Spontaneous differentiation leads to emergence of hybrid cell states relate to poor prognosis in oral cancer

Abstract

Cancer cells within individual tumors often exist in distinct phenotypic states contributing to intratumoral heterogeneity (ITH). However, studies on cell state dynamics among oral cancer cells are largely missing. Here, we have multiplexed phenotypic markers of putative oral-stem-like cancer cells (SLCCs) and characterized diversity among CD44-positive oral cancer cell subpopulations with respect to distinct expression of CD24 and aldehyde dehydrogenase (ALDH)-activity. Our in vitro experimental observations were explained by a Markov model where subpopulations followed two distinct patterns of spontaneous repopulation dynamics. Cells showed stochastic inter-conversions on ALDH-axis, harnessed by cancer cells to enrich ALDHHigh subpopulations in response to Cisplatin treatment. However, these cells followed a strict non-interconvertible transition of CD24Low to CD24High subpopulations, even in response to chemotherapy-induced stress. Using phenotype-specific RNAseq, we suggest the organization of subpopulations into hierarchical structure with possible maintenance of intermediate alternate states of stemness within the differentiating oral cancer cells. We also show that the population dynamics described here may influence tumor behaviour by increasing ITH in aggressive oral tumors. Overall, the described phenotypic subgroups not only reliably exhibited spontaneous or Cisplatin-driven cellular dynamics but also the distinct transcription states of oral cancer cells. Most importantly, our in vitro model system derived observations emphasized the prognostic power which may be translated for betterment of oral cancer patients.Graphical AbstractWe have characterized diversity among CD44-positive oral cancer cells lines with respect to distinct expression of CD24 and ALDH-activity. Cells showed stochastic inter-conversions on ALDH-axis but a strict non-interconvertible transition of CD24Low to CD24High phenotype, even in response to chemotherapy-induced stress. RNAseq study suggested the organization of subpopulations into hierarchical structure with possible maintenance of intermediate alternate states of stemness within the differentiating oral cancer cells. The described population dynamics may influence tumor behaviour by increasing intratumoral heterogeneity in aggressive oral tumors.