The effect of thiamine supplementation on tumour proliferation. A metabolic control analysis study

Managing Undernutrition in Pediatric Oncology: A Consensus Statement Developed Using the Delphi Method by the Polish Society for Clinical Nutrition of Children and the Polish Society of Pediatric Oncology and Hematology

"Managing Undernutrition in Pediatric Oncology" is a collaborative consensus statement of the Polish Society for Clinical Nutrition of Children and the Polish Society of Pediatric Oncology and Hematology. The early identification and accurate management of malnutrition in children receiving anticancer treatment are crucial components to integrate into comprehensive medical care. Given the scarcity of high-quality literature on this topic, a consensus statement process was chosen over other approaches, such as guidelines, to provide comprehensive recommendations. Nevertheless, an extensive literature review using the PubMed database was conducted. The following terms, namely pediatric, childhood, cancer, pediatric oncology, malnutrition, undernutrition, refeeding syndrome, nutritional support, and nutrition, were used. The consensus was reached through the Delphi method. Comprehensive recommendations aim to identify malnutrition early in children with cancer and optimize nutritional interventions in this group. The statement underscores the importance of baseline and ongoing assessments of nutritional status and the identification of the risk factors for malnutrition development, and it presents tools that can be used to achieve these goals. This consensus statement establishes a standardized approach to nutritional support, aiming to optimize outcomes in pediatric cancer patients.

Optimal Dietary Intake of Riboflavin Associated with Lower Risk of Cervical Cancer in Korea: Korean National Health and Nutrition Examination Survey 2010-2021

BACKGROUND

This study aimed to evaluate the association between the dietary intake of vitamin B complex (thiamine, riboflavin, and niacin) and cervical cancer in Korea.

METHODS

The data from the Korean National Health and Nutrition Examination Survey (KNHANES) from 2010 to 2021 were analyzed, which included 28,306 participants who were categorized into non-cervical cancer and cervical cancer groups. The following dietary intake threshold levels of thiamine, riboflavin, and niacin were identified based on the recommended daily allowances (RDAs): thiamine, 1.1 mg/day; riboflavin, 1.2 mg/day; and niacin, 14 mg/day.

RESULTS

Among 28,306 participants, 27,976 were in the non-cervical cancer group and 330 were in the cervical cancer group. Riboflavin intakes of more than 1.2 mg/day but less than 2.4 mg/day were associated with a significantly reduced risk of cervical cancer, whereas intakes of above 2.4 mg/day were not associated with cervical cancer. Thiamine and niacin intakes were not significantly related to the risk of cervical cancer.

CONCLUSIONS

The results of this study suggest that an intake of riboflavin of 1.2-2.4 mg/day may contribute to a lower risk of cervical cancer.

Supplement Use and Increased Risks of Cancer: Unveiling the Other Side of the Coin

There is a rising trend in the consumption of dietary supplements, especially among adults, with the purpose of improving health. While marketing campaigns tout the potential health benefits of using dietary supplements, it is critical to evaluate the potential harmful effects associated with these supplements as well. The majority of the scarce research on the potential harmful effects of vitamins focuses on the acute or chronic toxicities associated with the use of dietary supplements. Quality research is still required to further investigate the risks of long-term use of dietary supplements, especially the risk of developing cancers. The present review concentrates on studies that have investigated the association between the risk of developing cancers and associated mortality with the risk of dietary supplements. Such an association has been reported for several vitamins, minerals, and other dietary supplements. Even though several of these studies come with their own shortcomings and critics, they must draw attention to further investigate long-term adverse effects of dietary supplements and advise consumers and healthcare providers to ponder the extensive use of dietary supplements.

Game-theoretical description of the go-or-grow dichotomy in tumor development for various settings and parameter constellations

A medically important feature of several types of tumors is their ability to "decide" between staying at a primary site in the body or leaving it and forming metastases. The present theoretical study aims to provide a better understanding of the ultimate reasons for this so-called "go-or-grow" dichotomy. To that end, we use game theory, which has proven to be useful in analyzing the competition between tumors and healthy tissues or among different tumor cells. We begin by determining the game types in the Basanta-Hatzikirou-Deutsch model, depending on the parameter values. Thereafter, we suggest and analyze five modified variants of the model. For example, in the basic model, the deadlock game, Prisoner's Dilemma, and hawk-dove game can occur. The modified versions lead to several additional game types, such as battle of the sexes, route-choice, and stag-hunt games. For some game types, all cells are predicted to stay on their original site ("grow phenotype"), while for other types, only a certain fraction stay and the other cells migrate away ("go phenotype"). If the nutrient supply at a distant site is high, all the cells are predicted to go. We discuss our predictions in terms of the pros and cons of caloric restriction and limitations of the supply of vitamins or methionine. Our results may help devise treatments to prevent metastasis.

Metabolic control analysis as a strategy to identify therapeutic targets, the case of cancer glycolysis

The use of kinetic modeling and metabolic control analysis (MCA) to identify possible therapeutic targets and to investigate the controlling and regulatory mechanisms in cancer glycolysis is here reviewed. The glycolytic pathway has been considered a target to decrease cancer cell growth; however, its occurrence in normal cells makes it difficult to design therapeutic strategies that target this pathway in pathological cells. Notwithstanding, the over-expression of all enzymes and transporters, as well as the expression of isoenzymes with different kinetic and regulatory properties in cancer cells, suggested a different distribution of the control of glycolytic flux than that observed in normal cells. Kinetic models of glycolysis are constructed with enzyme kinetics experimental data, validated with the steady-state metabolite concentrations and glycolytic fluxes; applying MCA, permitted us to identify the steps with the highest control of glycolysis in cancer cells, but low control in normal cells. The cancer glycolysis main controlling steps under several metabolic conditions were: glucose transport, hexokinase and hexose-6-phosphate isomerase (HPI); whereas in normal cells were: the first two and phosphofructokinase-1. HPI is the best therapeutic target because it exerts high control in cancer glycolytic flux, but not in normal cells. Furthermore, kinetic modeling also contributed to identifying new feed-back and feed-forward regulatory loops in cancer cells glycolysis, and to understanding the mode of metabolic action of glycolytic inhibitors. Thus, MCA and metabolic modeling allowed to propose new strategies for inhibiting glycolysis in cancer cells.

Dietary B vitamins and glioma: A case-control study based on Chinese population

Background

Dietary antioxidants have long been thought to be likely to prevent the development of gliomas. Previous studies have reported vitamin A, C, and E protective effects against gliomas. B vitamins, one of the main vitamins in the diet, are closely related to human health, but the association with gliomas has rarely been reported.

Objective

This study aimed to evaluate the relationship between five B vitamins and glioma.

Methods

In this Chinese population-based case-control study, 506 glioma cases and 506 matched (age and sex) controls were included. The dietary intake of study participants was assessed using a valid 111-item food frequency questionnaire. The intake of five B vitamins was calculated based on participants' dietary information from the food frequency questionnaire. The logistic regression model was used to examine the association between B vitamins and glioma, and the restriction cubic spline evaluated the dose-response relationship between the two.

Results

After adjusting for confounding factors, thiamine (OR = 0.09, 95%CI: 0.05-0.20), riboflavin (OR = 0.12, 95%CI: 0.06-0.25), nicotinic acid (OR = 0.24, 95%CI: 0.12-0.47), folate (OR = 0.07, 95%CI: 0.03-0.15) and biotin (OR = 0.14, 95%CI: 0.07-0.30) in the highest tertile were associated with a significantly decreased risk of glioma compared with the lowest tertile. The results of thiamine and biotin in glioma with different pathological types and grades were different. The restricted cubic spline function showed significant dose-response relationships between the intake of five B vitamins and the risk of glioma. When B vitamins exceeded a specific intake, the risk of glioma did not change.

Conclusion

Our study suggests that higher dietary intake of thiamine, riboflavin, nicotinic acid, and folate are associated with a decreased risk of glioma, but the results of biotin are not consistent among different populations. In the future, prospective studies should be conducted better to validate the effects of B vitamins on gliomas.

