Glucose deprivation contributes to the development of KRAS pathway mutations in tumor cells

Extracellular Vesicles Derived-LAT1 mRNA as a Powerful Inducer of Colorectal Cancer Aggressive Phenotype

Colorectal cancer (CRC) is the third most common cancer in the world and represents the third most deadly tumor worldwide. About 15–25% of patients present metastasis in the moment of diagnosis, the liver being the most common site of metastization. Therefore, the development of new therapeutic agents is needed, to improve the patients’ prognosis. Amino acids transporters, LAT1 and ASCT2, are described as upregulated in CRC, being associated with a poor prognosis. Extracellular vesicles have emerged as key players in cell-to-cell communication due to their ability to transfer biomolecules between cells, with a phenotypic impact on the recipient cells. Thus, this study analyzes the presence of LAT1 and ASCT2 mRNAs in CRC-EVs and evaluates their role in phenotype modulation in a panel of four recipient cell lines (HCA-7, HEPG-2, SK-HEP-1, HKC-8). We found that HCT 116-EVs carry LAT1, ASCT2 and other oncogenic mRNAs being taken up by recipient cells. Moreover, the HCT 116-EVs’ internalization was associated with the increase of LAT1 mRNA in SK-HEP-1 cells. We also observed that HCT 116-EVs induce a higher cell migration capacity and proliferation of SK-HEP-1 and HKC-8 cells. The present study supports the LAT1-EVs’ mRNA involvement in cell phenotype modulation, conferring advantages in cell migration and proliferation.

Metabolic drug survey highlights cancer cell dependencies and vulnerabilities

Interrogation of cellular metabolism with high-throughput screening approaches can unravel contextual biology and identify cancer-specific metabolic vulnerabilities. To systematically study the consequences of distinct metabolic perturbations, we assemble a comprehensive metabolic drug library (CeMM Library of Metabolic Drugs; CLIMET) covering 243 compounds. We, next, characterize it phenotypically in a diverse panel of myeloid leukemia cell lines and primary patient cells. Analysis of the drug response profiles reveals that 77 drugs affect cell viability, with the top effective compounds targeting nucleic acid synthesis, oxidative stress, and the PI3K/mTOR pathway. Clustering of individual drug response profiles stratifies the cell lines into five functional groups, which link to specific molecular and metabolic features. Mechanistic characterization of selective responses to the PI3K inhibitor pictilisib, the fatty acid synthase inhibitor GSK2194069, and the SLC16A1 inhibitor AZD3965, bring forth biomarkers of drug response. Phenotypic screening using CLIMET represents a valuable tool to probe cellular metabolism and identify metabolic dependencies at large.

Pathological Features and Prognostication in Colorectal Cancer

The prognostication of colorectal cancer (CRC) has traditionally relied on staging as defined by the Union for International Cancer Control (UICC) and American Joint Committee on Cancer (AJCC) TNM staging classifications. However, clinically, there appears to be differences in survival patterns independent of stage, suggesting a complex interaction of stage, pathological features, and biomarkers playing a role in guiding prognosis, risk stratification, and guiding neoadjuvant and adjuvant therapies. Histological features such as tumour budding, perineural invasion, apical lymph node involvement, lymph node yield, lymph node ratio, and molecular features such as MSI, KRAS, BRAF, and CDX2 may assist in prognostication and optimising adjuvant treatment. This study provides a comprehensive review of the pathological features and biomarkers that are important in the prognostication and treatment of CRC. We review the importance of pathological features and biomarkers that may be important in colorectal cancer based on the current evidence in the literature.

A Novel Microcrystalline BAY-876 Formulation Achieves Long-Acting Antitumor Activity Against Aerobic Glycolysis and Proliferation of Hepatocellular Carcinoma

BAY-876 is an effective antagonist of the Glucose transporter type 1 (GLUT1) receptor, a mediator of aerobic glycolysis, a biological process considered a hallmark of hepatocellular carcinoma (HCC) together with cell proliferation, drug-resistance, and metastasis. However, the clinical application of BAY-876 has faced many challenges. In the presence study, we describe the formulation of a novel microcrystalline BAY-876 formulation. A series of HCC tumor models were established to determine not only the sustained release of microcrystalline BAY-876, but also its long-acting antitumor activity. The clinical role of BAY-876 was confirmed by the increased expression of GLUT1, which was associated with the worse prognosis among advanced HCC patients. A single dose of injection of microcrystalline BAY-876 directly in the HCC tissue achieved sustained localized levels of Bay-876. Moreover, the single injection of microcrystalline BAY-876 in HCC tissues not only inhibited glucose uptake and prolonged proliferation of HCC cells, but also inhibited the expression of epithelial-mesenchymal transition (EMT)-related factors. Thus, the microcrystalline BAY-876 described in this study can directly achieve promising localized effects, given its limited diffusion to other tissues, thereby reducing the occurrence of potential side effects, and providing an additional option for advanced HCC treatment.

Elucidating tumor-stromal metabolic crosstalk in colorectal cancer through integration of constraint-based models and LC-MS metabolomics

Colorectal cancer (CRC) is a major cause of morbidity and mortality in the United States. Tumor-stromal metabolic crosstalk in the tumor microenvironment promotes CRC development and progression, but exactly how stromal cells, in particular cancer-associated fibroblasts (CAFs), affect the metabolism of tumor cells remains unknown. Here we take a data-driven approach to investigate the metabolic interactions between CRC cells and CAFs, integrating constraint-based modeling and metabolomic profiling. Using metabolomics data, we perform unsteady-state parsimonious flux balance analysis to infer flux distributions for central carbon metabolism in CRC cells treated with or without CAF-conditioned media. We find that CAFs reprogram CRC metabolism through stimulation of glycolysis, the oxidative arm of the pentose phosphate pathway (PPP), and glutaminolysis, as well as inhibition of the tricarboxylic acid cycle. To identify potential therapeutic targets, we simulate enzyme knockouts and find that CAF-treated CRC cells are especially sensitive to inhibitions of hexokinase and glucose-6-phosphate, the rate limiting steps of glycolysis and oxidative PPP. Our work gives mechanistic insights into the metabolic interactions between CRC cells and CAFs and provides a framework for testing hypotheses towards CRC-targeted therapies.

The Crosstalk Between Signaling Pathways and Cancer Metabolism in Colorectal Cancer

Colorectal cancer (CRC) is one of the most frequently diagnosed cancers worldwide. Metabolic reprogramming represents an important cancer hallmark in CRC. Reprogramming core metabolic pathways in cancer cells, such as glycolysis, glutaminolysis, oxidative phosphorylation, and lipid metabolism, is essential to increase energy production and biosynthesis of precursors required to support tumor initiation and progression. Accumulating evidence demonstrates that activation of oncogenes and loss of tumor suppressor genes regulate metabolic reprogramming through the downstream signaling pathways. Protein kinases, such as AKT and c-MYC, are the integral components that facilitate the crosstalk between signaling pathways and metabolic pathways in CRC. This review provides an insight into the crosstalk between signaling pathways and metabolic reprogramming in CRC. Targeting CRC metabolism could open a new avenue for developing CRC therapy by discovering metabolic inhibitors and repurposing protein kinase inhibitors/monoclonal antibodies.

KRAS mutation: from undruggable to druggable in cancer

Cancer is the leading cause of death worldwide, and its treatment and outcomes have been dramatically revolutionised by targeted therapies. As the most frequently mutated oncogene, Kirsten rat sarcoma viral oncogene homologue (KRAS) has attracted substantial attention. The understanding of KRAS is constantly being updated by numerous studies on KRAS in the initiation and progression of cancer diseases. However, KRAS has been deemed a challenging therapeutic target, even "undruggable", after drug-targeting efforts over the past four decades. Recently, there have been surprising advances in directly targeted drugs for KRAS, especially in KRAS (G12C) inhibitors, such as AMG510 (sotorasib) and MRTX849 (adagrasib), which have obtained encouraging results in clinical trials. Excitingly, AMG510 was the first drug-targeting KRAS (G12C) to be approved for clinical use this year. This review summarises the most recent understanding of fundamental aspects of KRAS, the relationship between the KRAS mutations and tumour immune evasion, and new progress in targeting KRAS, particularly KRAS (G12C). Moreover, the possible mechanisms of resistance to KRAS (G12C) inhibitors and possible combination therapies are summarised, with a view to providing the best regimen for individualised treatment with KRAS (G12C) inhibitors and achieving truly precise treatment.

