Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A ação inibitória dos organofosforados sobre as esterases, por ser específica, pode ser empregada como um eficiente biomarcador da exposição de seres vivos aos organofosforados. A inibição da acetilcolinesterase (AChE; EC 3.1.1.7) provoca acúmulo do neurotransmissor acetilcolina nas fendas sinápticas colinérgicas, o que pode resultar na morte do indivíduo. Outra atividade também afetada por organofosforados é a da enzima carboxilesterase (CarbE; EC 3.1.1.1). CarbE estão envolvidas na fase I da biotransformação de xenobióticos e atuam como captadoras (scavengers) de organofosfatos, incluindo os formados pela biotransformação dos organofosforados. As CarbE estudadas até hoje se ligam com maior velocidade aos organofosfatos do que as colinesterases. Por isto se admite que CarbE possam diminuir, por captação estequiométrica, a ligação tóxica de moléculas de organofosfatos às acetilcolinesterases das sinapses colinérgicas e das placas motoras dos músculos. Experimentos realizados em nosso laboratório mostraram que a atividade da CarbE está aproximadamente 50% menor no soro e no fígado de pacus submetidos à hipoxia. Por causa disso, em razão de uma possível diminuição da capacidade captadora da CarbE, decidimos verificar se o pacu em hipoxia seria mais sensível aos agrotóxicos organofosforados. Para este propósito foram colocados seis pacus divididos em dois tanques. No primeiro tanque, os animais foram submetidos a 24 horas de hipoxia seguidos por mais 4 horas de exposição ao organofosforado metilparation em duas concentrações diferentes (0,02 ou 0,01 mg / L). No segundo tanque os animais permaneceram em normoxia durante o mesmo período de 24 horas e depois foram expostos ao metilparation como no primeiro tanque. As atividades da AChE ensaiada com acetiltiocolina, a da butirilcolinesterase (BChE) ensaiada com butiriltiocolina e a da CarbE ensaiada com p-nitrofenilacetato foram avaliadas no soro, fígado, cérebro, músculo e coração dos pacus. Houve redução de aproximadamente 35% da atividade de CarbE no soro dos pacus submetidos a 24 horas de hipoxia. Uma queda de 85% na atividade de CarbE do soro foi observada nos animais que sofreram hipoxia e subsequente exposição a 0,02 mg de metilparation por litro. Com metilparation a 0,01 mg/L a diminuição observada foi de 48,2%. No músculo dos pacus expostos a 0,02 mg/L, as atividades de AChE e BChE cairam pela metade quando os mesmos foram submetidos à hipoxia quando comparados a animais que permaneceram em normoxia. Nos diversos tecidos dos pacus expostos a 0,01 mg/L de metilparation não observamos diferenças significativas nas atividades de AChE, BChE ou CarbE. Concluímos que a duplicação da concentração de metilparation de 0,01 para 0,02 mg/L levou à atividade residual de CarbE do soro de 51,8% para 15%. A ausência de mudanças nas atividades das esterases dos tecidos de animais expostos a 0,01 mg/L entre os grupos hipoxia e normoxia deve ter ocorrido porque a concentração de organofosforado não foi suficiente para superar a primeira barreira de proteção das esterases séricas e atingir os tecidos. Mas, no experimento com 0,02 mg/L de metilparation, as inibições de AChE e de BChE no músculo dos animais em hipoxia podem ser explicadas pela diminuição da atividade de CarbE do soro dos pacus. / The inhibitory action of organophosphates on cholinesterases is a specific phenomenon, and it is used as a biomarker of exposure to organophosphate in live animals. Inhibition of cholinesterases results in the accumulation of acetylcholine in the synaptic clefts of cholinergic synapses, which can lead to death. Another enzyme which is affected by organophosphates is the carboxylesterase (CarbE). CarbE are involved in phase I of xenobiotic biotransformation and can act as a "scavenger" of organophosphates. The CarbE studied to the present date can bond to organophosphate with greater speed than other cholinesterases. Therefore, CarbE might decrease by stoichiometric uptake the binding of organophosphate at the acetylcholinesterase