Regulation Of Cancer Cell Metabolism Research Articles

Integrative analysis of mitochondrial metabolic reprogramming in early-stage colon and liver cancer.

Gastrointestinal malignancies, including colon adenocarcinoma (COAD) and liver hepatocellular carcinoma (LIHC), remain leading causes of cancer-related deaths worldwide. To better understand the underlying mechanisms of these cancers and identify potential therapeutic targets, we analyzed publicly accessible Cancer Genome Atlas datasets of COAD and LIHC. Our analysis revealed that differentially expressed genes (DEGs) during early tumorigenesis were associated with cell cycle regulation. Additionally, genes related to lipid metabolism were significantly enriched in both COAD and LIHC, suggesting a crucial role for dysregulated lipid metabolism in their development and progression. We also identified a subset of DEGs associated with mitochondrial function and structure, including upregulated genes involved in mitochondrial protein import and respiratory complex assembly. Further, we identified mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase (HMGCS2) as a crucial regulator of cancer cell metabolism. Using a genome-scale metabolic model, we demonstrated that HMGCS2 suppression increased glycolysis, lipid biosynthesis, and elongation while decreasing fatty acid oxidation in colon cancer cells. Our study highlights the potential contribution of dysregulated lipid metabolism, including ketogenesis, to COAD and LIHC development and progression and identifies potential therapeutic targets for these malignancies.

Cytosolic and mitochondrial translation elongation are coordinated through the molecular chaperone TRAP1 for the synthesis and import of mitochondrial proteins.

A complex interplay between mRNA translation and cellular respiration has been recently unveiled, but its regulation in humans is poorly characterized in either health or disease. Cancer cells radically reshape both biosynthetic and bioenergetic pathways to sustain their aberrant growth rates. In this regard, we have shown that the molecular chaperone TRAP1 not only regulates the activity of respiratory complexes, behaving alternatively as an oncogene or a tumor suppressor, but also plays a concomitant moonlighting function in mRNA translation regulation. Herein, we identify the molecular mechanisms involved, showing that TRAP1 (1) binds both mitochondrial and cytosolic ribosomes, as well as translation elongation factors; (2) slows down translation elongation rate; and (3) favors localized translation in the proximity of mitochondria. We also provide evidence that TRAP1 is coexpressed in human tissues with the mitochondrial translational machinery, which is responsible for the synthesis of respiratory complex proteins. Altogether, our results show an unprecedented level of complexity in the regulation of cancer cell metabolism, strongly suggesting the existence of a tight feedback loop between protein synthesis and energy metabolism, based on the demonstration that a single molecular chaperone plays a role in both mitochondrial and cytosolic translation, as well as in mitochondrial respiration.

Study on the Intervention Mechanism of Cryptotanshinone on Human A2780 Ovarian Cancer Cell Line Using GC-MS-Based Cellular Metabolomics.

Cryptotanshinone (CT), an active component of the traditional Chinese medicine Salvia miltiorrhiza Bunge, exhibits a wide range of biological and pharmacological activities. Although the anticancer activity of CT is well known, the knowledge of its effect on the regulation of cancer cell metabolism is relatively new. The present study investigated the anticancer mechanism of CT in ovarian cancer with a focus on cancer metabolism. CCK8 assays, apoptosis assays, and cell cycle assays were conducted to reveal the growth-suppressive effect of CT on ovarian cancer A2780 cells. To explore the potential underlying mechanisms of CT, the changes in endogenous metabolites in A2780 cells before and after CT intervention were investigated using the gas chromatography-mass spectrometry (GC-MS) approach. A total of 28 important potential biomarkers underwent significant changes, mainly involving aminoacyl-tRNA biosynthesis, energy metabolism, and other pathways. Changes in the ATP and amino acid contents were verified with in vitro and in vivo experiments. Our results indicate that CT may exert an anti-ovarian cancer effect by inhibiting ATP production, promoting the protein catabolic process, and inhibiting protein synthesis, which may lead to cell cycle arrest and apoptosis.

