RESUMO
Cancer-induced cachexia, characterized by systemic inflammation, body weight loss, adipose tissue (AT) remodeling and muscle wasting, is a malignant metabolic syndrome with undefined etiology. Here, we show that both genetic ablation and pharmacological inhibition of TLR4 were able to attenuate the main clinical markers of cachexia in mice bearing Lewis lung carcinoma (LLC). AT remodelling was not found in LLC tumor-bearing (TB) TLR4-/- mice due to reduced macrophage infiltration and adipocyte atrophy. TLR4-/- mice were also resistant to cold-induced browning of subcutaneous AT (scAT). Importantly, pharmacological inhibition of TLR4 (Atorvastatin) reproduced the main protective effect against AT remodeling found in TLR4-/- TB mice. Moreover, the treatment was effective in prolonging survival and attenuating tumor mass growth when compared to non-treated-TB animals. Furthermore, tumor-induced elevation of circulating pro-inflammatory cytokines was similarly abolished in both genetic ablation and pharmacological inhibition of TLR4. These data suggest that TLR4 is a critical mediator and a promising target for novel anti-cachexia therapies.
Assuntos
Tecido Adiposo/metabolismo , Caquexia/genética , Caquexia/mortalidade , Neoplasias/genética , Neoplasias/mortalidade , Receptor 4 Toll-Like/genética , Células 3T3-L1 , Tecido Adiposo/efeitos dos fármacos , Tecido Adiposo/patologia , Adiposidade/efeitos dos fármacos , Adiposidade/genética , Animais , Atorvastatina/farmacologia , Caquexia/etiologia , Caquexia/metabolismo , Carcinoma Pulmonar de Lewis/genética , Carcinoma Pulmonar de Lewis/mortalidade , Carcinoma Pulmonar de Lewis/patologia , Modelos Animais de Doenças , Deleção de Genes , Metabolismo dos Lipídeos/efeitos dos fármacos , Metabolismo dos Lipídeos/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neoplasias/complicações , Neoplasias/metabolismo , Análise de Sobrevida , Síndrome , Receptor 4 Toll-Like/antagonistas & inibidores , Células Tumorais CultivadasRESUMO
Cancer cachexia is a multifactorial syndrome characterized by body weight loss, atrophy of adipose tissue (AT) and systemic inflammation. However, there is limited information regarding the mechanisms of immunometabolic response in AT from cancer cachexia. Male Wistar rats were inoculated with 2 × 107 of Walker 256 tumor cells [tumor bearing (TB) rats]. The mesenteric AT (MeAT) was collected on d 0, 4, 7 (early stage), and 14 (cachexia stage) after tumor cell injection. Surgical biopsies for MeAT were obtained from patients who had gastrointestinal cancer with cachexia. Lipolysis showed an early decrease in glycerol release in TB d 4 (TB4) rats in relation to the control, followed by a 6-fold increase in TB14 rats, whereas de novo lipogenesis was markedly lower in the incorporation of glucose into fatty acids in TB14 rats during the development of cachexia. CD11b and CD68 were positive in TB7 and TB14 rats, respectively. In addition, we found cachexia stage results similar to those of animals in MeAT from patients: an increased presence of CD68+, iNOS2+, TNFα+, and HSL+ cells. In summary, translational analysis of MeAT from patients and an animal model of cancer cachexia enabled us to identify early disruption in Adl turnover and subsequent inflammatory response during the development of cancer cachexia.-Henriques, F. S., Sertié, R. A. L., Franco, F. O., Knobl, P., Neves, R. X., Andreotti, S., Lima, F. B., Guilherme, A., Seelaender, M., Batista, M. L., Jr. Early suppression of adipocyte lipid turnover induces immunometabolic modulation in cancer cachexia syndrome.
