左旋肉碱通过调节脂代谢改善恶液质骨骼肌细胞萎缩

目的 探讨左旋肉碱是否能改善肿瘤恶液质的骨骼肌萎缩及可能的分子机制。方法 用100ng/ml 肿瘤坏死因子-α诱导小鼠C2C12成肌细胞萎缩建立肿瘤恶液质的骨骼肌减少的细胞模型,不同剂量左旋肉碱干预C2C12细胞肌纤维成熟过程;结晶紫染色观察各组肌纤维分化成熟状态,并通过Western Blot技术分析C2C12细胞内糖脂代谢相关蛋白的表达水平,探讨左旋肉碱能否改善骨骼肌细胞萎缩及可能的机制。结果 100μg/ml和1000μg/ml左旋肉碱干预能够促进C2C12细胞分化,抑制TNF-α诱导的肌纤维变细（P<0.001）。TNF-α组与对照组比较,肌细胞脂质代谢、糖代谢相关蛋白中 CPT-Ⅰ和PGC-1α表达下降,FOXO1、CD36以及PDK4的表达升高。左旋肉碱干预促进CPT-Ⅰ和PGC-1α的表达增加,抑制了FOXO1、CD36的表达,但对PDK4的表达无影响。结论 左旋肉碱可能通过调节肌细胞脂代谢来改善细胞肿瘤恶液质。     

L-carnitine and cancer cachexia. I. L-carnitine distribution and metabolic disorders in cancer cachexia

Cancer cachexia (CC), a progressive loss of body mass, is associated with decreased energy production. Abnormally low levels of L-carnitine (LC) in skeletal muscle means that mitochondrial β-oxidation of long-chain fatty acids (LCFA) does not occur efficiently in patients with CC. We assessed the influence of CC on LC distribution and the effects of parenteral lipid emulsions on plasma LC levels and urinary excretion. Fifty patients with CC were randomly assigned to total parenteral nutrition (TPN) with long-chain triglycerides (LCTs), or LCTs plus medium-chain triglycerides (MCTs) as 50/50. Patients were further separated into those with body-mass index (BMI) ≤ 19 kg/m(2) and BMI >19 kg/m(2). Plasma concentrations of total LC (TC) and free LC (FC) and their urinary excretion were measured, along with skeletal muscle LC levels. On average, plasma FC and TC were higher than reference values in all patients. Patients with BMI ≤ 19 kg/m(2) had lower plasma FC and TC than those with BMI >19 kg/m(2). Skeletal muscle FC in the BMI ≤ 19 kg/m(2) group was lower than reference value, but within the normal range in others. LC and FC urinary excretion was higher than reference values. Plasma LC and its urinary excretion were higher in patients administered pure LCTs relative to those given MCTs/LCTs. A decrease in skeletal muscle LC in cancer patients with CC (BMI ≤ 19 kg/m(2)) correlates with an increase in its plasma levels and increased renal excretion. A diet of MCTs/LCTs reduces LC release from muscle to plasma and urine more effectively than LCTs.     

Melatonin inhibits aromatase promoter expression by regulating cyclooxygenases expression and activity in breast cancer cells

Background:

Melatonin reduces the development of breast cancer interfering with oestrogen-signalling pathways, and also inhibits aromatase activity and expression. Our objective was to study the promoters through which melatonin modifies aromatase expression, evaluate the ability of melatonin to regulate cyclooxygenases and assess whether the effects of melatonin are related to its effects on intracellular cAMP, in MCF-7 cells.

Methods:

Total aromatase mRNA, aromatase mRNA promoter regions and cyclooxygenases mRNA expression were determined by real-time RT–PCR. PGE₂ and cAMP were measured by kits.

Results:

Melatonin downregulated the gene expression of the two major specific aromatase promoter regions, pII and pI.3, and also that of the aromatase promoter region pI.4. Melatonin 1 nM was able to counteract the stimulatory effect of tetradecanoyl phorbol acetate on PGE₂ production and inhibit COX-2 and COX-1 mRNA expression. Melatonin 1 nM elicited a parallel time-dependent decrease in both cyclic AMP formation and aromatase mRNA expression.

Conclusions:

This study shows that melatonin inhibits aromatase activity and expression by regulating the gene expression of specific aromatase promoter regions. A possible mechanism for these effects would be the regulation by melatonin of intracellular cAMP levels, mediated by an inhibition of cyclooxygenase activity and expression.     

