Transforming growth factor beta 1 differentially regulates alpha-fetoprotein and albumin in HuH-7 human hepatoma cells

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.

Effects of IFN-alpha on alpha-fetoprotein expressions in hepatocellular carcinoma cells

We investigated the effects of pegylated (PEG)-IFN-alpha2b on alpha-fetoprotein (AFP) expression as demonstrated by protein and mRNA levels in six human hepatocellular carcinoma (HCC) cell lines. The number of KIM-1 cells in culture with PEG-IFN-alpha2b decreased between 24 amd 240 h, whereas the levels of intracellular and secreted AFP per cellular protein increased (except at 192 h), with levels 1.9-fold and 2.9-fold higher at maximum, respectively, than cells without PEG-IFN-alpha2b (control). The mRNA level increased between 72 and 192 h, when the level was 3-fold higher than that of the control. In the 72-h culture with 40-5000 IU/mL PEG-IFN-alpha2b, there were dose-dependent increases in AFP protein and mRNA expression and dose-dependent decrease in cell number resulting from apoptosis and blockage of the cell cycle at the S-phase. The rate of fucosylated AFP in the cell lysate decreased in a dose-dependent and time-dependent manner. In the PEG-IFN-alpha2b culture of the other five HCC cell lines, cell proliferation was suppressed, but the expressions of AFP protein and mRNA increased in only two cell lines, and suppression of cell proliferation was not related to the increase in AFP expressions. Our findings demonstrated that PEG-IFN-alpha2b induces an increase in AFP expression at both the protein and mRNA levels.

Reversing hepatocellular carcinoma progression by using networked biological therapies

The liver is distinguished from other tissues by (a) its detoxifying function, (b) its resistance to apoptosis, and (c) its regenerative response to damage. Hepatocellular carcinoma arises when chronic insults, such as hepatitis or iron overload, constitutively activate this regenerative program. Here, we propose that the proliferative response of the liver to damage underlies the resistance of hepatocellular carcinoma to cytotoxic therapy, and that hepatocellular carcinoma growth should therefore be more readily controlled by using a networked combination of noncytotoxic interventions to interrupt the damage-inducible regenerative pathway. To this end, hepatocellular carcinoma boasts a wealth of potential drug targets, including viral replication, the antiapoptotic immunosuppressant alpha-fetoprotein, hepatic iron overload, inflammatory signaling, extracellular proteases, and growth factors. By blocking these positive feedback loops in parallel, and so returning the host environment to a more normal state, epigenetic repression of tumor-suppressor gene function may be reversed and tumor dormancy restored. Noncytotoxic maneuvers that short circuit damage resistance loops may thus represent an indirect form of gene therapy meriting incorporation into hepatocellular carcinoma clinical trials.

Transforming growth factor-beta1 as a useful serologic marker of small hepatocellular carcinoma

BACKGROUND

Although alpha-fetoprotein (AFP) is a useful serologic marker of hepatocellular carcinoma (HCC), it has been reported insufficiently sensitive in detecting small HCCs. Plasma transforming growth factor-beta1 (TGFbeta1) has been reported to be elevated in HCC patients compared with liver cirrhosis patients. It has been reported that TGFbeta1 mRNA was overexpressed in HCC, especially in patients with small HCC and well-differentiated HCC compared with patients with liver cirrhosis. The current study investigated the usefulness of TGFbeta1 compared with AFP in the diagnosis of small HCCs.

METHODS

Thirty-eight patients with small HCC (< or = 3 cm), 31 patients with liver cirrhosis only, and 23 normal volunteers were studied. Using plasma TGFbeta1 and serum AFP levels measured at the time of diagnosis, the sensitivities and specificities were calculated in the diagnosis of small HCCs.

RESULTS

Plasma TGFbeta1 and serum AFP levels were significantly higher in patients with small HCC than in those with liver cirrhosis. In diagnosing small HCCs, the cut-off values of plasma TGFbeta1 and serum AFP were 800 pg/mL and 200 ng/mL, respectively, where the specificities were over 95%. At the cut-off level of plasma TGFbeta1 and serum AFP, the sensitivities were 68% and 24%, respectively.

