Identification of a 1-cM region of common deletion on 4q35 associated with progression of hepatocellular carcinoma

The association of frequent allelic loss on 17p13.1 with early metastatic recurrence of hepatocellular carcinoma after liver transplantation

BACKGROUND AND OBJECTIVES

Identification and characterization of loss of heterozygosity (LOH) can determine putative tumor suppressor genes (TSGs) and provide a variety of molecular markers for hepatocellular carcinoma (HCC). This study aimed to investigate LOH status on chromosomes 4q, 6q, 8p, 9p, and 17p, and to explore their clinical significances in HCC post-liver transplantation.

METHODS

A total of 37 patients with HCC who underwent liver transplantation were enrolled. LOH was examined using 34 microsatellite markers located on 4q13-3q5, 6q27, 8p22-p23, 9p21-p22, and 17p12-p13.

RESULTS

The frequency of LOH at each microsatellite locus ranged from 23% to 75%, with a mean value of 53.1%. Frequencies of LOH on 4q, 6q, 8p, 9p, and 17p were 62% (23 of 37), 30% (11 of 37), 49% (18 of 37), 46% (16 of 35), and 68% (25 of 37), respectively. LOHs on certain chromosomal regions were significantly associated with age, AFP level, tumor size, tumor multiplicity, histological grade, and metastatic recurrence.

CONCLUSIONS

LOH on 17p13.1 correlated to metastatic HCC recurrence, while LOH on 4q and 8p was found to be associated with progression of HCC. Thus, potential novel biomarkers or TSGs for prognosis and treatment of HCC may harbor on these regions.

Cytogenetic and array comparative genomic hybridization analysis of a series of hepatoblastomas

Hepatoblastoma is the most common primary hepatic tumor in children, and only a limited number of detailed karyotypic analyses have been reported to date. In the present study, cytogenetic abnormalities were identified in nine cases of hepatoblastoma from a single institution. Among characteristic chromosomal changes detected were simple numerical aberrations, structural alterations of chromosomes 1, 2, and 8, and the recurrent unbalanced rearrangements der(4)t(1;4)(q25.2;q35.1) and der(6)t(1;6)(q21;q26). Array comparative genomic hybridization was applied in four of the cases. The combined cytogenetic, molecular cytogenetic, and histopathologic analyses are presented here, together with clinical data. The results substantially confirm previous findings of aberrations involving chromosomal loci on 1q, 2 or 2q, 4q, 6q, 8 or 8q, and 20 as significant in the development and clinical course of this disease.

Genomic profiles associated with early micrometastasis in lung cancer: relevance of 4q deletion

PURPOSE

Bone marrow is a common homing organ for early disseminated tumor cells (DTC) and their presence can predict the subsequent occurrence of overt metastasis and survival in lung cancer. It is still unclear whether the shedding of DTC from the primary tumor is a random process or a selective release driven by a specific genomic pattern.

EXPERIMENTAL DESIGN

DTCs were identified in bone marrow from lung cancer patients by an immunocytochemical cytokeratin assay. Genomic aberrations and expression profiles of the respective primary tumors were assessed by microarrays and fluorescence in situ hybridization analyses. The most significant results were validated on an independent set of primary lung tumors and brain metastases.

RESULTS

Combination of DNA copy number profiles (array comparative genomic hybridization) with gene expression profiles identified five chromosomal regions differentiating bone marrow-negative from bone marrow-positive patients (4q12-q32, 10p12-p11, 10q21-q22, 17q21, and 20q11-q13). Copy number changes of 4q12-q32 were the most prominent finding, containing the highest number of differentially expressed genes irrespective of chromosomal size (P=0.018). Fluorescence in situ hybridization analyses on further primary lung tumor samples confirmed the association between loss of 4q and bone marrow-positive status. In bone marrow-positive patients, 4q was frequently lost (37% versus 7%), whereas gains could be commonly found among bone marrow-negative patients (7% versus 17%). The same loss was also found to be common in brain metastases from both small and non-small cell lung cancer patients (39%).