Metabolomics Analysis Revealed Significant Metabolic Changes in Brain Cancer Cells Treated with Paclitaxel and/or Etoposide

Cancer of the central nervous system (CNS) is ranked as the 19th most prevalent form of the disease in 2020. This study aims to identify candidate biomarkers and metabolic pathways affected by paclitaxel and etoposide, which serve as potential treatments for glioblastoma, and are linked to the pathogenesis of glioblastoma. We utilized an untargeted metabolomics approach using the highly sensitive ultra-high-performance liquid chromatography-electrospray ionization quadrupole time-of-flight mass spectrometry (UHPLC-ESI-QTOF-MS) for identification. In this study, 92 and 94 metabolites in U87 and U373 cell lines were profiled, respectively. The produced metabolites were then analyzed utilizing t-tests, volcano plots, and enrichment analysis modules. Our analysis revealed distinct metabolites to be significantly dysregulated (nutriacholic acid, L-phenylalanine, L-arginine, guanosine, ADP, hypoxanthine, and guanine), and to a lesser extent, mevalonic acid in paclitaxel and/or etoposide treated cells. Furthermore, both urea and citric acid cycles, and metabolism of polyamines and amino acids (aspartate, arginine, and proline) were significantly enriched. These findings can be used to create a map that can be utilized to assess the antitumor effect of paclitaxel and/or etoposide within the studied cancer cells.

U-Shaped Relation of Dietary Thiamine Intake and New-Onset Hypertension

Background: To examine the relation of dietary thiamine intake with risk of new-onset hypertension in the general adults. Methods: A total of 12,177 participants without hypertension at baseline from China Health and Nutrition Survey (CHNS) were included. The study outcome was new-onset hypertension, which was defined as a systolic blood pressure ≥140 mm Hg or a diastolic blood pressure ≥90 mm Hg or under antihypertensive treatment or diagnosed by physician during the follow-up. Results: A total of 4269 participants occurred new-onset hypertension over a median follow-up of 6.1 years. Overall, there was a U-shaped relation (p for nonlinearity <0.001) of dietary thiamine intake with new-onset hypertension, with an inflection point at 0.93 mg/day. Accordingly, in the threshold effect analysis, there was an inverse association between dietary thiamine intake (per SD increment: HR, 0.62; 95% CI: 0.53, 0.72) and new-onset hypertension in participants with dietary thiamine intake <0.93 mg/day, and a positive association between dietary thiamine intake (per SD increment: HR, 1.38; 95% CI: 1.32, 1.44) and new-onset hypertension in those with dietary thiamine intake ≥0.93 mg/day. Conclusion: The association between dietary thiamine intake and the risk of new-onset hypertension followed a U-shaped relation in the general Chinese population, with an inflection point at 0.93 mg/day of dietary thiamine intake.

Exploring the Role of Metabolites in Cancer and the Associated Nerve Crosstalk

Since Otto Warburg's first report on the increased uptake of glucose and lactate release by cancer cells, dysregulated metabolism has been acknowledged as a hallmark of cancer that promotes proliferation and metastasis. Over the last century, studies have shown that cancer metabolism is complex, and by-products of glucose and glutamine catabolism induce a cascade of both pro- and antitumorigenic processes. Some vitamins, which have traditionally been praised for preventing and inhibiting the proliferation of cancer cells, have also been proven to cause cancer progression in a dose-dependent manner. Importantly, recent findings have shown that the nervous system is a key player in tumor growth and metastasis via perineural invasion and tumor innervation. However, the link between cancer-nerve crosstalk and tumor metabolism remains unclear. Here, we discuss the roles of relatively underappreciated metabolites in cancer-nerve crosstalk, including lactate, vitamins, and amino acids, and propose the investigation of nutrients in cancer-nerve crosstalk based on their tumorigenicity and neuroregulatory capabilities. Continued research into the metabolic regulation of cancer-nerve crosstalk will provide a more comprehensive understanding of tumor mechanisms and may lead to the identification of potential targets for future cancer therapies.

TKTL1 Knockdown Impairs Hypoxia-Induced Glucose-6-phosphate Dehydrogenase and Glyceraldehyde-3-phosphate Dehydrogenase Overexpression

Increased expression of transketolase (TKT) and its isoform transketolase-like-1 (TKTL1) has been related to the malignant leukemia phenotype through promoting an increase in the non-oxidative branch of the pentose phosphate pathway (PPP). Recently, it has also been described that TKTL1 can have a role in survival under hypoxic conditions and in the acquisition of radio resistance. However, TKTL1’s role in triggering metabolic reprogramming under hypoxia in leukemia cells has never been characterized. Using THP-1 AML cells, and by combining metabolomics and transcriptomics techniques, we characterized the impact of TKTL1 knockdown on the metabolic reprogramming triggered by hypoxia. Results demonstrated that TKTL1 knockdown results in a decrease in TKT, glucose-6-phosphate dehydrogenase (G6PD) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activities and impairs the hypoxia-induced overexpression of G6PD and GAPDH, all having significant impacts on the redox capacity of NADPH- and NADH-related cells. Moreover, TKTL1 knockdown impedes hypoxia-induced transcription of genes encoding key enzymes and transporters involved in glucose, PPP and amino acid metabolism, rendering cells unable to switch to enhanced glycolysis under hypoxia. Altogether, our results show that TKTL1 plays a key role in the metabolic adaptation to hypoxia in THP-1 AML cells through modulation of G6PD and GAPDH activities, both regulating glucose/glutamine consumption and the transcriptomic overexpression of key players of PPP, glucose and amino acids metabolism.

The Pentose Phosphate Pathway in Cancer: Regulation and Therapeutic Opportunities

BACKGROUND

Tumorigenesis is associated with deregulation of nutritional requirements, intermediary metabolites production, and microenvironment interactions. Unlike their normal cell counterparts, tumor cells rely on aerobic glycolysis, through the Warburg effect.

SUMMARY

The pentose phosphate pathway (PPP) is a major glucose metabolic shunt that is upregulated in cancer cells. The PPP comprises an oxidative and a nonoxidative phase and is essential for nucleotide synthesis of rapidly dividing cells. The PPP also generates nicotinamide adenine dinucleotide phosphate, which is required for reductive metabolism and to counteract oxidative stress in tumor cells. This article reviews the regulation of the PPP and discusses inhibitors that target its main pathways. Key Message: Exploiting the metabolic vulnerability of the PPP offers potential novel therapeutic opportunities and improves patients' response to cancer therapy.

Thiamine ameliorates metabolic disorders induced by a long-term high-concentrate diet and promotes rumen epithelial development in goats

Data indicate that dietary thiamine supplementation can partly alleviate rumen epithelium inflammation and barrier function in goats fed a high-concentrate diet. The current work aimed to explore whether thiamine promotes rumen epithelium development by regulating carbohydrate metabolism during a long period of feeding high levels of concentrate. For the experiment, 24 female Boer goats (35.62 ± 2.4 kg of body weight) in parity 1 or 2 were allocated to 3 groups (8 goats per replicate) receiving a low-concentrate diet (concentrate:forage 30:70), a high-concentrate diet (HC; concentrate:forage 70:30), or a high-concentrate diet (concentrate:forage 70:30) supplemented with 200 mg of thiamine/kg of dry matter intake (HCT; concentrate:forage 70:30). On the last day of 12 wk, rumen fluid and blood samples were collected to measure ruminal parameters, endotoxin lipopolysaccharide, and blood inflammatory cytokines. Goats were slaughtered to collect ruminal tissue to determine differential metabolites, enzyme activities, and gene expression. Liquid chromatography-tandem mass spectrometry analysis revealed that the HCT group had significantly increased concentrations of d-glucose 6-phosphate, d-fructose 6-phosphate, glyceraldehyde 3-phosphate, thiamine pyrophosphate, oxaloacetate, acetyl-CoA, succinyl-CoA, sedoheptulose 7-phosphate, ribose 5-phosphate, and NADPH compared with the HC group. The pyruvate dehydrogenase, α-ketoglutarate dehydrogenase, and transketolase enzyme activities in the rumen epithelium of the HCT group were higher than those in the HC group. The plasma total antioxidant capacity values for the HCT group were greater than those for the HC group. The rumen epithelium ATP content in the HCT group was higher than that in the HC group. Compared with the HCT group, the HC group had a lower mRNA abundance of CCND1, CCNA2, CDK2, CDK4, CDK6, BCL2, PI3K, and AKT1. Taken together, the results suggest that dietary thiamine supplementation could ameliorate disorders in the tricarboxylic acid cycle and the pentose phosphate pathway induced by a long-term high-concentrate diet and could promote rumen epithelial growth.