at cholinergic synapses and motor end plates of muscles. Experiments conducted in our laboratory showed that the CarbE activity is about 50% lower in serum and liver of pacu subjected to hypoxia. Due to the detoxifying role of CarbE we verified whether pacu, under conditions of oxidative stress, would be more sensitive to organophosphate pesticides. Nine pacus were divided into two tanks. In the first tank the animals underwent 24 hours of hypoxia followed by a further 4 hours of exposure to methylparathion in two different concentrations (0,02 or 0,01 mg/L). Thus, in the second tank the animals remained in normoxia for 24 hours and were subsequently exposed to methylparathion for 4 hours. The activities of acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and CarbE were tested in serum, liver, brain, muscle and heart. We found a decrease of approximately 35% of CarbE activity in serum of the animals subjected to 24 hours of hypoxia. A fall of 85% in CarbE activity was detected in the serum of animals that suffered hypoxia and subsequent exposure to 0,02 mg/L, yet in animals exposed to 0,01 mg/L there is a decrease of 48,2%. In muscle the activities of AChE and BChE declined by half in animals submitted to hypoxia compared with animals in normoxia when exposed to 0,02 mg/L. In the tissues of pacus exposed to 0,01 mg/L of methylparathion we did not observe significant differences in the activities of AChE, BChE or CarbE. We concluded that doubling the concentration of methylparathion from 0,01 to 0,02 mg/L causes CarbE activity in the serum to decrease from 51,8% to 15%. The absence of changes in activities in the tissues of animals exposed to 0,01 mg/L between the groups hypoxia and normoxia may have occurred because the concentration of methylparathion was not sufficient to break the first enzymes barrier of protection in serum. In the experiment with 0,02 mg/L of methylparathion the activities of AChE and BChE in the muscle were most inhibited in the hypoxia group than the normoxia group. This phenomenon can be explained by the decrease in the CarbE activity in the serum of animals under hypoxia.

abstract: Patients with malignant brain tumors have a median survival of approximately 15 months following diagnosis, regardless of currently available treatments which include surgery followed by radiation and chemotherapy. Improvement in the survival of brain cancer patients requires the design of new therapeutic modalities that take advantage of common phenotypes. One such phenotype is the metabolic dysregulation that is a hallmark of cancer cells. It has therefore been postulated that one approach to treating brain tumors may be by metabolic alteration such as that which occurs through the use of the ketogenic diet (KD). The KD is high-fat, low-carbohydrate diet that induces ketosis and has been utilized for the non-pharmacologic treatment of refractory epilepsy. It has been shown that this metabolic therapy enhances survival and potentiates standard therapy in mouse models of malignant gliomas, yet the anti-tumor mechanisms are not fully understood. The current study reports that KetoCal® (KC; 4:1 fat:protein/carbohydrates), fed ad libitum, alters hypoxia, angiogenic, and inflammatory pathways in a mouse model of glioma. Tumors from animals maintained on KC showed reduced expression of the hypoxia marker carbonic anhydrase 9 (CA IX), a reduction in hypoxia inducible factor 1-alpha (HIF-1α) and decreased activation of nuclear factor kappa B (NF-κB). Animals maintained on KC also showed a reduction in expression of vascular endothelial growth factor receptor 2 (VEGFR2) and decreased microvasculature in their tumors. Further, peritumoral edema was significantly reduced in animals fed the KC and protein analysis showed significantly altered expression of the tight junction protein zona occludens-1 (ZO-1) and the water channeling protein aquaporin-4 (AQP4), both of which have been implicated in malignant processes in glioma, including the formation of peritumoral edema in patients. Taken together the data suggests that KC alters multiple processes involved in malignant progression of gliomas. A greater understanding of the effects of the ketogenic diet as an adjuvant therapy will allow for a more rational approach to its clinical use. / Dissertation/Thesis / Masters Thesis Biology 2014