CONCLUSIONS

The current results suggest that TGFbeta1 may be a useful serologic marker in detecting HCCs earlier because it shows higher sensitivity than, with specificity as, AFP in the diagnosis of small HCCs.

Establishment of a testicular carcinoma cell line producing alpha-fetoprotein

OBJECTIVE

To characterize a newly established human testicular carcinoma cell line that continuously produces alpha-fetoprotein (AFP), and to investigate the effects of retinoic acid on AFP production.

MATERIALS AND METHODS

A 24-year-old man underwent a radical orchidectomy for a right testicular tumour and was found to have two separate metastatic lesions in the lungs, both of which were removed surgically. The cancer cells were isolated from one of the tumours, which was composed of undifferentiated germ cells and produced AFP; the cells were cultured in a monolayer. This cell line was designated as KU-MT.

RESULTS

The cell line was successfully maintained both in athymic nude mice and in culture. Histological examination showed that the xenografted tumours were composed of cells in the reticular, solid and glandular patterns of a yolk sac tumour, and of embryonal carcinoma cells. These cells immunostained positively for AFP. On electron microscopy, the extracellular deposition of a basement lamina-like substance, a typical feature of yolk sac tumour, was detected. The AFP production in mice correlated well with the tumour weight of the xenograft. The cultured KU-MT cells were oval to polygonal in morphology and grew exponentially, with a population doubling time of approximately 2 days. Chromosomal analysis showed a modal number of 57 with consistent structural abnormalities of +add(1)(p13), del(1)(q32), del(2)(q31), add(6) (q21), +add(9)(p22), add(11)(p15), and add(14)(p11). Reverse-transcription polymerase chain reaction analysis showed that the retinoic acid receptors (RAR)-alpha, RAR-gamma, and retinoid X receptor-alpha were present in the cells. The expression of AFP mRNA was up-regulated in response to all-trans-retinoic acid; treatment with this agent caused morphological changes and induced apoptosis in the cells.

CONCLUSIONS

This newly established cell line provides a reproducible model system that should offer a good insight into the differentiation of testicular carcinoma.

Human alpha-fetoprotein transcriptional regulatory sequences. Application to gene therapy

The AFP regulatory sequences are among the best known tumor-specific transcriptional regulators. A number of groups have demonstrated that a variety of genes can be expressed in an HCC-specific manner under the control of the AFP regulatory sequences in vitro and in vivo. It would appear that, with the development of a suitable delivery system, HCC-directed gene therapy using the AFP regulatory sequences holds a promising future.

Effect of simvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, on alpha-fetoprotein gene expression through interaction with the ras-mediated pathway

BACKGROUND/AIMS

The ras proto-oncogene encodes a small GTP-binding protein (Ras) which regulates cell growth and differentiation by relaying signals from the cell surface to the nucleus. In the present study, the role of Ras signal transduction pathway in alpha-fetoprotein (AFP) gene expression was evaluated in HuH-7 human hepatoma cells using simvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, which blocks Ras function through inhibition of farnesylation, and the ras(val-12) expression vector.

METHODS

The HuH-7 cells were treated with simvastatin (10 micromol/l), or both simvastatin and mevalonate (300 micromol/l), and numbers of viable cells were counted after treatment. To elucidate the effects of simvastatin on AFP gene expression and the interactive effect of simvastatin on Ras signal transduction pathway, Northern blotting and transient chloramphenicol acetyltransferase plasmid transfection assays were performed.

RESULTS

Cell growth was inhibited by simvastatin, and this growth inhibition was restored by addition of mevalonate. Levels of AFP mRNA but not albumin mRNA were elevated by simvastatin in a dose-dependent manner (1-10 micromol/l). AFP promoter and enhancer activities were stimulated by simvastatin. In contrast, both activities were repressed by transfection with the ras(val-12) expression vector. The ras(val-12)-mediated repression was restored by simvastatin and returned to the repressed level by simvastatin plus mevalonate.