Effect of Breast Cancer Treatment on Dietary Vitamin Intake Levels

Breast cancer is the most common tumor among women, representing the second cause of cancer deaths in women. Treatment with chemotherapy negatively interferes with nutritional status. The intake of vitamins before, during and after treatment in a pilot cohort of women with non-invasive breast cancer (type I, II) treated at the Valencian Institute of Oncology (IVO) is evaluated. A 3-day anthropometric and nutritional assessment was performed using the DIAL program. Nutritional intake is compared with the values of Estimated Average Requirements (EAR) and Dietary Reference Intake (DRI) provided by the United States Department of Agriculture (USDA) and the European Food Safety Authority (EFSA). There is an overall decrease in vitamin intake during treatment which worsens at the end of said treatment. The decrease is significant in the case of vitamins B₂ (p = 0.006), B₃ (p = 0.042), B₅ (p = 0.001), and B₈ (p = 0.021). The relative risk during and after treatment increases with respect to the reference timeframe, before treatment. Deficit risks are statistically significant in the case of vitamins B₅ (p = 0.001), B₈ (p = 0.001) and B₁₂ (p = 0.001). Decreased vitamin intake during treatment suggests a negative change in the patients’ dietary behaviors during this time. Nutritional intervention and support may be beneficial to optimize overall dietary intake and maintain compliance with EAR and DRI for patients during a time in which adequate nutrition is important.

B Vitamins and Their Role in Immune Regulation and Cancer

B group vitamins represent essential micronutrients for myriad metabolic and regulatory processes required for human health, serving as cofactors used by hundreds of enzymes that carry out essential functions such as energy metabolism, DNA and protein synthesis and other critical functions. B vitamins and their corresponding vitamers are universally essential for all cellular life forms, from bacteria to humans. Humans are unable to synthesize most B vitamins and are therefore dependent on their diet for these essential micronutrients. More recently, another source of B vitamins has been identified which is derived from portions of the 10¹³ bacterial cells inhabiting the gastrointestinal tract. Here we review the expanding literature examining the relationship between B vitamins and the immune system and diverse cancers. Evidence of B vitamin’s role in immune cell regulation has accumulated in recent years and may help to clarify the disparate findings of numerous studies attempting to link B vitamins to cancer development. Much work remains to be carried out to fully clarify these relationships as the complexity of B vitamins’ essential functions complicates an unequivocal assessment of their beneficial or detrimental effects in inflammation and cancers.

Identification of Immune-Related Prognostic Genes and LncRNAs Biomarkers Associated With Osteosarcoma Microenvironment

Osteosarcoma (OS) is the most common malignancy of the bone that occurs majorly in young people and adolescents. Although the survival of OS patients markedly improved by complete surgical resection and chemotherapy, the outcome is still poor in patients with recurrent and/or metastasized OS. Thus, identifying prognostic biomarkers that reflect the biological heterogeneity of OS could lead to better interventions for OS patients. Increasing studies have indicated the association between immune-related genes (IRGs) and cancer prognosis. In the present study, based on the data concerning OS obtained from TARGET (Therapeutically Applicable Research to Generate Effective Treatments) database, we constructed a classifier containing 12 immune-related (IR) long non-coding RNAs (lncRNAs) and 3 IRGs for predicting the prognosis of OS by using the least absolute shrinkage and selection operation Cox regression. Besides, based on the risk score calculated by the classifier, the samples were divided into high- and low-risk groups. We further investigated the tumor microenvironment of the OS samples by ESTIMATE and CIBERSORT algorithms between the two groups. Finally, we identified three small molecular drugs with potential therapeutic value for OS patients with high-risk score. Our results suggest that the IRGs and IR-lncRNAs–based classifier could be used as a reliable prognostic predictor for OS survival.

Activation of Mitochondrial 2-Oxoglutarate Dehydrogenase by Cocarboxylase in Human Lung Adenocarcinoma Cells A549 Is p53/p21-Dependent and Impairs Cellular Redox State, Mimicking the Cisplatin Action

Genetic up-regulation of mitochondrial 2-oxoglutarate dehydrogenase is known to increase reactive oxygen species, being detrimental for cancer cells. Thiamine diphosphate (ThDP, cocarboxylase) is an essential activator of the enzyme and inhibits p53–DNA binding in cancer cells. We hypothesize that the pleiotropic regulator ThDP may be of importance for anticancer therapies. The hypothesis is tested in the present work on lung adenocarcinoma cells A549 possessing the p53–p21 pathway as fully functional or perturbed by p21 knockdown. Molecular mechanisms of ThDP action on cellular viability and their interplay with the cisplatin and p53–p21 pathways are characterized. Despite the well-known antioxidant properties of thiamine, A549 cells exhibit decreases in their reducing power and glutathione level after incubation with 5 mM ThDP, not observed in non-cancer epithelial cells Vero. Moreover, thiamine deficiency elevates glutathione in A549 cells. Viability of the thiamine deficient A549 cells is increased at a low (0.05 mM) ThDP. However, the increase is attenuated by 5 mM ThDP, p21 knockdown, specific inhibitor of the 2-oxoglutarate dehydrogenase complex (OGDHC), or cisplatin. Cellular levels of the catalytically competent ThDP·OGDHC holoenzyme are dysregulated by p21 knockdown and correlate negatively with the A549 viability. The inverse relationship between cellular glutathione and holo-OGDHC is corroborated by their comparison in the A549 and Vero cells. The similarity, non-additivity, and p21 dependence of the dual actions of ThDP and cisplatin on A549 cells manifest a common OGDHC-mediated mechanism of the viability decrease. High ThDP saturation of OGDHC compromises the redox state of A549 cells under the control of p53–p21 axes.

Role of the Synthetic B1 Vitamin Sulbutiamine on Health

Sulbutiamine is a thiamine derivative developed in Japan in the mid-60's as a beriberi treatment drug. Since then, different potential applications have been described. For instance, there is some evidence that sulbutiamine can have anti-fatigue, nootropic, and antioxidant effects, which led to its use as a sport supplement (although some authors argue it is actually a masking doping strategy). Moreover, this molecule has been proposed as a possible treatment for some microsporidial infections and even for certain types of cancer. Despite these potential effects, sulbutiamine is still a relatively unknown molecule, which justifies the present review, where we discuss its history and the existing literature on its health applications. We conclude that there is a great potential for sulbutiamine use, well beyond its first described function (to increase thiamine tissue concentration). Indeed, new mechanisms of action have been found, mainly associated with its derivatives. Nevertheless, and although the research on sulbutiamine started 50 years ago, only a limited number of studies were conducted during this time frame. As so, methodological concerns need to be addressed and new studies are necessary, especially randomized controlled trials. Only then will the full potential of this versatile molecule be identified.

The Two-Species Model of transketolase explains donor substrate-binding, inhibition and heat-activation

We recently characterised a low-activity form of E. coli transketolase, TK_low, which also binds the cofactor thiamine pyrophosphate (TPP) with an affinity up to two-orders of magnitude lower than the previously known high TPP-affinity and high-activity form, TK_high, in the presence of Mg²⁺. We observed previously that partial oxidation was responsible for increased TK_high activity, while low-activity TK_low was unmodified. In the present study, the fluorescence-based cofactor-binding assay was adapted to detect binding of the β-hydroxypyruvate (HPA) donor substrate to wild-type transketolase and a variant, S385Y/D469T/R520Q, that is active towards aromatic aldehydes. Transketolase HPA affinity again revealed the two distinct forms of transketolase at a TK_high:TK_low ratio that matched those observed previously via TPP binding to each variant. The HPA dissociation constant of TK_low was comparable to the substrate-inhibition dissociation constant, K_i^HPA, determined previously. We provide evidence that K_i^HPA is a convolution of binding to the low-activity TK_low-TK_low dimer, and the TK_low subunit of the partially-active TK_high-TK_low mixed dimer, where HPA binding to the TK_low subunit of the mixed dimer results in inhibition of the active TK_high subunit. Heat-activation of transketolase was similarly investigated and found to convert the TK_low subunit of the mixed dimer to have TK_high-like properties, but without oxidation.

