Cancer metabolism: current perspectives and future directions

Metabolic vulnerabilities in cancer: A new therapeutic strategy

Cancer metabolism is now a key area for therapeutic intervention, targeting unique metabolic reprogramming crucial for tumor growth and survival. This article reviews the therapeutic potential of addressing metabolic vulnerabilities through glycolysis and glutaminase inhibitors, which disrupt cancer cell metabolism. Challenges such as tumor heterogeneity and adaptive resistance are discussed, with strategies including personalized medicine and predictive biomarkers to enhance treatment efficacy. Additionally, integrating diet and lifestyle changes with metabolic targeting underscores a holistic approach to improving therapy outcomes. The article also examines the benefits of incorporating these strategies into standard care, highlighting the potential for more tailored, safer treatments. In conclusion, exploiting metabolic vulnerabilities promises a new era in oncology, positioning metabolic targeting at the forefront of personalized cancer therapy and transforming patient care.

Unraveling the intricate relationship between lipid metabolism and oncogenic signaling pathways

Lipids, the primary constituents of the cell membrane, play essential roles in nearly all cellular functions, such as cell-cell recognition, signaling transduction, and energy provision. Lipid metabolism is necessary for the maintenance of life since it regulates the balance between the processes of synthesis and breakdown. Increasing evidence suggests that cancer cells exhibit abnormal lipid metabolism, significantly affecting their malignant characteristics, including self-renewal, differentiation, invasion, metastasis, and drug sensitivity and resistance. Prominent oncogenic signaling pathways that modulate metabolic gene expression and elevate metabolic enzyme activity include phosphoinositide 3-kinase (PI3K)/AKT, MAPK, NF-kB, Wnt, Notch, and Hippo pathway. Conversely, when metabolic processes are not regulated, they can lead to malfunctions in cellular signal transduction pathways. This, in turn, enables uncontrolled cancer cell growth by providing the necessary energy, building blocks, and redox potentials. Therefore, targeting lipid metabolism-associated oncogenic signaling pathways could be an effective therapeutic approach to decrease cancer incidence and promote survival. This review sheds light on the interactions between lipid reprogramming and signaling pathways in cancer. Exploring lipid metabolism as a target could provide a promising approach for creating anticancer treatments by identifying metabolic inhibitors. Additionally, we have also provided an overview of the drugs targeting lipid metabolism in cancer in this review.

Star-PAP controls oncogene expression through primary miRNA 3'-end formation to regulate cellular proliferation and tumour formation

Star-PAP is a non-canonical poly(A) polymerase that is down regulated in breast cancer. While Star-PAP down regulation impairs target mRNA polyadenylation, paradoxically, we see up regulation of a large number of oncogenes on Star-PAP knockdown. Using two breast cancer cells (MCF7 with high Star-PAP, and MDA-MB-231 with negligible Star-PAP level), we discover that Star-PAP negatively regulates oncogene expression and subsequently cellular proliferation. This regulation is compromised with Star-PAP mutant of 3'-end processing function (serine 6 to alanine, S6A phospho-mutation). Concomitantly, xenograft mice model using MDA-MB-231 cells reveals a reduction in the tumour formation on ectopic Star-PAP expression that is ameliorated by S6A mutation. We find that Star-PAP control of target oncogene expression is independent of Star-PAP-mediated alternative polyadenylation or target mRNA 3'-end formation. We demonstrate that Star-PAP regulates target oncogenes through cellular miRNAs (miR-421, miR-335, miR-424, miR-543, miR-205, miR-34a, and miR-26a) that are down regulated in breast cancer. Analysis of various steps in miRNA biogenesis pathway reveals that Star-PAP regulates 3'-end formation and synthesis of primary miRNA (host) transcripts that is dependent on S6 phosphorylation thus controlling mature miRNA generation. Using mimics and inhibitors of two target miRNAs (miR-421 and miR-424) after Star-PAP depletion in MCF7 or ectopic expression in MDA-MB-231 cells, we demonstrate that Star-PAP controls oncogene expression and cellular proliferation through targeting miRNAs that regulates tumour formation. Our study establishes a novel mechanism of oncogene expression independent of alternative polyadenylation through Star-PAP-mediated miRNA host transcript polyadenylation that regulates breast cancer progression.

Targeting Dysregulated Lipid Metabolism in Cancer with Pharmacological Inhibitors

Metabolic plasticity is recognised as a hallmark of cancer cells, enabling adaptation to microenvironmental changes throughout tumour progression. A dysregulated lipid metabolism plays a pivotal role in promoting oncogenesis. Oncogenic signalling pathways, such as PI3K/AKT/mTOR, JAK/STAT, Hippo, and NF-kB, intersect with the lipid metabolism to drive tumour progression. Furthermore, altered lipid signalling in the tumour microenvironment contributes to immune dysfunction, exacerbating oncogenesis. This review examines the role of lipid metabolism in tumour initiation, invasion, metastasis, and cancer stem cell maintenance. We highlight cybernetic networks in lipid metabolism to uncover avenues for cancer diagnostics, prognostics, and therapeutics.

Reprogramming of glucose metabolism in virus infected cells

Viral infection is a kind of cellular stress that leads to the changes in cellular metabolism. Many metabolic pathways in a host cell such as glycolysis, amino acid and nucleotide synthesis are altered following virus infection. Both oncogenic and non-oncogenic viruses depend on host cell glycolysis for their survival and pathogenesis. Recent studies have shown that the rate of glycolysis plays an important role in oncolysis as well by oncolytic therapeutic viruses. During infection, viral proteins interact with various cellular glycolytic enzymes, and this interaction enhances the catalytic framework of the enzymes subsequently the glycolytic rate of the cell. Increased activity of glycolytic enzymes following their interaction with viral proteins is vital for replication and to counteract the inhibition of glycolysis caused by immune response. In this review, the importance of host cell glycolysis and the modulation of glycolysis by various viruses such as oncogenic, non-oncogenic and oncolytic viruses are presented.

Deciphering the Functional Status of Breast Cancers through the Analysis of Their Extracellular Vesicles

Breast cancer (BC) accounts for the highest incidence of tumor-related mortality among women worldwide, justifying the growing search for molecular tools for the early diagnosis and follow-up of BC patients under treatment. Circulating extracellular vesicles (EVs) are membranous nanocompartments produced by all human cells, including tumor cells. Since minimally invasive methods collect EVs, which represent reservoirs of signals for cell communication, these particles have attracted the interest of many researchers aiming to improve BC screening and treatment. Here, we analyzed the cargoes of BC-derived EVs, both proteins and nucleic acids, which yielded a comprehensive list of potential markers divided into four distinct categories, namely, (i) modulation of aggressiveness and growth; (ii) preparation of the pre-metastatic niche; (iii) epithelial-to-mesenchymal transition; and (iv) drug resistance phenotype, further classified according to their specificity and sensitivity as vesicular BC biomarkers. We discuss the therapeutic potential of and barriers to the clinical implementation of EV-based tests, including the heterogeneity of EVs and the available technologies for analyzing their content, to present a consistent, reproducible, and affordable set of markers for further evaluation.