Exploring Better Strategies for RAS Mutation-Associated EGFR-Targeted Resistance in Colorectal Cancer: From the Perspective of Cancer Community Ecology

RAS is the most common mutated gene in colorectal cancer (CRC), and its occurrence is associated with primary and acquired resistance to anti-epidermal growth factor receptor (EGFR) blockade. Cancer community ecology, such as the competitive exclusion principle, is a valuable focus and would contribute to the understanding of drug resistance. We have presented several articles on RAS mutant clonal evolution monitoring during anti-EGFR treatment in CRC. In these articles, the availability of serially collected samples provided a unique opportunity to model the tumor evolutionary process from the perspective of cancer community ecology in those patients upon treatment. In this perspective article, we presented a theoretical basis and evidence from several experimental or phase II clinical trials for the contemporary application of ecological mechanisms in CRC treatment. In general, a reduction in targetable RAS wild-type cells to a maximum tolerated extent, such as continuous treatment, might lead to the competitive release of inextirpable RAS mutant cells and cancer progression. A full understanding of subclonal competition might be beneficial in managing CRC. Several ecological strategies, including anti-EGFR treatment reintroduced at an appropriate point of time for RAS mutant patients, intermittent treatment instead of continuous treatment, the appropriate sequence of nonselective targeted therapy, and combination therapy, were proposed.

Cartilage Oligomeric Matrix Protein, COMP may be a Better Prognostic Marker Than CEACAM5 and Correlates With Colon Cancer Molecular Subtypes, Tumor Aggressiveness and Overall Survival

BACKGROUND

New tumor biomarkers are needed to improve the management of Colon cancer (CC), the second leading cause of cancer-related deaths in the United States. Carcinoembryonic Antigen (CEA), the translated protein of carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) gene, is used as a biomarker for CC. Cartilage Oligomeric Matrix Protein (COMP) is overexpressed in CC compared to normal colon tissues. This study aims to evaluate the expression of COMP by disease stage, consensus molecular subtype (CMS), its impact on disease outcomes, and comparison to CEACAM5.

MATERIALS AND METHODS

RNA-seq data from 456 CC The Cancer Genome Atlas samples and 41 matching control samples were analyzed for COMP expression and CEACAM5 expression. We stratified tumor samples by stage (I-IV), subtype (CMS1-CMS4), tumor location, and Kirsten RAt Sarcoma (KRAS) mutant status and three quartiles were established based on COMP expression. Kaplan Meier survival outcomes were evaluated.

RESULTS

COMP expression was significantly higher in tumor samples, with elevation of expression occurring in stage I and significantly increasing in stage IV. Increased COMP expression occurs in CMS4 with relatively low expression in CMS3. No significant expression difference was attributed to tumor location and KRAS mutant status. Compared to CEACAM5, COMP was a stronger molecular marker across stages and subtypes. CMS4 was associated with the high COMP expression, and higher levels of COMP were associated with poorer overall survival, disease-specific survival, and tumor progression-free intervals. CMS2 and 3 were associated with low expression and better survival.

CONCLUSION

COMP is a potential molecular biomarker for CC and may be superior to CEA as an indicator of CC.

Interplay between Epigenetics and Cellular Metabolism in Colorectal Cancer

Cellular metabolism alterations have been recognized as one of the most predominant hallmarks of colorectal cancers (CRCs). It is precisely regulated by many oncogenic signaling pathways in all kinds of regulatory levels, including transcriptional, post-transcriptional, translational and post-translational levels. Among these regulatory factors, epigenetics play an essential role in the modulation of cellular metabolism. On the one hand, epigenetics can regulate cellular metabolism via directly controlling the transcription of genes encoding metabolic enzymes of transporters. On the other hand, epigenetics can regulate major transcriptional factors and signaling pathways that control the transcription of genes encoding metabolic enzymes or transporters, or affecting the translation, activation, stabilization, or translocation of metabolic enzymes or transporters. Interestingly, epigenetics can also be controlled by cellular metabolism. Metabolites not only directly influence epigenetic processes, but also affect the activity of epigenetic enzymes. Actually, both cellular metabolism pathways and epigenetic processes are controlled by enzymes. They are highly intertwined and are essential for oncogenesis and tumor development of CRCs. Therefore, they are potential therapeutic targets for the treatment of CRCs. In recent years, both epigenetic and metabolism inhibitors are studied for clinical use to treat CRCs. In this review, we depict the interplay between epigenetics and cellular metabolism in CRCs and summarize the underlying molecular mechanisms and their potential applications for clinical therapy.

AMPKα loss promotes KRAS-mediated lung tumorigenesis

AMP-activated protein kinase (AMPK) is a critical sensor of energy status that coordinates cell growth with energy balance. In non-small cell lung cancer (NSCLC) the role of AMPKα is controversial and its contribution to lung carcinogenesis is not well-defined. Furthermore, it remains largely unknown whether long non-coding RNAs (lncRNAs) are involved in the regulation of AMPK-mediated pathways. Here, we found that loss of AMPKα in combination with activation of mutant KRAS^G12D increased lung tumour burden and reduced survival in Kras^LSLG12D/+/AMPKα^fl/fl mice. In agreement, functional in vitro studies revealed that AMPKα silencing increased growth and migration of NSCLC cells. In addition, we identified an AMPKα-modulated lncRNA, KIMAT1 (ENSG00000228709), which in turn regulates AMPKα activation by stabilizing the lactate dehydrogenase B (LDHB). Collectively, our study indicates that AMPKα loss promotes KRAS-mediated lung tumorigenesis and proposes a novel KRAS/KIMAT1/LDHB/AMPKα axis that could be exploited for therapeutic purposes.

Genetic Mutations and Non-Coding RNA-Based Epigenetic Alterations Mediating the Warburg Effect in Colorectal Carcinogenesis

Colorectal cancer (CRC) development is a gradual process defined by the accumulation of numerous genetic mutations and epigenetic alterations leading to the adenoma-carcinoma sequence. Despite significant advances in the diagnosis and treatment of CRC, it continues to be a leading cause of cancer-related deaths worldwide. Even in the presence of oxygen, CRC cells bypass oxidative phosphorylation to produce metabolites that enable them to proliferate and survive-a phenomenon known as the "Warburg effect". Understanding the complex glucose metabolism in CRC cells may support the development of new diagnostic and therapeutic approaches. Here we discuss the most recent findings on genetic mutations and epigenetic modulations that may positively or negatively regulate the Warburg effect in CRC cells. We focus on the non-coding RNA (ncRNA)-based epigenetics, and we present a perspective on the therapeutic relevance of critical molecules and ncRNAs mediating the Warburg effect in CRC cells. All the relevant studies were identified and assessed according to the genes and enzymes mediating the Warburg effect. The findings summarized in this review should provide a better understanding of the relevance of genetic mutations and the ncRNA-based epigenetic alterations to CRC pathogenesis to help overcome chemoresistance.

Unraveling and targeting RAS-driven metabolic signaling for therapeutic gain

RAS mutations are among the most frequent oncogenic drivers observed in human cancers. With a lack of available treatment options, RAS-mutant cancers account for many of the deadliest cancers in the United States. Recent studies established that altered metabolic requirements are a hallmark of cancer, and many of these alterations are driven by aberrant RAS signaling. Specifically, RAS-driven cancers are characterized by upregulated glycolysis, the differential channeling of glycolytic intermediates, upregulated nutrient scavenging pathways such as autophagy and macropinocytosis, and altered glutamine utilization and mitochondrial function. This unique metabolic landscape promotes tumorigenesis, proliferation, survival in nutrient deficient environments and confers resistance to conventional cytotoxic and targeted therapies. Emerging work demonstrates how these dependencies can be therapeutically exploited in vitro and in vivo with many metabolic inhibitors currently in clinical trials. This review aims to outline the unique metabolic requirements induced by aberrant RAS signaling and how these altered dependencies present opportunities for therapeutic intervention.

Extreme value theory as a framework for understanding mutation frequency distribution in cancer genomes

Currently, the population dynamics of preclonal cancer cells before clonal expansion of tumors has not been sufficiently addressed thus far. By focusing on preclonal cancer cell population as a Darwinian evolutionary system, we formulated and analyzed the observed mutation frequency among tumors (MFaT) as a proxy for the hypothesized sequence read frequency and beneficial fitness effect of a cancer driver mutation. Analogous to intestinal crypts, we assumed that sample donor patients are separate culture tanks where proliferating cells follow certain population dynamics described by extreme value theory (EVT). To validate this, we analyzed three large-scale cancer genome datasets, each harboring > 10000 tumor samples and in total involving > 177898 observed mutation sites. We clarified the necessary premises for the application of EVT in the strong selection and weak mutation (SSWM) regime in relation to cancer genome sequences at scale. We also confirmed that the stochastic distribution of MFaT is likely of the Fréchet type, which challenges the well-known Gumbel hypothesis of beneficial fitness effects. Based on statistical data analysis, we demonstrated the potential of EVT as a population genetics framework to understand and explain the stochastic behavior of driver-mutation frequency in cancer genomes as well as its applicability in real cancer genome sequence data.