Muitos animais enfrentam situações de baixa pressão parcial de oxigênio (hipóxia) ao longo da vida, seja por condições ambientais (tocas, altas altitudes) ou clínicas (insuficiência cardíaca, respiratória ou metabólica). Sabe-se que a queda regulada da temperatura corporal (Tc), chamada anapirexia, induzida pela hipóxia tem tanto importância fisiológica quanto para a clínica, entretanto apenas nas últimas décadas alguns pesquisadores têm se dedicado mais intensamente ao estudo dos mecanismos envolvidos neste fenômeno. Estes estudos, em geral, não levaram em conta a fase do dia durante a realização dos experimentos nem durante a análise dos resultados. Considerando que a Tc apresenta um ritmo diário e circadiano com padrão robusto, é possível que a anapirexia seja alterada de acordo com o momento do dia em que o animal é exposto à hipóxia. Diante disso, tal hipótese foi testada no presente estudo e, para isso, os animais foram expostos à hipóxia em diferentes fases do dia e foi registrada a Tc, o consumo de oxigênio (VO2) e o índice de perda de calor (IPC). Estes protocolos foram realizados sob duas temperaturas ambientes (Tas; 26 e 19°C), pois se sabe que a anapirexia também pode ser alterada pela Ta. Em ambas Tas, foi visto que animais expostos à hipóxia no início da fase de escuro apresentam amplitude maior de queda de Tc em relação àqueles expostos no início da fase de claro e, tal diferença deve-se, ao menos em parte, à inibição induzida pela hipóxia da maior termogênese encontrada nestes animais durante a noite. O IPC mensurado no final do intervalo hipóxico parece não ter muita importância para as diferenças nas respostas anapiréticas. Além disso, todas as amplitudes anapiréticas foram maiores nos animais testados sob o frio, independente da fase do dia. Assim, os resultados indicam que a fase do dia interfere na anapirexia induzida por hipóxia aguda e que essa resposta é maior em menores Tas em qualquer momento do dia. / Several animals face reduced oxygen partial pressure (hypoxia) throughout their lives, due to environmental (burrows, high altitudes) or clinical conditions (cardiac, respiratory or metabolic failures). Its known that the hypoxia-induced decrease in body temperature (Tb), named anapyrexia, is a regulated process of adaptive importance. However only in the past few decades researchers have been studied the mechanisms involved in this phenomenon. These studies, in general, did not take the phase of the day into account during the experiments or during the analyses of their results. Considering that Tb shows circadian and diary rhythm with a robust pattern, it is possible that anapyrexia can be altered depending on to the moment of the day in which the animal is exposed to hypoxia. Thus, the present study tested this hypothesis exposing animals to hypoxia in different phases of Day and Tb, oxygen consumption (VO2) and heat loss index (HLI) were measured. These protocols were conducted in two ambient temperatures (Tas; 26°C and 19°C), because it is known that anapyrexia can be altered by Ta. In both Tas, it was observed that animals exposed to hypoxia during the beginning of the dark phase presented bigger anapyrexic amplitude than those exposed during the beginning of the light phase. This difference may be due, at least in part, to the inhibition induced by hypoxia of the biggest thermogenesis found during dark phase. HLI measured at the end of the hypoxia exposure seems to have no influence in the different anapyretic responses. Moreover, the cold condition induced bigger anapyretic responses independent on the phase of day. Thus, the results indicate the phase of day influences the hypoxia-induced anapyrexia and this response is bigger in lower ambient temperatures at any moment of the light-dark cycle.

