Granulin-epithelin precursor overexpression promotes growth and invasion of hepatocellular carcinoma.
OBJECTIVE
Granulin-epithelin precursor (GEP) is a novel growth factor. Our earlier cDNA microarray study indicated that GEP was overexpressed in hepatocellular carcinoma (HCC). The aim of this study was to investigate the clinical significance of GEP expression and its potential as a therapeutic target in HCC.


METHODS
A total of 110 pairs of HCCs and adjacent nontumor liver tissues, and 22 normal liver tissues were examined. The GEP RNA level was examined by quantitative reverse transcription-PCR, and protein localization by immunohistochemistry. The GEP function was examined by transfection experiments.


RESULTS
The RNA levels of the HCCs were significantly higher than those of the nontumor liver tissues and normal livers (P <0.001). GEP protein staining was observed in tumor cytoplasm, and the GEP protein levels of the HCCs were also significantly higher than those of the nontumor liver tissues and normal livers (P <0.001). The majority of HCCs demonstrated up-regulation of GEP protein compared with their adjacent liver tissues [79 (71.8%) of 110]. Positive correlation of GEP RNA with protein levels was observed in HCCs (P <0.01). Strong GEP expression was associated with large HCCs, venous infiltration, and early intrahepatic recurrence (P <0.05). Functional studies on the HCC cell line Hep3B demonstrated that reduction of GEP protein levels resulted in decreased cell proliferation rates, tumor invasion ability, anchorage-independent growth in soft agar, and tumorigenicity in nude mice (P <0.05).


CONCLUSIONS
GEP is an important factor for HCC growth, invasion, and metastasis. GEP has the potential to serve as a tumor marker and therapeutic target.
Cheung
Siu Tim
ST
Centre for the Study of Liver Disease and Departments of Surgery and Pathology, The University of Hong Kong, Pokfulam, Hong Kong, China. stcheung@hkucc.hku.hk
Wong
San Yu
SY
Leung
Ka Ling
KL
Chen
Xin
X
So
Samuel
S
Ng
Irene O
IO
Fan
Sheung Tat
ST
D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D018076:DNA, Complementary / Q000378:metabolism; D000077155:Granulins; D006801:Humans; D007150:Immunohistochemistry; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis*; D008099:Liver / Q000378:metabolism; D008113:Liver Neoplasms / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D008819:Mice, Nude; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D009368:Neoplasm Transplantation; D020411:Oligonucleotide Array Sequence Analysis; D000077153:Progranulins; D012313:RNA / Q000378:metabolism; D012008:Recurrence; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014162:Transfection; D015854:Up-Regulation
D018076:DNA, Complementary; D000077155:Granulins; D036341:Intercellular Signaling Peptides and Proteins; D000077153:Progranulins; D012313:RNA