Abstract IA22: Investigating breast cancer evolution and diversity with single-cell sequencing

Abstract

Abstract Sequencing breast tumor cohorts has identified many prevalent mutations, but provides limited insight into the genomic diversity within tumors. Here, we developed a whole-genome and exome single-cell sequencing approach called Nuc-Seq that can achieve 83-97% coverage breadth with low error rates. We applied this method to sequence single normal and tumor cells from an estrogen-receptor positive breast cancer and a triple-negative ductal carcinoma, and performed copy number profiling in parallel. Our data shows that aneuploid rearrangements occurred early in tumor evolution and remained highly stable as the tumor masses expanded. In contrast, point mutations evolved gradually, generating extensive clonal diversity. Many of the diverse mutations were shown to occur at low frequencies (0.03 -10%) in the tumor mass by targeted single-molecule sequencing. Using mathematical modeling we found that the triple-negative tumor cells had an increased mutation rate (13.3X) while the ER+ tumor cells did not. These findings have important implications for the diagnosis, therapeutic treatment and evolution of chemoresistance in breast cancer. Citation Format: Nicholas E. Navin. Investigating breast cancer evolution and diversity with single-cell sequencing. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr IA22.