Abstract 3704: The essential role of an alternate mRNA translation initiation in the regulation of breast cancer cell metabolism

Abstract Translational control and metabolic reprogramming are hallmarks of advanced cancers. Important genes involved in cancer progression express mRNAs that are selectively translated, including regulators of cancer cell metabolism. Cancer cells acquire an altered metabolism, switching from oxidative phosphorylation (OXPHOS) to a glycolytic phenotype (Warburg effect), to increase reliance on alternate metabolic pathways to support growth, proliferation, and metastasis. Triple-negative breast cancer (TNBC), one of the most aggressive and highly metastatic subtypes with the poorest outcome, is characterized by elevated glycolysis and low OXPHOS. Still, the exact mechanism for this metabolic switch is largely unknown. Using a TNBC cell model it has been shown an alternate mechanism of cap-dependent but mTORC1/eIF4Eindependent mRNA translation by the eIF4G homolog, DAP5, which directly binds the cap-binding protein eIF3d. Our research indicates that this alternate translation initiation is essential in regulating several mRNAs involved in breast cancer metabolism. DAVID analysis from genome-wide transcriptomic and translatomic studies, metabolomic assays including Glycolysis Assay [Extracellular Acidification], Oxidative Phosphorylation, and Mitotracker Assay, as well as RT-PCR and western blot analysis was performed from well-characterized triple-negative aggressive breast cancer cell lines,4T1 and MDA-231, Non-silencing (Nsi) control and silencing DAP5 (shDAP5) samples. Several mRNAs related to glucose metabolism decreased after silencing DAP5 and on the opposite, critical mRNAs associated with OXPHOS increased, independent of their steady-state mRNA abundance. Silencing DAP5 increased Oxidative Phosphorylation activity and decrease the glycolytic rate in TNBC breast cancer cells. Proteins correlated with aberrant glycolytic metabolism including the E-cadherin transcriptional repressors Snail (SNAI1) were reduced after silencing of DAP5. Our data indicates that the alternate mRNA translation initiation mechanism by DAP5 of specific mRNAs correlated to glycolysis and OXPHOS could play an essential role in the mechanism by which TNBC breast cancer cells orchestrate a metabolic switch required for malignant progression and metastasis. Citation Format: Hanna Rosenstock, Erna Mitaishvili, Columba de la Parra. The essential role of an alternate mRNA translation initiation in the regulation of breast cancer cell metabolism. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3704.

Abstract 5129: Neutrophil extracellular traps induced by surgical stress regulate cancer metabolism leading to tumor growth

Abstract Introduction: Surgery is a crucial intervention to cure malignancies. However, evidence shows that the surgical insult and its accompanying immune response can enhance tumor growth and metastasis. Neutrophil Extracellular Traps (NETs) released systemically during surgical stress were previously shown to contribute to this process. In fact, to generate increased energy demands required for growth and metastasis, cancer cells in a stressful microenvironment need an adaptive mechanism where metabolic reprogramming to fatty acid (FA) oxidation has been emerging as an important process. Here, we aim to explore the direct effects of surgical NETs in regulating cancer cell metabolism leading to tumor growth and metastasis. Methods: For the indolent tumor model, C57BL/6 mice were injected with a small number of LLC-1 (Lewis Lung Cancer-1) cells subcutaneously (SQ) and a group was subjected to laparotomy for 30 mins, with or without intraperitoneal DNAse (NET inhibitor) injection perioperatively. Tumor growth was then followed for 4 weeks. For the tumor metastasis model, LLC-1 cells were injected SQ and allowed to grow for 3 weeks before resection with or without perioperative DNAse. Tumor metastasis to the lungs was assessed after 3 weeks. In vitro experiments on LLC-1 and MC-38 (murine colon adenocarcinoma) cancer cells were performed using NETs released from neutrophils freshly isolated from mice bone marrow and stimulated with Phorbol myristate acetate (PMA). Results: For the indolent tumor model, injection of cancer cells did not lead to any significant tumor growth after 4 weeks unless mice underwent surgical stress via laparotomy. Treatment with DNAse significantly reversed their growth. For the tumor metastasis model, tumor resection alone led to significant lung metastasis, but DNAse treatment during resection or resection in PAD-4 KO mice (unable to form NETs) led to significantly less metastatic burden. Furthermore, in vitro treatment of cancer cells with NETs lead to significant cell proliferation, relatively more under hypoxic and serum conditions. This was paralleled with a significant increase in fluorescently labeled FA uptake into cancer cells as detected by flow cytometry, as well as a significant upregulation of gene expression of FA transport proteins and oxidation enzymes. Conclusion: Surgical stress can promote tumor growth and metastasis through cancer cell metabolic reprogramming induced by systemically released NETs. We hope that elucidating the molecular mechanism behind this process can help in finding therapeutics to prevent the protumorigenic effects of surgical stress. Citation Format: Tony Haykal, Ruiqi Yang, Celine Tohme, Ronghua Wang, David Geller, Christof Kaltenmeier, Hamza Yazdani, Samer Tohme. Neutrophil extracellular traps induced by surgical stress regulate cancer metabolism leading to tumor growth. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5129.