Experimental cancer cachexia induced by transplantable colon 26 adenocarcinoma in mice

The present study investigates a tumor model for cachectic mice. Among various murine transplantable tumors, used for assessing cytostatics, we identified colon 26 adenocarcinoma (colon 26) as capable of causing cachexia. Fifteen days after inoculation, the tumor grew to about 6% of the body weight causing substantial carcass weight loss of 3.4 g (14.5% of the carcass weight). When the tumor size was 2.7 g at 3 weeks after the inoculation, the carcass weight was 12 g less than the age-matched control. The tumor continued to grow while the mice maintained this weight, surviving for an average of 45 days. This extensive weight loss was essentially the wasting of adipose and muscle tissues. Hypoglycemia and hypercorticism occurred during the time of the weight loss. In addition, the colon 26 caused disorders of hepatic functions: the concentration of acute phase proteins in serum increased; the number of hepatic glucocorticoid-cytosol receptors decreased; and activities of hepatic catalase and drug-metabolizing enzymes decreased. On the other hand, noncachectic mice with Meth A fibrosarcoma gained weight, which was somewhat less than the control, and had neither hypoglycemia nor hypercorticism, although some mild disorders of hepatic functions were found. Mice bearing colon 26 is an appropriate model for elucidating the mechanism that causes cachexia.     

肿瘤坏死因子抗体和高聚金葡素对抗癌症恶病质的初步探讨

目的利用荷瘤动物模型初步探讨癌症恶病质发生机理，评估肿瘤坏死因子抗体（ＴＮＦ－αＡＢ）及高聚金葡素（ＢＭ８２８）治疗恶病质的疗效。方法建立Ｔ７３９／ＬＡ７９５荷瘤小鼠恶病质模型，同时另组小鼠用ＴＮＦ－α作诱导。用放射免疫分析方法测定各组小鼠血清ＴＮＦ－α水平。用ＴＮＦ－αＡＢ和ＢＭ８２８治疗恶病质小鼠，观察各组小鼠摄食量及体重的变化。结果小鼠荷瘤２周后其体重及摄食量明显下降，该组小鼠血清ＴＮＦ－α水平显著高于非荷瘤组；ＴＮＦ－α能诱导小鼠出现类似恶病质的表现。结论ＴＮＦ－α可能是癌症恶病质发生的主要细胞因子之一。ＴＮＦ－αＡＢ及ＢＭ８２８在一定程度上能缓减恶病质发展。     

塞来昔布和谷氨酰胺保护癌性恶病质肠粘膜屏障机制探讨

目的探讨塞来昔布和谷氨酰胺保护癌性恶病质小鼠肠粘膜的机制。方法 28只恶病质小鼠模型随机分为四组:荷瘤组、塞来昔布、谷氨酰胺组和塞来昔布联合谷氨酰胺组。评价塞来昔布和谷氨酰胺对恶病质鼠体重变化和小肠粘膜萎缩以及血清和小肠组织炎性细胞因子表达的影响。结果 塞来昔布和谷氨酰胺均具有抑制恶病质鼠体重下降,保护小肠绒毛,抑制血清中TNFα和IL-6升高、增加sTNFRⅠ、IL-10分泌的作用。二者联用能够升高小肠组织中IFN-γ。结论 塞来昔布和谷氨酰胺通过调节血清和小肠组织中的炎性反应因子保护肠粘膜,缓解体重下降。     

癌性恶病质相关因子及EPA在癌性恶病质中的作用

癌症引起的恶病质即癌性恶病质(CC)是导致癌症患者死亡的主要原因,其致死率高达80%,但至今其发生机制尚不明确,更无有效手段逆转或控制其发展。二十碳五烯酸(EPA)能够促进瘦肌群的合成,因此有望成为治疗CC的主要药物。本文就CC相关的细胞因子、蛋白诱导分解因子、脂肪诱导因子等在CC发生中的作用作一综述,并探讨EPA逆转癌性恶病质的可行性。     

Nitrogen excretion in cancer cachexia and its modification by a high fat diet in mice

