Cytoplasmic alpha-fetoprotein functions as a co-repressor in RA-RAR signaling to promote the growth of human hepatoma Bel 7402 cells. Cancer Lett. 2009;285:190-199. [PMID: 19501957 DOI: 10.1016/j.canlet.2009.05.014]

A comprehensive analysis of the oncogenic and prognostic role of TBC1Ds in human hepatocellular carcinoma

Backgrounds

TBC1D family members (TBC1Ds) are a group of proteins that contain the Tre2-Bub2-Cdc16 (TBC) domain. Recent studies have shown that TBC1Ds are involved in tumor growth, but no analysis has been done of expression patterns and prognostic values of TBC1Ds in hepatocellular carcinoma (HCC).

Methods

The expression levels of TBC1Ds were evaluated in HCC using the TIMER, UALCN and Protein Atlas databases. The correlation between the mRNA levels of TBC1Ds and the prognosis of patients with HCC in the GEPIA database was then analyzed. An enrichment analysis then revealed genes that potentially interact with TBC1Ds. The correlation between levels of TBC1Ds and tumor-infiltrating immune cells (TIICs) in HCC were studied using the TIMER 2.0 database. Finally, a series of in vitro assays verified the role of TBC1Ds in HCC progression.

Results

This study revealed the upregulated expression of TBC1Ds in HCC and the strong positive correlation between the mRNA levels of TBC1Ds and poor prognosis of patients with HCC. The functions of TBC1Ds were mainly related to autophagy and the AMPK pathway. There was also a significant correlation between level of TBC1Ds and tumor-infiltrating immune cells (TIICs) in HCC. The promoting role of TBC1Ds in HCC progression was verified in vitro assays.

Conclusion

The results of this analysis indicate that TBC1Ds may serve as new biomarkers for early diagnosis and treatment of HCC.

Role of Alpha-Fetoprotein in the Pathogenesis of Cancer

Alpha-fetoprotein (AFP) belongs to the albuminoid protein family and is considered as the fetal analog of serum albumin. This plasma protein is initially synthesized in the fetal liver and yolk sac and shows a maximum peak near the end of the first trimester. Later, concentrations begin to decline prenatally and drop precipitously after birth. This protein has three key ligand-binding pockets for interactions with various biomolecules. It contains multiple phosphorylation and acetylation sites for the regulation of physiological and pathophysiological states. High serum AFP titer is an established biomarker for yolk sac, embryonal and hepatocellular carcinoma. The present review critically analyzes the chemical nature, receptors, clinical implications, and therapeutic aspects of AFP, underpinning the development of different types of cancer.

An Insight Into the Role of Alpha-Fetoprotein (AFP) in the Development and Progression of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the primary malignancy of hepatocytes and the second most common cause of cancer-related mortality across the globe. Despite significant advancements in screening, diagnosis, and treatment modalities for HCC, the mortality-to-incidence ratio remain unacceptably high. A recent study indicates that a minor population of HCCs are AFP negative or express the normal range of AFP levels. Although it is a gold standard and a more reliable biomarker in the advanced stage of HCC and poorly differentiated tumors, it does not serve as a suitable means for screening HCC. AFP plays a significant role in the development and progression of HCC and understanding its role is crucial. By examining the molecular mechanisms involved in AFP-mediated tumorigenesis, we can better understand HCC pathogenesis and identify potential therapeutic targets. This article details the role of alpha-fetoprotein (AFP) in the carcinogenic transformation of hepatocytes. The article also focuses on information about the structure, biosynthesis, and regulation of AFP at the gene level. Additionally, it discusses the immune evasion, metastasis, and control of gene expression that AFP mediates during HCC.

AFP deletion leads to anti-tumorigenic but pro-metastatic roles in liver cancers with concomitant CTNNB1 mutations

HCC remains one of the most prevalent and deadliest cancers. Serum AFP level is a biomarker for clinical diagnosis of HCC, instead the contribution of AFP to HCC development is clearly highly complex. Here, we discussed the effect of AFP deletion in the tumorigenesis and progression of HCC. AFP deletion in HepG2 cells inhibited the cell proliferation by inactivating PI3K/AKT signaling. Surprisingly, AFP KO HepG2 cells appeared the increasing metastatic capacity and EMT phenotype, which was attributed to the activation of WNT5A/β-catenin signal. Further studies revealed that the activating mutations of CTNNB1 was closely related with the unconventional pro-metastatic roles of AFP deletion. Consistently, the results of DEN/CCl4-induced HCC mouse model also suggested that AFP knockout suppressed the growth of HCC primary tumors, but promoted lung metastasis. Despite the discordant effect of AFP deletion in HCC progression, a drug candidate named OA showed the potent suppression of HCC tumor growth by interrupting AFP-PTEN interaction and, importantly, reduced the lung metastasis of HCC via angiogenesis suppression. Thus, this study demonstrates an unconventional effect of AFP in HCC progression, and suggests a potent candidate strategy for HCC therapy.

Prognostic significance of combined α-fetoprotein and CA19-9 for hepatocellular carcinoma after hepatectomy

Background

The prognosis of hepatocellular carcinoma (HCC) varies considerably among patients with the same disease stage and characteristics, and only about two thirds show high levels of α-fetoprotein (AFP), a common prognostic indicator for HCC. Here, we assessed whether the combination of presurgical serum levels of AFP and carbohydrate antigen 19-9 (CA19-9) can predict the prognosis of HCC patients after hepatectomy.

Methods

The clinicopathological characteristics and post-hepatectomy outcomes of 711 HCC patients were retrospectively reviewed. The patients were classified into three groups based on whether their preoperative serum levels of both AFP and CA19-9 were higher than the respective cut-offs of 400 ng/ml and 37 U/ml [double positive (DP)], the level of only one marker was higher than the cut-off [single positive (SP)], or neither level was higher than the cut-off [negative (N)]. The overall survival (OS) and recurrence-free survival (RFS) rates were estimated using Kaplan–Meier curves. Univariate and multivariate survival analyses were performed to identify the clinicopathological factors significantly associated with HCC prognosis.

