Expression of Class II β-Tubulin by Proliferative Myoepithelial Cells in Canine Mammary Mixed Tumors

Canine Mammary Tumors: Classification, Biomarkers, Traditional and Personalized Therapies

In recent years, many studies have focused their attention on the dog as a proper animal model for human cancer. In dogs, mammary tumors develop spontaneously, involving a complex interplay between tumor cells and the immune system and revealing several molecular and clinical similarities to human breast cancer. In this review, we summarized the major features of canine mammary tumor, risk factors, and the most important biomarkers used for diagnosis and treatment. Traditional therapy of mammary tumors in dogs includes surgery, which is the first choice, followed by chemotherapy, radiotherapy, or hormonal therapy. However, these therapeutic strategies may not always be sufficient on their own; advancements in understanding cancer mechanisms and the development of innovative treatments offer hope for improved outcomes for oncologic patients. There is still a growing interest in the use of personalized medicine, which should play an irreplaceable role in the research not only in human cancer therapy, but also in veterinary oncology. Moreover, immunotherapy may represent a novel and promising therapeutic option in canine mammary cancers. The study of novel therapeutic approaches is essential for future research in both human and veterinary oncology.

An Essential Role of Maspin in Embryogenesis and Tumor Suppression

Maspin (SerpinB5) is an epithelial-specific tumor suppressor gene product that displays context-dependent cellular functions. Maspin-deficient mouse models created to date have not definitively established maspin functions critical for cancer suppression. In this study, we generated a mouse strain in which exon 4 of the Maspin gene was deleted, confirming its essential role in development but also enabling a breeding scheme to bypass embryonic lethality. Phenotypic characterization of this viable strain established that maspin deficiency was associated with a reduction in maximum body weight and a variety of context-dependent epithelial abnormalities. Specifically, maspin-deficient mice exhibited pulmonary adenocarcinoma, myoepithelial hyperplasia of the mammary gland, hyperplasia of luminal cells of dorsolateral and anterior prostate, and atrophy of luminal cells of ventral prostate and stratum spinosum of epidermis. These cancer phenotypes were accompanied by increased inflammatory stroma. These mice also displayed the autoimmune disorder alopecia aerate. Overall, our findings defined context-specific tumor suppressor roles for maspin in a clinically relevant model to study maspin functions in cancer and other pathologies. Cancer Res; 77(4); 886-96. ©2017 AACR.

Canine mammary mixed tumours: a review

Mammary mixed tumours are the most frequent neoplasias in female dogs. In humans, mixed tumours are frequently found in the salivary glands and are known as pleomorphic adenomas. In addition to their histomorphologic similarities, mixed tumours and pleomorphic adenomas have the potential to become malignant and give rise to carcinomas in mixed tumours and carcinomas ex-pleomorphic adenoma, respectively. The factors associated with malignant transformation are still poorly known in the case of canine mixed tumours. However, this form of neoplasia tends to be associated with a better prognosis than other malignant histological types. This paper discusses the main features associated with female canine mammary mixed tumours.

Development, anatomy, histology, lymphatic drainage, clinical features, and cell differentiation markers of canine mammary gland neoplasms

Mammary neoplasms are the most common neoplasm in female dogs. This article describes the embryologic development, normal anatomy, and histology of the canine mammary gland from the onset of first estrous and the changes that occur in the mammary gland during the estrus cycle. The clinical features of canine mammary gland tumors and their relation to prognosis are discussed, including age, hormones, breed, diet, and obesity. Additional clinical prognostic factors including clinical presentation, tumor size, and lymph node status at the time of presentation are discussed in relation to diagnosis and tumor staging. Immunohistochemical evaluation of the cell differentiation markers of the normal and neoplastic canine mammary gland is described and compared with similar studies in humans; the ways these markers may be used to assist with the prognosis of canine mammary neoplasms are discussed.

