Activation of IFN/STAT1 signaling is a hallmark of response to chemotherapy in patient-derived xenografts of triple-negative breast cancer

By using patient-derived xenografts (PDXs) as living surrogate of the clinical practice, we identify here induction of genes related to the IFN pathway as an early and specific predictor of tumor response to treatment. Gene expression profile of tumor cells after laser-capture microdissection of residual tumor foci to characterize the molecular changes occurring in residual tumor cells surviving chemotherapy RNA was extracted from microdissected areas using the RNeasy Mini kit (Qiagen, Valencia, CA). This approach allowed isolating foci of human tumor cells from the murine stroma. Gene expression analysis was performed with Affymetrix Exon 1.0 ST microarrays. Hybridization, data normalization and statistical analysis were outsourced to GenoSplice Technology (Paris, France).