KRAS mutation-driven O-GlcNAcylation of CLDN18.2 enhances the progression of pancreatic cancer and reduces the efficacy of CLDN18.2-targeted therapy

Background CLDN18.2 has emerged as a promising therapeutic target in gastric and gastro-oesophageal junction cancers. However, its clinical efficacy in pancreatic ductal adenocarcinoma (PDAC) has been modest, suggesting the presence of regulatory mechanisms impairing its efficacy. Objective We aim to investigate how O-linked N-acetylglucosaminylation (O-GlcNAcylation) affects CLDN18.2 subcellular localisation, tumour progression and therapeutic resistance in PDAC, while exploring strategies to restore treatment sensitivity. Design This study used samples from patients with PDAC, along with the following models: humanised patient-derived xenograft (PDX), patient-derived organoids (PDOs), orthotopic PDO xenograft, KPC mice (LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx1-Cre) and KPC-Cldn18.2 knockout (KO) mice. Results KRAS (Kirsten rat sarcoma viral oncogene homolog) mutation and hyperglycaemia cooperatively drive CLDN18.2 O-GlcNAcylation at T204, promoting CLDN18.2 cytoplasmic accumulation. O-GlcNAcylated CLDN18.2 promotes pancreatic cancer migration, invasion and metastases and reduces its sensitivity to anti-CLDN18.2 based targeted therapy. Mechanistically, O-GlcNAcylated CLDN18.2 exhibits reduced binding to PTP1B, leading to enhanced tyrosine phosphorylation. O-GlcNAcylated CLDN18.2 recruits Src via SH2 domain, triggering Src activation. Genetic (T204A) or pharmacological blockade of O-GlcNAcylation restores CLDN18.2 membrane localisation and suppresses tumour progression. Therapeutically, low-dose MRTX1133 (KRAS G12D inhibitor) reduces O-GlcNAcylation and synergises with CLDN18.2-targeted therapy in KRAS mutant PDAC models with minimal side effects. Conclusions KRAS mutations and hyperglycaemia drive O-GlcNAcylation of CLDN18.2 at its C-terminal T204 site. O-GlcNAcylated CLDN18.2 promotes poor prognosis and reduces the effectiveness of CLDN18.2-targeted therapies. Low dose MRTX1133 restores CLDN18.2 membrane localisation by reducing its O-GlcNAcylation and augments CLDN18.2-targeted therapy efficacy, offering a novel combinatorial strategy for KRAS-mutant PDAC.