Results

The 1-year, 3-year, and 5-year RFS and OS rates in the N group were significantly higher than those in the SP group, while the DP group showed the lowest rates. Multivariate Cox regression analysis showed that large tumor size (> 5 cm), multiple tumors (≥ 2), incomplete tumor capsule, positive microvascular invasion, Barcelona Clinic Liver Cancer C stage, and CA19-9 level > 37 U/mL were independent risk factors for RFS and OS in HCC patients. Moreover, aspartate aminotransferase levels > 40 U/L proved to be an independent prognostic factor for OS.

Conclusion

The combination of serum AFP and CA19-9 levels may be a useful prognostic marker for HCC patients after hepatectomy.

Vincosamide Has a Function for Inhibiting Malignant Behaviors of Hepatocellular Carcinoma Cells

BACKGROUND

Vincosamide (Vinco) was first identified in the methanolic extract of the leaves of Psychotria leiocarpa, and Vinco has important anti-inflammatory effects and activity against cholinesterase, Vinco also has a trait to anti-tumor. However, whether Vinco can inhibit the malignant behaviors of hepatocellular carcinoma (HCC) cells is still unclear. In the present study, we explored the role of Vinco in suppressing the malignant behaviors of HCC cells.

METHODS

MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl-tetrazolium bromide), trypan blue exclusion assay, the Cell Counting Kit (CCK)-8 and flow cytometric analysis were applied to detect the proliferation and apoptosis of HCC cells; electron microscopy was performed to observe the change of cellular mitochondrial morphology; scratch repair and Transwell assays were used to analyze the migration and invasion of HCC cells; expression and localization of proteins were detected by laser confocal microscopy and Western blotting; the growth of the cancer cells in vivo was assessed in a mouse tumorous model.

RESULTS

At a dose of 10 - 80 µg/mL, Vinco inhibited the proliferation, migration, invasion and promoted apoptosis of HCC cells in a dose-dependent manner but had low cytotoxicity effect on normal liver cells. Additionally, 80 µg/mL of Vinco could significantly disrupt the morphology of mitochondria, suppress the migration and invasion of HCC cells. The growth of HCC cells in the animal tumorous model was significantly inhibited after treatment with Vinco (10 mg/kg/day) for 3 days. The results of the present study indicated that Vinco (10 - 80 µg/mL) played a role in activating caspase-3, promoting the expression of phosphate and tension homology deleted on chromosome 10 (PTEN), and inhibiting the phosphorylation of AKT (Ser473) and mTOR (Thr2448); Vinco also has a trait for suppressing the expression of CXCR4, Src, MMP9, EpCAM, Ras, Oct4 and cancer stem cell "stemness markers" CD133 and CD44 in HCC cells.

CONCLUSIONS

Vinco has a role in inhibiting the malignant behaviors of HCC cells; the role molecular mechanism of Vinco may be involved in restraining expression of the growth-, metastasis-related factors, such as Src, Ras, MMP9, EpCAM, CXCR4; activating the activity of caspase-3 and blocking PI3K/AKT signaling pathway. Thus, Vinco should be considered as a new chemotherapy agent for HCC patients.

Retinoids in the Pathogenesis and Treatment of Liver Diseases

Vitamin A (VA), all-trans-retinol (ROL), and its analogs are collectively called retinoids. Acting through the retinoic acid receptors RARα, RARβ, and RARγ, all-trans-retinoic acid, an active metabolite of VA, is a potent regulator of numerous biological pathways, including embryonic and somatic cellular differentiation, immune functions, and energy metabolism. The liver is the primary organ for retinoid storage and metabolism in humans. For reasons that remain incompletely understood, a body of evidence shows that reductions in liver retinoids, aberrant retinoid metabolism, and reductions in RAR signaling are implicated in numerous diseases of the liver, including hepatocellular carcinoma, non-alcohol-associated fatty liver diseases, and alcohol-associated liver diseases. Conversely, restoration of retinoid signaling, pharmacological treatments with natural and synthetic retinoids, and newer agonists for specific RARs show promising benefits for treatment of a number of these liver diseases. Here we provide a comprehensive review of the literature demonstrating a role for retinoids in limiting the pathogenesis of these diseases and in the treatment of liver diseases.

GP73-mediated secretion of AFP and GP73 promotes proliferation and metastasis of hepatocellular carcinoma cells

Golgi protein 73 (GP73) and alpha fetoprotein (AFP) serve as biomarkers for the diagnosis of hepatocellular carcinoma (HCC), and their serum levels correlate with patients’ outcomes. However, the mechanisms underlying these correlations are unknown. Here we show that GP73 increased the secretion of AFP through direct binding to AFP, thereby promoting the proliferation and metastasis of HCC cells that expressed AFP and its receptor (AFPR). Extracellular GP73 contributed to the proliferation and metastasis of HCC cells independent of AFP and AFPR. Moreover, extracellular AFP and GP73 synergized to enhance the malignant phenotype of HCC cells. Furthermore, extracellular GP73 and AFP inhibited the antitumor effects of sorafenib and synergistically increased the drug resistance of HCC cells. These findings, which reveal the mechanism of GP73-mediated secretion of AFP and its effects on the malignant phenotype of HCC cells, provide a comprehensive theoretical basis for the diagnosis and treatment of HCC and identify potential drug targets.

Role of Alpha-Fetoprotein in Hepatocellular Carcinoma Drug Resistance

Hepatocellular carcinoma (HCC) is a major type of primary liver cancer and a major cause of cancer-related deaths worldwide because of its high recurrence rate and poor prognosis. Surgical resection is currently the major treatment measure for patients in the early and middle stages of the disease. Because due to late diagnosis, most patients already miss the opportunity for surgery upon disease confirmation, conservative chemotherapy (drug treatment) remains an important method of comprehensive treatment for patients with middle- and late-stage liver cancer. However, multidrug resistance (MDR) in patients with HCC severely reduces the treatment effect and is an important obstacle to chemotherapeutic success. Alpha-fetoprotein (AFP) is an important biomarker for the diagnosis of HCC. The serum expression levels of AFP in many patients with HCC are increased, and a persistently increased AFP level is a risk factor for HCC progression. Many studies have indicated that AFP functions as an immune suppressor, and AFP can promote malignant transformation during HCC development and might be involved in the process of MDR in patients with liver cancer. This review describes drug resistance mechanisms during HCC drug treatment and reviews the relationship between the mechanism of AFP in HCC development and progression and HCC drug resistance.