Fundamental Role of Pentose Phosphate Pathway within the Endoplasmic Reticulum in Glutamine Addiction of Triple-Negative Breast Cancer Cells.

Cancer utilization of large glutamine equivalents contributes to diverging glucose-6-P flux toward the pentose phosphate shunt (PPP) to feed the building blocks and the antioxidant responses of rapidly proliferating cells. In addition to the well-acknowledged cytosolic pathway, cancer cells also run a largely independent PPP, triggered by hexose-6P-dehydrogenase within the endoplasmic reticulum (ER), whose activity is mandatory for the integrity of ER-mitochondria networking. To verify whether this reticular metabolism is dependent on glutamine levels, we complemented the metabolomic characterization of intermediates of the glucose metabolism and tricarboxylic acid cycle with the estimation of proliferating activity, energy metabolism, redox damage, and mitochondrial function in two breast cancer cell lines. ER-PPP activity and its determinants were estimated by the ER accumulation of glucose analogs. Glutamine shortage decreased the proliferation rate despite increased ATP and NADH levels. It depleted NADPH reductive power and increased malondialdehyde content despite a marked increase in glucose-6P-dehydrogenase. This paradox was explained by the deceleration of ER-PPP favored by the decrease in hexose-6P-dehydrogenase expression coupled with the opposite response of its competitor enzyme glucose-6P-phosphatase. The decreased ER-PPP activity eventually hampered mitochondrial function and calcium exchanges. These data configure the ER-PPP as a powerful, unrecognized regulator of cancer cell metabolism and proliferation.

Regulation of mitochondrial complex III activity and assembly by TRAP1 in cancer cells

BackgroundMetabolic reprogramming is an important issue in tumor biology. A recently-identified actor in this regard is the molecular chaperone TRAP1, that is considered an oncogene in several cancers for its high expression but an oncosuppressor in others with predominant oxidative metabolism. TRAP1 is mainly localized in mitochondria, where it interacts with respiratory complexes, although alternative localizations have been described, particularly on the endoplasmic reticulum, where it interacts with the translational machinery with relevant roles in protein synthesis regulation.ResultsHerein we show that, inside mitochondria, TRAP1 binds the complex III core component UQCRC2 and regulates complex III activity. This decreases respiration rate during basal conditions but allows sustained oxidative phosphorylation when glucose is limiting, a condition in which the direct TRAP1-UQCRC2 binding is disrupted, but not TRAP1-complex III binding. Interestingly, several complex III components and assembly factors show an inverse correlation with survival and response to platinum-based therapy in high grade serous ovarian cancers, where TRAP1 inversely correlates with stage and grade and directly correlates with survival. Accordingly, drug-resistant ovarian cancer cells show high levels of complex III components and high sensitivity to complex III inhibitory drug antimycin A.ConclusionsThese results shed new light on the molecular mechanisms involved in TRAP1-dependent regulation of cancer cell metabolism and point out a potential novel target for metabolic therapy in ovarian cancer.

