CENPF silencing increased inactive forms of pyruvate kinase M2, a rate limiting enzyme needed for an irreversible reaction in glycolysis. Furthermore, CENPFKO cells had reduced global bio-energetic capacity, acetyl-CoA production, histone acetylation, and lipid metabolism, suggesting that CENPF is a critical regulator of cancer metabolism, potentially through its effects on mitochondrial functioning. Additional quantitative immunohistochemistry and imaging analyzes on a series of PC tumor microarrays demonstrated that CENPF expression is significantly increased in higher-risk PC patients. Based on these findings, we suggest the CENPF may be an important regulator of PC metabolism through its role in the mitochondria.

Expression of the Alternative Oxidase Influences Jun N-Terminal Kinase Signaling and Cell Migration

Downregulation of Jun N-terminal kinase (JNK) signaling inhibits cell migration in diverse model systems. In Drosophila pupal development, attenuated JNK signaling in the thoracic dorsal epithelium leads to defective midline closure, resulting in cleft thorax. Here we report that concomitant expression of the Ciona intestinalis alternative oxidase (AOX) was able to compensate for JNK pathway downregulation, substantially correcting the cleft thorax phenotype. AOX expression also promoted wound-healing behavior and single-cell migration in immortalized mouse embryonic fibroblasts (iMEFs), counteracting the effect of JNK pathway inhibition. However, AOX was not able to rescue developmental phenotypes resulting from knockdown of the AP-1 transcription factor, the canonical target of JNK, nor its targets and had no effect on AP-1-dependent transcription. The migration of AOX-expressing iMEFs in the wound-healing assay was differentially stimulated by antimycin A, which redirects respiratory electron flow through AOX, altering the balance between mitochondrial ATP and heat production. Since other treatments affecting mitochondrial ATP did not stimulate wound healing, we propose increased mitochondrial heat production as the most likely primary mechanism of action of AOX in promoting cell migration in these various contexts.

Inhibition of MUC1-C regulates metabolism by AKT pathway in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is one of the most common digestive tumors worldwide. The Mucin 1 (MUC1) heterodimeric protein has been confirmed that is overexpressed in ESCC and induced adverse outcomes. However, the detailed mechanism(s) remained challenging. So, we investigated the relationship between MUC1‐C and metabolism in ESCC cells. In the results, TP53‐induced glycolysis and apoptosis regulator (TIGAR) was overexpressed and correlative with MUC1‐C positively in ESCC tissue. Targeting MUC1‐C inhibits AKT–mTORC–S6K1 signaling and blocks TIGAR translation. We found that the inhibitory effect of GO‐203 on TIGAR was mediated by inhibition of AKT–mTOR–S6K1 pathway. The findings also demonstrated that the suppressive effect of GO‐203 on TIGAR is related to the decrease of glutathione level, the increase of reactive oxygen species and the loss of mitochondrial transmembrane membrane potential. In xenograft tissues, GO‐203 inhibited the growth of ESCC cells and lead to the low expression of transmembrane C‐terminal subunit (MUC1‐C) and TIGAR. This evidence supports the contention that MUC1‐C is significant for metabolism in ESCC and indicated that MUC1‐C is a potential target for the treatment of ESCC.

Colorectal Cancer and Metabolism

Purpose of Review

Metabolic reprogramming is essential for the rapid proliferation of cancer cells and is thus recognized as a hallmark of cancer. In this review, we will discuss the etiologies and effects of metabolic reprogramming in colorectal cancer.

Recent Findings

Changes in cellular metabolism may precede the acquisition of driver mutations ultimately leading to colonocyte transformation. Oncogenic mutations and loss of tumor suppressor genes further reprogram CRC cells to upregulate glycolysis, glutaminolysis, one-carbon metabolism, and fatty acid synthesis. These metabolic changes are not uniform throughout tumors, as subpopulations of tumor cells may rely on different pathways to adapt to nutrient availability in the local tumor microenvironment. Finally, metabolic cross-communication between stromal cells, immune cells, and the gut microbiota enable CRC growth, invasion, and metastasis.