AFP-Inhibiting Fragments for Drug Delivery: The Promise and Challenges of Targeting Therapeutics to Cancers

Alpha fetoprotein (AFP) plays a key role in stimulating the growth, metastasis and drug resistance of hepatocellular carcinoma (HCC). AFP is an important target molecule in the treatment of HCC. The application of AFP-derived peptides, AFP fragments and recombinant AFP (AFP-inhibiting fragments, AIFs) to inhibit the binding of AFP to intracellular proteins or its receptors is the basis of a new strategy for the treatment of HCC and other cancers. In addition, AIFs can be combined with drugs and delivery agents to target treatments to cancer. AIFs conjugated to anticancer drugs not only destroy cancer cells with these drugs but also activate immune cells to kill cancer cells. Furthermore, AIF delivery of drugs relieves immunosuppression and enhances chemotherapy effects. The synergism of immunotherapy and targeted chemotherapy is expected to play an important role in enhancing the treatment effect of patients with cancer. AIF delivery of drugs will be an available strategy for the targeted treatment of cancer in the future.

HBP1-mediated transcriptional repression of AFP inhibits hepatoma progression

Background

Hepatoma is a common malignancy of the liver. The abnormal high expression of alpha-fetoprotein (AFP) is intimately associated with hepatoma progress, but the mechanism of transcriptional regulation and singularly activation of AFP gene in hepatoma is not clear.

Methods

The expression of transcription factor HBP1 and AFP and clinical significance were further analyzed in hepatoma tissues from the patients who received surgery or TACE and then monitored for relapse for up 10 years. HBP1-mediated transcriptional regulation of AFP was analyzed by Western blotting, Luciferase assay, Realtime-PCR, ChIP and EMSA. After verified the axis of HBP-AFP, its impact on hepatoma was measured by MTT, Transwell and FACS in hepatoma cells and by tumorigenesis in HBP1^−/− mice.

Results

The relative expressions of HBP1 and AFP correlated with survival and prognosis in hepatoma patients. HBP1 repressed the expression of AFP gene by directly binding to the AFP gene promoter. Hepatitis B Virus (HBV)-encoded protein HBx promoted malignancy in hepatoma cells through binding to HBP1 directly. Icaritin, an active ingredient of Chinese herb epimedium, inhibited malignancy in hepatoma cells through enhancing HBP1 transrepression of AFP. The repression of AFP by HBP1 attenuated AFP effect on PTEN, MMP9 and caspase-3, thus inhibited proliferation and migration, and induced apoptosis in hepatoma cells. The deregulation of AFP by HBP1 contributed to hepatoma progression in mice.

Conclusions

Our data clarify the mechanism of HBP1 in inhibiting the expression of AFP and its suppression in malignancy of hepatoma cells, providing a more comprehensive theoretical basis and potential solutions for the diagnosis and treatment of hepatoma.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01881-2.

Alpha-Fetoprotein Binding Mucin and Scavenger Receptors: An Available Bio-Target for Treating Cancer

Alpha-fetoprotein (AFP) entrance into cancer cells is mediated by AFP receptors (AFPRs) and exerts malignant effects. Therefore, understanding the structure of AFPRs will facilitate the development of rational approaches for vaccine design, drug delivery, antagonizing immune suppression and diagnostic imaging to treat cancer effectively. Throughout the last three decades, the identification of universal receptors for AFP has failed due to their complex carbohydrate polymer structures. Here, we focused on the two types of binding proteins or receptors that may serve as AFPRs, namely, the A) mucin receptors family, and B) the scavenger family. We presented an informative review with detailed descriptions of the signal transduction, cross-talk, and interplay of various transcription factors which highlight the downstream events following AFP binding to mucin or scavenger receptors. We mainly explored the underlying mechanisms involved mucin or scavenger receptors that interact with AFP, provide more evidence to support these receptors as tumor AFPRs, and establish a theoretical basis for targeting therapy of cancer.

Hepatocellular carcinoma and multiple myeloma with elevated globulin: a case report and literature review

A 60-year-old male patient presented with a serum α-fetoprotein (AFP) level of 2940.5 ng/mL accompanied by a significant increase in serum globulin. Hepatitis B virus (HBV) DNA was 2.85 × 10³ (normal value <1.0 × 10³). B-mode ultrasound and magnetic resonance imaging showed characteristic manifestations and he was clinically diagnosed with hepatocellular carcinoma in January 2015. He received radiofrequency ablation and tenofovir disoproxil anti-HBV therapy and his serum AFP and globulin levels were significantly reduced. In March 2018, he presented at our Hematology Department with fatigue and a pale complexion. At that time, his serum AFP level was normal, with hemoglobin 61 g/L and globulin 64.7 g/L. He was diagnosed with multiple myeloma (MM) by bone marrow examination, and immunofixation electrophoresis. The patient received PCD chemotherapy (bortezomib 2.0 g/dL on days 1, 4, 8, and 11 plus cyclophosphamide 0.3 g/dL on days 1-4 plus dexamethasone 20 mg/dL on days 1-2, 4-5, 8-9, and 11-12). The patient finally died of MM complicated by disseminated intravascular coagulation.

