Functional mapping of tissue-specific elements of the human alpha-fetoprotein gene enhancer

Super-resolution Multispectral Imaging Nanoimmunosensor for Simultaneous Detection of Diverse Early Cancer Biomarkers

In medical diagnosis, relying on only one type of biomarker is insufficient to accurately identify cancer. Blood-based multicancer early detection can help identify more than one type of cancer from a single blood sample. In this study, a super-resolution multispectral imaging nanoimmunosensor (srMINI) based on three quantum dots (QDs) of different color conjugated with streptavidin was developed for the simultaneous screening of various cancer biomarkers in blood at the single-molecule level. In the experiment, the srMINI chip was used to simultaneously detect three key cancer biomarkers: carcinoembryonic antigen (CEA), C-reactive protein (CRP), and alpha-fetoprotein (AFP). The srMINI chip exhibited 108 times higher detection sensitivity of 0.18-0.5 ag/mL (1.1-2.6 zM) for these cancer biomarkers than commercial enzyme-linked immunosorbent assay kits because of the absence of interfering signals from the substrate, establishing considerable potential for multiplex detection of cancer biomarkers in blood. Therefore, the simultaneous detection of various cancer biomarkers using the developed srMINI chip with high diagnostic precision and accuracy is expected to play a decisive role in early diagnosis or community screening as a single-molecule biosensor.

HNF4A Haploinsufficiency in MODY1 Abrogates Liver and Pancreas Differentiation from Patient-Derived Induced Pluripotent Stem Cells

Maturity-onset diabetes of the young 1 (MODY1) is a monogenic diabetes condition caused by heterozygous HNF4A mutations. We investigate how HNF4A haploinsufficiency from a MODY1/HNF4A mutation influences the development of foregut-derived liver and pancreatic cells through differentiation of human induced pluripotent stem cells from a MODY1 family down the foregut lineage. In MODY1-derived hepatopancreatic progenitors, which expressed reduced HNF4A levels and mislocalized HNF4A, foregut genes were downregulated, whereas hindgut-specifying HOX genes were upregulated. MODY1-derived hepatocyte-like cells were found to exhibit altered morphology. Hepatic and β cell gene signatures were also perturbed in MODY1-derived hepatocyte-like and β-like cells, respectively. As mutant HNF4A (p.Ile271fs) did not undergo complete nonsense-mediated decay or exert dominant negativity, HNF4A-mediated loss of function is likely due to impaired transcriptional activation of target genes. Our results suggest that in MODY1, liver and pancreas development is perturbed early on, contributing to altered hepatic proteins and β cell defects in patients.

•

HNF4A is downregulated and predominantly mislocalized in the cytoplasm in MODY1

•

Foregut markers, pancreatic and hepatic genes, were downregulated in MODY1-HPPs

•

A reciprocal upregulation of hindgut HOX genes was observed in MODY1-HPPs

•

Mutant HNF4A resulted in loss of transcriptional activation of target genes

Synchronous Presentation of Hepatoid Alpha-Fetoprotein-Producing Lung Cancer and Colorectal Adenocarcinoma

We describe the synchronous presentation of hepatoid adenocarcinoma of the lung and colorectal adenocarcinoma in a patient with elevated alpha-fetoprotein (AFP) serum levels. Our patient was treated after surgery with a conventional chemotherapy regimen including bevacizumab, an anti-vascular endothelial growth factor monoclonal antibody, which was demonstrated to improve the clinical results in the treatment of colorectal and lung cancer compared with chemotherapy alone, and is today approved both for colon and lung cancer.

Besides the unconventional association of the two cancer types in our patient and the unsatisfactory clinical benefit obtained with the medical treatment administered, we report on the significance of AFP serum levels as a tumor marker in this peculiar situation. In our patient these levels, monitored from the first clinical symptoms through the last chemotherapy course, did not show any correlation with the response to treatment or with the patient's overall outcome. In particular, the serum marker remained essentially unchanged after the surgical removal of the lung mass and the subsequent chemotherapy.

p55PIK regulates alpha-fetoprotein expression through the NF-κB signaling pathway

AIMS

Alpha-fetoprotein (AFP) is regarded as a diagnostic and prognostic biomarker and a potential therapeutic target for hepatocellular carcinoma (HCC). However, the regulation of AFP expression in HCC remains poorly understood. This study aimed to investigate the mechanism by which AFP expression is regulated by p55PIK, an isoform of PI3K.

