Fig. 5: The small compound OPA1 inhibitor MYLS22 has anti-leukemic activity in vitro and in vivo.

A–E PDX AML cells or normal CD34⁺ hematopoietic cells were incubated with vehicle or 10–30 μM of the small compound OPA1 inhibitor MYLS22 in methylcellulose. A, B Quantification of mitochondrial length using MTDR/DAPI staining and confocal imaging (63x objective. Scale bars = 2 μm) in PDX cells. C L-CFU assays on PDX AML cells after 7–10 days (n = 3). D Colony formation from normal human CD34⁺ hematopoietic progenitor cells after 10 days (n = 4). Left panel: BFU-E, right panel: CFU-GM. E Representative contour plots (left panel) and cell-cycle phase quantification (right panel) using Ki67/DAPI staining (n = 4). F–I Mice were treated with vehicle or 30 mg/kg MYLS22 by daily intraperitoneal injection during 7 days (n = 12 mice per arm). G Representative contour plots of hCD45 versus mCD45. H Quantification of hCD45⁺ human AML cells. I Quantification of mCD45⁺ murine hematopoietic cells. J MFN2 and OPA1 promote mitochondrial fusion, driving mitochondrial oxidative phosphorylation (OxPhos) and ROS production, which favor leukemic cells proliferation (left panel). After depletion of MFN2 or OPA1, or inhibition of OPA1 by the small compound MYLS22, inhibition of mitochondrial fusion results in ROS depletion and transition from G₁ to G₀ phase of cell cycle (right panel). Vertical bars indicate standard deviations. ns not significant, *p < 0.05, **p < 0.01, ***p < 0.001.