Subtype-dependent difference of glucose transporter 1 and hexokinase II expression in craniopharyngioma: an immunohistochemical study

Papillary craniopharyngiomas are characterized by the BRAF V600E mutation. Enhancement of glucose metabolism may be involved in the downstream of the BRAF V600E mutation in many types of tumors. Glucose metabolism was investigated in craniopharyngioma using immunohistochemical analysis. The study included 29 cases of craniopharyngioma (18 adamantinomatous type [ACP], 11 papillary type [PCP]). Immunohistochemical analysis was performed with anti-glucose transporter-1 (GLUT-1), anti-hexokinase-II (HK-II), anti-BRAF V600E, and anti-beta-catenin antibodies. Expressions of GLUT-1 and HK-II were evaluated using a semiquantitative 4-tiered scale as 0, 1+, 2+, 3+, and divided into negative (0 or 1+) or positive (2+ or 3+) group. GLUT-1 expression level was significantly higher in PCPs than ACPs (0, 1+, 2+, 3+ = 2, 12, 4, 0 cases in ACP, respectively, 0, 1+, 2+, 3+ = 0, 2, 5, 4 in PCP, p = 0.001), and most PCPs were classified into positive group (positive rate, 22.2% [4/18] in ACP, 81.8% [9/11] in PCP; p = 0.003). HK-II expression was also conspicuous in PCPs (0, 1+, 2+, 3+ = 7, 9, 2, 0 cases in ACP, 0, 3, 3, 5 in PCP; p = 0.001), and most of them divided into positive group (positive rate, 11.1% [2/18] in ACP, 72.7% [8/11] in PCP; p = 0.001). Expression patterns of BRAF V600E and beta-catenin reflected the clinicopathological subtypes. Both GLUT-1 and HK-II expressions were prominent in PCP. Glucose metabolism might be more enhanced in PCP than ACP. PCP may use the glucose metabolic system downstream of the BRAF V600E mutant protein.