Expression of the glutamine metabolism-related proteins glutaminase 1 and glutamate dehydrogenase in canine mammary tumours.

Glutamine metabolism is an important metabolic pathway for cancer cell survival, and there is a critical connection between tumour growth and glutamine metabolism. Because of their similarities, canine mammary carcinomas are useful for studying human breast cancer. Accordingly, we investigated the correlations between the expression of glutamine metabolism-related proteins and the pathological features of canine mammary tumours. We performed immunohistochemical and western blot analysis of 39 mammary tumour tissues. In immunohistochemical analysis, the expression of glutaminase 1 (GLS1) in the epithelial region increased according to the histological grade (P < .005). In the stromal region, complex-type tumours displayed significantly higher GLS1 intensity than simple-type tumours. However, glutamate dehydrogenase expression did not show the same tendencies as GLS1. The western blot results were consistent with the immunohistochemical findings. These results suggest that the expression of GLS1 is correlates with clinicopathological factors in canine mammary tumours and shows a similar pattern to human breast cancer.

Electroporation markedly improves Sleeping Beauty transposon-induced tumorigenesis in mice.

The Sleeping Beauty (SB) transposon system is an important tool for genetic studies. It is used to insert a gene of interest into the host chromosome, thus enabling permanent gene expression. However, this system is less useful in higher eukaryotes because the transposition frequency is low. Efforts to improve the efficacy of the SB transposon system have focused on the method of gene delivery, but although electroporation has recently attracted much attention as an in vivo gene delivery tool, the simultaneous use of electroporation and the SB transposon system has not been studied for gene transfer in mice. In this study, electroporation was used in a model of SB transposon-induced insertional tumorigenesis. Electroporation increased the rate of tumor development to three times that of the control group. There was no difference in phenotype between tumors induced with the SB transposon system alone and those induced by the SB transposon and electroporation. Electroporation therefore may be an efficient means of improving the efficacy of gene transfer via the SB transposon system.

Subacute toxicity evaluation of a new camptothecin anticancer agent CKD-602 administered by intravenous injection to rats.

The subacute toxicity of a new camptothecin anticancer agent, CKD-602, was investigated after 4-week repeated intravenous administration of the chemical in Sprague-Dawley rats. The test chemical was administered intravenously to rats at dose levels of 0, 0.003, 0.013, or 0.067 mg/kg/day for males and 0, 0.004, 0.018, or 0.089 mg/kg/day for females. At the end of the treatment period, 10 rats/sex/group were sacrificed. The remaining 5 rats/sex in the vehicle control and high dose groups continued the study without treatment for 2 weeks (recovery period). During the test period, clinical signs, mortality, body weights, food and water consumption, ophthalmoscopy, urinalysis, hematology, serum biochemistry, gross findings, organ weights, and histopathology were examined. In both sexes of the high dose group, an increase in the incidence of abnormal clinical signs and paleness of the eyes, a reduction in the body weight gain, food consumption and urine protein, and an increase in the water consumption were observed. Hematological investigations revealed a decrease in the red blood cells, hemoglobin and hematocrit and an increase in the mean corpuscular volume, mean corpuscular hemoglobin, platelets, and reticulocytes in a dose-dependent manner. Serum total cholesterol and total protein values were lower in females than those of controls, but not in males. An increase in the heart and liver weights and a decrease in the thymus weight were also found. Histopathological alterations included an increase in the incidence of atrophy of the sternal marrow, atrophy, fibrosis and mast cell hyperplasia of the femoral marrow, atrophy of the white pulp and extramedullary hematopoiesis of the spleen, atrophy of the thymus, auricular hypertrophy of the heart, extramedullary hematopoiesis and centriacinar telangiectasis of the liver, follicular degeneration of the ovary, and inflammation of the tail. The major treatment-related effects were not recovered at the end of 2-week recovery period. There were no adverse effects in the low and middle dose groups of both genders. In the present experimental conditions, the target organs were determined to be bone marrow, blood cells, spleen, liver, thymus, and heart. The no-observed-adverse-effect level was considered to be 0.013 mg/kg/day for males and 0.018 mg/kg/day for females.

Sex differences in dizocilpine (MK-801) neurotoxicity in rats.

The sex differences in the clinical signs and the distribution of astrocytic glial fibrillary acidic protein (GFAP) induced by an N-methyl-d-aspartate antagonist, dizocilpine (MK-801), were examined. A single intraperitoneal injection of MK-801 (5 mg/kg body weight) caused a prolonged recumbency (35-40 h), leading to a severe loss of body weight in female rats, in contrast to a light effect in males, independent of age. Early salivation or lacrimation was also severe in females and delayed bloody lacrimation was observed in females only. The pretreatment with 17ß-estradiol (0.1 or 1.0 mg/kg body weight) made early signs worse in both sexes, but a remarkable mortality (20-40%) was observed in females only. The treatment with MK-801 greatly enhanced GFAP expression in retrospenial cortex of both sexes with a higher enhancement in females. The MK-801-induced expression of GFAP was further increased by the pretreatment with 17ß-estradiol (1 mg/kg body weight) in females. Overall, the expression of GFAP in the retrospenial cortex of rats treated with MK-801 appeared to be higher in females than males, somewhat in parallel with more severe clinical signs in females. The results indicate the higher sensitivity of female rats to MK-801 neurotixicity, and the possible involvement of 17ß-estradiol in the sex differences of the sensitivity.

Lack of influence of diethylstilbestrol on induced pancreatic ductal carcinomas in Syrian hamsters.

Syrian golden hamsters were treated with N-nitrosobis-(2-oxopropyl)amine (BOP) and/or diethylstilbestrol (DES) for lifetime. After BOP treatment the hamsters developed high incidences of pancreatic neoplasms, but DES failed to show any effect on these or other tumours.