Avaliação do C-MYC, BCL2, KI67 e índice mitótico como fatores prognósticos em cães com linfoma difuso de grandes células B
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Data
2016-02-26
Autores
Sierra Matiz, Oscar Rodrigo [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O linfoma difuso de grandes células B (LDGCB) é o tipo de linfoma mais comum em cães e humanos, caracterizado por seu comportamento agressivo e por promover tempos de sobrevida variáveis, mesmo quando se utiliza a mesma abordagem terapêutica. Atualmente, poucos fatores prognósticos tem sido associados especificamente com LDGCB canino. A imunoexpressão de C-MYC e Bcl2 é reconhecida em humanos como fator prognóstico, devido a relação desses oncogenes com proliferação celular e evasão da apoptose nessa doença. O objetivo desse estudo foi avaliar a imunomarcação dos anticorpos C-MYC, Bcl2, e marcadores de proliferação celular Ki67 e índice mitótico (IM) em cães com LDGCB tratados com protocolo CHOP 19 semanas e correlacioná-la com o tempo de sobrevida e estadiamento clínico visando defini-los como possíveis fatores prognósticos. Trinta amostras de linfonodos de cães diagnosticados com LDGCB foram avaliadas. Para determinar a marcação de C-MYC, Bcl2 e Ki67 foi realizada a técnica de imuno-histoquímica utilizando-se os anticorpos C-MYC, Bcl2 (Santa Cruz Biotechnology) e MIB-1 (Dako), respetivamente. O IM foi calculado como descrito para outras neoplasias. A interpretação dos resultados da imuno-histoquímica para C-MYC e Bcl2, foi calculada no porcentagem de área do número de células marcadas, enquanto a contagem de Ki67 foi realizada com auxílio de uma gratícula, contando-se células positivas por área de 1 cm². Foram estabelecidos pontos de corte, calculando-se a média para todos os marcadores, e posteriormente os valores do C-MYC, Bcl2, Ki67 e a IM foram classificados e definidos como “baixo” ou “alto”. Amostras classificadas como alto C-MYC e alto Bcl2, concomitantemente, foram definidas como alvo duplo MYC/Bcl2. A média de C-MYC foi de 21 (intervalo: 2,5-53,5), de Bcl2 foi de 32,5 (intervalo: 16,9 – 76,8), de Ki67 foi de 107 (intervalo: 1 – 446) e de IM foi de 21 (intervalo: 0-73). Quando comparados os tempos de sobrevida para cada marcador, observou-se que o Ki67 apresentou diferença significativa entre as médias dos grupos baixo (281 dias) e alto (91 dias) (p<0,05). Não houve relação do alvo duplo MYC/Bcl2 com tempos de sobrevida (p>0,05), assim como não houve associação entre a imunomarcação dos anticorpos com o estadiamento clínico. Porém, houve correlação positiva entre C-MYC e Bcl2 (p<0,05) e entre Ki67 e IM (p<0,0001). A expressão imuno-histoquímica dos anticorpos C-MYC e Bcl2, individualmente ou em alvo duplo, não parece constituir um fator prognóstico em cães com LDGCB. Porém, valores acima de 107 células positivas de Ki67 podem estar associados com tempos de sobrevida mais curtos em cães com LDGCB tratados com protocolo CHOP 19 semanas.