CONCLUSIONS

Thus, our data indicate, for the first time, that early hematogenous dissemination of tumor cells might be driven by a specific pattern of genomic changes.

Decreased expression of ING2 gene and its clinicopathological significance in hepatocellular carcinoma

The inhibitor of growth (ING) family member 2 (ING2) is a newly discovered member of ING family that can regulate a wide range of cellular processes including cell growth arrest, apoptosis, and DNA repair. Researches have shown that ING2 can activate p53 and p53-mediated apoptotic pathway involved in the hepatocarcinogenesis. To investigate the role of ING2 in hepatocellular carcinoma (HCC) pathogenesis, we analyzed the correlations between the ING2 expression level and clinicopathologic factors and studied its prognostic role in primary HCC. Using reverse transcription-polymerase chain reaction (RT-PCR) and Western blot, ING2 transcription and post-transcription level was found to be downregulated in the majority of tumors compared with matched non-tumors liver tissues (p=0.004 and p=0.014, respectively). The immunohistochemistry data indicated significant reduction of ING2 expression level in 44 of 84 (52.4%) HCC cases. In addition, the expression level of ING2 correlated with tumor size, histopathologic classification, serum AFP (p<0.05). Kaplan-Meier curves demonstrated that patients with reduced ING2 expression were at significantly increased risk for shortened survival time (p=0.009). Using multivariate analysis, ING2 expression was found to be an independent prognostic factor. Our data suggest that ING2 is involved in the progression of HCC, therefore it is considered to be a candidate tumor suppressor gene and its significantly decreased expression in HCC may lead to an unfavorable prognosis.

Y chromosome loss and other genomic alterations in hepatocellular carcinoma cell lines analyzed by CGH and CGH array

Hepatocellular carcinoma (HCC) is one of the most frequently occurring malignant tumors worldwide. The incidence of HCC is much higher in males than in females. In order to clarify the molecular basis of the male predominance in HCC, we have characterized the detailed genomic alterations in 5 hepatitis B virus integrated Korean HCC cell lines using G-banding, comparative genomic hybridization (CGH), fluorescence in situ hybridization (FISH), PCR, and CGH array. The commonest alterations were observed in chromosome 7 and Y, as well as chromosomal regions 1q, 8q, 4q, and 16q. The most frequent aberration of genomic material was gain of 1q and loss of chromosome Y. Significant loss of DNA copy number of the cancer related genes that are located on chromosome Y was detected by CGH array. By investigating the karyotypes of the previously reported 21 male HCC cell lines, we found 18 HCC cell lines with Y chromosome loss, indicating that this loss is a significant feature of HCC cell lines. We propose that Y chromosome loss in HCC cell lines may be responsible for the preponderance of males in HCC and its significance may lead to further studies for better understanding of carcinogenesis in HCC.

Review of genetic and epigenetic alterations in hepatocarcinogenesis

Hepatocellular carcinoma (HCC) is associated with multiple risk factors and is believed to arise from pre-neoplastic lesions, usually in the background of cirrhosis. However, the genetic and epigenetic events of hepatocarcinogenesis are relatively poorly understood. HCC display gross genomic alterations, including chromosomal instability (CIN), CpG island methylation, DNA rearrangements associated with hepatitis B virus (HBV) DNA integration, DNA hypomethylation and, to a lesser degree, microsatellite instability. Various studies have reported CIN at chromosomal regions, 1p, 4q, 5q, 6q, 8p, 10q, 11p, 16p, 16q, 17p and 22q. Frequent promoter hypermethylation and subsequent loss of protein expression has also been demonstrated in HCC at tumor suppressor gene (TSG), p16, p14, p15, SOCS1, RIZ1, E-cadherin and 14-3-3 sigma. An interesting observation emerging from these studies is the presence of a methylator phenotype in hepatocarcinogenesis, although it does not seem advantageous to have high levels of microsatellite instability. Methylation also appears to be an early event, suggesting that this may precede cirrhosis. However, these genes have been studied in isolation and global studies of methylator phenotype are required to assess the significance of epigenetic silencing in hepatocarcinogenesis. Based on previous data there are obvious fundamental differences in the mechanisms of hepatic carcinogenesis, with at least two distinct mechanisms of malignant transformation in the liver, related to CIN and CpG island methylation. The reason for these differences and the relative importance of these mechanisms are not clear but likely relate to the etiopathogenesis of HCC. Defining these broad mechanisms is a necessary prelude to determine the timing of events in malignant transformation of the liver and to investigate the role of known risk factors for HCC.