Summary

Altered cellular metabolism occurs in CRC at multiple levels, including in the cells that make up the bulk of CRC tumors, cancer stem cells, the tumor microenvironment, and host-microbiome interactions. This knowledge may inform the development of improved screening and therapeutics for CRC.

Inverted mirror image molecular beacon-based three concatenated logic gates to detect p53 tumor suppressor gene

Mutation of p53 tumor suppressor gene represents one of the early molecular events in tumor initiation and progression. Although molecular computing holds tremendous potential with important applications in diagnosis, prognosis and treatment of human diseases at the molecular level, designing molecular logic gates to implement cascade amplification via operating autonomously for the detection of point mutations still remains challenging. In this contribution, we developed a three concatenated logic gates (TCLG) to perform multiple strand displacement amplification (m-SDA) for screening the cancer-related point mutations only via designing an innovative molecular beacon (MB). Specifically, using p53 gene as model target, extending the two ends of a MB via adding two fragments with the same sequence achieves two unique terminal single-stranded (ss) overhangs. After self-folding of MB into hairpin structure, the two overhangs exhibit a near inverted mirror image (IM) relationship if taking the base nature and direction into account. For this, the probe is called IM-MB. Because cascade SDAs can occur on IM-MB and promote each other, the target gene can be detected down to 10 pM. Along this line, the TCLG circuit was proposed, and two primers and target gene serve as the indispensable input signals. Utilizing this logic circuit, the point mutation or absence of target gene can be sensitively screened. Moreover, its potential application in the recognition of point mutations in complex biomatrix has been demonstrated via blind test. The proof-of-concept scheme is expected to provide new insight into the development of DNA-based molecular logic gates and their applications in basic research, medical diagnosis and precise treatment and treatment of genetic diseases.

Mutant p53-dependent mitochondrial metabolic alterations in a mesenchymal stem cell-based model of progressive malignancy

It is well accepted that malignant transformation is associated with unique metabolism. Malignant transformation involves a variety of cellular pathways that are associated with initiation and progression of the malignant process that remain to be deciphered still. Here we used a mouse model of mutant p53 that presents a stepwise progressive transformation of adult Mesenchymal Stem Cells (MSCs). While the established parental p53Mut-MSCs induce tumors, the parental p53WT-MSCs that were established in parallel, did not. Furthermore, tumor lines derived from the parental p53Mut-MSCs (p53Mut-MSC-TLs), exhibited yet a more aggressive transformed phenotype, suggesting exacerbation in tumorigenesis. Metabolic tracing of these various cell types, indicated that while malignant transformation is echoed by a direct augmentation in glycolysis, the more aggressive p53Mut-MSC-TLs demonstrate increased mitochondrial oxidation that correlates with morphological changes in mitochondria mass and function. Finally, we show that these changes are p53Mut-dependent. Computational transcriptional analysis identified a mitochondrial gene signature specifically downregulated upon knock/out of p53Mut in MSC-TLs. Our results suggest that stem cells exhibiting different state of malignancy are also associated with a different quantitative and qualitative metabolic profile in a p53Mut-dependent manner. This may provide important insights for cancer prognosis and the use of specific metabolic inhibitors in a personalized designed cancer therapy.

Training-Induced Changes in Mitochondrial Content and Respiratory Function in Human Skeletal Muscle

A sedentary lifestyle has been linked to a number of metabolic disorders that have been associated with sub-optimal mitochondrial characteristics and an increased risk of premature death. Endurance training can induce an increase in mitochondrial content and/or mitochondrial functional qualities, which are associated with improved health and well-being and longer life expectancy. It is therefore important to better define how manipulating key parameters of an endurance training intervention can influence the content and functionality of the mitochondrial pool. This review focuses on mitochondrial changes taking place following a series of exercise sessions (training-induced mitochondrial adaptations), providing an in-depth analysis of the effects of exercise intensity and training volume on changes in mitochondrial protein synthesis, mitochondrial content and mitochondrial respiratory function. We provide evidence that manipulation of different exercise training variables promotes specific and diverse mitochondrial adaptations. Specifically, we report that training volume may be a critical factor affecting changes in mitochondrial content, whereas relative exercise intensity is an important determinant of changes in mitochondrial respiratory function. As a consequence, a dissociation between training-induced changes in mitochondrial content and mitochondrial respiratory function is often observed. We also provide evidence that exercise-induced changes are not necessarily predictive of training-induced adaptations, we propose possible explanations for the above discrepancies and suggestions for future research.

