Quantification of Global DNA Methylation in Canine Mammary Gland Tumors via Immunostaining of 5-Methylcytosine: Histopathological and Clinical Correlations.

Mammary tumors are the most prevalent neoplasms in non-neutered female dogs, with genetic and epigenetic alterations contributing to canine mammary carcinogenesis. This study quantified global DNA methylation in 5-methylcytosine (5mC)-immunostained canine mammary tumor samples and established histopathological and clinical correlations. A total of 91 formalin-fixed paraffin-embedded mammary tumor samples from female dogs were retrospectively selected and subjected to immunohistochemistry using an anti-5mC mouse monoclonal antibody. We evaluated 5mC+ stained nuclei of neoplastic epithelial cells in canine mammary glands to obtain semiquantitative histoscores based on staining intensity. Survival rates were estimated based on owners' or veterinary records. Histological samples comprised 28 and 63 benign and malignant canine mammary gland tumors, respectively. Results revealed significant differences between global DNA methylation patterns when mammary samples were categorized as benign or malignant (p = 0.024), with hypomethylated patterns more prevalent in malignant tumors and those with higher relapse behavior (p = 0.011). Of note, large diameter (>5 cm) tumors revealed a lower methylation pattern (p = 0.028). Additionally, we found non-statistically significant differences when tumors were grouped by histopathological characteristics, clinical parameters, or survival. These findings propose global DNA methylation assessment as a promising tool for detecting canine mammary tumors with relapse propensity.

Global DNA methylation of peripheral blood leukocytes from dogs bearing multicentric non-Hodgkin lymphomas and healthy dogs: A comparative study.

Non-Hodgkin lymphomas are among the most common types of tumors in dogs, and they are currently accepted as comparative models of the disease in humans. Aberrant patterns of DNA methylation seem to play a key role in the development of hematopoietic neoplasms in humans, constitute a special mechanism of transcriptional control, and may be influenced by genetic and environmental factors. Blood leukocyte DNA global methylation has been poorly investigated in dogs. The aim of this study is to examine whether peripheral blood global DNA methylation is associated with canine multicentric lymphomas. Peripheral venous blood samples from ten healthy dogs and nine dogs bearing multicentric lymphomas were collected, and the buffy coat was separated. Global DNA methylation was analyzed by High Performance Liquid Chromatography (HPLC) and immunocytochemistry (ICC). In both analyses, leukocytes from dogs with lymphoma presented lower global DNA methylation than in healthy dogs (HPLC: p = 0.027/ 5MeCyt immunoreactivity scores: p = 0.015). Moderate correlation was observed between the results obtained by HPLC and ICC (correlation coefficient = 0.50). For the identification of differently methylated genes between both groups, the Infinium Human Methylation (HM) EPIC BeadChip (850K) was used. Of the 853,307 CpGs investigated in the microarray, there were 34,574 probes hybridized in the canine samples. From this total, significant difference was observed in the methylation level of 8433 regions, and through the homologous and orthologous similarities 525 differently methylated genes were identified between the two groups. This study is pioneer in suggesting that dogs bearing non-Hodgkin lymphoma presented DNA global hypomethylation of circulating leukocytes compared with healthy dogs. Although canine samples were used in an assay developed specifically for human DNA, it was possible to identify differently methylated genes and our results reiterate the importance of the use of peripheral blood leukocytes in cancer research and possible new biomarkers targets.

Breast cancer mortality and associated factors in São Paulo State, Brazil: an ecological analysis.

OBJECTIVE: Identify the factors associated with the age-standardised breast cancer mortality rate in the municipalities of State of São Paulo (SSP), Brazil, in the period from 2006 to 2012. DESIGN: Ecological study of the breast cancer mortality rate standardised by age, as the dependent variable, having each of the 645 municipalities in the SSP as the unit of analysis. SETTINGS: The female resident population aged 15 years or older, by age group and municipality, in 2009 (mid-term), obtained from public dataset (Informatics Department of the Unified Health System). PARTICIPANTS: Women 15 years or older who died of breast cancer in the SSP were selected for the calculation of the breast cancer mortality rate, according to the municipality and age group, from 2006 to 2012. MAIN OUTCOME MEASURES: Mortality rates for each municipality calculated by the direct standardisation method, using the age structure of the population of SSP in 2009 as the standard. RESULTS: In the final linear regression model, breast cancer mortality, in the municipal level, was directly associated with rates of nulliparity (p<0.0001), mammography (p<0.0001) and private healthcare (p=0.006). CONCLUSIONS: The findings that mammography ratio was associated, in the municipal level, with increased mortality add to the evidence of a probable overestimation of benefits and underestimation of risks associated with this form of screening. The same paradoxical trend of increased mortality with screening was found in recent individual-level studies, indicating the need to expand informed choice for patients, primary prevention actions and individualised screening. Additional studies should be conducted to explore if there is a causality link in this association.

