Glioblastoma stem cells (GSCs) epigenetic plasticity and interconversion between differentiated non-GSCs and {GSCs}

摘要

Abstract Cancer stem cells (CSCs) or cancer initiating cells (CICs) maintain self-renewal and multilineage differentiation properties of various tumors, as well as the cellular heterogeneity consisting of several subpopulations within tumors. {CSCs} display the malignant phenotype, self-renewal ability, altered genomic stability, specific epigenetic signature, and most of the time can be phenotyped by cell surface markers (e.g., CD133, CD24, and CD44). Numerous studies support the concept that non-stem cancer cells (non-CSCs) are sensitive to cancer therapy while {CSCs} are relatively resistant to treatment. In glioblastoma stem cells (GSCs), there is clonal heterogeneity at the genetic level with distinct tumorigenic potential, and defined {GSC} marker expression resulting from clonal evolution which is likely to influence disease progression and response to treatment. Another level of complexity in glioblastoma multiforme (GBM) tumors is the dynamic equilibrium between {GSCs} and differentiated non-GSCs, and the potential for non-GSCs to revert (dedifferentiate) to {GSCs} due to epigenetic alteration which confers phenotypic plasticity to the tumor cell population. Moreover, exposure of the differentiated {GBM} cells to therapeutic doses of temozolomide (TMZ) or ionizing radiation (IR) increases the {GSC} pool both in?vitro and in?vivo. This review describes various subtypes of GBM, discusses the evolution of {CSC} models and epigenetic plasticity, as well as interconversion between {GSCs} and differentiated non-GSCs, and offers strategies to potentially eliminate GSCs.