Tumor Cell Plasticity in Equine Papillomavirus-Positive Versus-Negative Squamous Cell Carcinoma of the Head and Neck.

Carina Strohmayer,Sabine Brandt,Ingrid Walter,Christoph Jindra,Stefan Kummer,Christiane Weissenbacher-Lang,Sibylle Kneissl,Andrea Klang,Torben Redmer

doi:10.3390/pathogens11020266

Carina Strohmayer, Sabine Brandt + Show 7 more

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https://doi.org/10.3390/pathogens11020266

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Abstract

Squamous cell carcinoma of the head and neck (HNSCC) is a common malignant tumor in humans and animals. In humans, papillomavirus (PV)-induced HNSCCs have a better prognosis than papillomavirus-unrelated HNSCCs. The ability of tumor cells to switch from epithelial to mesenchymal, endothelial, or therapy-resistant stem-cell-like phenotypes promotes disease progression and metastasis. In equine HNSCC, PV-association and tumor cell phenotype switching are poorly understood. We screened 49 equine HNSCCs for equine PV (EcPV) type 2, 3 and 5 infection. Subsequently, PV-positive versus -negative lesions were analyzed for expression of selected epithelial (keratins, β-catenin), mesenchymal (vimentin), endothelial (COX-2), and stem-cell markers (CD271, CD44) by immunohistochemistry (IHC) and immunofluorescence (IF; keratins/vimentin, CD44/CD271 double-staining) to address tumor cell plasticity in relation to PV infection. Only EcPV2 PCR scored positive for 11/49 equine HNSCCs. IHC and IF from 11 EcPV2-positive and 11 EcPV2-negative tumors revealed epithelial-to-mesenchymal transition events, with vimentin-positive cells ranging between <10 and >50%. CD44- and CD271-staining disclosed the intralesional presence of infiltrative tumor cell fronts and double-positive tumor cell subsets independently of the PV infection status. Our findings are indicative of (partial) epithelial–mesenchymal transition events giving rise to hybrid epithelial/mesenchymal and stem-cell-like tumor cell phenotypes in equine HNSCCs and suggest CD44 and CD271 as potential malignancy markers that merit to be further explored in the horse.

Highlights

Squamous cell carcinoma (SCC) is a common epithelial tumor type in humans and animals that arises from cutaneous or mucosal keratinocytes
The major findings of this study indicate that equine head and neck SCCs (HNSCC) can be categorized into EcPV2-related and -unrelated HNSCC subtypes, at a similar ratio as determined for high-risk human PVs (hrHPVs)-induced versus -unrelated HNSCCs in humans
We provide evidence of (p)epithelial–mesenchymal transition (EMT) occurring in virtually all lesions to a various extent, and, importantly, of the presence CD44+ CD271+ tumor cell subsets that likely represent cancer stem(-like) cell” (CSC)

Summary

Introduction

Squamous cell carcinoma (SCC) is a common epithelial tumor type in humans and animals that arises from cutaneous or mucosal keratinocytes. Virtually 100% of cervical carcinomas, about 50% of anogenital SCCs, and approximately 25% of head and neck SCCs (HNSCC) are causally associated with infection by carcinogenic papillomaviruses (PVs) [1]. These PVs termed high-risk human PVs (hrHPVs) belong to the genus α-PVs. These PVs termed high-risk human PVs (hrHPVs) belong to the genus α-PVs Despite their high genetic heterogeneity, hrHPVs share common features. These include their ability to transform normal keratinocytes into highly proliferative neoplastic cells by a concerted action of the oncoproteins E6 and E7 [2], and to escape from immune surveillance via E5 oncoprotein-mediated downregulation of the MHC class I [3]. There is evidence of Epstein-Barr virus—a γ-Herpesvirus—contributing to the onset and progression of certain HNSCC subtypes, such as oral SCC [6]

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