Bioenergetic alteration in gastrointestinal cancers: The good, the bad and the ugly

Cancer cells exhibit metabolic reprogramming and bioenergetic alteration, utilizing glucose fermentation for energy production, known as the Warburg effect. However, there are a lack of comprehensive reviews summarizing the metabolic reprogramming, bioenergetic alteration, and their oncogenetic links in gastrointestinal (GI) cancers. Furthermore, the efficacy and treatment potential of emerging anticancer drugs targeting these alterations in GI cancers require further evaluation. This review highlights the interplay between aerobic glycolysis, the tricarboxylic acid (TCA) cycle, and oxidative phosphorylation (OXPHOS) in cancer cells, as well as hypotheses on the molecular mechanisms that trigger this alteration. The role of hypoxia-inducible transcription factors, tumor suppressors, and the oncogenetic link between hypoxia-related enzymes, bioenergetic changes, and GI cancer are also discussed. This review emphasizes the potential of targeting bioenergetic regulators for anti-cancer therapy, particularly for GI cancers. Emphasizing the potential of targeting bioenergetic regulators for GI cancer therapy, the review categorizes these regulators into aerobic glycolysis/ lactate biosynthesis/transportation and TCA cycle/coupled OXPHOS. We also detail various anti-cancer drugs and strategies that have produced pre-clinical and/or clinical evidence in treating GI cancers, as well as the challenges posed by these drugs. Here we highlight that understanding dysregulated cancer cell bioenergetics is critical for effective treatments, although the diverse metabolic patterns present challenges for targeted therapies. Further research is needed to comprehend the specific mechanisms of inhibiting bioenergetic enzymes, address side effects, and leverage high-throughput multi-omics and spatial omics to gain insights into cancer cell heterogeneity for targeted bioenergetic therapies.

Aspartoacylase promotes the process of tumour development and is associated with immune infiltrates in gastric cancer

BACKGROUND

Aspartoacylase (ASPA) is a gene that plays an important role in the metabolic reprogramming of cancer. However, the clinical relevance of ASPA in gastric cancer (GC) has not been demonstrated.

METHODS

The link between ASPA and the clinical features of GC was determined using two public genomic databases. The multivariate Cox proportional hazard model and generalised linear regression model were applied to examine whether the ASPA level is associated with the prognosis and other pathological factors. In addition, the role of specific genes in the infiltration of immune cells in the setting of GC was investigated using a further immunological database. The expression level of various proteins was detected using a western blotting assay. Transwell and methyl thiazolyl tetrazolium tests were applied for the detection of cellular invasion and proliferation, with small hairpin ribonucleic acid used to knockdown ASPA.

RESULTS

According to the multivariate Cox regression results, the down-regulated ASPA expression is a distinct prognostic factor. Furthermore, ASPA has significant positive correlations with the infiltration of immune cells in GC lesions. Compared to the non-cancer tissues, the GC tissues had a significantly lower level of ASPA expression (p < 0.05). Using knockdown and overexpression techniques, it was demonstrated that ASPA affects the capacity of cell lines for GC to both proliferate and invade.

CONCLUSION

Overall, ASPA could promote the occurrence and development of GC and presents a promising predictive biomarker for the disease since it is favourably connected with immune infiltrates and negatively correlated with prognosis.

RAS-targeted cancer therapy: Advances in drugging specific mutations

Rat sarcoma (RAS), as a frequently mutated oncogene, has been studied as an attractive target for treating RAS-driven cancers for over four decades. However, it is until the recent success of kirsten-RAS (KRAS)^G12C inhibitor that RAS gets rid of the title "undruggable". It is worth noting that the therapeutic effect of KRAS^G12C inhibitors on different RAS allelic mutations or even different cancers with KRAS^G12C varies significantly. Thus, deep understanding of the characteristics of each allelic RAS mutation will be a prerequisite for developing new RAS inhibitors. In this review, the structural and biochemical features of different RAS mutations are summarized and compared. Besides, the pathological characteristics and treatment responses of different cancers carrying RAS mutations are listed based on clinical reports. In addition, the development of RAS inhibitors, either direct or indirect, that target the downstream components in RAS pathway is summarized as well. Hopefully, this review will broaden our knowledge on RAS-targeting strategies and trigger more intensive studies on exploiting new RAS allele-specific inhibitors.

Metabolic codependencies in the tumor microenvironment and gastric cancer: Difficulties and opportunities

Oncogenesis and the development of tumors affect metabolism throughout the body. Metabolic reprogramming (also known as metabolic remodeling) is a feature of malignant tumors that is driven by oncogenic changes in the cancer cells themselves as well as by cytokines in the tumor microenvironment. These include endothelial cells, matrix fibroblasts, immune cells, and malignant tumor cells. The heterogeneity of mutant clones is affected by the actions of other cells in the tumor and by metabolites and cytokines in the microenvironment. Metabolism can also influence immune cell phenotype and function. Metabolic reprogramming of cancer cells is the result of a convergence of both internal and external signals. The basal metabolic state is maintained by internal signaling, while external signaling fine-tunes the metabolic process based on metabolite availability and cellular needs. This paper reviews the metabolic characteristics of gastric cancer, focusing on the intrinsic and extrinsic mechanisms that drive cancer metabolism in the tumor microenvironment, and interactions between tumor cell metabolic changes and microenvironment metabolic changes. This information will be helpful for the individualized metabolic treatment of gastric cancers.

mtUPR Modulation as a Therapeutic Target for Primary and Secondary Mitochondrial Diseases

Mitochondrial dysfunction is a key pathological event in many diseases. Its role in energy production, calcium homeostasis, apoptosis regulation, and reactive oxygen species (ROS) balance render mitochondria essential for cell survival and fitness. However, there are no effective treatments for most primary and secondary mitochondrial diseases to this day. Therefore, new therapeutic approaches, such as the modulation of the mitochondrial unfolded protein response (mtUPR), are being explored. mtUPRs englobe several compensatory processes related to proteostasis and antioxidant system mechanisms. mtUPR activation, through an overcompensation for mild intracellular stress, promotes cell homeostasis and improves lifespan and disease alterations in biological models of mitochondrial dysfunction in age-related diseases, cardiopathies, metabolic disorders, and primary mitochondrial diseases. Although mtUPR activation is a promising therapeutic option for many pathological conditions, its activation could promote tumor progression in cancer patients, and its overactivation could lead to non-desired side effects, such as the increased heteroplasmy of mitochondrial DNA mutations. In this review, we present the most recent data about mtUPR modulation as a therapeutic approach, its role in diseases, and its potential negative consequences in specific pathological situations.

Dual inhibition of CPT1A and G6PD suppresses glioblastoma tumorspheres

PURPOSE

Limited treatment options are currently available for glioblastoma (GBM), an extremely lethal type of brain cancer. For a variety of tumor types, bioenergetic deprivation through inhibition of cancer-specific metabolic pathways has proven to be an effective therapeutic strategy. Here, we evaluated the therapeutic effects and underlying mechanisms of dual inhibition of carnitine palmitoyltransferase 1A (CPT1A) and glucose-6-phosphate dehydrogenase (G6PD) critical for fatty acid oxidation (FAO) and the pentose phosphate pathway (PPP), respectively, against GBM tumorspheres (TSs).

METHODS

Therapeutic efficacy against GBM TSs was determined by assessing cell viability, neurosphere formation, and 3D invasion. Liquid chromatography-mass spectrometry (LC-MS) and RNA sequencing were employed for metabolite and gene expression profiling, respectively. Anticancer efficacy in vivo was examined using an orthotopic xenograft model.

RESULTS

CPT1A and G6PD were highly expressed in GBM tumor tissues. Notably, siRNA-mediated knockdown of both genes led to reduced viability, ATP levels, and expression of genes associated with stemness and invasiveness. Similar results were obtained upon combined treatment with etomoxir and dehydroepiandrosterone (DHEA). Transcriptome analyses further confirmed these results. Data from LC-MS analysis showed that this treatment regimen induced a considerable reduction in the levels of metabolites associated with the TCA cycle and PPP. Additionally, the combination of etomoxir and DHEA inhibited tumor growth and extended survival in orthotopic xenograft model mice.

