MUC1 expression in pulmonary metastatic tumors: a comparison of primary lung cancer

MUC1 expression has been described as a predictor for tumor progression and worsening of prognosis in various human neoplasms. However, little is known about the role of MUC1 expression in pulmonary metastatic tumors. The aim of this study is to examine the clinicopathological significance of MUC1 expression in pulmonary metastatic tumors (PMT). One hundred forty-seven patients with PMT who underwent (18)F-FDG PET before metastasectomy were included in this study. Tumor sections were stained by immunohistochemistry for MUC1, glucose transporter 1 (Glut1), hypoxia-inducible-1α (HIF-1α) and vascular endothelial growth factor (VEGF). (18)F-FDG uptake and the expression of these biomarkers were correlated in primary lung cancer. MUC1 expression pattern was classified into high-grade polarized expression (HP), low-grade polarized expression (LP), or depolarized expression (DP) group. Of 147 patients, HP, LP and DP group were 9 (6%), 114 (78%) and 24 (16%), respectively. The expression of Glut1, HIF-1αand VEGF, and (18)F-FDG uptake were significantly higher in DP group than HP or LP groups. MUC1 expression with HP and DP pattern was significantly higher in primary lung cancer than in PMT, whereas, MUC1 expression with LP pattern yielded a significantly high positive rate in PMT. LP group was recognized in the majority of patients with pulmonary metastatic adenocarcinoma, especially colon cancer, whereas, HP group was significantly low in pulmonary metastatic adenocarcinoma as compared with primary adenocarcinoma. Polarized MUC1 has a different expression pattern between primary and metastatic tumors with adenocarcinoma, and depolarized MUC1 is closely associated with glucose metabolism and hypoxia.