Abstract 7376: Modeling the dynamics of lung cancer cells along the epithelial−mesenchymal spectrum in the stem and non-stem cell compartments
Authors: Di Bernardo Arianna , Sahoo Sarthak , Balsamo Melissa , Quaranta Elsa , Jolly Mohit Kumar , Bertolini Giulia , Roz Luca 
Published: March 2024

Abstract
Epithelial-mesenchymal transition (EMT) is a crucial biological process during development which also appears to play a fundamental role in the dissemination of cancer cells. It is known that hybrid states (H), in which cells have mixed epithelial (E) and mesenchymal (M) properties, are particularly conductive to metastasis but the possibility of seeding secondary lesions is also closely linked to the intrinsic tumor initiation potential (stemness). An overall vision taking into account both the EMT spectrum and stemness properties could therefore be the key to fully understanding the metastatic process. In this study we aim to build a mathematical model capable of describing the transitions in the EMT spectrum distinguishing stem from non-stem cell subpopulations in lung cancer cells. Using E-cadherin and N-cadherin staining we evaluated experimentally by flow-cytometry the modulation of epithelial (E), hybrid (H) and mesenchymal (M) phenotypes in A549 lung cancer cells after the induction of EMT by TGFβ treatment and subsequent return to steady state after TGFβ withdrawal. Stem and non-stem populations were identified with the previously validated CD133 marker. To mathematically describe the cellular dynamics we used a system of differential equations assuming transitions E-H, E-M and H-M, for stem and non-stem compartments initially treated as decoupled. Parameters used in the equations were the three switching rates corresponding to the three transitions allowed. To test the robustness of the model we solved the equation multiple times (500) by first stochastically changing the initial conditions and then the initial parameters, obtaining the respective parameters optimized by minimizing the residual between experimental data and model. To decouple the parameters, equations were then solved stochastically 1000 times changing two of three initial parameters, obtaining the optimized third parameter and the respective minimal residual. Parameters fitting closely the experimental data during TGFβ-mediated EMT induction were obtained, indicating that the transition from H to M appears to be absent in the non-stem population but present in the stem population, while the transition from E to M is always present. We also observed that after TGFβ withdrawal the inclusion of an epigenetic decay factor is necessary to model the latency period before MET insurgence when EMT is previously induced in the system. We can conclude that during EMTinduction, the dynamics in the non-stem compartment can be described by a bifurcation model in which population E becomes either M or H and remains permanently in that state, stressing the stability of the H state and also that E cells might have a predisposition to transform into M or H. Furthermore, a portion of H stem cells is able transform into M during EMT and therefore appears more plastic which could underscore a greater metastatic potential.
Citation Format: Arianna Di Bernardo, Sarthak Sahoo, Melissa Balsamo, Elsa Quaranta, Mohit Kumar Jolly, Giulia Bertolini, Luca Roz. Modeling the dynamics of lung cancer cells along the epithelial−mesenchymal spectrum in the stem and non-stem cell compartments [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 7376.