A novel prognostic signature based on centrosome amplification-based genes to predict clinical outcomes in breast tumors.

Abstract

11604 Background: A majority of breast tumors exhibit centrosome amplification (CA), which imparts aggressive phenotypes like chromosomal instability and invasive behavior. Nevertheless, it is unclear whether CA is associated with poor clinical outcomes after adjusting for potentially confounding factors, like stage and age at diagnosis. Methods: We developed a twenty-gene signature, “CA20,” composed of genes related to centrosome structure and/or whose dysregulation induces CA and tested its prognostic value compared with that of CIN25, a chromosomal instability (CIN) signature, in combined multivariable Cox models using the METABRIC and TCGA microarray breast datasets. The n = 1,969 primary breast cancers of the METABRIC dataset were split randomly and approximately equally into training and validation sets, unlike the n = 524 primary invasive breast cancers of the TCGA dataset, which could not be split to preserve power ≈ 0.80, so bootstrapping was instead used. CA20 and CIN25 were dichotomized by average scores and optimal cutpoints based on the log-rank test. Results: In both discovery and validation METRABRIC sets, CA20 was a significant independent predictor of worse breast cancer-specific survival (HR = 2.9, p < 0.001 and 2.4, p < 0.001, respectively, using average scores as cutpoints; similar results obtained using optimal cutpoints) in multivariable Cox models, unlike CIN25. CA20 score was highly correlated with CIN25 score (ρ = 0.93, p < 10-6). In the TCGA dataset, high CA20 score was associated with 3.8- and 3.7-fold worse overall survival (bootstrap-p = 0.001 and 0.002, respectively, for average and optimal cutpoints) after adjusting for tumor stage and age at diagnosis, unlike CIN25. Also in the TCGA dataset, CA20 correlated very strongly with CIN25 (ρ = 0.95, p < 10-6). Finally, using the TCGA dataset, we identified processes and pathways enriched in the CA20-high group (q < 0.05) that may be potential therapeutic targets, such as DNA repair processes, the DNA integrity checkpoint, and regulation of microtubule dynamics. Conclusions: CA20 is a novel signature with robust prognostic value in breast cancer and identifies patients who might respond to centrosome declustering drugs.