Orientador: Antonio Carlos de Moraes / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Educação Física / Made available in DSpace on 2018-08-21T22:00:45Z (GMT). No. of bitstreams: 1 Smirmaul_BrunodePaulaCaraca_M.pdf: 4243812 bytes, checksum: 6a170352ba2b6b469396a6dd7c5d13f5 (MD5) Previous issue date: 2013 / Resumo: Introdução: Apesar de ser uma substância extensivamente estudada no âmbito do desempenho físico, a cafeína e seus efeitos no desempenho em altitude (hipóxia) foram estudados em apenas 2 investigações científicas (Berglund & Hemmingsson 1982; Fulco et al 1994), sugerindo que esta tem seus efeitos potencializados nesse ambiente. As únicas variáveis analisadas foram percepção de esforço e parâmetros cardiorrespiratórios. Porém, um dos mecanismos de ação sugeridos da cafeína é no sistema neuromuscular que, em hipóxia, sofre com uma mais rápida ocorrência de fadiga. Objetivo: Investigar o efeito da cafeína no desempenho aeróbio em hipóxia nos parâmetros psicofisiológicos, em particular seus efeitos na fadiga periférica e central. Métodos: Sete sujeitos (29 ± 6 anos, 179 ± 8 cm, 75 ± 8 kg, VO2máx 51 ± 5 ml.kg-1) participaram desse estudo duplo-cego e randomizado. Primeiro realizaram um teste incremental máximo em hipóxia (FIO2 = 0,15) para determinar a potência pico. A segunda e terceira visita consistiu em um período fixo de 6 min de exercício, seguido de um teste constante até a exaustão, ambos a _80% da potência pico e em hipóxia. Lactato, SpO2, percepção de esforço, frequência cardíaca, e fadiga periférica e central foram mensuradas. Resultados: Durante o teste incremental, a potência pico alcançada foi de 275 ± 38 W, com valores finais de percepção de esforço, lactato, frequência cardíaca e SpO2 de 18 ± 1, 13 ± 2 mmol/l, 179 ± 10 bpm, e 81 ± 5%, respectivamente. Tempo até a exaustão foi significativamente maior (11,8%) na condição cafeína (402 ± 137 s) comparado à condição placebo (356 ± 112 s) (P = 0,016). Tempos individuais foram maiores com cafeína em 6 dos 7 sujeitos. Variação intra-sujeito foi de -5 a 23% (-10 a 74 s). Cafeína teve um impacto significativo na subescala de humor fadiga, apresentando menores valores, enquanto a subescala vigor apresentou tendência a ser maior nessa condição. A percepção de esforço apresentou menores valores para o grupo cafeína durante o teste até exaustão. Tanto para o período de 6 minutos como durante o teste de tempo até a exaustão, a frequência cardíaca foi maior para o grupo cafeína. Enquanto SpO2 foi menor para o grupo cafeína apenas durante o período de 6 minutos, os valores de lactato não diferiram entre os grupos, mas apresentaram tendência a maiores valores na condição cafeína. Os valores de contração voluntária máxima apresentaram declínio significativo, com maior queda para o grupo cafeína. Já os valores de ativação voluntária e estímulos duplos, apesar de decrescerem, não foram diferentes entre as condições. Por fim, todos os parâmetros de oxigenação não diferiram entre as condições. Conclusão: O efeito ergogênico da cafeína em altitude ocorreu concomitantemente a alterações no estado de humor, percepção de esforço, sinais eletromiográficos, frequência cardíaca e contração voluntária máxima / Abstract: Introduction: Despite being a substance extensively studied in the physical performance scope, caffeine and its effects on performance in altitude (hypoxia) have been studied only in 2 scientific investigations (Berglund & Hemmingsson 1982; Fulco et al 1994), and it is suggested that is has greater effects in this environment. The variables analyzed were only perception of effort and cardiorespiratory parameters. However, one of the suggested caffeine's mechanisms of action is upon the neuromuscular system that, in hypoxia, presents a faster development of fatigue. Aim: Study the effects of caffeine during aerobic performance in hypoxia in the psychophysiological parameters, in particular its effects on peripheral and central fatigue. Methods: Seven subjects (29 ± 6 years, 179 ± 8 cm, 75 ± 8 kg, VO2max 51 ± 5 ml.kg-1) participated in this randomized double-blind study. First it was performed a maximal incremental test in hypoxia (FIO2 = 0.15) to determine peak power output. The