CONCLUSIONS

These results indicate that the Ras signal transduction pathway functions to down-regulate the AFP gene transcription in human hepatoma cells.

Utilization of variant-type of human alpha-fetoprotein promoter in gene therapy targeting for hepatocellular carcinoma

We previously reported that the retroviral vector (LNAFW0.3TK) expressing the herpes simplex thymidine kinase (HSVtk) gene under the control of the 0.3 kb human alpha-fetoprotein (AFP) promoter provided the ganciclovir (GCV)-mediated cytotoxicity in the high AFP-producing (HuH-7) but not in the low AFP-producing (huH-1/cl.2) human hepatoma cells. In the present study, we constructed the retroviral vector (LNAFM0.3TK) in which the HSVtk gene expression is regulated by the variant-type of the 0.3 kb human AFP promoter with a G-to-A substitution at nucleotide -119, a point mutation responsible for hereditary persistence of human AFP and the vector was applied to three human hepatoma cell lines HuH-7, huH-1/cl.2 and intermediate AFP-producing cells (PLC/PRF/5). By the reporter gene transfection assay, the activity of the variant-type of the promoter was much higher than that of the wild-type of the promoter in both HuH-7 and huH-1/cl.2 cells. Consistent with this, LNAFM0.3TK infection could sensitize huH-1/cl.2 cells, as well as HuH-7 and PLC/PRF/5 cells to GCV, but did not affect cell growth of nonhepatoma cells (HeLa). In addition, the bystander effect was achieved more efficiently by LNAFM0.3TK infection than LNAFW0.3TK infection in HuH-7 cells. These results suggest that the variant-type of the human AFP promoter ensures the therapeutic gene expression in gene therapy particularly for the low AFP-producing hepatoma cells.

Retinoic acid mediates down-regulation of the alpha-fetoprotein gene through decreased expression of hepatocyte nuclear factors

alpha-Fetoprotein (AFP), a protein highly induced during fetal liver development, is down-regulated by retinoids in the human hepatoma cell line Hep3B, in contrast to up-regulation observed in other cell types. Previously, we have documented that such up-regulation involves direct effects through cis-retinoid X receptor-binding sites in the AFP enhancer. In this report, we show a distinctive effect of all-trans-retinoic acid (RA) in Hep3B cells. RA caused a marked decrease in AFP transcripts. Deletion analysis of the upstream regulatory region of the AFP gene revealed that cis-acting sites required for down-regulation resided near the promoter. Gel mobility shift assays for factors binding to key elements in the AFP promoter region demonstrated that hepatocyte nuclear factor (HNF) 1 binding was diminished in nuclear extracts from RA-treated cells. In addition, HNF4, which is not known to bind to the AFP promoter but does regulate HNF1, was also diminished. The levels of HNF1 and HNF4 mRNA were also decreased following RA treatment. AFP promoter-chloramphenicol acetyltransferase transient transfection assays demonstrated that the level of HNF1 had a direct impact on basal transcription as well as RA-mediated down-regulation of the AFP gene, and that co-transfection of HNF1 and HNF4, but not transfection of either factor alone, reversed the RA-mediated inhibition. Taken together these data point to an interaction among the RA, HNF1, and HNF4 signals, which is reflected in decreased expression of AFP.

Clinical relevance of transforming growth factor-beta 1 in the urine of patients with hepatocellular carcinoma