Targeted inhibition of ubiquitin signaling reverses metabolic reprogramming and suppresses glioblastoma growth

Glioblastoma multiforme (GBM) is the most frequent and aggressive form of primary brain tumor in the adult population; its high recurrence rate and resistance to current therapeutics urgently demand a better therapy. Regulation of protein stability by the ubiquitin proteasome system (UPS) represents an important control mechanism of cell growth. UPS deregulation is mechanistically linked to the development and progression of a variety of human cancers, including GBM. Thus, the UPS represents a potentially valuable target for GBM treatment. Using an integrated approach that includes proteomics, transcriptomics and metabolic profiling, we identify praja2, a RING E3 ubiquitin ligase, as the key component of a signaling network that regulates GBM cell growth and metabolism. Praja2 is preferentially expressed in primary GBM lesions expressing the wild-type isocitrate dehydrogenase 1 gene (IDH1). Mechanistically, we found that praja2 ubiquitylates and degrades the kinase suppressor of Ras 2 (KSR2). As a consequence, praja2 restrains the activity of downstream AMP-dependent protein kinase in GBM cells and attenuates the oxidative metabolism. Delivery in the brain of siRNA targeting praja2 by transferrin-targeted self-assembling nanoparticles (SANPs) prevented KSR2 degradation and inhibited GBM growth, reducing the size of the tumor and prolonging the survival rate of treated mice. These data identify praja2 as an essential regulator of cancer cell metabolism, and as a potential therapeutic target to suppress GBM growth.

Abstract 162: Identification of novel targets of Serine/arginine-rich protein-specific kinase 2

Abstract Altered metabolism is one of the hallmarks of cancer cells, supporting aberrant proliferation and survival in nutrient scarce and stressful environments. The reprogrammed metabolism supports the acquisition of malignant traits, increasing cellular fitness and providing a selective advantage in tumorigenesis. Multiple signaling cascades converge to regulate cancer cell metabolism to maintain a delicate balance between anabolic and catabolic processes, with the overall goal to fuel ATP production, biosynthesis of macromolecules and maintaining redox balance. Specifically, 70% of human cancers have hyperactivated mechanistic target of rapamycin (mTOR) signaling, the master regulator of cellular metabolism. As an important signaling node, mTOR complex 1(mTORC1) integrates upstream stimuli such as growth factors, amino acids and oxygen levels to regulate a myriad of anabolic processes including protein and nucleotide synthesis, RNA biogenesis and lipid metabolism, thereby promoting cell growth. The highly proliferative state of cancer cells, coupled with a change in energy demands, forces these cells to rewire their cellular metabolism to increase production of cellular building blocks like proteins, lipids and nucleotides. De novo lipogenesis provides lipids which act as an integral component of the plasma membrane as well as functioning as signaling molecules. In addition to promoting various anabolic processes, our lab has demonstrated that mTORC1-activated serine/arginine-rich protein-specific kinase 2 (SRPK2) phosphorylates splicing factors that stabilize lipogenic transcripts, protecting them from nonsense-mediated decay and thereby increasing de novo lipogenesis. This is in contrast to another serine/arginine-rich protein-specific kinase 1 (SRPK1), which is not regulated by mTORC1. Inhibition of the mTORC1-SRPK2 signaling axis blunts de novo lipogenesis and impedes tumor growth in several tumor xenograft models. SRPK2 overexpression is also observed in lung and colon cancers, suggesting SRPK2 may promote the growth of some human tumors. Despite the emerging role for SRPK2 in tumor growth, very few substrates of this kinase are known. We conducted a phospho-proteomics screen to identify novel substrates of SRPK1 and SRPK2. While some of the targets we identified are regulated in an mTORC1-dependent manner, many appear to be regulated independent of mTORC1, such as PTP1B, EGLN1 and EI24. We hypothesize that these mTORC1-independent targets could be SRPK1-dependent revealing potential distinct branches of SRPK signaling. Future studies will focus on not only validating a subset of these novel targets and their role in tumor growth, but also on exploring mTORC1-dependent and independent SRPK signaling. Citation Format: Kripa Shobana Ganesh, Bethany Schaffer, Gina Lee, Jared Johnson, Tomer M. Yaron, Noah Dephoure, Lewis C. Cantley, John Blenis. Identification of novel targets of Serine/arginine-rich protein-specific kinase 2 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 162.

Cellular experiments to study the inhibition of c-Myc/MAX heterodimerization.