URRENT CONCEPT OF THE STRUCTURAL AND FUNCTIONAL PROPERTIES OF ALFA-FETOPROTEIN AND THE POSSIBILITIES OF ITS CLINICAL APPLICATION

This paper was aimed to review the literature data from native and foreign sources accumulated for 40-years period of research of the features of the molecular structure, functions, production and application of human alpha-fetoprotein (AFP), which is known as one of the most studied and increasingly demanded proteins. Results of fundamental studies performed with the use of modern methods, including various types of electrophoresis, chromatography, electron microscopy and immunoassay, in order to characterize the principal physicochemical capacities and localization of free and bound forms of AFP, as well as polypeptide structure, heterogeneity and topography of AFP receptors are highlighted here. The data on the mechanisms of AFP synthesis, its conformational features, binding sites and intracellular metabolism are also presented. The concepts of physiological functions and mechanisms of AFP transport in an organism are presented. Data on AFP isolation from the natural primary products and its production by means of recombinant and synthetic methods are shown. This review also summarizes information on the current possibilities of clinical application of AFP and the prospects for its usage in anticancer therapy for targeted delivery of chemotherapy drugs, with emphasis on the description of the recent progress in this field.

Intracellular alpha-fetoprotein interferes with all-trans retinoic acid induced ATG7 expression and autophagy in hepatocellular carcinoma cells

Retinoic acid and retinoid acid receptor (RA-RAR) signaling exhibits suppressive functions in the progression of hepatocellular carcinoma (HCC) through multiple mechanisms. However, whether RA-RAR signaling induces autophagy that contributes its anti-tumor activity in HCC remains elusive. In the current study, the effects of RA-RAR pathway on autophagy were investigated in two HCC cell lines: alpha-fetoprotein (AFP) positive PLC/PRF/5 and AFP negative HLE cells. Cell autophagy was analyzed with western blot for detection of LC3 conversion and p62/SQSTM1 degradation while autophagy flux was assayed using the mRFP-GFP-LC3 reporter. Cell apoptosis and viability were analyzed by caspase-3 activity, TdT-mediated dUTP nick end labeling (TUNEL) assay, and Cell Counting Kit (CCK)-8, respectively. Chromatin immunoprecipitation (ChIP) was employed to detect the binding of RAR onto the promoter of autophagy-relevant 7 (ATG7), and co-immunoprecipitation (CoIP) was used to analyze the interaction of AFP and RAR. The results showed that ATRA dosage and time-dependently induced high levels of cell autophagy in both the PLC/PRF/5 and HLE cells, which was accompanied with up-regulation of ATG7. ChIP assay showed that RAR was able to bind to its responsive elements on ATG7 promoter. Impairment of ATG7 induction or blockade of autophagy with chloroquine aggravated ATRA induced apoptosis of HCC cells. Furthermore, intracellular AFP was able to complex with RAR in PLC/PRF/5 cells. Knockdown of AFP in PLC/PRF/5 cells augmented the up-regulation of ATG7 by ATRA while overexpression of AFP in HLE cells attenuated ATRA induced ATG7 expression and autophagy. Thus, ATRA induced ATG7 and autophagy participated in its cytotoxicity on HCC cells and AFP interfere with the induction of ATG7 and autophagy through forming complex with RAR.

Overexpression of GATA5 Stimulates Paclitaxel to Inhibit Malignant Behaviors of Hepatocellular Carcinoma Cells

Objective

Explore the effect of GATA5 expression on Paclitaxel inhibiting growth of hepatocellular carcinoma (HCC) cells.

Materials and Methods

In the experimental study, HCC cell lines (HLE, Bel7402 and PLC/PRF/5) were treated with different concentrations of Paclitaxel (5-20 mg/ml) for 24 hours. HLE cells were transfected with GATA5-siRNA vector, while Bel7402 and PLC/PRF/5 cells were transfected with overexpressed GATA5 vector for 24 hours, followed by treatment of the cells with Paclitaxel (10 mg/ml) for 24 hours and subsequently 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay to detect growth of HCC cells. Soft agar cultured was used to analyze formation of colony. Apoptosis of HCC cells were detected by Flow cytometer. Migration of HCC cells was observed by trawell assays. Western blotting and laser confocal microscopy were utilized to detect expression and location of the proteins.

Results

Inhibiting expression of GATA5 reduced sensitivity of HLE cells to Paclitaxel, while overexpression of GATA5 increased sensitivity of Bel7402 cells and PLC/PRF/5 cells to Paclitaxel. Overexpression of GATA5 played a role in stimulating Paclitaxel to inhibit growth, colony formation and migration, as well as enhance apoptosis in HCC cells. Overexpression of GATA5 also promoted Paclitaxel to inhibit expression of reprogramming genes, such as Nanog, EpCAM, c-Myc and Sox2 in Bel7402 and PLC/PRF/5 cells. Inhibited expression of GATA5 led to enhancement of the expression of CD44 and CD133, in HLE cells. Overexpression of GATA5 was not only alone but also synergized with Paclitaxel to inhibit expression of CD44 and CD133 in Bel7402 or PLC/PRF/5 cells.

Conclusion

Overexpression of GATA5 played a role in enhancing Paclitaxel to inhibit the malignant behaviors of HCC cells. It was involved in suppressing expression of the reprogramming genes and stemness markers. Targeting GATA5 is an available strategy for applying paclitaxel to therapy of patients with HCC.

Translocatome: a novel resource for the analysis of protein translocation between cellular organelles

Here we present Translocatome, the first dedicated database of human translocating proteins (URL: http://translocatome.linkgroup.hu). The core of the Translocatome database is the manually curated data set of 213 human translocating proteins listing the source of their experimental validation, several details of their translocation mechanism, their local compartmentalized interactome, as well as their involvement in signalling pathways and disease development. In addition, using the well-established and widely used gradient boosting machine learning tool, XGBoost, Translocatome provides translocation probability values for 13 066 human proteins identifying 1133 and 3268 high- and low-confidence translocating proteins, respectively. The database has user-friendly search options with a UniProt autocomplete quick search and advanced search for proteins filtered by their localization, UniProt identifiers, translocation likelihood or data complexity. Download options of search results, manually curated and predicted translocating protein sets are available on its website. The update of the database is helped by its manual curation framework and connection to the previously published ComPPI compartmentalized protein–protein interaction database (http://comppi.linkgroup.hu). As shown by the application examples of merlin (NF2) and tumor protein 63 (TP63) Translocatome allows a better comprehension of protein translocation as a systems biology phenomenon and can be used as a discovery-tool in the protein translocation field.