MAIN METHODS

Human HCC cell lines (HepG2 and Huh-7) were treated with p55PIK specific competitive inhibitor or shRNA, or p55PIK overexpression vector, in the absence or presence of NF-κB inhibitor PDTC. AFP expression was detected by quantitative real-time PCR and Western blotting. NF-κB responsive elements in AFP enhancer region were characterized by luciferase reporter assay.

KEY FINDINGS

p55PIK significantly stimulated the expression of AFP by activating NF-κB signaling pathway in HCC cells. Furthermore, two NF-κB binding sites in AFP enhancer region were identified to be primarily responsible for p55PIK mediated upregulation of AFP expression.

SIGNIFICANCE

p55PIK/NF-κB signaling plays an important role in the upregulation of AFP expression in HCC.

Persistent α-Fetoprotein Elevation in Healthy Adults and Mutational Analysis of α-Fetoprotein Promoter, Enhancer, and Silencer Regions

Background/Aims

α-Fetoprotein (AFP) is normally <10 ng/mL in adults without malignancy or liver regeneration. However, hereditary or nonhereditary persistence of AFP in healthy adults may be encountered in clinical practice. This study describes four cases of persistent AFP elevation in healthy adults and investigates mutations in key transcription regulatory regions of the AFP gene as potential drivers of AFP overexpression.

Methods

Four healthy adults with persistently elevated AFP levels (12.1 to 186.1 ng/mL) for >1 year, and 20 controls with low AFP levels (<0.61 to 2.9 ng/mL) were included in the study. AFP levels were collected from the families of two of the patients. We sequenced five regions that are critical for AFP expression: a promoter, two enhancers, and two silencers.

Results

One of the two cases in which family information was represented is the first case of hereditary persistence of AFP in South Korea. Mutations related to AFP overexpression were not found in the transcription regulatory regions among the four patients.

Conclusions

Persistent AFP elevation is a heterogeneous condition with or without a hereditary pattern and may be caused by factors outside of transcription regulatory region changes. Further research on the mechanism of AFP elevation is needed.

Cell-specific expression of artificial microRNAs targeting essential genes exhibit potent antitumor effect on hepatocellular carcinoma cells

To achieve specific and potent antitumor effect of hepatocyte carcinoma cells, replication defective adenoviral vectors, namely rAd/AFP-amiRG, rAd/AFP-amiRE and rAd/AFP-amiRP, were constructed which were armed with artificial microRNAs (amiRs) targeting essential functional genes glyceraldehyde-3-phosphate dehydrogenase, eukaryotic translation initiation factor 4E and DNA polymerase α respectively under the control of a recombinant promoter comprised of human α-fetoprotein enhancer and basal promoter. The AFP enhancer/promoter showed specific high transcription activity in AFP-positive HCC cells Hep3B, HepG2 and SMMC7721, while low in AFP-negative cell Bcap37. All artificial microRNAs exhibited efficient knockdown of target genes. Decreased ATP production and protein synthesis was observed in rAd/AFP-amiRG and rAd/AFP-amiRE treated HCC cells. All three recombinant adenoviruses showed efficient blockage of cell cycle progression and significant suppression of HCC cells in vitro. In nude mice model bearing Hep3B xenograft, administration of rAd/AFP-amiRG showed potent antitumor effect. The strategy of tumor-specific knockdown of genes essential for cell survival and proliferation may suggest a novel promising approach for HCC gene therapy.

DNA Polymerases as targets for gene therapy of hepatocellular carcinoma

Background

Hepatocyte carcinoma (HCC) is one of the most common malignancies worldwide. Despite many achievements in diagnosis and treatment, HCC mortality remains high due to the malignant nature of the disease. Novel approaches, especially for targeted therapy, are being extensively explored. Gene therapy is ideal for such purpose for its specific expression of exogenous genes in HCC cells driven by tissue-specific promoter. However strategies based on correction of mutations or altered expressions of genes responsible for the development/progression of HCC have limitations because these aberrant molecules are not presented in all cancerous cells. In the current work, we adopted a novel strategy by targeting the DNA replication step which is essential for proliferation of every cancer cell.