CONCLUSION

Our collective findings support the utility of dual suppression of CPT1A and G6PD with selective inhibitors, etomoxir and DHEA, as an efficacious therapeutic approach for GBM.

Two-in-One Nanoparticle Formulation to Deliver a Tyrosine Kinase Inhibitor and microRNA for Targeting Metabolic Reprogramming and Mitochondrial Dysfunction in Gastric Cancer

Dysregulational EGFR, KRAS, and mTOR pathways cause metabolic reprogramming, leading to progression of gastric cancer. Afatinib (Afa) is a broad-spectrum tyrosine kinase inhibitor that reduces cancer growth by blocking the EGFR family. MicroRNA 125 (miR-125) reportedly diminishes EGFRs, glycolysis, and anti-apoptosis. Here, a one-shot formulation of miR-125 and Afa was presented for the first time. The formulation comprised solid lipid nanoparticles modified with mitochondrial targeting peptide and EGFR-directed ligand to suppress pan-ErbB-facilitated epithelial–mesenchymal transition and mTOR-mediated metabolism discoordination of glycolysis–glutaminolysis–lipids. Results showed that this cotreatment modulated numerous critical proteins, such as EGFR/HER2/HER3, Kras/ERK/Vimentin, and mTOR/HIF1-α/HK2/LDHA pathways of gastric adenocarcinoma AGS cells. The combinatorial therapy suppressed glutaminolysis, glycolysis, mitochondrial oxidative phosphorylation, and fatty acid synthesis. The cotreatment also notably decreased the levels of lactate, acetyl-CoA, and ATP. The active involvement of mitophagy supported the direction of promoting the apoptosis of AGS cells, which subsequently caused the breakdown of tumor-cell homeostasis and death. In vivo findings in AGS-bearing mice confirmed the superiority of the anti-tumor efficacy and safety of this combination nanomedicine over other formulations. This one-shot formulation disturbed the metabolic reprogramming; alleviated the “Warburg effect” of tumors; interrupted the supply of fatty acid, cholesterol, and triglyceride; and exacerbated the energy depletion in the tumor microenvironment, thereby inhibiting tumor proliferation and aggressiveness. Collectively, the results showed that the two-in-one nanoparticle formulation of miR-125 and Afa was a breakthrough in simplifying drug preparation and administration, as well as effectively inhibiting tumor progression through the versatile targeting of pan-ErbB- and mTOR-mediated mitochondrial dysfunction and dysregulated metabolism.

Development of a SERS based cancer diagnosis approach employing cryosectioned thyroid tissue samples on PDMS

An efficient SERS based novel analytical approach named Cryosectioned-PDMS was developed systematically and evaluated applying on 64 thyroid biopsy samples. To utilize thyroid biopsy samples, a 20-μl volume of h-AgNPs suspension was dropped on a 5-μm thick cryosectioned biopsy specimen placed on the PDMS coated glass slide. The SERS spectra from a 10 × 10 points array acquired by mapping 22.5 μm × 22.5 μm sized area from suspended dried droplets placed on the tissue surface. The probability of correctly predicted performance for diagnosis of malignant, benign and healthy tissues was resulted in the accuracy of 100 % for the spectral bands at 667, 724, 920, 960, 1052, 1096, 1315 and 1457 cm^-1 using PCA-fed LDA machine learning. The Cryosectioned-PDMS biophotonic approach with PCA-LDA predictive model demonstrated that the vibrational signatures can accurately recognize the fingerprint of cancer pathology from a healthy one with a simple and fast sample preparation methodology.

Biochemical and Biological Evaluation of an L-Asparaginase from Isolated Escherichia coli MF-107 as an Anti-Tumor Enzyme on MCF7 Cell Line

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HIF1α/VEGF Feedback Loop Contributes to 5-Fluorouracil Resistance

5-Fluorouracil (5-Fu) is one of the basic drugs in colorectal cancer (CRC) chemotherapy, and its efficacy is mainly limited by the acquisition of drug resistance. However, the underlying mechanisms remain unclear. In this study, hypoxia inducible factor 1α (HIF1α) was screened for high expression in 5-Fu resistant HCT115 cells, which displayed epithelial–mesenchymal transition (EMT) phenotype. Suppression of HIF1α reversed EMT phenotype, reduced glucose transporter 1 (Glut1) expression, a key molecule mediated drug resistance. Moreover, we unveiled that vascular endothelial growth factor (VEGF) was regulated by HIF1α and mediated HIF1α-maintained malignant phenotype of 5-Fu resistant cells. Further studies verified that AKT/GSK3β signaling was activated in resistant cells and controlled HIF1α expression. Interestingly, we demonstrated that VEGF could feedback up-regulate HIF1α via AKT/GSK3β signaling. Clinically, HIF1α and VEGF were high expressed and associated with survival and prognosis in CRC patients. In conclusion, our findings proposed that HIF1α/VEGF feedback loop contributed to 5-Fu resistance, which might be potential therapeutic targets.

SETD5 Regulates Glycolysis in Breast Cancer Stem-Like Cells and Fuels Tumor Growth

Although glycolysis plays a pivotal role in breast cancer stem-like cell (BCSC) reprogramming, the molecular mechanisms that couple glycolysis to cancer stem-like cells remain unclear. SETD5 is a previously uncharacterized member of the histone lysine methyltransferase family. The goal of this study was to explore the mechanisms underlying the promotion of stem-like and glycolysis activation traits by SETD5. Previous studies have shown that overexpression of SETD5 in breast cancer tissues is associated positively with progression. The present study showed that SETD5 expression was enriched in BCSCs. Down-regulation of SETD5 significantly decreased BCSC properties and glycolysis in vitro and in vivo. Interestingly, SETD5 and glycolytic enzymes were accumulated in the central hypoxic regions of subcutaneous tumor tissues. Bioinformatic analysis predicted SETD5 binding to E1A binding protein p300 (EP300), and subsequently to hypoxia-inducible factor 1α (HIF-1α). The mechanistic study found that SETD5 is an upstream effector of EP300/HIF-1α. SETD5 knockdown reduced the expression of HIF-1α, hexokinase-2, and 6-phosphofructo-2-kinase in the nucleus after treatment with cobalt chloride, a chemical hypoxia mimetic agent that activates HIF-1α to accumulate in the nucleus. Therefore, SETD5 is required for glycolysis in BCSCs through binding to EP300/HIF-1α and could be a potential therapeutic target for breast cancer patients.