Thiamine mimetics sulbutiamine and benfotiamine as a nutraceutical approach to anticancer therapy

Malignant cells frequently demonstrate an oncogenic-driven reliance on glycolytic metabolism to support their highly proliferative nature. Overexpression of pyruvate dehydrogenase kinase (PDK) may promote this unique metabolic signature of tumor cells by inhibiting mitochondrial function. PDKs function to phosphorylate and inhibit pyruvate dehydrogenase (PDH) activity. Silencing of PDK expression has previously been shown to restore mitochondrial function and reduce tumor cell proliferation. High dose Vitamin B1, or thiamine, possesses antitumor properties related to its capacity to reduce PDH phosphorylation and promote its enzymatic activity, presumably through PDK inhibition. Though a promising nutraceutical approach for cancer therapy, thiamine's low bioavailability may limit clinical effectiveness. Here, we have demonstrated exploiting the commercially available lipophilic thiamine analogs sulbutiamine and benfotiamine increases thiamine's anti-cancer effect in vitro. Determined by crystal violet proliferation assays, both sulbutiamine and benfotiamine reduced thiamine's millimolar IC50 value to micromolar equivalents. HPLC analysis revealed that sulbutiamine and benfotiamine significantly increased intracellular thiamine and TPP concentrations in vitro, corresponding with reduced levels of PDH phosphorylation. Through an ex vitro kinase screen, thiamine's activated cofactor form thiamine pyrophosphate (TPP) was found to inhibit the function of multiple PDK isoforms. Attempts to maximize intracellular TPP by exploiting thiamine homeostasis gene expression resulted in enhanced apoptosis in tumor cells. Based on our in vitro evaluations, we conclude that TPP serves as the active species mediating thiamine's inhibitory effect on tumor cell proliferation. Pharmacologic administration of benfotiamine, but not sulbutiamine, reduced tumor growth in a subcutaneous xenograft mouse model. It remains unclear if benfotiamine's effects in vivo are associated with PDK inhibition or through an alternative mechanism of action. Future work will aim to define the action of lipophilic thiamine mimetics in vivo in order to translate their clinical usefulness as anticancer strategies.

Humanized yeast genetic interaction mapping predicts synthetic lethal interactions of FBXW7 in breast cancer

Background

Synthetic lethal interactions (SLIs) that occur between gene pairs are exploited for cancer therapeutics. Studies in the model eukaryote yeast have identified ~ 550,000 negative genetic interactions that have been extensively studied, leading to characterization of novel pathways and gene functions. This resource can be used to predict SLIs that can be relevant to cancer therapeutics.

Methods

We used patient data to identify genes that are down-regulated in breast cancer. InParanoid orthology mapping was performed to identify yeast orthologs of the down-regulated genes and predict their corresponding SLIs in humans. The predicted network graphs were drawn with Cytoscape. CancerRXgene database was used to predict drug response.

Results

Harnessing the vast available knowledge of yeast genetics, we generated a Humanized Yeast Genetic Interaction Network (HYGIN) for 1009 human genes with 10,419 interactions. Through the addition of patient-data from The Cancer Genome Atlas (TCGA), we generated a breast cancer specific subnetwork. Specifically, by comparing 1009 genes in HYGIN to genes that were down-regulated in breast cancer, we identified 15 breast cancer genes with 130 potential SLIs. Interestingly, 32 of the 130 predicted SLIs occurred with FBXW7, a well-known tumor suppressor that functions as a substrate-recognition protein within a SKP/CUL1/F-Box ubiquitin ligase complex for proteasome degradation. Efforts to validate these SLIs using chemical genetic data predicted that patients with loss of FBXW7 may respond to treatment with drugs like Selumitinib or Cabozantinib.

Conclusions

This study provides a patient-data driven interpretation of yeast SLI data. HYGIN represents a novel strategy to uncover therapeutically relevant cancer drug targets and the yeast SLI data offers a major opportunity to mine these interactions.

Electronic supplementary material

The online version of this article (10.1186/s12920-019-0554-z) contains supplementary material, which is available to authorized users.

Development of an IPRP-LC-MS/MS method to determine the fate of intracellular thiamine in cancer cells

Understanding the mechanisms underlying cancer cell survival is critical toward advancing drug discovery efforts in this field. Supplemental vitamins have been proposed to play a role in cancer cell metabolism because the increased supply of nutrients is thought to provide cofactors supporting the higher metabolic rate of cancer cells. Particularly, the role of thiamine (vitamin B1) in many biochemical pathways that supports cancer cell metabolism has been investigated. Consequently, the analysis of thiamine and its derivatives in a manner that reflects its dynamic response to genetic modification and pathophysiological stimuli is essential. In this work, we developed a mass spectrometry based-analytical method to track metabolites derived from stable isotope tracers for a better understanding of the metabolic fate of thiamine in cancer cells. This method used ion-pair reversed phase liquid chromatography to simultaneously quantify underivatized thiamine, thiamine monophosphate (TMP) and thiamine pyrophosphate (TPP) in cells. Hexylamine was used as an ion-pairing agent. The method was successfully validated for accuracy, precision and selectivity in accordance with U.S. FDA guidance. Furthermore, the method was then applied for the determination of thiamine and its derivatives with stable isotope labeling to explore the metabolic fate of intracellular thiamine in cancer cells. The finding shows that thiamine is rapidly converted to TPP however, the TPP does not return to thiamine. It appears that TPP may be utilized for other purposes rather than simply being an enzyme cofactor, suggesting unexplored roles for thiamine in cancer.

The adaptive regulation of thiamine pyrophosphokinase-1 facilitates malignant growth during supplemental thiamine conditions

Supplemental levels of vitamin B1 (thiamine) have been implicated in tumor progression. Tumor cells adaptively up-regulate thiamine transport during hypoxic stress. Upon uptake, thiamine pyrophosphokinase-1 (TPK1) facilitates the rapid phosphorylation of thiamine into thiamine pyrophosphate (TPP). However, the regulation of TPK1 during hypoxic stress is undefined. Understanding how thiamine homeostasis changes during hypoxia will provide critical insight into the malignant advantage supplemental thiamine may provide cancer cells. Using Western blot analysis and RT-PCR, we have demonstrated the post-transcriptional up-regulation of TPK1 in cancer cells following hypoxic exposure. TPK1 expression was also adaptively up-regulated following alterations of redox status by chemotherapeutic and antioxidant treatments. Although TPK1 was functionally up-regulated by hypoxia, HPLC analysis revealed a reduction in intracellular TPP levels. This loss was reversed by treatment with cell-permeable antioxidants and corresponded with reduced ROS production and enhanced cellular proliferation during supplemental thiamine conditions. siRNA-mediated knockdown of TPK1 directly enhanced basal ROS levels and reduced tumor cell proliferation. These findings suggest that the adaptive regulation of TPK1 may be an essential component in the cellular response to oxidative stress, and that during supplemental thiamine conditions its expression may be exploited by tumor cells for a redox advantage contributing to tumor progression.

Can folate replacement induce lymphoma progression?

A 43-year-old Japanese man with a low haemoglobin level of 1.3 g/dL and multiorgan dysfunction syndrome (MODS) was admitted to our hospital. He was diagnosed with folate deficiency, which was initially attributed to his malnutrition. He was transfused with several units of packed red blood cells and treated with folate, thiamine and vitamin B₁₂ supplements; he showed a prompt haematological response and recovery from MODS. However, 3 weeks after the initial recovery, he had a relapse of pancytopenia and developed high-grade fever along with rapidly enlarging, generalised lymphadenopathy. Bone marrow biopsy revealed hemophagocytosis, and lymph node biopsy revealed peripheral T-cell lymphoma, not otherwise specified. Folate supplementation may have promoted lymphoma progression.

