Association of glycolysis-related protein expression with prognosis in Canine Pulmonary Adenocarcinoma

Canine pulmonary adenocarcinoma (CPAC) is a rare, aggressive tumor with no established prognostic molecular biomarkers. The expression of monocarboxylate transporter 4 (MCT4) and glucose transporter 1 (GLUT1), key glycolysis-related proteins, is induced by hypoxia and is generally associated with poor prognosis in human pulmonary adenocarcinoma; however, their clinical significance in dogs remains unclear. This study investigated the expression of MCT4 and GLUT1 in 61 CPAC cases. Immunohistochemistry revealed significantly higher MCT4 and GLUT1 expression in tumors compared with normal lung tissues. High expression of both proteins was associated with lymph node metastasis. Kaplan-Meier analysis showed that high MCT4 expression was associated with prolonged overall survival, while GLUT1 showed no prognostic impact. However, MCT4 was not retained as an independent prognostic factor in multivariable Cox proportional hazards analysis. These results suggest that MCT4 and GLUT1 are upregulated in CPAC and may have distinct biological and clinical significance compared with human pulmonary adenocarcinoma.