Differential EGFR and VEGFR mRNA expression in two subtypes of basal-like breast cancer identified by molecular classification

Abstract

22092 Background: Molecular classification based on only four genes [estrogen receptors (ER), progesterone receptors (PgR), HER2, and melanophilin (MLPH)] identifies two distinct basal-like subtypes in high-risk breast cancer patients, associated with poor prognosis. The objective of the present study was to investigate possible differential EGF and VEGF receptor mRNA expression in the two basal-like subtypes. Methods: Patients were treated with adjuvant anthracycline-based dose-dense sequential chemotherapy (E-CMF vs. E-T-CMF) in the context of a randomized Phase III study. RNA was isolated from 217 fixed tumor tissue samples, followed by kinetic one-step RT- PCR for mRNA expression analysis of EGFR, VEGFR2 and VEGFR3. Identification of the basal-like subtypes was based on 2D hierarchical clustering. Results: One of the basal-like subtypes (14 of 217 patients, 6%, group A) was found to retain some expression of the HER2, ER and MLPH genes. The second basal-like subtype (18 of 217 patients, 8%, group B) w...