Altered tryptophan metabolism in human meningioma

Meningiomas are the neoplasms that arise from the arachnoid cells of the meninges. It was reported that cancer cells escape from immune system through the metabolism of an aromatic essential amino acid tryptophan (TRP) via Kynurenine (KYN) pathway. However, the role of TRP metabolites such as, 5-Hydroxy tryptophan (5-HTP), 5-Hydroxy tryptamine (5-HT), N-acetyl serotonin (NAS), Melatonin (MEL), KYN, N-acetyl tryptamine, 5-Hydroxy indole acetic acid (5-HIAA) and 5-Methoxy indole acetic acid is not yet evaluated in human meningioma. Therefore, in the current study we have evaluated the levels of TRP and its metabolites in the progression of human meningioma using tumor biopsy samples and autopsy control meninges with Reverse Phase-HPLC. We here report that TRP metabolism favors towards KYN pathway in human meningioma and it could be due to increased indoleamine 2,3-dioxygenase 2 levels as we found its m-RNA levels to be up regulated in human meningioma. We observed significant increase in KYN and 5HIAA levels and significant decrease in TRP, 5-HTP, 5-HT, NAS and MEL levels in meningioma compared to control meninges. Since TRP metabolites regulate inducible nitric oxide synthase (INOS) gene expression and thereby nitric oxide (NO) production, we have also evaluated the INOS and NO levels. The INOS and NO levels were up regulated in human meningioma. The present data corroborates with existing data on TRP metabolism in tumor progression and may serve to target TRP metabolism as a therapeutic intervention.     

Interaction of liposome-associated all-trans-retinoic acid with squamous carcinoma cells

Summary Because of their antiproliferative and differentiation-inducing properties, retinoids have been used clinically as therapeutic and chemopreventive agents against squamous-cell carcinomas (SCC). As is the case for many therapeutic agents, however, the administration of retinoids is associated with toxic effects. Because encapsulation of certain drugs in lipid vesicles (liposomes) has been shown to result in reduced toxic effects, we studied the in vitro interaction of liposome-encapsulated all-trans-retinoic acid (L-ATRA) with a SCC line (MDA 886Ln) and its multicellular tumor spheroid (MTS) model. Various L-ATRA formulations were tested for incorporation of retinoic acid, toxic effects against human red blood cells, uptake and retention by tumor cells, and anti-proliferative effects against SCC. Of the different formulations tested, L-ATRA containing diphosphatidyl palmitoylcholine (DPPC) and stearylamine (SA; 9:1, w/w) showed optimal drug incorporation, high stability, and minimal toxicity toward red blood cells and was highly efficacious in delivering ATRA and, thus, in inhibiting the growth of MDA 886Ln and its MTS model. DPPC: SA L-ATRA inhibited the expression of the enzyme keratinocyte transglutaminase in epidermal cells as effectively as did the free drug. These results suggest that liposomes can serve as an effective carrier system for the delivery of retinoids to SCC.This work was supported in part by Public Health Service grants FDR000923 from the Orphan Products Division, Food and Drug Administration, and CA 57116 from the National Cancer Institute     

Inhaled aerosolization of all-trans-retinoic acid for targeted pulmonary delivery

