HMGB1 translocation is involved in the transformation of autophagy complexes and promotes chemoresistance in leukaemia

Abstract

Acute lymphoblastic leukaemia (ALL) is a common paediatric cancer and is among the most curable cancers. However, the acquisition of drug resistance is a significant obstacle to the achievement of favourable outcomes, and autophagy is regarded as a mechanism that underlies chemoresistance. In this study, RT-qPCR was used to measure the expression of HMGB1 and Beclin1 in bone marrow mononuclear cells. A CCK-8 test was conducted to assess cell viability. Western blot, immunofluorescence and transmission electron microscopic analyses were performed to evaluate the autophagy levels. Immunoprecipitation analysis was performed to detect protein-protein interactions in the autophagy complexes. We found that HMGB1 expression correlated with the clinical status of ALL. In vitro, anticancer agent-induced cytotoxic effects were associated with autophagy-related drug resistance, and these effects were ameliorated by FIP200 depletion or the application of autophagy inhibitors. Moreover, the Ulk1‑Atg13-FIP200 complex, which promotes HMGB1 trafficking, acted upstream of the HMGB1-Beclin1 and PI3KC3-Beclin1 complexes and played a critical role in autophagy. Targeting the transformation of autophagic complexes or HMGB1 translocation may suppress autophagy and consequently overcome chemoresistance in leukaemia.