Abstract 5280: A strategic framework for modeling abnormal quiescence that drives cancer evolution, and for preclinical development of therapies to prevent recurrence and metastasis in high-risk patients

Abstract Our goal is to develop a cell culture model of cancer cells that persist under all challenges including therapies, mostly in quiescence, and evolve further to cause recurrence. The rationale for the choice of model as cell culture is that it is ideal of evaluating therapeutic strategies that may inhibit highly abnormal but adaptable cells. Body imposes a variety of bottlenecks ranging from different components of immunity to metabolic challenges to enforce quiescence and influence cancer evolution. As it is not possible to replicate all such bottlenecks in cell culture, our approach is to apply as severe a bottleneck as possible, thus eliminating all proliferative (non-adaptable) cells, leaving behind rare cells surviving in deep quiescence. We hypothesize that if the quiescent cell state being modeled can survive a severe bottleneck, it can also survive other bottlenecks of similar or lower severity. We have arrived at a prolonged lack of glutamine in cell culture medium as a bottleneck for selecting evolutionarily fit rare cells after trying several alternatives, including a lack of glucose, a partial lack of oxygen (hypoxia), or a lack of serum on surface that is unsuitable for cell attachment. While investigating glutamine dependence in aggressive triple-negative breast cancer cell lines, we serendipitously discovered that some rare cells could survive in deep quiescence not only this but variety of other metabolic and therapeutic challenges. Since glutamine and its metabolites are important in protein synthesis, nucleic acid synthesis, epigenome and epitranscriptome regulation, and in maintaining redox status, its sudden disappearance creates a catastrophe killing 99.99% cells; only rare cells survive in deep quiescence and evolve further to proliferate (an important feature of cancer recurrence/metastases). The adaptable cells selected in this manner have many desirable functional and molecular features that are relevant in resistant cancers with an elevated risk of recurrence. We will discuss our observations with rare cells (0.01% in population) surviving in quiescence for several weeks in aggressive breast cancer and melanoma cell lines and their functional characteristics. Our results obtained with adaptable cells from SUM149 TNBC cell line suggest that they are stem-like quiescent cells. Our gene expression analyses and phenotypic changes during quiescence suggest that like a model proposed for stem cell quiescence, cancer stem cells are not dormant; instead, they represent states of poised potential and active restraint as cells “idle” in anticipation of activation, proliferation, and differentiation. We will also discuss how we choose and evaluate therapies that would likely inhibit quiescent and slow-growing cancer cells. This framework may significantly improve anti-cancer drug discovery. Citation Format: Balraj Singh, Anthony Lucci. A strategic framework for modeling abnormal quiescence that drives cancer evolution, and for preclinical development of therapies to prevent recurrence and metastasis in high-risk patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5280.