Simvastatin interferes with cancer 'stem-cell' plasticity reducing metastasis in ovarian cancer

Cell plasticity of 'stem-like' cancer-initiating cells (CICs) is a hallmark of cancer, allowing metastasis and cancer progression. Here, we studied whether simvastatin, a lipophilic statin, could impair the metastatic potential of CICs in high-grade serous ovarian cancer (HGS-ovC), the most lethal among the gynecologic malignancies. qPCR, immunoblotting and immunohistochemistry were used to assess simvastatin effects on proteins involved in stemness and epithelial-mesenchymal cell plasticity (EMT). Its effects on tumor growth and metastasis were evaluated using different models (e.g., spheroid formation and migration assays, matrigel invasion assays, 3D-mesomimetic models and cancer xenografts). We explored also the clinical benefit of statins by comparing survival outcomes among statin users vs non-users. Herein, we demonstrated that simvastatin modifies the stemness and EMT marker expression patterns (both in mRNA and protein levels) and severely impairs the spheroid assembly of CICs. Consequently, CICs become less metastatic in 3D-mesomimetic models and show fewer ascites/tumor burden in HGS-ovC xenografts. The principal mechanism behind statin-mediated effects involves the inactivation of the Hippo/YAP/RhoA pathway in a mevalonate synthesis-dependent manner. From a clinical perspective, statin users seem to experience better survival and quality of life when compared with non-users. Considering the high cost and the low response rates obtained with many of the current therapies, the use of orally or intraperitoneally administered simvastatin offers a cost/effective and safe alternative to treat and potentially prevent recurrent HGS-ovCs.

Dysregulation of Glucose Metabolism by Oncogenes and Tumor Suppressors in Cancer Cells

Cancers are complex diseases having several unique features, commonly described as ‘hallmarks of cancer’. Among them, altered signaling pathways are the common characteristic features that drive cancer progression; this is achieved due to mutations that lead to the activation of growth promoting(s) oncogenes and inactivation of tumor suppressors. As a result of which, cancer cells increase their glycolytic rate by consuming a large amount of glucose, and convert a majority of glucose to lactate even in the presence of oxygen known as the “Warburg effect”. Tumor cells like other cells are strictly dependent on energy for growth and survival; therefore, understanding energy metabolism will give us an idea to develop new effective anti-cancer therapies that target cancer energy production pathways. This review summarizes the roles of tumor suppressors and oncogenes and their products that provide metabolic advantages to cancer cells which in turn leads to the establishment of the “Warburg effect” and ultimately leads to cancer progression. Understanding cancer cell’s vulnerability will provide potential targets for its control.

Ibrutinib Resistance Is Reduced by an Inhibitor of Fatty Acid Oxidation in Primary CLL Lymphocytes

Chronic Lymphocytic Leukemia (CLL) is an incurable disease, characterized by the accumulation of malignant B-lymphocytes in the blood stream (quiescent state) and homing tissues (where they can proliferate). In CLL, the targeting of B-cell receptor signaling through a Burton's tyrosine kinase inhibitor (ibrutinib) has rendered outstanding clinical results. However, complete remission is not guaranteed due to drug resistance or relapse, revealing the need for novel approaches for CLL treatment. The characterization of metabolic rewiring in proliferative cancer cells is already being applied for diagnostic and therapeutic purposes, but our knowledge of quiescent cell metabolism—relevant for CLL cells—is still fragmentary. Recently, we reported that glutamine metabolism in primary CLL cells bearing the del11q deletion is different from their del11q negative counterparts, making del11q cells especially sensitive to glutaminase and glycolysis inhibitors. In this work, we used our primary CLL lymphocyte bank and compounds interfering with central carbon metabolism to define metabolic traits associated with ibrutinib resistance. We observe a differential basal metabolite uptake linked to ibrutinib resistance, favoring glutamine uptake and catabolism. Upon ibrutinib treatment, the redox balance in ibrutinib resistant cells is shifted toward NADPH accumulation, without an increase in glutamine uptake, suggesting alternative metabolic rewiring such as the activation of fatty acid oxidation. In accordance to this idea, the curtailing of fatty acid oxidation by CPT1 inhibition (etomoxir) re-sensitized resistant cells to ibrutinib. Our results suggest that fatty acid oxidation could be explored as a target to overcome ibrutinib resistance.