Methods

A recombinant adenovirus with alpha fetoprotein (AFP) promoter-controlled expressions of artificial microRNAs targeting DNA polymerases α, δ, ε and recombinant active Caspase 3, namely Ad/AFP-Casp-AFP-amiR, was constructed.

Results

The artificial microRNAs could efficiently inhibit the expression of the target polymerases in AFP-positive HCC cells at both RNA and protein levels, and HCC cells treated with the recombinant virus Ad/AFP-Casp-AFP-amiR exhibited significant G0/1 phase arrest. The proliferation of HCC cells were significantly inhibited by Ad/AFP-Casp-AFP-amiR with increased apoptosis. On the contrary, the recombinant adenovirus Ad/AFP-Casp-AFP-amiR did not inhibit the expression of DNA polymerases α, δ or ε in AFP-negative human normal liver cell HL7702, and showed no effect on the cell cycle progression, proliferation or apoptosis.

Conclusions

Inhibition of DNA polymerases α, δ and ε by AFP promoter-driven artificial microRNAs may lead to effective growth arrest of AFP-positive HCC cells, which may represent a novel strategy for gene therapy by targeting the genes that are essential for the growth/proliferation of cancer cells, avoiding the limitations set by any of the individually altered gene.

Tumor-specific suicide gene therapy for hepatocellular carcinoma by transcriptionally targeted retroviral replicating vectors

Replicating virus vectors are attractive tools for anticancer gene therapy, but the potential for adverse events due to uncontrolled spread of the vectors has been a major concern. To design a tumor-specific retroviral replicating vector (RRV), we replaced the U3 region of the RRV ACE-GFP with a regulatory sequence consisting of the hepatitis B virus enhancer II (EII) and human α-fetoprotein (AFP) core promoter to produce ACE-GFP-EIIAFP, a hepatocellular carcinoma (HCC)-targeting RRV. Similar to ACE-GFP, ACE-GFP-EIIAFP exhibited robust green fluorescent protein (GFP) expression in HCC cells and, most importantly, it exhibited HCC-specific replication and did not replicate in non-HCC tumor cells or normal liver cells. We sequenced the promoter region of ACE-GFP-EIIAFP collected from serial infection cycles to examine the genomic stability of the vector during its replicative spread, and found that the vector could retain the hybrid promoter in the genome for at least six infection cycles. In vitro studies revealed that ACE-CD-EIIAFP and ACE-PNP-EIIAFP, which express the yeast cytosine deaminase and Escherichia coli purine nucleoside phosphorylase, respectively, exert a highly potent cytotoxic effect on HCC cells in the presence of their respective prodrugs. In vivo, ACE-CD-EIIAFP-mediated suicide gene therapy efficiently suppressed HCC tumor growth and no detectable RRV signal was observed in extratumoral tissues. These results suggest that the tumor-specific, suicide-gene-encoding RRV may fulfill the promise of retroviral gene therapy for cancer.

TGF- β Signaling Cooperates with AT Motif-Binding Factor-1 for Repression of the α -Fetoprotein Promoter

α-Fetoprotein (AFP) is known to be highly produced in fetal liver despite its barely detectable level in normal adult liver. On the other hand, hepatocellular carcinoma often shows high expression of AFP. Thus, AFP seems to be an oncogenic marker. In our present study, we investigated how TGF-β signaling cooperates with AT motif-binding factor-1 (ATBF1) to inhibit AFP transcription. Indeed, the expression of AFP mRNA in HuH-7 cells was negatively regulated by TGF-β signaling. To further understand how TGF-β suppresses the transcription of the AFP gene, we analyzed the activity of the AFP promoter in the presence of TGF-β. We found that the TGF-β signaling and ATBF1 suppressed AFP transcription through two ATBF1 binding elements (AT-motifs). Using a heterologous reporter system, both AT-motifs were required for transcriptional repression upon TGF-β stimulation. Furthermore, Smads were found to interact with ATBF1 at both its N-terminal and C-terminal regions. Since the N-terminal (ATBF1N) and C-terminal regions of ATBF1 (ATBF1C) lack the ability of DNA binding, both truncated mutants rescued the cooperative inhibitory action by the TGF-β signaling and ATBF1 in a dose-dependent manner. Taken together, these findings indicate that TGF-β signaling can act in concert with ATBF1 to suppress the activity of the AFP promoter through direct interaction of ATBF1 with Smads.

