Anticancer drug mithramycin interacts with core histones: An additional mode of action of the DNA groove binder

• Published in: FEBS open bio Vol. 4; no. 1; pp. 987 - 995
• Main Authors: Banerjee, Amrita, Sanyal, Sulagna, Kulkarni, Kirti K., Jana, Kuladip, Roy, Siddhartha, Das, Chandrima, Dasgupta, Dipak
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 01.01.2014; John Wiley & Sons, Inc; Elsevier; Wiley
• Subjects: Acetylation; Antibiotics; Binding sites; Chromatin; Clinical trials; Core histones; Deoxyribonucleic acid; DNA; DNA methylation; DNA microarrays; Dual binding mode; Enzymes; Epigenetic modulator; Epigenetics; Ewing's sarcoma; Experiments; Extinction; Gene expression; Gene regulation; Gene silencing; Genomics; H3K18 acetylation; Histone H3; Histones; Huntingtons disease; Ligands; Lysine; Magnesium; Metal ions; Mithramycin; Osteosarcoma; Physiology; Transcription factors; Tumor cell lines; M2; PTM; MTR; FACS; MTT; CBP; BSA; EWS-FLI1; H3K18Ac; Dual binding mode; Core histones; PBS; CD; BAC; EM; TBST; H3K18 acetylation; Epigenetic modulator; NIH; TCA; Mithramycin; ITC; HAT; HD; SGR; PTM, post-translational modification; BAC, benzalkonium chloride; ITC, isothermal titration calorimetry; H3K18Ac, histone H3 lysine 18 acetylation; FACS, fluorescence activated cell sorting; EM, electron microscopy; PBS, phosphate-buffered saline; M2+, bivalent metal ion such as Mg2; TCA, trichloroacetic acid; SGR, sanguinarine; TBST, Tris-buffered saline Tween-20; MTT, 3-(4-5 dimethylthiazol-2-yl) 2-5diphenyl-tetrazolium bromide; BSA, bovine serum albumin; EWS-FLI1, transcription factor with a DNA binding domain FLI1 and a transcription enhancer domain EWS; NIH, National Institutes of Health; HAT, histone acetyltransferase; CBP, CREB-binding protein; HD, Huntington’s disease; MTR, mithramycin; CD, circular dichroism
• ISSN: 2211-5463; 2211-5463
• DOI: 10.1016/j.fob.2014.10.007

•Mithramycin (MTR) binds to core histones but not to linker histone H1.•Unlike MTR–DNA interaction, MTR–histone association is metal independent.•MTR alters H3K18 acetylation in vitro and ex vivo.•MTR is a dual binder (binds to both DNA and histones) in the chromatin context. Mithramycin (MTR) is a clinically approved DNA-binding antitumor antibiotic currently in Phase 2 clinical trials at National Institutes of Health for treatment of osteosarcoma. In view of the resurgence in the studies of this generic antibiotic as a human medicine, we have examined the binding properties of MTR with the integral component of chromatin – histone proteins – as a part of our broad objective to classify DNA-binding molecules in terms of their ability to bind chromosomal DNA alone (single binding mode) or both histones and chromosomal DNA (dual binding mode). The present report shows that besides DNA, MTR also binds to core histones present in chromatin and thus possesses the property of dual binding in the chromatin context. In contrast to the MTR–DNA interaction, association of MTR with histones does not require obligatory presence of bivalent metal ion like Mg2+. As a consequence of its ability to interact with core histones, MTR inhibits histone H3 acetylation at lysine 18, an important signature of active chromatin, in vitro and ex vivo. Reanalysis of microarray data of Ewing sarcoma cell lines shows that upon MTR treatment there is a significant down regulation of genes, possibly implicating a repression of H3K18Ac-enriched genes apart from DNA-binding transcription factors. Association of MTR with core histones and its ability to alter post-translational modification of histone H3 clearly indicates an additional mode of action of this anticancer drug that could be implicated in novel therapeutic strategies.