Abstract 3704: Whole genome and targeted proteome analysis of single cancer cells

Abstract

Abstract The simultaneous genome and proteome analysis of very rare single cells would enable addressing important biological and diagnostic questions particularly in cancer. Here, we introduce a novel genome and proteome (G&P) analytic workflow, a method allowing comprehensive analysis of single-cell DNA and targeted profiling of protein expression in single cells. As a proof of concept, we demonstrate the capability of the method by quantifying copy number of the ERBB2 gene alongside with protein expression levels of HER2 and phospho-HER2 in single cells. The G&P workflow utilizes antibodies conjugated with DNA oligonucleotides designed to enable their amplification alongside the single-cell genome facilitating parallel genome and proteome profiling by either quantitative PCR (qPCR) or sequencing. We utilized antibodies targeting cytokeratin 8/18/19, HER2 and phospho-HER (Tyr1248). Performance of each DNA-conjugated antibody was assessed by immunofluorescence staining in a variety of breast cancer cell lines (MDA-MB231, MDA-MB453, BT474 and MCF7) and sample types. Stained cells were isolated by manual micromanipulation and subjected to whole genome amplification (WGA). Protein expression levels, derived from quantification of the amplified DNA tags, were measured by qPCR. Shallow whole genome sequencing was employed to facilitate genome-wide profiling of copy number variations (CNVs), including the ERBB2 locus. We successfully developed and tested a G&P workflow allowing parallel genome-wide CNV profiling and quantification of three target proteins. G&P measurement yielded concordant results to immunofluorescence quantification for all tested markers. Furthermore, the workflow allowed direct correlation of copy numbers of the ERBB2 gene with HER2 expression in single cancer cells. Notably, the method enabled measurements of cellular and molecular responses at the single-cell level to lapatinib treatment, i.e. monitoring of the HER2 pathway activation level. Our novel multiplex G&P technique is capable of generating multiparametric measurements linking DNA copy numbers and expression levels of selected genes of interest. The method is optimized for analysis of single cells from rare cell populations and is readily translatable to study circulating tumor cells (CTCs) and disseminated cancer cells (DCCs), enabling for the first time pathway analysis via phosphoprotein analyses of these cells. Citation Format: Atieh Alyasin, Kathrin Weidele, Catherine Botteron, Christoph A. Klein, Zbigniew T. Czyż. Whole genome and targeted proteome analysis of single cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3704.