Differential Expression of Glut1 in Pulmonary Neuroendocrine Tumors: Correlation with Histological Grade

ABSTRACT

BACKGROUND: Increased glucose uptake, a process that is mediated by glucose transporter (Glut1) proteins, is an important metabolic feature in a variety of cancer cells. The overexpression of Glut1 in human cancers is known to be related to a variety of histopathological parameters, including histological grade, proliferation rate, and lymphatic invasion. The principal objective of this study was to evaluate Glut1 expression in the spectrum of pulmonary neuroendocrine (NE) tumors including typical carcinoid tumor (TC), atypical carcinoid tumor (AC), large cell neuroendocrine carcinoma (LCNEC), and small cell carcinoma (SCC), and to characterize the relationship between Glut1 expression and the histologic grade of NE tumors. METHODS: 19 TC, 7 AC, 13 LCNEC, and 6 SCC patients were included in this study. The percentages of Glut1-positive tumor cells in these patients were determined. For statistical analysis, Glut1 expression was subdivided into a Glut1-low expression group (0-30%) and a Glut1-high expression group (31-90%). RESULTS: In our subgroup analyses, the histological grade of pulmonary neuroendocrine (NE) tumors was significantly correlated with Glut1 expression; TC (n=19, 3.6+/-4.2%), AC (n=7, 20.0+/-4.9%), LCNEC (n=13, 60.0+/-21.1%), and SCC (n=6, 74.2+/-16.9%). Glut1-high expression was significantly associated with high-grade NE tumors such as LCNEC and SCC (n=19, 62.6+/-21.0%) (p=0.000). CONCLUSIONS: The results of this study appear to indicate that Glut1 overexpression is a consistent feature of high-grade NE lung tumors.