Expression and Significances of G-Protein-Coupled Receptor Kinase 3 in Hepatocellular Carcinoma

Objective: To investigate expression, clinical, pathologic and prognostic significances of G-protein-coupled receptor kinase 3 (GRK3) in hepatocellular carcinoma (HCC). Materials and Methods: Expression of GRK3 was detected using Western blotting and tissue microarray-based immunohistochemical staining in 8 and 395 patients (training set: n=164; validation set: n=231) with HCC underwent hepatectomy, respectively. GRK3 expression and its associations with cliniopathologic variables and tumor-specific survival were evaluated. Results: Expression of GRK3 was lower in tumor than in non-tumor tissues from 4 out of 8 patients. In the training set, the H-score of tumoral GRK3 staining was much lower than that in adjacent non-tumor liver tissues. In addition, GRK3 was associated with tumor-node-metastasis (TNM) stage and serum α-fetoprotein (AFP) level. Patients with high GRK3 tumors were found to carry significantly better tumor-specific survival, compared with those with low GRK3 ones. Furthermore, GRK3 was identified as one of independent predictors of favorable prognosis, adjusted for clinicopathologic parameters. Importantly, these results were further validated in the independent validation set. In all patients and 7 out of 10 subgroups, GRK3 was also revealed to be prognostic. Conclusions: GRK3 is down-regulated and predicts good prognosis in HCC. Therefore, GRK3 might function as a tumor suppressor gene in HCC.