Retinoids have shown promising activity for both cancer chemoprevention and as a treatment for emphysema. However, chronic oral administration of these drugs is limited by systemic side effects, including hepatic dysfunction, skeletal malformations, hyperlipidemia, hypercalcemia, and other reactions. In order to improve the pulmonary targeting of this potentially useful therapy, we developed a system for aerosolization of retinoids that substantially increased their local bioavailability. We compared the biodistribution and pharmacokinetics of an inhaled formulation of all-trans-retinoic acid (all-trans-RA), which was packaged in a metered dose inhaler, following both intratracheal (IT) and intravenous (IV) administration in male Sprague-Dawley rats. After drug administration, anesthetized animals were killed at 5 min, and at 1, 2, 4, 6 and 24 h. Plasma and emulsified samples of liver and lung tissues were dissected, extracted, and frozen prior to measurement of all-trans-RA concentration by high-performance liquid chromatography (HPLC). Aerosolization and IT injection of all-trans-RA resulted in a significantly longer pulmonary half-life of the drug (both 5–17 h), lower peak serum concentrations (aerosol 71 ± 31 ng/ml, IT 68 ± 50 ng/ml), and lower liver levels (aerosol 111 ± 28 ng/g, IT 753 ± 350 ng/g) than the same dose administered IV (2 h, 838 ± 56 ng/ml, 4258 ± 1006 ng/g, respectively; P < 0.05 for each comparison). Histologic examination of lungs and trachea showed no focal irritation attributable to the drug after single-dose administration. These results suggest that aerosolization of retinoids may offer a practical alternative to systemic oral administration for chemoprevention trials or treatment of lung diseases. This method may substantially increase the therapeutic index of these compounds by reducing systemic complications associated with long-term dosing. Received: 17 September 1999 / Accepted: 14 April 2000     

Altered regulation of arachidonic acid metabolism by SV40 immortalized human urothelial cells.

Regulation of arachidonic acid metabolism was investigated in an SV40 immortalized, non-tumorigenic human urothelial cell line (SV-HUC). This cell line is being used to evaluate the multistage carcinogenic process. Media from confluent cultures were analyzed for radioimmunoassayable prostaglandin E2 (PGE2). A variety of agonists, including 12-O-tetradecanoylphorbol-13-acetate (TPA) and A23187 were tested and did not increase PGE2 synthesis within 2 h of addition. This was not due to the lack of prostaglandin H synthase activity because addition of exogenous arachidonic acid increased PGE2 synthesis. Cultures prelabeled overnight with [3H]arachidonic acid failed to increase the release of radioactivity following agonist addition. Thus, the lack of an early response in SV-HUC appears to be due to decreased release of endogenous arachidonic acid by phospholipase(s). After a 24 h incubation with 0.1 microM TPA or 1.0 microM A23187, the addition of arachidonic acid elicited significantly more PGE2 synthesis in agonist-treated cells than it did in control cells. Microsomes from 24 h TPA-treated cells produced approximately 15-fold more PGE2 than did those from control cells. In addition, the PGE2 content of overnight media was significantly greater in TPA-treated cells than in control cells. The 24 h agonist response was blocked by cycloheximide and staurosporine--inhibitors of protein synthesis and protein kinase C respectively. Pretreatment of cells with aspirin, an irreversible inhibitor of prostaglandin H synthase, prior to addition of TPA did not prevent the late 24 h TPA-mediated increase in PGE2 synthesis. Results suggest that this late effect of TPA is due to de novo synthesis of prostaglandin H synthase. Thus, SV-HUC has lost the early but retains the late response to agonists.     

Altered glucose metabolism in metastatic carcinoma.

To evaluate the possible role of altered glucose metabolism in malignant cachexia, metabolic parameters including total glucose turnover, glucose oxidation, and Cori cycle activity were measured in fourteen patients with metastatic carcinoma. Eight patients with progressive weight loss (PWL) were compared to 6 without (controls). Cori cycle activity was significantly increased (p less than 0.02) in PWL patients, 90 mg/kg/hr (range, 22 to 193) compared to 18 mg/kg/hr (range, 13 to 24) in controls. Total glucose turnover was moderately increased in PWL patients, 196 mg/kg/hr compared to 110 mg/kg/hr in controls. Glucose oxidation was 62 mg/kg/hr versus 48 mg/kg/hr, and total caloric expenditure was 36 kcal/sq m/hr compared to 33 Kcal/sq m/hr. PWL patients were metabolically heterogenous and mean values are skewed by four patients with increased glucose turnover, oxidation, and markedly high recycling rates that were equivalent to total endogenous glucose turnover of a normal subject. Total caloric expenditure was greatest in three of the four patients with a marked increase in Cori cycle activity. Energy loss associated with a high rate of gluconeogenesis from lactate has been suggested as an explanation for increased energy expenditure in some cancer patients, thus contributing to mechanisms that promote weight loss.     