Human cellular mitochondrial remodelling is governed by miR-2909 RNomics

BACKGROUND

There exists a general recognition of the fact that mitochondrial remodelling as a result of aerobic glycolysis ensures human somatic cells to revert to a more primitive-form exhibiting stem-like phenotype. The present study is an attempt to demonstrate that miR-2909 RNomics within human peripheral blood mononuclear cells (PBMCs) has the inherent capacity to re-program these cells to exhibit mitochondrial remodelling paralleled by aerobic glycolysis together with intracellular lipid inclusions. Such re-programmed PBMCs also expressed genes having ability to sustain their de-differentiation state and survival.

MATERIAL AND METHODS

Human PBMCs were programed to ectopically express miR-2909. Expression levels of genes including glucose transporter-1 (Glut-1), hexokinase (HK), hypoxia inducia factor-1 (HIF-1α), c-Myc, p53,mechanistic target of rapamycin complex (mTORC1), polycombcomplex protein (Bmi-1), Notch,Nanog,Tie-2, Oct-4,CD59, p53, CD34, B-cell lymphoma-2 (Bcl2),sterol regulatory element-binding protein2 (SREBP2), peroxisome proliferator-activated receptor gamma (PPARγ) nuclear respiratory factor 1 (NRF1), mitochondrial transcription factor A (Tfam), peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α) within miR-2909 expression vector transfected human PBMCs as well as PBMCs transfected with control vector containing scrambled sequence after 48h post-transfection using RT-qPCR and cellular ultrastructural features induced by miR-2909 ectopic expression were observed using transmission electron microscopy and morphometric analysis of an electron micrograph.

RESULTS

Ectopic expression of miR-2909 within human PBMCs resulted in their reprogramming into stem-like phenotype indicated by mitochondrial globular shaped coupled with cristae-poor morphology. Nuclear to cytoplasmic ratio (N/C), quantification of ATP levels, GSSG/GSH ratio, mitochondrial cytochrome c oxidase activity, secreted lactate concentrations, activity of antioxidant enzymes, levels of esterified cholesterol and triglycerides and flow-cytometric detection of apoptosis confirmed the compromised nature of mitochondrial function induced by ectopic miR-2909 expression in human PBMCs.

CONCLUSION

Based upon these results we propose that AATF gene-encoded miR-2909 may act as an epigenetic switch for cellular aerobic-glycolysis to ensure de-differentiation.

Chemically induced degradation of CK2 by proteolysis targeting chimeras based on a ubiquitin-proteasome pathway

As a ubiquitous, highly pleiotropic and constitutively active serine/threonine protein kinase, casein kinase 2 (CK2) is closely associated with tumorigenesis by its overexpression in cancer cells. Here we report several proteolysis targeting chimeras (PROTACs) via "click reaction" to connect a CK2 inhibitor (CX-4945) and pomalidomide for degradation of CK2 protein. Among them, compound 2 degraded CK2 in a dose and time-dependent manner, and kept CK2 at a low basal level by recruiting ubiquitin-proteasome system. The degradation of CK2 resulted in the reduced phosphorylation of Akt and the up-regulation of p53. As a CK2 protein degrader, 2 showed the analogous cytotoxicity to CX-4945 but with a quite different mechanism of action from the CK2 inhibitor, hinting that degradation of CK2 proteins by PROTACs is a potential way for cancer treatments.