The c-Myc oncogene is a master regulator of cancer cell metabolism, which controls a variety of pathways, including cell proliferation, cell cycle, apoptosis, and epigenetics. Belonging to the bHLH family of transcription factors, c-Myc forms a heterodimeric complex with another bHLH family protein MAX. c-Myc deregulation is reported in most cancers. This heterodimeric complex is a potent transcription factor that controls the expression of the target gene by binding to the E-box sequence and thereby controlling cancer cell proliferation. c-Myc in isolation has a partially folded structure and cannot carry the transcription. However, its heterodimerization provides the ability to bind DNA and carry out the regulatory function. Therefore, heterodimerization of c-Myc and Max is of great interest for cancers, and it has always been considered a target for cancer therapy. This book chapter will present a detailed protocol of cellular experiments employed to validate the in vitro potency of c-Myc inhibitor candidates to search for a novel c-Myc-targeted neoplastic drug.

Inhibition of Metabolism as a Therapeutic Option for Tamoxifen-Resistant Breast Cancer Cells

Cancer cells have an increased need for glucose and, despite aerobic conditions, obtain their energy through aerobic oxidation and lactate fermentation, instead of aerobic oxidation alone. Glutamine is an essential amino acid in the human body. Glutaminolysis and glycolysis are crucial for cancer cell survival. In the therapy of estrogen receptor α (ERα)-positive breast cancer (BC), the focus lies on hormone sensitivity targeting therapy with selective estrogen receptor modulators (SERMs) such as 4-hydroxytamoxifen (4-OHT), although this therapy is partially limited by the development of resistance. Therefore, further targets for therapy improvement of ERα-positive BC with secondary 4-OHT resistance are needed. Hence, increased glucose requirement and upregulated glutaminolysis in BC cells could be used. We have established sublines of ERα-positive MCF7 and T47D BC cells, which were developed to be resistant to 4-OHT. Further, glycolysis inhibitor 2-Deoxy-D-Glucose (2-DG) and glutaminase inhibitor CB-839 were analyzed. Co-treatments using 4-OHT and CB-839, 2-DG and CB-839, or 4-OHT, 2-DG and CB-839, respectively, showed significantly stronger inhibitory effects on viability compared to single treatments. It could be shown that tamoxifen-resistant BC cell lines, compared to the non-resistant cell lines, exhibited a stronger reducing effect on cell viability under co-treatments. In addition, the tamoxifen-resistant BC cell lines showed increased expression of proto-oncogene c-Myc compared to the parental cell lines. This could be reduced depending on the treatment. Suppression of c-Myc expression using specific siRNA completely abolished resistance to 4OH-tamoxifen. In summary, our data suggest that combined treatments affecting the metabolism of BC are suitable depending on the cellularity and resistance status. In addition, the anti-metabolic treatments affected the expression of the proto-oncogene c-Myc, a key player in the regulation of cancer cell metabolism.

Bromodomain Inhibition Is Effective Against Acute Myeloid Leukemia Cells Under Hypoxia and Induces Genome-Dependent Metabolic Perturbations