Acetylation of alpha-fetoprotein promotes hepatocellular carcinoma progression

Alpha-fetoprotein (AFP) is a well-established biomarker for hepatocellular carcinoma (HCC). Here, we investigated the acetylation state of AFP in vivo. AFP acetylation was regulated by the acetyltransferase CBP and the deacetylase SIRT1. Acetylation of AFP at lysines 194, 211, and 242 increased the stability of AFP protein by decreasing its ubiquitination and proteasomal degradation. AFP acetylation promoted its oncogenic role by blocking binding to the phosphatase PTEN and the pro-apoptotic protein caspase-3, which increased signaling for proliferation, migration, and invasion and decreased apoptosis. High levels of acetylated AFP in HCC tissues were associated with HBV infection and correlated with poor prognosis and decreased patient survival. In HCC cells, hepatitis B virus X protein (HBx) and palmitic acid (PA) increased the level of acetylated AFP by disrupting SIRT1-mediated deacetylation. AFP acetylation plays an important role in HCC progression and provides a new potential prognostic marker and therapeutic target for HCC.

GATA5 inhibits hepatocellular carcinoma cells malignant behaviours by blocking expression of reprogramming genes

Evidence indicated that GATA5 may suppress hepatocellular carcinoma (HCC) cell malignant transformation, but the mechanism of how GATA5 affects cancer cell reprogramming to inhibit HCC malignant behaviour is still unclear. In this study, we report that the expression of β‐catenin and reprogramming genes p‐Oct4, Nanog, Klf4, c‐myc and EpCAM was significantly higher in HCC tissues compared to normal liver tissues. In contrast, the expression of GATA5 was significantly lower in HCC tissues compared to normal liver tissues. Transfection of CDH‐GATA5 vectors into HCC cells (HLE, Bel 7402 and PLC/PRF/5 cells) increased the GATA5 expression and decreased the expression of β‐catenin and reprogramming genes p‐Oct4, Nanog, Klf4, c‐myc and EpCAM. Increased GATA5 expression by transfection with its expression vectors was also able to inhibit the cell growth, colony formation and capability of migration, invasion, while promoting apoptosis in HCC cells. Results revealed that GATA5 co‐localization with β‐catenin in the cytoplasm, preventing β‐catenin from entering the nucleus. Treatment with the specific Wnt/β‐catenin pathway inhibitor salinomycin was able to reduce the expression of β‐catenin and reprogramming genes. Salinomycin exerted a similar influence as GATA5, and siRNA‐GATA5 restored β‐catenin and reprogramming gene expression. This study demonstrates that an increase in the expression of GATA5 inhibits the expression of β‐catenin and reprogramming genes and suppresses tumour growth, colony formation, metastasis and invasion, while promoting apoptosis in HCC cells. The mechanism of GATA5 inhibiting the malignant behaviours of HCC cells may involve in the disruption of the Wnt/β‐catenin pathway and the reduction of reprogramming gene expression.

Efficacy and tolerability of AFPep, a cyclic peptide with anti-breast cancer properties

PURPOSE

The purpose of this study is to assess the efficacy and safety profile of AFPep, a 9-amino acid cyclic peptide prior to its entry into pre-clinical toxicology analyses en route to clinical trials.

METHODS

AFPep was assessed for anti-estrogenic activity in a mouse uterine growth assay and for breast cancer therapeutic efficacy in a human tumor xenograft model in mice. AFPep was assessed for tolerability in a variety of in vivo models, notably including assessment for effects on rat liver and human hepatocellular carcinoma cell lines and xenografts.

RESULTS

AFPep arrests the growth of human MCF-7 breast cancer xenografts, inhibits the estrogen-induced growth of mouse uteri, and does not affect liver growth nor stimulate growth of human hepatocellular carcinoma cell lines when growing in vitro or as xenografts in vivo. AFPep is well tolerated in mice, rats, dogs, and primates.

CONCLUSIONS

AFPep is effective for the treatment of ER-positive breast cancer and exhibits a therapeutic index that is substantially wider than that for drugs currently in clinical use. The data emphasize the importance of pursuing pre-clinical toxicology studies with the intent to enter clinical trials.

Alpha fetoprotein antagonises benzyl isothiocyanate inhibition of the malignant behaviors of hepatocellular carcinoma cells

Benzyl isothiocyanate (BITC) is a dietary isothiocyanate derived from cruciferous vegetables. Recent studies showed that BITC inhibited the growth of many cancer cells, including hepatocellular carcinoma (HCC) cells. Alpha-fetoprotein (AFP) is a important molecule for promoting progression of HCC, in the present investigation, we explore the influence of AFP on the role of BITC in the malignant behaviours of HCC cells, and the potential underlying mechanisms. We found thatBITC inhibited viability, migration, invasion and induced apoptosis of human liver cancer cell lines, Bel 7402(AFP producer) and HLE(non-AFP producer) cells in vitro. The role of BITC involve in promoting actived-caspase-3 and PARP-1 expression, and enhancing caspase-3 activity but decreasing MMP-2/9, survivin and CXCR4 expression. AFP antagonized the effect of BITC. This study suggests that BITC induced significant reductions in the viability of HCC cell lines. BITC may activate caspase-3 signal and inhibit the expression of growth- and metastasis-related proteins; AFP is an pivotal molecule for the HCC chemo-resistance of BITC.