second and third visits consisted of a fixed period of 6 min of exercise, followed by a time to exhaustion test, both at _80% of peak power output and in hypoxia. Lactate, SpO2, perception of effort, heart rate, and peripheral and central fatigue were measured. Results: During the incremental test, peak power output reached was 275 ± 38 W, with end-values of perception of effort, lactate, heart rate and SpO2 of 18 ± 1, 13 ± 2 mmol/l, 179 ± 10 bpm, and 81 ± 5%, respectively. Time to exhaustion was significantly longer (11.8%) with caffeine (402 ± 137 s) compared to placebo (356 ± 112 s) (P = 0.016). Individual times were longer with caffeine in 6 out of 7 subjects. Intra-subject variability was from -5 to 23% (-10 to 74s). Caffeine had a significant impact on the mood subscale fatigue, presenting lower values, while the subscale vigor presented a trend to be higher in this condition. Perception of effort presented lower values in the caffeine condition during time to exhaustion test. Both to the fixed period of 6 minutes and to the time to exhaustion test, heart rate was higher in the caffeine condition. While SpO2 was lower with caffeine only during the fixed period of 6 minutes, lactates values did not differ between groups, but presented a trend to be higher during the caffeine condition. Values of maximal voluntary contraction showed a significant reduction, with greater reduction in the caffeine condition. However, voluntary activation and doublet values, despite decreasing, were not different between conditions. Finally, all the brain oxygenation parameters did not differ between conditions. Conclusion: The ergogenic effect of caffeine at altitude occurred concomitantly with alterations in mood state, perception of effort, electromyographic signals, heart rate and maximal voluntary contraction / Mestrado / Biodinamica do Movimento e Esporte / Mestre em Educação Física

Fatigue is defined as an exercise-induced decrease in maximal voluntary force produced by a muscle. Fatigue may arise from central and/or peripheral mechanisms. Supraspinal fatigue (a component of central fatigue) is defined as a suboptimal output from the motor cortex and measured using transcranial magnetic stimulation (TMS). Reductions in O2 supply (hypoxia) exacerbate fatigue and as the severity of hypoxia increases, central mechanisms of fatigue are thought to contribute more to exercise intolerance. In study 1, the feasibility of TMS to measure cortical voluntary activation and supraspinal fatigue of human knee-extensors was determined. TMS produced reliable measurements of cortical voluntary activation within- and between-days, and enabled the assessment of supraspinal fatigue. In study 2, the mechanisms of fatigue during single-limb exercise in normoxia (arterial O2 saturation [SaO2] ~98%), and mild to severe hypoxia (SaO2 93-80%) were determined. Hypoxia did not alter neuromuscular function or cortical voluntary activation of the knee-extensors at rest, despite large reductions in cerebral oxygenation. Maximal force declined by ~30% after single-limb exercise in all conditions, despite reduced exercise time in severe-hypoxia compared to normoxia (15.9 ± 5.4 vs. 24.7 ± 5.5 min; p < 0.05). Peripheral mechanisms of fatigue contributed more to the reduction in force generating capacity of the knee-extensors following single-limb exercise in normoxia and mild- to moderate-hypoxia, whereas supraspinal fatigue played a greater role in severe-hypoxia. In study 3, the effect of constant-load cycling exercise to the limit of tolerance in hypoxia (SaO2 ~80%) and normoxia was investigated. Time to the limit of tolerance was significantly shorter in hypoxia compared to normoxia (3.6 ± 1.3 vs. 8.1 ± 2.9 min; p < 0.001). The reductions in maximal voluntary force and knee-extensor twitch force at task-failure were not different in hypoxia compared to normoxia. However, the level of supraspinal fatigue was exacerbated in hypoxia, and occurred in parallel with reductions in cerebral oxygenation and O2 delivery. Supraspinal fatigue contributes to the decrease in whole-body exercise tolerance in hypoxia, presumably as a consequence of inadequate O2 delivery to the brain.