Immunohistochemical Characterisation of GLUT1, MMP3 and NRF2 in Osteosarcoma

Osteosarcoma (OSA) is an aggressive bone malignancy. Unlike many other malignancies, OSA outcomes have not improved in recent decades. One challenge to the development of better diagnostic and therapeutic methods for OSA has been the lack of well characterized experimental model systems. Spontaneous OSA in dogs provides a good model for the disease seen in people and also remains an important veterinary clinical challenge. We recently used RNA sequencing and qRT-PCR to provide a detailed molecular characterization of OSA relative to non-malignant bone in dogs. We identified differential mRNA expression of the solute carrier family 2 member 1 (SLC2A1/GLUT1), matrix metallopeptidase 3 (MMP3) and nuclear factor erythroid 2–related factor 2 (NFE2L2/NRF2) genes in canine OSA tissue in comparison to paired non-tumor tissue. Our present work characterizes protein expression of GLUT1, MMP3 and NRF2 using immunohistochemistry. As these proteins affect key processes such as Wnt activation, heme biosynthesis, glucose transport, understanding their expression and the enriched pathways and gene ontologies enables us to further understand the potential molecular pathways and mechanisms involved in OSA. This study further supports spontaneous OSA in dogs as a model system to inform the development of new methods to diagnose and treat OSA in both dogs and people.

Metabolism-associated genes in occurrence and development of gastrointestinal cancer: Latest progress and future prospect

Gastrointestinal (GI) cancer remains one of the most prevalent cancers in the world. The occurrence and progression of GI cancer involve multiple events. Metabolic reprogramming is one of the hallmarks of cancer and is intricately related to tumorigenesis. Many metabolic genes are involved in the occurrence and development of GI cancer. Research approaches combining tumor genomics and metabolomics are more likely to provide deeper insights into this field. In this paper, we review the roles of metabolism-associated genes, especially those involved in the regulation pathways, in the occurrence and progression of GI cancer. We provide the latest progress and future prospect into the different molecular mechanisms of metabolism-associated genes involved in the occurrence and development of GI cancer.

Harness the functions of gut microbiome in tumorigenesis for cancer treatment

It has been shown that gut microbiota dysbiosis leads to physiological changes and links to a number of diseases, including cancers. Thus, many cancer categories and treatment regimens should be investigated in the context of the microbiome. Owing to the availability of metagenome sequencing and multiomics studies, analyses of species characterization, host genetic changes, and metabolic profile of gut microbiota have become feasible, which has facilitated an exponential knowledge gain about microbiota composition, taxonomic alterations, and host interactions during tumorigenesis. However, the complexity of the gut microbiota, with a plethora of uncharacterized host‐microbe, microbe‐microbe, and environmental interactions, still contributes to the challenge of advancing our knowledge of the microbiota‐cancer interactions. These interactions manifest in signaling relay, metabolism, immunity, tumor development, genetic instability, sensitivity to cancer chemotherapy and immunotherapy. This review summarizes current studies/molecular mechanisms regarding the association between the gut microbiota and the development of cancers, which provides insights into the therapeutic strategies that could be harnessed for cancer diagnosis, treatment, or prevention.

Mutant KRAS Downregulates the Receptor for Leukemia Inhibitory Factor (LIF) to Enhance a Signature of Glycolysis in Pancreatic Cancer and Lung Cancer

Pancreatic cancer is characterized by aberrant activity of oncogenic KRAS, which is mutated in 90% of pancreatic adenocarcinomas. Because KRAS itself is a challenging therapeutic target, we focused on understanding key signaling pathways driven by KRAS as a way to reveal dependencies that are amenable to therapeutic intervention. Analyses in primary human pancreatic cancers and model systems revealed that the receptor for the cytokine leukemia inhibitory factor (LIF) is downregulated by mutant KRAS. Furthermore, downregulation of the LIF receptor (LIFR) is necessary for KRAS-mediated neoplastic transformation. We found LIFR exerts inhibitory effects on KRAS-mediated transformation by inhibiting expression of the glucose transporter GLUT1, a key mediator of the enhanced glycolysis found in KRAS-driven malignancies. Decreased LIFR expression leads to increased GLUT1 as well as increases in glycolysis and mitochondrial respiration. The repression of GLUT1 by LIFR is mediated by the transcription factor STAT3, indicating a tumor-suppressive role for STAT3 within cancer cells with mutated KRAS. Finally, reflecting a clinically important tumor-suppressive role of LIFR, decreased LIFR expression correlates with shorter survival in pancreatic cancer patients with mutated KRAS. Similar findings were found in non-small cell lung cancers driven by mutated KRAS, suggesting that silencing LIFR is a generalized mechanism of KRAS-mediated cellular transformation. These results indicate that the LIFR/STAT3 pathway may mediate either tumor-promoting or tumor-suppressive signaling pathways depending on the genetic background of tumor cells, and may play diverse roles within other cells in the tumor microenvironment. IMPLICATIONS: Mutant KRAS drives downregulation of the receptor for LIF, thereby allowing an increase in expression of the glucose transporter GLUT1 and increases in glycolysis and mitochondrial respiration.

Metabolic networks in mutant KRAS-driven tumours: tissue specificities and the microenvironment

Oncogenic mutations in KRAS drive common metabolic programmes that facilitate tumour survival, growth and immune evasion in colorectal carcinoma, non-small-cell lung cancer and pancreatic ductal adenocarcinoma. However, the impacts of mutant KRAS signalling on malignant cell programmes and tumour properties are also dictated by tumour suppressor losses and physiological features specific to the cell and tissue of origin. Here we review convergent and disparate metabolic networks regulated by oncogenic mutant KRAS in colon, lung and pancreas tumours, with an emphasis on co-occurring mutations and the role of the tumour microenvironment. Furthermore, we explore how these networks can be exploited for therapeutic gain.

Understanding the Therapeutic Potential of Ascorbic Acid in the Battle to Overcome Cancer

Cancer, a fatal disease, is also one of the main causes of death worldwide. Despite various developments to prevent and treat cancer, the side effects of anticancer drugs remain a major concern. Ascorbic acid is an essential vitamin required by our bodies for normal physiological function and also has antioxidant and anticancer activity. Although the body cannot synthesize ascorbic acid, it is abundant in nature through foods and other natural sources and also exists as a nutritional food supplement. In anticancer drug development, ascorbic acid has played an important role by inhibiting the development of cancer through various mechanisms, including scavenging reactive oxygen species (ROS), selectively producing ROS and encouraging their cytotoxicity against tumour cells, preventing glucose metabolism, serving as an epigenetic regulator, and regulating the expression of HIF in tumour cells. Several ascorbic acid analogues have been produced to date for their anticancer and antioxidant activity. The current review summarizes the mechanisms behind ascorbic acid's antitumor activity, presents a compilation of its derivatives and their biological activity as anticancer agents, and discusses delivery systems such as liposomes, nanoparticles against cancer, and patents on ascorbic acid as anticancer agents.

Metabolic Strategies for Inhibiting Cancer Development

The tumor microenvironment is a complex mix of cancerous and noncancerous cells (especially immune cells and fibroblasts) with distinct metabolisms. These cells interact with each other and are influenced by the metabolic disorders of the host. In this review, we discuss how metabolic pathways that sustain biosynthesis in cancer cells could be targeted to increase the effectiveness of cancer therapies by limiting the nutrient uptake of the cell, inactivating metabolic enzymes (key regulatory ones or those linked to cell cycle progression), and inhibiting ATP production to induce cell death. Furthermore, we describe how the microenvironment could be targeted to activate the immune response by redirecting nutrients toward cytotoxic immune cells or inhibiting the release of waste products by cancer cells that stimulate immunosuppressive cells. We also examine metabolic disorders in the host that could be targeted to inhibit cancer development. To create future personalized therapies for targeting each cancer tumor, novel techniques must be developed, such as new tracers for positron emission tomography/computed tomography scan and immunohistochemical markers to characterize the metabolic phenotype of cancer cells and their microenvironment. Pending personalized strategies that specifically target all metabolic components of cancer development in a patient, simple metabolic interventions could be tested in clinical trials in combination with standard cancer therapies, such as short cycles of fasting or the administration of sodium citrate or weakly toxic compounds (such as curcumin, metformin, lipoic acid) that target autophagy and biosynthetic or signaling pathways.