Allelic loss of chromosome 4q21 approximately 23 associates with hepatitis B virus-related hepatocarcinogenesis and elevated alpha-fetoprotein

Allelic loss of chromosome 4q is one of the most frequent genetic aberrations found in human hepatocellular carcinoma (HCC) and suggests the presence of putative tumor suppressor genes within this region. To precisely define the region containing these tumor suppressor genes for further positional cloning, we tried a detailed deletion mapping strategy in 149 HCCs by using 49 microsatellite markers covering 4q12 approximately 25. A common region with allelic loss has been identified based on the interstitial deletions occurring within it; this region is found between D4S1534 and D4S1572 (a 17.5-cM genetic interval). When we included all cases with limited aberration regions for comparison, 2 smaller regions were derived: 1 between D4S1534 and D4S2460 (3.52 cM) and 1 between D4S2433 and D4S1572 (8.44 cM). A few candidate genes were found to be down-regulated in HCCs, but without sequence mutations. In these HCCs, 4q alleleic loss was associated with hepatitis B virus infection status and the elevation of serum alpha-fetoprotein (>/=400 ng/mL). In conclusion, the current study not only mapped a common allelic loss region on chromosome 4q, but it also revealed that its loss may be involved in hepatitis B virus-related hepatocarcinogenesis and the elevation of serum alpha-fetoprotein.

Loss of heterozygosity on chromosome 4q32-35 in sporadic basal cell carcinomas: evidence for the involvement of p33ING2/ING1L and SAP30 genes

BACKGROUND

Studies on basal cell carcinoma (BCC) have demonstrated that patched gene and p53 gene located at 9q22.3 and 17p13 are the main genes responsible for the onset of this tumor. In order to identify a possible involvement of other tumor suppressor genes, we screened 19 cases of BCCs for loss of heterozygosity (LOH).

METHODS

The analysis was performed on tumoral tissue and on corresponding normal tissue by using a panel of 37 polymorphic markers spanning 26 chromosomal regions.

RESULTS

We observed that only four chromosomal regions, 4q32 (30.00%), 4q35 (27.27%), 9q21-22 (28.57%), and 9q22-qter (35.71%), demonstrated a significative LOH (>20%), even if others show a borderline percentage (15-20%) of imbalance (1q32, 3p24, 10p22.1, and 17q21.3).

CONCLUSIONS

Our findings suggest that a new chromosomal region mapping in the long arm of chromosome 4 could be involved in sporadic BCC carcinogenesis. Further analyses indicate that the minimal deleted region in 4q32-35 includes p33ING2/ING1L and SAP30, whose deletion could impair the G1-phase checkpoint control and favor gene silencing, respectively.