The Effects of Thiamine on Breast Cancer Cells

(1) Background: Thiamine is an important cofactor for multiple metabolic processes. Its role in cancer has been debated for years. Our aim is to determine if thiamine can convert the cellular metabolic state of breast cancer cells from anaerobic to aerobic, thus reducing their growth. (2) Methods: Breast cancer (MCF7) and non-tumorigenic (MCF10A) cell lines were treated with various doses of thiamine and assessed for changes in cell growth. The mechanism of this relationship was identified through the measurement of enzymatic activity and metabolic changes. (3) Results: A high dose of thiamine reduced cell proliferation in MCF7 (63% decrease, p < 0.0001), but didn’t affect apoptosis and the cell-cycle profile. Thiamine had a number of effects in MCF7; it (1) reduced extracellular lactate levels in growth media, (2) increased cellular pyruvate dehydrogenase (PDH) activities and the baseline and maximum cellular oxygen consumption rates, and (3) decreased non-glycolytic acidification, glycolysis, and glycolytic capacity. MCF10A cells preferred mitochondrial respiration instead of glycolysis. In contrast, MCF7 cells were more resistant to mitochondrial respiration, which may explain the inhibitory effect of thiamine on their proliferation. (4) Conclusions: The treatment of MCF7 breast cancer cells with 1 μg/mL and 2 μg/mL of thiamine for 24 h significantly reduced their proliferation. This reduction is associated with a reduction in glycolysis and activation of the PDH complex in breast cancer cells.

TP53 mutation hits energy metabolism and increases glycolysis in breast cancer

Promising new hallmarks of cancer is alteration of energy metabolism that involves molecular mechanisms shifting cancer cells to aerobe glycolysis. Our goal was to evaluate the correlation between mutation in the commonly mutated tumor suppressor gene TP53 and metabolism. We established a database comprising mutation and RNA-seq expression data of the TCGA repository and performed receiver operating characteristics (ROC) analysis to compare expression of each gene between TP53 mutated and wild type samples. All together 762 breast cancer samples were evaluated of which 215 had TP53 mutation. Top up-regulated metabolic genes include glycolytic enzymes (e.g. HK3, GPI, GAPDH, PGK1, ENO1), glycolysis regulator (PDK1) and pentose phosphate pathway enzymes (PGD, TKT, RPIA). Gluconeogenesis enzymes (G6PC3, FBP1) were down-regulated. Oxygen consumption and extracellular acidification rates were measured in TP53 wild type and mutant breast cell lines with a microfluorimetric analyzer. Applying metabolic inhibitors in the presence and absence of D-glucose and L-glutamine in cell culture experiments resulted in higher glycolytic and mitochondrial activity in TP53 mutant breast cancer cell lines. In summary, TP53 mutation influences energy metabolism at multiple levels. Our results provide evidence for the synergistic activation of multiple hallmarks linking to these the mutation status of a key driver gene.

The effect of "NutramilTM Complex," food for special medical purpose, on breast and prostate carcinoma cells

NutramilTM Complex is a multicomponent food product that meets the requirements of a food for special medical purpose. As a complete, high-energy diet it consists of properly balanced nutrients, vitamins and minerals. The aim of this study was to assess the effect of NutramilTM Complex on breast and prostate carcinoma cells. Our results showed that NutramilTM Complex reduced the viability and proliferation of breast and prostate cancer cells and that this process was associated with the induction of apoptosis via activation of caspase signalling. Data showed elevated levels of p53 tumour suppressor, up-regulation of p38 MAPK and SAPK / JNK proteins and downregulation of anti-apoptotic ERK1/2, AKT1 and HSP27. Treatment with NutramilTM Complex also affected the expression of the BCL2 family genes. Results also showed down-regulation of anti-apoptotic BCL-2 and up-regulation of pro-apoptotic members such as BAX, BAD, BID. In addition, we also observed regulation of many other genes, including Iκβα, Chk1 and Chk2, associated with apoptotic events. Taken together, our results suggest activation of the mitochondrial apoptotic pathway as most likely mechanism of anti-carcinogenic activity of NutramilTM Complex.

Inhibition of mitochondrial 2-oxoglutarate dehydrogenase impairs viability of cancer cells in a cell-specific metabolism-dependent manner

2-Oxoglutarate dehydrogenase (OGDH) of the tricarboxylic acid (TCA) cycle is often implied to be inactive in cancer, but this was not experimentally tested. We addressed the question through specific inhibition of OGDH by succinyl phosphonate (SP). SP action on different cancer cells was investigated using indicators of cellular viability and reactive oxygen species (ROS), metabolic profiling and transcriptomics. Relative sensitivity of various cancer cells to SP changed with increasing SP exposure and could differ in the ATP- and NAD(P)H-based assays. Glioblastoma responses to SP revealed metabolic sub-types increasing or decreasing cellular ATP/NAD(P)H ratio under OGDH inhibition. Cancer cell homeostasis was perturbed also when viability indicators were SP-resistant, e.g. in U87 and N2A cells. The transcriptomics database analysis showed that the SP-sensitive cells, such as A549 and T98G, exhibit the lowest expression of OGDH compared to other TCA cycle enzymes, associated with higher expression of affiliated pathways utilizing 2-oxoglutarate. Metabolic profiling confirmed the dependence of cellular SP reactivity on cell-specific expression of the pathways. Thus, oxidative decarboxylation of 2-oxoglutarate is significant for the interdependent homeostasis of NAD(P)H, ATP, ROS and key metabolites in various cancer cells. Assessment of cell-specific responses to OGDH inhibition is of diagnostic value for anticancer strategies.

Glucose-6-phosphate dehydrogenase and transketolase modulate breast cancer cell metabolic reprogramming and correlate with poor patient outcome

The pentose phosphate pathway is a fundamental metabolic pathway that provides cells with ribose and NADPH required for anabolic reactions — synthesis of nucleotides and fatty acids — and maintenance of intracellular redox homeostasis. It plays a key role in tumor metabolic reprogramming and has been reported to be deregulated in different types of tumors. Herein, we silenced the most important enzymes of this pathway — glucose-6-phosphate dehydrogenase (G6PD) and transketolase (TKT) — in the human breast cancer cell line MCF7. We demonstrated that inhibition of G6PD, the oxidative branch-controlling enzyme, reduced proliferation, cell survival and increased oxidative stress. At the metabolic level, silencing of both enzymes reduced ribose synthesis. G6PD silencing in particular, augmented the glycolytic flux, reduced lipid synthesis and increased glutamine uptake, whereas silencing of TKT reduced the glycolytic flux. Importantly, we showed using breast cancer patient datasets that expression of both enzymes is positively correlated and that high expression levels of G6PD and TKT are associated with decreased overall and relapse-free survival. Altogether, our results suggest that this metabolic pathway could be subjected to therapeutic intervention to treat breast tumors and warrant further investigation.

Reconstruction of Tissue-Specific Metabolic Networks Using CORDA

Human metabolism involves thousands of reactions and metabolites. To interpret this complexity, computational modeling becomes an essential experimental tool. One of the most popular techniques to study human metabolism as a whole is genome scale modeling. A key challenge to applying genome scale modeling is identifying critical metabolic reactions across diverse human tissues. Here we introduce a novel algorithm called Cost Optimization Reaction Dependency Assessment (CORDA) to build genome scale models in a tissue-specific manner. CORDA performs more efficiently computationally, shows better agreement to experimental data, and displays better model functionality and capacity when compared to previous algorithms. CORDA also returns reaction associations that can greatly assist in any manual curation to be performed following the automated reconstruction process. Using CORDA, we developed a library of 76 healthy and 20 cancer tissue-specific reconstructions. These reconstructions identified which metabolic pathways are shared across diverse human tissues. Moreover, we identified changes in reactions and pathways that are differentially included and present different capacity profiles in cancer compared to healthy tissues, including up-regulation of folate metabolism, the down-regulation of thiamine metabolism, and tight regulation of oxidative phosphorylation.

