Adhesion GPCR ADGRE2 maintains proteostasis to promote progression in acute myeloid leukemia
Acute myeloid leukemia (AML) is an aggressive and heterogenous hematological malignancy. In elderly patients, AML incidence is high and has a poor prognosis due to a lack of effective therapies. G-protein coupled receptors (GPCRs) play integral roles in physiological processes and human diseases. Particularly, one-third of adhesion GPCRs, the second largest group of GPCRs, are highly expressed in hematopoietic stem and progenitor cells or lineage cells. Therefore, we investigated the role of adhesion GPCRs in AML and whether they could be harnessed as anti-leukemia targets. Systematic screening of the impact of adhesion GPCRs on AML functionality by combined bioinformatic and functional analyses revealed high expression of ADGRE2 in AML, particularly in leukemic stem cells (LSCs), which was associated with poor patient outcomes. Silencing ADGRE2 not only exerted anti-leukemia effects in AML cell lines and AML patient-derived cells in vitro but also delayed AML progression in xenograft models in vivo. Mechanistically, ADGRE2 activated PLC-ß/PKC/MEK/ERK signaling to enhance expression of AP-1 and transcriptionally drive expression of DUSP1, a protein phosphatase. DUSP1 de-phosphorylated Ser16 in the J-domain of the co-chaperone DNAJB1, which facilitated DNAJB1-HSP70 interaction and maintenance of proteostasis in AML. Finally, combined inhibition of MEK, AP-1, and DUSP1 exhibited robust therapeutic efficacy in AML xenograft mouse models. Collectively, this study deciphers the roles and mechanisms of ADGRE2 in AML and provides a promising therapeutic strategy for treating AML. Overall design: To investigate the function of adhesion G-protein coupled receptor ADGRE2 in promoting the growth of AML cells and AML progression in vivo, we established the OCI-AML2 cell line in which ADGRE2 has been knocked down by shRNA. We then performed gene expression profiling analysis using data obtained from RNA-Seq of OCI-AML2 cells with control shRNA or shRNA targeting ADGRE2.