Recent topics on α-fetoprotein

Zinc-fingers and homeoboxes 2 (ZHX2) and zinc-finger and BTB domain containing 20 (ZBTB20) repress the postnatal expression of α-fetoprotein (AFP) by interacting with the AFP gene promoter regions. ZHX2 inhibits the expression of AFP and cyclins A and E. ZBTB20 is negatively regulated by CUX1, which promotes cell-cycle progression, suggesting that AFP reactivation is closely linked to hepatocyte proliferation. A slight elevation in the serum AFP level often occurs in patients with chronic hepatitis C in the absence of hepatocellular carcinoma (HCC) and is an independent risk factor for HCC development to complement the fibrosis stage. In addition, the sustained elevation of AFP after interferon therapy is a risk factor of HCC development. AFP levels are clinically useful in predicting the outcomes of liver transplantation and sorafenib therapy for HCC patients. A low preoperative AFP level is a predictor of long-term survival and is associated with a low recurrence rate of HCC after liver transplantation. AFP response (≥20% decrease in AFP during 6-8 weeks of treatment) rather than radiological outcomes is a significant prognostic factor for survival in sorafenib-treated HCC patients. Highly sensitive Lens culinaris agglutinin-reactive AFP (AFP-L3) is 5-10 times more sensitive than conventional AFP-L3, and useful for early detection of HCC in patients with total AFP below 20 ng/mL.

Hypervascular hepatocellular carcinoma: correlation between biologic features and signal intensity on gadoxetic acid-enhanced MR images

PURPOSE

To analyze the correlation among biologic features, tumor marker production, and signal intensity at gadoxetic acid-enhanced MR imaging in hepatocellular carcinomas (HCCs).

MATERIALS AND METHODS

Institutional ethics committee approval and informed consent were obtained for this retrospective study. From April 2008 to September 2011, 180 surgically resected HCCs in 180 patients (age, 65.0 years ± 10.3 [range, 34-83 years]; 138 men, 42 women) were classified as either hypointense (n = 158) or hyperintense (n = 22) compared with the signal intensity of the background liver on hepatobiliary phase gadoxetic acid-enhanced MR images. Pathologic features were analyzed and a fetoprotein (AFP) and protein induced by vitamin K absence or antagonist-II (PIVKA-II) production were compared by means of serum analysis and immunohistochemical staining. Recurrence and survival rates were also evaluated. The Mann-Whitney and Pearson correlation tests were used for statistical analysis.

RESULTS

The grade of differentiation was higher (P = .028) and portal vein invasion was less frequent in hyperintense HCCs (13.6%) than in hypointense HCCs (36.7%) (P = .039). The serum levels of AFP, Lens culinaris agglutinin reactive fraction of AFP, and PIVKA-II were lower in hyperintense than in hypointense HCCs (P = .003, .004, and .026, respectively). Immunohistochemical AFP and PIVKA-II expression were lower in hyperintense than in hypointense HCCs (both P < .001). The recurrence rate was lower in hyperintense than in hypointense HCCs (P = .039).

CONCLUSION

The results suggest that hyperintense HCCs on gadoxetic acid-enhanced MR images are less aggressive than hypointense HCCs.

SUPPLEMENTAL MATERIAL

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12120226/-/DC1.

Analysis of biodistribution and engraftment into the liver of genetically modified mesenchymal stromal cells derived from adipose tissue

Presently, orthotopic liver transplant is the major therapeutic option for patients affected by primary liver diseases. This procedure is characterized by major invasive surgery, scarcity of donor organs, high costs, and lifelong immunosuppressive treatment. Transplant of hepatic precursor cells represents an attractive alternative. These cells could be used either for allogeneic transplantation or for autologous transplant after ex vivo genetic modification. We used stromal cells isolated from adipose tissue (AT-SCs) as platforms for autologous cell-mediated gene therapy. AT-SCs were transduced with lentiviral vectors expressing firefly luciferase, allowing for transplanted cell tracking by bioluminescent imaging (BLI). As a complementary approach, we followed circulating human α1-antitrypsin (hAAT) levels after infusion of AT-SCs overexpressing hAAT. Cells were transplanted into syngeneic mice after CCl(4)-induced hepatic injury. Luciferase bioluminescence signals and serum hAAT levels were measured at different time points after transplantation and demonstrate persistence of transplanted cells for up to 2 months after administration. These data, along with immunohistochemical analysis, suggest engraftment and repopulation of injured livers by transplanted AT-SCs. Moreover, by transcriptional targeting using cellular tissue-specific regulatory sequences, we confirmed that AT-SCs differentiate towards a hepatogenic-like phenotype in vitro and in vivo. Additionally, in transplanted cells reisolated from recipient animals' livers, we detected activation of the α-fetoprotein (AFP) promoter. This promoter is normally transcriptionally silenced in adult tissues but can be reactivated during liver regeneration, suggesting commitment towards hepatogenic-like differentiation of engrafted cells in vivo. Our data support AT-SC-mediated gene therapy as an innovative therapeutic option for disorders of liver metabolism.

