Restoration of N-glycosylation via leucine-activated leucyl-tRNA synthetase 1 overcomes chemoresistance in intrahepatic cholangiocarcinoma.

Intrahepatic cholangiocarcinoma (iCCA) is a highly lethal liver malignancy with poor response rates to chemotherapy. Although translational reprogramming is a recognised hallmark of treatment resistance, its role in iCCA remains unclear. This study aimed to investigate codon-biased translation in iCCA chemoresistance and explore potential therapeutic strategies. Proteomic data and tumour specimens were utilised to identify key proteins associated with prognosis in iCCA. Functional analyses and mechanistic studies were conducted using cell cultures, conditional knockout mouse models, and two hydrodynamic transfection iCCA models. N-glycoproteomics, polysome profiling, and ribosome-nascent chain sequencing (RNC-seq) were employed to uncover downstream translational effects. Leucine supplementation was used to activate leucyl-tRNA synthetase 1 (LARS1) to improve chemotherapy efficacy. LARS1 was significantly downregulated in iCCA, particularly in advanced-stage tumours, and positively correlated with patient survival. Using diverse iCCA models, we demonstrated that LARS1 played a pivotal role in regulating iCCA chemoresistance. LARS1 depletion impaired leucyl-tRNA charging and selectively reduced translation of N-glycan biosynthesis enzymes (ALG3, RFT1, and ALG12) via codon-biased hypotranslation. This led to impaired N-glycosylation of ABCC1, thereby enhancing drug efflux activity and promoting chemoresistance. Conversely, exogenous leucine supplementation restored LARS1 expression, rescued the translation of N-glycan biosynthesis enzymes, and markedly improved gemcitabine-oxaliplatin efficacy. This study uncovers a novel mechanism of LARS1-dependent codon-biased translation underlying iCCA chemoresistance. It further establishes leucine supplementation as a potential strategy to improve the efficacy of chemotherapy for iCCA. This study demonstrates that LARS1 downregulation disrupts N-glycan biosynthesis and enhances ABCC1-mediated chemoresistance in intrahepatic cholangiocarcinoma (iCCA). Our findings are important for oncologists and translational researchers, as they identify LARS1-dependent codon-biased translation as a critical determinant of chemotherapy response in iCCA. Practically, we uncover that exogenous leucine supplementation restores LARS1 levels and synergises with gemcitabine-oxaliplatin treatment, offering a safe dietary intervention to overcome chemoresistance. These implications are based on firm preclinical evidence; however, future clinical trials are needed to validate the safety and efficacy of leucine supplementation strategies in patients with iCCA.

Conflict of interest The authors of this study declare that they do not have any conflict of interest. Please refer to the accompanying ICMJE disclosure forms for further details.