Allelotypic Characteristics of Thorotrast-Induced Intrahepatic Cholangiocarcinoma: Comparison to Liver Cancers not Associated with Thorotrast

To elucidate the genetic alterations that are specific to Thorotrast-induced liver cancers and their possible roles in tumorigenesis, we analyzed loss of heterozygosity (LOH) at 37 loci. Our previous study of liver cancers that were not associated with Thorotrast found LOH at 9 of these loci to be characteristic of intrahepatic cholangiocarcinoma (ICC), at 19 to be characteristic of hepatocellular carcinoma (HCC), and at 9 to be common to both ICC and HCC. LOH analysis was also performed in tissues of cholangiolocellular carcinoma, which is thought to originate from a common stem cell progenitor of hepatocytes and bile duct epithelial cells. We found frequent LOH at D4S1538, D16S2624 and D17S1303 to be common to all the subtypes of liver cancers, independent of the specific carcinogenic agent. In contrast, LOH at D4S1652 generally was not observed in Thorotrast-induced ICC. LOH analysis revealed that Thorotrast-induced ICC shares some LOH features with both ICC and HCC that were not induced by Thorotrast; however, it is more similar to ICC than to HCC in terms of genetic changes. This study could narrow down the crucial chromosomal loci whose deletions are relevant to hepatobiliary carcinogenesis irrespective of the carcinogenic agent. The study of LOH at loci other the those crucial ones may help us understand how the phenotype of liver cancers is determined.

Genetic evaluation of the dysplasia-carcinoma sequence in chronic viral liver disease: a detailed analysis of two cases and a review of the literature

Hepatocellular carcinoma (HCC) is one of the most frequent human malignancies, especially in Asia and Africa, but also in the Western world its incidence is increasing. HCC is a complication of chronic liver disease with cirrhosis as the most important risk factor. Viral co-pathogenesis due to hepatitis B virus (HBV) and hepatitis C virus (HCV) infection seems to be an important factor in the development of HCC. Curative therapy is often not possible due to the late detection of HCC. Thus, it is attractive to find parameters which predict malignant transformation in HBV- and HCV-infected livers. In the past decade, preneoplastic lesions, i.e. dysplastic foci or nodules, have gained interest as possible markers for imminent malignancy. Noteworthy, dysplastic liver lesions are increasingly detected by imaging techniques. We describe here two cases of chronic viral liver disease, one HBV-and one HCV-related, in which dysplastic lesions were present adjacent to HCC. In the HBV case, a (smaller) satellite of HCC was present as well. The neoplastic specimens were investigated by comparative genomic hybridization (CGH) and in situ hybridization (ISH). Both methods revealed multiple genetic alterations in the HCCs. The genetic patterns of the HBV-related HCC and the satellite tumor showed many shared alterations suggesting a clonal relationship. A subset of genetic changes were already present in dysplasias illustrating their preneoplastic nature. Surrounding liver cirrhosis samples did not display chromosomal aberrations. A literature survey illustrates the relative paucity of information concerning genetic alterations in preneoplastic liver lesions. However, all the data strongly suggests a role for liver cell dysplasia as a precursor condition of liver cell cancer.

A comprehensive karyotypic analysis on Korean hepatocellular carcinoma cell lines by cross-species color banding and comparative genomic hybridization

Chromosomal aberrations were investigated in hepatitis B virus integrated into the hepatocellular carcinoma (HCC) cell lines SNU-368, SNU-449, SNU-398, SNU-182, and SNU-475 using Giemsa-banding, cross species color banding, and comparative genomic hybridization (CGH). The origins of the marker chromosomes were confirmed by fluorescence in situ hybridization with constructed chromosome painting probes. Each cell line had unique modal karyotypic characteristics and showed variable numbers of numerical and structural clonal cytogenetic aberrations. The gains were commonly detected on chromosome 1, and chromosome regions 6p, 7q, 8q, 10p, 17q, and 20; the losses were often found on 4q21 approximately qter, 13, 18q21 approximately qter, and Y. In particular, the breakpoints on 1p36, 1p13 approximately q21, 2p13 approximately q11, 6q10 approximately q11, 7q11, 7q22, 14q10, 16q10 approximately q13, 17q21, 18q21, and 19p11 approximately q11 were involved frequently at the multiple rearranged lesions. CGH analysis further confirmed the cytogenetic data, and the nonrandom rearrangements data suggested the candidate regions for the genes to be isolated which were related to HCC.

