Walker-256 Tumor: Experimental Model, Implantation Sites and Number of Cells for Ascitic and Solid Tumor Development

Abstract The Walker-256 tumor is an important experimental model that allow the development of therapies as the biological behavior of this tumor is similar that occur in humans. In front of the above considerations, the aim of this study was to describe the experimental model of Walker-256 tumor, identify the implantations sites as well as define a usual quantity of tumoral cells to induce the ascitic and solid tumor, according to the specialized literature. Were selected 45 articles using the keyword "Walker-256 tumor", free available. Were possible to observe that 58% (n=26) of the studies inoculate the tumor cells in the animals flank 33% (n = 15) in the tibia bone, 7% (n = 3) in the femur and 2% (n = 1) in the paw. The major quantitates of cells used were 8 x 107 (20%), 1 x 105 (13%), 1 x 106 (11%) and 2 x 107 (11%). After that, the site commonly used to inoculate was the flank and quantitate still a controversy, being 1x105 and 8x107 the concentrations more used.

Growth inhibition of Walker carcinosarcoma 256 with alcoholic extract of green tea leaves (Camellia sinensis).

PURPOSE: To evaluate the antitumor activity of alcoholic extracts of green tea (Camella sinensis). METHODS: Four groups of six Wistar rats were inoculated intramuscularly with 10(6) Walker tumor cells/mL. During 10 days, the animals received by gavage either 0.9% saline solution (Group I; negative control), solution containing 20 mg/Kg of tamoxifen (Group II; positive control), solution containing 0.07 g/Kg alcoholic extract of C. sinensis (Group III), or solution containing 0.14 g/Kg alcoholic extract of C. sinensis (Group IV). Following euthanasia on the tenth day, the tumor, liver, kidneys and spleen were excised and weighed, and tumor volume and tumor growth inhibition were quantified. RESULTS: The average weight of the animals was greater in Group IV than in Group II (p=0.0107). Tumor weight was smaller in Group IV than in Group I (p=0.0062), but did not differ from Group II. Tumor volume was smaller in Groups II and IV than in Group I (p=0.0131). Tumor growth inhibition was observed in Groups II (44.67% ± 32.47), III (16.83% ± 53.02) and IV (66.4% ± 25.82) (p>0.05). The groups did not differ with regard to the weight of the excised organs. CONCLUSION: Alcoholic extracts of green tea have antitumor activity.

The hemolytic component of cancer anemia: effects of osmotic and metabolic stress on the erythrocytes of rats bearing multifocal inoculations of the Walker 256 tumor.

Cancer anemia is classified as an anemia of chronic diseases, although it is sometimes the first symptom of cancer. Cancer anemia includes a hemolytic component, important in the terminal stage when even transfused cells are rapidly destroyed. The presence of a chronic component and the terminal complications of the illness limit studies of the hemolytic component. A multifocal model of tumor growth was used here to simulate the terminal metastatic dissemination stage (several simultaneous inoculations of Walker 256 cells). The hemolytic component of anemia began 3-4 days after inoculation in 100% of the rats and progressed rapidly thereafter: Hb levels dropped from 14.9 +/- 0.02 to 8.7 +/- 0.06 from days 7 to 11 ( approximately 5 times the physiologically normal rate in rats) in the absence of bleeding. The development of anemia was correlated (r2 = 0.86) with the development of other systemic effects such as anorexia. There was a significant decrease in the osmotic fragility of circulating erythrocytes: the NaCl concentration causing 50% lysis was reduced from 4.52 +/- 0.06 to 4.10 +/- 0.01 (P<0.01) on day 7, indicating a reduction in erythrocyte volume. However, with mild metabolic stress (4-h incubation at 37oC), the erythrocytes showed a greater increase in osmotic fragility than the controls, suggesting marked alteration of erythrocyte homeostasis. These effects may be due to primary plasma membrane alterations (transport and/or permeability) and/or may be secondary to metabolic changes. This multifocal model is adequate for studying the hemolytic component of cancer anemia since it is rapid, highly reproducible and causes minimal animal suffering.

