Lineage-resolved lifetime modelling reveals potential quiescence and synchronization among MDA-MB-468 breast cancer cells.

This study presents evidence of a previously unrecognised structured organisation of untreated cancer cell lineages and suggests an unexpected sensitivity to subtle experimental perturbations that is not readily explained by standard population models. These conclusions are based on exploratory analyses of cell-tracking data from untreated MDA-MB-468 breast cancer cells cultured under standard conditions. The analyses indicate that lineage-tracking data can reveal multiple layers of heterogeneity, synchronisation, and ancestry, together with stable quiescent, senescence-like, or persister-like states, even in the absence of external perturbation. These findings are hypothesis-generating rather than confirmatory and are intended to motivate future studies designed to test these hypotheses. The analysis is based on 72-h recordings from one or two wells in each of 21 independent experiments, comprising trajectories of 4,000 initial cells and their 34,152 descendants. During observation, 238 (6%) of the initial cells died, whereas 39 (1%) survived without dividing. The lifetimes of initial cells that died are well described by a conventional mixed gamma distribution, but the observed number of non-dividing survivors exceeds model predictions, suggesting a subpopulation with prolonged quiescent or senescence-like behaviour. The study further explores information extracted from healthy pedigree trees, defined by three consecutive normal cell divisions from the start of recording and no subsequent cell death. Only 22% of the 4,000 pedigree trees satisfy these criteria; the remainder exhibit abnormal divisions, prolonged intermitotic times, or cell death. Basic renewal theory indicates that initial cells tend to delay their first division, consistent with systematic differences between first- and second-generation intermitotic times. Finally, comparisons of pooled and experiment-specific lifetime distributions identify information-theoretic "elements of surprise". Unexpectedly pronounced local maxima in empirical probability densities suggest high sensitivity to experimental conditions and may also reflect cellular synchronisation through intercellular communication together with ancestry-dependent inheritance.