Single-cell analysis reveals that GFAP+ dedifferentiated Schwann cells promote tumor progress in PNI-positive distal cholangiocarcinoma via lactate/HMGB1 axis

Distal cholangiocarcinoma (dCCA) is a highly lethal malignancy that accounts for approximately 40% of patients with primary cholangiocarcinoma. Remarkable cellular heterogeneity and perineural invasion (PNI) are two typical features of dCCA. Deciphering the complex interplay between neoplastic and neural cells is crucial for understanding the mechanisms propelling PNI-positive dCCA progression. Herein, we conduct single-cell RNA sequencing on 24,715 cells from two pairs of PNI-positive dCCA tumors and adjacent tissues, identifying eight unique cell types. Malignant cells exhibit significant inter- and intra-tumor heterogeneity. We delineate the compositional and functional phenotypes of five Schwann cell (SC) subsets in PNI-positive dCCA. Moreover, our analyses reveal two potential cell subtypes critical to forming PNI: NEAT1⁺ malignant cells characterized by hypoxic propensity and GFAP⁺ dedifferentiated SCs featuring hypermetabolism. Further bioinformatics uncover extensive cellular interactions between these two subpopulations. Functional experiments confirm that lactate in the hypoxic tumor microenvironment can induce GFAP-dedifferentiation in SCs, which promotes cancer cell invasion and progression through upregulating HMGB1. Taken together, our findings offer a thorough characterization of the transcriptional profile in PNI-positive dCCA and unveil potential therapeutic targets for dCCA PNI.