Acquisition of Letrozole Resistance Through Activation of the p38/MAPK Signaling Cascade.

Background/aim: Previous reports identified a global proteomic signature of estrogen-independent letrozole resistant breast cancer cells, however, it remains unclear how letrozole-resistance is impacted when cells remain estrogen receptor positive (ER+).

Materials And Methods: To capture the protein expression profile associated with ER+ Aromatase inhibitor (AI) resistance, a global proteomic analysis was conducted using the letrozole-sensitive (T47Darom cells) and letrozole-resistant cells (T47DaromLR cells). To examine the molecular features associated with this phenotype Kaplan- Meier analysis, phospho-antibody arrays, proliferation and apoptosis assays were conducted.