Icaritin inhibits the expression of alpha-fetoprotein in hepatitis B virus-infected hepatoma cell lines through post-transcriptional regulation

Although it has showed that icaritin can apparently suppress growth of HCC by reducing the level of AFP, the intrinsic mechanism remains unclear. In this study, we explored the possible mechanism of miRNAs on post-transcriptional regulation of AFP gene, as well as the effects of HBV infection and icaritin in hepatoma cells. The results showed that miR-620, miR-1236 and miR-1270 could bind target sites in the range of 9–18 nt and 131–151 nt downstream of the stop codon in the AFP mRNA 3′-UTR to suppress the expression of AFP. Mutation of these target sites could reverse the effects of these miRNAs. Icaritin (10 μM) might reduce the stability and translational activity of AFP mRNA by increasing the expression levels of these mentioned miRNAs. HBV infection resulted in apparent decreases of these miRNAs and, consequently, increased AFP expression. The results indicated that miR-620, miR-1236 and miR-1270 are critical factors in the post-transcriptional regulation of AFP. Icaritin can counteract the effect of HBV. These findings will contribute to full understanding of the regulatory mechanism of AFP expression in hepatoma cells. And also it revealed a synergistic mechanism of HBV infection and elevation of AFP in the pathogenesis of HCC, as well as the potential clinical significance of icaritin on the therapy of HCC induced by HBV.

Structural basis for alpha fetoprotein-mediated inhibition of caspase-3 activity in hepatocellular carcinoma cells

Alpha-fetoprotein (AFP) is an early serum growth factor in the foetal liver development and hepatic carcinogenesis; However, the precise biological role of cytoplasmic AFP remains elusive. Although we recently demonstrated that cytoplasmic AFP might interact with caspase-3 and inhibit the signal transduction of apoptosis in human hepatocellular carcinoma (HCC) cells, the details of this interaction are not clear. To reveal the molecular relationship between AFP and caspase-3, we performed molecular docking, co-immunoprecipitation (Co-IP), laser confocal microscopy, site-directed mutagenesis and functional experiments to analyse the key amino acid residues in the binding site of caspase-3. The results of Co-IP, laser confocal microscopy and functional analyses were consistent with the computational model. We also used the model to explain why AFP cannot bind to caspase-8. These results provide the molecular basis for the AFP-mediated inhibition of caspase-3 activity in HCC cells. Altogether, we found that AFP interacts with caspase-3 through precise amino acids, namely loop-4 residues Glu-248, Asp-253 and His-257. The results further demonstrated that AFP plays a critical role in the inhibition of the apoptotic signal transduction that mediated by caspase-3. Thus, AFP might represent a novel biotarget for the therapy of HCC patients.

Purification and characterization of a bioactive alpha-fetoprotein produced by HEK-293 cells

Alpha-fetoprotein (AFP) is a biomarker that is used to diagnose hepatocellular carcinoma (HCC) and can promote malignancy in HCC. AFP is an important target in the treatment of liver cancer. To obtain enough AFP to screen for AFP inhibitors, we expressed and purified AFP in HEK-293 cells. In the present study, we produced AFP in the cells and harvested highly pure rAFP (or recombinant expression AFP in HEK-293 cells). We also analysed the bioactivity of rAFP and found that rAFP promoted growth of the human HCC cells, antagonize paclitaxel inhibition of HCC cell proliferation, suppress expression of active caspase-3, and promote expression of Ras and survivin. This study provides a method to produce significant amounts of AFP for use in biochemical assays and functional studies and to screen AFP inhibitors for use in HCC therapy.

Expression and bioactivity of human α-fetoprotein in a Bac-to-Bac system

α-fetoprotein (AFP) is an early serum growth factor in foetal embryonic development and hepatic oncogenesis. A growing number of investigations of AFP as a tumour-specific biomarker have concluded that AFP is an important target for cancer treatment. AFP also plays an immunomodulatory role in the treatment of several autoimmune diseases, such as rheumatoid arthritis, multiple sclerosis, myasthenia gravis and thyroiditis. In an effort to support biochemical screening and drug design and discovery, we attempted to express and purify human AFP in a Bac-to-Bac system. Two key factors affecting the expression of recombinant human AFP (R-AFP), namely the infectious baculovirus inoculum volume and the culturing time post-infection, were optimized to maximize the yield. We achieved a high yield of approximately 1.5 mg/l of harvested medium with a 72–96 h incubation period after infection and an inoculum volume ratio of 1:100. We also assessed the role of R-AFP in the proliferation of the human liver cancer cell line Bel 7402, and the results indicated that R-AFP promoted the growth of hepatoma cells. We concluded that this method can produce high yields of R-AFP, which can be used for studies related to AFP.

Benzyl-isothiocyanate Induces Apoptosis and Inhibits Migration and Invasion of Hepatocellular Carcinoma Cells in vitro

Despite consideration of benzyl isothiocyanate(BITC) is applied to prevention and therapeutic of cancer, the role of BITC in inducing apoptosis, and inhibiting migration and invasion of hepatocellular carcinoma(HCC) cells is still unclear. In this study, we aim to explore the effects of BITC on the growth, migration and invasion of HCC cells in vitro. When human HCC cell lines, Bel 7402 and HLE, were treated with an optimal concentration of BITC for 48 hours, the results indicated that BITC inhibits growth and promotes apoptosis of HCC cells; BITC has a significant inhibitory effect on the migration and invasion of HCC cells. BITC stimulated expression of caspase-3/8 and PARP-1, and suppressed expression of survivin, MMP2/9 and CXCR4. BITC also inhibited the enzymatic activities of MMP2 and MMP9. Altogether, BITC was able to induce apoptosis and suppress the invasive and migratory abilities of Bel 7402 and HLE cells. The role mechanism of BITC might involve an up-regulating the expression of apoptosis-related proteins and down-regulating the expression of metastasis-related proteins. BITC may be applied as a novel chemotherapy for HCC patients.

Alpha-foetoprotein (AFP): A multi-purpose marker in hepatocellular carcinoma

Alpha-foetoprotein (AFP), one of the first protein tumour markers discovered, is widely used today in clinical practice. Its application for the screening and diagnosis of hepatocellular carcinoma (HCC), the most frequent form of primary liver tumour, is a matter of extensive debate. In addition to the studies focused on the role of the AFP in the diagnosis of HCC, in recent years AFP has been used to guide the therapeutic choice in HCC and monitor the treatment. Here, we summarize the latest studies that show the interest of AFP quantification in determining the suitability of liver transplantation or to follow-up on patients receiving the targeted treatment sorafenib. We also highlight the recent studies showing the active role of AFP in tumour progression, and the new modes of regulation of this tumour marker. Among these is the regulation of AFP through tumour proteostasis and the Unfolded Protein Response (UPR). We discuss the implications of this new knowledge in the therapeutic context, in terms of interpreting serum levels of AFP, and the new perspectives offered by AFP for the study of tumour proteostasis.

