Immunologic markers associated with favorable prognosis in breast cancer patients: Role of innate immune system.

Abstract

43 Background: Recognition of tumor cells by NK cells is mediated by the interaction of activating and inhibitory NK cell receptors with ligands expressed on the interacting cell. In addition to inhibitory and activating receptors, NK cells express adhesion molecules that allow conjugate formation between NK cells and their tumor targets. We have recently identified by transcriptional analysis of breast tumor specimens a signature of 5 genes, which included B cell response and interferon signaling, found to predict with > 85% accuracy relapse-free survival. In the current study we analyzed by gene expression profile, whether a differential expression of activatory and inhibitory receptors and gene involved in NK cell-target interactions could be identified in relapse and relapse free patients.Methods: RNA extraction and gene expression analysis was performed on tumor specimens with at least 10% of infiltrating cells deriving from 9 from breast cancer patients who had either 3-7 years relapse-free survival (n=9) or developed tumor relapse within 1-3 years after the initial treatment (n=8). Data were analyzed by BRB tools and Partek software.Results: Our results showed that patients with a favorable prognosis showed increased expression of genes involved in NK interaction with tumor cells and NK activating signaling. In particular an up-regulation of leukocyte function-associated antigen 1 (LFA-1) gene, typically involved in NK cells adhesion to target cells and DNAM 1, usually associated with activation of NK cells and considered one of the major protagonist of NK- Dendritic cells crosstalk, was observed to occur in relapse free patients. In addition, an up regulation of CD96 and CRTAM which, like DNAM 1, promote NK cell-target cell adhesion by interacting with the Necl2 and poliovirus receptor (PVR), was observed in relapse free patients. Conclusions: Our observation suggests that the NK signatures are associated with favorable outcome in breast cancer and allow us to generate new hypothesis on the role of innate immunity in this contest.