Abstract LB-050: Memory sequencing reveals heritable single cell gene expression programs associated with therapy resistance

Abstract

Abstract Single cancer cells can have substantial fluctuations in gene expression from non-genetic factors. However, it is unclear how long these fluctuations exist and whether they extend beyond the length of a single-cell division. Current technologies for gene expression measurements in single cells provide just one measurement of each cells’ transcriptome and fail to capture how these gene expression fluctuations change with time. We developed a new method combining Luria and Delbruck's fluctuation analysis with population-based RNA sequencing (MemorySeq) for identifying genes transcriptome-wide whose fluctuations persist for several cell divisions. MemorySeq revealed multiple gene modules that express together in rare cells within otherwise homogeneous clonal populations. Further, we found that these rare cell subpopulations are associated with biologically distinct phenotypes in multiple different cancer cell lines. In melanoma, we identified a rare subpopulation of cells expressing EGFR, NGFR, and AXL, and demonstrated that these cells are resistant to BRAF and MEK inhibitors. In triple-negative breast cancer cells, we identified a different gene expression signature consisting of CA9, and found that this subpopulation is resistant to paclitaxol. We validated these findings in melanoma cell lines by tagging the endogenous locus of MemorySeq gene, NGFR, with a fluorescent protein to directly visualize gene expression fluctuations in individual cells. Broadly, we believe that memory is an essential property of variability that will have phenotypic consequences for cancer cells. Thus, we anticipate that MemorySeq can be extended to uncover the transcriptional states of rare cells driving many phenotypes in cancer including drug resistance, differentiation, invasion, and metastasis. Citation Format: Sydney Shaffer, Benjamin Emert, Eduardo Torre, Arjun Raj. Memory sequencing reveals heritable single cell gene expression programs associated with therapy resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr LB-050.