Molecular cytogenetic evaluation of virus‐associated and non‐viral hepatocellular carcinoma: analysis of 26 carcinomas and 12 concurrent dysplasias

Abstract

The worldwide incidence of hepatocellular carcinoma (HCC) is approximately one million cases a year. This makes HCC one of the most frequent human malignancies, especially in Asia and Africa, although the incidence is increasing also in the western world. HCC is a complication of chronic liver disease, with cirrhosis as the most important risk factor. Viral co-pathogenesis makes cirrhosis due to hepatitis B (HBV) and hepatitis C virus (HCV) infection a very important factor in the development of HCC. As curative therapy is often ruled out due to the late detection of HCC, it would be attractive to find parameters which predict malignant transformation in HBV- and HCV-infected livers. This study has used comparative genomic hybridization (CGH) to analyse 26 HCCs (11 non-viral, nine HBV, six HCV) and 12 concurrent dysplasias (five non-viral, five HBV, two HCV). Frequent gain (> or =25% of all tumours) was detected, in decreasing order of frequency, on 8q (69%), 1q (46%), 17q (46%), 12q (42%), 20q (31%), 5p (27%), 6q (27%), and Xq (27%). Frequent loss (> or =25% of all tumours) was found, in decreasing order of frequency, on 8p (58%), 16q (54%), 4q (42%), 13q (39%), 1p (35%), 4p (35%), 16p (35%), 18q (35%), 14q (31%), 17p (31%), 9p (27%), and 9q (27%). Minimal overlapping regions could be determined at multiple locations (candidate genes in parentheses). Minimal regions of overlap for deletions were assigned to 4p14-15 (PCDH7), 8p21-22 (FEZ1), 9p12-13, 13q14-31 (RB1), 14q31 (TSHR), 16p12-13.1 (GSPT1), 16q21-23 (CDH1), 17p12-13 (TP53), and 18q21-22 (DPC4, DCC). Minimal overlapping amplified sites could be seen at 8q24 (MYC), 12q15-21 (MDM2), 17q22-25 (SSTR2, GH1), and 20q12-13.2 (MYBL2, PTPN1). A single high level amplification was seen on 5q21 in an HBV-related tumour. Aberrations appeared more frequent in HBV-related HCCs than in HCV-associated tumours (p=0.008). This was most prominent with respect to losses (p=0.004), specifically loss on 4p (p=0.007), 16q (p=0.04), 17p (p=0.04), and 18q (p=0.03). In addition, loss on 17p was significantly lower in non-viral cancers than in HBV-related HCC (p<0.001). Furthermore, loss on 13q was more prevalent in HCCs in non-cirrhotic livers (p=0.02), thus suggesting a different, potentially more aggressive, pathway in neoplastic progression. A tendency (p=0.07) was observed for loss on 9q in high-stage tumours; no specific changes were found in relation to tumour grade. A subset of the HCC-associated genetic changes was disclosed in the preneoplastic stage, i.e. liver cell dysplasia. This group of dysplasias showed frequent gain on 17q (25%) and frequent loss on 16q (33%), 4q (25%), and 17p (25%). The majority of the dysplasias with alterations revealed genetic changes that were also present in the primary tumour. In conclusion, firstly, this study has provided a detailed map of genomic changes occurring in HCC of viral and non-viral origin, and has suggested candidate genes. Loss on 17p, including the TP53 region, appeared significantly more prevalent in HBV-associated liver ca...

Molecular cloning and characterization of a novel gene which is highly expressed in hepatocellular carcinoma

“…The multiple hepatocarcinogenesis involves large molecular events including genetic and epigenetic changes, which accumulate through progression (Hui and Makuuchi, 1999;Zimmermann et al, 1997). The genetic deviation encompasses DNA rearrangements associated with viral genome integration (Zondervan et al, 2000), point mutations (Ogata et al, 1991;Shimizu et al, 1999;de La Coste et al, 1998), loss of heterozygosity (Teeguarden et al, 2000;Kondo et al, 2000), chromosomal amplifications (Kawate et al, 1999), changes in methylation (Kondo et al, 2000;Shen et al, 1998), translocations (Keck et al, 1999), and gain or loss of imprinting (de Souza et al, 1997;Schwienbacher et al, 2000). These changes could occur in a variety of cellular genes leading to escape from normal cellular and environmental controls.…”

Positional expression profiling indicates candidate genes in deletion hotspots of hepatocellular carcinoma

“…For example, deleted in liver cancer 1 (DLC1) on 8p21-p22, 7 E-cadherin (CDH1) on 16q12.1-q23.1 8 and tumor protein p53 (TP53) on 17p13. 9 Candidate genes in the smallest overlapping regions 4q12-q23 10 and 4q31-q35, on the other hands, remains undescribed. 11,12 As regions of aberrant genomic loci can harbor more than one tumor-related genes, such as RASSF1A, MLH1, TGFBR2 and BLU on chromosome 3p21, [13][14][15][16] the existence of more than one tumor-suppressor gene within common deleted sites of hepatocellular carcinoma cannot be ruled out.…”

Genetic and expression analysis of the KCNRG gene in hepatocellular carcinomas

“…The site of the cellular DNA at which the HBV integrates frequently undergoes rearrangement, resulting in a translocation, and deletion (Ogata et al,1990;Hino et al, 1996;Nakamura et al, 1998;Okabe et al, 2000). Furthermore, an allelic loss at 13q is significantly associated with an advanced tumor stage and a poor prognosis (Zondervan et al, 2000;Kusano et al, 2002;Wong et al, 2002). Therefore, it is possible that an allelic loss of KCNRG could be an additional mechanism for the progression of HCC.…”

“…Several cytogenetic studies reported that chromosome 13q is one of the common deletion regions and contains one or more of the genes associated with the development or progression of HCC (Niketeghad et al, 2001;Crawley et al, 2002; Genetic and expression analysis of the KCNRG gene in hepatocellular carcinomas Kusano et al, 2002;Wong et al, 2002). Surprisingly, allelic losses at 13q were found to be associated with an advanced tumor stage and a poor prognosis (Zondervan et al, 2000;Kusano et al, 2002;Wong et al, 2002). The potassium channels are ubiquitous multisubunit membrane proteins that regulate the membrane potential in several cell types, and potassium-dependent alterations in the membrane potential play a pivotal role in the proliferation of many types of normal and tumor cell lines.…”