To assess the clinical relevance of transforming growth factor-beta 1 (TGF-beta 1) in the urine of patients with hepatocellular carcinoma (HCC), TGF-beta 1 was measured, by radioimmunoassay, in 140 patients with HCC, 50 cirrhotic patients, 30 patients with chronic active hepatitis, and 50 healthy controls. The results indicate that there were significantly increased urinary TGF-beta 1 levels in patients with HCC. Raised TGF-beta 1 levels were associated, in a dose-related fashion, with increased risk for development of HCC (odds ratio, 1.05, 95% confidence interval, 1.03-1.07). HCC patients with raised TGF-beta 1 levels had shorter survival than those with normal TGF-beta 1 levels (p = 0.038). TGF-beta 1 levels decreased after successful anticancer therapy (p < 0.0001). There was an inverse correlation between TGF-beta 1 and serum alpha-fetoprotein (AFP) (r = -0.199, p < 0.04). Receiver operating characteristics (ROC) curve analysis indicated that parallel determination of TGF-beta 1 and AFP significantly increased the sensitivity and diagnostic accuracy, with a high specificity. In conclusion, raised urinary TGF-beta 1 was associated with HCC development. It is a predictor of poor prognosis, and a tumor marker for diagnosis and therapeutic follow-up of HCC.

Urinary transforming growth factor-beta 1 in relation to serum alpha-fetoprotein in hepatocellular carcinoma

BACKGROUND

Our aim was to assess the relationship between transforming growth factor beta 1 (TGF-beta 1) and alpha-fetoprotein (AFP) levels in hepatocellular carcinoma (HCC).

METHODS

Urinary TGF-beta 1 and serum AFP were determined in 123 HCC patients, 50 patients with chronic liver disease (CLD), and 50 healthy controls.

RESULTS

Both TGF-beta 1 and AFP levels were higher in HCC patients than in CLD patients or controls (each, P = 0.0001). There was a negative correlation between TGF-beta 1 and logAFP (r = -0.196, P = 0.029). Multivariate analysis indicated that TGF-beta 1 and AFP were associated with an increased risk of HCC development. By receiver-operating characteristic curve analysis, determination of AFP and TGF-beta 1 in parallel significantly increased the sensitivity and diagnostic accuracy in detecting HCC.

CONCLUSION

Increased urinary TGF-beta 1 level can be used as a complementary marker to AFP for detection of HCC with low AFP production.

Elevated urinary transforming growth factor-beta1 level as a tumour marker and predictor of poor survival in cirrhotic hepatocellular carcinoma

To assess the clinical relevance of transforming growth factor-beta1 (TGF-beta1) in hepatocellular carcinoma (HCC), urinary TGF-beta1 and serum alpha-fetoprotein (AFP) were determined in 94 patients with cirrhotic HCC, 94 age- and sex-matched patients with cirrhosis alone and 50 healthy adults. TGF-beta1 level in HCC was higher than in cirrhosis alone or in healthy controls (each P = 0.0001). There is an inverse correlation between TGF-beta1 and AFP levels (r = -0.292, P = 0.004). Significantly higher TGF-beta1 level was found in HCC patients with worsening Child-Pugh stages, diffuse HCC, tumour size > 3 cm, multilobular tumour and AFP < or = 20 ng ml(-1). TGF-beta1 level decreased after complete treatment with transcatheter arterial chemoembolization (P = 0.0001). The median survival in HCC patients with raised TGF-beta1 was shorter than those with normal TGF-beta1 (P = 0.018). Multivariate analysis indicated that TGF-beta1 and AFP were significantly correlated with the presence of HCC. In addition, TGF-beta1 could be used as a diagnostic marker for HCC, particularly in tumours with low AFP production. In conclusion, elevated urinary TGF-beta1 level is a tumour marker and predictor of poor survival for cirrhotic HCC.

Clinical evaluation of urinary transforming growth factor-beta1 and serum alpha-fetoprotein as tumour markers of hepatocellular carcinoma

To evaluate the diagnostic application of urinary transforming growth factor-beta1 (TGF-beta1) and serum alpha-fetoprotein (AFP) levels in hepatocellular carcinoma (HCC), TGF-beta1 and AFP were determined in 94 patients with cirrhotic HCC and in 94 sex- and age-matched patients with cirrhosis alone. TGF-beta1 and AFP levels in HCC were higher than in cirrhosis alone (P = 0.0001). There is an inverse correlation between TGF-beta1 and log AFP (r = -0.292, P = 0.004). Multivariate analysis indicated that TGF-beta1 and AFP were closely associated, in a dose-related fashion, with the development of HCC. Receiver-operating characteristic (ROC) curves were used to determine the optimal cut-off values of TGF-beta1 (50 microg g(-1) creatinine) and AFP (100 ng ml(-1)). Both TGF-beta1 and AFP showed a high specificity (99%) and positive likelihood ratio. The sensitivity was 53.1% for TGF-beta1 and 55.3% for AFP. The determination of both markers in parallel significantly increased the diagnostic accuracy (90.1%) and sensitivity (84%), with a high specificity (98%) and positive likelihood ratio (40.0). In conclusion, TGF-beta1 and AFP are independent tumour markers of HCC and may be used as complementary tumour markers to discriminate HCC from cirrhosis.

