RESUMO
BACKGROUND: Cardiac glycosides are approved for the treatment of heart failure as Na+/K+ pump inhibitors. Their repurposing in oncology is currently investigated in preclinical and clinical studies. However, the identification of a specific cancer type defined by a molecular signature to design targeted clinical trials with cardiac glycosides remains to be characterized. Here, we demonstrate that cardiac glycoside proscillaridin A specifically targets MYC overexpressing leukemia cells and leukemia stem cells by causing MYC degradation, epigenetic reprogramming and leukemia differentiation through loss of lysine acetylation. METHODS: Proscillaridin A anticancer activity was investigated against a panel of human leukemia and solid tumor cell lines with different MYC expression levels, overexpression in vitro systems and leukemia stem cells. RNA-sequencing and differentiation studies were used to characterize transcriptional and phenotypic changes. Drug-induced epigenetic changes were studied by chromatin post-translational modification analysis, expression of chromatin regulators, chromatin immunoprecipitation, and mass-spectrometry. RESULTS: At a clinically relevant dose, proscillaridin A rapidly altered MYC protein half-life causing MYC degradation and growth inhibition. Transcriptomic profile of leukemic cells after treatment showed a downregulation of genes involved in MYC pathways, cell replication and an upregulation of hematopoietic differentiation genes. Functional studies confirmed cell cycle inhibition and the onset of leukemia differentiation even after drug removal. Proscillaridin A induced a significant loss of lysine acetylation in histone H3 (at lysine 9, 14, 18 and 27) and in non-histone proteins such as MYC itself, MYC target proteins, and a series of histone acetylation regulators. Global loss of acetylation correlated with the rapid downregulation of histone acetyltransferases. Importantly, proscillaridin A demonstrated anticancer activity against lymphoid and myeloid stem cell populations characterized by MYC overexpression. CONCLUSION: Overall, these results strongly support the repurposing of proscillaridin A in MYC overexpressing leukemia.
Assuntos
Antineoplásicos/efeitos adversos , Expressão Gênica/efeitos dos fármacos , Genes myc , Insuficiência Cardíaca/etiologia , Leucemia/genética , Lisina/metabolismo , Proscilaridina/efeitos adversos , Acetilação , Antineoplásicos/uso terapêutico , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Cromatina/genética , Cromatina/metabolismo , Relação Dose-Resposta a Droga , Epigênese Genética/efeitos dos fármacos , Perfilação da Expressão Gênica , Histonas/metabolismo , Humanos , Leucemia/complicações , Leucemia/tratamento farmacológico , Leucemia/metabolismo , Modelos Biológicos , Proscilaridina/uso terapêutico , Linfócitos T/citologia , Linfócitos T/efeitos dos fármacos , Linfócitos T/metabolismoRESUMO
Targeting DNA hypermethylation, using nucleoside analogs, is an efficient approach to reprogram cancer cell epigenome leading to reduced proliferation, increased differentiation, recognition by the immune system, and ultimately cancer cell death. DNA methyltransferase inhibitors have been approved for the treatment of myelodysplastic syndromes, chronic myelomonocytic leukemia, and acute myelogenous leukemia. To improve clinical efficacy and overcome mechanisms of drug resistance, a second generation of DNA methyltransferase inhibitors has been designed and is currently in clinical trials. Although efficient in monotherapy against hematologic malignancies, the potential of DNA methyltransferase inhibitors to synergize with small molecules targeting chromatin or immunotherapy will provide additional opportunities for their future clinical application against leukemia and solid tumors.