DIFFERENTIAL EXPRESSION OF CPB1 IN BREAST CANCER MODELS WITH DIFFERENT LEVELS OF PROGESTERONE RECEPTOR ISOFORMS

FLORENCIA ABASCAL; CLAUDIA LANARI; VICTORIA FABRIS; ANDRES ELIA; PAOLA ROJAS

Congreso; REUNIÓN ANUAL DE SOCIEDADES DE BIOCIENCIA 2019; 2019

Seventy percent of breast cancers are susceptible to an endocrine therapy currently aimed to target the estrogen receptor alpha. We have recently shown that breast cancer tissue cultures with higher levels of progesterone receptor (PR) isoform A (PRA) than isoform B (PRB) were inhibited by the antiprogestin mifepristone. This highlights the relevance of identifying patients that may benefit from this therapy. An RNA-seq study revealed 139 genes that were differentially expressed in 14 patients with higher levels of PRA than PRB (PRA-H) as compared with those with the opposite ratio (PRB-H). In this analysis, we focused in CLEC3A and SCGB1D2 genes upregulated in PRA-H and CPB1 upregulated in the PRB-H tumors. We validated the expression of the three genes using real time PCR (qPCR) using human breast cancer samples and we only found significant values with CPB1. The aim of the study was to further investigate the expression of CPB1 in human and murine breast cancer models with different PR isoform ratios. We used two PRA-H tumors: C4-HD and C4-HI and two PRB-H tumors: C42-HI and C4-HIR from the murine medroxyprogesterone acetate-induced breast cancer model. We evaluated the expression of CPB1 by qPCR and by immunohistochemistry (IHC). CPB1 was upregulated in both PRB-H tumors as compared with the two PRA-H tumors at the mRNA level (qPCR; p