p53 in AgRP neurons is required for protection against diet-induced obesity via JNK1

p53 is a well-known tumor suppressor that has emerged as an important player in energy balance. However, its metabolic role in the hypothalamus remains unknown. Herein, we show that mice lacking p53 in agouti-related peptide (AgRP), but not proopiomelanocortin (POMC) or steroidogenic factor-1 (SF1) neurons, are more prone to develop diet-induced obesity and show reduced brown adipose tissue (BAT) thermogenic activity. AgRP-specific ablation of p53 resulted in increased hypothalamic c-Jun N-terminal kinase (JNK) activity before the mice developed obesity, and central inhibition of JNK reversed the obese phenotype of these mice. The overexpression of p53 in the ARC or specifically in AgRP neurons of obese mice decreased body weight and stimulated BAT thermogenesis, resulting in body weight loss. Finally, p53 in AgRP neurons regulates the ghrelin-induced food intake and body weight. Overall, our findings provide evidence that p53 in AgRP neurons is required for normal adaptations against diet-induced obesity.

Emerging studies suggest that p53 is an important regulator of energy metabolism, yet there is little known about the metabolic function of this tumor suppressor in the hypothalamus. Here, authors illustrate that p53, specifically in AgRP neurons, is required for adaptation to diet-induced obesity.

Tailoring Chemotherapy for the African-Centric S47 Variant of TP53

The tumor suppressor TP53 is the most frequently mutated gene in human cancer and serves to restrict tumor initiation and progression. Single-nucleotide polymorphisms (SNP) in TP53 and p53 pathway genes can have a marked impact on p53 tumor suppressor function, and some have been associated with increased cancer risk and impaired response to therapy. Approximately 6% of Africans and 1% of African Americans express a p53 allele with a serine instead of proline at position 47 (Pro47Ser). This SNP impairs p53-mediated apoptosis in response to radiation and genotoxic agents and is associated with increased cancer risk in humans and in a mouse model. In this study, we compared the ability of wild-type (WT) and S47 p53 to suppress tumor development and respond to therapy. Our goal was to find therapeutic compounds that are more, not less, efficacious in S47 tumors. We identified the superior efficacy of two agents, cisplatin and BET inhibitors, on S47 tumors compared with WT. Cisplatin caused dramatic decreases in the progression of S47 tumors by activating the p53/PIN1 axis to drive the mitochondrial cell death program. These findings serve as important proof of principle that chemotherapy can be tailored to p53 genotype.Significance: A rare African-derived radioresistant p53 SNP provides proof of principle that chemotherapy can be tailored to TP53 genotype. Cancer Res; 78(19); 5694-705. ©2018 AACR.

Microenvironmental regulation of cancer cell metabolism: implications for experimental design and translational studies

Cancers have an altered metabolism, and there is interest in understanding precisely how oncogenic transformation alters cellular metabolism and how these metabolic alterations can translate into therapeutic opportunities. Researchers are developing increasingly powerful experimental techniques to study cellular metabolism, and these techniques have allowed for the analysis of cancer cell metabolism, both in tumors and in ex vivo cancer models. These analyses show that, while factors intrinsic to cancer cells such as oncogenic mutations, alter cellular metabolism, cell-extrinsic microenvironmental factors also substantially contribute to the metabolic phenotype of cancer cells. These findings highlight that microenvironmental factors within the tumor, such as nutrient availability, physical properties of the extracellular matrix, and interactions with stromal cells, can influence the metabolic phenotype of cancer cells and might ultimately dictate the response to metabolically targeted therapies. In an effort to better understand and target cancer metabolism, this Review focuses on the experimental evidence that microenvironmental factors regulate tumor metabolism, and on the implications of these findings for choosing appropriate model systems and experimental approaches.