Diffuse large B cell lymphoma (DLBCL) is the most common type of lymphoma in dogs and humans, being characterized by its aggressive behavior with variable survival times, even when same therapeutic approach is used. Currently, few prognostic factors are described in the literature regarding canine DLBCL. Immunoexpression of C-MYC and Bcl2 is recognized in humans as a prognostic factor in DLBCL, product of the relationship between these oncogenes with cellular proliferation and apoptosis escape. The objective of this study is to evaluate the immunolabeling of C-MYC, Bcl2, and markers of cellular proliferation Ki67 and mitotic index (MI) in dogs with DLBCL treated with 19 weeks CHOP protocol and correlate them to survival times and clinical stage in order to identify new prognostic factors. Thirty lymphnode samples of dogs diagnosed with DLBCL were evaluated. For immunoexpression of C-MYC, Bcl2 and Ki67, we perform immunohistochemistry using the antibodies C-MYC, Bcl2 (Santa Cruz Biotechnology) and MIB-1 (Dako), respectively. MI was calculated as previously discussed in other tumors. The interpretation of the immunohistochemistry results for C-MYC and Bcl2 was based on the expression level of the area of positive cells, whereas a grid reticle was used for counting Ki67 positive cells in a total area of 1 cm². Cutoff values for all markers were established calculating the mean value and then the C-MYC Bcl2, Ki67 and MI values were classified and defined as “low” and “high”. Cases classified as high C-MYC and high Bcl2, were defined as double target MYC/Bcl2. Mean values were 21 (range: 2,5-53,5) for C-MYC, 32,5 (range: 16,9-76,8) for Bcl2, 107 (range: 1-446) for Ki67 and 21 (range: 0-73) for MI. Only Ki67 immunoexpression was found to be statistical different when survival times were compared between groups low and high (281 days vs 91 days). When double target MYC/Bcl2 was analyzed, no relationship was identified with survival times (p>0,05). Additionally, an association between the antibodies immunoexpression and clinical staging was not identified. However, a positive correlation between C-MYC and Bcl2 (p<0,05) and, Ki67 and MI (P<0,0001) was established. The immunohistochemistry expression of the antibodies C-MYC and Bcl2, individually or in double target, does not appear to constitute a prognostic factor in dogs with DLBCL, whereas a value of Ki67>107 positive cells can be used in dogs with DLBCL to foresee shorter survival times when treated with 19 weeks CHOP protocol.
Diffuse large B cell lymphoma (DLBCL) is the most common type of lymphoma in dogs and humans, being characterized by its aggressive behavior with variable survival times, even when same therapeutic approach is used. Currently, few prognostic factors are described in the literature regarding canine DLBCL. Immunoexpression of C-MYC and Bcl2 is recognized in humans as a prognostic factor in DLBCL, product of the relationship between these oncogenes with cellular proliferation and apoptosis escape. The objective of this study is to evaluate the immunolabeling of C-MYC, Bcl2, and markers of cellular proliferation Ki67 and mitotic index (MI) in dogs with DLBCL treated with 19 weeks CHOP protocol and correlate them to survival times and clinical stage in order to identify new prognostic factors. Thirty lymphnode samples of dogs diagnosed with DLBCL were evaluated. For immunoexpression of C-MYC, Bcl2 and Ki67, we perform immunohistochemistry using the antibodies C-MYC, Bcl2 (Santa Cruz Biotechnology) and MIB-1 (Dako), respectively. MI was calculated as previously discussed in other tumors. The interpretation of the immunohistochemistry results for C-MYC and Bcl2 was based on the expression level of the area of positive cells, whereas a grid reticle was used for counting Ki67 positive cells in a total area of 1 cm². Cutoff values for all markers were established calculating the mean value and then the C-MYC Bcl2, Ki67 and MI values were classified and defined as “low” and “high”. Cases classified as high C-MYC and high Bcl2, were defined as double target MYC/Bcl2. Mean values were 21 (range: 2,5-53,5) for C-MYC, 32,5 (range: 16,9-76,8) for Bcl2, 107 (range: 1-446) for Ki67 and 21 (range: 0-73) for MI. Only Ki67 immunoexpression was found to be statistical different when survival times were compared between groups low and high (281 days vs 91 days). When double target MYC/Bcl2 was analyzed, no relationship was identified with survival times (p>0,05). Additionally, an association between the antibodies immunoexpression and clinical staging was not identified. However, a positive correlation between C-MYC and Bcl2 (p<0,05) and, Ki67 and MI (P<0,0001) was established. The immunohistochemistry expression of the antibodies C-MYC and Bcl2, individually or in double target, does not appear to constitute a prognostic factor in dogs with DLBCL, whereas a value of Ki67>107 positive cells can be used in dogs with DLBCL to foresee shorter survival times when treated with 19 weeks CHOP protocol.
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Palavras-chave
Apoptose, Imuno-histoquímica, Linfoma multicêntrico, Proliferação celular, Apoptosis, Cellular proliferation, Immunohistochemistry, Multicentric lymphoma