EXPRESSION OF FOXP3 TRANSCRIPTION FACTOR IN TUMOR SAMPLES AND PERIPHERAL BLOOD MONONUCLEAR CELLS FROM BREAST CANCER PATIENTS

CANZONERI R; LACUNZA E; BERMAN C; MELCHIORI P; CRETÓN A; RABASSA ME; CROCE MV; ISLA LARRAIN M

Jornada; XXXV Jornadas Multidisciplinarias de Oncología; 2022

Introducción y antecedentes: Breast cancer constitutes a heterogeneous group of malig-nant neoplasms with high incidence and mortality rates. The study of the immune responseand tumor evasion mechanisms are relevant to identify new prognostic biomarkers and thera-peutic targets. The combination of immunotherapy agents with conventional therapies showspromising results in cancer treatment. For this reason, clinical trials combining various immuno-logical checkpoint inhibitors are in progress in breast cancer and other tumor locations.Objetivos: To study the expression of Foxp3 in tumor microenvironment and peripheralblood mononuclear cells in breast cancer in order to evaluate the relevance of this transcrip-tion factor in tumor biology and ts potential role as a therapeutic target.Materiales y Métodos: Tumor and peripheral blood samples from 127 breast cancer (BC)patients without treatment were obtained during surgery at the Hospital Itallano de La Plata(Argentina) with informed consent. The expression of Foxp3, CD45RO and CD8 was studiedby IHC in histopathological sections of tumor samples. ER, PR and HER2-neu receptorsexpression was also evaluated. The expression of FOXP3 mRNA in peripheral blood mononu-clear cells (PMBO), isolated through Ficol-Hypaque gradient, was evaluated by PCR. Univariateand Kendall statistical correlation analysis were performed in SPS5 program. Besides, a bioinfor-matic analysis of the expression of FOXP3 and co-expressed genes was carried out, on RNA-—Seg data (PANCANCER_TCGA, n = 1084) and RNA microarrays (G5£21653, n = 266), consi-dering the intrinsic subtypes of breast cancer.Resultados: Foxp3 was found in 61% of BC samples, showing a positive correlation withCD8+ cells and a negative association with tumor stage. In 73.5% PBMC samples, FOXP3expression was found showing a positive association with advanced tumor stages and PR(p