维生素K3体外降低Ehrlich腹水癌细胞对阿霉素的抗药性

AIM: To study the effect of menadione (Men) reducing doxorubicin (Dox) resistance in Ehrlich ascites carcinoma (EAC) cells resistant to Dox (EAC/Dox cells). METHODS: Glutathione (GSH) content and membrane fluidity were measured by fluorometric assay and fluorescence depolarization assay, respectively. Glutathione S-transferase (GST) activity was measured with 1-chloro-2,4-dinitrobenzene as the substrate. Cell viability was determined by 3-(4, 5-dimethylthiazol)-2, 5-diphenyltetrazolium bromide assay. RESULTS: GSH content, GST activity, and membrane fluidity in EAC/Dox cells were higher than those in EAC cells (P < 0.01). The IC50 (95% confidence limits) for Dox on EAC/Dox cell was 22.3 (15.8-28.8) mg.L-1. Relative resistance of Dox in EAC/Dox cells was 42-fold. Pretreatment of EAC/Dox cells with Men 5 or 10 mg.L-1 decreased intracellular GSH content (P < 0.01). Men 1 mg.L-1 had no obvious effect on GSH content in EAC/Dox cells (P > 0.05), but decreased the elevated membrane fluidity efficiently (P < 0.05). Men had no obvious effect on GST activity in EAC/Dox cells (P > 0.05). IC50 of Dox was reduced to 9.6 (7.8-11.3), 6.0 (2.8-9.2), or 5.3 (3.9-6.7) mg.L-1 in EAC/Dox cells pretreated with Men 1, 5, or 10 mg.L-1. CONCLUSION: Men reduced Dox resistance effectively due in part to its depletion of GSH content in EAC/Dox cells.     

Ehrlich tumor inhibition using doxorubicin containing liposomes

Ehrlich tumors were grown in female balb mice by subcutaneous injection of Ehrlich ascites carcinoma cells. Mice bearing Ehrlich tumor were injected with saline, DOX in solution or DOX encapsulated within liposomes prepared from DMPC/CHOL/DPPG/PEG-PE (100:100:60:4) in molar ratio. Cytotoxicity assay showed that the IC50 of liposomes containing DOX was greater than that DOX only. Tumor growth inhibition curves in terms of mean tumor size (cm³) were presented. All the DOX formulations were effective in preventing tumor growth compared to saline. Treatment with DOX loaded liposomes displayed a pronounced inhibition in tumor growth than treatment with DOX only. Histopathological examination of the entire tumor sections for the various groups revealed marked differences in cellular features accompanied by varying degrees in necrosis percentage ranging from 12% for saline treated mice to 70% for DOX loaded liposome treated mice. The proposed liposomal formulation can efficiently deliver the drug into the tumor cells by endocytosis (or passive diffusion) and lead to a high concentration of DOX in the tumor cells. The study showed that the formulation of liposomal doxorubicin improved the therapeutic index of DOX and had increased anti-tumor activity against Ehrlich tumor models.     

Effect of implanted ethylene-vinyl alcohol copolymer matrices containing 5-fluorouracil on Ehrlich ascites carcinoma

The antitumour activity of ethylene-vinyl alcohol (EVAl) copolymer matrices containing 5-fluorouracil (5-FU) was evaluated against Ehrlich ascites carcinoma in mice. A prolongation of the life-span of tumour-bearing mice following intraperitoneal implantation of therapeutic matrices was noted. These results indicated that EVAl matrices containing 5-FU may be effective in cancer chemotherapy. Matrices composed of EVAl copolymer could be useful vehicles for implanted, inserted, or surface-applied delivery systems for anticancer agents.     

