Expression profiling in multistage hepatocarcinogenesis: identification of HSP70 as a molecular marker of early hepatocellular carcinoma

Arresting Cancer Proliferation by Small-Molecule Gene Regulation

A small library of pyrrole-imidazole polyamide-DNA alkylator (chlorambucil) conjugates was screened for effects on morphology and growth characteristics of a human colon carcinoma cell line, and a compound was identified that causes cells to arrest in the G2/M stage of the cell cycle. Microarray analysis indicates that the histone H4c gene is significantly downregulated by this polyamide. RT-PCR and Western blotting experiments confirm this result, and siRNA to H4c mRNA yields the same cellular response. Strikingly, reduction of H4 protein by >50% does not lead to widespread changes in global gene expression. Sequence-specific alkylation within the coding region of the H4c gene in cell culture was confirmed by LM-PCR. The compound is active in a wide range of cancer cell lines, and treated cells do not form tumors in nude mice. The compound is also active in vivo, blocking tumor growth in mice, without obvious animal toxicity.

Overexpression of cortactin is involved in motility and metastasis of hepatocellular carcinoma

BACKGROUND/AIMS

The molecular basis of the metastasis of hepatocellular carcinoma (HCC) is not fully understood. The aim of this study was to elucidate the crucial genes involved in metastasis of HCC.

METHODS

We compared expression profiles among highly metastatic HCC cell lines and non-metastatic HCC cell lines by using oligonucleotide array to identify genes associated with metastasis. We further investigated the effect of identified gene on cell motility and metastasis in vitro and in vivo. Finally, we examined immunohistochemistry in human tissue samples.

RESULTS

We identified 39 genes whose expression levels were significantly correlated with metastatic ability (P<0.05). Of these genes, we further investigated cortactin, because this cortical actin-associated protein is a substrate of Src, whose activation has been shown to be involved in HCC cell migration and metastasis. Overexpression of cortactin in a non-metastatic HCC cell line increased cell motility, and resulted in metastasis in an orthotopic model. Furthermore, immunohistochemical expression of cortactin revealed its significant overexpression in HCC with intrahepatic metastasis compared with HCC without intrahepatic metastasis (P<0.005).

CONCLUSIONS

Overexpression of cortactin may play a role in the metastasis of HCC by influencing cell motility, and cortactin could be a sensitive marker for HCC with intrahepatic metastasis.

Imaging of Early Hepatocellular Carcinoma and Adenomatous Hyperplasia (Dysplastic Nodules) with Dynamic CT and a Combination of CT and Angiography: Experience with Resected Liver Specimens

Early hepatocellular carcinoma (HCC) as defined by the Liver Cancer Study Group of Japan would correspond to high-grade dysplastic nodules with small foci of HCC in the majority of cases, using the classification system proposed by the International Working Party. A large number of early HCCs were revealed to be hypo- or isovascular in the arterial phase of dynamic CT. Only 5% of the lesions evaluated were hypervascular, which contrasted with advanced small HCCs, of which 94% were hypervascular. CT arterial portography (CTAP) showed hypoattenuation in 66% of early HCCs and isoattenuation in 34%. CT hepatic arteriography (CTHA) demonstrated hypoattenuation in 55% of early HCC, isoattenuation in 30% and hyperattenuation in 15%. These findings suggest that most early HCCs receive equal or reduced blood supply from both portal and arterial flow compared with surrounding noncancerous parenchyma. In contrast, 97% of small HCCs are hypoattenuated on CTAP, and 93% are hyperattenuated on CTHA. For nodule-in-nodule type HCC (advanced HCC within early HCC), the CT attenuation of the central and peripheral portions revealed areas of isolated advanced HCC and isolated early HCC, respectively. Adenomatous hyperplasia (low-grade dysplastic nodules) was not readily differentiated using the various imaging modalities, mainly due to the smaller size of these lesions compared to early HCC and/or a portal and arterial blood supply very similar to that of the surrounding parenchyma. Hemodynamic changes in cirrhotic liver were similarly evaluated using CTAP and CTHA, and the treatment of early HCC is briefly discussed herein.

Construction and selection of subtracted cDNA library of mouse hepatocarcinoma cell lines with different lymphatic metastasis potential

AIM: In order to elucidate the molecular mechanism of lymphatic metastasis of hepatocarcinoma, we detected the difference of gene expression between mouse hepatocarcinoma cell lines Hca-F and Hca-P with different lymphatic metastasis potential.

