EXPRESSION AND SUBCELLULAR LOCALIZATION OF P73 AS PROGNOSIS IN BREAST CANCER SUBTYPES

GOMEZ, LAURA C; SOTTILE, MAYRA L; REDONDO, ANALIA L; MARZESE, DIEGO M; VARGAS-ROIG, LAURA M

San Luis

Congreso; XXXVII Reunión Científica Anual Sociedad de Biología de Cuyo; 2019

The incidence of breastcancer (BC) is high in Argentina. The optimal treatment is based on proteomicand histological prognostic factors. Based on variations in gene expression, BCpatients are currently classified into five major subtypes: luminal A, luminalB, ErbB2+, basal-like and normal-like. We previously reported that themethylation of TP73 differed significantly between molecular subtypes. LuminalA tumours frequently exhibited unmethylated TP73; in contrast, all basal-liketumours exhibited methylated TP73. The P73 protein has numerous isoforms withdifferent biological and antagonistic functions. The goals of our study were todetermine the expression and subcellular localization of the P73 isoforms, itsrelationship with TP73 methylation and their clinical prognostic significancein BC subtypes. For this, we evaluated the expression and subcellularlocalization of TA-p73 and ΔNp73 isoforms in 137 invasive breast tumors and 3 BC cell lines byimmunohistochemistry and immunofluorescence, respectively. The results showed an exclusive nuclear localization of TA-p73 isoformin 88.9% of luminal BC tumors expressing this isoform. In contrast, basal-like and ErbB2+ tumors mainly exhibited cytoplasmaticexpression of TA-p73 isoform in 69,9% and 72%, respectively. The ∆Np73 isoform was mainly expressed incytoplasm of all breast tumors with different molecular subtypes. Concomitant,TA-p73 isoform was localized almost exclusively at the nucleus of luminal BC celllines, while it was mainly expressed in cytoplasm of basal-like cell line. Alltogether our data suggest that expression and subcellular localization of p73isoforms are useful factors as prognosis in breast cancer subtypes.