Single-Cell Mrna Profiling Reveal Transcriptional Heterogeneity Among Pancreatic Circulating Tumor Cells

Background: Single-cell analysis of the transcriptional heterogeneity of circulating tumor cells have the prospect of better understanding the biology of these cells and their involvement in the metastatic process. In addition, such analyses may reveal new knowledge about the mechanisms leading to chemotherapy resistance and tumor progression in pancreatic cancer patients. Methods: Single circulating tumor cells were enriched from blood samples (n = 50) from patients with advanced pancreatic cancer using our previously established negative depletion strategy MINDEC, and detected by immuno-fluorescence microscopy. The single cells were isolated by micromanipulation, reverse transcribed, pre-amplified, and analyzed using single cell multiplex mRNA profiling to reveal transcriptional heterogeneity. Results: Circulating tumor cells were detected in 29 (58%) of the examined blood samples. A total of 48 potential circulating tumor cells were isolated, in which 17 cells had detectable mRNA levels and were identified as circulating tumor cells by expression of epithelial (KRT8, KRT19, EPCAM, E-Cadherin) or mesenchymal (Vimentin, N-Cadherin, ZEB1) markers. These pancreatic circulating tumor cells were revealed to heterogeneously express the examined transcripts, and also showed aberrant expression of cancer stem cell (CD24, CD44, ALDH1A1) markers and the extracellular matrix marker SPARC. Hierarchical clustering and principal component analyses revealed epithelial-like and mesenchymal-like circulating tumor cell subpopulations, which were distinct from white blood cells and cancer cell line cells. Further analyses of the transcript SPARC suggested a relation to epithelial-mesenchymal transition in pancreatic circulating tumor cells. Conclusion: The analysis of single pancreatic circulating tumor cells defines distinct subpopulations and reveals aberrant expression of transcripts relevant for the dissemination of circulating tumor cells to distant sites. Citation Format: Morten Lapin, Kjersti Tjensvoll, Satu Oltedal, Milind Javle, Rune Smaaland, Bjornar Gilje, Oddmund Nordgard. Single-cell mRNA profiling reveal transcriptional heterogeneity among pancreatic circulating tumor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-252. doi:10.1158/1538-7445.AM2017-LB-252