Non-invasive monitoring of hepatocellular carcinoma in transgenic mouse with bioluminescent imaging

A small animal imaging system for hepatocellular carcinoma (HCC)-specific reporter gene expression will enable monitoring of carcinogenesis or therapeutic intervention in vivo. Transgenic mouse was developed in which firefly luciferase (fLuc) expression was controlled by the AFP enhancer/promoter. The bioluminescent signals of the transgenic neonates were strong at their liver region and decreased after birth. Bioluminescent imaging (BLI) of a transgenic mouse treated with N-nitrosodiethylamine revealed distinct fLuc activity in the liver and an increased pattern with time. The transgenic mouse model can be used to monitor AFP producing HCC by a chemical carcinogen in a live animal by BLI.

Primary hepatoid adenocarcinoma of the uterine corpus: A case report with immunohistochemical study for expression of liver-enriched nuclear factors

We report a case of hepatoid adenocarcinoma of the uterus in an 86-year-old woman. Serum AFP was elevated (7824ng/ml) on admission. The surgical specimen obtained by simple hysterectomy and bilateral salpingo-oophorectomy showed an exophytic tumor, 10.5cm×6.0cm×3.7cm in size, in the uterine corpus. Microscopically, tumor cells proliferated in trabecular or cord-like arrangement, which was considered as "hepatoid appearance". An adenocarcinomatous component was intermingled. The expressions of liver-enriched transcription factors, hepatocyte nuclear factor (HNF)-1β, HNF-3, HNF-4α, and CCAAT/enhancer binding protein (C/EBP)-β, were investigated in the present case and in 19 cases of endometrioid adenocarcinoma (11 cases of Grade 2 and 8 cases of Grade 3), because these nuclear factors are involved in embryonal hepatogenesis. HNF-4α was diffusely positive in the present case, but negative in all cases of endometrioid adenocarcinoma. HNF-3 and C/EBP-β were positive for the present case and control adenocarcinoma cases (HNF-3, 36.8% and C/EBP-β, 84.2%). HNF-1β was negative for both the present case and endometrioid adenocarcinomas. This is the first report to demonstrate HNF-4α expression in this rare uterine tumor.

HNF1α and CDX2 transcriptional factors bind to cadherin-17 (CDH17) gene promoter and modulate its expression in hepatocellular carcinoma

Cadherin-17 (CDH17) belongs to the cell adhesion cadherin family with a prominent role in tumorigenesis. It is highly expressed in human hepatocellular carcinoma (HCC) and is proposed to be a biomarker and therapeutic molecule for liver malignancy. The present study aims to identify the transcription factors which interact and regulate CDH17 promoter activity that might contribute to the up-regulation of CDH17 gene in human HCC. A 1-kb upstream sequence of CDH17 gene was cloned and the promoter activity was studied by luciferase reporter assay. By bioinformatics analysis, deletion and mutation assays, and chromatin immunoprecipitation studies, we identified hepatic nuclear factor 1α (HNF1α) and caudal-related homeobox 2 (CDX2) binding sites at the proximal promoter region which modulate the CDH17 promoter activities in two HCC cell lines (Hep3B and MHCC97L). A consistent down-regulation of CDH17 and the two transcriptional activators (HNF1α and CDX2) expression was found in the liver of mouse during development, as well as in human liver cancer cells with less metastatic potential. Suppression of HNF1α and CDX2 expression by small interfering RNA (siRNA) significantly down-regulated expressions of CDH17 and its downstream target cyclin D1 and the viability of HCC cells in vitro. In summary, we identified the minimal promoter region of CDH17 that is regulated by HNF1α and CDX2 transcriptional factors. The present findings enhance our understanding on the regulatory mechanisms of CDH17 oncogene in HCC, and may shed new insights into targeting CDH17 expression as potential therapeutic intervention for cancer treatment.