Circulating intercellular adhesion molecule 1 predicts non-specific elevation of alpha 1-fetoprotein

Molecules governing cellular interactions have been suggested to be involved in the spurious elevation of alpha 1-fetoprotein (AFP) in non-neoplastic liver disease. To explore this controversial issue, we measured AFP, circulating intercellular adhesion molecule 1 (cICAM-1), and common liver function tests in 111 patients (71 male, 40 female). Eighty-four patients had non-neoplastic chronic liver disease and 27 had hepatocellular carcinoma. The concentration of cICAM-1 was determined immunoenzymatically. In patients with non-neoplastic chronic liver disease, univariate analysis demonstrated a significant correlation between AFP and cholinesterase (R = -0.397, P < 0.001), aspartate aminotransferase (R = 0.421, P < 0.001), bilirubin (R = 0.231, P < 0.05) and cICAM-1 (R = 0.430, P < 0.001). Multivariate analysis among these variables and AFP indicated cICAM-1 to be the strongest independent predictor of AFP. We conclude that cICAM-1 compares favourably with liver function tests in predicting non-specific AFP variations in non-neoplastic chronic liver disease, suggesting a link between targeting of the inflammatory damage to the hepatocyte and development of neoplasia.

Alpha-fetoprotein and the acute phase response. A study using acute pelvic inflammatory disease as a model system

Alpha-fetoprotein (AFP) is used as a tumor marker for hepatomas and germ cell tumors. In healthy non-pregnant adults the serum concentration (S-AFP) is very low and we examined whether it was affected when the acute phase response was activated, using patients with acute pelvic inflammatory disease (PID) as a model system. In 70 PID patients the median S-AFP was 1.2 kIU/l (range: 0.5-5.9 kIU/l), within the normal range. S-AFP did not correlate with the clinical grade of disease nor with the serum concentrations of acute phase reactants and albumin. Thus, S-AFP is not significantly affected by activation of the acute phase response and presence of infection should not per se interfere with the use of S-AFP as a tumor marker. However, a negative correlation was found with the serum concentration of alpha-2-macroglobulin (P = 0.05), but whether this has any biological significance remains to be clarified.

Changes of antigen expression on human hepatoma cell lines caused by sodium butyrate, a differentiation inducer

We have previously reported the effect of a differentiation inducer, sodium butyrate (SB), on human hepatocellular carcinoma (HCC) cell lines, demonstrating that it was a potent inducer of differentiation. In the present study, we investigated the alteration in expression of an antigen defined by a murine monoclonal antibody, H2, as well as alterations in the expression of other antigens, on the HCC cell lines HCC-T, HCC-M, and PLC/PRF/5, since it is known that specific antigenic changes occur during the differentiation of leukemic cells. The expression of the antigen defined by H2 increased immunocytochemically on HCC-T, HCC-M, and PLC/PRF/5 during treatment with SB. A flowcytometric study showed that almost all the HCC-T and HCC-M cells treated with SB highly expressed this antigen after 5 days' treatment. The antigen expression detected by H2 decreased after the removal of SB from the medium. On the other hand, antigen expression detected by another monoclonal antibody, 5C11, was not changed by this treatment. The expression of intracellular adhesion molecule (ICAM)-1 in HCC-T increased slightly, but that of beta 2-microglobulin and HLA-DR did not change. These results demonstrated that some antigen expression was changed by SB treatment and that the antigen defined by H2 seemed to be highly expressed on human HCC cells in the differentiated state.