The hemolytic component of cancer anemia: effects of osmotic and metabolic stress on the erythrocytes of rats bearing multifocal inoculations of the Walker 256 tumor

Cancer anemia is classified as an anemia of chronic diseases, although it is sometimes the first symptom of cancer. Cancer anemia includes a hemolytic component, important in the terminal stage when even transfused cells are rapidly destroyed. The presence of a chronic component and the terminal complications of the illness limit studies of the hemolytic component. A multifocal model of tumor growth was used here to simulate the terminal metastatic dissemination stage (several simultaneous inoculations of Walker 256 cells). The hemolytic component of anemia began 3-4 days after inoculation in 100 percent of the rats and progressed rapidly thereafter: Hb levels dropped from 14.9 +/- 0.02 to 8.7 +/- 0.06 from days 7 to 11 (~5 times the physiologically normal rate in rats) in the absence of bleeding. The development of anemia was correlated (r2 = 0.86) with the development of other systemic effects such as anorexia. There was a significant decrease in the osmotic fragility of circulating erythrocytes: the NaCl concentration causing 50 percent lysis was reduced from 4.52 +/- 0.06 to 4.10 +/- 0.01 (P<0.01) on day 7, indicating a reduction in erythrocyte volume. However, with mild metabolic stress (4-h incubation at 37§C), the erythrocytes showed a greater increase in osmotic fragility than the controls, suggesting marked alteration of erythrocyte homeostasis. These effects may be due to primary plasma membrane alterations (transport and/or permeability) and/or may be secondary to metabolic changes. This multifocal model is adequate for studying the hemolytic component of cancer anemia since it is rapid, highly reproducible and causes minimal animal suffering.

Efeitos biológicos dos hormônios tireoideanos em ratos portadores de tumor de Walker / Biological effects of the thyroid hormones in Walker tumor-bearing rats

Ratos receberam implante de células tumorais (Walker 256) sendo sacrificados 7-21 dias mais tarde. Nesses animais verificou-se queda substancial dos níveis circulantes de T3 e T4 (15-60 por cento) e aumento dos de rT3 (1-3,7 vezes), caracterizando a síndrome do T3 baixo. Estas alteraçöes apresentaram alta correlaçäo estatística com o peso do tumor (1,2-25g; p<05 para T4, T3 e rT3) e em menor grau com o tempo de evoluçäo do tumor (7-21 dias; p<0,05 para T4 e T3). A atividade das enzimas lipogênicas, málica (EM) e glicose-6-fosfato desidrogenase (G-6P-D), no fígado e coraçäo desses animais apresentou diminuiçäo que beirou o limite da significância estatística [EM(17-29 por cento) e G-6-33)], dependendo do tempo de evoluçäo e do tecido estudado. Nesses mesmos animais, a atividade da enzima mitocondrial oxidativa alfa-glicerolfosfato desidrogenase (alfa-GPD), entretanto, apresentou diminuiçäo bastante maior (27-53 por cento) e sempre estatisticamente significativa. A injeçäo de dose saturante de T3 (100µg/100g de peso corporal, i.p.) em ratos portadores de tumor de Walker, 24h antes do scrifício, resultou em estimulaçäo das enzimas EM (1,7-3,3 vezes) e G-6P-D(33-150 por cento), maior que a observada nos respectivos animais controle. Entretanto, a induçäo na atividade da alfa-GPD mitocondrial causada pelo T3, embora, näo foi maior que a observada nos animais controle. Finalmente, a infusäo de doses fisológicas de T3(300ng/100g de peso corporal/dia), por 5 dias, através do implante subcurâneo de mini-bomba osmótica em ratos portadores de tumor, resultou em normalizaçäo da EM e G-6P-D em ambos os tecidos e num aumento significativo de alfa-GPD mitocondrial, embora näo suficiente para atingir a normalizaçäo. Esses resultados indicam que, ao contrário do que se poderia esperar, enzimas envolvidas em diferentes vias metabólicas (lipogênese e fosforilaçäo oxidativa) respondem de forma diferente às alteraçöes desencadeadas na síndrome do T3 baixo e a administraçäo de T3, sugerindo a existência de diferentes mecanismos adaptativos desencadeados nos tecidos alvo dos hormônios tireoideanos durante a instalaçäo dessa sídrome