Animals transplanted with the MAC16 colon adenocarcinoma showed a loss of body weight as the tumor weight increased, without a reduction in food intake. Both adipose tissue and muscle mass decreased in tumor-bearing animals, although loss of body fat exceeded that of muscle mass for given tumor weight. Urinary nitrogen excretion was significantly elevated when the weight loss did not exceed 3 to 4 g, but above this weight loss there was a conservation of nitrogen and the excretion level fell to or below that found in non-tumor-bearing animals. The presence of a tumor alone was not sufficient to account for the elevated nitrogen excretion, since animals bearing a related colon adenocarcinoma (MAC13) that did not induce weight loss had a nitrogen excretion pattern similar to that of non-tumor-bearing controls. Feeding an isocaloric isonitrogenous diet in which 80% of the calories were supplied as medium chain triglycerides, which significantly elevated plasma levels of ketone bodies, reduced both tumor weight and host weight loss and restored both the nitrogen balance and urea excretion to that of non-tumor-bearing animals. The plasma levels of amino acids, which were reduced in the cachectic state, were also restored to control values in animals fed the medium chain triglyceride diet. These results suggest that excessive nitrogen catabolism in the cachectic state can be prevented by suitable dietary modification.     

Protein metabolism in the small intestine during cancer cachexia and chemotherapy in mice

The impact of cancer cachexia and chemotherapy on small intestinal protein metabolism and its subsequent recovery was investigated. Cancer cachexia was induced in mice with colon 26 adenocarcinoma, which is a small and slow-growing tumor characteristic of the human condition, and can be cured with 100% efficacy using an experimental nitrosourea, cystemustine (C6H12ClN3O4S). Both healthy mice and tumor-bearing mice were given a single i.p. injection of cystemustine (20 mg/kg) 3 days after the onset of cachexia. Cancer cachexia led to a reduced in vivo rate of protein synthesis in the small intestine relative to healthy mice (-13 to -34%; P < 0.05), resulting in a 25% loss of protein mass (P < 0.05), and decreased villus width and crypt depth (P < 0.05). In treated mice, acute cytotoxicity of chemotherapy did not promote further wasting of small intestinal protein mass, nor did it result in further damage to intestinal morphology. In contrast, mucosal damage and a 17% reduction in small intestinal protein mass (P < 0.05) were evident in healthy mice treated with cystemustine, suggesting that the effects of chemotherapy on the small intestine in a state of cancer cachexia are not additive, which was an unexpected finding. Complete and rapid recovery of small intestinal protein mass in cured mice resulted from an increase in the rate of protein synthesis compared with healthy mice (23-34%; P < 0.05). Northern hybridizations of mRNA encoding components of the major proteolytic systems suggested that proteolysis may not have mediated intestinal wasting or recovery. A major clinical goal should be to design methods to improve small intestinal protein metabolism before the initiation of chemotherapy.     

氧化苦参碱通过调节肠道菌群抑制小鼠结直肠癌的相关研究

目的:探讨氧化苦参碱对结直肠癌小鼠肠道菌群的影响及其对小鼠结直肠癌作用的相关微生物机制。方法:将16只5周龄BALB/c雄性小鼠通过氧化偶氮甲烷（AOM）-葡聚糖硫酸钠（DSS）法建立小鼠原位结直肠肿瘤模型,采用分层抽样的方法分为对照组和氧化苦参碱干预组,每组8只;其中氧化苦参碱干预组于造模第5周开始接受10 mg/k...     

Treatment of cancer cachexia in mice by combination of dsRNA-dependent protein kinase inhibitor and medroxyprogesterone acetate

Inhibitor of dsRNA-dependent protein kinase (PKRI) and medroxyprogesterone acetate (MPA) improve cancer cachexia via different mechanisms. We aimed to compare these two drugs, alone or in combination, in cancer cachexia in mice. Forty male BABL/c mice aged 6-8 weeks were randomly divided into PKRI, MPA, PKRI+MPA, placebo, and healthy control groups. The first 4 groups were injected with colon-26 adenocarcinoma and fed for 12 days and then treated with PKRI and MPA alone or in combination for 7 days. Body weight, tumor volume, wet weight of gastrocnemius muscle, serum levels of nutritional markers and cytokines were measured. The tumor growth (volume and weight) of mice treated with PKRI, MPA alone or PKRI+MPA was slower than that of placebo group. Wet weight of gastrocnemius muscle was significantly higher in PKRI and PKRI+MPA-treated than in placebo animals (P<0.01). All tumor-bearing mice had a significantly lower level of blood glucose, higher level of serum triglyceride and lower level of serum albumin compared with healthy control (P<0.001). However, PKRI, MPA and PKRI+MPA groups had a significant higher level of blood glucose and lower level of serum triglyceride compared with placebo group (P<0.001). All tumor bearing mice had a significant higher level of serum TNF-α, IL-1 and IL-6 compared with healthy control (P<0.001). Serum level of TNF-α and IL-6 was significantly lower in PKRI and PKRI+MPA-treated than in placebo animals (P<0.01). PKRI alone and combination therapy with PKRI and MPA reduce tumor growth and may alleviate cachexia.     