Combined hypermethylation and chromosome loss associated with inactivation of SSI-1/SOCS-1/JAB gene in human hepatocellular carcinomas

We previously demonstrated using restriction landmark genomic scanning-based 2-dimensional genome electrophoresis method decreased results of 16 primary hepatocellular carcinomas (HCCs) revealed reduction of intensity of 60 NotI-landmark spots, and increase in five spots that were frequently observed in HCCs. Most frequently decreased spot (14/16 HCCs) was identified to it corresponds to a gene encoding SSI-1, a JAK-binding protein (SSI-1/SOCS-1/JAB) that regulated the JAK/STAT signal transduction pathway. This signaling pathway is important for relaying signals from various cytokines outside the cell to the inside. Expression level of SOCS-1 messenger RNA was markedly suppressed in 50% of HCCs (4/8). Loss of heterozygosity at the SSI-1 gene, was found in all cases with aberrant expression. Methylation analysis of the CpG-rich regions of SSI-1 gene revealed hypermethylation of these regions. In an additional series of methylation analysis using 30 HCCs, 16 (53%) showed hypermethylation of the gene. These results indicate that the SSI-1 gene is silenced in a substantial portion of HCC though the combined mechanisms of methylation of either 5' or exon CpG rich regions and by a chromosomal loss of the remaining allele.

Down-regulation of a novel gene, DRLM, in human liver malignancy from 4q22 that encodes a NAP-like protein

Frequent observations of allelic loss in chromosomal band 4q21-22 in hepatocellular carcinoma (HCC) have suggested the presence of one or more tumor suppressor genes in this region. We screened HCC cell lines by reverse transcription-polymerase chain reaction (RT-PCR) to detect alterations in expression of genes within the region in question by examining expressed sequence tags located there. These experiments identified a full-length cDNA of 2311 bp in length encoding a novel, 182-amino-acid peptide belonging to the class of nucleosome assemble protein lacking nuclear localization signal sequence. Polyclonal antibody was raised by expression of a constructed recombinant glutathione S-transferase fusion protein. in vitro expression and Western blotting revealed that the novel protein distributed in cytoplasm. This gene showed loss or extreme decrease of expression in five of 13 HCC cell lines. We named it DRLM ('down-regulated in liver malignancy'). Our results suggest that loss of expression of DRLM at 4q21-22 may play an important role in human hepatocarcinogenesis.

Down-regulation of annexin A10 in hepatocellular carcinoma is associated with vascular invasion, early recurrence, and poor prognosis in synergy with p53 mutation

Annexins (ANXs) are a large group of calcium-binding proteins participating in diverse important biological processes. ANXA10 is the least expressed new member of unknown function. We showed that ANXA10 mRNA was expressed in adult liver and hepatocellular carcinoma (HCC), but not in multiple adult and fetal tissues, cholangiocarcinoma, and several other common carcinomas. Of 182 unifocal primary HCCs, ANXA10 mRNA was dramatically reduced in 121 (66%), and the down-regulation correlated with p53 mutation (P = 0.024), early intrahepatic tumor recurrence (P = 0.0007), and lower 4-year survival (P = 0.0014). Down-regulation of ANXA10 was twofold more frequent in large than small HCCs (P = 0.0012), in grade II to III than grade I HCC (P < 0.00001), and in stage IIIA to IV than stage I to II HCC (P < 0.00001). Moreover, ANXA10 down-regulation and p53 mutation acted synergistically toward high-grade (P < 0.00001), high-stage HCC (P < 0.00001), and poorer prognosis (P = 0.0025). Our results indicate that the expression of the tissue- and tumor-restricted ANXA10 is a marker of liver cell differentiation and growth arrest, and its down-regulation associated with malignant phenotype of hepatocytes, vascular invasion, and progression of HCC, leading to poor prognosis. Thus, ANXA10 might serve as a new potential target of gene therapy for HCC.