Double face of cytochrome c in cancers by Raman imaging

Cytochrome c (Cyt c) is a key protein that is needed to maintain life (respiration) and cell death (apoptosis). The dual-function of Cyt c comes from its capability to act as mitochondrial redox carrier that transfers electrons between the membrane-embedded complexes III and IV and to serve as a cytoplasmic apoptosis-triggering agent, activating the caspase cascade. However, the precise roles of Cyt c in mitochondria, cytoplasm and extracellular matrix under normal and pathological conditions are not completely understood. To date, no pathway of Cyt c release that results in caspase activation has been compellingly demonstrated in any invertebrate. The significance of mitochondrial dysfunctionality has not been studied in ductal carcinoma to the best of our knowledge. We used Raman spectroscopy and imaging to monitor changes in the redox state of the mitochondrial cytochromes in ex vivo surgically resected specimens of human breast tissues, and in vitro human breast cells of normal cells (MCF 10A), slightly malignant cells (MCF7) and highly aggressive cells (MDA-MB-231). We showed that Raman imaging provides insight into the biology of human breast ductal cancer. Here we show that proper concentration of monounsaturated fatty acids, saturated fatty acids, cardiolipin and Cyt c is critical in the correct breast ductal functioning and constitutes an important parameter to assess breast epithelial cells integrity and homeostasis. We look inside human breast ducts by Raman imaging answering fundamental questions about location and distribution of various biochemical components inside the lumen, epithelial cells of the duct and the extracellular matrix around the cancer duct during cancer development in situ. Our results show that human breast cancers demonstrate a redox imbalance compared to normal tissue. The reduced cytochrome c is upregulated in all stages of cancers development. The results of the paper shed light on a largely non-investigated issues regarding cytochromes and mitochondrial function in electron transfer chain. We found in histopathologically controlled breast cancer duct that Cyt c, cardiolipin, and palmitic acid are the main components inside the lumen of cancerous duct in situ. The presented results show direct evidence that Cyt c is released to the lumen from the epithelial cells in cancerous duct. In contrast the lumen in normal duct is empty and free of Cyt c. Our results demonstrate how Cyt c is likely to function in cancer development. We anticipate our results to be a starting point for more sophisticated in vitro and in vivo animal models. For example, the correlation between concentration of Cyt c and cancer grade could be tested in various types of cancer. Furthermore, Cyt c is a target of anti-cancer drug development and a well-defined and quantitative Raman based assay for oxidative phosphorylation and apoptosis will be relevant for such developments.

A Perspective on Medicinal Chemistry Approaches for Targeting Pyruvate Kinase M2

The allosteric regulation of pyruvate kinase M2 (PKM2) affects the switching of the PKM2 protein between the high-activity and low-activity states that allow ATP and lactate production, respectively. PKM2, in its low catalytic state (dimeric form), is chiefly active in metabolically energetic cells, including cancer cells. More recently, PKM2 has emerged as an attractive target due to its role in metabolic dysfunction and other interrelated conditions. PKM2 (dimer) activity can be inhibited by modulating PKM2 dimer-tetramer dynamics using either PKM2 inhibitors that bind at the ATP binding active site of PKM2 (dimer) or PKM2 activators that bind at the allosteric site of PKM2, thus activating PKM2 from the dimer formation to the tetrameric formation. The present perspective focuses on medicinal chemistry approaches to design and discover PKM2 inhibitors and activators and further provides a scope for the future design of compounds targeting PKM2 with better efficacy and selectivity.

Clinical Significance of the Duality of Wnt/β-Catenin Signaling in Human Hepatocellular Carcinoma

Combination therapy with immune checkpoint inhibitors (ICIs) and vascular endothelial growth factor inhibitors has been approved as a first-line treatment for unresectable hepatocellular carcinoma (HCC), indicating a critical role of ICIs in the treatment of HCC. However, 20% of patients do not respond effectively to ICIs; mutations in the activation of the Wnt/β-catenin pathway are known to contribute to primary resistance to ICIs. From this point of view, non-invasive detection of Wnt/β-catenin activation should be informative for the management of advanced HCC. Wnt/β-catenin mutations in HCC have a dual aspect, which results in two distinct tumor phenotypes. HCC with minimal vascular invasion, metastasis, and good prognosis is named the “Jekyll phenotype”, while the poorly differentiated HCC subset with frequent vascular invasion and metastasis, cancer stem cell features, and high serum Alpha fetoprotein levels, is named the “Hyde phenotype”. To differentiate these two HCC phenotypes, a combination of the hepatobiliary phase of gadolinium-ethoxybenzyl-diethylenetriamine (Gd-EOB-DTPA)-enhanced magnetic resonance imaging and fluoro-2-deoxy-D-glucose-PET/CT may be useful. The former is applicable for the detection of the Jekyll phenotype, as nodules present higher enhancement on the hepatobiliary phase, while the latter is likely to be informative for the detection of the Hyde phenotype by showing an increased glucose uptake.

PI3K Pathway Inhibition with NVP-BEZ235 Hinders Glycolytic Metabolism in Glioblastoma Multiforme Cells

Glioblastoma (GBM) is the most lethal primary brain cancer that lacks effective molecular targeted therapies. The PI3K/AKT/mTOR pathway is activated in 90% of all Glioblastoma multiforme (GBM) tumors. To gain insight into the impact of the PI3K pathway on GBM metabolism, we treated U87MG GBM cells with NVP-BEZ235 (PI3K and mTOR a dual inhibitor) and identified differentially expressed genes with RNA-seq analysis. RNA-seq identified 7803 differentially regulated genes in response to NVP-BEZ235. Gene Set Enrichment Analysis (GSEA) identified two glycolysis-related gene sets that were significantly enriched (p < 0.05) in control samples compared to NVP-BEZ235-treated samples. We validated the inhibition of glycolytic genes by NVP-BEZ235 and examined the impact of the FOXO1 inhibitor (AS1842856) on these genes in a set of GBM cell lines. FOXO1 inhibition alone was associated with reduced LDHA expression, but not ENO1 or PKM2. Bioinformatics analyses revealed that PI3K-impacted glycolytic genes were over-expressed and co-expressed in GBM clinical samples. The elevated expression of PI3K-impacted glycolytic genes was associated with poor prognosis in GBM based on Kaplan-Meier survival analyses. Our results suggest novel insights into hallmark metabolic reprogramming associated with the PI3K-mTOR dual inhibition.

Prognostic and predictive role of a metabolic rate-limiting enzyme signature in hepatocellular carcinoma

OBJECTIVES

Abnormal expression of metabolic rate-limiting enzymes drives the occurrence and progression of hepatocellular carcinoma (HCC). This study aimed to elucidate the comprehensive model of metabolic rate-limiting enzymes associated with the prognosis of HCC.

MATERIALS AND METHODS

HCC animal model and TCGA project were used to screen out differentially expressed metabolic rate-limiting enzyme. Cox regression, least absolute shrinkage and selection operation (LASSO) and experimentally verification were performed to identify metabolic rate-limiting enzyme signature. The area under the receiver operating characteristic curve (AUC) and prognostic nomogram were used to assess the efficacy of the signature in the three HCC cohorts (TCGA training cohort, internal cohort and an independent validation cohort).

RESULTS

A classifier based on three rate-limiting enzymes (RRM1, UCK2 and G6PD) was conducted and serves as independent prognostic factor. This effect was further confirmed in an independent cohort, which indicated that the AUC at year 5 was 0.715 (95% CI: 0.653-0.777) for clinical risk score, whereas it was significantly increased to 0.852 (95% CI: 0.798-0.906) when combination of the clinical with signature risk score. Moreover, a comprehensive nomogram including the signature and clinicopathological aspects resulted in significantly predict the individual outcomes.

CONCLUSIONS

Our results highlighted the prognostic value of rate-limiting enzymes in HCC, which may be useful for accurate risk assessment in guiding clinical management and treatment decisions.

