Tumor Cells and Microenvironmental Interaction in Natural Course of Canine Transmissible Venereal Tumor

Abstract

Canine transmissible venereal tumors (CTVT) is a naturally occurring tumor that is mostly transmitted between dogs through coitus. This study aims to investigate the effect of CTVT on molecular expression and disease progression by studying the tumor microenvironment (TME). For this purpose, biopsy samples taken from ten female dogs were evaluated histopathologically and CTVT was diagnosed. The expression of markers such as CD163, CD68, CD44, TGF-beta and bFGF was evaluated by immunoperoxidase tests. Histopathologically, CTVT cells exhibited pleomorphism, ranging from round to polygonal. Some cells exhibited prominent vacuoles and hypochromatic nuclei, while others exhibited hyperchromatic nuclei containing mitotic figures within the thin fibrovascular wall. Immunohistochemically, TGF-beta and CD44 expression was higher in CTVT cells compared to CD68 and bFGF, while bFGF expression was higher in fibrocytes and spindle cells compared to other markers. The results indicate that CD44 and TGF-beta may play a pivotal role in fibrovascular processes, CD163 and CD68 may facilitate interactions between stromal components and mesenchymal cells, and bFGF, TGF-beta and CD68 may contribute to the arrest of tumoral progression and the initiation of the regression phase. These findings underscore the necessity for further studies to elucidate the role of markers at different stages of CTVT progression.