<b>Estudo da expressão imunoistoquímica de marcadores de resistência a múltiplas drogas em cães com linfoma cutâneo</b>

Abstract

Among mechanisms of resistance are efflux of drugs from intracellular to extracellular through ABC family transporters such as P-glycoprotein, MRP (multple resistance protein) and BCRP (breast cancer resistance protein) and LRP (lung resistance protein), a vault protein responsible for nucleocytoplasmic transport. The aim of this study was to characterize immunophenotypically cutaneous lymphomas, measure cell proliferation using the Ki67 marker, the expression of resistance proteins Pglycoprotein, MRP, BCRP and LRP and to evaluate the relationship of these proteins with the survival of the animals. A retrospective study was performed with 21 cases of dogs with cutaneous lymphoma with histopathological diagnosis.Immunohistochemical was used to immunophenotyping of lymphomas by CD3 and CD20 markers, Ki67 cell proliferation, and P-glycoprotein, MRP, BCRP and LRP expression. Of the 21 animals, 38% had histopathological diagnosis of epitheliotropic lymphoma, 52% were non-epitheliotropic lymphomas, 5% of lymphoma cases had no definition and 5% were classified as round cell neoplasia. The predominant immunophenotype was CD3+CD20-(76%), 15% of the cases were CD3-CD20 + and 9% were CD3 + CD20 +. The median of cells labeled for Ki67 was 31%. Regarding the markers of resistance to multiple drugs, the median of the P-glycoprotein label was 40%, which 65% of LRP while for MRP and BCRP, 19% and 23%, respectively. Non-epitheliotropic cutaneous lymphomas were more frequent than epitheliotropic lymphomas and the predominant immunophenotype was T. The occurrence of CD3-CD20+ and CD3+CD20+ lymphocytes indicates the need for further studies and a wider panel of antibodies for subtyping these lymphomas. P-glycoprotein had higher expression in non-epitheliotropic lymphomas than in epitheliotropic lymphomas and there was no correlation between resistance proteins and survival time of the animals, suggesting that in addition to the biology of neoplasia other mechanisms of resistance to multiple drugs different from those studied may play a relevant role in the low response of cutaneous lymphoma to chemotherapy.