Locally disordered methylation forms the basis of intratumor methylome variation in chronic lymphocytic leukemia
Landau, D.A., Clement, K., Ziller, M.J. et al.
Intratumoral heterogeneity plays a critical role in tumor evolution. To define the contribution of DNA methylation to heterogeneity within tumors, we performed genome-scale bisulfite sequencing of 104 primary chronic lymphocytic leukemias (CLL). Compared to 26 normal B cell samples, CLLs consistently displayed higher intra-sample variability of DNA methylation patterns across the genome, which appears to arise from stochastically disordered methylation in malignant cells. Transcriptome analysis of bulk and single CLL cells revealed that methylation disorder was linked to low-level expression. Disordered methylation was further associated with adverse clinical outcome. We therefore propose that disordered methylation plays a similar role to genetic instability, enhancing the ability of cancer cells to search for superior evolutionary trajectories.
Landau, D.A., Clement, K., Ziller, M.J. et al. "Locally disordered methylation forms the basis of intratumor methylome variation in chronic lymphocytic leukemia" Cancer Cell (2014): 813–25