CD4+, CD8+, FoxP3+ and HSP60+ Expressions in Cellular Infiltrate of Canine Mammary Carcinoma in Mixed Tumor

Abstract

Background: Cancer is a complex process that receive many influences of the tumor microenvironment. The participation of immune system cells and proteins in tumor microenvironment is not yet completely understood. Thus, the aim of this study was to evaluate the infiltrate cellular, subpopulations of T-lymphocytes and HSP60 of canine mammary carcinoma in mixed tumor (CMCMT).

Materials, Methods & Results: Female dogs (n = 20) were selected after Canine mammary tumor (CMT) diagnosis and data were achieved throughout clinical-pathological information. Clinical staging was evaluated and tumor biopsies were processed by histology and cellular infiltrate was performed according criteria and grade. Survival curve were generated by Kaplan-Meier and the lymphocytic infiltrate were compared by Log-Rank followed Chi-Square χ². For immunolabeling it was used anti-CD4, anti-CD8, anti-FoxP3 and HSP60 monoclonal antibodies and were attributed scores from 0 to 3. Clinical-pathological relationship was analyzed using Spearman correlation. This study was approved by the Committee for Ethics in Research using Animals (CEUA-UECE), protocol 12247080-2. Our data showed a mean age of 9.3 years-old, the size of tumors presented more than 5 cm (50%), which were located in inguinal mammary glands (70%), and CMTs shows I (70%) and II (30%) grade. The cellular infiltrate was distributed both in peri and intratumoral regions, dispersed multifocally with moderate intensity and lymphocytes were the major populations found into tumors (n = 826 ± 220). In relationship to cellular infiltrate with CMT grade it was observed that lymphocytes (ρ = 0.28) and plasma cells (ρ = 0.22) showed a slight positive correlation, and an opposed negative correlation of neutrophils (ρ = -0.1) and macrophages (ρ = -0.38). CMT presents moderate lymphocytic infiltrate (< 800 lymphocytes), shows higher (P = 0.01) survival rates as compared to intense lymphocytic infiltrate (≥ 800 lymphocytes). FoxP3+ showed lower intensity while CD4+ and CD8+ expression were concentrated surrounding of lymphocytic infiltrate tumor region. HSP60+ was observed in the inflammatory and tumor cells.

Discussion: Our data are according to a greater risk to the development of breast tumor in old bitches, not castrated and before or after puberty, as well as the use of contraceptives based on progesterone and estrogen. In relation to size of tumor, these findings reinforce that there is a relationship of tumor size with a higher malignancy grade and with a worse prognosis. The predominant tumor location was in the inguinal breasts that is attributed to the high activity of the mammary glands to hormonal stimuli. CMT with low clinical staging are associated with greater overall survival of affected bitches. In relation to tumor microenvironment, it has been reported that heterogeneous populations of the immune system cells often infiltrate the mammary tumors, whose lymphocytes are the main cells. It is suggested that tumor lymphocytosis may be necessary for malignant behavior of the tumor microenvironment. On the other hand, macrophages and neutrophils play an important role that may favor or inhibit the tumor cells development in the tumor microenvironment. In our work, CD4, CD8 and FoxP3 labeling were distributed in peri and intratumoral regions, and consequently, these markers can be used as prognostic for CMT, as well as being a potential target for anticancer therapies. This is the first work that presents results about the participation of HSP60 in CMT, however this data needs further investigation. HSP60 participates as a potent activator of the immune system through its peptides and other HSP types were studied in mammary carcinomas in bitches and presenting results that indicate the association of these proteins with the carcinogenesis process.