Protective role of fenofibrate in sepsis-induced acute kidney injury in BALB/c mice

Acute kidney injury (AKI) is a severe complication of sepsis, which largely contributes to the associated high mortality rate. Fenofibrate, a peroxisome proliferator activated receptor α (PPARα) agonist, has received considerable attention because of its effects related to renal damage-related energy metabolism and inflammation. The present study investigated the effects of fenofibrate on sepsis-associated AKI in BALB/c mice subjected to caecal ligation and puncture (CLP). Eight-week-old male BALB/c mice were divided into four groups: control group, fenofibrate group, caecal ligation and puncture (CLP) group, and fenofibrate + CLP group. CLP was performed after mice were gavaged with fenofibrate for 2 weeks. After 48 hours, we measured the histopathological alterations of the kidney tissue and plasma levels of serum creatinine (CRE), neutrophil gelatinase-associated lipocalin (NGAL), reactive oxygen species (ROS), ATP, and ADP. We evaluated PPARα and P53 protein levels as well as interleukin (IL)-1β, IL-6, and tumour necrosis factor-α mRNA levels. Our results showed that administering fenofibrate significantly reduced kidney histological alterations caused by CLP. Fenofibrate inhibited the plasma levels of ROS, CRE, NGAL, and increased the ATP/ADP ratio. Fenofibrate significantly inhibited elevations in P53, IL-1β, IL-6, and tumour necrosis factor-α expression. The results suggest that fenofibrate administration effectively modulates energy metabolism and may be a novel approach to treat sepsis-induced renal damage.

Mitochondrial quality control in AMD: does mitophagy play a pivotal role?

Age-related macular degeneration (AMD) is the predominant cause of visual loss in old people in the developed world, whose incidence is increasing. This disease is caused by the decrease in macular function, due to the degeneration of retinal pigment epithelium (RPE) cells. The aged retina is characterised by increased levels of reactive oxygen species (ROS), impaired autophagy, and DNA damage that are linked to AMD pathogenesis. Mitophagy, a mitochondria-specific type of autophagy, is an essential part of mitochondrial quality control, the collective mechanism responsible for this organelle's homeostasis. The abundance of ROS, DNA damage, and the excessive energy consumption in the ageing retina all contribute to the degeneration of RPE cells and their mitochondria. We discuss the role of mitophagy in the cell and argue that its impairment may play a role in AMD pathogenesis. Thus, mitophagy as a potential therapeutic target in AMD and other degenerative diseases is as well explored.

p53-inducible DPYSL4 associates with mitochondrial supercomplexes and regulates energy metabolism in adipocytes and cancer cells

The tumor suppressor p53 regulates multiple cellular functions, including energy metabolism. Metabolic deregulation is implicated in the pathogenesis of some cancers and in metabolic disorders and may result from the inactivation of p53 functions. Using RNA sequencing and ChIP sequencing of cancer cells and preadipocytes, we demonstrate that p53 modulates several metabolic processes via the transactivation of energy metabolism genes including dihydropyrimidinase-like 4 (DPYSL4). DPYSL4 is a member of the collapsin response mediator protein family, which is involved in cancer invasion and progression. Intriguingly, DPYSL4 overexpression in cancer cells and preadipocytes up-regulated ATP production and oxygen consumption, while DPYSL4 knockdown using siRNA or CRISPR/Cas9 down-regulated energy production. Furthermore, DPYSL4 was associated with mitochondrial supercomplexes, and deletion of its dihydropyrimidinase-like domain abolished its association and its ability to stimulate ATP production and suppress the cancer cell invasion. Mouse-xenograft and lung-metastasis models indicated that DPYSL4 expression compromised tumor growth and metastasis in vivo. Consistently, database analyses demonstrated that low DPYSL4 expression was significantly associated with poor survival of breast and ovarian cancers in accordance with its reduced expression in certain types of cancer tissues. Moreover, immunohistochemical analysis using the adipose tissue of obese patients revealed that DPYSL4 expression was positively correlated with INFg and body mass index in accordance with p53 activation. Together, these results suggest that DPYSL4 plays a key role in the tumor-suppressor function of p53 by regulating oxidative phosphorylation and the cellular energy supply via its association with mitochondrial supercomplexes, possibly linking to the pathophysiology of both cancer and obesity.