Enhancement of radiation effect by Aphanamixis polystachya in mice transplanted with Ehrlich ascites carcinoma

The effect of radiation on tumor tissue can be optimized by adding radiosensitizing agents, in order to achieve a greater degree of tumor damage than expected from the use of either treatment alone. The ethanolic extract of Aphanamixis polystachya (APE) was tested in Swiss albino mice transplanted with Ehrlich ascites carcinoma (EAC) and exposed to various doses of gamma-radiation. EAC mice received 0, 10, 25, 50, 75, 100, 150 or 200 mg/kg body wt APE before exposure to 6 Gy gamma-radiation followed by once daily administration for another 8 consecutive days post-irradiation. The optimum radiosensitizing dose was found to be 50 mg/kg APE that was further tested in EAC mice exposed to 0, 1, 2, 4, 6 or 8 Gy hemi body gamma-radiation. The best effect of APE and radiation was observed for 6 Gy gamma-radiation. The splitting of 50 mg into two equal fractions of 25 mg and administering the split dose with a gap of 8 h on 1, 3, 5, 7 or 9 d of tumor inoculation resulted in an increased survival even when the drug was administered at late stages (day 5) of tumor development. The APE treatment before irradiation elevated lipid peroxidation followed by a reduction in the glutathione contents. Treatment of tumor bearing mice with APE before irradiation further reduced the activities of various antioxidant enzymes like glutathione peroxidase, glutathione-s-transferase, superoxide dismutase and catalase at different post last drug administration (PLDA) times.     

Antitumoral effect of a selective Rho-kinase inhibitor Y-27632 against Ehrlich ascites carcinoma in mice

BackgroundThe Rho proteins and Rho-kinase (ROCK) enzymes are responsible for signal transduction, and cause cell permeability, contractility, differentiation, migration, proliferation or apoptosis depending on cell types. All of these functions are vital for cancer initiation and progression. In this study, the preventive and protective effects of a selective ROCK inhibitor Y-27632 against Ehrlich ascites carcinoma in Swiss albino mice were investigated.MethodsAdult male albino mice were divided into five equal groups, and Y-27632 (0.1, 1, and 10 mg/kg) was given to groups as two steps; before (pre-carcinoma) and after inoculation of carcinoma cell suspensions (post-carcinoma). At the end of the experiments (at day 15), cardiac blood samples, the ascitic fluid, and intestinal specimens were collected for histopathology and biochemical investigation.ResultsSignificant decreases in the body weight and immunostaining scores in small and large intestine for ROCK2, preservation of serum glutathione (GSH) levels, and an increase in tumor level of nitric oxide were recorded in groups pretreated with Y-27632. However, treatment with Y-27632 after tumor inoculation did not affect body weight and ROCK2 immunostaining scores, increased serum MDA levels, and decreased GSH levels.ConclusionsThis is the first study on the effectiveness of Y-27632 in this experimental tumor model. Our findings provided direct evidence for ROCK involvement in tumor development. These data suggest that pretreatment with Y-27632 has a protective effect against tumor formation.     

Effect of mitoxantrone on DNA polymerase of Ehrlich ascites carcinoma cells.

AIM: To study the effect of mitoxantrone (Mit) on DNA polymerases of tumor cells. METHODS: DNA polymerases of Ehrlich ascites carcinoma cells were isolated by phosphocellulose column chromatography. The effects of Mit on DNA polymerase alpha, beta, and gamma were detected by method of K Ono. RESULTS: Mit inhibited DNA polymerase alpha, beta, and gamma, IC50 values were 11.9, 6.5, and 11.9 mumol.L-1, and Ki 1.86, 2.22, and 2.05 mumol.L-1, respectively. The inhibitory mode of Mit on DNA polymerase alpha, beta, and gamma was competitive. CONCLUSION: Mit is a strong inhibitor on DNA polymerase alpha, beta, and gamma. The inhibitory mode was competition with respect to template DNA.     