Altered leucine metabolism in noncachectic sarcoma patients

Leucine and whole body protein metabolism were quantitated in 26 human subjects (6 sarcoma patients, 20 age-matched normal controls) using a primed, continuous infusion of [13C]leucine. Plasma samples were analyzed every 15 min for enrichment of [13C]leucine. Plateau enrichment levels were then used to calculate whole-body protein turnover, synthesis, and breakdown rates. Exhaled gas samples were analyzed every 15 min for enrichment of 13CO2, and plateau enrichment levels (as well as CO2 production rates) were used to calculate leucine oxidation rates. Fasting plasma amino acid levels, serum albumin, and total protein levels were also determined. The 6 patients were otherwise healthy but had a large, localized high-grade sarcoma which had not been previously treated. No patient had weight loss. Amino acid, albumin, and total protein levels were equivalent in patients and controls. Whole-body protein turnover rates were significantly greater in sarcoma patients than age-matched controls (15%). Increased protein turnover rates resulted in increased whole-body protein synthesis and breakdown rates in sarcoma patients compared to controls. Leucine oxidation rates were not different in the 2 groups. The results suggest that in humans with high-grade sarcomas leucine metabolic abnormalities are specific to tumor growth and not malnutrition because abnormalities of turnover, synthesis, and breakdown occur prior to any weight loss or measurable change in blood amino acid or protein level.     

Altered methionine metabolism and transmethylation in cancer

Methionine metabolism and transmethylation are frequently altered in cancer cells. The alteration is often expressed as an inability of the cancer cells to grow when methionine is replaced by homocysteine in the culture medium, a condition that allows the growth of normal cells. This metabolic defect is termed methionine dependence. Methionine dependence may reflect an overall imbalance in transmethylation which results in the overmethylation of some substances and undermethylation of others within cancer cells. Many carcinogens affect various stages of methionine/transmethylation metabolism. The ultimate effect of the alteration of methionine/transmethylation metabolism may be the disruption of the regulation of genes involved in the oncogenic process. The known protective effect of methionine against cancer may be due to prevention of altered methionine/transmethylation metabolism or compensation of the altered metabolism.     

Network-guided modeling allows tumor-type independent prediction of sensitivity to all-trans-retinoic acid

BackgroundAll-trans-retinoic acid (ATRA) is a differentiating agent used in the treatment of acute-promyelocytic-leukemia (APL) and it is under-exploited in other malignancies despite its low systemic toxicity. A rational/personalized use of ATRA requires the development of predictive tools allowing identification of sensitive cancer types and responsive individuals.Materials and methodsRNA-sequencing data for 10 080 patients and 33 different tumor types were derived from the TCGA and Leucegene datasets and completely re-processed. The study was carried out using machine learning methods and network analysis.ResultsWe profiled a large panel of breast-cancer cell-lines forin vitro sensitivity to ATRA and exploited the associated basal gene-expression data to initially generate a model predicting ATRA-sensitivity in this disease. Starting from these results and using a network-guided approach, we developed a generalized model (ATRA-21) whose validity extends to tumor types other than breast cancer.ATRA-21 predictions correlate with experimentally determined sensitivity in a large panel of cell-lines representative of numerous tumor types. In patients,ATRA-21 correctly identifies APL as the most sensitive acute-myelogenous-leukemia subtype and indicates that uveal-melanoma and low-grade glioma are top-ranking diseases as for average predicted responsiveness to ATRA. There is a consistent number of tumor types for which higherATRA-21 predictions are associated with better outcomes.ConclusionsIn summary, we generated a tumor-type independent ATRA-sensitivity predictor which consists of a restricted number of genes and has the potential to be applied in the clinics. Identification of the tumor types that are likely to be generally sensitive to the action of ATRA paves the way to the design of clinical studies in the context of these diseases. In addition,ATRA-21 may represent an important diagnostic tool for the selection of individual patients who may benefit from ATRA-based therapeutic strategies also in tumors characterized by lower average sensitivity.     

