Immunohistochemical characterization of immune cell and metabolic markers in canine prostate carcinoma

Canine prostate carcinoma (cPCA) is an aggressive malignancy with limited prognostic markers. This study aimed to comprehensively characterize immune-cell infiltration, glycolysis, hypoxia and oncogenic markers in cPCA and assess their clinical relevance. Tumour tissues from 26 dogs with cPCA and hyperplastic prostate tissues from seven dogs were analysed using immunohistochemistry. Five immune cell markers (CD3, CD20, CD8, Foxp3 and CD204) were quantitatively assessed, and the amounts of immunolabelling of monocarboxylate transporter 4 (MCT4), glucose transporter 1 (GLUT1), human epidermal growth factor receptor 2 and Ki-67 were evaluated through established scoring methods. Associations between progression-free survival and overall survival were analysed using univariate Cox regression. All tumours were infiltrated by multiple immune-cell subsets, characterized by marked intertumoral heterogeneity. Immune-cell densities were generally higher in cPCA than in hyperplastic prostate tissue. Compared with hyperplastic prostate tissue, cPCA showed lower MCT4 and higher GLUT1 expression. No significant associations were observed between immune-cell density or marker expression and clinical outcomes. The findings suggest that cPCA has widespread immune-cell infiltration and distinct metabolic features; however, individual immunohistochemical markers alone were insufficient to predict clinical outcomes.