Assuntos
Adipócitos/metabolismo , Tecido Adiposo/metabolismo , Caquexia/etiologia , Caquexia/metabolismo , Metabolismo dos Lipídeos , Neoplasias/complicações , Neoplasias/metabolismo , Animais , Ácidos Graxos/metabolismo , Inflamação/metabolismo , Metabolismo dos Lipídeos/fisiologia , Masculino , Ratos WistarRESUMO
Angiotensin II (Ang II) increases the cytosolic Ca2+ concentration in different cell types. In this study, we investigate the effect of Ang II on the Ca2+ ATPase of purified basolateral membranes of kidney proximal tubules. This enzyme pumps Ca2+ out of the cytosol in a reaction coupled to ATP hydrolysis, and it is responsible for the fine-tuned regulation of cytosolic Ca2+ activity. Ca2+-ATPase activity is inhibited by picomolar concentrations of Ang II, with maximal inhibition being attained at approximately 50% of the control values. The presence of raising concentrations (10(-11) to 10(-7) M) of losartan (an AT1-receptor antagonist) or PD123319 (an AT2-receptor antagonist) gradually reverts inhibition by Ang II. Both the phospholipase C (PLC) inhibitor U-73122 (10(-6) M) and the inhibitor of protein kinase C (PKC) staurosporine (10(-7) M) prevent inhibition of the Ca2+ pump by Ang II. Incubation of the previously isolated membranes with a PKC activator-the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (10(-8) M)-mimics the inhibition found with Ang II, and the effects of the compounds are not additive. Taken as a whole, these results indicate the Ang II inhibits Ca2+-ATPase by activation of a PKC system present in primed state in these membranes after binding of the hormone to losartan- and PD123319-sensitive receptors coupled to a PLC. Therefore, inhibition of the basolateral membrane Ca2+-ATPase by kinase-mediated phosphorylation appears to be one of the pathways by which Ang II promotes an increase in the cytosolic Ca2+ concentration of proximal tubule cells.
Assuntos
Bloqueadores do Receptor Tipo 1 de Angiotensina II/farmacologia , Bloqueadores do Receptor Tipo 2 de Angiotensina II , Angiotensina II/farmacologia , ATPases Transportadoras de Cálcio/metabolismo , Túbulos Renais Proximais , Proteína Quinase C/metabolismo , Receptor Tipo 1 de Angiotensina/metabolismo , Animais , Células Cultivadas , Relação Dose-Resposta a Droga , Imidazóis/farmacologia , Túbulos Renais Proximais/citologia , Túbulos Renais Proximais/efeitos dos fármacos , Túbulos Renais Proximais/enzimologia , Losartan/farmacologia , Piridinas/farmacologia , Receptor Tipo 2 de Angiotensina/metabolismo , Ovinos , Vasoconstritores/farmacologiaRESUMO
Plasma membrane Ca2+-ATPase is involved in the fine-tuned regulation of intracellular Ca2+. In this study, the presence of Ca2+-ATPase in caveolae from kidney basolateral membranes was investigated. With the use of a discontinuous sucrose gradient, we show that Ca2+-ATPase is exclusively located and fully active in caveolin-containing microdomains. Treatment with methyl-beta-cyclodextrin--a cholesterol chelator--leads to a spreading of both caveolin and completely inactive Ca2+-ATPase toward high-density fractions. These data support the view that Ca2+ fluxes mediated by Ca2+-ATPase in kidney epithelial cells occur only in caveolae, being strictly dependent on the integrity of these microdomains.
Assuntos
ATPases Transportadoras de Cálcio/metabolismo , Cavéolas/enzimologia , Membrana Celular/enzimologia , Túbulos Renais Proximais/química , Animais , Western Blotting , Cálcio/metabolismo , Calmodulina/metabolismo , Caveolinas/química , Eletroforese em Gel de Poliacrilamida , Microdomínios da Membrana/química , Modelos Biológicos , SuínosRESUMO
Sphingosine-1-phosphate (S1P) and phosphatidylinositol-4 phosphate [PtdIns(4)P] are important second messengers in various cellular processes. Here, we show that S1P and PtdIns(4)P are formed in purified basolateral membranes (BLM) derived from kidney proximal tubules, indicating the presence of a plasma membrane associated SPK (BLM-SPK) and phosphatidylinositol-4 kinase (PI-4K). We observed that S1P synthesis is linear with time, dependent on protein concentration, and saturable in the presence of increasing concentrations of sphingosine. Different from the observations on cytosolic SPKs, the formation of S1P by BLM-SPK is Mg(2+)-independent and insensitive to the classical inhibitor of the cytosolic SPKs, DL-threo-dihydrosphingosine. With sphingosine as substrate, the enzyme shows cooperative kinetics (n = 3.4) with a K(0.5) value of 0.12 mM, suggesting that BLM-SPK is different from the previously characterized cytosolic SPK. The formation of PtdIns(4)P markedly inhibits BLM-SPK activity. Conversely, a strong activation of PtdIns(4)P synthesis by the formation of S1P is observed. Taken together, these results indicate that (i) basolateral membranes from kidney cells harbor a SPK activity that potentially regulates renal epithelium function, and (ii) the formation of S1P mediated by SPK enhances PI-4K activity, while PtdIns(4)P in turn inhibits SPK, suggesting an interplay between these lipid signaling molecules. These findings suggest the possibility of crosstalk between sphingolipids and glycerolipids, which might be involved in the regulation of transepithelial fluxes across the BLM of kidney cells.