Role of histone lysine methyltransferases SUV39H1 and SETDB1 in gliomagenesis: Modulation of cell proliferation, migration, and colony formation

Posttranslational modifications of histones are considered as critical regulators of gene expression, playing significant role in the pathogenesis and progression of tumors. Trimethylation of histone 3 lysine 9 (H3K9me3), a repressed transcription mark, is mainly regulated by the histone lysine N-methyltransferases (HKMTs), SUV39H1 and SETDB1. The present study investigated the implication of these HKMTs in glioma progression. SUV39H1 and SETDB1 expression was upregulated in glioma cell lines (GOS-3, 1321N1, T98G, U87MG) and in glioma tissues compared to normal brain being positively correlated with grade and histological malignancy. Suppression by siRNA of the two HKMTs for 24 and 48 h resulted in significantly reduced proliferation of GOS-3 and T98G glioma cells with siSUV39H1 effects been most prominent. Furthermore, HKMTs knockdown-induced apoptosis with a high rate of apoptotic cells have been observed after siSUV39H1 and siSETDB1 for both cell lines. Additionally, suppression of the two HKMTs reduced cell migration and clonogenic ability of both glioma cell lines. Our results indicate overexpression of SETDB1 and SUV39H1 in gliomas. Treatments that alter HKMT expression affect the proliferative and apoptotic rates in glioma cells as well as their migratory and colony formation capacity. These data suggest that both HKMTs and especially SUV39H1 may serve as novel biomarkers for future therapeutic targeting of these tumors.