10.1245/ASO.2006.11.035
Annals of Surgical Oncology 13:159-167 (2006)
© 2006 Society of Surgical Oncology
Hepatoma-Derived Growth Factor Is a Novel Prognostic Factor for Hepatocellular Carcinoma
Kenya Yoshida, MD1,
Yasuhiko Tomita, MD2,
Yorihide Okuda, MD1,
Shinji Yamamoto, MD3,
Hirayuki Enomoto, MD1,
Hirokazu Uyama, MD1,
Hiroaki Ito, MD1,
Yoshihiko Hoshida, MD2,
Katsuyuki Aozasa, MD2,
Hiroaki Nagano, MD3,
Masato Sakon, MD3,
Ichiro Kawase, MD1,
Morito Monden, MD3 and
Hideji Nakamura, MD1
1 Department of Molecular Medicine, Osaka University Graduate School of Medicine, Yamada-oka 2-2, Suita, 565-0871 Osaka, Japan
2 Department of Pathology, Osaka University Graduate School of Medicine, Yamada-oka 2-2, Suita, 565-0871 Osaka, Japan
3 Department of Surgery and Clinical Oncology, Osaka University Graduate School of Medicine, Yamada-oka 2-2, Suita, 565-0871 Osaka, Japan
Correspondence: Address correspondence and reprint requests to: Hideji Nakamura, MD, Division of Hepatobiliary and Pancreatic Medicine, Department of Internal Medicine, Hyogo College of Medicine. Mukogawa-cho 1-1, Nishinomiya 663-8501, Hyogo, Japan; E-mail: nakamura{at}hyo-med.ac.jp.
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ABSTRACT
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Background: Hepatoma-derived growth factor (HDGF) is involved in hepatocarcinogenesis, as well as in liver development and regeneration. This study investigated the correlation of HDGF expression with differentiation and prognosis of hepatocellular carcinoma (HCC).
Methods: HDGF expression in 100 patients with HCC (81 men and 19 women) with ages ranging from 34 to 81 years (median, 61 years) receiving surgical treatment was analyzed by immunohistochemistry. HDGF messenger RNA expression was evaluated in 10 cases by reverse transcription-polymerase chain reaction. The immunostaining pattern in HCCs was categorized as a positive HDGF index (showing positive staining in >90% of tumor cells in both nucleus and cytoplasm) or a negative HDGF index (all others).
Results: Twenty-seven cases (27%) showed a positive and 73 (73%) showed a negative HDGF index. HDGF messenger RNA expression was significantly higher in four cases with a positive HDGF index than in six with a negative index. Cases with well-differentiated histological characteristics showed a higher rate of positive HDGF index than those with a poorly differentiated subtype. Univariate and multivariate analysis revealed significantly poorer disease-free and overall survivals in patients with a positive HDGF index compared with patients with a negative index.
Conclusions: These findings suggest the potential utility of HDGF immunohistochemistry in determining the prognosis of HCC.