Enhancement of murine hepatocarcinogenesis by all-trans-retinoic acid and two synthetic retinamides

Although retinoids have significant chemopreventive activity in many in vivo carcinogenesis models, their influence on experimental hepatocarcinogenesis has received only limited study. The present experiment was designed to determine the effects of three retinoids on hepatocarcinogenesis induced in female B6D2F1 mice by diethylnitrosamine (DEN). Beginning 1 week after a single i.p. dose of 0, 50 or 100 mg DEN per kg body wt, groups of 35 mice received dietary supplements of (per kg diet): 0.1 mmol all-trans-retinoic acid (RA), 0.5 or 1.0 mmol all-trans-ethyl retinamide (ER), 0.5 or 1.0 mmol 13-cis-ethyl retinamide (13-cis-ER), or vehicle only. In mice treated with 100 mg DEN/kg, all three retinoids significantly increased the incidence of liver tumors (benign + malignant) from the level seen in dietary controls; significant increases in the incidence of hepatocellular carcinoma were seen in groups fed ER. At the lower DEN dose, all three retinoids significantly increased the incidence of total liver tumors and of hepatocellular carcinomas. In mice not treated with DEN, liver tumors were seen only in mice fed ER or 13-cis-ER at 1.0 mmol/kg diet. These data indicate that RA, ER and 13-cis-ER can promote liver carcinogenesis in mice when administered at doses that inhibit cancer induction in other tissues. Because chronic exposure to many retinoids results in the deposition and accumulation of both parent compound and metabolites in the liver, these results should suggest caution in the design of clinical chemoprevention trials with this class of compounds.     

The treatment of recurrent cerebral gliomas with all-trans-retinoic acid (tretinoin)

Malignant gliomas continue to be a significant sourceof mortality in young and middle aged adults.The introduction of new treatment strategies and multidisciplinaryapproaches has improved the outcome of patients withthese tumors only slightly. Because retinoic acid hasgrowth inhibitory activity against glioma and neuroblastoma cellsin cultures, we assessed the efficacy of all-trans-retinoicacid in the treatment of recurrent cerebral gliomas.Thirty-six patients with recurrent cerebral gliomas were enteredin the study and treated with 120 or150 mg/m²/day of all-trans-retinoic acid as a singleagent. The drug was given for 3 weeksfollowed with one week of rest. Two blocksof 4 weeks constituted one course of treatment.One (3%) of 34 evaluable patients had aminor response and 14 (41%) had stable disease.In the rest of the patients (56%), tumorscontinued to progress despite treatment. The median timeto progression of all evaluable patients was 8weeks, and for the responders was 17 weeks.The higher dose level (150 mg/m²) was associatedwith high incidence of headache, which responded todose reduction. The lower dose level was verywell tolerated, with mild, mainly dermatological toxicity.All-trans-retinoic acid as a single agent has nosignificant activity against recurrent cerebral gliomas.     

全反式维甲酸联合化疗治疗小儿急性早幼粒细胞白血病

目的观察全反式维甲酸（ATRA）联合化疗治疗小儿急性早幼粒细胞白血病（APL）的疗效。方法22例初治患儿用ATRA诱导治疗;当患儿获完全缓解（CR）后,给予DA方案或IDA方案或HA方案或AA方案巩固治疗3个疗程;以后再用ATRA、化疗交替巩固治疗36个月。结果2例在诱导治疗前死于弥散性血管内凝血（DIC）、颅内出血;22例获CR,CR率100％（20／20）。1、3、5年无病生存（DFS）率分别为100％（20／20）、93．3％（14／15）、84．7％（11／13）。ATRA常见毒副作用依次为皮肤和口唇干燥、头痛、恶心、呕吐、肝功能损害及维甲酸综合征。结论ATRA联合化疗治疗小儿APLCR率高、远期疗效好;在诱导治疗前,DIC、颅内出血仍是APL患儿死亡的主要原因;ATRA毒副作用可耐受。