Genetic mechanisms of hepatocarcinogenesis

The development of hepatocellular carcinoma (HCC) is a multistep process associated with changes in host gene expression, some of which correlate with the appearance and progression of tumor. Preneoplastic changes in gene expression result from altered DNA methylation, the actions of hepatitis B and C viruses, and point mutations or loss of heterozygosity (LOH) in selected cellular genes. Tumor progression is characterized by LOH involving tumor suppressor genes on many chromosomes and by gene amplification of selected oncogenes. The changes observed in different HCC nodules are often distinct, suggesting heterogeneity on the molecular level. These observations suggest that there are multiple, perhaps redundant negative growth regulatory pathways that protect cells against transformation. An understanding of the molecular pathogenesis of HCC may provide new markers for tumor staging, for assessment of the relative risk of tumor formation, and open new opportunities for therapeutic intervention.

Specific association between alcohol intake, high grade of differentiation and 4q34-q35 deletions in hepatocellular carcinomas identified by high resolution allelotyping

One of the most frequent deletions in hepatocellular carcinoma (HCC) is that involving the long arm of chromosome 4 (30 to 70% of the cases). These chromosomal deletions are closely related to hepatitis B virus (HBV) infection. A tumor suppressor gene (TSG) located on 4q has been proposed in liver carcinogenesis, but has not been identified as yet. Despite previous LOH studies focused on 4q in HCC, a clear minimal common region of deletion (MCRD) could not be delimited. To further investigate the role of chromosome 4q LOH in the pathogenesis of HCC, 85 microsatellite markers spanning chromosome 4q were systematically analysed in a series of 154 well-characterized primary liver tumors. In 59 tumors (38%), LOHs were observed for at least two adjacent markers. Analysis of 31 tumors demonstrating a partial or interstitial 4q deletion allowed to define three MCRDs of 15, 9 and 8 Mb at the 4q22, 4q34 and 4q35 regions, respectively. Seven putative candidate genes located in 4q22, DAPP1, BMPR1B, PKD2, HERC3, SMARCAD1, CEB1 and ENH were screened for mutations but no somatic alterations were identified. Search for relationships between the specific regions of deletion and clinical parameters showed a significant association between loss of the 4q34-35 region with alcohol intake (P=0.005) and with high grade of differentiation (P=0.02). These results are in contrast with the close association between HBV infection and the whole 4q LOH and reveal heterogeneity of 4q LOH in relation to different risk factors. In the light of these new findings, which link different 4q LOH regions to different etiologic factors, the molecular mechanisms underlying 4q deletions in HCC and the targeted gene(s) remain to be identified.

Analysis of chromosomal aberrations in large hepatocellular carcinomas by comparative genomic hybridization

Hepatocellular carcinoma (HCC) is a very common and highly malignant tumor, associated mainly with chronic viral hepatitis, cirrhosis of any cause, aflatoxin exposure and ethanol consumption. The aim of this study was to map genomic aberrations in HCC by a recently developed technique: comparative genomic hybridization (CGH). We applied CGH on 17 liver specimens, of which seven were HCCs. The rest were benign liver tumors, cirrhotic and normal livers, and other liver malignancies. Our study included mainly large tumors (mean size 10.5 cm) unrelated to viral hepatitis or cirrhosis. Our CGH analysis detected genomic imbalances in 42% of HCCs. The common aberrations included DNA gains of 1q, 9p, and 8q and DNA losses of 17p, 13q, 9q, 4q, and 11q. Also, we detected trisomies 8, 9, 18 and 21, which have not been reported previously. Gains and losses of DNA found in this study probably involve oncogenes and tumor suppressor genes that play a role in the puzzle of hepatocarcinogenesis. This study also suggests a possible link between the size of the tumor and the burden of genetic changes.