A unique chromatin signature uncovers early developmental enhancers in humans

Cell-fate transitions involve the integration of genomic information encoded by regulatory elements, such as enhancers, with the cellular environment. However, identification of genomic sequences that control human embryonic development represents a formidable challenge. Here we show that in human embryonic stem cells (hESCs), unique chromatin signatures identify two distinct classes of genomic elements, both of which are marked by the presence of chromatin regulators p300 and BRG1, monomethylation of histone H3 at lysine 4 (H3K4me1), and low nucleosomal density. In addition, elements of the first class are distinguished by the acetylation of histone H3 at lysine 27 (H3K27ac), overlap with previously characterized hESC enhancers, and are located proximally to genes expressed in hESCs and the epiblast. In contrast, elements of the second class, which we term 'poised enhancers', are distinguished by the absence of H3K27ac, enrichment of histone H3 lysine 27 trimethylation (H3K27me3), and are linked to genes inactive in hESCs and instead are involved in orchestrating early steps in embryogenesis, such as gastrulation, mesoderm formation and neurulation. Consistent with the poised identity, during differentiation of hESCs to neuroepithelium, a neuroectoderm-specific subset of poised enhancers acquires a chromatin signature associated with active enhancers. When assayed in zebrafish embryos, poised enhancers are able to direct cell-type and stage-specific expression characteristic of their proximal developmental gene, even in the absence of sequence conservation in the fish genome. Our data demonstrate that early developmental enhancers are epigenetically pre-marked in hESCs and indicate an unappreciated role of H3K27me3 at distal regulatory elements. Moreover, the wealth of new regulatory sequences identified here provides an invaluable resource for studies and isolation of transient, rare cell populations representing early stages of human embryogenesis.

Alpha-fetoprotein gene polymorphisms and risk of HCC and cirrhosis

BACKGROUND

Elevated level of alpha fetoprotein (AFP) is found in approximately 60% of hepatocellular carcinoma (HCC) cases. Other liver diseases including cirrhosis and chronic hepatitis are related with an increased level of AFP. The regulation of AFP gene expression has been relatively less studied although the gene has been suggested to play a role in HCC development. This study aimed at identifying genetic variations in AFP that might be associated with the presence of HCC and cirrhosis among ethnic Indonesians.

METHODS

Direct DNA sequencing was carried out to sequence AFP promoter, exons, and 3' untranslated region (UTR) in DNA samples isolated from 119 HCC, 119 cirrhosis and 105 control subjects. For each sample serum AFP level was determined and association studies with single nucleotide polymorphisms (SNPs) and haplotypes were performed.

RESULTS

In this study we identified 47 SNPs in the AFP gene. Statistically significant associations with HCC and cirrhosis were detected for six individual SNPs in the AFP promoter, AFP intron 1 and intron 2 (rs6834059, rs3796678, rs3796677, rs3796676, rs28532518 and rs4646038). Furthermore, we identified two SNPs in AFP intron 7 and 3'UTR, rs2298839 and rs10020432, which are associated with increased risk of cirrhosis.

CONCLUSION

Genetic variants in the AFP gene may be associated with HCC and cirrhosis risk for ethnic Indonesians.

Isolation of human fetal liver progenitors and their enhanced proliferation by three-dimensional coculture with endothelial cells

Liver progenitor cells, characterized by the coexpression of biliary and hepatocyte lineage markers and the ability to form colonies in culture, were isolated by flow cytometry from primary human fetal livers. These prospectively isolated liver progenitor cells supported hepatitis D virus infection, expressed, and produced albumin and alpha-fetoprotein, as tracked by albumin- and alpha-fetoprotein-driven lentiviral promoter reporter constructs and measured by ELISA, respectively. Coculture in three-dimensional (3D) fibrin gel with endothelial cells resulted in the formation of vascular structures by the endothelial cells and increased proliferation of liver progenitors. The enhanced proliferation of liver progenitors that was observed when liver progenitors and endothelial cells were cultured in direct contact was not achieved when liver progenitors and endothelial cells were cultured on adjacent but separate matrices and when they were cultured across transwell membranes. In conclusion, coculture of liver progenitors and endothelial cells in three-dimensional matrix resulted in enhanced liver progenitor proliferation and function. This coculture methodology offers a novel coculture system that could be applied for the development of engineered liver tissues.