Antitumor Mechanism of Hydroxycamptothecin via the Metabolic Perturbation of Ribonucleotide and Deoxyribonucleotide in Human Colorectal Carcinoma Cells

Hydroxycamptothecin (SN38) is a natural plant extract isolated from Camptotheca acuminate. It has a broad spectrum of anticancer activity through inhibition of DNA topoisomerase I, which could affect DNA synthesis and lead to DNA damage. Thus, the action of SN38 against cancers could inevitably affect endogenous levels of ribonucleotide (RNs) and deoxyribonucleotide (dRNs) that play critical roles in many biological processes, especially in DNA synthesis and repair. However, the exact impact of SN38 on RNs and dRNs is yet to be fully elucidated. In this study, we evaluated the anticancer effect and associated mechanism of SN38 in human colorectal carcinoma HCT 116 cells. As a result, SN38 could decrease the cell viability and induce DNA damage in a concentration-dependent manner. Furthermore, cell cycle arrest and intracellular nucleotide metabolism were perturbed due to DNA damage response, of which ATP, UTP, dATP, and TTP may be the critical metabolites during the whole process. Combined with the expression of deoxyribonucleoside triphosphates synthesis enzymes, our results demonstrated that the alteration and imbalance of deoxyribonucleoside triphosphates caused by SN38 was mainly due to the de novo nucleotide synthesis at 24 h, and subsequently the salvage pathways at 48 h. The unique features of SN38 suggested that it might be recommended as an effective supplementary drug with an anticancer effect.

Glutamate-Oxaloacetate Transaminase 1 Impairs Glycolysis by Interacting with Pyruvate Carboxylase and Further Inhibits the Malignant Phenotypes of Glioblastoma Cells

BACKGROUND

Glycolysis is an important metabolic manner in glioblastoma multiforme (GBM)'s rapid growth. It has been reported that glutamate-oxaloacetate transaminase 1 (GOT1) is low-expressed in GBM and patients with high-expressed GOT1 have better prognosis. However, the effect and mechanism of GOT1 on glycolysis and malignant phenotypes of GBM cells are still unclear.

METHODS

The expression differences of GOT1 between GBM parenchyma and adjacent tissues were detected. The prognosis and clinical data with different levels of GOT1 were also analyzed. The glucose consumption, production of lactate and pyruvate were measured after GOT1 was knocked down or overexpressed. The effects of GOT1 on GBM cell's malignant phenotypes were analyzed by Western blot, CCK-8 assay, and flow cytometry. The relationship between GOT1 and pyruvate carboxylase (PC) was examined by immunoprecipitation and immunofluorescence.

RESULTS

GOT1 was expressed little in GBM, and patients with highly expressed GOT1 had longer survival periods. Overexpressed GOT1 inhibited the glycolysis and malignant phenotypes of GBM cells. 2-DG treatment could partially reverse the enhancement of malignant phenotypes caused by knockdown of GOT1. The expression of GOT1 was positively correlated with PC. The inhibitory effect of GOT1 on glycolysis could be partially reversed by PC's knockdown.

CONCLUSIONS

GOT1 could impair glycolysis by interacting with PC and further inhibit the malignant phenotypes of GBM cells.

Benzo[f]indole-4,9-dione Derivatives Effectively Inhibit the Growth of Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is a subtype of breast cancer with poor clinical outcome, and currently no effective targeted therapies are available. Indole compounds have been shown to have potential antitumor activity against various cancer cells. In the present study, we found that new four benzo[f]indole-4,9-dione derivatives reduce TNBC cell viability by reactive oxygen species (ROS) accumulation stress in vitro. Further analyses showed that LACBio1, LACBio2, LACBio3 and LACBio4 exert cytotoxic effects on MDA-MB 231 cancer cell line by inducing the intrinsic apoptosis pathway, activating caspase 9 and Bax/Bcl-2 pathway in vitro. These results provide evidence that these new four benzo[f]indole-4,9-dione derivatives could be potential therapeutic agents against TNBC by promoting ROS stress-mediated apoptosis through intrinsic-pathway caspase activation.

Metabolic control of cancer progression as novel targets for therapy

Metabolism is an important part of tumorigenesis as well as progression. The various cancer metabolism pathways, such as glucose metabolism and glutamine metabolism, directly regulate the development and progression of cancer. The pathways by which the cancer cells rewire their metabolism according to their needs, surrounding environment and host tissue conditions are an important area of study. The regulation of these metabolic pathways is determined by various oncogenes, tumor suppressor genes, as well as various constituent cells of the tumor microenvironment. Expanded studies on metabolism will help identify efficient biomarkers for diagnosis and strategies for therapeutic interventions and countering ways by which cancers may acquire resistance to therapy.

Ketogenic Diet in Cancer Prevention and Therapy: Molecular Targets and Therapeutic Opportunities

Although cancer is still one of the most significant global challenges facing public health, the world still lacks complementary approaches that would significantly enhance the efficacy of standard anticancer therapies. One of the essential strategies during cancer treatment is following a healthy diet program. The ketogenic diet (KD) has recently emerged as a metabolic therapy in cancer treatment, targeting cancer cell metabolism rather than a conventional dietary approach. The ketogenic diet (KD), a high-fat and very-low-carbohydrate with adequate amounts of protein, has shown antitumor effects by reducing energy supplies to cells. This low energy supply inhibits tumor growth, explaining the ketogenic diet's therapeutic mechanisms in cancer treatment. This review highlights the crucial mechanisms that explain the ketogenic diet's potential antitumor effects, which probably produces an unfavorable metabolic environment for cancer cells and can be used as a promising adjuvant in cancer therapy. Studies discussed in this review provide a solid background for researchers and physicians to design new combination therapies based on KD and conventional therapies.

Unraveling the origin of glucose mediated disparate proliferation dynamics of cancer stem cells

Cancer stem cells (CSCs) often switch on their self-renewal programming aggressively to cause a relapse of cancer. Intriguingly, glucose triggers the proliferation propensities in CSCs by controlling the expression of the key transcription factor-like Nanog. However, the factors that critically govern this glucose-stimulated proliferation dynamics of CSCs remain elusive. Herein, by proposing a mathematical model of glucose-mediated Nanog regulation, we showed that the differential proliferation behavior of CSCs and cell-type similar to CSCs can be explained by considering the experimentally observed varied expression levels of key positive (STAT3) and negative (p53) regulators of Nanog. Our model reconciles various experimental observations and predicts ways to fine-tune the proliferation dynamics of these cell types in a context-dependent manner. In future, these modeling insights will be useful in developing improved therapeutic strategies to get rid of harmful CSCs.

Targeting pyruvate dehydrogenase kinase signaling in the development of effective cancer therapy

Pyruvate is irreversibly decarboxylated to acetyl coenzyme A by mitochondrial pyruvate dehydrogenase complex (PDC). Decarboxylation of pyruvate is considered a crucial step in cell metabolism and energetics. The cancer cells prefer aerobic glycolysis rather than mitochondrial oxidation of pyruvate. This attribute of cancer cells allows them to sustain under indefinite proliferation and growth. Pyruvate dehydrogenase kinases (PDKs) play critical roles in many diseases because they regulate PDC activity. Recent findings suggest an altered metabolism of cancer cells is associated with impaired mitochondrial function due to PDC inhibition. PDKs inhibit the PDC activity via phosphorylation of the E1a subunit and subsequently cause a glycolytic shift. Thus, inhibition of PDK is an attractive strategy in anticancer therapy. This review highlights that PDC/PDK axis could be implicated in cancer's therapeutic management by developing potential small-molecule PDK inhibitors. In recent years, a dramatic increase in the targeting of the PDC/PDK axis for cancer treatment gained an attention from the scientific community. We further discuss breakthrough findings in the PDC-PDK axis. In addition, structural features, functional significance, mechanism of activation, involvement in various human pathologies, and expression of different forms of PDKs (PDK1-4) in different types of cancers are discussed in detail. We further emphasized the gene expression profiling of PDKs in cancer patients to prognosis and therapeutic manifestations. Additionally, inhibition of the PDK/PDC axis by small molecule inhibitors and natural compounds at different clinical evaluation stages has also been discussed comprehensively.

