Norepinephrine promotes tumour cell aggressiveness and NK cell ferroptosis via ADRB2 in intrahepatic cholangiocarcinoma with perineural invasion.

Abstract

Sympathetic signalling plays a critical role in the initiation and progression of various malignancies. However, its specific contribution to intrahepatic cholangiocarcinoma (iCCA) remains poorly understood. This study aimed to investigate the effects and underlying mechanisms of sympathetic signalling on tumour and immune cells, and to explore the potential efficacy of targeting sympathetic pathways in iCCA characterised by perineural invasion (PNI). Single-cell RNA sequencing was employed to elucidate the impact of PNI on iCCA. <i>In vivo</i> and <i>in vitro</i> experiments were conducted to decipher the molecular mechanisms. Preclinical models were used to investigate the therapeutic potential of targeting sympathetic signalling. Tyrosine hydroxylase-positive sympathetic nerve fibres were detected in PNI⁺ iCCA, accompanied by elevated norepinephrine (NE). We constructed an atlas of PNI⁺ iCCA at single-cell transcriptional level, characterised by <i>MDK</i> overexpression and reduced infiltration of CD56^dimCD16⁺ natural killer (NK) cells. Mechanistically, NE was found to upregulate MDK expression via the ADRB2/PI3K-AKT/p65 axis, thereby promoting tumour progression of PNI⁺ iCCA. Furthermore, NE might induce NK cell ferroptosis by triggering an imbalance in glutamate/cysteine metabolism in PNI⁺ iCCA via ADRB2. Loss of sympathetic innervation in mice reduced NE concentrations and MDK expression, while increasing NK cell infiltration and inhibiting tumour growth. Preliminary results suggested that blockers of β-adrenergic receptors suppressed iCCA progression. This study uncovers a novel neuro-immune-tumour axis in iCCA and provides a mechanistic rationale for targeting β-adrenergic signalling as a possible therapeutic strategy for PNI⁺ iCCA.