Equine Genital Squamous Cell Carcinoma: In Situ Hybridization Identifies a Distinct Subset Containing Equus caballus Papillomavirus 2.

This study investigates Equus caballus papillomavirus 2 (EcPV2) as a potential cause of genital squamous cell carcinomas (SCC), a common malignant tumor in horse genitalia. Using a sensitive in situ hybridization technique, researchers identify EcPV2 in a distinct subset of genital SCCs in horses, providing more extensive evidence of the virus’s role in these types of cancers.

Research Purpose

• The study was carried out to investigate the role of EcPV2 in the formation of genital SCCs in horses. Although EcPV2 was known to be present on normal horse genitalia, its role in cancer development remained unclear. The researchers aimed to shed more light on this issue.

Methodology

• The researchers employed a novel, highly sensitive technique known as chromogenic in situ hybridization (ISH).
• The ISH technique was designed to target the E6/E7 oncogenes of EcPV2, key genes in virus development and transformation.
• The study involved 13 samples of penile and preputial squamous cell carcinomas, in which the presence and abundance of EcPV2 were then evaluated using the newly developed ISH method.

Findings

• EcPV2 was abundantly present in 6 out of the 13 examined SCC samples, indicating its potential role in the development of these specific types of tumors.
• The 6 samples that didn’t display EcPV2 presence showed signs of solar damage, suggesting different causes for the SCCs.
• ISH method successfully proved for the first time that the majority of neoplastic cells (abnormal, cancerous cells) contain the virus.
• In all the explored metastases (cells distant from the original tumor), the presence of EcPV2 was identified via ISH, which assumes the stability of E6/E7 expression in these cells.

Conclusions

• This study strengthens the evidence supporting the role of EcPV2 in the induction of genital SCCs in horses.
• The ISH technique presented has proven valuable for studying the pathogenesis of these types of tumors and establishing the widespread presence of EcPV2 in neoplastic cells.

In summary, this research provides more insights into the correlation between EcPV2 and a subset of genital squamous cell carcinomas in horses. Using a sensitive ISH method, it was identified that EcPV2 is present in a large number of SCC samples and supports the hypothesis that EcPV2 contributes to the formation of these malignancies. Moreover, it’s also identified that the virus is present in the metastatic cells from the primary tumor site, indicating a stable expression of the virus’ oncogenes.