Metabolomics of Gastric Cancer

Gastric cancer is the fourth most common malignancy worldwide and the third leading cause of cancer deaths. Recent metabolomics research has advanced our understanding of the relationship between metabolic reprogramming and gastric cancer progression and led to the discovery of metabolic targets for potential clinical applications and therapeutic interventions. As a powerful tool for metabolite and flux measurement, metabolomics not only allows a comprehensive analysis of metabolites and related metabolic pathways but also can investigate the interactions between gastric cancer cells and tumour microenvironment as well as between the cancer cells and gastric microbiome. In this chapter, we aim to summarize the recent advances in gastric cancer metabolism and discuss the applications of metabolomics for target discovery in gastric cancer.

Mechanisms of temozolomide resistance in glioblastoma - a comprehensive review

Glioblastoma (GBM) is the most common primary malignant brain tumor in adults and has an exceedingly low median overall survival of only 15 months. Current standard-of-care for GBM consists of gross total surgical resection followed by radiation with concurrent and adjuvant chemotherapy. Temozolomide (TMZ) is the first-choice chemotherapeutic agent in GBM; however, the development of resistance to TMZ often becomes the limiting factor in effective treatment. While O6-methylguanine-DNA methyltransferase repair activity and uniquely resistant populations of glioma stem cells are the most well-known contributors to TMZ resistance, many other molecular mechanisms have come to light in recent years. Key emerging mechanisms include the involvement of other DNA repair systems, aberrant signaling pathways, autophagy, epigenetic modifications, microRNAs, and extracellular vesicle production. This review aims to provide a comprehensive overview of the clinically relevant molecular mechanisms and their extensive interconnections to better inform efforts to combat TMZ resistance.

Signaling pathways in intestinal homeostasis and colorectal cancer: KRAS at centre stage

The intestinal epithelium acts as a physical barrier that separates the intestinal microbiota from the host and is critical for preserving intestinal homeostasis. The barrier is formed by tightly linked intestinal epithelial cells (IECs) (i.e. enterocytes, goblet cells, neuroendocrine cells, tuft cells, Paneth cells, and M cells), which constantly self-renew and shed. IECs also communicate with microbiota, coordinate innate and adaptive effector cell functions. In this review, we summarize the signaling pathways contributing to intestinal cell fates and homeostasis functions. We focus especially on intestinal stem cell proliferation, cell junction formation, remodelling, hypoxia, the impact of intestinal microbiota, the immune system, inflammation, and metabolism. Recognizing the critical role of KRAS mutants in colorectal cancer, we highlight the connections of KRAS signaling pathways in coordinating these functions. Furthermore, we review the impact of KRAS colorectal cancer mutants on pathway rewiring associated with disruption and dysfunction of the normal intestinal homeostasis. Given that KRAS is still considered undruggable and the development of treatments that directly target KRAS are unlikely, we discuss the suitability of targeting pathways downstream of KRAS as well as alterations of cell extrinsic/microenvironmental factors as possible targets for modulating signaling pathways in colorectal cancer.

MicroRNA-202 suppresses glycolysis of pancreatic cancer by targeting hexokinase 2

Purpose: Various studies have identified miR-202 critically participated in the development of different cancers. However, the potential mechanisms underlying the carcinogenesis of pancreatic cancer (PC) still remains elusive. Methods: In the study, cell proliferation assay, colony formation assay, EdU incorporation assay, Luciferase reporter assay, lactate production, glucose consumption assay, real-time PCR and western blot were used to investigate the mechanism of hexokinase 2 (HK2) regulated by miR-202 in pancreatic cancer in vitro and in vivo. Results: Here we found that miR-202 was decreased in the PC tissues, and its low expression was correlated with a poor prognosis of PC patients. Overexpression of miR-202 in PC cells reduced cell proliferation and tumorigenesis by impairing glycolysis, while downregulation of miR-202 promoted the cells proliferative capacity. Mechanically, we demonstrated that HK2, an enzyme that catalyzes the irreversible rate-limiting step of glycolysis, as the direct target of miR-202. Overexpression of miR-202 suppressed both the mRNA and protein levels of HK2, whereas re-introduction of HK2 abrogated miR-202-mediated glycolytic inhibition. In addition, the expression of miR-202 was negatively associated with HK2 level in a cohort of PC tissues. Conclusion: Our findings validate the mechanism that miR-202 reprograms the metabolic process to promote PC progression, thus providing potential prognostic predictors for PC patients.

Metabolic crosstalk in the tumor microenvironment regulates antitumor immunosuppression and immunotherapy resisitance

The successful treatment of human cancers by immunotherapy has been made possible by breakthroughs in the discovery of immune checkpoint regulators, including CTLA-4 and PD-1/PD-L1. However, the immunosuppressive effect of the tumor microenvironment still represents an important bottleneck that limits the success of immunotherapeutic approaches. The tumor microenvironment influences the metabolic crosstalk between tumor cells and tumor-infiltrating immune cells, creating competition for the utilization of nutrients and promoting immunosuppression. In addition, tumor-derived metabolites regulate the activation and effector function of immune cells through a variety of mechanisms; in turn, the metabolites and other factors secreted by immune cells can also become accomplices to cancer development. Immune-metabolic checkpoint regulation is an emerging concept that is being studied with the aim of restoring the immune response in the tumor microenvironment. In this review, we summarize the metabolic reprogramming of various cell types present in the tumor microenvironment, with a focus on the interaction between the metabolic pathways of these cells and antitumor immunosuppression. We also discuss the main metabolic checkpoints that could provide new means of enhancing antitumor immunotherapy.

Leucine and branched-chain amino acid metabolism contribute to the growth of bone sarcomas by regulating AMPK and mTORC1 signaling

Osteosarcoma and chondrosarcoma are sarcomas of the bone and the cartilage that are primarily treated by surgical intervention combined with high toxicity chemotherapy. In search of alternative metabolic approaches to address the challenges in treating bone sarcomas, we assessed the growth dependence of these cancers on leucine, one of the branched-chain amino acids (BCAAs), and BCAA metabolism. Tumor biopsies from bone sarcoma patients revealed differential expression of BCAA metabolic enzymes. The cytosolic branched-chain aminotransferase (BCATc) that is commonly overexpressed in cancer cells, was down-regulated in chondrosarcoma (SW1353) in contrast with osteosarcoma (143B) cells that expressed both BCATc and its mitochondrial isoform BCATm. Treating SW1353 cells with gabapentin, a selective inhibitor of BCATc, further revealed that these cells failed to respond to gabapentin. Application of the structural analog of leucine, N-acetyl-leucine amide (NALA) to disrupt leucine uptake, indicated that all bone sarcoma cells used leucine to support their energy metabolism and biosynthetic demands. This was evident from the increased activity of the energy sensor AMP-activated protein kinase (AMPK), down-regulation of complex 1 of the mammalian target of rapamycin (mTORC1), and reduced cell viability in response to NALA. The observed changes were most profound in the 143B cells, which appeared highly dependent on cytosolic and mitochondrial BCAA metabolism. This study thus demonstrates that bone sarcomas rely on leucine and BCAA metabolism for energy and growth; however, the differential expression of BCAA enzymes and the presence of other carbon sources may dictate how efficiently these cancer cells take advantage of BCAA metabolism.

