unc-0638 and Breast-Neoplasms

There is currently a growing interest in the roles of epigenetic mechanisms in the diagnosis, prognosis, and therapies associated with precision oncology for breast cancer (BC). This study aimed to demonstrate the clinical significance of euchromatic histone lysine methyltransferase 2 (EHMT2), histone deacetylase 1 (HDAC1) and HDAC2 in BC, to evaluate the antitumor effectiveness of a combination of the selective inhibitors UNC0638 and CI-994 (U+C), and to clarify the underlying mechanisms.. Multi-omic analysis was used to study the clinical significance of the biomarkers of interest. The effects of U+C treatment were evaluated by detecting cell viability, cell cycle, apoptosis, and representative gene expressions. RNA-Seq and Gene Set Enrichment Analysis (GSEA) were employed to identify over-represented genes associated with the treatment. Chromatin immunoprecipitation and qPCR (ChIP-qPCR) assay were applied to verify epigenetic profiling on the identified promoters.. The significance of elevated expressions of EHMT2, HDAC1, and HDAC2 in tumor tissue and BC basal-like subtype in predicting a poor prognosis was noted. The U+C combined treatment showed an enhanced suppressive effect as compared to single agent treatment, perturbed the cell cycle, induced apoptosis, reduced expressions of the genes representing anti-apoptosis, stemness, drug resistance and basal-like state, while increasing luminal-like state genes. In addition, the combined U+C treatment suppressed xenograft tumor growth. The epigenetic reprogramming of histones was identified in the down-regulated BIRC5 and upregulated GADD45A.. These findings demonstrate that selectively targeting EHMT2, HDAC1, and HDAC2 by concurrent U+C treatment suppresses BC tumor progression via epigenetic remodeling of BIRC5 and GADD45A.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Benzamides; Breast Neoplasms; Cell Cycle Proteins; Cell Line, Tumor; Disease Progression; Epigenesis, Genetic; Female; Gene Expression Regulation, Neoplastic; Humans; MCF-7 Cells; Mice, Inbred NOD; Mice, SCID; Phenylenediamines; Quinazolines; Survivin; Xenograft Model Antitumor Assays

Protein lysine methyltransferase G9a plays key roles in the transcriptional repression of a variety of genes via dimethylation of lysine 9 on histone H3 (H3K9me2) of chromatin as well as dimethylation of nonhistone proteins including tumor suppressor p53. We previously reported the discovery of UNC0321 (3), the most potent G9a inhibitor to date, via structure-based design and structure-activity relationship (SAR) exploration of the quinazoline scaffold represented by BIX01294 (1). Despite its very high in vitro potency, compound 3 lacks sufficient cellular potency. The design and synthesis of several generations of new analogues aimed at improving cell membrane permeability while maintaining high in vitro potency resulted in the discovery of a number of novel G9a inhibitors such as UNC0646 (6) and UNC0631 (7) with excellent potency in a variety of cell lines and excellent separation of functional potency versus cell toxicity. The design, synthesis, and cellular SAR of these potent G9a inhibitors are described.

Topics: Blotting, Western; Breast Neoplasms; Cell Proliferation; Colonic Neoplasms; Enzyme Inhibitors; Female; Histocompatibility Antigens; Histone-Lysine N-Methyltransferase; Humans; Male; Models, Molecular; Prostatic Neoplasms; Protein Binding; Protein Conformation; Quinazolines; Structure-Activity Relationship; Tumor Cells, Cultured