Perfil fenotípico de potenciais células iniciadoras tumorais no tumor venéreo transmissível canino ex vivo
Carregando...
Arquivos
Data
2016-02-29
Autores
Grandi, Fabrizio [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
O tumor venéreo transmissível (TVT) canino é uma neoplasia transplantável, considerada um alo-enxerto. Entretanto, pouco se sabe a respeito da origem e processo de cacinogênese. Atualmente, postula-se que alguns tumores originem-se de células iniciadoras tumorais, classicamente descritas nas leucemias mielóide humanas. As características intrínsecas do TVT fornecem indícios de uma possível participação de células iniciadores tumorais no processo de carcinogênese nesse tumor. Foi realizado estudo de fenotipagem do TVT canino para avaliar a marcação das proteínas CD44, CD133, CD90 e CD34, comumente associadas ao potencial iniciador tumoral. Para tanto utilizou-se a citometria de fluxo, imuno-histoquímica e RTq-PCR. Foram analisados também as frações de crescimento pelo Ki-67) e o número de células em apoptose pela caspase-3 clivada. Trinta e oito amostras de TVT foram obtidas de pacientes sem tratamento quimioterápico prévio. As amostras foram classificadas em plasmocitóide ou mistas, de acordo com o subtipo citológico; as células positivas na citometria de fluxo foram representadas em termos percentuais para os marcadores CD44, CD34, CD90 e CD133; a fração de crescimento foi representada pela técnica do H-Score; a quantidade de células apoptóticas foi representada pelo somatório de células positivas para a caspase-3 clivada; as imuno-marcações das proteínas CD44 e CD34 foram representadas por escores semi-quantitativos baseados na intensidade e percentual de células positivas; as expressões de RNAm foram calculadas em termos relativos; ainda, os pacientes foram divididos em grupos resistente e não resistente e comparados quanto a expressão dos marcadores de células iniciadoras supracitados. Não foram observadas diferenças significativas entre os marcadores e os grupos citológicos plasmocitóide e misto; o percentual de células CD44+ comumente foi superior a 90%, enquanto que o percentual de células CD34+, menor que 0,5%; o percentual de células CD90+ e CD133+ variou amplamente; houve uma tendência em termos de diferença estatística entre os grupos quimiorresistente e não resistente; houve correlação forte entre o percentual de células CD133+ e CD90+ na citometria de fluxo. O estudo permitiu verificar diferentes níveis de expressão protéica e gênica nas amostras de TVT canino; ainda, os grupos citológicos aparentam não possuir diferenças com relação a expressão dos marcadores CD44, CD90, CD133 e CD34; os grupos quimiorresistentes e não-resistentes parecem diferir com relação a expressão dos marcadores de células iniciadoras tumorais.
The canine transmissible venereal tumor (CTVT) is a transplantable neoplasia considered an allograft. Information about the origin and carcinogenesis process is scarcely known. Currently, some neoplasms are believed to arise from a tumor-initiating cell (TIC´s) classically described in human myeloid leukemia. TVT intrinsic characteristics provide evidence of a possible TIC´s participation in carcinogenesis process of this malignancy. Thus, a phenotyping study of CTVT was conducted to assess the immunophenotyping properties of the proteins CD44, CD133, CD90 and CD34, already known to be associated to tumor initiator potential. The use of flow cytometry and immunohistochemistry contributed to this purpose. In addition, growth fractions and cells undergoing apoptosis were examined by Ki-67 and caspase-3 cleaved, respectively. Thirty-eight samples were chosen from patients having no previous chemotherapy and cytological diagnosis of CTVT. Samples were classified into plasmacytoid or mixed according to cytological subtype. Positive cells in the flow cytometry were expressed in percentage for the markers CD44, CD34, CD90 and CD133. H-score technique helped to represent growth fractions. Apoptotic cell quantity was calculated by summing positive cells. Immunohistochemical marking of CD44 and CD34 proteins were determined by semiquantitative scores based on the intensity and percentage of positive cells. Moreover, specimens were divided into resistant and non-resistant groups and compared according cell marker expressions cited before. No significant differences appeared between the markers, and cytological plasmacytoid and mixed groups. The CD44 + cells and CD34 + percentages showed up high and low values, respectively. CD90 + and CD133 + cell percentages presented variable values. Amplitudes of the gene expression values among markers were similar to those observed in flow cytometry with a low expression of CD34, and a high expression of CD44. There was a positive statistical tendence between chemo-resistant and non-resistant groups, as well as a strong correlation between the percentage of CD133 + and CD90 + in flow cytometry. Besides, cytological groups apparently have no differences with the marker expression of CD44, CD90, CD133 and CD34. Resistant and non-resistant groups to chemotherapy seems to differ with respect to the marker expression of TIC´s.
The canine transmissible venereal tumor (CTVT) is a transplantable neoplasia considered an allograft. Information about the origin and carcinogenesis process is scarcely known. Currently, some neoplasms are believed to arise from a tumor-initiating cell (TIC´s) classically described in human myeloid leukemia. TVT intrinsic characteristics provide evidence of a possible TIC´s participation in carcinogenesis process of this malignancy. Thus, a phenotyping study of CTVT was conducted to assess the immunophenotyping properties of the proteins CD44, CD133, CD90 and CD34, already known to be associated to tumor initiator potential. The use of flow cytometry and immunohistochemistry contributed to this purpose. In addition, growth fractions and cells undergoing apoptosis were examined by Ki-67 and caspase-3 cleaved, respectively. Thirty-eight samples were chosen from patients having no previous chemotherapy and cytological diagnosis of CTVT. Samples were classified into plasmacytoid or mixed according to cytological subtype. Positive cells in the flow cytometry were expressed in percentage for the markers CD44, CD34, CD90 and CD133. H-score technique helped to represent growth fractions. Apoptotic cell quantity was calculated by summing positive cells. Immunohistochemical marking of CD44 and CD34 proteins were determined by semiquantitative scores based on the intensity and percentage of positive cells. Moreover, specimens were divided into resistant and non-resistant groups and compared according cell marker expressions cited before. No significant differences appeared between the markers, and cytological plasmacytoid and mixed groups. The CD44 + cells and CD34 + percentages showed up high and low values, respectively. CD90 + and CD133 + cell percentages presented variable values. Amplitudes of the gene expression values among markers were similar to those observed in flow cytometry with a low expression of CD34, and a high expression of CD44. There was a positive statistical tendence between chemo-resistant and non-resistant groups, as well as a strong correlation between the percentage of CD133 + and CD90 + in flow cytometry. Besides, cytological groups apparently have no differences with the marker expression of CD44, CD90, CD133 and CD34. Resistant and non-resistant groups to chemotherapy seems to differ with respect to the marker expression of TIC´s.
Descrição
Palavras-chave
Tumor venéreo transmissível canino, Células tronco, Células iniciadoras tumorais, Carcinogênese, Neoplasia, Canine transmissible venereal tumor, Stem cells, Cancer stem cells, Carcinogenesis