Spatial Transcriptome Analysis Reveals Factors Involved in Actinic Cheilosis Transformation to Squamous Cell Carcinoma of the Lip

Lip squamous cell carcinomas (SCC) often arise from actinic cheilitis. However, the factors driving oncogenic transformation and determinants of lip SCC differentiation are unclear. This study investigated the differences between lip SCC and premalignant actinic cheilitis and factors related to tumor differentiation. We included patients who received biopsies for actinic cheilitis that later progressed to lip SCC. Moreover, well-differentiated lip SCC and moderately-to-poorly differentiated lip SCC were selected for spatial transcriptomic analysis, using pan-cytokeratin and CD45 as morphology markers. In pan-cytokeratin–positive tumor areas, we detected 5 upregulated differentially expressed genes ( KLK13 , MGST1 , LNX1 , NDRGZ , and HMOX1 ) and 1 downregulated differentially expressed gene ( HOXD11 ) in lip SCCs compared with those in premalignant lesions. Endosomal transport, lysosomal transport, macroautophagy, and wound-healing pathways were significantly upregulated in lip SCC compared with those in actinic cheilitis. Furthermore, proteolysis- and hypoxia-related differentially expressed genes were found in moderately-to-poorly differentiated lip SCC compared with those in well-differentiated lip SCC. General cancer-associated fibroblast markers ( P = .021) were increased in actinic cheilitis preceding moderately-to-poorly differentiated lip SCCs compared with those in actinic cheilitis preceding well-differentiated lip SCCs, which was validated in immunohistochemical staining. This observation could expand our understanding of the changes in the microenvironment composition during lip SCC carcinogenesis and according to lip SCC differentiation.