Co-localization of chondromodulin-I (ChM-I) and bone morphogenetic protein-6 (BMP-6) in myoepithelial cells of canine mammary tumors

To compare the roles of chondromodulin-I (ChM-I) and bone morphogenetic protein-6 (BMP-6) in ectopic mesenchymal tissue formation in canine mammary gland tumors, 33 tumors and 2 normal mammary glands were examined. Immunohistochemical analysis revealed co-expression of ChM-I and BMP-6 in canine mammary tumors. In mixed tumors, newly formed woven bone with ossified cartilage matrix was observed in 4/9 cases. The osteoblasts lining the woven bone showed moderate immunoreactivity to ChM-I and BMP-6. Almost all chondrocytes and proliferative myoepithelial cells within the basement membrane showed intense immunoreactivity to both, and the myoepithelial cells adjacent to the mature cartilage showed the most intense immunoreactivity. The immunoreactivity to ChM-I and BMP-6 of the interstitial myoepithelial cells in the myxomatous stroma varied in each focus of mixed tumors. Similar findings were found in complex adenomas. In simple adenomas, hyperplasic myoepithelial cells within the basement membrane showed moderate immunoreactivity to both markers. Western blot analysis detected a 25 kDa band of ChM-I in fresh tissue samples from three mixed tumors. Our results support the hypothesis that proliferating myoepithelial cells with ChM-I and BMP-6 expression play important roles in mesenchymal metaplasia in canine mammary tumors.

Regulation of Class II β-Tubulin Expression by Tumor Suppressor p53 Protein in Mouse Melanoma Cells in Response toVincaAlkaloid

The continuous exposure of antimicrotubule drugs to tumors often results in the emergence of drug-resistant tumor cells with altered expression of several beta-tubulin isotypes. We found that Vinca alkaloid enhanced expression of class II beta-tubulin isotype (mTUBB2) in mouse B16F10 melanoma cells via alteration of the tumor suppressor p53 protein. Vincristine treatment stimulated an increase in mTUBB2 mRNA expression and promoted accumulation of this isotype around the nuclei. Transient transfection assays employing a reporter construct, together with site-directed mutagenesis studies, suggested that the p53-binding site found in the first intron was a critical region for mTUBB2 expression. Electrophoretic mobility shift assay and associated antibody supershift experiments showed that vincristine promoted release of p53 protein from the binding site. In addition, exogenous induction of TAp63gamma (p51A), a homologue of p53, canceled the effect of vincristine on mTUBB2 expression. These results suggest that p53 protein may function as a suppressor of mTUBB2 expression and vincristine-mediated inhibition of p53 binding results in enhanced mTUBB2 expression. This phenomenon could be related with the emergence of drug-resistant tumor cells induced by Vinca alkaloid and may participate in determining the fate of these cells.

Immunohistochemical distribution of tubulin beta II in human normal and neoplastic tissues

Tubulin is the major constituent protein of microtubules. In mammals, there are seven beta-tubulins and six alpha-tubulins. Each beta-tubulin isotype has a unique tissue distribution. The purpose of this study was to describe the distribution of tubulin beta II in normal and neoplastic human tissues with immunohistochemical techniques. We obtained normal tissues from 33 cases (8 fetuses, 17 neonates, 3 children and 5 adults) and 121 samples of neoplastic tissue from surgical specimens or at autopsy. Immunohistochemical staining for tubulin beta II was performed using a monoclonal antibody, KNY379 developed in our laboratory. Tubulin beta II was detected in various normal tissues, particularly in fetal and neonatal tissues, such as the nervous system, pulmonary alveoli, bronchioles and bronchi, colon, pancreatic ducts and acini, renal convoluted tubuli, skin epidermis, body cavity mesothelial cells, smooth muscle and thymus. In the adult, broad expression was also observed; however, the immunoreactivity was weaker and the extent of its distribution decreased with age. In neoplastic tissues, tubulin beta II immunoreactivity was detected in various nervous system neoplasms and other neoplasms such as pancreatic solid cystic carcinoma, pleomorphic adenoma, Warthin's tumor, nephroblastoma, basal cell carcinoma and malignant mesothelioma. We conclude that our monoclonal antibody, KNY379, may be useful as a marker of nervous system neoplasm, pancreatic solid cystic carcinoma, pleomorphic adenoma, Warthin's tumor, nephroblastoma, basal cell carcinoma and malignant mesothelioma.