Reciprocal regulation of alpha-fetoprotein and albumin gene expression by butyrate in human hepatoma cells

BACKGROUND/AIMS

Butyrate, a product of colonic bacterial flora, functions as an antiproliferative agent and induces cell differentiation in a variety of cell types. In the present study, the effects of butyrate on cell growth and expression of alpha-fetoprotein (AFP) and albumin genes in HuH-7 human hepatoma cells were investigated.

METHODS

The HuH-7 cells were treated with sodium butyrate (0-1 mmol/L), and numbers of viable cells were counted at 24, 48, and 72 hours after treatment. To elucidate the effects of sodium butyrate on AFP and albumin gene expression, Northern blotting and transient chloramphenicol acetyltransferase plasmid transfection experiments were performed.

RESULTS

Cell growth was dose dependently inhibited by sodium butyrate. By Northern blot analysis, the level of AFP messenger RNA was reduced by treatment with sodium butyrate, whereas the level of albumin messenger RNA was elevated by this treatment. In transient chloramphenicol acetyltransferase plasmid transfection experiments, sodium butyrate repressed the AFP promoter activity but did not change the AFP enhancer or silencer activities. In contrast, the albumin promoter activity was stimulated by sodium butyrate.

CONCLUSIONS

These results suggest that butyrate leads to the reciprocal differentiating regulation of AFP and albumin gene expression at the transcriptional level in human hepatoma cells.

Hepatocyte growth factor down-regulates the alpha-fetoprotein gene expression in PLC/PRF/5 human hepatoma cells

Hepatocyte growth factor (HGF) is a potent mitogen for hepatocytes; however, in certain human hepatoma cell lines, the growth is inhibited by HGF. In the present study, the effect of HGF on the alpha-fetoprotein (AFP) gene expression was analyzed in PLC/PRF/5 human hepatoma cells. HGF did not inhibit cell proliferation, but dose-dependently suppressed AFP secretion at the concentrations of 10 ng/ml or less. By Northern blot analysis, the levels of AFP mRNA were suppressed by HGF, whereas the levels of beta-actin mRNA used as a control did not show any significant changes. In the transient chloramphenicol acetyltransferase plasmid transfection assays, the AFP promoter activity was repressed by HGF, in contrast, the AFP enhancer activity was not affected by HGF. These results suggest that the AFP gene expression is down-regulated by HGF through the suppression of its promoter activity in human hepatoma cells.

Inhibitory effect of prostaglandin Δ12-PGJ2 on cell proliferation and α-fetoprotein expression in HuH-7 human hepatoma cells

9-deoxy-delta 9,delta 12-13,14-dihydro-prostaglandin D2 (delta 12-PGJ2) is a potent inhibitor of proliferation of tumor cells. In the present study, the effect of delta 12-PGJ2 on the alpha-fetoprotein(AFP) and the albumin gene expression was analyzed in HuH-7 human hepatoma cells. delta 12-PGJ2 inhibited the cell growth and reduced the medium AFP concentrations dose-dependently. To determine whether this decline of AFP depends only on the relative decrease in cell numbers by delta 12-PGJ2, or is in part, due to the decrease in the cellular AFP synthesis by delta 12-PGJ2, Northern blot analysis was performed in this study. By Northern blotting, it was shown that delta 12-PGJ2 caused a marked reduction in the levels of the AFP mRNA and the albumin mRNA. In contrast, the level of the beta-actin mRNA was not changed by delta 12-PGJ2. In the transient chloramphnicol acetyltransferase plasmid transfection experiments, delta 12-PGJ2 did not suppress the AFP enhancer activity, which possibly regulates both the AFP and the albumin gene expression in HuH-7 hepatoma cells, but resulted in the selective repression of the AFP and the albumin promoter activity. These results suggest that delta 12-PGJ2 suppresses not only cell growth but also expression of the AFP gene and the albumin gene at the transcriptional level in human hepatoma cells.