The Importance of Being PI3K in the RAS Signaling Network

Ras proteins are essential mediators of a multitude of cellular processes, and its deregulation is frequently associated with cancer appearance, progression, and metastasis. Ras-driven cancers are usually aggressive and difficult to treat. Although the recent Food and Drug Administration (FDA) approval of the first Ras G12C inhibitor is an important milestone, only a small percentage of patients will benefit from it. A better understanding of the context in which Ras operates in different tumor types and the outcomes mediated by each effector pathway may help to identify additional strategies and targets to treat Ras-driven tumors. Evidence emerging in recent years suggests that both oncogenic Ras signaling in tumor cells and non-oncogenic Ras signaling in stromal cells play an essential role in cancer. PI3K is one of the main Ras effectors, regulating important cellular processes such as cell viability or resistance to therapy or angiogenesis upon oncogenic Ras activation. In this review, we will summarize recent advances in the understanding of Ras-dependent activation of PI3K both in physiological conditions and cancer, with a focus on how this signaling pathway contributes to the formation of a tumor stroma that promotes tumor cell proliferation, migration, and spread.

Potential Therapies Targeting Metabolic Pathways in Cancer Stem Cells

Cancer stem cells (CSCs) are heterogeneous cells with stem cell-like properties that are responsible for therapeutic resistance, recurrence, and metastasis, and are the major cause for cancer treatment failure. Since CSCs have distinct metabolic characteristics that plays an important role in cancer development and progression, targeting metabolic pathways of CSCs appears to be a promising therapeutic approach for cancer treatment. Here we classify and discuss the unique metabolisms that CSCs rely on for energy production and survival, including mitochondrial respiration, glycolysis, glutaminolysis, and fatty acid metabolism. Because of metabolic plasticity, CSCs can switch between these metabolisms to acquire energy for tumor progression in different microenvironments compare to the rest of tumor bulk. Thus, we highlight the specific conditions and factors that promote or suppress CSCs properties to portray distinct metabolic phenotypes that attribute to CSCs in common cancers. Identification and characterization of the features in these metabolisms can offer new anticancer opportunities and improve the prognosis of cancer. However, the therapeutic window of metabolic inhibitors used alone or in combination may be rather narrow due to cytotoxicity to normal cells. In this review, we present current findings of potential targets in these four metabolic pathways for the development of more effective and alternative strategies to eradicate CSCs and treat cancer more effectively in the future.

Potential Therapies Targeting Metabolic Pathways in Cancer Stem Cells

Cancer stem cells (CSCs) are heterogeneous cells with stem cell-like properties that are responsible for therapeutic resistance, recurrence, and metastasis, and are the major cause for cancer treatment failure. Since CSCs have distinct metabolic characteristics that plays an important role in cancer development and progression, targeting metabolic pathways of CSCs appears to be a promising therapeutic approach for cancer treatment. Here we classify and discuss the unique metabolisms that CSCs rely on for energy production and survival, including mitochondrial respiration, glycolysis, glutaminolysis, and fatty acid metabolism. Because of metabolic plasticity, CSCs can switch between these metabolisms to acquire energy for tumor progression in different microenvironments compare to the rest of tumor bulk. Thus, we highlight the specific conditions and factors that promote or suppress CSCs properties to portray distinct metabolic phenotypes that attribute to CSCs in common cancers. Identification and characterization of the features in these metabolisms can offer new anticancer opportunities and improve the prognosis of cancer. However, the therapeutic window of metabolic inhibitors used alone or in combination may be rather narrow due to cytotoxicity to normal cells. In this review, we present current findings of potential targets in these four metabolic pathways for the development of more effective and alternative strategies to eradicate CSCs and treat cancer more effectively in the future.

Common and mutation specific phenotypes of KRAS and BRAF mutations in colorectal cancer cells revealed by integrative -omics analysis

BACKGROUND

Genes in the Ras pathway have somatic mutations in at least 60 % of colorectal cancers. Despite activating the same pathway, the BRAF V600E mutation and the prevalent mutations in codon 12 and 13 of KRAS have all been linked to different clinical outcomes, but the molecular mechanisms behind these differences largely remain to be clarified.

METHODS

To characterize the similarities and differences between common activating KRAS mutations and between KRAS and BRAF mutations, we used genome editing to engineer KRAS G12C/D/V and G13D mutations in colorectal cancer cells that had their mutant BRAF V600E allele removed and subjected them to transcriptome sequencing, global proteomics and metabolomics analyses.

RESULTS

By intersecting differentially expressed genes, proteins and metabolites, we uncovered (i) two-fold more regulated genes and proteins when comparing KRAS to BRAF mutant cells to those lacking Ras pathway mutation, (ii) five differentially expressed proteins in KRAS mutants compared to cells lacking Ras pathway mutation (IFI16, S100A10, CD44, GLRX and AHNAK2) and 6 (CRABP2, FLNA, NXN, LCP1, S100A10 and S100A2) compared to BRAF mutant cells, (iii) 19 proteins expressed differentially in a KRAS mutation specific manner versus BRAF V600E cells, (iv) regulation of the Integrin Linked Kinase pathway by KRAS but not BRAF mutation, (v) regulation of amino acid metabolism, particularly of the tyrosine, histidine, arginine and proline pathways, the urea cycle and purine metabolism by Ras pathway mutations, (vi) increased free carnitine in KRAS and BRAF mutant RKO cells.

CONCLUSIONS

This comprehensive integrative -omics analysis confirms known and adds novel genes, proteins and metabolic pathways regulated by mutant KRAS and BRAF signaling in colorectal cancer. The results from the new model systems presented here can inform future development of diagnostic and therapeutic approaches targeting tumors with KRAS and BRAF mutations.

Study of DYRK1B gene expression and its association with metabolic syndrome in a small cohort of Egyptians

BACKGROUND

A cluster of many risk factors for type 2 diabetes and cardiovascular disease is used to describe the metabolic syndrome (MetS). Moreover, genetic differences associated with metabolic syndrome play a key role in its prevalence and side effects. This study aims to investigate the expression of DYRK1B and its association with metabolic syndrome in a small cohort of Egyptian.

MATERIALS AND METHODS

A total of 100 adult Egyptians (50 with MetS and 50 healthy control subjects) were included to this study. Clinical, biochemical and anthropometric analysis were assessed. Relative gene expressions of DYRK1B were compared between two groups of subjects using real time PCR.

RESULTS

We observed marked overexpression in DYRK1B (p < 0.05) in MetS subjects when compared with the healthy control subjects.

CONCLUSION

This is the first study to provide evidence that DYRK1B is highly expressed among the MetS subjects.

Plasma miRNA Biomarkers in Limited Volume Samples for Detection of Early-stage Pancreatic Cancer

Early detection of pancreatic ductal adenocarcinoma (PDAC) is key to improving patient outcomes; however, PDAC is usually diagnosed late. Therefore, blood-based minimally invasive biomarker assays for limited volume clinical samples are urgently needed. A novel miRNA profiling platform (Abcam Fireplex-Oncology Panel) was used to investigate the feasibility of developing early detection miRNA biomarkers with 20 μL plasma from a training set (58 stage II PDAC cases and 30 controls) and two validation sets (34 stage II PDAC cases and 25 controls; 44 stage II PDAC cases and 18 controls). miR-34a-5p [AUC = 0.77; 95% confidence interval (CI), 0.66-0.87], miR-130a-3p (AUC = 0.74; 95% CI, 0.63-0.84), and miR-222-3p (AUC = 0.70; 95% CI, 0.58-0.81) were identified as significantly differentially abundant in plasma from stage II PDAC versus controls. Although none of the miRNAs individually outperformed the currently used serologic biomarker for PDAC, carbohydrate antigen 19-9 (CA19-9), combining the miRNAs with CA 19-9 improved AUCs from 0.89 (95% CI, 0.81-0.95) for CA 19-9 alone to 0.92 (95% CI, 0.86-0.97), 0.94 (95% CI, 0.89-0.98), and 0.92 (95% CI, 0.87-0.97), respectively. Gene set enrichment analyses of transcripts correlated with high and low expression of the three miRNAs in The Cancer Genome Atlas PDAC sample set. These miRNA biomarkers, assayed in limited volume plasma together with CA19-9, discriminate stage II PDAC from controls with good sensitivity and specificity. Unbiased profiling of larger cohorts should help develop an informative early detection biomarker assay for diagnostic settings. PREVENTION RELEVANCE: Development of minimally invasive biomarker assays for detection of premalignant disease and early-stage pancreatic cancer is key to improving patient survival. This study describes a limited volume plasma miRNA biomarker assay that can detect early-stage resectable pancreatic cancer in clinical samples necessary for effective prevention and clinical intervention.

