Tumor cells display phenotypic plasticity and heterogeneity due to genetic and epigenetic variations which limit the predictability of therapeutic interventions. Chromatin modifications can arise stochas- tically but ...Tumor cells display phenotypic plasticity and heterogeneity due to genetic and epigenetic variations which limit the predictability of therapeutic interventions. Chromatin modifications can arise stochas- tically but can also be a consequence of environmental influences such as the microenvironment of cancer cells. A better understanding of the impact and dynamics of epigenetic modulation at defined chromosomal sites is required to get access to the underlying mechanisms. We investigated the epige- netic modulations leading to cell-to-cell heterogeneity in a tumor cell line model. To this end, we analyzed expression variance in 80 genetically uniform cell populations having a single-copy reporter randomly integrated in the genorne. Single-cell analysis showed high intraclonal heterogeneity. Epige- netic characterization revealed that expression heterogeneity was accompanied by differential histone marks whereas contribution of DNA methylation could be excluded. Strikingly, some clones revealed a highly dynamic, stochastically altered chromatin state of the transgene cassette which was accompanied with a metastable expression pattern. In contrast, other clones represented a robust chromatin state of the transgene cassette with a stable expression pattern. Together, these results elucidate locus-specific epigenetic modulation in gene expression that contributes to phenotypic heterogeneity of cells and might account for cellular plasticity.展开更多
基金supported by the Initiating and Networking Fund(IVF)of the Helmholtz Association within the Helmholtz Initiative on Synthetic Biology(No.SO-078)the Federal Ministry of Education and Research(BMBF)for the EBio project CellSys FKZ(No.031 6189 B)+1 种基金Financial support was also obtained from the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)(Cluster of Excellence REBIRTH as well as the project No.WI2648/31)the support by the HZI GradSchool
文摘Tumor cells display phenotypic plasticity and heterogeneity due to genetic and epigenetic variations which limit the predictability of therapeutic interventions. Chromatin modifications can arise stochas- tically but can also be a consequence of environmental influences such as the microenvironment of cancer cells. A better understanding of the impact and dynamics of epigenetic modulation at defined chromosomal sites is required to get access to the underlying mechanisms. We investigated the epige- netic modulations leading to cell-to-cell heterogeneity in a tumor cell line model. To this end, we analyzed expression variance in 80 genetically uniform cell populations having a single-copy reporter randomly integrated in the genorne. Single-cell analysis showed high intraclonal heterogeneity. Epige- netic characterization revealed that expression heterogeneity was accompanied by differential histone marks whereas contribution of DNA methylation could be excluded. Strikingly, some clones revealed a highly dynamic, stochastically altered chromatin state of the transgene cassette which was accompanied with a metastable expression pattern. In contrast, other clones represented a robust chromatin state of the transgene cassette with a stable expression pattern. Together, these results elucidate locus-specific epigenetic modulation in gene expression that contributes to phenotypic heterogeneity of cells and might account for cellular plasticity.