Roles of microRNA in prostate cancer cell metabolism

MicroRNAs are non-coding RNA which functions as regulators of genes expression. MicroRNAs have shown their biological functions in cell proliferation, cell cycle, cell metabolism, apoptosis, invasion and metastasis. Cancer cells have the ability to grow in the absence of growth factors by increased metabolic activity. MicroRNAs regulate cell metabolic processes by targeting the key enzymes or transporters and change the metabolic activities by interfering with oncogenes/tumor suppressors, hypoxia, signalling pathways and cell adhesion. This review mainly explains the roles of microRNAs in prostate cancer cell metabolism, such as glucose uptake, glycolysis and lactate secretion, lipid metabolism and interaction with signalling pathways. The relation of microRNAs with hypoxia and cell adhesion in cell metabolism is also highlighted. Therefore, miRNAs help in regulating the metabolism of survived tumor cells, understanding such miRNA-mediated interaction could lead to new avenues in therapeutic application to treat PCa.

The p53 Family in Brain Disease

SIGNIFICANCE

The p53 family of transcription factors, including p53, p63, and p73, plays key roles in both biological and pathological processes, including cancer and neural development. Recent Advances: In recent years, a growing body of evidence has indicated that the entire p53 family is involved in the regulation of the central nervous system (CNS) functions as well as in the pathogenesis of several neurological disorders. Mechanistically, the p53 proteins control neuronal cell fate, terminal differentiation, and survival, via a complex interplay among the family members.

CRITICAL ISSUES

In this article, we discuss the involvement of the p53 family in neurobiology and in pathological conditions affecting the CNS, including neuroinflammation.

FUTURE DIRECTIONS

Understanding the molecular mechanism(s) underlying the function of the p53 family could improve our general knowledge of the pathogenesis of brain disorders and potentially pave the road for new therapeutic intervention. Antioxid. Redox Signal. 29, 1-14.

Role of p53 in the Regulation of the Inflammatory Tumor Microenvironment and Tumor Suppression

p53 has functional roles in tumor suppression as a guardian of the genome, surveillant of oncogenic cell transformation, and as recently demonstrated, a regulator of intracellular metabolism. Accumulating evidence has shown that the tumor microenvironment, accompanied by inflammation and tissue remodeling, is important for cancer proliferation, metastasis, and maintenance of cancer stem cells (CSCs) that self-renew and generate the diverse cells comprising the tumor. Furthermore, p53 has been demonstrated to inhibit inflammatory responses, and functional loss of p53 causes excessive inflammatory reactions. Moreover, the generation and maintenance of CSCs are supported by the inflammatory tumor microenvironment. Considering that the functions of p53 inhibit reprogramming of somatic cells to stem cells, p53 may have a major role in the inflammatory microenvironment as a tumor suppressor. Here, we review our current understanding of the mechanisms underlying the roles of p53 in regulation of the inflammatory microenvironment, tumor microenvironment, and tumor suppression.

Exhaled breath analysis for gastric cancer diagnosis in Colombian patients

We present here the first study that directly correlates gastric cancer (GC) with specific biomarkers in the exhaled breath composition on a South American population, which registers one of the highest global incidence rates of gastric affections. Moreover, we demonstrate a novel solid state sensor that predicts correct GC diagnosis with 97% accuracy. Alveolar breath samples of 30 volunteers (patients diagnosed with gastric cancer and a controls group formed of patients diagnosed with other gastric diseases) were collected and analyzed by gas-chromatography/mass-spectrometry (GC-MS) and with an innovative chemical gas sensor based on gold nanoparticles (AuNP) functionalized with octadecylamine ligands. Our GC-MS analyses identified 6 volatile organic compounds that showed statistically significant differences between the cancer patients and the controls group. These compounds were different from those identified in previous studied performed on other populations with high incidence rates of this malady, such as China (representative for Eastern Asia region) and Latvia (representative for Baltic States), attributable to lifestyle, alimentation and genetics differences. A classification model based on principal component analysis of our sensor data responses to the breath samples yielded 97% accuracy, 100% sensitivity and 93% specificity. Our results suggest a new and non-intrusive methodology for early diagnosis of gastric cancer that may be deployed in regions lacking well-developed health care systems as a prediagnosis test for selecting the patients that should undergo deeper investigations (e.g., endoscopy and biopsy).