Development of a novel multi-functional integrated bioconjugate that effectively targets K-Ras mutant pancreatic cancer

Folate receptor (FR) overexpression occurs in a variety of cancers, including pancreatic cancer. In addition, enhanced macropinocytosis exists in K-Ras mutant pancreatic cancer. Furthermore, the occurrence of intensive desmoplasia causes a hypoxic microenvironment in pancreatic cancer. In this study, a novel FR-directed, macropinocytosis-enhanced, and highly cytotoxic bioconjugate folate (F)-human serum albumin (HSA)-apoprotein of lidamycin (LDP)-active enediyne (AE) derived from lidamycin was designed and prepared. F-HSA-LDP-AE consisted of four moieties: F, HSA, LDP, and AE. F-HSA-LDP presented high binding efficiency with the FR and pancreatic cancer cells. Its uptake in wild-type cells was more extensive than in K-Ras mutant-type cells. By in vivo optical imaging, F-HSA-LDP displayed prominent tumor-specific biodistribution in pancreatic cancer xenograft-bearing mice, showing clear and lasting tumor localization for 360 h. In the MTT assay, F-HSA-LDP-AE demonstrated potent cytotoxicity in three types of pancreatic cancer cell lines. It also induced apoptosis and caused G2/M cell cycle arrest. F-HSA-LDP-AE markedly suppressed the tumor growth of AsPc-1 pancreatic cancer xenografts in athymic mice. At well-tolerated doses of 0.5 and 1 mg/kg, (i.v., twice), the inhibition rates were 91.2% and 94.8%, respectively (P<0.01). The results of this study indicate that the F-HSA-LDP multi-functional bioconjugate might be effective for treating K-Ras mutant pancreatic cancer.

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We designed and generated a folate receptor-targeted and macropinocytosis-enhanced recombinant protein conjugate.

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F-HSA-LDP displayed highly specific biodistribution and long-lasting tumor accumulation in pancreatic cancer cells.

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F-HSA-LDP-AE induced apoptosis and G2/M cell cycle arrest and markedly suppressed the growth of pancreatic cancer cells.

Pretreatment 18F-FDG PET/CT Imaging Predicts the KRAS/NRAS/BRAF Gene Mutational Status in Colorectal Cancer

Objective

To investigate the association between KRAS/NRAS/BRAF mutations and metabolic parameters of pretreatment ¹⁸F-FDG PET/CT in colorectal cancer (CRC).

Methods

A total of 85 patients with CRC were included in the study. PET/CT was performed in all the patients before surgery. The histopathological examination and analysis of the gene mutational status of the primary tumor were conducted. The associations among clinical features, PET metabolic parameters, and the gene mutational status were investigated. Moreover, receiver operating characteristic (ROC) curves for maximum standard uptake value (SUVmax) of the primary tumor were generated along with analysis of the target tissue to nontarget tissue ratio (T/NT) for predicting the efficacy of KRAS/NRAS/BRAF mutations in CRC. Finally, the corresponding area under the curve, the optimal cutoff value, and the corresponding sensitivity and specificity were obtained.

Results

The mutation rate of KRAS/NRAS/BRAF was 54.12% (46/85). In addition, both SUVmax and T/NT were significantly higher in the KRAS/NRAS/BRAF-mutation groups compared to the wild-type group (15.88 ± 6.71 vs. 12.59 ± 5.79, 8.04 ± 3.03 vs. 6.38 ± 2.80; P=0.012 and 0.004, respectively). Results from the ROC curve also showed that the cutoff values for T/NT and SUVmax were 5.14 and 12.40, respectively, while the predictive accuracy was 0.682 and 0.647, respectively. On the other hand, the sensitivity was 91.30% and 65.22% while the specificity was 43.59% and 64.10%, respectively. Moreover, univariate analysis showed that the KRAS/NRAS/BRAF mutation was not significantly associated with gender, age, lesion location, tumor length, pathological type, tissue differentiation, and UICC staging (all P > 0.05).

Conclusion

T/NT ratio and SUVmax could be the potential surrogate imaging indicators to predict the KRAS/NRAS/BRAF mutational status in CRC patients.

Metabolic Reprogramming of Colorectal Cancer Cells and the Microenvironment: Implication for Therapy

Colorectal carcinoma (CRC) is one of the most frequently diagnosed carcinomas and one of the leading causes of cancer-related death worldwide. Metabolic reprogramming, a hallmark of cancer, is closely related to the initiation and progression of carcinomas, including CRC. Accumulating evidence shows that activation of oncogenic pathways and loss of tumor suppressor genes regulate the metabolic reprogramming that is mainly involved in glycolysis, glutaminolysis, one-carbon metabolism and lipid metabolism. The abnormal metabolic program provides tumor cells with abundant energy, nutrients and redox requirements to support their malignant growth and metastasis, which is accompanied by impaired metabolic flexibility in the tumor microenvironment (TME) and dysbiosis of the gut microbiota. The metabolic crosstalk between the tumor cells, the components of the TME and the intestinal microbiota further facilitates CRC cell proliferation, invasion and metastasis and leads to therapy resistance. Hence, to target the dysregulated tumor metabolism, the TME and the gut microbiota, novel preventive and therapeutic applications are required. In this review, the dysregulation of metabolic programs, molecular pathways, the TME and the intestinal microbiota in CRC is addressed. Possible therapeutic strategies, including metabolic inhibition and immune therapy in CRC, as well as modulation of the aberrant intestinal microbiota, are discussed.

Glucose deprivation-induced aberrant FUT1-mediated fucosylation drives cancer stemness in hepatocellular carcinoma

Rapidly growing tumors often experience hypoxia and nutrient (e.g., glucose) deficiency because of poor vascularization. Tumor cells respond to the cytotoxic effects of such stresses by inducing molecular adaptations that promote clonal selection of a more malignant tumor-initiating cell phenotype, especially in the innermost tumor regions. Here, we report a regulatory mechanism involving fucosylation by which glucose restriction promotes cancer stemness to drive drug resistance and tumor recurrence. Using hepatocellular carcinoma (HCC) as a model, we showed that restricted glucose availability enhanced the PERK/eIF2α/ATF4 signaling axis to drive fucosyltransferase 1 (FUT1) transcription via direct binding of ATF4 to the FUT1 promoter. FUT1 overexpression is a poor prognostic indicator for HCC. FUT1 inhibition could mitigate tumor initiation, self-renewal, and drug resistance. Mechanistically, we demonstrated that CD147, ICAM-1, EGFR, and EPHA2 are glycoprotein targets of FUT1, in which such fucosylation would consequently converge on deregulated AKT/mTOR/4EBP1 signaling to drive cancer stemness. Treatment with an α-(1,2)-fucosylation inhibitor sensitized HCC tumors to sorafenib, a first-line molecularly targeted drug used for advanced HCC patients, and reduced the tumor-initiating subset. FUT1 overexpression and/or CD147, ICAM-1, EGFR, and EPHA2 fucosylation may be good prognostic markers and therapeutic targets for cancer patients.

Enhanced triacylglycerol catabolism by carboxylesterase 1 promotes aggressive colorectal carcinoma

The ability to adapt to low-nutrient microenvironments is essential for tumor cell survival and progression in solid cancers, such as colorectal carcinoma (CRC). Signaling by the NF-κB transcription factor pathway associates with advanced disease stages and shorter survival in patients with CRC. NF-κB has been shown to drive tumor-promoting inflammation, cancer cell survival, and intestinal epithelial cell (IEC) dedifferentiation in mouse models of CRC. However, whether NF-κB affects the metabolic adaptations that fuel aggressive disease in patients with CRC is unknown. Here, we identified carboxylesterase 1 (CES1) as an essential NF-κB-regulated lipase linking obesity-associated inflammation with fat metabolism and adaptation to energy stress in aggressive CRC. CES1 promoted CRC cell survival via cell-autonomous mechanisms that fuel fatty acid oxidation (FAO) and prevent the toxic build-up of triacylglycerols. We found that elevated CES1 expression correlated with worse outcomes in overweight patients with CRC. Accordingly, NF-κB drove CES1 expression in CRC consensus molecular subtype 4 (CMS4), which is associated with obesity, stemness, and inflammation. CES1 was also upregulated by gene amplifications of its transcriptional regulator HNF4A in CMS2 tumors, reinforcing its clinical relevance as a driver of CRC. This subtype-based distribution and unfavorable prognostic correlation distinguished CES1 from other intracellular triacylglycerol lipases and suggest CES1 could provide a route to treat aggressive CRC.

Dual Mechanisms of Metabolism and Gene Expression of the CCRF-CEM Leukemia Cells under Glucocorticoid Treatment

BACKGROUND

Glucocorticoids play an essential part in anti-leukemic therapies, but resistance is a crucial event for the prognosis of the disease. Glucocorticoids influence the metabolic properties of leukemic cells. The inherent plasticity of clinically evolving cancer cells justifies the characterization of drug-induced early oncogenic pathways, which represent a likely source of detrimental secondary effects.