Radioiodine gene therapy of hepatocellular carcinoma targeted human alpha fetoprotein

INTRODUCTION

We conducted a molecular imaging and gene therapy method in alpha-fetoprotein (AFP)-producing hepatocellular carcinoma (HCC) by tumor-specific expression of the human sodium/iodide symporter (hNIS) using an AFP promoter.

METHODS

The tumor-specific expression of hNIS gene by the AFP enhancer/promoter was constructed as pcDNA3-AFP/hNIS. The pcDNA3-AFP/hNIS was stably transfected to human HCC (Huh-7/AN) and rat glioma cells (C6/AN). Functional hNIS expression was confirmed by radioiodine uptake. The mRNA and protein-expression level of hNIS were measured. Biodistribution of 131I was evaluated, and scintigraphic images of 99mTc were obtained in xenografted mice. A clonogenic assay was performed by 131I. And, the in vivo therapeutic effect of 131I was evaluated in xenografted mice.

RESULTS

In Huh-7/AN cells, iodine was highly accumulated and completely blocked by perchlorate. The protein and mRNA expression levels were correlated with iodine uptake. Radioiodine uptake in Huh-7/AN tumors was higher than those of control tumors and clearly visualized. The survival rate was significantly decreased in Huh-7/AN cells by 131I. Moreover, a growth of Huh-7/AN tumors was inhibited by 131I in mice.

CONCLUSIONS

AFP-producing hepatoma can be targeted and treated with radionuclides and hNIS, using AFP enhancer/promoter. This targeted hNIS gene therapy and molecular imaging have the potential to be used in the management of AFP-producing HCC.

Transcription factor HNF and hepatocyte differentiation

To know the precise mechanisms underlying the life or death and the regeneration or differentiation of cells would be relevant and useful for the development of a regenerative therapy for organ failure. Liver-specific gene expression is controlled primarily at a transcriptional level. Studies on the transcriptional regulatory elements of genes expressed in hepatocytes have identified several liver-enriched transcriptional factors, including hepatocyte nuclear factor (HNF)-1, HNF-3, HNF-4, HNF-6 and CCAAT/enhancer binding protein families, which are key components of the differentiation process for the fully functional liver. The transcriptional regulation by these HNFs, which form a hierarchical and cooperative network, is both essential for hepatocyte differentiation during mammalian liver development and also crucial for metabolic regulation and liver function. Among these liver-enriched transcription factors, HNF-4 is likely to act the furthest upstream as a master gene in transcriptional cascade and interacts with other liver-enriched transcriptional factors to stimulate hepatocyte-specific gene transcription. A link between the extracellular matrix, changes in cytoskeletal filament assembly and hepatocyte differentiation via HNF-4 has been shown to be involved in the transcriptional regulation of liver-specific gene expression. This review provides an overview of the roles of liver-enriched transcription factors in liver function.

Effects of extracellular matrixes and growth factors on the hepatic differentiation of human embryonic stem cells

Hepatocytes derived from human embryonic stem cells (hESCs) are a potential cell source for regenerative medicine. However, the definitive factors that are responsible for hepatic differentiation of hESCs remain unclear. We aimed to evaluate the effects of various extracellular matrixes and growth factors on endodermal differentiation and to optimize the culture conditions to induce hepatic differentiation of hESCs. The transgene vector that contained enhanced green fluorescent protein (EGFP) under the control of human alpha-fetoprotein (AFP) enhancer/promoter was transfected into hESC lines. The transgenic hESCs were cultured on extracellular matrixes (collagen type I, laminin, and Matrigel) in the presence or absence of growth factors including hepatocyte growth factor (HGF), bone morphogenetic protein 4, fibroblast growth factor 4, all-trans-retinoic acid, and activin A. The expression of AFP-EGFP was measured by flow cytometry. The culture on Matrigel-coated dishes with 100 ng/ml activin A showed 19.5% of EGFP-positive proportions. Moreover, the sequential addition of 100 ng/ml activin A and 20 ng/ml HGF resulted in 21.7% and produced a higher yield of EGFP-positive cells than the group stimulated by activin A alone. RT-PCR and immunocytochemical staining revealed these EGFP-positive cells to differentiate into mesendoderm-like cells by use of activin A and then into hepatic endoderm cells by use of HGF. Two other hESC lines also differentiated into endoderm on the hepatic lineage by our method. In conclusion, we therefore found this protocol to effectively differentiate multiple hESC lines to early hepatocytes using activin A and HGF on Matrigel.

