Abstract 1853: Single-cell multiplexed profiling of protein-level changes induced by EGFR inhibitor gefitinib

Abstract

Abstract Single-cell molecular analysis has become increasingly important in biomedical research, especially in the field of cancer research, where cell heterogeneity is a characteristic feature. We developed a multiplexed single-cell protein detection assay for the C1™ system that can isolate and process 96 individual cells in parallel. The assay uses oligonucleotide-conjugated antibodies, which produce a detectable DNA amplicon only when they bind to the target protein. The resulting DNA amplicons are quantified by qPCR on the Biomark™ HD system. Data are analyzed using the Singular™ Analysis Toolset. A total of 50 antibody binders were developed for this assay to target proteins related to apoptosis, cell cycle, cell proliferation, tumor suppressors, biomarkers, stem cells, growth factors and proteins associated with specific cancers, such as breast and prostate cancers. The assay can be performed in a 48-plex format, which yields over 4,600 datapoints in two days. Assay sensitivity and specificity were assessed using recombinant proteins and various cell lysates. To demonstrate the usefulness of this assay, we used it to profile the protein level changes in A431 cells treated with epidermal growth factor receptor (EGFR) inhibitor gefitinib. EGFR is a member of ErbB family of type I tyrosine kinases, whose overexpression and mutations are involved in a variety of cancers. While much effort has been made to investigate the consequences of EGFR activation or inhibition, hardly any information is available regarding how EGFR regulation changes protein expression in single cells. Using a multiplexed protein assay, we discovered some interesting co-expression patterns of proteins in single cells. We also demonstrated that TNFRSF10B was upregulated, while MET, GATA3, BRCA1, CCNB1, Ki-67 and CCNA2 were downregulated by gefitinib treatment. Notably, the reduction of the cell cycle-related proteins CCNB1 and CCNA2 and the cell proliferation marker Ki-67 was consistent with the inhibited cell growth by gefitinib. In addition, we measured mRNA expression to investigate the association between protein and mRNA levels in single cells. Single-cell analysis—determining protein changes and analyzing the correlation between different proteins at the single-cell level—yields valuable information that is not achievable using bulk-cell analysis. Citation Format: Ilona Holcomb, Gajalakshmi Dakshinamoorthy, Benjamin Liu, Marc Unger, Ramesh Ramakrishnan, Haibiao Gong. Single-cell multiplexed profiling of protein-level changes induced by EGFR inhibitor gefitinib. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1853.