TP53 mutations orchestrate partial EMT states in oral squamous cell carcinoma: spatially resolved and in vitro preliminary insights into tumour plasticity

Abstract TP53 is the most frequently mutated gene in oral squamous cell carcinoma (OSCC); however, its role in promoting epithelial–mesenchymal transition (EMT) and tumour progression remains unclear, particularly within the context of intra‐tumour heterogeneity. We performed multi‐regional whole‐exome sequencing (WES) on 43 tumour regions from nine OSCC patients, including matched lymph node metastases. p53, epithelial, and mesenchymal markers were assessed by conventional and multiplexed immunofluorescence (MxIF), followed by digital image analysis using HALO software. EMT‐associated gene expression was quantified by RT‐qPCR. In vitro assays were performed in epithelial cell lines transiently transfected with the hotspot mutant p53R248Q. TP53 mutations were detected in 7 of 9 patients (77.8%), predominantly as missense mutations in the DNA‐binding domain. Mutant tumours exhibited strong nuclear and cytoplasmic p53 accumulation, accompanied by reduced E‐cadherin and increased vimentin expression. MxIF revealed a higher proportion of partial EMT‐like cells (PCK + vimentin + ) in mutant tumours ( p < 0.05). RT‐qPCR showed upregulation of VIM , SLUG , ZEB1 , and ZEB2 in TP53 ‐mutant tumours. In vitro , p53R248Q expression increased N‐cadherin levels, disrupted E‐cadherin membrane localisation, and altered F‐actin organisation at the junctions, consistent with EMT‐associated phenotypic changes. Collectively, our findings suggest that TP53 mutations, particularly p53R248Q, are associated with partial EMT activation in OSCC. These findings highlight a potential link between TP53 mutations and EMT‐related changes in OSCC, suggesting that mutant p53 may contribute to tumour phenotypic plasticity. © 2026 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.