Key Words: Hepatoma-derived growth factor Hepatocellular carcinoma Prognosis Recurrence
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INTRODUCTION
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Hepatocellular carcinoma (HCC) is one of the most prevalent fatal cancers worldwide, especially in Asia and Africa.1 Surgical resection offers the chance of a cure, but the prognosis remains poor even in curatively resected cases, mainly because of the high recurrence rate.24 The recurrence rate of HCC after all forms of therapy other than transplantation is 15% to 20% per year and is due to new lesions but not to local recurrence.24 Hence, if surgeons could predict or identify patients at high risk for early recurrence, then these patients might be better treated with nonresection therapy. Therefore, the prognostic factors for recurrence and survival are important to help guide clinicians in the management of patients, in the assessment of long-term prognosis, and in the selection of the treatment modality for HCC. Conventionally, the assessment of prognosis in HCC depends on staging by the tumor-node-metastasis system, including tumor morphology and portal vein thrombosis, and the serum level of alfa fetoprotein (AFP).26 Recently, new pathologic and biological factors, including proliferating cell nuclear antigen, Ki-67, and the expression of several genes, including oncogenes and growth factors, have been shown to predict the prognosis of HCC.7
Hepatoma-derived growth factor (HDGF) is a heparin-binding protein purified from the conditioned media of HuH-7 hepatoma cells; it proliferates autonomously in a serum-free chemically defined medium.8,9 HDGF is the first member of the HDGF family of proteins to contain a well-conserved N-terminal amino acid sequence, which is called the hath (homologous to amino terminus of HDGF) region.9,10 HDGF translocates to the nucleus via nuclear localization signals, and its nuclear translocation is essential for the induction of cell growth activity.11,12 HDGF has mitogenic activity for some HCC cells, in addition to fibroblasts, endothelial cells, vascular smooth muscle cells, and fetal hepatocytes.8,9,1217 HDGF antisense oligonucleotides suppress the proliferation of hepatoma cells that express HDGF endogenously.15 HDGF was more abundantly expressed in HCC than in the nontumorous adjacent liver tissues in human and murine samples.18 HDGF is a unique nuclear/growth factor that may play an important role in the development and progression of HCC. In this study, the expression level of HDGF in HCC was examined by reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemical analysis, and its correlation with recurrence and survival in patients with HCC was evaluated.
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PATIENTS AND METHODS
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Patients and Tissue Samples
One hundred patients who received curative resection for primary HCC at the Gastroenterological Surgery Division, Osaka University Hospital, from October 1987 to January 2001 were analyzed for this study. There were 81 men and 19 women with ages ranging from 34 to 81 years (median, 61 years). Sixteen patients were positive for hepatitis B virus surface antigen, and 66 were positive for hepatitis C virus antibody. Preoperative diagnostic imaging examinations, including ultrasonography, computed tomographic scan, and angiography, were performed in all patients. Liver function was assessed according to the Child-Pugh classification. Types of surgery used were limited resection in 46 patients, subsegmentectomy in 24, segmentectomy in 17, lobectomy in 12, and extended lobectomy in 1.
Surgically resected specimens were fixed in 10% formalin, macroscopically examined, and sliced at 5-mm intervals. The section containing the largest volume of HCC was processed for paraffin embedding. Four to 43 blocks per case were obtained. Histological sections cut at 4-µm thicknesses were stained with hematoxylin and eosin and reviewed by two of the authors (K.Y. and Y.T.) to determine the following categories: differentiation of tumor cells based on the criteria proposed by Edmondson and Steiner19 (I, well differentiated; II, moderately differentiated; III, poorly differentiated; IV, undifferentiated), pattern of growth (expansive or infiltrative), formation of a fibrous capsule around the tumor, portal vein invasion, tumor multiplicity, and positivity for the surgical margin. The surgical margin was identified as positive when tumor cells were present at the edge. The degree of inflammation and fibrosis in noncancerous hepatic tissues was shown as the histological activity index score.20 The representative one slide per case was used for HDGF immunohistochemistry.
After resection, all patients were followed up by monitoring serum AFP, ultrasonography, and contrast-enhanced computed tomographic scan every 1 and 3 months; for suspicious cases, angiography was performed to verify the recurrence. The follow-up periods for survivors ranged from 2 to 128 months (median, 43 months) after surgery.
Anti-Human HDGF Antibody and Western Blotting
Rabbit polyclonal antibody was raised against C-terminal amino acids (amino acids 231240) of the human HDGF sequence. The specificity and sensitivity of the antibody have been described previously.10,13 Protein samples were extracted from human cell lines, HepG2, PLC/PRF/5, HuH7, and HT29 by using CelLytic-M Mammalian Cell Lysis/Extraction Reagent (Sigma, St. Louis, MO). Ten micrograms of cell lysates, along with recombinant HDGF, was electrophoresed in sodium dodecyl sulfate polyacrylamide gel and transblotted onto polyvinylidene difluoride transfer membranes (Millipore, Bedford, MA). The blotted membranes were reacted with an affinity-purified polyclonal antiC-terminus of HDGF antibody generated by rabbit at a dilution of 1/10,000 and then visualized with an electrochemiluminescence detection system (Amersham Pharmacia Biotech, Buckinghamshire, UK).