Effect of mitoxantrone on DNA polymerase of Ehrlich ascites carcinoma cells

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Enhanced antitumour activity of doxorubicin and simvastatin combination loaded nanoemulsion treatment against a Swiss albino mouse model of Ehrlich ascites carcinoma

Doxorubicin (DOX) is the most commonly used anticancer drug; however, it has limited use because prolonged administration may result in severe cardiotoxicity. Simvastatin (SIM), generally prescribed for hypercholesterolaemia, has also shown salubrious results in the monotherapy or combinational drug therapy of different cancers in various models. Nanoparticle drug delivery systems are a novel way of improving therapeutics and also improving the absorption and specificity of drugs towards tumour cells. In this study, we exploited this technology to increase drug specificity and minimize imminent adverse effects. In this study, the antitumour activity of the combination formulas of DOX and SIM, either loaded in water (DOX‐SIM‐Solution) or nanoemulsions (NEs) (DOX‐SIM‐NE), was evaluated in a Swiss albino mouse model of Ehrlich ascites carcinoma. The anticancer effect was assessed by quantifying the change in body weight, mean survival time, and percent increase in lifespan (%ILS), determining haematological and serum biochemical parameters (liver function test, kidney function test and lipid profile parameters) as well as studying the histopathological alterations in liver tissues. We observed a clear increase in %ILS of the DOX‐SIM‐Solution group (265.30) that was double the %ILS of the DOX‐SIM‐NE group (134.70). However, DOX‐SIM‐NE had a non‐toxic effect on the haematological parameters, whereas DOX‐SIM‐Solution increased the levels of haemoglobin and lymphocytes. Furthermore, the encapsulation of SIM and DOX into NEs improved the levels of all serum biochemical parameters compared to the DOX‐SIM‐Solution. A reduction in the side effects of DOX‐SIM‐NE on the liver was also established using light microscopy, which revealed that the morphologies of the hepatocytes of the mice were less affected by administration of the DOX‐SIM‐NE treatment than with the DOX‐SIM‐Solution treatment. The study showed that incorporating SIM into the DOX‐loaded‐NE formulation remarkably improved its efficiency and simultaneously reduced its adverse effects.     

Altered thymidylate synthetase in 5-fluorodeoxyuridine-resistant Ehrlich ascites carcinoma cells

Thymidylate synthetase from 5-fluorodeoxyuridine-resistant Ehrlich ascites carcinoma cells was purified to a state close to electrophoretical homogeneity (sp. act. = 1.3 mumoles/min/mg protein) and studied in parallel with the homogeneous preparation of the enzyme from the parental Ehrlich ascites carcinoma cells. The enzyme from the resistant cells compared to that from the parental cells showed: (i) a higher turnover number (at least 91 against 31 min-1), (ii) a higher inhibition constant (19 against 1.9 nM) for FdUMP (a tight-binding inhibitor of both enzymes), (iii) a lower activation energy at temps above 36 degrees (1.37 against 2.59 kcal/mole), and (iv) a lower inhibition constant (26 against 108 microM) for dTMP, inhibiting both enzymes competitively vs dUMP.     

Synthesis and retention of methotrexate polyglutamates in Ehrlich ascites carcinoma cells

The formation of methotrexate (MTX) polyglutamates in Ehrlich ascites carcinoma parental and 5-fluorodeoxy-uridine (FdUrd)-resistant cells was examined. The prolonged retention of methotrexate in noneffluxable-polyglutamate form and the pharmacological application of this process is discussed.     

阿霉素对艾氏腹水癌细胞产生多药抗药性的研究

用对阿霉素较为敏感的艾氏腹水癌在小鼠体内用阿霉素进行长达50 wk的治疗,致使EAC细胞对阿霉素产生抗药性.抗药性细胞的生长比敏感株缓慢,每只小鼠体内总的瘤细胞体积,细胞计数,及平均单一细胞体积均比敏感株明显为小,同时还发现染色体匀染及双微体结构.该模型对长春新碱,放线菌素D.及丝裂霉素C均产生交叉抗药性,对VP-16产生部分交叉抗药性.而对冬凌草甲素则无交叉抗药性.     

Antitumor activity of Sansevieria roxburghiana rhizome against Ehrlich ascites carcinoma in mice

Context: Sansevieria roxburghiana Schult. & Schult. f. (Agavaceae) is a herbaceous perennial plant traditionally used for coughs, rheumatism; as an expectorant, febrifuge, purgative, and tonic.