An 8-cM interstitial deletion on 4q21-q22 in DNA from an infant with hepatoblastoma overlaps with a commonly deleted region in adult liver cancers

We performed molecular analysis of a germline interstitial deletion of chromosome 4 [del(4)(q21.22q23)], which had been observed in a male infant manifesting early-onset hepatoblastoma (HBL). The chromosomal anomaly in this child was associated with a unique congenital syndrome including HBL, atrial septal defect, ventricular septal defect, patent ductus arteriosus, mental retardation, and seizures. However, the patient did not exhibit a megalencephaly typical of 4q21-22 deletions. His HBL was associated with an increasing serum alpha-fetoprotein level and rapid growth. To define the chromosomal deletion at the molecular level in this child, we analyzed his lymphoblasts with fluorescence in situ hybridization, using as probes a panel of BAC/PAC genomic clones containing STS markers covering the 4q12-27 region. The analysis revealed that the affected chromosome had an 8-cM deletion within 4q21-q22, flanked by markers D4S2964 and D4S2966. This microdeletion overlaps with the commonly deleted region at 4q21-q22 that was recently defined in adult hepatocellular carcinomas.

DNA damage-inducible gene p33ING2 negatively regulates cell proliferation through acetylation of p53

The p33ING1 protein is a regulator of cell cycle, senescence, and apoptosis. Three alternatively spliced transcripts of p33ING1 encode p47ING1a, p33ING1b, and p24ING1c. We cloned an additional ING family member, p33ING2/ING1L. Unlike p33ING1b, p33ING2 is induced by the DNA-damaging agents etoposide and neocarzinostatin. p33ING1b and p33ING2 negatively regulate cell growth and survival in a p53-dependent manner through induction of G(1)-phase cell-cycle arrest and apoptosis. p33ING2 strongly enhances the transcriptional-transactivation activity of p53. Furthermore, p33ING2 expression increases the acetylation of p53 at Lys-382. Taken together, p33ING2 is a DNA damage-inducible gene that negatively regulates cell proliferation through activation of p53 by enhancing its acetylation.

Genome-wide analyses on loss of heterozygosity in hepatocellular carcinoma in Southern China

BACKGROUND/AIMS

To conduct a genome-wide analysis of loss of heterozygosity (LOH) and its clinical significance in hepatocellular carcinoma (HCC) in Southern China where high incidence of HCC was documented.

METHODS

LOH of 382 microsatellite loci on all autosomes were detected with polymerase chain reaction-based microsatellite polymorphism analyses in 104 HCC tumor tissues.

RESULTS

High frequency of LOH (>55.7%) was observed on chromosome 1p, 1q, 2q, 3p, 4q, 6q, 8p, 9p, 13q, 16q, and 17p. LOH rates on loci D4S2964 (4q21.21), D8S277 (8p23.1-pter) and D17S938 (17p13.1-p13.3) were significantly higher in cases with positive HBsAg than in those with negative HBsAg. Similarly, LOH on loci D1S214 (lp36.3), D1S2797 (1p34) and D3S3681 (3p11.2-p14.2) were more frequently detected in tumors with intrahepatic metastasis than in those without.

CONCLUSIONS

Status of LOH in HCC in Southern China is similar to that reported previously in other countries and areas. However, we firstly identified high-frequency LOH on chromosome 3p in HCC. Furthermore, HBV infection, as well as tumor intrahepatic metastasis, may be correlated with allelic losses on certain chromosome regions.