Umbilical cord-derived mesenchymal stem cells inhibit growth and promote apoptosis of HepG2 cells

Hepatocellular carcinoma is the fifth most common type of cancer worldwide and remains difficult to treat. The aim of this study was to investigate the effects of mesenchymal stem cells (MSCs) derived from the umbilical cord (UC‑MSCs) on HepG2 hepatocellular carcinoma cells. UC‑MSCs were co‑cultured with HepG2 cells and biomarkers of UC‑MSCs were analyzed by flow cytometry. mRNA and protein expression of genes were determined by reverse transcription‑polymerase chain reaction and flow cytometry, respectively. Passage three and seven UC‑MSCs expressed CD29, CD44, CD90 and CD105, whereas CD34 and CD45 were absent on these cells. Co‑culture with UC‑MSCs inhibited proliferation and promoted apoptosis of HepG2 cells in a time‑dependent manner. The initial seeding density of UC‑MSCs also influenced the proliferation and apoptosis of HepG2 cells, with an increased number of UC‑MSCs causing enhanced proliferation inhibition and cell apoptosis. Co‑culture with UC‑MSCs downregulated mRNA and protein expression of α‑fetoprotein (AFP), Bcl‑2 and Survivin in HepG2 cells. Thus, UC‑MSCs may inhibit growth and promote apoptosis of HepG2 cells through downregulation of AFP, Bcl‑2 and Survivin. US-MSCs may be used as a novel therapy for treating hepatocellular carcinoma in the future.

Alpha fetoprotein antagonizes apoptosis induced by paclitaxel in hepatoma cells in vitro

Hepatocellular carcinoma (HCC) cell resistance to the effects of paclitaxel has not been adequately addressed. In this study, we found that paclitaxel significantly inhibited the viability of HLE, Bel 7402 and L-02 cells in a dose- and time-dependent manner. HLE cells and L-02 cells resisted the cytotoxicity of paclitaxel when transfected with pcDNA3.1-afp vectors. However, Bel 7402 cell sensitivity to paclitaxel was increased when transfected with alpha fetoprotein (AFP)-siRNA. Bel 7402 cell resistance to paclitaxel was associated with the expression of the “stemness” markers CD44 and CD133. Paclitaxel significantly inhibited growth and promoted apoptosis in HLE cells and L-02 cells by inducing fragmentation of caspase-3 and inhibiting the expression of Ras and Survivin, but pcDNA3.1-afp vectors prevented these effects. However, paclitaxel could not significantly promote the cleavage of caspase-3 or suppress the expression of Ras and Survivin in Bel 7402 cells. Silenced expression of AFP may be synergistic with paclitaxel to restrain proliferation and induce apoptosis, enhance cleavage of caspase-3, and suppress the expression of Ras and Survivin. Taken together, AFP may be an important molecule acting against paclitaxel-inhibited proliferation and induced apoptosis in HCC cells via repressing the activity of caspase-3 and stimulating the expression of Ras and Survivin. Targeted inhibition of AFP expression after treatment with paclitaxel is an available strategy for the therapy of patients with HCC.

Hepatitis B Virus X Protein Driven Alpha Fetoprotein Expression to Promote Malignant Behaviors of Normal Liver Cells and Hepatoma Cells

Background: The infection of Hepatitis B virus (HBV) is closely associated with the development of hepatocellular carcinoma(HCC), HBV-X protein(HBx) is able to induce expression of alpha-fetoprotein(AFP) in normal liver cells, and AFP harbors a function to promote malignant transformation of normal liver cells, but the role AFP playing in malignant behaviors of HCC cells is still unclear.

Methods: Fifty-six liver tissue samples were collected from the clinical patients through hepatectomy(include normal liver tissues, HBV-related hepatitis liver tissues and HBV-related HCC tissues), and diagnosis of these tissues by pathology section, expression of AFP, Ras and CXCR4 were evidenced by immunohisochemical staining and Western blotting; The proliferation of human normal liver cells line L-02 cells and human hepatoma cells line, HLE cells(non AFP-producing) were performed by MTT method; Repaired capacity of L-02 and HLE cells were compared by wound healing assay; Migration and invasion of these cells were analyzed by Transwell chamber assay; HBx expressed vectors(pcDNA3.1-HBx) were constructed and transfected into L-02 and HLE cells, effects of pcDNA3.1-HBx on the malignant behaviors were also detected by MTT, Transwell chamber assay and the expression of AFP, Ras and CXCR4 were evidenced by Western blotting.

Results: we found that expression of AFP, Ras and CXCR4 in HBV-related HCC and lymph nodes metastasis tissues were significantly elevated compared with HBV-related HCC, non metastasis tissues and HBV-related hepatitis tissues; Expression of AFP, Ras and CXCR4 in HBV-related hepatitis tissues were significantly enhanced compared with normal liver tissues; The growth ratio, migratory and invasive ability, expression of AFP, Ras and CXCR4 of the cells were outstanding promoted while L-02 and HLE cells were transfected with pcDNA3.1-HBx vectors. The proliferation ratio, migration and invasion ability, and expression of Ras and CXCR4 were significantly inhibited while L-02-X and HLE-X cells(stably transfected with pcDNA3.1-HBx) were silenced AFP expression by AFP-siRNA.

Conclusions: HBx through stimulating expression of AFP to promote malignant behaviors of human normal liver cells and HCC cells; AFP maybe used as a novel biotarget for therapeutics of HCC patients.