AIM

The present work aims to investigate the effect of glucocorticoids in metabolic pathways in the CCRF-CEM leukemic cells. Metabolic factors and gene expression profiles were examined in order to unravel the possible mechanisms of the CCRF-CEM leukemic cell growth dynamics.

METHODS

CCRF-CEM cells were used as a model. Cells were treated with prednisolone with concentrations 0-700 μM. Cell culture supernatants were used for glucose, lactic acid, LDH, Na⁺, K⁺ and Ca⁺⁺ measurements. Cytotoxicity was determined with flow cytometry. Microarray analysis was performed using two different chips of 1.2 k and 4.8 k genes. Gene Ontology enrichment analysis was applied to find metabolism- and GC-related genes.

RESULTS

Higher prednisolone concentrations inhibited glucose uptake, without exhibiting any cytotoxic effects. Glucose consumption did not correlate with the total cell population, or the viable population, indicating that growth is not directly proportional to glucose consumption. Neither of the subpopulations, i.e., viable, necrotic, or apoptotic cells, contributed to this.

CONCLUSIONS

Different types of leukemic cells seem to exhibit different patterns of glucose metabolism. Both resistant and sensitive CCRF-CEM cells followed the aerobic pathway of glycolysis. There is probably a rapid change in membrane permeability, causing a general shutdown towards everything that is outside the cell. This could in part also explain the observed resistance. Glucocorticoids do not enter the cell passively anymore and therefore no effects are observed. Based on our observations, ion concentrations are measurable factors both in vitro and in vivo, which makes them possible markers of glucocorticoid cytotoxic action.

The current understanding on the impact of KRAS on colorectal cancer

KRAS (kirsten rat sarcoma viral oncogene) is a member of the RAS family. KRAS mutations are one of most dominant mutations in colorectal cancer (CRC). The impact of KRAS mutations on the prognosis and survival of CRC patients drives many research studies to explore potential therapeutics or target therapy for the KRAS mutant CRC. This review summarizes the current understanding of the pathological consequences of the KRAS mutations in the development of CRC; and the impact of the mutations on the response and the sensitivity to the current front-line chemotherapy. The current therapeutic strategies for treating KRAS mutant CRC, the difficulties and challenges will also be discussed.

The Intricate Metabolism of Pancreatic Cancers

Currently, approximately 95% of pancreatic cancers are pancreatic ductal adenocarcinomas (PDAC), which are the most aggressive form and the fourth leading cause of cancer death with extremely poor prognosis [1]. Poor prognosis is primarily attributed to the late diagnosis of the disease when patients are no longer candidates for surgical resection [2]. Cancer cells are dependent on the oncogenes that allow them to proliferate limitlessly. Thus, targeting the expression of known oncogenes in pancreatic cancer has been shown to lead to more effective treatment [3]. This chapter discusses the complexity of metabolic features in pancreatic cancers. In order to comprehend the heterogeneous nature of cancer metabolism fully, we need to take into account the close relationship between cancer metabolism and genetics. Gene expression varies tremendously, not only among different types of cancers but also within the same type of cancer among different patients. Cancer metabolism heterogeneity is often prompted and perpetuated not only by mutations in oncogenes and tumor-suppressor genes but also by the innate diversity of the tumor microenvironment. Much effort has been focused on elucidating the genetic alterations that correlate with disease progression and treatment response [4, 5]. However, the precise mechanisms by which tumor metabolism contributes to cancer growth, survival, mobility, and aggressiveness represent a functional readout of tumor progression (Fig. 1).

KRAS Mutation Dictates the Cancer Immune Environment in Pancreatic Ductal Adenocarcinoma and Other Adenocarcinomas

Simple Summary

The vast majority of patients with pancreatic ductal adenocarcinomas harbor KRAS mutations in their tumors. Functionally, mutated KRAS is not only dedicated to tumor cell proliferation, survival and invasiveness, but also causing the immunosuppression in this cancer. In this situation, current data indicating the therapeutic effects of immune checkpoint inhibitors on pancreatic ductal adenocarcinomas are still not satisfying. In order to reflect the present bottleneck of immune checkpoint inhibitors in managing this cancer, we mainly provide information associated with the mechanism by which KRAS mutations establish the immunosuppressive milieus in pancreatic ductal adenocarcinomas. Together with other advances in this field, future directions to overcome the KRAS mutation-induced immunosuppression in pancreatic ductal adenocarcinomas are raised as well. Meanwhile, lung adenocarcinomas and colorectal adenocarcinomas are enumerated to compare with pancreatic ductal adenocarcinomas, aiming to indicate the specificity of KRAS mutations in dictating tumoral immune milieus among these cancers.

Abstract

Generally, patients with pancreatic ductal adenocarcinoma, especially those with wide metastatic lesions, have a poor prognosis. Recently, a breakthrough in improving their survival has been achieved by using first-line chemotherapy, such as gemcitabine plus nab-paclitaxel or oxaliplatin plus irinotecan plus 5-fluorouracil plus calcium folinate. Unfortunately, regimens with high effectiveness are still absent in second- or later-line settings. In addition, although immunotherapy using checkpoint inhibitors definitively represents a novel method for metastatic cancers, monotherapy using checkpoint inhibitors is almost completely ineffective for pancreatic ductal adenocarcinomas largely due to the suppressive immune milieu in such tumors. Critically, the genomic alteration pattern is believed to impact cancer immune environment. Surprisingly, KRAS gene mutation is found in almost all pancreatic ductal adenocarcinomas. Moreover, KRAS mutation is indispensable for pancreatic carcinogenesis. On these bases, a relationship likely exists between this oncogene and immunosuppression in this cancer. During pancreatic carcinogenesis, KRAS mutation-driven events, such as metabolic reprogramming, cell autophagy, and persistent activation of the yes-associated protein pathway, converge to cause immune evasion. However, intriguingly, KRAS mutation can dictate a different immune environment in other types of adenocarcinoma, such as colorectal adenocarcinoma and lung adenocarcinoma. Overall, the KRAS mutation can drive an immunosuppression in pancreatic ductal adenocarcinomas or in colorectal carcinomas, but this mechanism is not true in KRAS-mutant lung adenocarcinomas, especially in the presence of TP53 inactivation. As a result, the response of these adenocarcinomas to checkpoint inhibitors will vary.

The harsh microenvironment in early breast cancer selects for a Warburg phenotype

Glucose is converted to energy through “fermentation” or “oxidation.” Generally, if oxygen is available, cells will oxidize glucose to CO₂ because it is more efficient than fermentation, which produces lactic acid. But Warburg noted that cancers ferment glucose at a “remarkable” rate even if O₂ is available! This “Warburg Effect” is still misunderstood because it doesn’t make sense that a cell would ferment glucose when it could get much more energy by oxidizing it. The current paper goes to the heart of this problem by defining the microenvironmental conditions that exist in early cancers that would select for a Warburg Effect. This is important because such cells are much more aggressive and like to lead to cancers that are lethal.

The harsh microenvironment of ductal carcinoma in situ (DCIS) exerts strong evolutionary selection pressures on cancer cells. We hypothesize that the poor metabolic conditions near the ductal center foment the emergence of a Warburg Effect (WE) phenotype, wherein cells rapidly ferment glucose to lactic acid, even in normoxia. To test this hypothesis, we subjected low-glycolytic breast cancer cells to different microenvironmental selection pressures using combinations of hypoxia, acidosis, low glucose, and starvation for many months and isolated single clones for metabolic and transcriptomic profiling. The two harshest conditions selected for constitutively expressed WE phenotypes. RNA sequencing analysis of WE clones identified the transcription factor KLF4 as potential inducer of the WE phenotype. In stained DCIS samples, KLF4 expression was enriched in the area with the harshest microenvironmental conditions. We simulated in vivo DCIS phenotypic evolution using a mathematical model calibrated from the in vitro results. The WE phenotype emerged in the poor metabolic conditions near the necrotic core. We propose that harsh microenvironments within DCIS select for a WE phenotype through constitutive transcriptional reprogramming, thus conferring a survival advantage and facilitating further growth and invasion.

Specific activation of glycolytic enzyme enolase 2 in BRAF V600E-mutated colorectal cancer

The BRAF V600E mutation occurs in approximately 10% of patients with metastatic colorectal cancer (CRC) and constitutes a distinct subtype of the disease with extremely poor prognosis. To address this refractory disease, we investigated the unique metabolic gene profile of BRAF V600E‐mutated tumors via in silico analysis using a large‐scale clinical database. We found that BRAF V600E‐mutated tumors exhibited a specific metabolic gene expression signature, including some genes that are associated with poor prognosis in CRC. We discovered that BRAF V600E‐mutated tumors expressed high levels of glycolytic enzyme enolase 2 (ENO2), which is mainly expressed in neuronal tissues under physiological conditions. In vitro experiments using CRC cells demonstrated that BRAF V600E‐mutated cells exhibited enhanced dependency on ENO2 compared to BRAF wild‐type cancer cells and that knockdown of ENO2 led to the inhibition of proliferation and migration of BRAF V600E‐mutated cancer cells. Moreover, inhibition of ENO2 resulted in enhanced sensitivity to vemurafenib, a selective inhibitor of BRAF V600E. We identified AP‐1 transcription factor subunit (FOSL1) as being involved in the transcription of ENO2 in CRC cells. In addition, both MAPK and PI3K/Akt signaling were suppressed upon inhibition of ENO2, implying an additional oncogenic role of ENO2. These results suggest the crucial role of ENO2 in the progression of BRAF V600E‐mutated CRC and indicate the therapeutic implications of targeting this gene.

