In vitro models of cell competition: current approaches and future directions.

Cell competition is an evolutionarily conserved quality control mechanism that eliminates less-fit cells to ensure optimal tissue integrity during development, homeostasis, and regeneration. Beyond these physiological roles, recent evidence implicates a role for cell competition in disease, particularly in cancer, where it can function by either suppressing or promoting malignant progression. In this review, we provide an overview of the different molecular mechanisms that drive cell competition and their impact on cancer development and progression. We will evaluate the current state-of-the-art in vitro experimental systems that can be employed to study these processes. Ranging from classical 2D co-culture systems to advanced organoid and organ-on-chip platforms, these model systems collectively enhance our understanding of the complex cellular interactions that underlie the competitive differences between cells. By integrating insights from diverse model systems, we highlight how cell competition shapes tumor dynamics and discuss how this knowledge could inspire novel therapeutic strategies to prevent or control tumor growth.