P-glycoprotein expression affects 18F-fluorodeoxyglucose accumulation in hepatocellular carcinoma in vivo and in vitro.
18F-fluorodeoxyglucose (FDG) uptake in hepatocellular carcinoma (HCC) is associated with tumor differentiation and expression of P-glycoprotein (P-gp), a drug efflux pump that plays an important role in chemoresistance. The aim of the study was to clarify the factors that affects FDG uptake in HCC in vivo and in vitro. The standardized uptake value (SUV) and the tumor to non-tumor SUV ratio (TNR) for FDG uptake in HCC in vivo was determined by FDG-PET in 28 patients. Expression levels of glucose transporter-1 (GLUT-1), GLUT-2 and type II hexokinase (HK-II) were examined immunohistochemically in resected specimens. The glucose-6-phosphatase (G-6-Pase) activity was determined in tissue homogenates. In vitro, PLC/PRF/5 cells and doxorubicin-resistant PLC/DOR cells were used to examine the effect of P-gp on FDG uptake. The effects of two P-gp inhibitors, verapamil and cepharanthine, on accumulation of FDG were also examined. in vivo, GLUT-1 expression was low in HCCs, but was significantly higher in poorly differentiated HCCs than in moderately differentiated HCCs (P=0.043) and was positively correlated with SUV (r=0.75, P<0.0001) and TNR (r=0.7, P<0.0001). GLUT-2 and HK-II expression and G-6-Pase activity were not correlated with tumor differentiation, SUV or TNR. P-gp was over-expressed in PLC/DOR cells, and accumulation of FDG was significantly higher in PLC/PRF/5 cells than in PLC/DOR cells (P=0.04). Verapamil and cepharanthine restored FDG uptake in PLC/DOR cells, but not in PLC/PRF/5 cells. Collectively, our results show that FDG uptake in HCC is weakly correlated with GLUT-1 expression, and that FDG could be a substrate of P-gp, which may act as an efflux pump to reduce FDG accumulation.
Department of Surgery, Graduate School of Medicine Kyoto University, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan.
Satoru
S
Seo
Etsuro
E
Hatano
Tatsuya
T
Higashi
Akio
A
Nakajima
Yuji
Y
Nakamoto
Masaharu
M
Tada
Nobuyuki
N
Tamaki
Keiko
K
Iwaisako
Koji
K
Kitamura
Iwao
I
Ikai
Shinji
S
Uemoto
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D006528:Carcinoma, Hepatocellular / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000473:pathology; D002454:Cell Differentiation; D018450:Disease Progression; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism / Q000493:pharmacokinetics*; D051272:Glucose Transporter Type 1 / Q000378:metabolism; D051273:Glucose Transporter Type 2 / Q000378:metabolism; D005952:Glucose-6-Phosphatase / Q000378:metabolism; D006593:Hexokinase / Q000378:metabolism; D006801:Humans; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000473:pathology; D008954:Models, Biological; D011877:Radionuclide Imaging; D014407:Tumor Cells, Cultured; D014700:Verapamil / Q000494:pharmacology
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D002121:Calcium Channel Blockers; D051272:Glucose Transporter Type 1; D051273:Glucose Transporter Type 2; D019788:Fluorodeoxyglucose F18; D014700:Verapamil; D006593:Hexokinase; D005952:Glucose-6-Phosphatase