Chronic prenatal hypoxia is associated with intrauterine growth retardation and there is now some evidence that it also induces programmed hypertension in offspring. However these studies are generally confounded as hypoxia is either induced by maternal hypoxia or placental insufficiency. The study described in this thesis is designed to overcome this problem. Pregnant rats were dosed daily with the drug dofetilide (2.5 mg/kg) or water on GD 11-14 and the cardiovascular parameters of the offspring at 8-12 weeks (&gt;300g) were analysed using implanted telemetry blood pressure (BP) transmitters.Dofetilide is a class III antiarrhythmic drug that selectively blocks the Ikr channel which is expressed in the rat embryo but not in the adult rat. When administered to pregnant rats it induces bradycardia (and associated hypoxia) in the embryos without affecting maternal oxygenation or heart rate. Embryo culture studies showed that dofetilide induced a period of embryonic bradycardia for up to 9 hours following each dose. The dofetilide treated-rats had less completed pregnancies, smaller litters and lower weight pups compared to controls. At 8-12 weeks age the dofetilide offspring has increased BP (+10-12%) compared with controls. Postnatal stress in the form of air puffs did not reveal other cardiovascular differences between control and dofetilide offspring. The increased BP was not associated with an increased HR or changes in the autonomic nervous system. Remaining unexplored possibilities include impaired nephrogenesis, vascular dysfunction and microvascular

The search for the optimal choice of treatment time, dose and fractionation regimen is one of the major challenges in radiation therapy. Several aspects of the radiation response of tumours and normal tissues give different indications of how the parameters defining a fractionation schedule should be altered relative to each other which often results in contradictory conclusions. For example, the increased sensitivity to fractionation in late-reacting as opposed to early-reacting tissues indicates that a large number of fractions is beneficial, while the issue of accelerated repopulation of tumour cells starting at about three weeks into a radiotherapy treatment would suggest as short overall treatment time as possible. Another tumour-to-normal tissue differential relevant to the sensitivity as well as the fractionation and overall treatment time is the issue of tumour hypoxia and reoxygenation. The tumour oxygenation is one of the most influential factors impacting on the outcome of many types of treatment modalities. Hypoxic cells are up to three times as resistant to radiation as well-oxygenated cells, presenting a significant obstacle to overcome in radiotherapy as solid tumours often contain hypoxic areas as a result of their poorly functioning vasculature. Furthermore, the oxygenation is highly dynamic, with changes being observed both from fraction to  fraction and over a time period of weeks as a result of fast and slow reoxygenation of acute and chronic hypoxia. With an increasing number of patients treated with hypofractionated stereotactic body radiotherapy (SBRT), the clinical implications of a substantially reduced number of fractions and hence also treatment time thus have to be evaluated with respect to the oxygenation status of the tumour. One of the most promising tools available for the type of study aiming at determining the optimal radiotherapy approach with respect to fractionation is radiobiological modelling. With clinically validated in vitro-derived tissue-specific radiobiological parameters and well-established survival models, in silico modelling offers a wide range of opportunities to test various hypotheses with respect to time, dose, fractionation and details of the tumour microenvironment. Any type of radiobiological modelling study intended to provide a realistic representation of a clinical tumour should therefore take into account details of both the spatial and temporal tumour oxygenation. This thesis presents the results of three-dimensional radiobiological modelling of the response of tumours with heterogeneous oxygenation to various fractionation schemes, and oxygenation levels and dynamics using different survival models. The results of this work indicate that hypoxia and its dynamics play a major role in the outcome of radiotherapy, and that neglecting the oxygenation status of tumours treated with e.g. SBRT may compromise the treatment outcome substantially. Furthermore, the possibilities offered by incorporating modelling into the clinical routine are explored and demonstrated by the development of a new calibration function for converting the uptake of the hypoxia-PET tracer 18F-HX4 to oxygen partial pressure, and applying it for calculations of the doses needed to overcome hypoxia-induced radiation resistance. By hence demonstrating how the clinical impact of hypoxia on dose prescription and the choice of fractionation schedule can be investigated, this project will hopefully advance the evolution towards routinely incorporating functional imaging of hypoxia into treatment planning. This is ultimately expected to result in increased levels of local control with more patients being cured from their cancer. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 6: Manuscript.</p>

