Ligand‐Receptor Interactions Between Squamous and Endothelial Cells Induce Head and Neck Squamous Cell Carcinoma

Advances in narrowband imaging (NBI) have revealed that squamous epithelial lesions form alongside changes in squamous epithelial cells and intrapapillary capillary loops (IPCLs) in the head and neck. However, the molecular interactions between squamous epithelial cells and endothelial cells (ECs) that promote IPCL proliferation are unclear. This study aimed to identify the mechanisms of cooperation between parenchymal squamous cells and stromal IPCLs during the formation of head and neck squamous cell carcinoma (SCC). We investigated ligand-receptor interactions between squamous epithelial and endothelial cells of IPCLs using Visium analysis on frozen, formalin-fixed and paraffin-embedded (FFPE) tissues from hypopharyngeal squamous epithelial lesions. We examined the protein expression in hypopharyngeal superficial squamous epithelial lesions using immunohistochemistry and immunofluorescence. mRNA expression levels of these genes in SCC and non-tumor tissues were analyzed using RT-qPCR. Phenotypic changes were analyzed by inducing candidate genes into SCC cell lines via a lentivirus system. Visium analysis revealed that Fibronectin 1 (FN1) acted as a ligand in endothelial cells, Cellular communication network factor 1 (CCN1) as a ligand in SCC cells, and Integrin subunit alpha V (ITGAV) as a receptor for both FN1 and CCN1. The expression of these three candidates increased in low-grade dysplasia, an early stage of neoplastic lesions, and was significantly higher in invasive SCCs, except for CCN1. When ITGAV was introduced into SCC cell lines (FaDu and Detroit 562) and HaCaT cells treated with FN1, the cells showed increased proliferation ability. SCC develops via ligand-receptor molecular interactions between squamous epithelial and vascular endothelial cells in IPCLs.