Assessment of potential clinical approaches for the expression of prolactin receptor (PRL-R) and vascular endothelial growth factor (VEGF) in various feline mammary gland tumors

Feline mammary gland tumors are a serious health concern, resulting in a significant reduction in the animal’s lifespan and a decrease in the overall quality of life. Malignant tumors often lead to recurrences and metastases. Among endogenous factors that may influence the development or progression of mammary neoplasia, prolactin (PRL) and vascular endothelial growth factor (VEGF) appear to be of crucial importance. This study involved 60 queens with surgically removed mammary gland tumors, which were subsequently stained with hematoxylin and eosin (HE) and immunofluorescence to assess the expression of PRL and VEGF. Variables considered during analyses included the time of ovariohysterectomy, inflammation severity and clinical tumor behavior. The VEGF expression in tumors exhibited an increase in malignant cases, providing evidence of heightened angiogenesis. A lack of differences in the overall expression of PRL receptor was found between tumor types. However, the lower expression of PRL receptor in tumors with increased inflammation may suggest PRL’s immunomodulating functions in feline malignant neoplastic tumors. Interestingly, the absence of positive influence of gonadectomy on tumor behavior highlights the need for further research regarding this form of prevention. High expression of PRL receptor and VEGF only in distant metastases may prompt future research on the proangiogenic function of PRL in feline mammary gland tumors.