Gene expression profiling in true interval breast cancer reveals overactivation of mTOR signalling pathway

Background: Interval breast cancers can occur through failure to detect an abnormality at the time of screening (missed interval cancer), or as a new event after a negative screen (true interval cancer). The development and progression of true interval tumors (TIBC) is known to be different than screen-detected tumors (SDBC). However, much work still needs to be done to understand the biological characteristics and clinical behaviour of these TIBC. Objectives: To characterize the gene expression profile in TIBC and SDBC aimed to identify biological markers that may be associated with the emergence of symptomatic breast cancer in the screening interval. Material and Methods: An unsupervised exploratory gene expression profile analysis was performed among 10 samples (discovery set, TIBC=5 and SDBC=5) using Affymetrix Human Gene 1.0 ST arrays and interpreted by Ingenuity Pathway Analysis. Differential expression of selected genes was confirmed in validation series of 91 patients (TIBC=12 and SDBC=79) by immunohistochemistry and 24 patients (TIBC=8 and SDBC=16) by RT-qPCR, expanding the analysis to other genes in same pathway (mTOR, 4E-BP1, eIF-4G and S6).

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Rojo F, Domingo L, Sala M, Zazo S, Chamizo C, Menendez S, Arpi O, Corominas JM, Bragado R, Servitja S, Tusquets I, Nonell L, Macià F, Martínez J, Rovira A, Albanell J, Castells X