Histone Methyltransferase SETDB1: A Common Denominator of Tumorigenesis with Therapeutic Potential

Epigenetic regulation of gene expression has been ultimately linked to cancer development, with posttranslational histone modifications representing attractive targets for disease monitoring and therapy. Emerging data have demonstrated histone lysine (K) methylation by methyltransferase SETDB1 as a common denominator of gene regulation in several cancer types. SETDB1 reversibly catalyzes the di- and trimethylation of histone 3 (H3) K9 in euchromatic regions of chromosomes, inhibiting gene transcription within these regions and promoting a switch from euchromatic to heterochromatic states. Recent studies have implicated aberrant SETDB1 activity in the development of various types of cancers, including brain, head and neck, lung, breast, gastrointestinal, ovarian, endometrial and prostate cancer, mesothelioma, melanoma, leukemias, and osteosarcoma. Although its role has not been fully elucidated in every case, most data point toward a pro-oncogenic potential of SETDB1 via the downregulation of critical tumor-suppressive genes. Less commonly, however, SETDB1 can also acquire a tumor-suppressive role, depending on cancer type and stage. Here we provide an updated overview of the cellular and molecular effects underlying SETDB1 activity in cancer development and progression along with current targeting strategies in different cancer types, with promising effects either as a standalone therapy or in conjunction with other therapeutic agents.