Enhanced Spatial Colocalization and Communication of Oral Squamous Cell Carcinoma and Stromal Fibroblasts in Patients with Lymph Node Metastasis

Lymph node metastasis (LNM) is a critical prognostic factor for patients with oral squamous cell carcinoma (OSCC). Although bulk and single-cell analyses have provided reference OSCC profiles, data without spatial information remain insufficient for identifying regions of the OSCC tumor microenvironment (TME) from which LNM-related factors arise. Here, we applied formalin-fixed paraffin-embedded spatial transcriptomics to examine OSCC cell transcriptomes and reconstruct the landscape in which cell–cell interactions occur in the TME. OSCC cells and stromal fibroblasts were spatially colocalized at a higher level in tumor-invasive lesions in patients with LNM than in patients without LNM. Furthermore, spatially organized intercellular communication was more active in LNM samples. These results were corroborated by immunohistochemistry. This study provides insights into the spatial colocalization of OSCC cells and stromal fibroblasts associated with LNM, which could improve early diagnosis of micrometastasis that is undetectable via imaging, as well as the associated prognosis.Funding Information: This study was supported in part by the Japan Society for the Promotion of Science KAKENHI Program (grant numbers JP17K17233 [to K.F.] and JP20K18716 [to R.I.]) and by the Uehara Memorial Foundation (to K.F. and Y.S.).Declaration of Interests: The authors declare no competing interests.Ethics Approval Statement: This study was conducted following the principles of the Declaration of Helsinki. Clinical specimens from patients with untreated primary OSCC were used for spatial gene expression analysis. Approval was obtained from the Human Research Ethics Committee of Hirosaki University Graduate School of Medicine (approval # 2021-081, jRCT1020210053). Written informed consent was obtained from all participants, and consent included the use of all de-identified patient data for publication. Participants were not compensated.