Prognostic significance of circumferential cell surface immunoreactivity of glypican-3 in hepatocellular carcinoma.
BACKGROUND
GC33 is a recently developed monoclonal antibody against human glypican-3 (GPC3), which is significantly upregulated in hepatocellular carcinoma (HCC). GC33 recognizes a GPC3 ectodomain and shows significant antitumour activity in vivo. Thus, humanized GC33 antibody may be a promising tool for treating HCC having cell surface GPC3 expression.


OBJECTIVE
This study aims to determine the specificity, subcellular localization and prognostic impact of GPC3 immunoreactivity detected by GC33 in HCC clinical specimens.


METHODS
Immunohistochemical analysis was performed for 194 cases of resected HCC and prognostic analysis was performed for 185 eligible cases. Two antigen retrieval methods (autoclave and protease pretreatments) were used for immunohistochemistry and compared. The immunoscore system reflecting circumferential membranous GPC3 immunoreactivity was developed using either the autoclave or protease methods. The GPC3 mRNA level was analysed by quantitative real-time reverse transcription-polymerase chain reaction.


RESULTS
GC33 immunostaining after autoclave is a sensitive method and revealed the GPC3 expression (≥20% of tumour cells) in the majority (77%) of HCC samples tested. Alternatively, protease pretreatment showed lower sensitivity, but was superior for evaluating the intensity and subcellular localization of GPC3. Correlation between immunoscores and the GPC3 mRNA level was also confirmed. Subsequent clinicopathological analysis revealed worse prognoses in HCC patients with circumferential membranous GPC3 immunoreactivity. For HCC patients with hepatitis C virus (HCV) infection in particular, the high membranous GPC3 immunoreactivity was an independent prognostic factor for disease-free survival.


CONCLUSIONS
Circumferential membranous GPC3 immunoreactivity in HCC indicates poorer prognosis particularly in patients with HCV infection.
Section of Oncopathology and Regenerative Biology, Department of Pathology, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan.
Kenji
K
Yorita
Nobuyasu
N
Takahashi
Hirotake
H
Takai
Atsuhiko
A
Kato
Masami
M
Suzuki
Takahiro
T
Ishiguro
Toshihiko
T
Ohtomo
Koki
K
Nagaike
Kazuhiro
K
Kondo
Kazuo
K
Chijiiwa
Hiroaki
H
Kataoka
D014408:Biomarkers, Tumor / Q000032:analysis* / Q000235:genetics; D001706:Biopsy; D006528:Carcinoma, Hepatocellular / Q000737:chemistry* / Q000235:genetics / Q000401:mortality / Q000628:therapy / Q000821:virology; D002462:Cell Membrane / Q000737:chemistry*; D016009:Chi-Square Distribution; D018572:Disease-Free Survival; D005260:Female; D053673:Glypicans / Q000032:analysis* / Q000235:genetics; D016174:Hepacivirus / Q000302:isolation & purification; D006801:Humans; D007150:Immunohistochemistry; D007564:Japan; D053208:Kaplan-Meier Estimate; D008113:Liver Neoplasms / Q000737:chemistry* / Q000235:genetics / Q000401:mortality / Q000628:therapy / Q000821:virology; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome
D014408:Biomarkers, Tumor; C105937:GPC3 protein, human; D053673:Glypicans; D012333:RNA, Messenger