METHODS: cDNA of Hca-F cells was used as a tester and cDNA of Hca-P cells was used as a driver. cDNAs highly expressed in Hca-F cells were isolated by the suppression subtractive hybridization (SSH) method. The isolated cDNA was cloned into T/A cloning vector. The ligation products were transformed into DH5 α competent cells. Individual clones were randomly selected and used for PCR amplification. Vector DNA from positive clones was isolated for sequencing.

RESULTS: There were 800 positive clones in amplified subtracted cDNA library. Random analysis of 160 clones with PCR showed that 95% of the clones contained 100-700 bp inserts. Analysis of 20 sequenced cDNA clones randomly picked from the SSH library revealed 4 known genes (mouse heat shock protein 84 ku, DNA helicase, ribosomal protein S13 ,ethanol induced 6 gene) and 3 expressed sequence tags (ESTs). Four cDNAs showed no homology and presumably represent novel genes.

CONCLUSION: A subtracted cDNA library of differentially expressed genes in mouse heptocarcinoma cell lines with different lymphatic metastasis potential was successfully constructed with SSH and T/A cloning techniques. The library is efficient and lays a solid foundation for searching new lymphatic metastasis related genes. The expression of mouse heat shock protein gene, DNA helicase and other 4 novel gene may be different between mouse heptocarcinoma cell lines with different lymphatic metastasis potential.

Expression profiling in hepatocellular carcinoma with intrahepatic metastasis: identification of high-mobility group I(Y) protein as a molecular marker of hepatocellular carcinoma metastasis

Hepatocellular carcinoma (HCC) is one of the most common and aggressive human malignancies. Its high mortality rate is mainly a result of intra-hepatic metastases. To investigate the detailed genetic mechanisms in cancer metastasis, we compared the expression profiles of 20 HCCs with intrahepatic metastasis and 10 HCCs without intrahepatic metastasis using an oligonucleotide array. Of the approximately 12,600 genes that were analyzed, we identified 34 genes whose expression levels were significantly correlated with intrahepatic metastasis (P<0:05). Of these genes, we further investigated the expression of high-mobility group I(Y) [HMG-I(Y)] protein. Real-time quantitative reverse transcription polymerase chain reaction (RT-PCR) confirmed that HMG-I(Y) was upregulated in HCC with intrahepatic metastasis, compared to its level in HCC without intrahepatic metastasis. Further immunohistochemical examination of HMG-I(Y) revealed a significant overexpression in HCC with intrahepatic metastasis, compared with that in HCC without intrahepatic metastasis (P<0:05). These results indicate that the molecular signatures of HCC with intrahepatic metastasis and of HCC without intrahepatic metastasis are clearly different. HMG-I(Y) expression was associated with intrahepatic metastasis and may be a predictive marker of HCC intrahepatic metastasis.

Accessibility of nuclear chromatin by DNA binding polyamides

Pyrrole-imidazole polyamides bind DNA with affinities comparable to those of transcriptional regulatory proteins and inhibit the DNA binding activities of components of the transcription apparatus. If polyamides are to be useful for the regulation of gene expression in cell culture experiments, one pivotal issue is accessibility of specific sites in nuclear chromatin. We first determined the kinetics of uptake and subcellular distribution of polyamides in lymphoid and myeloid cells using fluorescent polyamide-bodipy conjugates and deconvolution microscopy. Then cells were incubated with a polyamide-chlorambucil conjugate, and the sites of specific DNA cleavage in the nuclear chromatin were assayed by ligation-mediated PCR. In addition, DNA microarray analysis revealed that two different polyamides generated distinct transcription profiles. Remarkably, the polyamides affected only a limited number of genes.

Significant correlation between expression level of HSP gp96 and progression of hepatitis B virus induced diseases

AIM: Gp96, also known as Grp94, is a member of heat shock protein (HSP) family and binds repertoires of peptides thereof eliciting peptide-specific T cell immune responses. It predominantly locates inside the endoplasmic reticulum (ER) with some cell surface expression in certain cancerous cells. Previous studies have shown that gp96 expression level was up-regulated in tumor cells, including hepatocellular carcinoma (HCC). However, relationship between the extent of gp96 expression and disease progression especially HBV-induced chronic infection, cirrhosis and hepatocellular carcinoma, has not been addressed before. As primary HCC can be induced and progressed from chronic hepatitis B virus (HBV) infection and HBV-induced cirrhosis, we designed an immunohistochemical experiment to test the correlation between gp96 expression level and HBV-induced disease progression, from chronic HBV infection, cirrhosis to HCC.