Adipose tissue lipolysis and energy metabolism in early cancer cachexia in mice

Cancer cachexia is a progressive metabolic disorder that results in depletion of adipose tissue and skeletal muscle. A growing body of literature suggests that maintaining adipose tissue mass in cachexia may improve quality-of-life and survival outcomes. Studies of lipid metabolism in cachexia, however, have generally focused on later stages of the disorder when severe loss of adipose tissue has already occurred. Here, we investigated lipid metabolism in adipose, liver and muscle tissues during early stage cachexia – before severe fat loss – in the colon-26 murine model of cachexia. White adipose tissue mass in cachectic mice was moderately reduced (34–42%) and weight loss was less than 10% of initial body weight in this study of early cachexia. In white adipose depots of cachectic mice, we found evidence of enhanced protein kinase A - activated lipolysis which coincided with elevated total energy expenditure and increased expression of markers of brown (but not white) adipose tissue thermogenesis and the acute phase response. Total lipids in liver and muscle were unchanged in early cachexia while markers of fatty oxidation were increased. Many of these initial metabolic responses contrast with reports of lipid metabolism in later stages of cachexia. Our observations suggest intervention studies to preserve fat mass in cachexia should be tailored to the stage of cachexia. Our observations also highlight a need for studies that delineate the contribution of cachexia stage and animal model to altered lipid metabolism in cancer cachexia and identify those that most closely mimic the human condition.     

L-carnitine and cancer cachexia. II. Effects of lipid emulsion used in total parenteral nutrition on parameters of hemostasis and inflammatory state in L-carnitine deficiency in myocytes

Cancer cachexia (CC), a progressive loss of body mass, leads to malnutrition and deficiencies of essential substances including polyunsaturated fatty acids (PUFAs) and L-carnitine (LC). The availability of these 2 compounds determines the rate of eicosanoid synthesis, which modulates inflammatory processes and hemostasis. We compared the effects of administration of emulsions containing long chain triglycerides (LCTs) relative to a 50:50 mix of medium chain triglycerides (MCTs) with LCTs on hemostasis and inflammatory reactions in patients with CC. The study was conducted on 50 patients with CC (23 women, 27 men) aged 66 ± 11 years with a mean loss in body weight of 21 ± 9% in the previous 6 months. Twenty patients received MCTs/LCTs while 30 received LCTs. Total parenteral nutrition (TPN) was administered using the 'all in one' method (25 kcal/kg/day, protein 1.2 g/kg/day). Selected parameters of coagulation and inflammatory state were evaluated on days 1, 5, 7 and 11 of TPN. Initial concentrations of D-dimers, fibrinogen, plasminogen activator inhibitor type 1 (PAI-1), fibronectin, CRP and IL-6 significantly exceeded the upper limit of the reference values. After 10 days of TPN, we detected significant differences in inflammatory state and hemostasis. Immunological state and hemostasis varied depending on the type of fat emulsion administered. The most likely reasons are the 2-fold higher concentrations of PUFAs in LCTs relative to MCTs/LCTs and a deficiency of LC in skeletal muscles. Both of these factors may contribute to the observed increase in the rate of eicosanoid synthesis.     

Induction of cachexia in mice by a product isolated from the urine of cachectic cancer patients.

Urine from cancer patients with weight loss showed the presence of an antigen of M(r) 24,000 detected with a monoclonal antibody formed by fusion of splenocytes from mice with cancer cachexia. The antigen was not present in the urine of normal subjects, patients with weight loss from conditions other than cancer or from cancer patients who were weight stable or with low weight loss (1 kg month(-1)). The antigen was present in the urine from subjects with carcinomas of the pancreas, breast, lung and ovary. The antigen was purified from urine using a combination of affinity chromatography with the mouse monoclonal antibody and reversed-phase high-performance liquid chromotography (HPLC). This procedure gave a 200,000-fold purification of the protein over that in the original urine extract and the material isolated was homogeneous, as determined by silver staining of gels. The N-terminal amino acid sequence showed no homology with any of the recognized cytokines. Administration of this material to mice caused a significant (P<0.005) reduction in body weight when compared with a control group receiving material purified in the same way from the urine of a normal subject. Weight loss occurred without a reduction in food and water intake and was prevented by prior administration of the mouse monoclonal antibody. Body composition analysis showed a decrease in both fat and non-fat carcass mass without a change in water content. The effects on body composition were reversed in mice treated with the monoclonal antibody. There was a decrease in protein synthesis and an increase in degradation in skeletal muscle. Protein degradation was associated with an increased prostaglandin E2 (PGE2) release. Both protein degradation and PGE2 release were significantly reduced in mice pretreated with the monoclonal antibody. These results show that the material of M(r) 24,000 present in the urine of cachectic cancer patients is capable of producing a syndrome of cachexia in mice.     