Comparative Aspects of Canine Melanoma.

Melanomas are malignant neoplasms originating from melanocytes. They occur in most animal species, but the dog is considered the best animal model for the disease. Melanomas in dogs are most frequently found in the buccal cavity, but the skin, eyes, and digits are other common locations for these neoplasms. The aim of this review is to report etiological, epidemiological, pathological, and molecular aspects of melanomas in dogs. Furthermore, the particular biological behaviors of these tumors in the different body locations are shown. Insights into the therapeutic approaches are described. Surgery, chemotherapy, radiotherapy, immunotherapy, and the outcomes after these treatments are presented. New therapeutic perspectives are also depicted. All efforts are geared toward better characterization and control of malignant melanomas in dogs, for the benefit of these companion animals, and also in an attempt to benefit the treatment of human melanomas.

Chemical carcinogenesis by DMBA (7, 12-dimethylbenzanthracene) in female BALB/c mice: new facts / Carcinogenese quimica por DMBA (7, 12-dimethylbenzanthracene) em camundongos femeas BALB/c: novos fatos

Polycyclic aromatic hydrocarbons are known carcinogens used in rodent experimental models. In this study, the carcinogen DMBA (7,12-dimethylbenzanthracene) was administered by gavage, diluted in corn oil, to female BALB / c mice at hebdomadary doses of 1 mg per animal for 1, 3, 6 or 9 weeks. Animals were weighed and monitored weekly until death. Remaining animals were euthanized at the age of 53 weeks. At necropsy, representative fragments of neoplasms were collected and routinely processed for histopathological analysis. Of all mice that received DMBA, 68.57% developed some type of tumor. Of the 70 mice treated with various doses of DMBA, 22 (31.43%) developed mammary tumors. The adenoacanthoma was the most commonly (18.75%) diagnosed histological type of breast cancer. Lung (15.71%), lymphoid tissue (11.43%), stomach (7.14%) and skin (2.86%) were also primary sites of tumor development. One third (33.33%) of the mice receiving 1 mg of DMBA developed lung cancer. Therefore, the administration of DMBA was shown to be an efficient model of carcinogenesis in mice, especially for the study of breast cancer, when using the highest dose, and lung, when using the lowest dose. Carcinogenesis models have been used for several purposes in cancer research. These results represent new facts for a classic carcinogenesis model.

Hidrocarbonetos policíclicos e aromáticos são carcinógenos usados em modelos experimentais em roedores. Neste estudo, o carcinógeno DMBA (7,12-dimetilbenzantraceno) foi administrado por gavagem, diluído em óleo de milho, para camundongos BALB/c em doses hebdomadárias de 1 mg por animal por 1, 3, 6 ou 9 semanas. Os animais foram pesados e monitorados semanalmente até a morte. Os animais remanescentes foram eutanasiados com a idade de 53 semanas. Na necroscopia, fragmentos representativos das neoplasias foram colhidos e rotineiramente processados para exame histopatológico. De todos os animais que receberam DMBA, 68,57% desenvolveram algum tipo de tumor. Entre os 70 camundongos tratados com diferentes doses de DMBA, 22 (31,43%) desenvolveram neoplasias mamárias. O adenoacantoma foi o tumor mamário mais comumente diagnosticado (18,75%). Pulmões (15,71%), tecido linfoide (11,43%), estômago (7,14%) e pele (2,86%) foram também locais primários de desenvolvimento de neoplasias. Um terço (33,33%) dos camundongos que receberam 1 mg de DMBA desenvolveram neoplasias pulmonares. Portanto, a administração de DMBA foi considerada um modelo eficiente de carcinogênese em camundongos, especialmente para o estudo de neoplasias mamárias, quando a maior dose é utilizada, e de neoplasias pulmonares, quando utilizada a menor dose. Os modelos de carcinogênese química têm sido usados para diversos estudos na pesquisa em câncer, os resultados aqui apresentados mostram novos fatos para um modelo clássico de carcinogênese.