The Warburg effect: a balance of flux analysis

Cancer metabolism is characterized by increased macromolecular syntheses through coordinated increases in energy and substrate metabolism. The observation that cancer cells produce lactate in an environment of oxygen sufficiency (aerobic glycolysis) is a central theme of cancer metabolism known as the Warburg effect. Aerobic glycolysis in cancer metabolism is accompanied by increased pentose cycle and anaplerotic activities producing energy and substrates for macromolecular synthesis. How these processes are coordinated is poorly understood. Recent advances have focused on molecular regulation of cancer metabolism by oncogenes and tumor suppressor genes which regulate numerous enzymatic steps of central glucose metabolism. In the past decade, new insights in cancer metabolism have emerged through the application of stable isotopes particularly from ¹³C carbon tracing. Such studies have provided new evidence for system-wide changes in cancer metabolism in response to chemotherapy. Interestingly, experiments using metabolic inhibitors on individual biochemical pathways all demonstrate similar system-wide effects on cancer metabolism as in targeted therapies. Since biochemical reactions in the Warburg effect place competing demands on available precursors, high energy phosphates and reducing equivalents, the cancer metabolic system must fulfill the condition of balance of flux (homeostasis). In this review, the functions of the pentose cycle and of the tricarboxylic acid (TCA) cycle in cancer metabolism are analyzed from the balance of flux point of view. Anticancer treatments that target molecular signaling pathways or inhibit metabolism alter the invasive or proliferative behavior of the cancer cells by their effects on the balance of flux (homeostasis) of the cancer metabolic phenotype.

Transketolase is upregulated in metastatic peritoneal implants and promotes ovarian cancer cell proliferation

Ovarian cancer, the most lethal gynaecological cancer, is characterised by the shedding of epithelial cells from the ovarian surface, followed by metastasis and implantation onto the peritoneal surfaces of abdominal organs. Our proteomic studies investigating the interactions between peritoneal (LP-9) and ovarian cancer (OVCAR-5) cells found transketolase (TKT) to be regulated in the co-culture system. This study characterized TKT expression in advanced stage (III/IV) serous ovarian cancers (n = 125 primary and n = 54 peritoneal metastases), normal ovaries (n = 6) and benign serous cystadenomas (n = 10) by immunohistochemistry. In addition, we also evaluated the function of TKT in ovarian cancer cells in vitro. Nuclear TKT was present in all primary serous ovarian cancer tissues examined (median 82.0 %, range 16.5-100 %) and was significantly increased in peritoneal metastases compared with matching primary cancers (P = 0.01, Wilcoxon Rank test). Kaplan-Meier survival and Cox regression analyses showed that high nuclear TKT positivity in peritoneal metastases (>94 %) was significantly associated with reduced overall survival (P = 0.006) and a 2.8 fold increased risk of ovarian cancer death (95 % CI 1.29-5.90, P = 0.009). Knockdown of TKT by siRNAs significantly reduced SKOV-3 cell proliferation but had no effect on their motility or invasion. Oxythiamine, an inhibitor of TKT activity, significantly inhibited the proliferation of four ovarian cancer cell lines (OV-90, SKOV-3, OVCAR-3 and OVCAR-5) and primary serous ovarian cancer cells isolated from patient ascites. In conclusion, these findings indicate that TKT plays an important role in the proliferation of metastatic ovarian cancer cells and could be used as novel therapeutic target for advanced disease.

Analysis and interpretation of transcriptomic data obtained from extended Warburg effect genes in patients with clear cell renal cell carcinoma

Background

Many cancers adopt a metabolism that is characterized by the well-known Warburg effect (aerobic glycolysis). Recently, numerous attempts have been made to treat cancer by targeting one or more gene products involved in this pathway without notable success. This work outlines a transcriptomic approach to identify genes that are highly perturbed in clear cell renal cell carcinoma (CCRCC).

Methods

We developed a model of the extended Warburg effect and outlined the model using Cytoscape. Following this, gene expression fold changes (FCs) for tumor and adjacent normal tissue from patients with CCRCC (GSE6344) were mapped on to the network. Gene expression values with FCs of greater than two were considered as potential targets for treatment of CCRCC.

Results

The Cytoscape network includes glycolysis, gluconeogenesis, the pentose phosphate pathway (PPP), the TCA cycle, the serine/glycine pathway, and partial glutaminolysis and fatty acid synthesis pathways. Gene expression FCs for nine of the 10 CCRCC patients in the GSE6344 data set were consistent with a shift to aerobic glycolysis. Genes involved in glycolysis and the synthesis and transport of lactate were over-expressed, as was the gene that codes for the kinase that inhibits the conversion of pyruvate to acetyl-CoA. Interestingly, genes that code for unique proteins involved in gluconeogenesis were strongly under-expressed as was also the case for the serine/glycine pathway. These latter two results suggest that the role attributed to the M2 isoform of pyruvate kinase (PKM2), frequently the principal isoform of PK present in cancer: i.e. causing a buildup of glucose metabolites that are shunted into branch pathways for synthesis of key biomolecules, may not be operative in CCRCC. The fact that there was no increase in the expression FC of any gene in the PPP is consistent with this hypothesis. Literature protein data generally support the transcriptomic findings.

Conclusions

A number of key genes have been identified that could serve as valid targets for anti-cancer pharmaceutical agents. Genes that are highly over-expressed include ENO2, HK2, PFKP, SLC2A3, PDK1, and SLC16A1. Genes that are highly under-expressed include ALDOB, PKLR, PFKFB2, G6PC, PCK1, FBP1, PC, and SUCLG1.

Type B lactic acidosis secondary to thiamine deficiency in a child with malignancy

Type B lactic acidosis is an underrecognized clinical entity that must be distinguished from type A (hypoxic) lactic acidosis. We present the case of a 4-year-old boy with medulloblastoma who presented with lactic acidosis in the setting of septic shock. His hyperlactatemia persisted to high levels even after his hemodynamic status improved. After administration of intravenous thiamine, his lactate level rapidly normalized and remained stable. It was determined that his total parenteral nutrition was deficient in vitamins due to a national shortage. Because thiamine is an important cofactor for pyruvate dehydrogenase, he was unable to use glucose through aerobic metabolism pathways. We briefly review type A versus type B lactic acidosis in this case report.

Evidence for a transketolase-mediated metabolic checkpoint governing biotrophic growth in rice cells by the blast fungus Magnaporthe oryzae

The blast fungus Magnaporthe oryzae threatens global food security through the widespread destruction of cultivated rice. Foliar infection requires a specialized cell called an appressorium that generates turgor to force a thin penetration hypha through the rice cuticle and into the underlying epidermal cells, where the fungus grows for the first days of infection as a symptomless biotroph. Understanding what controls biotrophic growth could open new avenues for developing sustainable blast intervention programs. Here, using molecular genetics and live-cell imaging, we dismantled M. oryzae glucose-metabolizing pathways to reveal that the transketolase enzyme, encoded by TKL1, plays an essential role in facilitating host colonization during rice blast disease. In the absence of transketolase, Δtkl1 mutant strains formed functional appressoria that penetrated rice cuticles successfully and developed invasive hyphae (IH) in rice cells from primary hyphae. However, Δtkl1 could not undertake sustained biotrophic growth or cell-to-cell movement. Transcript data and observations using fluorescently labeled histone H1:RFP fusion proteins indicated Δtkl1 mutant strains were alive in host cells but were delayed in mitosis. Mitotic delay could be reversed and IH growth restored by the addition of exogenous ATP, a metabolite depleted in Δtkl1 mutant strains. We show that ATP might act via the TOR signaling pathway, and TOR is likely a downstream target of activation for TKL1. TKL1 is also involved in controlling the migration of appressorial nuclei into primary hyphae in host cells. When taken together, our results indicate transketolase has a novel role in mediating - via ATP and TOR signaling - an in planta-specific metabolic checkpoint that controls nuclear migration from appressoria into primary hyphae, prevents mitotic delay in early IH and promotes biotrophic growth. This work thus provides new information about the metabolic strategies employed by M. oryzae to enable rice cell colonization.

The blast fungus Magnaporthe oryzae destroys rice and wheat harvests and could compromise global food security. Following penetration into the rice cell, M. oryzae elaborates bulbous invasive hyphae that grow in living rice cells for most of the infection cycle without causing disease symptoms. Little is known about the physiological processes governing this important biotrophic stage of fungal growth. Here, we used gene functional analysis to show how the primary metabolic enzyme transketolase is essential for hyphal growth in rice cells. Loss of transketolase did not affect the ability of the fungus to gain entry into rice cells, but invasive hyphal growth was curtailed in transketolase null mutants. Biotrophic growth was restored in transketolase mutants by the addition of exogenous ATP. We conclude that M. oryzae metabolism is dedicated to metabolizing glucose through transketolase in planta in order to provide ATP as a trigger for biotrophic growth and infection. This work is significant because it reveals important—but previously unknown—metabolic strategies employed by M. oryzae to facilitate rice infection. These strategies might be open to abrogation by chemical or biological means and are likely relevant to other rapidly proliferating intracellular pathogens.