Inhibition of bromodomain-containing (BRD) proteins showed anti-tumor activity against different subtypes of acute myeloid leukemia (AML; Dawson et al. Nature 2011; Zuber et al. Nature 2011; Dawson et al. Leukemia 2013; Chen et al. Cancer Cell 2014; Gröschel et al. Cell 2014; Zhao et al. Cell Reports 2016). However, epigenetic and functional changes occurring under hypoxic conditions may affect BRD protein activity and the consequences of its inhibition. Moreover, the levels of c-MYC, a main target of bromodomain inhibitors, are decreased at low oxygen concentrations mimicking the bone marrow microenvironment which harbor leukemia stem cells, the final target of successful therapies.We treated AML cell lines representative of diverse genetic background (KG1; MLL-driven: MOLM-13, NOMO-1, NPM1 and DNMT3A mutated: OCI-AML3; t(8;21): Kasumi-1; c-MYC-amplified: HL-60) for 48h with the bromodomain inhibitor GSK1215101A (250 µM or 500 µM) under hypoxic conditions (1% O2). GSK1215101A reduced cell viability in a dose-dependent manner in all the cell lines (15%-35% reduction at 250 µM and 25%-65% reduction at 500 µM) except for HL60, with Kasumi-1 being the most sensitive model. A significant increase of Annexin V+ apoptotic cells was detected in NOMO-1 and Kasumi-1 cells, while OCI-AML3, Kasumi-1, HL-60 and KG-1 showed a marked decrease in cell proliferation with reduction of the percentage of cells in S phase and arrest into G0/G1 phase.To better understand GSK1215101A effects on AML cells, we performed gene expression profiling of actively translated mRNAs isolated by polysome profiling, along with western blot analysis of OCI-AML3, Kasumi-1 (drug-sensitive) and HL-60 (drug-resistant) cell lines after 16 hour of treatment (in order to allow cell adaption to the selective pressure induced by the drug, while avoiding massive cell death). GSK1215101A enforced hypoxia-induced c-MYC downregulation in all the cell lines and induced HIF-1a upregulation specifically in drug-sensitive ones, which was confirmed by immuofluorescence.Moreover, since c-MYC is a known regulator of cancer cell metabolism, we analyzed the metabolic changes induced by GSK1215101A by Ultrahigh Performance Liquid Chromatography-Tandem Mass Spectroscopy (Metabolon, Inc). GSK1215101A treatment resulted in changes in metabolite levels that are consistent with alterations in energy metabolism and cell component biosynthesis, with marked differences between the OCI-AML3 and Kasumi-1 models. Lactate levels were significantly reduced in hypoxic Kasumi-1 cells after treatment, which may be consistent with a drug-dependent decrease in lactate dehydrogenase activity, while no differences were observed at transcriptional and translational level. Little effects were observed on OCI-AML3 lactate levels. In parallel, OCI-AML3 showed a significant increase of both the reduced (3.9-fold) and oxidized (2.6-fold) forms of glutathione, which plays an important role in antioxidant defense, redox-homeostasis and protein folding. Consistently, the translational profile of OCI-AML3 cells showed enrichment of deregulated genes involved in superoxide metabolic process and response to oxidative stress (NCF1/2, ADNP2, XBP1, HSPA1A/B).Taken together, these data indicate that inhibition of bromodomain-containing proteins is effective against AML cells under hypoxic conditions and offer insights into the drug effects on leukemic cell metabolism, which is highly dependent on the genomic backgrounds. Moreover, the results suggest potential targets for novel combination therapies interfering with metabolic pathways or HIF-1a activity.Supported by: EHA research fellowship award, ELN, AIL, AIRC, project Regione-Università 2010-12 (L. Bolondi), FP7 NGS-PTL project, HARMONY project, Fondazione del Monte BO e RA project. DisclosuresMartinelli:ARIAD/INCYTE: Consultancy; PFIZER: Consultancy; ROCHE: Consultancy; JOHNSON & JOHNSON: Consultancy; CELGENE: Consultancy; AMGEN: Consultancy.

RB/E2F1 as a Master Regulator of Cancer Cell Metabolism in Advanced Disease.

Loss of the retinoblastoma (RB) tumor suppressor protein is a critical step in reprogramming biological networks that drive cancer progression, although mechanistic insight has been largely limited to the impact of RB loss on cell-cycle regulation. Here, isogenic modeling of RB loss identified disease stage-specific rewiring of E2F1 function, providing the first-in-field mapping of the E2F1 cistrome and transcriptome after RB loss across disease progression. Biochemical and functional assessment using both in vitro and in vivo models identified an unexpected, prominent role for E2F1 in regulation of redox metabolism after RB loss, driving an increase in the synthesis of the antioxidant glutathione, specific to advanced disease. These E2F1-dependent events resulted in protection from reactive oxygen species in response to therapeutic intervention. On balance, these findings reveal novel pathways through which RB loss promotes cancer progression and highlight potentially new nodes of intervention for treating RB-deficient cancers. SIGNIFICANCE: This study identifies stage-specific consequences of RB loss across cancer progression that have a direct impact on tumor response to clinically utilized therapeutics. The study herein is the first to investigate the effect of RB loss on global metabolic regulation and link RB/E2F1 to redox control in multiple advanced diseases.This article is highlighted in the In This Issue feature, p. 2113.