Restricting Glutamine Uptake Enhances NSCLC Sensitivity to Third-Generation EGFR-TKI Almonertinib

The emergence of secondary resistance is the main failure cause of epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) as a targeted therapy for non-small cell lung cancer (NSCLC). EGFR mutations of NSCLC cells can markedly increase glutamine transporter (SLC1A5) expression, thereby increasing glutamine metabolism. Glutamine metabolites can activate EGFR downstream signals, including mTOR, ERK1/2, STAT3, etc., which is an important cause for the decreased sensitivity of NSCLC to EGFR-TKIs. CCK8 and Annexin V/PI assays were conducted to detect the effects of Almonertinib and/or V9302 on the proliferation and apoptosis of NSCLC cells. Proteomics was used to determine the effect of Almonertinib on energy metabolism-related proteins in NSCLC. siRNA transfection was performed to study the effect of SLC1A5 down-regulation on cell proliferation. In addition, the effects of drugs on colony formation capacity were determined by colony formation assay. Immunofluorescence and Western blot were utilized to detect the apoptosis- and autophagy-related proteins expression. DAPI staining was utilized to detect the effect of drugs on the nucleus. Transmission electron microscope was used to observe the changes of submicroscopic structure such as autophagosomes and nucleus of cells. mCherry-GFP-LC3B tandem fluorescent protein was to used to detect the level of autophagy flux. Tumor-bearing nude mouse model was utilized to detect the effect of V9302 on the anti-tumor effect of Almonertinib in vivo. As a result, Almonertinib suppressed H1975 and A549 cell proliferation depended on its dosage and treatment duration, and it also induced apoptosis. A549 cells with wild-type EGFR had lower sensitivity to Almonertinib. The expression of SLC1A5 was up-regulated by stimulating with low concentration of Almonertinib in NSCLC cells. SLC1A5 was highly expressed in A549 cells with wild-type EGFR. Glutamine deletion or SLC1A5 inhibition/silencing inhibited the proliferation of NSCLC cells, and decreased cellular glutamine uptake. The combination of SLC1A5 inhibitor V9302 and Almonertinib had a synergistic inhibitory effect on the proliferation of NSCLC. V9302 enhanced the effect of Almonertinib in apoptosis-inducing in NSCLC cells. The combination of V9302 and Almonertinib might induce apoptosis by inhibiting autophagy.

Moonlighting Metabolic Enzymes in Cancer: New Perspectives on the Redox Code

Significance: Metabolic reprogramming is considered to be a critical adaptive biological event that fulfills the energy and biomass demands for cancer cells. One hallmark of metabolic reprogramming is reduced oxidative phosphorylation and enhanced aerobic glycolysis. Such metabolic abnormalities contribute to the accumulation of reactive oxygen species (ROS), the by-products of metabolic pathways. Emerging evidence suggests that ROS can in turn directly or indirectly affect the expression, activity, or subcellular localization of metabolic enzymes, contributing to the moonlighting functions outside of their primary roles. This review summarizes the multifunctions of metabolic enzymes and the involved redox modification patterns, which further reveal the inherent connection between metabolism and cellular redox state. Recent Advances: These noncanonical functions of metabolic enzymes involve the regulation of epigenetic modifications, gene transcription, post-translational modification, cellular antioxidant capacity, and many other fundamental cellular events. The multifunctional properties of metabolic enzymes further expand the metabolic dependencies of cancer cells, and confer cancer cells with a means of adapting to diverse environmental stimuli. Critical Issues: Deciphering the redox-manipulated mechanisms with specific emphasis on the moonlighting function of metabolic enzymes is important for clarifying the pertinence between metabolism and redox processes. Future Directions: Investigation of the redox-regulated moonlighting functions of metabolic enzymes will shed new lights into the mechanism by which metabolic enzymes gain noncanonical functions, and yield new insights into the development of novel therapeutic strategies for cancer treatment by targeting metabolic-redox abnormalities. Antioxid. Redox Signal. 34, 979-1003.

Therapeutic Approach of KRAS Mutant Tumours by the Combination of Pharmacologic Ascorbate and Chloroquine

The Warburg effect has been considered a potential therapeutic target to fight against cancer progression. In KRAS mutant cells, PKM2 (pyruvate kinase isozyme M2) is hyper-activated, and it induces GLUT1 expression; therefore, KRAS has been closely involved in the initiation of Warburg metabolism. Although mTOR (mammalian target of rapamycin), a well-known inhibitor of autophagy-dependent survival in physiological conditions, is also activated in KRAS mutants, many recent studies have revealed that autophagy becomes hyper-active in KRAS mutant cancer cells. In the present study, a mathematical model was built containing the main elements of the regulatory network in KRAS mutant cancer cells to explore the further possible therapeutic strategies. Our dynamical analysis suggests that the downregulation of KRAS, mTOR and autophagy are crucial in anti-cancer therapy. PKM2 has been assumed to be the key switch in the stress response mechanism. We predicted that the addition of both pharmacologic ascorbate and chloroquine is able to block both KRAS and mTOR pathways: in this case, no GLUT1 expression is observed, meanwhile autophagy, essential for KRAS mutant cancer cells, is blocked. Corresponding to our system biological analysis, this combined pharmacologic ascorbate and chloroquine treatment in KRAS mutant cancers might be a therapeutic approach in anti-cancer therapies.

Targeting lactate dehydrogenase a improves radiotherapy efficacy in non-small cell lung cancer: from bedside to bench

BACKGROUND

Lactate dehydrogenase A (LDHA) is overexpressed and associated with poor prognosis in many kinds of cancer. In the current study, we evaluated the prognostic value of LDHA expression in non-small cell lung cancer (NSCLC), and tested whether LDHA inhibition might improve radiotherapy efficacy in NSCLC.

METHODS

LDHA expression was investigated in NSCLC patients, using online database and further verified by immunohistochemistry. The prognostic value of LDHA was evaluated using Kaplan-Meier plotter database. In vitro, two NSCLC cell lines were pretreated with oxamate, an inhibitor of LDHA, and colony formation method was performed to determine cellular radiosensitivity. Comet assay was used to detect DNA damage after irradiation. Flow cytometry was applied to test cell cycle progression and apoptosis, and monodansylcadaverine (MDC) staining was used to examine cell autophagy.

RESULTS

Both mRNA and protein levels of LDHA expression were up-regulated in NSCLC tissues. High LDHA expression was a poor prognostic factor and associated with radioresistance in NSCLC patients. LDHA inhibition by oxamate remarkably increased radiosensitivity in both A549 and H1975 cancer cells, and enhanced ionizing radiation (IR)-induced apoptosis and autophagy, accompanied by cell cycle distribution alternations. Furthermore, LDHA inhibition induced reactive oxygen species (ROS) accumulation and cellular ATP depletion, which might increase DNA injury and hinder DNA repair activity.

CONCLUSIONS

Our study suggests that inhibition of LDHA may be a potential strategy to improve radiotherapy efficacy in NSCLC patients, which needs to be further tested by clinical trials.

Interplay between Metabolism Reprogramming and Epithelial-to-Mesenchymal Transition in Cancer Stem Cells

Simple Summary

Tumor cells display important plasticity potential. Notably, tumor cells have the ability to change toward immature cells called cancer stem cells under the influence of the tumor environment. Importantly, cancer stem cells are a small subset of relatively quiescent cells that, unlike rapidly dividing differentiated tumor cells, escape standard chemotherapies, causing relapse or recurrence of cancer. Interestingly, these cells adopt a specific metabolism. Most often, they mainly rely on glucose uptake and metabolism to sustain their energy needs. This metabolic reprogramming is set off by environmental factors such as pro-inflammatory signals or catecholamine hormones (epinephrine, norepinephrine). A better understanding of this process could provide opportunities to kill cancer stem cells. Indeed, it would become possible to develop drugs that act specifically on metabolic pathways used by these cells. These new drugs could be used to strengthen the effects of current chemotherapies and overcome cancers with poor prognoses.