Correlation between enzymatic activity and gene expression of orotate phosphoribosyl transferase (OPRT) in colorectal cancer

BACKGROUND: Orotate phosphoribosyl transferase (OPRT) is the initial key enzyme in the 5-FU metabolic pathway. It is an enzyme that converts 5-fluorouracil into 5-fluorouridine monophosphate. We have previously shown that there is a strong positive correlation between OPRT activity and the antitumor effects of 5-FU. In this study, we investigated the correlation between OPRT activity and mRNA expression levels of OPRT in 10 colorectal tumors. METHODS: Activity was measured by radioassay in tissues. mRNA expression levels (OPRT/beta-actin) were measured by TaqMan PCR assay in the same tissues. RESULTS: There was no correlation between OPRT activity and mRNA expression levels (r = -0.4301, p = 0.8926). DISCUSSION: The absolute amount of an enzyme is determined by speed of synthesis (kappa s) and degradation (kappa deg). OPRT is thought to be a constitutive enzyme, and the results of this study show that it is difficult to estimate the OPRT activity from mRNA expression levels. CONCLUSIONS: Further studies are necessary to develop techniques to measure OPRT activity in biopsies, in order to establish tailor-made therapies based on estimating the antitumor effect of 5-FU from OPRT, an enzyme related to 5-FU metabolism.     

Modulation of adipocyte G-protein expression in cancer cachexia by a lipid-mobilizing factor (LMF)

Adipocytes isolated from cachectic mice bearing the MAC 16 tumour showed over a 3-fold increase in lipolytic response to both low concentrations of isoprenaline and a tumour-derived lipid mobilizing factor (LMF). This was reflected by an enhanced stimulation of adenylate cyclase in plasma membrane fractions of adipocytes in the presence of both factors. There was no up-regulation of adenylate cyclase in response to forskolin, suggesting that the effect arose from a change in receptor number or G-protein expression. Immunoblotting of adipocyte membranes from mice bearing the MAC16 tumour showed an increased expression of Galphas up to 10% weight loss and a reciprocal decrease in Galpha. There was also an increased expression of Galphas and a decrease in Galpha in adipose tissue from a patient with cancer-associated weight loss compared with a non-cachectic cancer patient. The changes in G-protein expression were also seen in adipose tissue of normal mice administered pure LMF as well as in 3T3L1 adipocytes in vitro. The changes in G-protein expression induced by LMF were attenuated by the polyunsaturated fatty acid, eicosapentaenoic acid (EPA). This suggests that this tumour-derived lipolytic factor acts to sensitize adipose tissue to lipolytic stimuli, and that this effect is attenuated by EPA, which is known to preserve adipose tissue in cancer cachexia.     

Amelioration of muscle wasting by gintonin in cancer cachexia

Cancer cachexia is characterized by systemic inflammation, protein degradation, and loss of skeletal muscle. Despite extensive efforts to develop therapeutics, only few effective treatments are available to protect against cancer cachexia. Here, we found that gintonin (GT), a ginseng-derived lysophosphatidic acid receptor (LPAR) ligand, protected C2C12 myotubes from tumor necrosis factor α (TNFα)/interferon γ (IFNγ)- induced muscle wasting condition. The activity of GT was found to be dependent on LPAR/Gαi2, as the LPAR antagonist Ki16425 and Gαi2 siRNA abolished the anti-atrophic effects of GT on myotubes. GT suppressed TNFα-induced oxidative stress by reducing reactive oxygen species and suppressing inflammation-related genes, such as interleukin 6 (IL-6) and NADPH oxidase 2 (NOX-2). In addition, GT exhibited anti-atrophy effects in primary normal human skeletal myoblasts. Further, GT protected against Lewis lung carcinoma cell line (LLC1)-induced cancer cachexia in a mouse model. Specifically, GT rescued the lower levels of grip strength, hanging, and cross-sectional area caused by LLC1. Collectively, our findings suggest that GT may be a good therapeutic candidate for protecting against cancer cachexia.