Akt phosphorylation and regulation of transketolase is a nodal point for amino acid control of purine synthesis

The phosphatidylinositol 3-kinase (PI3K)/Akt pathway integrates environmental clues to regulate cell growth and survival. We showed previously that depriving cells of a single essential amino acid rapidly and reversibly arrests purine synthesis. Here we demonstrate that amino acids via mammalian target of rapamycin 2 and IκB kinase regulate Akt activity and Akt association and phosphorylation of transketolase (TKT), a key enzyme of the nonoxidative pentose phosphate pathway (PPP). Akt phosphorylates TKT on Thr382, markedly enhancing enzyme activity and increasing carbon flow through the nonoxidative PPP, thereby increasing purine synthesis. Mice fed a lysine-deficient diet for 2 days show decreased Akt activity, TKT activity, and purine synthesis in multiple organs. These results provide a mechanism whereby Akt coordinates amino acid availability with glucose utilization, purine synthesis, and RNA and DNA synthesis.

High-dose vitamin B1 reduces proliferation in cancer cell lines analogous to dichloroacetate

PURPOSE

The dichotomous effect of thiamine supplementation on cancer cell growth is characterized by growth stimulation at low doses and growth suppression at high doses. Unfortunately, how thiamine reduces cancer cell proliferation is currently unknown. Recent focuses on metabolic targets for cancer therapy have exploited the altered regulation of the thiamine-dependent enzyme pyruvate dehydrogenase (PDH). Cancer cells inactivate PDH through phosphorylation by overexpression of pyruvate dehydrogenase kinases (PDKs). Inhibition of PDKs by dichloracetate (DCA) exhibits a growth suppressive effect in many cancers. Recently, it has been shown that the thiamine coenzyme, thiamine pyrophosphate reduces PDK-mediated phosphorylation of PDH. Therefore, the objective of this study was to determine whether high-dose thiamine supplementation reduces cell proliferation through a DCA-like mechanism.

METHODS

Cytotoxicity of thiamine and DCA was assessed in SK-N-BE and Panc-1 cancer cell lines. Comparative effects of high-dose thiamine and DCA on PDH phosphorylation were measured by Western blot. The metabolic impact of PDH reactivation was determined by glucose and lactate assays. Changes in the mitochondrial membrane potential, reactive oxygen species (ROS) production, and caspase-3 activation were assessed to characterize the mechanism of action.

RESULTS

Thiamine exhibited a lower IC50 value in both cell lines compared with DCA. Both thiamine and DCA reduced the extent of PDH phosphorylation, reduced glucose consumption, lactate production, and mitochondrial membrane potential. High-dose thiamine and DCA did not increase ROS, but increased caspase-3 activity.

CONCLUSION

Our findings suggest that high-dose thiamine reduces cancer cell proliferation by a mechanism similar to that described for dichloroacetate.

The protective effect of thiamine pyrophosphate, but not thiamine, against cardiotoxicity induced with cisplatin in rats

This study investigated the effect of thiamine pyrophosphate on oxidative damage associated with cardiotoxicity caused by cisplatin (CIS), an antineoplastic agent, in rats, and compared this with thiamine. Animals used in the study were divided into four groups of 6 rats each. These represented a control group receiving 5 mg/kg of CIS, study groups receiving 20 mg/kg of thiamine pyrophosphate plus 5 mg/kg of cisplatin (CTPG) or 20 mg/kg of thiamine plus 5 mg/kg of cisplatin and a healthy (H) group. All doses were administered intraperitoneally once a day for 14 days. Malondialdehyde, total glutathione and products of DNA injury results were similar in the CTPG and H groups (p > 0.05). Creatinine kinase, creatine kinase MB and troponin 1 levels were similar in the CTPG and H groups (p > 0.05). Thiamine pyrophosphate prevented CIS-associated oxidative stress and heart injury, whereas thiamine did not prevent these.

Thiamin diphosphate-dependent enzymes: from enzymology to metabolic regulation, drug design and disease models

Bringing a knowledge of enzymology into research in vivo and in situ is of great importance in understanding systems biology and metabolic regulation. The central metabolic significance of thiamin (vitamin B1 ) and its diphosphorylated derivative (thiamin diphosphate; ThDP), and the fundamental differences in the ThDP-dependent enzymes of metabolic networks in mammals versus plants, fungi and bacteria, or in health versus disease, suggest that these enzymes are promising targets for biotechnological and medical applications. Here, the in vivo action of known regulators of ThDP-dependent enzymes, such as synthetic structural analogs of the enzyme substrates and thiamin, is analyzed in light of the enzymological data accumulated during half a century of research. Mimicking the enzyme-specific catalytic intermediates, the phosphonate analogs of 2-oxo acids selectively inhibit particular ThDP-dependent enzymes. Because of their selectivity, use of these compounds in cellular and animal models of ThDP-dependent enzyme malfunctions improves the validity of the model and its predictive power when compared with the nonselective and enzymatically less characterized oxythiamin and pyrithiamin. In vitro studies of the interaction of thiamin analogs and their biological derivatives with potential in vivo targets are necessary to identify and attenuate the analog selectivity. For both the substrate and thiamin synthetic analogs, in vitro reactivities with potential targets are highly relevant in vivo. However, effective concentrations in vivo are often higher than in vitro studies would suggest. The significance of specific inihibition of the ThDP-dependent enzymes for the development of herbicides, antibiotics, anticancer and neuroprotective strategies is discussed.

Inhibition of transketolase by oxythiamine altered dynamics of protein signals in pancreatic cancer cells

Oxythiamine (OT), an analogue of anti-metabolite, can suppress the nonoxidative synthesis of ribose and induce cell apoptosis by causing a G1 phase arrest in vitro and in vivo. However, the molecular mechanism remains unclear yet. In the present study, a quantitative proteomic analysis using the modified SILAC method (mSILAC) was performed to determine the effect of metabolic inhibition on dynamic changes of protein expression in MIA PaCa-2 cancer cells treated with OT at various doses (0 μM, 5 μM, 50 μM and 500 μM) and time points (0 h, 12 h and 48 h). A total of 52 differential proteins in MIA PaCa-2 cells treated with OT were identified, including 14 phosphorylated proteins. Based on the dynamic expression pattern, these proteins were categorized in three clusters, straight down-regulation (cluster 1, 37% of total proteins), upright "V" shape expression pattern (cluster 2, 47.8% total), and downright "V" shape pattern (cluster 3, 15.2% total). Among them, Annexin A1 expression was significantly down-regulated by OT treatment in time-dependent manner, while no change of this protein was observed in OT dose-dependent fashion. Pathway analysis suggested that inhibition of transketolase resulted in changes of multiple cellular signaling pathways associated with cell apoptosis. The temporal expression patterns of proteins revealed that OT altered dynamics of protein expression in time-dependent fashion by suppressing phosphor kinase expression, resulting in cancer cell apoptosis. Results from this study suggest that interference of single metabolic enzyme activity altered multiple cellular signaling pathways.

Linking vitamin B1 with cancer cell metabolism

The resurgence of interest in cancer metabolism has linked alterations in the regulation and exploitation of metabolic pathways with an anabolic phenotype that increases biomass production for the replication of new daughter cells. To support the increase in the metabolic rate of cancer cells, a coordinated increase in the supply of nutrients, such as glucose and micronutrients functioning as enzyme cofactors is required. The majority of co-enzymes are water-soluble vitamins such as niacin, folic acid, pantothenic acid, pyridoxine, biotin, riboflavin and thiamine (Vitamin B1). Continuous dietary intake of these micronutrients is essential for maintaining normal health. How cancer cells adaptively regulate cellular homeostasis of cofactors and how they can regulate expression and function of metabolic enzymes in cancer is underappreciated. Exploitation of cofactor-dependent metabolic pathways with the advent of anti-folates highlights the potential vulnerabilities and importance of vitamins in cancer biology. Vitamin supplementation products are easily accessible and patients often perceive them as safe and beneficial without full knowledge of their effects. Thus, understanding the significance of enzyme cofactors in cancer cell metabolism will provide for important dietary strategies and new molecular targets to reduce disease progression. Recent studies have demonstrated the significance of thiamine-dependent enzymes in cancer cell metabolism. Therefore, this review discusses the current knowledge in the alterations in thiamine availability, homeostasis, and exploitation of thiamine-dependent pathways by cancer cells.

