mal and malignant epithelial cells and several other cell The c-met proto-oncogene encodes the tyrosine kinase types, including endothelial cells and melanocytes. 4,5 receptor for hepatocyte growth factor (HGF), a potent
It has been reported that the expression of c-Met is enmitogen and motogen for epithelial cells. Because of its hanced in thyroid, 6 gastric, 7 colorectal, 8 and prostatic canprofound effects on cell growth and motility, HGF may cers, 9 which suggests that an altered expression of c-Met may be important in the development of cancer metastases be involved in cancer development. With respect to HCC, few in hepatocellular carcinoma (HCC). In this study, we exreports have been written on c-met expression. Prat et al. 10 amined HGF concentration and expression of the c-met have reported the expression of c-met protein in 11 of 14 proto-oncogene product (c-Met) in 62 patients with HCC HCCs using immunofluorescence, and Boix et al. 11 have reto determine the relationship between the level of exported that overexpression of c-met messenger RNA (mRNA) pression and clinicopathological features, and patient was detected in 8 of 18 HCCs. Suzuki et al. have shown outcome following hepatectomy. Western blotting was
that c-met protein was correlated with differentiation of HCC used to examine the c-Met expression, and HGF concencells. 12 However, the relationship between c-Met expression tration in tumors was measured using an enzyme-linked and tumor development, metastases, and patient outcome immunosorbent assay. c-Met was found to be overexhas not been clarified.
pressed in HCC compared with nontumorous liver tissue
In this study, we examined c-Met expression and HGF con-
P Γ΅ .01), and correlated with an increased incidence of centration in HCC and in nontumorous hepatic tissue, and intrahepatic metastases (P Γ
.039). Patients were diinvestigated whether HGF and c-Met were associated with vided into two groups: low c-Met HCC and high c-Met clinicopathological features of HCC and patient outcome after HCC. Patients with high c-Met HCC had a significantly hepatectomy. shorter 5-year survival than patients with low c-Met HCC (33.5% vs. 80.3%, respectively; P Γ΅ .05). However, PATIENTS AND METHODS there was no correlation between HGF concentration in the tumor tissue and clinicopathological factors and Patients and Tumor Samples. Sixty-two patients with HCC who patient survival. These results indicate that the expresunderwent curative surgical resections 13 between September 1987 sion of c-Met played an important role in tumor growth and November 1992 at our hospital were included in the study. The and metastases in patients who underwent hepatectomy mean age of the patients was 60 years (range, 35-75 years), 92% of whom were men. None had apparent distant metastases. None of the for HCC. (HEPATOLOGY 1997;25:619-623.)
patients received palliative treatment such as percutaneous ethanol injection and/or transcatheter arterial embolization before surgical Hepatocyte growth factor (HGF) is a pleiotropic polypepresection. Chronic liver disease was noted as follows: cirrhosis, 51 tide growth factor with a number of biological activities, in-(82.3%); chronic hepatitis, fibrosis, or both, 6 (9.6%). Twelve patients (19%) indicated the presence of hepatitis B surface antigen, and 23 cluding mitogenic, motogenic, and/or morphogenic proper-(37%) showed anti-hepatitis B surface antibody and/or anti-hepatitis ties, in a variety of epithelial tissues. Because HGF is a potent core antibody by enzyme-linked immunosorbent assay. Fifty-five of mitogen in hepatocytes, its involvement in the growth and 62 patients were tested with a second-generation hepatitis C virus development of metastases in hepatocellular carcinoma antibody (Ortho Diagnostics, Raritan, NJ), and 70.9% revealed the (HCC) is suspected. Recently, purified HGF has been shown presence of hepatitis C virus. A tumor sample and nontumorous to stimulate invasive characteristics in various cancer cells tissue were obtained immediately after the liver resection and were in vitro, 1,2 therefore, it is possible that HGF plays an imsnap-frozen in liquid nitrogen and stored at 080ΠC. Histological sec- portant role in the establishment of intrahepatic metastases tions were prepared and stained with hematoxylin-eosin. The cyto- and distant metastases in patients with HCC. logic features of the tumors were classified into three groups: welldifferentiated, moderately differentiated, and poorly differentiated. 13 The receptor for HGF is a tyrosine kinase receptor encoded
The size of tumor, vascular invasion, and the presence of intrahepatic by the c-met proto-oncogene. This protein is a heterodimer of metastases were also evaluated. 13 two disulfide-linked chains; 50-kd a and 145-kd b subunits Cell Lines. Human hepatoma cell lines including HepG2, Hep3B, are generated by cleavage of a single 190-kd precursor. 3 The Huh-7, and PLC were grown in Dulbecco's modified Eagle medium b unit has both extracellular and intracellular domains, and (Sigma, St. Louis, MO) supplemented with 10% fetal bovine serum, the intracellular domain has tyrosine kinase activity. The cpenicillin (50 units/mL), and streptomycin sulfate (50 mg/mL) unless met proto-oncogene product (c-Met) is expressed in both norotherwise specified. These cell lines were used to estimate the expres- sion level of c-Met in tumor and nontumorous tissue.
Western Blotting. Cells as well as 0.5 g of frozen tissue were homogenized and extracted with 1.5 mL of RIPA (phosphate-buffered Abbreviations: HGF, hepatocyte growth factor; HCC, hepatocellular carcinoma; mRNA, saline, 1% NP40, 0.5% sodium deoxycholate, 0.1% sodium dodecyl messenger RNA.