METHODS: We chose liver samples from different patients of hepatitis B virus induced diseases, including chronic hepatitis B (77 patients), cirrhosis (27 patients) and primary HCC (30 patients), to test the expression level of gp96 in different affected groups. Formalin-fixed, and paraffin-embedded liver tissues taken from these patients were immuno-stained by using an anti-gp96 monoclonal antibody for the expression level of gp96 protein in the sections. In addition, Western blotting of whole cell lysates derived from established human embryonic liver cell lines and several human HCC cell lines (Huh7, HepG2, SSMC-7721) was compared with the expression of gp96.

RESULTS: We found that the extent of elevated gp96 expression was significantly correlated with the disease progression, and was the highest in HCC patients, lowest in chronic HBV infection and was that of the cirrhosis in the middle.

CONCLUSION: Increased expression of gp96 might be used as a diagnostic or prognostic bio-marker for the HBV infection and HBV-induced diseases.

Expression of HSP 70 and caspase 3 and their significance in hepatocellular carcinoma tissues

AIM: To investigate the expression of heat shock protein 70 (HSP70) and caspase 3 protein and their clinical significance in hepatocellular carcinomas and surrounding liver tissues.

METHODS: The expression of HSP70 and caspase 3 protein were detected by immunohistochemistry in hepatocellular carcinomas (HCC) and their surrounding liver tissues.

RESULTS: The positive rate and intensity of HSP70 in HCCs were significantly higher than those in pericarcinomatous liver tissues (68.6% vs 31.4%, P < 0.01), and these of caspase protein were significantly lower (17.1% vs 35.7%, P < 0.01). The expression level of HSP70 and caspase protein in HCCs was remarkably related to differentiation degree and tumor size of HCCs, and the poorer differentiation, the stronger the expression of HSP70 (F = 5.219 and 5.421 respectively, P < 0.01), the weaker the expression of caspase 3 protein (F = 5.944 and 4.571 respectively, P < 0.01). The correlation analysis indicated that there was a negative relationship between expression of HSP70 and caspase protein in HCC and their surrounding liver tissues (r = 0.4 126 and 0.5 237 respectively, P < 0.01).

CONCLUSION: The expression of HSP70 may make uncontrolled growth and unceasingly increased malignant degree of HCC by accelerating cell transformation and proliferation and inhibiting apoptosis. HSP70 may be an important marker for evaluation of prognosis in patients with HCC.

Identification of Soluble NH2-Terminal Fragment of Glypican-3 as a Serological Marker for Early-Stage Hepatocellular Carcinoma

For detection of hepatocellular carcinoma (HCC) in patients with liver cirrhosis, serum alpha-fetoprotein has been widely used, but its sensitivity has not been satisfactory, especially in small, well-differentiated HCC, and complementary serum marker has been clinically required. Glypican-3 (GPC3), a heparan sulfate proteoglycan anchored to the plasma membrane, is a good candidate marker of HCC because it is an oncofetal protein overexpressed in HCC at both the mRNA and protein levels. In this study, we demonstrated that its NH(2)-terminal portion [soluble GPC3 (sGPC3)] is cleaved between Arg(358) and Ser(359) of GPC3 and that sGPC3 can be specifically detected in the sera of patients with HCC. Serum levels of sGPC3 were 4.84 +/- 8.91 ng/ml in HCC, significantly higher than the levels seen in liver cirrhosis (1.09 +/- 0.74 ng/ml; P < 0.01) and healthy controls (0.65 +/- 0.32 ng/ml; P < 0.001). In well- or moderately-differentiated HCC, sGPC3 was superior to alpha-fetoprotein in sensitivity, and a combination measurement of both markers improved overall sensitivity from 50% to 72%. These results indicate that sGPC3 is a novel serological marker essential for the early detection of HCC.