Immunohistochemical Analysis
Immunohistochemical staining was performed on formalin-fixed, paraffin-embedded sections by using the avidin-biotin complex method. Antigen retrieval was performed with microwave treatment (5 minutes, three times) in 10 mM of citrate buffer (pH 6.0). Anti-HDGF antibody was used as the primary antibody at a dilution of 1/5000. Sections were lightly counterstained with methyl green. Positive staining in the bile ducts in the noncancerous lesions was used as the internal positive control. Stained sections were evaluated in a blinded manner without prior knowledge of the clinicopathologic parameters. The counting of immunohistochemically positive cells was performed by hand under a microscope. For each case, all the HCC area in the slides was carefully examined, and the HDGF-positive rate was determined.
The HDGF expression pattern was independently evaluated for the nucleus and cytoplasm; cells showing a staining intensity similar to or stronger than that in bile ducts in the nucleus or cytoplasm were regarded as nucleus positive or cytoplasm positive, respectively. Samples with >90% of tumor cells that expressed positive immunoreactivity both for nucleus and cytoplasm were regarded as HDGF index positive, and others were regarded as HDGF index negative.
Quantitative RT-PCR Analysis of HDGF
Total RNA was extracted from fresh-frozen samples in 18 cases of HCC with TRIzol reagent (Invitrogen, Carlsbad, CA). Ten micrograms of deoxyribonuclease Itreated total RNA was used for RT with Superscript II (Invitrogen). An aliquot representing 100 ng of input RNA was amplified by quantitative real-time PCR by using a TaqMan PCR Reagent Kit (Applied Biosystems, Foster City, CA) with the ABI PRISM 7700 Sequence Detection System (Applied Biosystems) as follows: 50°C for 2 minutes, 95°C for 10 minutes, and 40 cycles at 95°C for 15 seconds and 60°C for 1 minute. The following were used for amplification of ß-actin: forward primer, 5'-TCACCCACACTGTGCCCATCTACGA-3'; reverse primer, 5'-CAGCGGAACCGCTCATTCGCCAATGG-3'; and probe, 5'6-carboxy-fluorescein (FAM)-ATGCCC6-carboxytetramethylrhodamine (TAMRA)-CCCCCATGCCATCCTGCGTp-3'. The forward primer 5'-AAGTTTGGCAAGCCCAACA-3', reverse primer 5'-GGCTCTTCCACACAGCTCTTT-3', and probe 5'-FAM-AACCCTACTGTCAAGGCTTCCGGCT-TAMRA-3' were used for HDGF. RNA extracted from an HCC sample in one case was used as a standard. After RT, standard complementary DNA (cDNA) was serially diluted to obtain five standard solutions for a use in PCR reaction to generate the reference curve. The relative amount of cDNA in each sample was measured by interpolation in the standard curve, and then the relative ratio of HDGF/ß-actin expression was calculated for each HCC sample.
Statistics
Statistical analysis was performed by using JMP (SAS Institute Inc., Cary, NC). The correlation between the expression level of HDGF at quantitative RT-PCR and immunohistochemistry was evaluated by one-way analysis of variance. Correlations between the HDGF expression level by immunohistochemistry and the clinicopathologic parameters were evaluated by
2 test and Fishers exact probability test. The overall and disease-free survival rates were calculated by using Kaplan-Meier methods,21 and differences in survival curves were analyzed by the log-rank test. Independent prognostic factors were analyzed by the Cox proportional hazards regression model in a stepwise manner.22 P < .05 was considered statistically significant.
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RESULTS
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Western Blotting
Western blotting by using HDGF antibody showed double bands sized 43 and 39 kDa in all lanes, including that of recombinant HDGF. This suggests the specificity and sensitivity of the antibody used in this analysis (Fig. 1
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Received for publication November 25, 2003.
Accepted for publication August 25, 2005.