Modificaçäo da resposta cutânea ao teste de hipersensibilidade tardia em desnutriçäo e câncer: estudo experimental / Skin response in delayed hypersensibilitty in malnutrition and cancer: experimental study

O tumor maligno é capaz de interferir com os valores do peso da carcaça, da albumina sérica e dos testes de hipersensibilidade, o mesmo acontecendo com a desnutriçäo. Procurando distinguir os efeitos dos dois fenômenos, ratos Wistar adultos foram submetidos a diferentes manipulaçöes nutricionais em associaçäo com o implante de células de carcinomassarcoma de Walker 256 (TU). Seis grupos de animais normais com resposta positiva ao Keyhole Limpet hemocyanin (KLH) foram estudados. Três grupos de ratos portadores de tumor foram submetidos a diferentes esquemas nutricionais: dieta aprotéica antes e depois do implante tumoral (grupo DDT); dieta aprotéica antes do implante, seguindo-se dieta normal (grupo DNT); dieta normal ao longo de todo o experimento (grupo NNT). Grupos controles sem tumor receberam os mesmos tratamentos nutricionais, constituindo os grupos DDC, DNC e NNC. O peso corpóreo dos ratos e da massa tumoral em evoluçäo foram determinados diariamente; os testes KLH foram realizados periodicamente e a albumina sérica foi dosada no dia do sacrifício dos animais. Os resultados indicam que o tumor maligno produz acentuadas modificaçöes na resposta imunológica; a desnutriçäo é responsável por anergia e perda de peso . Quando ambas as condiçöes estäo presentes, ocorrem pertubaçöes mais acentuadas. A realimentaçäo (grupos DNC e DNT) foi capaz de restabelecer o peso corpóreo e a resposta ao KLK, tanto nos ratos normais, quanto nos portadores de tumor, mas prejuízo subseqüente ocorreu em ratos portadores do tumor, depois da primeira semana de desenvolvimento tumoral. Conclui-se que o câncer potencializa os efeitos da desnutriçäo sobre o peso corpóreo e a resposta imunológica, com recuperaçäo temporária após adequada realimentaçäo

[Influence of methylcobalamin and cyanocobalamin on the neoplastic process in rats].

The effect of methylcobalamine (5.6-dimethylbenzimidazolyl-Co-methylcobamide, CH3-B12) and cyanocobalamine (5,6-dimethylbenzimidazolyly-Co-cyanocobamide, CN-B12) on the growth of Walker's carcinosarcoma and longevity of white noninbred rats with implanted Zajdela ascites hepatoma was studied. The two agents exerted a similar effect. They 1) reduced the survival of rats with implanted Zajdela ascites hepatoma and Walker's carcinosarcoma; 2) did not increase the cell concentration in ascites; and 3) increased the total volume of ascites.

Circadian variations in 32P uptake of DMBA-induced mammary tumour and Walker carcinosarcoma in rats.

The 32P uptake in a mammary tumour induced by DMBA and in the Walker 256 carcinosarcoma was measured by external GM -tubes. The uptake was significantly higher than in the skin. During exposure to a synchronized light regime a circadian variation was present in the 32P uptake of the hormone-dependent DMBA-induced tumour. The maximal 32P uptake was in the dark period, in which the highest temperature in the tumour has also been found (Møoller and Bojsen, 1975). In the hormone-independent Walker 256 carcinosarcoma there was no periodicity in 32P uptake. No variation in 32P uptake was registered in the skin of normal controls or in tumour-bearing rats.