S-palmitoylation of c-MET by CK2α-mediated zDHHC15 phosphorylation drives glioblastoma stem cell tumorigenicity

Abstract

Background: The c-MET signaling pathway is crucial for the self-renewal and tumorigenic capacity of cancer stem cells, including glioblastoma stem cells (GSCs). Despite its recognized importance, the precise mechanisms of c-MET activation in these cells remain elusive. This study aimed to elucidate the key regulatory elements and mechanisms governing c-MET function in GSCs.

Methods: The mediation of S-palmitoylation and dimerization of c-MET by zDHHC15 was validated using metabolic labeling, acyl-PEG exchange (APE), BS3 crosslinking, and co-immunoprecipitation. The role of the CK2α-zDHHC15-c-MET axis in tumorigenesis, along with the anti-tumor efficacy of TVB-3166, was confirmed through cell proliferation, limiting dilution, and intracranial tumor growth assays.

Results: We revealed that zDHHC15, a member of the DHHC family of palmitoyl acyltransferases, mediates the palmitoylation of c-MET at Cys801, which is critical for c-MET O-glycosylation, dimerization, and activation. We further identified a novel regulatory loop in which CK2α phosphorylates zDHHC15 at Tyr92, increasing its stability and c-MET binding, thereby enhancing c-MET palmitoylation. zDHHC15 was found to be specifically enriched in GSCs, and its targeted knockdown markedly impaired their self-renewal and tumorigenic capabilities both in vitro and in vivo. Therapeutically, we introduced TVB-3166, an inhibitor of c-MET S-palmitoylation, which demonstrated robust inhibitory effects on GSC growth in orthotopic xenograft models.

Conclusions: This study establishes the CK2α-zDHHC15-c-MET axis as a pivotal regulatory hub in GSC maintenance and identifies c-MET S-palmitoylation as a novel and promising therapeutic target for the treatment of glioblastoma.

Keywords: CK2α; S-palmitoylation; c-MET; glioblastoma stem cells; zDHHC15.