2. Academic Validation
  3. Biological Evaluation of a Novel Compound with Predicted EZH2 and EED Binding Against Human Malignant Melanoma Cells

Biological Evaluation of a Novel Compound with Predicted EZH2 and EED Binding Against Human Malignant Melanoma Cells

  • Int J Mol Sci. 2026 Mar 13;27(6):2647. doi: 10.3390/ijms27062647.
Sergei Gorbunov 1,  Sotiris Kyriakou 1,  Ioannis Anestopoulos 1,  Shahzaib Khoso 2,  Marcello Manfredi 2 3,  Rodrigo Franco 4 5,  Aglaia Pappa 6,  Mihalis I Panayiotidis 1 7
Affiliations

Affiliations

  • 1 Department of Cancer Genetics, Therapeutics and Ultrastructural Pathology, The Cyprus Institute of Neurology and Genetics, Nicosia 2371, Cyprus.
  • 2 Department of Translational Medicine, Center for Translational Research on Autoimmune and Allergic Diseases, University of Piemonte Orientale, 28100 Novara, Italy.
  • 3 Institute for Molecular and Translational Cardiology (IMTC), IRCCS Policlinico San Donato, 20097 Milan, Italy.
  • 4 Redox Biology Centre, University of Nebraska-Lincoln, Lincoln, NE 68583, USA.
  • 5 Department of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583, USA.
  • 6 Department of Molecular Biology and Genetics, Democritus University of Thrace, 68100 Alexandroupolis, Greece.
  • 7 Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, Starkville, MS 39762, USA.
PMID: 41898517 DOI: 10.3390/ijms27062647
Abstract

Enhancer of Zeste Homolog 2 (EZH2), the catalytic subunit of Polycomb Repressive Complex 2 (PRC2), mediates histone H3 lysine 27 trimethylation (H3K27me3), an epigenetic modification associated with transcriptional repression. EZH2 inhibitors (EZH2is) gained attention after the first-in-class drug Tazemetostat received FDA approval for treating epithelioid sarcoma. Preclinical studies suggest that EZH2is could be effective against melanoma, but their general inability to cross the blood-brain barrier (BBB), among Others, limits the treatment of secondary brain metastases. Based on these limitations, we designed SG-8, a novel compound derived from TDI-6118 (a known brain-penetrant EZH2i). In silico docking predicted that SG-8 may exhibit high affinity for EZH2 as well as for another PRC2 subunit, Embryonic Ectoderm Development (EED). In addition, in vitro PAMPA assays suggested passive BBB permeability of SG-8. In cell-based assays, SG-8 and the structurally related EZH2i PF-06726304 displayed lower cytotoxicity than Tazemetostat in both primary (A375) and metastatic (Colo-679) human melanoma cells. Western blot analysis showed that SG-8 and PF-06726304 markedly reduced EED protein levels and, to a lesser extent, EZH2 levels, without affecting total H3K27me3, consistent with preserved canonical PRC2 activity. Instead, treatment with both compounds-most prominently SG-8-was associated with reduced phosphorylation levels of EZH2 (Ser21) and its upstream regulator Akt (Ser473), suggesting that modulation of the Akt-EZH2 signaling axis may at least partially contribute to their anti-melanoma activity.

Keywords

EED; EZH2; H3K27 methylation; PRC2; Tazemetostat; blood–brain barrier; histone methyltransferase; malignant melanoma.

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