Clinical proteomics for prostate cancer: understanding prostate cancer pathology and protein biomarkers for improved disease management

Following the introduction of routine Prostate Specific Antigen (PSA) screening in the early 1990′s, Prostate Cancer (PCa) is often detected at an early stage. There are also a growing number of treatment options available and so the associated mortality rate is generally low. However, PCa is an extremely complex and heterogenous disease and many patients suffer disease recurrence following initial therapy. Disease recurrence commonly results in metastasis and metastatic PCa has an average survival rate of just 3–5 years. A significant problem in the clinical management of PCa is being able to differentiate between patients who will respond to standard therapies and those who may benefit from more aggressive intervention at an earlier stage. It is also acknowledged that for many men the disease is not life threatenting. Hence, there is a growing desire to identify patients who can be spared the significant side effects associated with PCa treatment until such time (if ever) their disease progresses to the point where treatment is required. To these important clinical needs, current biomarkers and clinical methods for patient stratification and personlised treatment are insufficient. This review provides a comprehensive overview of the complexities of PCa pathology and disease management. In this context it is possible to review current biomarkers and proteomic technologies that will support development of biomarker-driven decision tools to meet current important clinical needs. With such an in-depth understanding of disease pathology, the development of novel clinical biomarkers can proceed in an efficient and effective manner, such that they have a better chance of improving patient outcomes.

A tumour suppressive relationship between mineralocorticoid and retinoic acid receptors activates a transcriptional program consistent with a reverse Warburg effect in breast cancer

Background

The role of nuclear receptors in both the aetiology and treatment of breast cancer is exemplified by the use of the oestrogen receptor (ER) as a prognostic marker and treatment target. Treatments targeting the oestrogen signalling pathway are initially highly effective for most patients. However, for the breast cancers that fail to respond, or become resistant, to current endocrine treatments, the long-term outlook is poor. ER is a member of the nuclear receptor superfamily, comprising 48 members in the human, many of which are expressed in the breast and could be used as alternative targets in cases where current treatments are ineffective.

Methods

We used sparse canonical correlation analysis to interrogate potential novel nuclear receptor expression relationships in normal breast and breast cancer. These were further explored using whole transcriptome profiling in breast cancer cells after combinations of ligand treatments.

Results

Using this approach, we discovered a tumour suppressive relationship between the mineralocorticoid receptor (MR) and retinoic acid receptors (RAR), in particular RARβ. Expression profiling of MR expressing breast cancer cells revealed that mineralocorticoid and retinoid co-treatment activated an expression program consistent with a reverse Warburg effect and growth inhibition, which was not observed with either ligand alone. Moreover, high expression of both MR and RARB was associated with improved breast cancer-specific survival.

Conclusion

Our study reveals a previously unknown relationship between MR and RAR in the breast, which is dependent on menopausal state and altered in malignancy. This finding identifies potential new targets for the treatment of breast cancers that are refractory to existing therapeutic options.

Supplementary information

Supplementary information accompanies this paper at 10.1186/s13058-020-01355-x.

Metabolic Roles of Androgen Receptor and Tip60 in Androgen-Dependent Prostate Cancer

Androgen receptor (AR)-mediated signaling is essential for the growth and differentiation of the normal prostate and is the primary target for androgen deprivation therapy in prostate cancer. Tat interactive protein 60 kDa (Tip60) is a histone acetyltransferase that is critical for AR activation. It is well known that cancer cells rewire their metabolic pathways in order to sustain aberrant proliferation. Growing evidence demonstrates that the AR and Tip60 modulate key metabolic processes to promote the survival of prostate cancer cells, in addition to their classical roles. AR activation enhances glucose metabolism, including glycolysis, tricarboxylic acid cycle and oxidative phosphorylation, as well as lipid metabolism in prostate cancer. The AR also interacts with other metabolic regulators, including calcium/calmodulin-dependent kinase kinase 2 and mammalian target of rapamycin. Several studies have revealed the roles of Tip60 in determining cell fate indirectly by modulating metabolic regulators, such as c-Myc, hypoxia inducible factor 1α (HIF-1α) and p53 in various cancer types. Furthermore, Tip60 has been shown to regulate the activity of key enzymes in gluconeogenesis and glycolysis directly through acetylation. Overall, both the AR and Tip60 are master metabolic regulators that mediate cellular energy metabolism in prostate cancer, providing a framework for the development of novel therapeutic targets in androgen-dependent prostate cancer.

Association between Metabolites and the Risk of Lung Cancer: A Systematic Literature Review and Meta-Analysis of Observational Studies

Globally, lung cancer is the most prevalent cancer type. However, screening and early detection is challenging. Previous studies have identified metabolites as promising lung cancer biomarkers. This systematic literature review and meta-analysis aimed to identify metabolites associated with lung cancer risk in observational studies. The literature search was performed in PubMed and EMBASE databases, up to 31 December 2019, for observational studies on the association between metabolites and lung cancer risk. Heterogeneity was assessed using the I² statistic and Cochran’s Q test. Meta-analyses were performed using either a fixed-effects or random-effects model, depending on study heterogeneity. Fifty-three studies with 297 metabolites were included. Most identified metabolites (252 metabolites) were reported in individual studies. Meta-analyses were conducted on 45 metabolites. Five metabolites (cotinine, creatinine riboside, N-acetylneuraminic acid, proline and r-1,t-2,3,c-4-tetrahydroxy-1,2,3,4-tetrahydrophenanthrene) and five metabolite groups (total 3-hydroxycotinine, total cotinine, total nicotine, total 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (sum of concentrations of the metabolite and its glucuronides), and total nicotine equivalent (sum of total 3-hydroxycotinine, total cotinine and total nicotine)) were associated with higher lung cancer risk, while three others (folate, methionine and tryptophan) were associated with lower lung cancer risk. Significant heterogeneity was detected across most studies. These significant metabolites should be further evaluated as potential biomarkers for lung cancer.

Probing metabolic alterations in breast cancer in response to molecular inhibitors with Raman spectroscopy and validated with mass spectrometry

Rapid and accurate response to targeted therapies is critical to differentiate tumors that are resistant to treatment early in the regimen. In this work, we demonstrate a rapid, noninvasive, and label-free approach to evaluate treatment response to molecular inhibitors in breast cancer (BC) cells with Raman spectroscopy (RS). Metabolic reprogramming in BC was probed with RS and multivariate analysis was applied to classify the cells into responsive or nonresponsive groups as a function of drug dosage, drug type, and cell type. Metabolites identified with RS were then validated with mass spectrometry (MS). We treated triple-negative BC cells with Trametinib, an inhibitor of the extracellular-signal-regulated kinase (ERK) pathway. Changes measured with both RS and MS corresponding to membrane phospholipids, amino acids, lipids and fatty acids indicated that these BC cells were responsive to treatment. Comparatively, minimal metabolic changes were observed post-treatment with Alpelisib, an inhibitor of the mammalian target of rapamycin (mTOR) pathway, indicating treatment resistance. These findings were corroborated with cell viability assay and immunoblotting. We also showed estrogen receptor-positive MCF-7 cells were nonresponsive to Trametinib with minimal metabolic and viability changes. Our findings support that oncometabolites identified with RS will ultimately enable rapid drug screening in patients ensuring patients receive the most effective treatment at the earliest time point.

