RESUMO
Macroautophagy/autophagy, a pathway by which cellular components are sequestered and degraded in response to homeostatic and cell stress-related signals, is required to preserve hematopoietic stem and progenitor cell function. Loss of chromosomal regions carrying autophagy genes and decreased autophagy gene expression are characteristic of acute myeloid leukemia (AML) cells. Deficiency of autophagy proteins is also linked to an altered AML metabolic profile; altered metabolism has recently emerged as a potential druggable target in AML. Here, we sought to understand the mitochondria-specific changes that occur in leukemia cells after knockdown of BNIP3L/Nix or SQSTM1/p62, which are two autophagy genes involved in mitochondrial clearance and are downregulated in primary AML cells. Mitochondrial function, as measured by changes in endogenous levels of reactive oxygen species (ROS) and mitochondrial membrane potential, was altered in leukemia cells deficient in these autophagy genes. Further, these AML cells were increasingly sensitive to mitochondria-targeting drugs while displaying little change in sensitivity to DNA-targeting agents. These findings suggest that BNIP3L or SQSTM1 may be useful prognostic markers to identify AML patients suitable for mitochondria-targeted therapies. Abbreviations: AML: acute myeloid leukemia; DHE: dihydroethidium; mtDNA: mitochondrial DNA; NAO: 10-N-nonyl acridine orange; PD: population doubling; R123: rhodamine 123; ROS: reactive oxygen species; TRC: transduced scramble controls.
Assuntos
Antineoplásicos/farmacologia , Antioxidantes/farmacologia , Proteínas de Membrana/genética , Mitocôndrias/efeitos dos fármacos , Proteínas Proto-Oncogênicas/genética , RNA Interferente Pequeno/farmacologia , Proteína Sequestossoma-1/genética , Proteínas Supressoras de Tumor/genética , Autofagia/efeitos dos fármacos , Autofagia/fisiologia , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Resistencia a Medicamentos Antineoplásicos/genética , Técnicas de Silenciamento de Genes , Células HL-60 , Humanos , Leucemia Mieloide Aguda/tratamento farmacológico , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/metabolismo , Leucemia Mieloide Aguda/patologia , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Proteínas de Membrana/antagonistas & inibidores , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Proteínas Proto-Oncogênicas/antagonistas & inibidores , Espécies Reativas de Oxigênio/metabolismo , Proteína Sequestossoma-1/antagonistas & inibidores , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Células Tumorais Cultivadas , Proteínas Supressoras de Tumor/antagonistas & inibidoresRESUMO
Acute myeloid leukemia (AML) is a devastating disease characterized by poor patient outcome and suboptimal chemotherapeutics. Here, a high-throughput screen identified diosmetin, a citrus flavonoid, with anti-AML activity. Diosmetin imparted selective toxicity against leukemia and leukemia stem cells in vitro and in vivo with no effect on normal hematopoietic stem cells. Mechanistically, we demonstrated that diosmetin targets estrogen receptor (ER) ß. ERß expression conferred cell sensitivity, as patient-derived AML cells with high levels of ERß were sensitive, whereas cells with low ERß were insensitive to diosmetin. Knockdown of ERß confirmed resistance, whereas overexpression enhanced sensitivity to diosmetin, which was demonstrated to be mediated by reactive oxygen species signaling. In summary, these studies highlight targeting of ERß with diosmetin as a potential novel therapeutic strategy for the treatment of AML. Mol Cancer Ther; 16(11); 2618-26. ©2017 AACR.