Abstract

Tumor cells display important plasticity potential, which contributes to intratumoral heterogeneity. Notably, tumor cells have the ability to retrodifferentiate toward immature states under the influence of their microenvironment. Importantly, this phenotypical conversion is paralleled by a metabolic rewiring, and according to the metabostemness theory, metabolic reprogramming represents the first step of epithelial-to-mesenchymal transition (EMT) and acquisition of stemness features. Most cancer stem cells (CSC) adopt a glycolytic phenotype even though cells retain functional mitochondria. Such adaptation is suggested to reduce the production of reactive oxygen species (ROS), protecting CSC from detrimental effects of ROS. CSC may also rely on glutaminolysis or fatty acid metabolism to sustain their energy needs. Besides pro-inflammatory cytokines that are well-known to initiate the retrodifferentiation process, the release of catecholamines in the microenvironment of the tumor can modulate both EMT and metabolic changes in cancer cells through the activation of EMT transcription factors (ZEB1, Snail, or Slug (SNAI2)). Importantly, the acquisition of stem cell properties favors the resistance to standard care chemotherapies. Hence, a better understanding of this process could pave the way for the development of therapies targeting CSC metabolism, providing new strategies to eradicate the whole tumor mass in cancers with unmet needs.

GLUT5 (SLC2A5) enables fructose-mediated proliferation independent of ketohexokinase

BACKGROUND

Fructose is an abundant source of carbon and energy for cells to use for metabolism, but only certain cell types use fructose to proliferate. Tumor cells that acquire the ability to metabolize fructose have a fitness advantage over their neighboring cells, but the proteins that mediate fructose metabolism in this context are unknown. Here, we investigated the determinants of fructose-mediated cell proliferation.

METHODS

Live cell imaging and crystal violet assays were used to characterize the ability of several cell lines (RKO, H508, HepG2, Huh7, HEK293T (293T), A172, U118-MG, U87, MCF-7, MDA-MB-468, PC3, DLD1 HCT116, and 22RV1) to proliferate in fructose (i.e., the fructolytic ability). Fructose metabolism gene expression was determined by RT-qPCR and western blot for each cell line. A positive selection approach was used to "train" non-fructolytic PC3 cells to utilize fructose for proliferation. RNA-seq was performed on parental and trained PC3 cells to find key transcripts associated with fructolytic ability. A CRISPR-cas9 plasmid containing KHK-specific sgRNA was transfected in 293T cells to generate KHK-/- cells. Lentiviral transduction was used to overexpress empty vector, KHK, or GLUT5 in cells. Metabolic profiling was done with seahorse metabolic flux analysis as well as LC/MS metabolomics. Cell Titer Glo was used to determine cell sensitivity to 2-deoxyglucose in media containing either fructose or glucose.

RESULTS

We found that neither the tissue of origin nor expression level of any single gene related to fructose catabolism determine the fructolytic ability. However, cells cultured chronically in fructose can develop fructolytic ability. SLC2A5, encoding the fructose transporter, GLUT5, was specifically upregulated in these cells. Overexpression of GLUT5 in non-fructolytic cells enabled growth in fructose-containing media across cells of different origins. GLUT5 permitted fructose to flux through glycolysis using hexokinase (HK) and not ketohexokinase (KHK).

CONCLUSIONS

We show that GLUT5 is a robust and generalizable driver of fructose-dependent cell proliferation. This indicates that fructose uptake is the limiting factor for fructose-mediated cell proliferation. We further demonstrate that cellular proliferation with fructose is independent of KHK.

Targeting KRAS: The Elephant in the Room of Epithelial Cancers

Mutations of the proto-oncogene KRAS are the most frequent gain-of-function alterations found in cancer. KRAS is mutated in about 30% of all human tumors, but it could reach more than 90% in certain cancer types such as pancreatic adenocarcinoma. Although historically considered to be undruggable, a particular KRAS mutation, the G12C variant, has recently emerged as an actionable alteration especially in non-small cell lung cancer (NSCLC). KRASG12C and pan-KRAS inhibitors are being tested in clinical trials and have recently shown promising activity. Due to the difficulties in direct targeting of KRAS, other approaches are being explored. The inhibition of target upstream activators or downstream effectors of KRAS pathway has shown to be moderately effective given the evidence of emerging mechanisms of resistance. Various synthetic lethal partners of KRAS have recently being identified and the inhibition of some of those might prove to be successful in the future. The study of escape mechanisms to KRAS inhibition could support the utility of combination strategies in overcoming intrinsic and adaptive resistance and enhancing clinical benefit of KRASG12C inhibitors. Considering the role of the microenvironment in influencing tumor initiation and promotion, the immune tumor niche of KRAS mutant tumors has been deeply explored and characterized for its unique immunosuppressive skewing. However, a number of aspects remains to be fully understood, and modulating this tumor niche might revert the immunoresistance of KRAS mutant tumors. Synergistic associations of KRASG12C and immune checkpoint inhibitors are being tested.

LncRNA NBR2 aggravates hepatoblastoma cell malignancy and promotes cell proliferation under glucose starvation through the miR-22/TCF7 axis

Hepatoblastoma (HB) is the most commonly seen pediatric liver malignancy. With frequent mutations in CTNNB1 gene that encodes β-catenin, hepatoblastoma has been considered as a Wnt/β-catenin-activated malignant tumor. Altered glucose metabolism upon nutrient deprivation (glucose starvation) might also be a critical event in hepatoblastoma carcinogenesis. The present study provides a lncRNA NBR2/miR-22/TCF7 axis modulating proliferation, invasion, migration, and apoptosis of hepatoblastoma cells upon glucose starvation through Wnt and downstream TCF7 signaling pathways. The expression of NBR2 is significantly increased within hepatoblastoma tissue samples; moreover, under incubation with 0 mM glucose (glucose starvation), NBR2 expression is significantly upregulated. NBR2 silencing not only inhibited hepatoblastoma cell viability, invasion, and migration under normal culture condition but also promoted the cell apoptosis under glucose starvation. NBR2 silencing in hepatoblastoma cells also decreased TCF7 mRNA expression and TCF7 protein levels, as well as the protein levels of the cell cycle, glucose entrapment, and EMT markers. miR-22 is directly bound to both NBR2 and TCF7; lncRNA NBR2 counteracted miR-22-mediated repression on TCF7 via acting as a ceRNA. The effects of NBR2 silencing on TCF7 expression, hepatoblastoma cell phenotype, and cell cycle, glucose entrapment, and EMT markers were all significantly reversed by miR-22 inhibition. In conclusion, lncRNA NBR2 aggravates hepatoblastoma cell malignancy through competing with TCF7 for miR-22 binding, therefore counteracting miR-22-mediated repression on TCF7. LncRNA NBR2 might be a promising target to inhibit hepatoblastoma cell proliferation under glucose starvation.

The Metabolic Landscape of RAS-Driven Cancers from biology to therapy

Our understanding of how the RAS protein family, and in particular mutant KRAS promote metabolic dysregulation in cancer cells has advanced significantly over the last decade. In this Review, we discuss the metabolic reprogramming mediated by oncogenic RAS in cancer, and elucidating the underlying mechanisms could translate to novel therapeutic opportunities to target metabolic vulnerabilities in RAS-driven cancers.

Linking Metabolic Reprogramming, Plasticity and Tumor Progression

Simple Summary

In the present review, we discuss the role of metabolic reprogramming which occurs in malignant cells. The process of metabolic reprogramming is also known as one of the “hallmarks of cancer”. Due to several reasons, including the origin of cancer, tumor microenvironment, and the tumor progression stage, metabolic reprogramming can be heterogeneous and dynamic. In this review, we provide evidence that the usage of metabolic drugs is a promising approach to treat cancer. However, because these drugs can damage not only malignant cells but also normal rapidly dividing cells, it is important to understand the exact metabolic changes which are elicited by particular drivers in concrete tissue and are specific for each stage of cancer development, including metastases. Finally, the review highlights new promising targets for the development of new metabolic drugs.

Abstract

The specific molecular features of cancer cells that distinguish them from the normal ones are denoted as “hallmarks of cancer”. One of the critical hallmarks of cancer is an altered metabolism which provides tumor cells with energy and structural resources necessary for rapid proliferation. The key feature of a cancer-reprogrammed metabolism is its plasticity, allowing cancer cells to better adapt to various conditions and to oppose different therapies. Furthermore, the alterations of metabolic pathways in malignant cells are heterogeneous and are defined by several factors including the tissue of origin, driving mutations, and microenvironment. In the present review, we discuss the key features of metabolic reprogramming and plasticity associated with different stages of tumor, from primary tumors to metastases. We also provide evidence of the successful usage of metabolic drugs in anticancer therapy. Finally, we highlight new promising targets for the development of new metabolic drugs.