Thiol redox sensitivity of two key enzymes of heme biosynthesis and pentose phosphate pathways: uroporphyrinogen decarboxylase and transketolase

Uroporphyrinogen decarboxylase (Hem12p) and transketolase (Tkl1p) are key mediators of two critical processes within the cell, heme biosynthesis, and the nonoxidative part of the pentose phosphate pathway (PPP). The redox properties of both Hem12p and Tkl1p from Saccharomyces cerevisiae were investigated using proteomic techniques (SRM and label-free quantification) and biochemical assays in cell extracts and in vitro with recombinant proteins. The in vivo analysis revealed an increase in oxidized Cys-peptides in the absence of Grx2p, and also after treatment with H₂O₂ in the case of Tkl1p, without corresponding changes in total protein, demonstrating a true redox response. Out of three detectable Cys residues in Hem12p, only the conserved residue Cys52 could be modified by glutathione and efficiently deglutathionylated by Grx2p, suggesting a possible redox control mechanism for heme biosynthesis. On the other hand, Tkl1p activity was sensitive to thiol redox modification and although Cys622 could be glutathionylated to a limited extent, it was not a natural substrate of Grx2p. The human orthologues of both enzymes have been involved in certain cancers and possess Cys residues equivalent to those identified as redox sensitive in yeast. The possible implication for redox regulation in the context of tumour progression is put forward.

The effect of thiamine and thiamine pyrophosphate on oxidative liver damage induced in rats with cisplatin

The aim of this study was to investigate the effect of thiamine and thiamine pyrophosphate (TPP) on oxidative stress induced with cisplatin in liver tissue. Rats were divided into four groups; thiamine group (TG), TPP + cisplatin group (TPG), healthy animal group (HG), and cisplatin only group (CG). Oxidant and antioxidant parameters in liver tissue and AST, ALT, and LDH levels in rat sera were measured in all groups. Malondialdehyde levels in the CG, TG, TPG, and HG groups were 11 ± 1.4, 9 ± 0.5, 3 ± 0.5, and 2.2 ± 0.48  μ mol/g protein, respectively. Total glutathione levels were 2 ± 0.7, 2.8 ± 0.4, 7 ± 0.8, and 9 ± 0.6 nmol/g protein, respectively. Levels of 8-OH/Gua, a product of DNA damage, were 2.7 ± 0.4 pmol/L, 2.5 ± 0.5, 1.1 ± 0.3, and 0.9 ± 0.3 pmol/L, respectively. A statistically significant difference was determined in oxidant/antioxidant parameters and AST, ALT, and LDH levels between the TPG and CG groups (P < 0.05). No significant difference was determined between the TG and CG groups (P > 0.05). In conclusion, cisplatin causes oxidative damage in liver tissue. TPP seems to have a preventive effect on oxidative stress in the liver caused by cisplatin.

Epicatechin gallate impairs colon cancer cell metabolic productivity

Green tea and grape phenolics inhibit cancer growth and modulate cellular metabolism. Targeting the tumor metabolic profile is a novel therapeutic approach to inhibit cancer cell proliferation. Therefore, we treated human colon adenocarcinoma HT29 cells with the phenolic compound epicatechin gallate (ECG), one of the main catechins in green tea and the most important catechin in grape extracts, and evaluated its antiproliferation effects. ECG reduced tumor viability and induced apoptosis, necrosis, and S phase arrest in HT29 cells. Later, biochemical determinations combined with mass isotopomer distribution analysis using [1,2-(13)C2]-D-glucose as a tracer were used to characterize the metabolic network of HT29 cells in response to different concentrations of ECG. Glucose consumption was importantly decreased after ECG treatment. Moreover, metabolization of [1,2-(13)C2]-D-glucose indicated that the de novo synthesis of fatty acids and the pentose phosphate pathway were reduced in ECG-treated cells. Interestingly, ECG inhibited the activity of transketolase and glucose-6-phosphate dehydrogenase, the key enzymes of the pentose phosphate pathway. Our data point to ECG as a promising chemotherapeutic agent for the treatment of colon cancer.

An investigation of the effect of thiamine pyrophosphate on cisplatin-induced oxidative stress and DNA damage in rat brain tissue compared with thiamine

This study investigated the effects of thiamine pyrophosphate (TPP) at dosages of 10 and 20 mg/kg on oxidative stress induced in rat brain tissue with cisplatin and compared this with thiamine. Cisplatin neurotoxicity represents one of the main restrictions on the drug being given in effective doses. Oxidative stress is considered responsible for cisplatin toxicity. Our results showed that cisplatin increased the levels of oxidant parameters such as lipid peroxidation (thio barbituric acid reactive substance (TBARS)) and myeloperoxidase (MPO) in brain tissue and suppressed the effects of antioxidants such as total glutathione (GSH) and superoxide dismutase (SOD). TPP, especially at a dosage of 20 mg/kg, significantly reduced TBARS and MPO levels that increase with cisplatin administration compared with the thiamine group, while TPP significantly increases GSH and SOD levels. In addition, the level of 8-Gua (guanine), a product of DNA damage, was 1.7 ± 0.12 8-hydroxyl guanine (8-OH Gua)/105 Gua in brain tissue in the control group receiving cisplatin, compared with 0.97 ± 0.03 8-OH Gua/105 Gua in the thiamine pyrophosphate (20 mg/kg) group and 1.55 ± 0.11 8-OH Gua/105 Gua in the thiamine (20 mg/kg) group. These results show that thiamine pyrophosphate significantly prevents oxidative damage induced by cisplatin in brain tissue, while the protective effect of thiamine is insignificant.

Targeting cell cycle regulation in cancer therapy

Cell proliferation is an essential mechanism for growth, development and regeneration of eukaryotic organisms; however, it is also the cause of one of the most devastating diseases of our era: cancer. Given the relevance of the processes in which cell proliferation is involved, its regulation is of paramount importance for multicellular organisms. Cell division is orchestrated by a complex network of interactions between proteins, metabolism and microenvironment including several signaling pathways and mechanisms of control aiming to enable cell proliferation only in response to specific stimuli and under adequate conditions. Three main players have been identified in the coordinated variation of the many molecules that play a role in cell cycle: i) The cell cycle protein machinery including cyclin-dependent kinases (CDK)-cyclin complexes and related kinases, ii) The metabolic enzymes and related metabolites and iii) The reactive-oxygen species (ROS) and cellular redox status. The role of these key players and the interaction between oscillatory and non-oscillatory species have proved essential for driving the cell cycle. Moreover, cancer development has been associated to defects in all of them. Here, we provide an overview on the role of CDK-cyclin complexes, metabolic adaptations and oxidative stress in regulating progression through each cell cycle phase and transitions between them. Thus, new approaches for the design of innovative cancer therapies targeting crosstalk between cell cycle simultaneous events are proposed.

Is transketolase-like protein, TKTL1, transketolase?

Until recently it was assumed that the transketolase-like protein (TKTL1) detected in the tumor tissue, is catalytically active mutant form of human transketolase (hTKT). Human TKT shares 61% sequence identity with TKTL1. And the two proteins are 77% homologous at the amino acid level. The major difference is the absence of 38 amino acid residues in the N-terminal region of TKTL1. Site-specific mutagenesis was used for modifying hTKT gene; the resulting construct had a 114-bp deletion corresponding to a deletion of 38 amino acid residues in hTKT protein. Wild type hTKT and mutant variant (DhTKT) were expressed in Escherichia coli and isolated using Ni-agarose affinity chromatography. We have demonstrated here that DhTKT is devoid of transketolase activity and lacks bound thiamine diphosphate (ThDP). In view of these results, it is unlikely that TKTL1 may be a ThDP-dependent protein capable of catalyzing the transketolase reaction, as hypothesized previously.