Abstract In mammalian cells the pH gradient between the organelles, cytoplasm and extracellular space is strictly regulated. Maintenance of pH homeostasis is crucial for the normal function of the cell and its organelles. In solid tumours, cells often suffer from hypoxia, deprivation of nutrients and acidic extracellular milieu as a result of inadequate vascularisation. Cancer cells are also known to suffer from other pH abnormalities. Defective acidification of intracellular organelles as well as a reversed pH gradient across the plasma membrane have been detected in numerous tumour tissues and cells. Aberrant secretion of lysosomal hydrolases, loss of cell polarity and increased expression of tumour-specific proteins are common phenotypic changes of cancer cells. In this study, secretion of cathepsin D, a lysosomal aspartic hydrolase, was shown to result from the acidification defect of cancer cells. In normal cells cathepsin D is sorted in the Golgi complex by mannose-6-phosphate receptors and transported via endosomes to lysosomes. In breast and colorectal cancer cells having abnormally neutral endosomes receptors were shown to accumulate in endosomes resulting in the aberrant secretion of newly synthesised cathepsin D from the cells. Carcinoembryonic antigen (CEA) is an oncofetal protein widely used as a tumour follow-up marker. It is normally expressed at low levels and is localised at the apical surface of epithelial cells via a glycosyl phosphatidyl inositol (GPI) anchor. In cancer cells the expression of CEA is increased and the protein is found over the entire surface of cells. In this study, the tumour microenvironmental factors, hypoxia and abnormal pH homeostasis, were shown to increase the expression of carcinoembryonic antigen in cancer cells. In addition, the absence of acidic organelles was shown to induce mistargeting of CEA to the basolateral membrane in polarised cells. The abnormally neutral Golgi was found to interfere with the complex formation of carcinoembryonic antigen, a phenomenon recently associated with the apical sorting of other GPI-anchored proteins. Altogether these results emphasise the role of tumour-related factors – altered pH homeostasis and hypoxia – in the phenotypic changes of cancer cells.

No description available.

Under normal conditions, non-transformed cells rely on glycolysis followed by oxidative phosphorylation to generate ATPs. When oxygen is scarce or when cells are actively proliferating, cellular ATPs come mainly from glycolysis. Pyruvate is converted into lactate to allow glycolysis to continue. Interestingly, cancer cells have adapted to favor lactate production even at normal oxygen tensions, exhibiting a metabolic shift known as the Warburg effect. However, the metabolic state of other cellular constituents within the tumor remains mostly unknown. Cancer-associated fibroblasts (CAFs) are the most abundant stromal cells. They aid tumor growth and metastasis by providing growth factors, cytokine, ECM remodeling proteins and interacting with other tumor stromal cells. Here I show that the Warburg effect also operates in stromal fibroblasts of the tumor microenvironment. Using mass spectrometry, genetic mouse models, gene expression and methylation studies, I demonstrate that CAFs from human and mouse mammary tumors exhibit hyperactive glycolysis and a metabolic shift towards lactate production. Furthermore, this phenotype may be sustained through epigenetic modifications of endogenous hypoxia-inducible factor 1α, key regulatory enzymes fructose-bisphosphatase 1 and pyruvate kinase M2. Depletion of stromal fibroblasts or suppression of lactate production specifically in these cells alters the metabolic profile of not only the tumors but also the cancer cells and results in impeded tumor growth. These results collectively suggest that tumor growth is dependent on metabolic state and metabolic support of stromal fibroblasts, highlighting these cells as attractive therapeutic targets in controlling cancer progression.