Behavior of CD44 Receptors in Mammary Tumors of Dogs

CD44 is a cell adhesion molecule closely related to tumor progression in humans. In canine mammary tumors, little information is available about this molecule. The aim of this study was to analyze, by immunohistochemistry, the behavior of this molecule in canine mammary tumors with or without the presence of metastasis. The dogs were divided in groups without metastasis (G1) and with metastasis (G2, with subsets A—original neoplasia and B—metastatic neoplasia). Tumors were classified according to the World Health Organization (WHO) criteria. The cells were counted whereby the plasma membrane and/or cytoplasm are stained. There was a significant increase in the number of cells immunostained for CD44 in the metastastic masses (G2B) as compared to groups G1 and G2A. It is concluded that in metastatic mass there was a significant increase in CD44 receptors, probably important for biology of the mammary tumor of dogs.

Dampness-Heat Accelerates DMBA-Induced Mammary Tumors in Rats

Objective： To investigate the impact of dampness-heat （DH） on the development of mammary tumors in 7,12-dimethylbenz（a）anthracene （DMBA）-induced rats. Methods： Forty rats were randomly divided into 3 groups in a randomized block design, including the control group （n=13）, DMBA group （n=14）, and DMBA plus DH group （n=13）. Rats in the DMBA group and DMBA plus DH group were intragastrically administrated with DMBA （100 mg/kg） for twice, once per week, while rats in the control group were treated with equivalent volumes of sesame oil. After DMBA administration, rats in the DMBA plus DH group were exposed to a simulated climate chamber with ambient temperature （33.0 ± 0.5 ℃） and humidity （90% ± 5%） for 8 weeks, 8 h per day. The body weight, time of tumor formation, and number of tumors were measured weekly to calculate tumor incidence, average latency period, average number of tumors, and average tumor weight. At the end of the experiment, the levels of matrix metalloproteinase 9 （MMP-9） and tissue inhibitor of metalloproteinases 1 （TIMP-1） in serum, and the contents of tumor necrosis factor- α （TNF- α ） and interleukin （IL）-1β in serum and tumor tissue were measured, respectively. Some tumor tissues were processed for hematoxylin-eosin staining to determine the histopathological changes. Results： Compared with DMBA, DMBA plus DH significantly increased the average number of tumors, average tumor weight, levels of serum MMP-9, TiMP-1, TNF- α and IL-1β, and contents of tumor tissue TNF- α and IL-1β （P〈0.05 or P〈0.01）. Conclusion： DH could accelerate the development of mammary tumors through increasing the expressions of MMP-9, TIMP-1, TNF- α and IL-1β in DMBA-induced rats.

Investigation on the mechanism of ginsenoside Rg3 in treating murine primary mammary tumor

A murine primary mammary tumor model was established to investigate the treatment with ginsenosides Rg3.The relationship between ginsenosides Rg3 and primary mammary tumor was explored.Mammary tumor was induced by using the 7,12-dimethybenz(a)anthracene(DMBA).Ginsenoside Rg3 was employed for treatment.The incidence of mammary tumor in every group was compared,and the expressions of vascular endothelial growth factor(VEGF)and microvessel density(MVD)were detected by immunohistochemical method.The cell cycle and apoptosis percentage were determined by means offlow cytometry.The incidence of tumor in treatment group was significantly lower than that in control group(60.00%vs 33.33%,P<0.05).The average diameter of mammary tumor was(0.86�0.27)cm in control group and(0.39�0.09)cm in treatment group,with the difference being significant between control and treatment groups(P<0.01).The MVD value was(31.9�5.3)in control group and(20.1�4.9)in treatment group,respectively.There was a significant difference between the two groups(P<0.05).The apoptosis percentage in control group was significantly lower than that in treatment group[(2.47�0.69)%vs(5.67�0.99)%,P<0.05].Ginsenoside Rg3 can play an antitumor role in primary mammary tumor model by inhibiting angiogenesis,cell cycle progression,and promoting cell apoptosis.

