Low-grade and high-grade mammary carcinomas in WAP-T transgenic mice are independent entities distinguished by Met expression.

Mammary carcinomas developing in SV40 transgenic WAP-T mice arise in two distinct histological phenotypes: as differentiated low-grade and undifferentiated high-grade tumors. We integrated different types of information such as histological grading, analysis of aCGH-based gene copy number and gene expression profiling to provide a comprehensive molecular description of mammary tumors in WAP-T mice. Applying a novel procedure for the correlation of gene copy number with gene expression on a global scale, we observed in tumor samples a global coherence between genotype and transcription. This coherence can be interpreted as a matched transcriptional regulation inherited from the cells of tumor origin and determined by the activity of cancer driver genes. Despite common recurrent genomic aberrations, e.g. gain of chr. 15 in most WAP-T tumors, loss of chr. 19 frequently occurs only in low-grade tumors. These tumors show features of "basal-like" epithelial differentiation, particularly expression of keratin 14. The high-grade tumors are clearly separated from the low-grade tumors by strong expression of the Met gene and by coexpression of epithelial (e.g. keratin 18) and mesenchymal (e.g. vimentin) markers. In high-grade tumors, the expression of the nonmutated Met protein is associated with Met-locus amplification and Met activity. The role of Met as a cancer driver gene is supported by the contribution of active Met signaling to motility and growth of mammary tumor-derived cells. Finally, we discuss the independent origin of low- and high-grade tumors from distinct cells of tumor origin, possibly luminal progenitors, distinguished by Met gene expression and Met signaling.

Mutant p53 promotes epithelial-mesenchymal plasticity and enhances metastasis in mammary carcinomas of WAP-T mice.

To study the postulated mutant p53 (mutp53) "gain of function" effects in mammary tumor development, progression and metastasis, we crossed SV40 transgenic WAP-T mice with mutant p53 transgenic WAP-mutp53 mice. Compared to tumors in monotransgenic WAP-T mice, tumors in bitransgenic WAP-T x WAP-mutp53 mice showed higher tumor grading, enhanced vascularization, and significantly increased metastasis. Bitransgenic tumors revealed a gene signature associated with the oncogenic epithelial-mesenchymal transition pathway (EMT gene signature). In cultures of WAP-T tumor-derived G-2 cancer cells, which are comprised of subpopulations displaying "mesenchymal" and "epithelial" phenotypes, this EMT gene signature was associated with the "mesenchymal" compartment. Furthermore, ectopic expression of mutp53 in G-2 cells sufficed to induce a strong EMT phenotype. In contrast to these in vitro effects, monotransgenic and bitransgenic tumors were phenotypically similar suggesting that in vivo the tumor cell phenotype might be under control of the tumor microenvironment. In support, orthotopic transplantation of G-2 cells as well as of G-2 cells expressing ectopic mutp53 into syngeneic mice resulted in tumors with a predominantly epithelial phenotype, closely similar to that of endogenous primary tumors. We conclude that induction of an EMT gene signature by mutp53 in bitransgenic tumors primarily promotes tumor cell plasticity, that is, the probability of tumor cells to undergo EMT processes under appropriate stimuli, thereby possibly increasing their potential to disseminate and metastasize.

Immunodetection of myeloid and plasmacytoid dendritic cells in mammary carcinomas of female dogs

ABSTRACT: Dendritic cells have attracted great interest from researchers as they may be used as targets of tumor immune evasion mechanisms. The main objective of this study was to evaluate the relationship between the dendritic cells (DCs) subpopulation in simple type mammary carcinomas in female dogs. Two groups of samples were used: the control group consisted of 18 samples of mammary tissue without changes and the tumor group with 26 simple type mammary carcinomas. In these groups, we evaluated the immunodetection of immature and mature myeloid DCs, plasmacytoid DCs and MHC-II. In mammary tumor, mature myeloid DCs predominated in the peritumoral region, while immature myeloid DCs and plasmacytoid DCs were evident in the intratumoral region. Immunostaining of MHC-II was visualized in mammary acini (control group), in tumor cells and inflammatory infiltration associated with tumors. The comparison between the control and tumor groups showed a statistically significant difference between immature myeloid DCs, mature myeloid DCs and plasmacytoid DCs. The immunodetection of MHC-II was not significant when comparing the groups. The predominance of immature DCs in the tumor group is possibly related to an inefficient immune response, promoting the development and survival of tumor cells. The presence of plasmacytoid DCs in the same group suggests a worse prognosis for female dogs with mammary tumors. Therefore, the ability of differentiation of canine dendritic cells could be influenced by neoplastic cells and by the tumor microenvironment.