Phosphatase of regenerating liver-3 regulates cancer cell metabolism in multiple myeloma.

Cancer cells often depend on microenvironment signals from molecules such as cytokines for proliferation and metabolic adaptations. PRL-3, a cytokine-induced oncogenic phosphatase, is highly expressed in multiple myeloma cells and associated with poor outcome in this cancer. We studied whether PRL-3 influences metabolism. Cells transduced to express PRL-3 had higher aerobic glycolytic rate, oxidative phosphorylation, and ATP production than the control cells. PRL-3 promoted glucose uptake and lactate excretion, enhanced the levels of proteins regulating glycolysis and enzymes in the serine/glycine synthesis pathway, a side branch of glycolysis. Moreover, mRNAs for these proteins correlated with PRL-3 expression in primary patient myeloma cells. Glycine decarboxylase (GLDC) was the most significantly induced metabolism gene. Forced GLDC downregulation partly counteracted PRL-3-induced aerobic glycolysis, indicating GLDC involvement in a PRL-3-driven Warburg effect. AMPK, HIF-1α, and c-Myc, important metabolic regulators in cancer cells, were not mediators of PRL-3's metabolic effects. A phosphatase-dead PRL-3 mutant, C104S, promoted many of the metabolic changes induced by wild-type PRL-3, arguing that important metabolic effects of PRL-3 are independent of its phosphatase activity. Through this study, PRL-3 emerges as one of the key mediators of metabolic adaptations in multiple myeloma.

Metabolic reprogramming of cancer-associated fibroblasts and its effect on cancer cell reprogramming.

Cancer cells are well-known for adapting their metabolism to maintain high proliferation rates and survive in unfavorable environments with low oxygen and nutritional deficiency. Metabolic reprogramming most commonly arises from the tumor microenvironment (TME). The events of metabolic pathways include the Warburg effect, shift in Krebs cycle metabolites, and increase rate of oxidative phosphorylation that provides the energy for the development and invasion of cancer cells. The TME and shift in tumor metabolism shows a close relationship through bidirectional signaling pathways between the stromal and tumor cells. Cancer-associated fibroblasts (CAFs) are the main type of stromal cells in the TME and consist of a heterogeneous and plastic population that play key roles in tumor growth and metastatic capacity. Emerging evidence suggests that CAFs act as major regulators in shaping tumor metabolism especially through the dysregulation of several metabolic pathways, including glucose, amino acid, and lipid metabolism. The arrangement of these metabolic switches is believed to shape distinct CAF behavior and change tumor cell behavior by the CAFs. The crosstalk between cancer cells and CAFs is associated with cell metabolic reprogramming that contributes to cancer cell growth, progression, and evasion from cancer therapies. But the mechanism and process of this interaction remain unclear. This review aimed to highlight the metabolic couplings between tumor cells and CAFs. We reviewed the recent literature supporting an important role of CAFs in the regulation of cancer cell metabolism, and the relevant pathways, which may serve as targets for therapeutic interventions.

Cell metabolic profiling of colorectal cancer via 1H NMR

BackgroundProtein arginine methyltransferase 5 (PRMT5) belongs to a large family of protein arginine methyltransferases (PRMTs) that play essential role in gene transcription and regulate tumorigenesis. However, the role of PRMT5 in the regulation of cancer cell metabolism remains unclear. MethodsCell metabolomic analysis was performed on SW480 cells transfected with small interfering RNA (siRNA) specifically targeting PRMT5, followed by metabolomic pathway analysis. ResultsPRMT5 was overexpressed in colorectal cancer (CRC) tissues, and downregulation of PRMT5 suppressed CRC cell proliferation and the levels of PRMT5 and symmetric dimethylation of histone H3 (H3R8me2s). In addition, we found distinct differences in metabolite classification and function in PRMT5 knockdown SW480 cells compared to control SW480 cells. PRMT5 knockdown increased the levels of amino acids and carbohydrates, particularly related to the arginine metabolism such as glutamate, glutamine (Gln), proline, creatine, creatinine and phosphocreatine (PCr). ConclusionsThese findings revealed a key role for PRMT5 as a regulator of CRC cell metabolism to mediate arginine methylation in CRC cells.

