Establishment of Monoclonal Cell Subpopulations as Model Systems for Functionally Exploring Resistance Mechanisms in EGFR Mutant Non-Small Cell Lung Cancer

Understanding the molecular events that drive tumor evolution remains a high priority for understanding dynamic response to anti-cancer targeted treatment. However, model systems that allow to dissect individual clones’ activity in heterogenous tumors are still limited in cancer research. To fill this gap, we established monoclonal cell populations (MCP) from a commercial cell line and used this model system to identify coexisting cellular and molecular events that drive response to targeted treatment within an individual lesion. MCPs were established from the H1975 EGFR-mutant NSCLC cell line using single cell cloning and expansion techniques. Of the 120 single cells seeded, 25 expanded successfully. Cell morphology, baseline signaling network, and response to anti-EGFR treatment was compared across the clones and the parental cell line. MCP established from the same cell line had unique morphological features and 58% of clones had a different morphology compared to the parental cell line. No direct correlation was observed between rate of expansion and cell morphology. Sensitivity to anti-EGFR treatment varied significantly across different clones and compared to the parental line from which they were established. Signaling profile of coexisting MCPs had distinct characteristics based on their level of susceptibility to anti-EGFR treatment. Our study suggest that monoclonal cell subpopulations may represent a useful model system for understanding the interplay between different cell subpopulations in heterogenous tumors. Defining molecular profiles of coexisting monoclonal cell subpopulations may lead to the identification of biomarkers that can assist physicians in predicting response to treatment or design combination regimens that concomitantly target different subclones within the tumor microecology.