Epithelial–mesenchymal transition in an EcPV2‐positive vulvar squamous cell carcinoma of a mare.

Background: Vulvar squamous cell carcinoma (VSCC) has been recently associated with Equus caballus papillomavirus type 2 (EcPV2) infection. Still, few reports concerning this disease are present in the literature. Objective: To describe a case of naturally occurring EcPV2‐induced VSCC, by investigating tumour ability in undergoing the epithelial‐to‐mesenchymal transition (EMT). Study design: Case report. Methods: A 13‐year‐old Haflinger mare was referred for a rapidly growing vulvar mass. After surgical excision, the mass was submitted to histopathology and molecular analysis. Histopathological diagnosis was consistent with a VSCC. Real‐time qPCR, real‐time reverse transcriptase (RT)‐qPCR and RNAscope were carried out to detect EcPV2 infection and to evaluate E6/E7 oncogenes expression. To highlight the EMT, immunohistochemistry (IHC) was performed. Expression of EMT‐related and innate immunity‐related genes was investigated through RT‐qPCR. Results: Real‐time qPCR, RT‐qPCR and RNAscope confirmed EcPV2 DNA presence and expression of EcPV2 oncoproteins (E6 and E7) within the neoplastic vulvar lesion. IHC highlighted a cadherin switch together with the expression of the EMT‐related transcription factor HIF1α. With RT‐qPCR, significantly increased gene expression of EBI3 (45.0 ± 1.62, p < 0.01), CDH2 (2445.3 ± 0.39, p < 0.001), CXCL8 (288.7 ± 0.40, p < 0.001) and decreased gene expression of CDH1 (0.3 ± 0.57, p < 0.05), IL12A (0.04 ± 1.06, p < 0.01) and IL17 (0.2 ± 0.64, p < 0.05) were detected. Main limitations: Lack of ability to generalise and danger of over‐interpretation. Conclusion: The results obtained were suggestive of an EMT event occurring within the neoplastic lesion. [ABSTRACT FROM AUTHOR]