ABSTRACT
INTRODUCTION: Due to individual deviations in tumor tissue uptake, the role of [18F]fluorodeoxyglucose ([18F]FDG) positron emission tomography (PET) in hepatocellular carcinoma (HCC) diagnosis is limited. ß-Hydroxy ß-methylglutaryl-CoA reductase degradation 1 (HRD1) plays a key role in clearing misfolded proteins. This study is aimed to investigate the role and mechanism of HRD1 in [18F]FDG uptake for the diagnosis of HCC. METHODS: HRD1 expression level was detected using immunohistochemical (IHC) staining in 9 HCC patients. [18F]FDG PET/CT scans were conducted before treatment. [18F]FDG uptakes in HRD1 overexpressed and knockdown transgenic models were measured by γ-counter and microPET imaging. The GLUT1-HRD1 complex was examined by co-immunoprecipitation and IHC assays. GLUT1 expression in different cell lines, xenograft models and HCC patients was evaluated by Western blot and IHC assays. RESULTS: HRD1 was highly expressed in the HCC tumors of patients with low [18F]FDG uptake, while the HRD1 expression was obviously low in the higher [18F]FDG uptake group. Both in vitro and in vivo studies found that HRD1 significantly inhibited [18F]FDG uptake in HCC Huh7 cell lines and animal models. Furthermore, the co-location and interaction of HRD1 with GLUT1 were detected, and the results also indicate that HRD1 could induce the degradation of GLUT1 in vitro and in vivo. CONCLUSION: HRD1 inhibits the high uptake of [18F]FDG in HCC tumor cells by inducing degradation of GLUT1, which leads to decreased diagnostic efficiency of [18F]FDG PET imaging for HCC. ADVANCES IN KNOWLEDGE: This study suggests that HRD1 inhibits the high uptake of [18F]FDG in HCC tumor by inducing degradation of GLUT1. IMPLICATIONS FOR PATIENT CARE: HCC diagnosis with [18F]FDG PET should be accompanied by determination of HRD1 expression, and patients with high tumor HRD1 expression might be unsuitable for [18F]FDG PET.