Snai-1 and Epithelial-Mesenchymal Transition-Related Protein Immunoexpression in Canine Mammary Carcinomas

Epithelial-mesenchymal transition (EMT) is defined as switching of polarized epithelial cells to a migratory fibroblastoid phenotype. EMT is known to be involved in the progression and metastasis of various cancers in humans, but this specific process is still little explored in the veterinary literature. The aim of this research was to evaluate the expression of EMT-related proteins in canine mammary carcinomas (CMCs). The expression of six EMT-related proteins in 94 CMCs of female dogs was evaluated by immunohistochemistry using a tissue array method. Additionally, clinicopathological characteristics were compared with the expression of EMT-related proteins. Loss of epithelial protein and/or acquisition of the expression of mesenchymal proteins were observed in CMCs. Loss of epithelial protein and/or acquisition of the expression of mesenchymal proteins were observed, particularly in tumors with evidence of stromal invasion;however, significance was only observed between the S100A4 and vascular invasion. In addition, Snai-1 nuclear immunoexpression was significantly related to E-cadherin loss. In conclusion, loss of epithelial proteins and/or the acquisition of mesenchymal proteins are associated with EMT and may have an important role in the evaluation of CMC patients. The unique immunoexpression pattern of Snai-1 could help to distinguish between an adenoma and a non-metastatic carcinoma and seems to be related to conversion of myoepithelial cells to a complete mesenchymal-like phenotype. Loss of E-cadherin and cytokeratin and change of immunoexpression pattern of Snai-1, N-cadherin, S100A4 and MMP-2 indicate the occurrence of EMT in canine mammary carcinomas and should result in an en bloc resection or a close follow-up.

Immunoexpression of Cathepsin D and S100A4 Protein and Their Molecular Subtyptes in Canine Mammary Carcinomas

Cathepsin D (CD), a lysosomal protease, and S100A4 protein, a calcium binding motif, are considered to be involved in metastasis in various human cancers. No data regarding such proteins are available for canine mammary carcinomas (CMCs). Accordingly, their expression in association with known factors of prognosis was investigated in this study. For that, 66 surgically resected CMCs were submitted to an immunohistochemical evaluation using anti CD, S100A4 protein, HER2, estrogen receptor α, cytokeratin 5, and p63 antibodies, further characterizing the tumors' molecular subtype. An increase in S100A4 immunoexpression by neoplastic luminal mammary cells was associated with an infiltrative tumor mode of growth, consequently leading us to conclude that S100A4 protein could be related to progression in CMCs. Additionally, the occurrence of the luminal A molecular subtype was associated with the complex histotype in CMCs. Although we have demonstrated that changes in S100A4 protein immunoexpression occurs in CMCs, further studies are needed to determine whether this represents important independent biomarkers for CMCs.

Tetramethrin Identified in Fat Adjacent to Mammary Carcinoma in a Male Dog—Case Report

Canine mammary tumors (CMT) are very common in female dogs, representing approximately 50% of all tumors in this species, but are highly uncommon in male dogs and are primarily related to hyperestrogenism. There is considerable scientific interest in the possible role of environmental contaminants in the etiology of mammary tumors, specifically in relation to synthetic chemical substances released into the environment to which living beings are either directly or indirectly exposed. In this study, the presence of pyrethroid insecticide was observed in adipose tissue adjacent to canine mammary tumors. High Precision Liquid Chromatography—HPLC was adapted to detect and identify environmental contaminants in adipose tissue adjacent to malignant mammary tumor in one male dog, Akita, 12 years old. After surgery, the mass was carefully examined for malignant neoplastic lesions. Five grams of adipose tissue adjacent to the tumor was collected to detect environmental contaminants. The pyrethroid was identified as tetramethrin, at 0.20 μg/g. This is the first report in which the environmental contaminant level was detectable in adipose tissue of this male dog with a malignant mammary tumor, by HPLC. Results suggest the possible involvement of pyrethroid in the canine mammary tumor carcinogenesis since this animal did not present any other tumor that could cause hyperestrogenism.