Why Warburg Works: Lactate Controls Immune Evasion through GPR81

Lactate accumulation in tumors-a hallmark of the Warburg effect-has recently been shown to regulate cancer cell metabolism and survival through autocrine activation of GPR81. Now, Brown etal. (2020) demonstrate that lactate surprisingly also controls immune evasion through paracrine activation of GPR81 on stromal dendritic cells.

Cancer associated fibroblast FAK regulates malignant cell metabolism

Emerging evidence suggests that cancer cell metabolism can be regulated by cancer-associated fibroblasts (CAFs), but the mechanisms are poorly defined. Here we show that CAFs regulate malignant cell metabolism through pathways under the control of FAK. In breast and pancreatic cancer patients we find that low FAK expression, specifically in the stromal compartment, predicts reduced overall survival. In mice, depletion of FAK in a subpopulation of CAFs regulates paracrine signals that increase malignant cell glycolysis and tumour growth. Proteomic and phosphoproteomic analysis in our mouse model identifies metabolic alterations which are reflected at the transcriptomic level in patients with low stromal FAK. Mechanistically we demonstrate that FAK-depletion in CAFs increases chemokine production, which via CCR1/CCR2 on cancer cells, activate protein kinase A, leading to enhanced malignant cell glycolysis. Our data uncover mechanisms whereby stromal fibroblasts regulate cancer cell metabolism independent of genetic mutations in cancer cells.

Crosstalk Between ER Stress, Unfolded Protein Response (UPR) and Wnt Signaling Pathway in Cancer

Abstract: 1. Context Endoplasmic reticulum stress (ER stess) is associated with endoplasmic reticulum perturbation homeostasis. Prolonged ER stress conditions may induce cell death. Unfolded protein response (UPR) attempts to restore normal cell conditions. 2. Evidence Acquisition There now exists an emergent body of evidence identifying the WNT signaling network as a regulator of cancer cell metabolism. Given that existing findings show that the WNT pathway and ER stress regulates changes in metabolic activities of cancer cells suggesting these signaling pathways represent critical nodes in the regulation of central metabolism in tumors. 3. Results Findings suggest that the molecular cross-talks between hypoxic ER stress, Wnt/βcatenin signaling, may represent an important mechanism that enables some tumor subtypes to survival and grow in hypoxic conditions. 4. Conclusions The present article disuses differential effects of the activation of the three arms of UPR, namely endoplasmic reticulum kinase (PERK), activation transcription factor -6 (ATF-6), and inositol –requiring enzyme (IRE-1) on cancer. This review also highlights regulators and downstream effectors of Wnt cascade and addresses the increasingly apparent crosstalk of Wnt with other tumorigenic signaling pathways.

The synthetic oleanane triterpenoid CDDO-Me binds and inhibits pyruvate kinase M2.

The M2 isoform of the glycolytic enzyme pyruvate kinase (PKM2) is one of the key components in the Warburg effect, and an important regulator of cancer cell metabolism. Elevated PKM2 expression is a hallmark of numerous tumor types, making it a promising target for cancer therapy. Migration of H1299 lung tumor cells treated with synthetic oleanane triterpenoid derivatives CDDO-Me and CDDO-Im was monitored using scratch and transwell assays. Direct binding and inhibition of PKM2 activity by CDDO-Me was demonstrated by pull-down and activity assays. PKM2 localization in the absence and presence of CDDO-Me or CDDO-Im was determined by subcellular fractionation and immunofluorescence microscopy. Involvement of PKM2 in tumor cell migration was assessed using a stable PKM2 knockdown cell line. We demonstrate that migration of H1299 lung tumor cells is inhibited by CDDO-Me and CDDO-Im in scratch and transwell assays. CDDO-Me binds directly and specifically to recombinant PKM2, leading to a reduction of its catalytic activity. PKM2 knockdown cells exhibit significantly lower migration compared to control cells when subjected to glucose and oxygen deprivation, but not under regular conditions. The results suggest that PKM2 expression in a tumor-like environment contributes to cell migration, and that PKM2 activity can be down regulated by synthetic triterpenoid derivatives.