LINC01978 drives perineural invasion in cholangiocarcinoma through tumor-neural crosstalk and CCL2-mediated macrophage recruitment.

Perineural invasion (PNI) is a major contributor to the aggressiveness and poor prognosis of cholangiocarcinoma (CCA). However, the crosstalk among tumor cells, the peripheral nervous system, and tumor-associated macrophages (TAMs) within the tumor microenvironment (TME) remains incompletely defined. Using in vitro and in vivo models of PNI, we demonstrate that tumor-derived exosomal LINC01978 mediates neural reprogramming and TAM-associated extracellular matrix (ECM) remodeling. Subsequent analyses of clinical cohorts confirm that high LINC01978 expression is significantly associated with PNI and poorer survival. This mechanism is further validated in human specimens by IHC and IF. Mechanistically, we propose a nerve-coupled dual-loop model that drives PNI in CCA. In the first loop, tumor-derived exosomes deliver LINC01978 to neural cells. This process promotes neurite outgrowth via autocrine glial cell line-derived neurotrophic factor (GDNF) signaling, which in turn activates the RET/STAT3 signaling pathway in CCA cells, thereby promoting malignant phenotypes. After this loop is established, a second loop emerges at the invasive front. Invaded nerves secrete CCL2, thereby preferentially recruiting CCR2+ inflammatory monocytes (IMs) to PNI sites, where they differentiate into TAMs and secrete CTSB to degrade the perineural ECM. Together, the two loops act sequentially and reinforce each other, creating a self-amplifying program that escalates PNI.