Objective: To evaluate the hydroalcoholic extract of S. roxburghiana rhizome (HASR) for antitumor activity against Ehrlich ascites carcinoma (EAC) in Swiss albino mice.

Methods: Twenty-Four hours after intraperitoneal inoculation of tumor (EAC) cells in mice, HASR was administered at 50 and 100?mg/kg body weight for nine consecutive days. On day 10 half of the mice were sacrificed and rest were kept alive for assessment of increase in life-span. The antitumor effect of HASR was assessed by evaluating tumor volume, packed cell count, viable and non-viable tumor cell count, median survival time and increase in life-span of EAC bearing hosts. Hematological profiles and serum biochemical parameters were estimated. Further, antioxidant properties were assessed by estimating lipid peroxidation, reduced glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT).

Results and discussion: HASR showed a significant (p < 0.001) decrease in tumor volume, packed cell volume and viable cell count and increased the life span of EAC bearing mice. Hematological and serum biochemical profiles were restored to normal levels in HASR treated mice as compared to EAC control. HASR treatment significantly (p <0.001) decreased lipid peroxidation and recovered GSH, SOD and CAT towards normal as compared to EAC control.

Conclusion: The present study demonstrates that S. roxburghiana rhizome exhibited remarkable antitumor activity in Swiss mice that is plausibly attributable to its augmenting endogenous antioxidant mechanisms.     

Antitumour Activity of Mitoxantrone-loaded Chitosan Microspheres Against Ehrlich Ascites Carcinoma

Glutaraldehyde cross-linked chitosan microspheres containing the antineoplastic agent mitoxantrone were prepared and the antitumour activity was evaluated against Ehrlich ascites carcinoma in mice by intraperitoneal injections. The tumour inhibitory effect was followed by monitoring animal survival time and change in body weight for a period of 60 days. While the mean survival time of animals which received 2 mg and 1 mg of free mitoxantrone intraperi-toneally was 2.1 and 4.6 days, respectively, animals which received 2 mg mitoxantrone via microspheres showed a mean survival time of 50 days. Five out of 8 animals treated using microspheres lived beyond 60 days. The percentage ratio mean survival time of the treated group divided by the mean survival time of the untreated group for animals treated using mitoxantrone-loaded chitosan microspheres containing 2 mg of the drug was 290 compared with 12.2 for those which received 2 mg of the free drug. The antitumour effect of mitoxantrone-loaded microspheres against Ehrlich ascites carcinoma was much higher than that of doxorubicin-loaded microspheres reported by previous workers. Our data demonstrate the potential of mitoxantrone-loaded chitosan microspheres for sustained drug delivery to minimize drug toxicity and maximize therapeutic efficacy.     

The effect of levamisole on energy metabolism in Ehrlich ascites tumour cells in vitro

It has been found that levamisole, an anthelmintic drug, used also as an immunomodulator in human cancer therapy, is a strong inhibitor of tumour aerobic glycolysis. In vitro, in Ehrlich ascites tumour (EAT) cells and supernatants it diminishes glucose uptake and lactate formation. It does not, however, exert a similar inhibitory effect on glycolytic activity in normal liver and muscle supernatants. Metabolic and enzymatic studies have shown that levamisole directly inhibits tumour phosphofructokinase decreasing ATP, as well as 2-phosphoenolpyruvate and pyruvate as further glycolytic intermediates. L-Cysteine used for comparison also as another inhibitor of tumour aerobic glycolysis, decreasing glucose uptake and lactate formation and diminishing pyruvate and ATP levels, differs in the accompanying increase in 2-phosphoenolpyruvate concentration. This crossing-over in metabolite concentration, only seen in tumour material, points to tumour pyruvate kinase as an isoenzyme sensitive to cysteine inhibition. Direct enzymatic studies have confirmed this suggestion. Some similarities in the influence on the metabolism of both compounds studied have been discussed, as well as the role of the effects observed in understanding the mechanisms of levamisole action (also in worms).