Altered gene expression in acute systemic inflammation detected by complete coverage of the human liver transcriptome

The goal of the current study was to provide complete coverage of the liver transcriptome with human probes corresponding to every gene expressed in embryonic, adult, and/or cancerous liver. We developed dedicated tools, namely, the Liverpool nylon array of complementary DNA (cDNA) probes for approximately 10,000 nonredundant genes and the LiverTools database. Inflammation-induced transcriptome changes were studied in liver tissue samples from patients with an acute systemic inflammation and from control subjects. One hundred and fifty-four messenger RNAs (mRNA) correlated statistically with the extent of inflammation. Of these, 134 mRNA samples were not associated previously with an acute-phase (AP) response. The hepatocyte origin and proinflammatory cytokine responsiveness of these mRNAs were confirmed by quantitative reverse-transcription polymerase chain reaction (Q-RT-PCR) in cytokine-challenged hepatoma cells. The corresponding gene promoters were enriched in potential binding sites for inflammation-driven transcription factors in the liver. Some of the corresponding proteins may provide novel blood markers of clinical relevance. The mRNAs whose level is most correlated with the AP extent (P <.05) were enriched in intracellular signaling molecules, transcription factors, glycosylation enzymes, and up-regulated plasma proteins. In conclusion, the hepatocyte responded to the AP extent by fine tuning some mRNA levels, controlling most, if not all, intracellular events from early signaling to the final secretion of proteins involved in innate immunity. Supplementary material for this article can be found on the HEPATOLOGY website (http://interscience.wiley.com/jpages/0270-9139/suppmat/index.html).

Apg-2 has a chaperone-like activity similar to Hsp110 and is overexpressed in hepatocellular carcinomas

Hepatocellular carcinoma (HCC) is the fifth most common cancer in the world. We constructed subtracted cDNA libraries enriched with genes overexpressed in HCCs. Among the 17 genes identified were molecular chaperones, Hsp110, Hsp90B, and Hsp70-1. Expression of the Hsp110 family members was further analyzed, and increased transcript levels of Hsp110 and Apg-2, but not Apg-1, were found in 12 and 14, respectively, of 18 HCCs. Immunohistochemical analysis demonstrated the overexpression of the proteins in tumor cells. Apg-2 had chaperone ability similar to Hsp110 in a thermal denaturation assay using luciferase, and showed anti-apoptotic activity. These results suggest that the Hsp110 family members play important roles in hepatocarcinogenesis through their chaperoning activities.

Heat shock response:hsp70 in environmental monitoring

Heat shock proteins (Hsps) are a ubiquitous feature of cells in which these proteins cope with stress-induced denaturation of other proteins. Among the different families of Hsps, the 70 kDa family (hsp70) is the most highly conserved and has been most extensively studied. Apart from their primary role in cellular defense under stress condition, a number of studies in recent years have shown the immense potential of hsp70 in pollution monitoring using even transgenic approach both in vivo and in vitro. This article reviews the recent developments in the widespread application of hsp70 in environmental risk assessment.

EBP50, a beta-catenin-associating protein, enhances Wnt signaling and is over-expressed in hepatocellular carcinoma

Wnt signaling mediated by beta-catenin plays crucial roles in the development of hepatocellular carcinoma and other cancers such as colorectal cancer. beta-Catenin associates with T-cell factor (TCF) transcription factors and functions as a transcriptional activator in the nucleus. By protein interaction screening, we identified EBP50, a cytoplasmic protein with 2 PDZ domains, as a beta-catenin-associating molecule. EBP50 interacted with beta-catenin through its carboxyl-PDZ domain in vitro and in vivo. Northern blot and RT-PCR analysis revealed an increase of EBP50 messenger RNA (mRNA) in hepatocellular carcinoma (HCC) cell lines and surgical specimens of human HCC. Over-expression of EBP50 protein with focal nuclear localization was detected in human HCC. In human HCC and colorectal cancer cell lines, EBP50 enhanced beta-catenin/TCF-dependent transcription in a dose-dependent manner. In an HCC cell line, over-expression of the carboxyl PDZ domain resulted in a decrease of endogenous beta-catenin/TCF transactivation. EBP50 promoted beta-catenin-mediated transactivation only in cells in which beta-catenin was already stabilized, suggesting that EBP50 may work with stabilized beta-catenin for transcriptional regulation. In conclusion, the EBP50/beta-catenin complex promotes Wnt signaling, and over-expression of EBP50 may work cooperatively with beta-catenin in the development of liver cancer.