Clinical and molecular characterization of feline mammary carcinomas overexpressing HER2 proto-oncogene (FMC-HER2+) : new strategies for effective diagnostic and cancer therapy

Tese de Doutoramento em Ciências Veterinárias na Especialidade de Ciências Biológicas e Biomédicas

Carcinomas mamários de tipo basal: perfil clínico-patológico e evolutivo

OBJETIVO: Investigar a frequência de carcinomas mamários de fenótipo basal em uma série de tumores triplo-negativos (TTN), definidos pela negatividade para receptores de estrógeno (RE), de progesterona (RP) e HER2. MÉTODOS: Selecionamos 140 TTN, obtendo-se características clínico-patológicas e sobrevida. Microarranjo de tecido (2 cilindros de cada tumor) foi construído e submetido à imunoistoquímica para RE, RP, HER2, citoqueratinas (Cks) 5 e 14, EGFR, p63 e p53. Consideramos carcinomas de fenótipo basal os tumores negativos para RE, RP e HER2, e positivos para CK5. RESULTADOS: Encontramos 105 carcinomas de fenótipo basal entre 140 TTN (frequência=75%). A idade média das pacientes foi de 54,8 anos, sendo que 34,3% estavam na pré-menopausa. A maioria dos tumores foi classificada como carcinoma ductal invasor de alto grau. Os TTN exibiram positividade para CK5 (75,0%), CK14 (29%), EGFR (36,4%), p63 (28,6%) e p53 (67,1%). Estadiamento avançado da doença foi observado em 52 pacientes (50%), com diâmetro tumoral maior que 5 cm em 41 casos (39%) e metástases axilares em 61 casos (59,2%). Seguimento clínico foi obtido em 89 pacientes (média=51 meses). Destas, 45 pacientes (50,5%) evoluíram sem doença; 6 (6,7%) estavam vivas com doença e 38 (42,6%) morreram pelo câncer. Recidiva sistêmica ocorreu em 42 pacientes (47,1%), sendo pulmões, cérebro e ossos os principais sítios de metástases. As médias das sobrevidas global e livre de doença foram de 36 e 28 meses, respectivamente. CONCLUSÕES: Nosso estudo confirma comportamento clínico agressivo e elevada frequência dos carcinomas de fenótipo basal entre os TTN, semelhante ao descrito em casuísticas norte-americanas e europeias.

Retrovirus-host interactions. The mouse mammary tumor virus model.

Mouse mammary tumor virus (MMTV) is a retrovirus which can induce mammary carcinomas in mice late in life by activation of proto-oncogenes after integration in their vicinity. Surprisingly, it requires a functional immune system to achieve efficient infection of the mammary gland. This requirement became clear when it was discovered that it has developed strategies to exploit the immune response. Instead of escaping immune detection, it induces a vigorous polyclonal T-B interaction which is required to induce a chronic infection. This is achieved by activating and then infecting antigen presenting cells (B cells), expressing a superantigen on their cell surface and triggering unlimited help by the large number of superantigen-specific T cells. The end result of this strong T-B interaction is the proliferation and differentiation of the infected B cells leading to their long term survival.

Análise prognóstica da imunoexpressão de proteínas relacionadas à transição epitelial-mesenquimal nos carcinomas mamários esporádicos de cadelas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Avaliação da expressão dos genes TGFBR1 e TGFBR2 em amostras de carcinomas ductais invasivos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Relação entre o infiltrado inflamatório e as células dendríticas na resposta imune aos carcinomas do tipo simples em mama de cadelas

Pós-graduação em Medicina Veterinária - FCAV

Análise prognóstica da imunoexpressão de osteopontina no microambiente dos carcinomas mamários esporádicos de cadelas

Pós-graduação em Patologia - FMB

Use of surgery and carboplatin in feline malignant mammary gland neoplasms with advanced clinical staging

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Caracterização imuno-histoquímica de células do infiltrado inflamatório e de citocinas pró e anti-inflamatórias nos carcinomas mamários caninos

Pós-graduação em Medicina Veterinária - FCAV

Avaliação da quimioterapia metronômica em carcinomas mamários de cadelas por imunomarcações

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Phenotypic characterization of the epithelial and myoepithelial components in canine and feline mammary tumours

In veterinary medicine, the ability to classify mammary tumours based on the molecular profile and also determine whether the immunophenotype of the regional lymph node and/or systemic metastases is equal to that of the primary tumor may be predictive on the estimation of the effectiveness of various cancer treatments that can be scheduled. Therefore, aims, developed as projects, of the past three years have been (1) to define the molecular phenotype of feline mammary carcinomas and their lymph node metastases according to a previous modified algorithm and to demonstrate the concordance or discordance of the molecular profile between the primary tumour and lymph node metastasis, (2) to analyze, in female dogs, the relationship between the primary mammary tumor and its lymph node metastasis based on immunohistochemical molecular characterization in order to develop the most specific prognostic-predictive models and targeted therapeutic options, and (3) to evaluate the molecular trend of cancer from its primary location to systemic metastases in three cats and two dogs with mammary tumors. The studies on mammary tumours, particularly in dogs, have drawn gradually increasing attention not exclusively to the epithelial component, but also to the myoepithelial cells. The lack of complete information on a valid panel of markers for the identification of these cells in the normal and neoplastic mammary gland and lack of investigation of immunohistochemical changes from an epithelial to a mesenchymal phenotype, was the aim of a parallel research. While investigating mammary tumours, it was noticed that only few studies had focused on the expression of CD117. Therefore, it was decided to further deepen the knowledge in order to characterize the immunohistochemical staining of CD117 in normal and neoplastic mammary tissue of the dog, and to correlate CD117 immunohistochemical results with mammary histotype, histological stage (invasiveness), Ki67 index and patient survival time.