Cell death induced by dorsomorphin in adult T-cell leukemia/lymphoma is AMPK-independent.

Adult T-cell leukemia/lymphoma (ATL) is an aggressive T-cell neoplasm with poor prognosis that develops after chronic infection with human T-cell leukemia virus type 1 (HTLV-1). Although AMP-activated protein kinase (AMPK) is a critical cellular energy sensor, it has recently become clear that AMPK can act as a tumor regulator. Here, we assessed the expression of AMPK in primary ATL cells and the effects of dorsomorphin, an AMPK inhibitor, on primary ATL cells and HTLV-1-infected T-cell lines. AMPK expression in acute and chronic ATL patients was significantly higher than in asymptomatic HTLV-1 carriers and healthy donors. Dorsomorphin induced apoptosis in peripheral blood mononuclear cells from ATL patients. Dorsomorphin also induced dose- and time-dependent apoptosis in HTLV-1-infected T-cell lines. Dorsomorphin increased the production of intracellular reactive oxygen species (ROS) and induced ataxia telangiectasia-mutated Ser1981 phosphorylation and p53 accumulation. These results indicated that dorsomorphin induces apoptosis via ROS-mediated DNA damage in HTLV-1-infected T-cell lines. Furthermore, dorsomorphin suppressed the growth of human ATL tumor xenografts in NOD/SCID mice. Together, these data suggest that AMPK could be a candidate therapeutic target for ATL and that dorsomorphin could be a therapeutic agent for ATL.