Abstract
Simple SummarySquamous cell carcinoma (SCC) is one of the most common cancers in horses, and it can arise at any site on the skin and mucosae. Recent studies associated equine papillomavirus type 2 (EcPV2) infections with this type of cancers of the oral tract and genitals. Larynx and pharynx are frequently recognized as sites of SCC. In humans, squamous cell carcinoma of the larynx (SCCL) is a common cancer associated with papilloma virus (PV) infection and epithelial to mesenchymal transition (EMT). EMT can occur under different biological conditions, upon the same programmed changes: embryogenesis and organ development fibrosis, wound healing, and cancer metastases. This work reports for the first time in a SCCL of a horse a wide immunohistochemical EMT characterization, by analyzing main epithelial markers (E-cadherin, β-catenin, and pan-cytokeratin AE3/AE1), main mesenchymal markers (N-cadherin and vimentin), and the main EMT-related transcription factors (TWIST-1, ZEB-1, and HIF-1α). This work illustrates an example of tumor cell adaptation during the metastatic process in the equine SCCL, taking also into consideration the potential influence provided by EcPV2 oncoproteins on the EMT process.Squamous cell carcinoma (SCC) is one of the most frequent tumors of skin and muco-cutaneous junctions in the horse. Equine papillomavirus type 2 (EcPV2) has been detected in equine SCC of the oral tract and genitals, and recently also in the larynx. As human squamous cell carcinoma of the larynx (SCCL), it is strongly etiologically associated with high-risk papillomavirus (h-HPV) infection. This study focuses on tumor cells behavior in a naturally occurring tumor that can undergo the so-called epithelial to mesenchymal transition (EMT). A SCCL in a horse was investigated by immunohistochemistry using antibodies against E-cadherin, pan-cytokeratin AE3/AE1, β-catenin, N-cadherin, vimentin, ZEB-1, TWIST, and HIF-1α. EcPV2 DNA detection and expression of oncogenes in SCC were investigated. A cadherin switch and an intermediate filaments rearrangement within primary site tumor cells together with the expression of the EMT-related transcription factors TWIST-1, ZEB-1, and HIF-1α were observed. DNA obtained from the tumor showed EcPV2 positivity, with E2 gene disruption and E6 gene dysregulation. The results suggest that equine SCCL might be a valuable model for studying EMT and the potential interactions between EcPV2 oncoproteins and the EMT process in SCCL.
Highlights
In horses and other equids, squamous cell carcinoma (SCC) is the most common malignant skin neoplasia, and accounts for 7–37% of equine skin lesions [1]
Equine oral SCC is invasive and lymph node metastases were reported in 30% of horses with oral SCC [4]
A 17-year-old female, 550 Kg, Maremmano Horse was referred with severe clinical signs due to a dorso-cranial dislocation of the epiglottis which caused the reduction of 70% of the laryngeal lumen, diagnosed by an endoscopic exam, performed under sedation with butorphanol combined with detomidine [23]
Summary
In horses and other equids, squamous cell carcinoma (SCC) is the most common malignant skin neoplasia, and accounts for 7–37% of equine skin lesions [1]. SCC can arise at any site on the skin and mucosa. Non-pigmented skin and muco-cutaneous junctions have been reported to be preferential SCC sites [2,3]. Larynx and pharynx are reported to be sites of SCC development in horses. Equine oral SCC is invasive and lymph node metastases were reported in 30% of horses with oral SCC [4]. The longest survival time reported in 11 horses with laryngeal SCC was 4 months [4]
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