A case of *-fetoprotein-producing pulmonary carcinoma with restricted expression of hepatocyte nuclear factor-4* in hepatoid foci: a case report with studies of previous cases

We report a case of *-fetoprotein (AFP)-producing pulmonary carcinoma with studies for messenger RNA (mRNA) expression of hepatocyte nuclear factor (HNF)-4*, which is a transcription factor that is highly expressed in the process of liver development. The patient was a 64-year-old man with a pulmonary tumor in his left lower lobe. Serum AFP was 673 ng/mL. The microscopic analysis of the surgical specimen revealed a large cell neuroendocrine carcinoma with occasional hepatoid foci. The competitive reverse transcriptase polymerase chain reaction analysis revealed that HNF-4* mRNA was expressed on the order of 10(2)- to 10(3)-fold more abundantly than control pulmonary carcinomas and normal lung tissues. In addition, AFP and HNF-4* expression was restricted in hepatoid foci. Two previously reported cases of AFP-producing pulmonary carcinoma were also positive, whereas all 18 control pulmonary carcinomas were negative for HNF-4*. These findings suggest that aberrant expression of HNF-4* is implicated in the emergence or maintenance of hepatoid foci in AFP-producing pulmonary carcinomas.

Identification of CCAAT enhancer binding protein α binding sites on the human α-fetoprotein gene

Development- and tissue-specific alpha-fetoprotein (AFP) gene expression is controlled by various transcription factors including hepatocyte nuclear factors (HNFs), and a number of cis-acting elements. We recently identified multiple CCAAT/enhancer binding protein (C/EBP) binding sites in the enhancer of the human AFP gene. In this study, we have identified and functionally characterized seven C/EBPalpha-binding sites in the promoter and enhancer regions. An electrophoretic mobility shift assay (EMSA) and DNase I footprinting analysis identified two and five C/EBPalpha-binding sites located in the promoter and enhancer regions, respectively. Chromatin immunoprecipitation analyses showed that C/EBPalpha binds both enhancer and promoter regions of the AFP gene in human AFP-producing hepatoma and stomach cancer cells, but not in non-AFP-producing cells. Reporter transfection assays showed that transcription was stimulated by C/EBPalpha binding to each of the elements. These results indicate that C/EBPalpha regulates AFP gene expression through direct binding to multiple sites in the human AFP gene in cultured human cells.

Expression of liver-enriched nuclear factors and their isoforms in alpha-fetoprotein-producing gastric carcinoma cells

Alpha-fetoprotein (AFP)-producing gastric cancer (AFP-GC) is a highly malignant variant of adenocarcinoma with aberrant hepatocellular phenotype. A detailed understanding of the regulation of its liver phenotype is lacking. Liver-enriched nuclear factors (LENFs) are implicated in the transcriptional regulation of AFP in the fetal liver. To investigate the regulatory role of LENFs in AFP-GCs, the expression of LENFs including CCAAT/enhancer binding protein (C/EBP)-beta, C/EBP-alpha, hepatocyte nuclear factor (HNF)-1alpha, HNF-1beta and HNF-4alpha was investigated in 3 cell lines of AFP-GC and 7 cell lines of control GC. The liver activating protein (LAP), an activating isoform of C/EBP-beta, was predominantly expressed in AFP-GCs, whereas the liver inhibitory protein (LIP), an inhibitory isoform of C/EBP-beta, predominated in the control GCs. HNF-1alpha was relatively suppressed in AFP-GCs. HNF-4alpha was expressed in one of three AFP-GC cell lines. C/EBP-alpha and HNF-1beta were expressed at the same levels in both cell types of GC. AFP-GCs expressed a set of hepatocyte-related proteins (e.g., transferrin and albumin) while they still retained the several glandular cell-related proteins (e.g., MUC2). The induction of LIP reduced transferrin expression and induced CEA expression in an AFP-GC line. Collecting these results, it was suggested that the contribution of LENFs, especially isoforms of C/EBP-beta, is possibly important in phenotypic regulation of AFP-GCs.