Cartography of neoplasms in dogs from different regions of the city of São Paulo, SP, Brazil: a survey (2002-2003) of data from the Veterinary Hospital of the School of Veterinary Medicine and Animal Science of the University of São Paulo, Brazil / Cartografia das neoplasias em cães das diferentes regiões da cidade de São Paulo, SP, Brasil: um levantamento (2002-2003) dos dados do Hospital Veterinário da Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo, Brasil

Improvements in veterinary medicine have resulted in a significant benefit in the life of pets in the last 20 years, and increased pet life expectancy led to an increased prevalence of canine neoplasia. Cancer epidemiology and spatial analysis tools, although well developed for human oncology research, is just beginning to be explored in veterinary oncology. São Paulo city, capital of the state of São Paulo, Brazil, is divided into five regions: North, South, East, West and downtown. The Veterinary Hospital of the School of Veterinary Medicine and Animal Science, University of São Paulo (HOVET-SVMAS-USP), is located in the West region of São Paulo, Brazil, and admits cases of small and large animals. Canine mammary tumors are so numerous that they are not routinely treated at the HOVET. The aim of this work was to perform a cartographic study to describe the spatial distribution of prevalent cases of neoplasms in dogs from the HOVET. Of the 3,620 cases seen in 2002 and 2003, 380 cases (10.5%) were of dogs affected with benign and malignant neoplasms. No statistical difference was found for the 380 addresses distributed among the five regions of the city. These results showed that the HOVET receives canine patients from all regions of São Paulo and there is a homogeneous spatial distribution of neoplasms. Authors encourage additional broader studies, involving several veterinary hospitals, clinics or laboratories in order to obtain more accurate data on distribution of canine neoplasms in São Paulo, SP, Brazil.

Avanços na medicina veterinária resultaram em benefícios significativos na vida de animais de estimação nos últimos 20 anos, e o aumento da expectativa de vida para animais levou a uma maior prevalência de neoplasias em cães. A Epidemiologia do Câncer e as ferramentas de análise espacial, embora bem desenvolvidas na pesquisa oncológica humana, estão começando a serem exploradas na Oncologia Veterinária. A cidade de São Paulo, capital do estado de São Paulo, Brasil, é dividida em cinco regiões: Norte, Sul, Leste, Oeste e centro. O Hospital Veterinário da Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo (HOVET-SVMAS-USP) está localizado na região Oeste de São Paulo, Brasil, e admite casos de pequenos e grandes animais. Tumores mamários caninos são tão numerosos que não são tratados na rotina do HOVET. O objetivo deste trabalho foi realizar um estudo cartográfico para descrever a distribuição espacial dos casos prevalentes de neoplasias em cães a partir do HOVET. Dos 3.620 casos atendidos em 2002 e 2003, 380 (10,5%) casos eram de cães acometidos por tumores benignos e malignos. Não foi encontrada diferença estatística entre a distribuição dos 380 endereços entre as cinco regiões da cidade. Os resultados mostraram que o HOVET atende pacientes caninos de todas as regiões de São Paulo e que há uma distribuição espacial homogênea das neoplasias. Os autores incentivam estudos mais amplos, envolvendo vários hospitais veterinários, clínicas e laboratórios, a fim de obter dados mais precisos sobre a distribuição das neoplasias caninas em São Paulo, SP, Brasil.

Higher incidence of lung adenocarcinomas induced by DMBA in connexin 43 heterozygous knockout mice.

Gap junctions are communicating junctions which are important for tissue homeostasis, and their disruption is involved in carcinogenic processes. This study aimed to verify the influence of deletion of one allele of the Connexin 43 gene on cancer incidence in different organs. The 7, 12-dimethylbenzanthracene (DMBA) carcinogenic model, using hebdomadary doses by gavage of 9 mg per animal, was used to induce tumors in Connexin 43 heterozygous or wild-type mice. The experiment began in the eighth week of the mice life, and all of them were euthanized when reaching inadequate physical condition, or at the end of 53 weeks. No statistical differences occurred for weight gain and cancer survival time (P = 0.9853) between heterozygous and wild-type mice. Cx43⁺/⁻ mice presented significantly higher susceptibility to lung cancer (P = 0.0200) which was not evidenced for benign neoplasms (P = 0.3449). In addition, incidence of ovarian neoplasms was 2.5-fold higher in Cx43⁺/⁻ mice, although not statistically significant. Other organs showed a very similar cancer occurrence between Cx43 groups. The experiment strengthens the evidence of the relationship between Connexin 43 deficiency and carcinogenesis.