Single-cell Transcriptomics Dissects Premalignant Progression in Proliferative Verrucous Leukoplakia

Proliferative verrucous leukoplakia (PVL) is a potentially malignant disorder characterized by contiguous spread, a spectrum of clinicopathological features and high malignant transformation risk. Despite many efforts to describe the clinicopathological features of PVL progression, so far, there is still a lack of knowledge on the dynamic changes in molecular signature during this process. Hence, we applied single-cell RNA sequencing to 3 biopsy samples from a large PVL lesion. These samples exhibited the histopathological continuum of PVL lesions progression. By analysis for transcriptome profiling of 27,611 cells from these samples, we identified 10 major cell lineages and revealed the cellular remodeling occurring in the progression of PVL lesions, including epithelial, stromal and immune cells. The epithelial cells are shifted to pro-tumorigenic transcriptional cell states and secretory patterns at premalignant stage. Immune cells showed growing immunosuppressive phenotypes during PVL progression. Remarkably, two novel cell subtypes INSR+ endothelial cells and ASPN+ fibroblasts were discovered and may play a vital role in microenvironment remodeling, such as angiogenesis and stromal fibrosis, closely involved in the malignant transformation. Our work preliminarily describes the dynamic molecular properties of PVL lesions, enhances the systematic understanding of the premalignant evolution of PVL and attempts to provide the framework for future research. 3 samples taken from an large lesion present a pathological continnum of oral proliferative verrucous leukoplakia