The poor prognosis of
acute myeloid leukemia (AML) and the highly heterogenous nature of the disease motivates targeted gene therapeutic investigations. Rho-associated
protein kinases (ROCKs) are crucial for various actin cytoskeletal changes, which have established malignant consequences in various
cancers, yet are still not being successfully utilized clinically towards
cancer treatment. This work establishes the therapeutic activity of ROCK inhibitor (5Z)-2-5-(1H-pyrrolo[2,3-
b]pyridine-3-ylmethylene)-1,3-thiazol-4(5H)-one (DJ4) in both in vitro and in vivo preclinical models of AML to highlight the potential of this class of inhibitors. Herein, DJ4 induced cytotoxic and proapoptotic effects in a dose-dependent manner in human AML cell lines (IC50: 0.05-1.68 μM) and primary patient cells (IC50: 0.264-13.43 μM); however, normal hematopoietic cells were largely spared. ROCK inhibition by DJ4 disrupts the phosphorylation of downstream targets,
myosin light chain (MLC2) and
myosin-binding subunit of MLC
phosphatase (MYPT), yielding a potent yet selective treatment response at micromolar concentrations, from 0.02 to 1 μM. Murine models injected with
luciferase-expressing
leukemia cell lines subcutaneously or intravenously and treated with DJ4 exhibited an increase in overall survival and reduction in
disease progression relative to the vehicle-treated control mice. Overall, DJ4 is a promising candidate to utilize in future investigations to advance the current AML
therapy.