Single-cell and spatial dissection of precancerous lesions underlying the initiation process of oral squamous cell carcinoma

Precancerous lesions of the oral mucosa, especially those accompanied by moderate to severe dysplasia, contribute to the initiation of oral squamous cell carcinoma (OSCC). However, the cellular compositions and spatial organization of the precancerous stage and how these factors promote human OSCC initiation remain unclear. Here, we built a single-cell transcriptome atlas and a spatial transcriptome map after obtaining data from pairwise human oral mucosal biopsies of 9 individuals consisting of very early-stage OSCC, adjacent precancerous lesions with moderate to severe dysplasia, as well as a matched normal region. An altered epithelial gene-expression profile was identified which favored OSCC initiation. This observation was coupled with distinct fibroblast, monocytic, and regulatory T-cell subclusters involved in reshaping the microenvironment. In particular, a unique immune-inhibitory monocyte subtype and spatial-switching regulation of VEGF signaling were observed surrounding precancerous lesions, concertedly strengthening activities in promoting cancer initiation. Collectively, our work elucidated the cellular landscapes and roles of precancerous lesions underlying OSCC initiation, which is essential for understanding the entire OSCC initiation process and helps inform therapeutic strategies for cancer intervention.