The Roles of p53 in Mitochondrial Dynamics and Cancer Metabolism: The Pendulum between Survival and Death in Breast Cancer?

Cancer research has been heavily geared towards genomic events in the development and progression of cancer. In contrast, metabolic regulation, such as aberrant metabolism in cancer, is poorly understood. Alteration in cellular metabolism was once regarded simply as a consequence of cancer rather than as playing a primary role in cancer promotion and maintenance. Resurgence of cancer metabolism research has identified critical metabolic reprogramming events within biosynthetic and bioenergetic pathways needed to fulfill the requirements of cancer cell growth and maintenance. The tumor suppressor protein p53 is emerging as a key regulator of metabolic processes and metabolic reprogramming in cancer cells&mdash;balancing the pendulum between cell death and survival. This review provides an overview of the classical and emerging non-classical tumor suppressor roles of p53 in regulating mitochondrial dynamics: mitochondrial engagement in cell death processes in the prevention of cancer. On the other hand, we discuss p53 as a key metabolic switch in cellular function and survival. The focus is then on the conceivable roles of p53 in breast cancer metabolism. Understanding the metabolic functions of p53 within breast cancer metabolism will, in due course, reveal critical metabolic hotspots that cancers advantageously re-engineer for sustenance. Illustration of these events will pave the way for finding novel therapeutics that target cancer metabolism and serve to overcome the breast cancer burden.

Illicit drug ketamine induces adverse effects from behavioral alterations and oxidative stress to p53-regulated apoptosis in medaka fish under environmentally relevant exposures

With increasing problems of drug abuse worldwide, aquatic ecosystems are contaminated by human pharmaceuticals from the discharge of hospital or municipal effluent. However, ecotoxicity data and related toxic mechanism for neuroactive controlled or illicit drugs are still lacking, so assessing the associated hazardous risk is difficult. This study aims to investigate the behavioral changes, oxidative stress, gene expression and neurotoxic or apoptosis effect(s) in larvae of medaka fish (Oryzias latipes) with environmentally relevant exposures of ketamine (KET) solutions for 1-14 days. KET exposure at an environmentally relevant concentration (0.004 μM) to 40 μM conferred specific patterns in larval swimming behavior during 24 h. At 14 days, such exposure induced dose- and/or time-dependent alteration on reactive oxygen species induction, the activity of antioxidants catalase and superoxide dismutase, glutathione S-transferase and malondialdehyde contents in fish bodies. KET-induced oxidative stress disrupted the expression of acetylcholinesterase and p53-regulated apoptosis pathways and increased caspase expression in medaka larvae. The toxic responses of medaka larvae, in terms of chemical effects, were qualitatively analogous to those of zebrafish and mammals. Our results implicate a toxicological impact of waterborne KET on fish development and human health, for potential ecological risks of directly releasing neuroactive drugs-containing wastewater into the aquatic environment.

Good Guy or Bad Guy? The Duality of Wild-Type p53 in Hormone-Dependent Breast Cancer Origin, Treatment, and Recurrence

"Lactation is at one point perilously near becoming a cancerous process if it is at all arrested", Beatson, 1896. Most breast cancers arise from the milk-producing cells that are characterized by aberrant cellular, molecular, and epigenetic translation. By understanding the underlying molecular disruptions leading to the origin of cancer, we might be able to design novel strategies for more efficacious treatments or, ambitiously, divert the cancerous process. It is an established reality that full-term pregnancy in a young woman provides a lifetime reduction in breast cancer risk, whereas delay in full-term pregnancy increases short-term breast cancer risk and the probability of latent breast cancer development. Hormonal activation of the p53 protein (encode by the TP53 gene) in the mammary gland at a critical time in pregnancy has been identified as one of the most important determinants of whether the mammary gland develops latent breast cancer. This review discusses what is known about the protective influence of female hormones in young parous women, with a specific focus on the opportune role of wild-type p53 reprogramming in mammary cell differentiation. The importance of p53 as a protector or perpetrator in hormone-dependent breast cancer, resistance to treatment, and recurrence is also explored.