Human hepatocellular carcinoma is characterized by a highly consistent pattern of genomic imbalances, including frequent loss of 16q23.1-24.1

Comparative genomic hybridization (CGH) analysis was used to identify chromosomal imbalances in 52 human primary hepatocellular carcinomas (HCCs). The most prominent changes were gains of part or all of chromosome arms 8q (83% of cases) and 1q (73%) and loss of 16q (63%). Other commonly overrepresented sites were 5p, 7q, and Xq. Recurrent sites of DNA sequence amplification included 8q23--24 (five cases) and 11q13--14 (four cases). Other frequently underrepresented sites were 4q, 8p, 16p, and 17p. Taken collectively, these findings and data from other CGH studies of HCCs define a subset of chromosome segments that are consistently over- or underrepresented and highlight sites of putative oncogenes and tumor suppressor genes, respectively, involved in hepatocellular oncogenesis. Loss of heterozygosity analysis with a panel of polymorphic microsatellite markers distributed along 16q defined a minimal region of chromosomal loss at 16q23.1--24.1, suggesting that this region harbors a tumor suppressor gene whose loss/inactivation may contribute to the pathogenesis of many HCCs.

Inactivation of SSI-1, a JAK/STAT inhibitor, in human hepatocellular carcinomas, as revealed by two-dimensional electrophoresis

BACKGROUND/AIMS

Hepatocellular carcinoma (HCC) is one of the most common human cancers, and many efforts have been paid to discover aberrant expression control in HCC, however the specific molecular mechanisms involved in hepatocarcinogenesis remain to be determined.

METHODS

To investigate genomic changes that occur in human primary hepatocellular carcinomas (HCC), we carried out restriction landmark genomic scanning. This two-dimensional electrophoretic system displays 2000-3000 NotI-landmark sites in a single gel.

RESULTS

We detected one landmark spot that showed diminished signal intensities in a majority of the HCCs we examined. Cloning revealed that this spot represented a NotI-cluster sequence that was enriched with CpG dinucleotides in the promoter region of a gene encoding Janus kinase (JAK)-binding protein, SSI-1 (also known as JAB1 or SOCS-1). Expression of the SSI-1 gene was markedly reduced in half of eight HCCs analyzed.

CONCLUSIONS

This protein regulates the Janus kinase signal transducers and activators of transcription signal transduction pathway, which transmits signals from cytokines to the intracellular apparatus. These data suggest that dysregulation of the pathway relate with progression of HCC.

Characterization of genomic alterations in hepatoblastomas. A role for gains on chromosomes 8q and 20 as predictors of poor outcome

As data on the genomic alterations in hepatoblastoma (HB) are limited, 34 HB tumors and three HB cell lines were screened for DNA copy number changes by comparative genomic hybridization. The average number of chromosomal imbalances per tumor was 2.3 +/- 0.5 (mean +/- SEM) with gains sevenfold more frequent than losses. The most frequent gains of chromosomal material in HB tumors were on 2q (44%), 1q (41%), 2p (29%), 20 (24%), 22q (18%), 8q (15%), 8p and 12q (9% each), as well as 7q, 12p, and 17 (6% each) and the only recurrent loss was on 4q in 12% of cases. Highly amplified sequences were identified in four tumors and mapped to 2q24 in two cases, to 8q in two cases (once to 8q11.2-q13 and once to 8q11.2-q21.3) as well as to 10q24-q26 in one case. In one cell line, highly amplified DNA sequences were mapped to 7p and 8q. Comparison to previously published data on this series of HB revealed that the number of chromosomal imbalances was significantly higher in HB tumors with loss of heterozygosity on 11p (P = 0.03), whereas in five of 10 HB biopsies without chromosomal imbalances, beta-catenin gene mutations were found. HB patients were divided into a good (no evidence of disease) and a poor (died of disease) outcome group according to their clinical course after standard therapy. Two alterations were found to be significantly associated with poor outcome: gain on 8q (P = 0.007) and gain on 20 (P = 0.009). In summary, our analysis allowed the identification of gains on chromosomes 1q and 2 as hallmark DNA copy number changes in HB with 2q24 as a critical chromosomal band. Furthermore, this study provided evidence that gains on 8q and 20 play a role as markers of prognostic significance in HB.