Insights into the quantitative and dynamic aspects of Cell Competition.

Cell Competition (CC) is the process by which viable cells are eliminated from tissues by comparison with neighboring cells (Morata and Ripoll, 1975 [1]) (reviewed in Refs. Madan et al. (2018) [2] and Di Gregorio et al. (2016) [3]). While CC has occasionally been demonstrated in non-epithelial tissues, the vast majority of CC paradigms take place in an epithelial setting, and this will be the object of this review. The majority of studies on CC have been performed in fixed specimens; however, recent studies have analyzed this phenomenon using time-lapse microscopy and computer modelling, which has offered some insight on the cell population dynamics and quantitative aspects of CC. In addition, the ability of CC to modify cell population dynamics critically depends on the type of growth/renewal of the target tissue. In this context, the presence of stem cell compartments and their topology within epithelia, critically constrain the outcome of cell competition. Here we will review the quantitative and dynamic aspects of the cellular interactions that lead to CC and how the renewal modes of epithelial tissues determine the evolution of competing cell populations. We will also provide an overview on how these interactions affect tissue physiology during development, homeostasis, and tumor formation.