Identification of CPT1A as a Prognostic Biomarker and Potential Therapeutic Target for Kidney Renal Clear Cell Carcinoma and Establishment of a Risk Signature of CPT1A-Related Genes

This study is aimed at investigating the expression, clinical significance, and biological role of CPT1A in kidney renal clear cell carcinoma (KIRC). We used the TCGA database and clinical pathology of tissue specimens to study the expression of CPT1A in KIRC. The expression of CPT1A in the kidney cancer tissue was significantly lower than that in the normal tissue. Survival curves demonstrated that the expression was correlated with prognosis in patients. We used the plasmid transfection method to explore the biological role of CPT1A in renal cancer cells and performed CCK-8, wound healing, and Transwell invasion experiments. The results demonstrated that CPT1A can inhibit the proliferation, migration, and invasion of renal cancer cells. Subsequently, we employed a bioinformatics analysis to further elucidate the role of CPT1A. The PPI network diagram was plotted, along with the coexpression diagram, between CPT1A and ten associated genes. The heat map was plotted, and the hazard ratio analysis of these eleven genes in KIRC was performed. Furthermore, the CPT1A, LPL, CPT2, and EHHADH genes were used to establish a reliable prognostic risk signature in KIRC. GSEA analysis demonstrated that CPT1A modulates tumor development via a variety of biological pathways in KIRC. We believe that CPT1A most likely suppresses tumor progression by employing tumor "slimming" in KIRC. Collectively, the results indicate the potential of CPT1A as a novel prognostic indicator and potential therapeutic target in KIRC.

Gut Microbiota during Dietary Restrictions: New Insights in Non-Communicable Diseases

In recent decades, there has been a growing interest in dietary restrictions for their promising effects on longevity and health span. Indeed, these strategies are supposed to delay the onset and burden of non-communicable diseases (NCDs) such as obesity, diabetes, cancer and neurological and gastrointestinal inflammatory diseases. At the same time, the gut microbiota has been shown to play a crucial role in NCDs since it is actively involved in maintaining gut homeostasis through its impact on nutrients metabolism, gut barrier, and immune system. There is evidence that dietary restrictions could slow down age-related changes in the types and numbers of gut bacteria, which may counteract gut dysbiosis. The beneficial effects on gut microbiota may positively influence host metabolism, gut barrier permeability, and brain functions, and subsequently, postpone the onset of NCDs prolonging the health span. These new insights could lead to the development of novel strategies for modulating gut microbiota with the end goal of treating/preventing NCDs. This review provides an overview of animal and human studies focusing on gut microbiota variations during different types of dietary restriction, in order to highlight the close relationship between gut microbiota balance and the host's health benefits induced by these nutritional regimens.

Lysine oxidase exposes a dependency on the thioredoxin antioxidant pathway in triple-negative breast cancer cells

PURPOSE

Transformed cells are vulnerable to depletion of certain amino acids. Lysine oxidase (LO) catalyzes the oxidative deamination of lysine, resulting in lysine depletion and hydrogen peroxide production. Although LO has broad antitumor activity in preclinical models, the cytotoxic mechanisms of LO are poorly understood.

METHODS

Triple (ER/PR/HER2)-negative breast cancer (TNBC) cells were treated with control media, lysine-free media or control media supplemented with LO and examined for cell viability, caspase activation, induction of reactive oxygen species (ROS) and antioxidant signaling. To determine the role of nuclear factor erythroid 2-related factor 2 (NRF2) and thioredoxin reductase-1 (TXNRD1) in LO-induced cell death, NRF2 and TXNRD1 were individually silenced by RNAi. Additionally, the pan-TXNRD inhibitor auranofin was used in combination with LO.

RESULTS

LO activates caspase-independent cell death that is suppressed by necroptosis and ferroptosis inhibitors, which are inactive against lysine depletion, pointing to fundamental differences between LO and lysine depletion. LO rapidly induces ROS with a return to baseline levels within 24 h that coincides temporally with induction of TXNRD activity, the rate-limiting enzyme in the thioredoxin antioxidant pathway. ROS induction is required for LO-mediated cell death and NRF2-dependent induction of TXNRD1. Silencing NRF2 or TXNRD1 enhances the cytotoxicity of LO. The pan-TXNRD inhibitor auranofin is synergistic with LO against transformed breast epithelial cells, but not untransformed cells, underscoring the tumor-selectivity of this strategy.

CONCLUSIONS

LO exposes a redox vulnerability of TNBC cells to TXNRD inhibition by rendering tumor cells dependent on the thioredoxin antioxidant pathway for survival.

The mevalonate precursor enzyme HMGCS1 is a novel marker and key mediator of cancer stem cell enrichment in luminal and basal models of breast cancer

The definitive characterization of common cancer stem cell (CSCs) subpopulations in breast cancer subtypes with distinct genotypic and phenotypic features remains an ongoing challenge. In this study, we have used a non-biased genome wide screening approach to identify transcriptional networks that may be specific to the CSC subpopulations in both luminal and basal breast cancer subtypes. In depth studies of three CSC-enriched breast cancer cell lines representing various subtypes of breast cancer revealed a striking hyperactivation of the mevalonate metabolic pathway in comparison to control cells. The upregulation of metabolic networks is a key feature of tumour cells securing growth and proliferative capabilities and dysregulated mevalonate metabolism has been associated with tumour malignancy and cellular transformation in breast cancer. Furthermore, accumulating evidence suggests that Simvastatin therapy, a mevalonate pathway inhibitor, could affect breast cancer progression and reduce breast cancer recurrence. When detailing the mevalonate pathway in breast cancer using a single-cell qPCR, we identified the mevalonate precursor enzyme, HMGCS1, as a specific marker of CSC-enriched subpopulations within both luminal and basal tumour subtypes. Down-regulation of HMGCS1 also decreased the CSC fraction and function in various model systems, suggesting that HMGCS1 is essential for CSC-activities in breast cancer in general. These data was supported by strong associations between HMGCS1 expression and aggressive features, such as high tumour grade, p53 mutations as well as ER-negativity in lymph node positive breast cancer. Importantly, loss of HMGCS1 also had a much more pronounced effect on CSC-activities compared to treatment with standard doses of Simvastatin. Taken together, this study highlights HMGCS1 as a potential gatekeeper for dysregulated mevalonate metabolism important for CSC-features in both luminal and basal breast cancer subtypes. Pharmacological inhibition of HMGCS1 could therefore be a superior novel treatment approach for breast cancer patients via additional CSC blocking functions.

Amino acid-modified PAMAM dendritic nanocarriers as effective chemotherapeutic drug vehicles in cancer treatment: a study using zebrafish as a cancer model

The use of nanomaterials for drug delivery offers many advantages including the targeted delivery of drugs and their controlled release. Nonetheless, entry into the target cells remains a challenge for many nanomaterials used for drug delivery. Moreover, cellular uptake limits the therapeutic efficiency of many anticancer drugs. An important goal is to increase the specific accumulation of these nanoparticles (NPs) at the desired cancerous tissues. Notably, cancer cells show a high demand for some amino acids and we have used this knowledge to develop novel carrier systems. In this study, drug carriers were produced by the conjugation of multiple amino acids such as l-histidine (H) and l-cysteine (C) or single amino acids such as only H with the G4.5 dendrimers (G) to produce GHC aggregates and GH NP carriers, respectively. Doxorubicin was loaded into the G4.5, GH, and GHC dendrimers (G/DOX, GH/DOX and GHC/DOX, respectively) and the release mechanism was demonstrated at pH 7.4 and pH 5.0. GH/DOX and GHC/DOX showed better stability under physiological conditions than the dendrimer alone (G/DOX). GH/DOX and GHC/DOX exhibited higher inhibition of HeLa cell proliferation in in vitro and in vivo studies in zebrafish, confirming the early release of DOX by disrupting the endosomal membrane and triggering the destabilization of carriers at a lower pH of 5.0.