Hepatitis B virus X protein induces expression of alpha-fetoprotein and activates PI3K/mTOR signaling pathway in liver cells

The hepatitis B virus (HBV)-X protein (HBx) induces malignant transformation of liver cells, and elevated expression of alpha-fetoprotein (AFP) is a significant biomarker of hepatocarcinogenesis. However, the role of AFP in HBV-related hepatocarcinogenesis is unclear. In this study, we investigated the regulatory impact of AFP expression on HBx-mediated malignant transformation of human hepatocytes. We found that HBV induced the expression of AFP before that of oncogenes, e.g., Src, Ras and chemokine (C-X-C motif) receptor 4 (CXCR4), and AFP activated protein kinase B (AKT) and mammalian target of rapamycin (mTOR) in HBV-related HCC tissues and in human liver cells transfected with HBx. Cytoplasmic AFP interacted with and inhibited phosphatase and tensin homolog deleted on chromosome 10 (PTEN), activating the phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway and promoting mTOR-mediated stimulation of the transcription factor hypoxia inducible factor-1α (HIF-1α), and therefore led to the activation of the promoters of Src, CXCR4, and Ras genes. On the contrary, reduced expression of AFP by siRNA resulted in the repression of p-mTOR, pAKT, Src, CXCR4, and Ras in human malignant liver cells. Taken together, for the first time our study indicates that HBx-induced AFP expression critically promote malignant transformation in liver cells through the activation of PI3K/mTOR signaling.

Alpha fetoprotein plays a critical role in promoting metastasis of hepatocellular carcinoma cells

A high level of serum alpha fetoprotein (AFP) is positively associated with human hepatocellular carcinoma (HCC) carcinogenesis and metastasis; however, the function of AFP in HCC metastasis is unknown. This study has explored the effects of AFP on regulating metastatic and invasive capacity of human HCC cells. Forty-seven clinical patients' liver samples were collected and diagnosed; HCC cells line, Bel 7402 cells (AFP-producing) and liver cancer cell line cells (non-AFP-producing) were selected to analyse the role of AFP in the metastasis of HCC cells. The results indicated that high serum concentration of AFP was positively correlated with HCC intrahepatic, lymph nodes and lung metastasis. Repressed expression of AFP significantly inhibited the capability of migration and invasion of Bel 7402 cells, expression of keratin 19 (K19), epithelial cell adhesion molecule (EpCAM), matrix metalloproteinase 2/9 (MMP2/9) and CXC chemokine receptor 4 (CXCR4) were also down-regulated in Bel 7402 cells; migration and invasion, expression of K19, EpCAM, MMP2/9 and CXCR4 were significantly enhanced when HLE cells were transfected with AFP-expressed vector. The results demonstrated that AFP plays a critical role in promoting metastasis of HCC; AFP promoted HCC cell invasion and metastasis via up-regulating expression of metastasis-related proteins. Thus, AFP may be used as a novel therapeutic target for treating HCC patients.

Role of alpha-fetoprotein in hepatitis B virus-induced hepatocellular carcinoma: Prospect in clinical application

Mammalian alpha-fetoprotein (AFP) as a fetal specific alpha-globulin that has been used as a serum fetal defect/tumor marker for diagnosis and prediction of liver disease. Over the past decade, research indicates that AFP as an intracellular signal molecule is not only a biomarker but also interacts with hepatitis B virus (HBV) and hepatitis B virus protein x and plays multifarious roles in the development of hepatocellular carcinoma, especially in HBV-induced liver cancer.

Molecular Analysis of AFP and HSA Interactions with PTEN Protein

Human cytoplasmic alpha-fetoprotein (AFP) has been classified as a member of the albuminoid gene family. The protein sequence of AFP has significant homology to that of human serum albumin (HSA), but its biological characteristics are vastly different from HSA. The AFP functions as a regulator in the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) pathway, but HSA plays a key role as a transport protein. To probe their molecular mechanisms, we have applied colocalization, coimmunoprecipitation (co-IP), and molecular docking approaches to analyze the differences between AFP and HSA. The data from colocalization and co-IP displayed a strong interaction between AFP and PTEN (phosphatase and tensin homolog), demonstrating that AFP did bind to PTEN, but HSA did not. The molecular docking study further showed that the AFP domains I and III could contact with PTEN. In silicon substitutions of AFP binding site residues at position 490M/K and 105L/R corresponding to residues K490 and R105 in HSA resulted in steric clashes with PTEN residues R150 and K46, respectively. These steric clashes may explain the reason why HSA cannot bind to PTEN. Ultimately, the experimental results and the molecular modeling data from the interactions of AFP and HSA with PTEN will help us to identify targets for designing drugs and vaccines against human hepatocellular carcinoma.

HBx induced AFP receptor expressed to activate PI3K/AKT signal to promote expression of Src in liver cells and hepatoma cells

BACKGROUND

Hepatitis B virus (HBV)-X protein(HBx) is a transactivator of host several cellular genes including alpha-fetoprotein(AFP) and AFP receptor(AFPR) which contributes to HBV-associated tumor development. The expression of AFP/AFPR are correlated with hepatocellular carcinoma(HCC)-initial cells. But the role of AFP and AFPR in promoting occurrence of HBV-related HCC were still unclear.

METHODS

A total of 71 clinical patients' liver specimens, normal human liver cells L-02 and HCC cell lines, PLC/PRF/5 were selected for analyzing the effects of HBx on expression of AFP, AFPR and Src. The expression of goal proteins were detected by Immunohistochemical stained and Western blotting; HBx-expressed vectors were constructed and transfected into L-02 cells, laser confocal microscopy was applied to observe expression and location of AFP, AFPR and Src in the normal liver cells and HCC cells, soft agar colony formation assay was used to observe colonies formed of the cells.

RESULTS

We confirmed HBx gives preference to promote the expression of AFP and AFPR; HBx priors to up-regulate the expression of AFPR and AFP in L-02 cells and in normal liver specimens; AFPR signal been able to stimulate Src expression. The results also indicated that phosphatidylinositol 3-kinase(PI3K) inhibitors Ly294002 and GDC0941 effectively suppress AFPR mediated up-regulation expression of Src in AFPR positive HCC lines.

CONCLUSIONS

HBx priors to drive the expression of AFP and AFPR to promote expression of Src in normal liver cells and hepatoma cells; AFP and AFPR maybe play pivotal role in HBV-related hepatocarcinogenesis; Targeting AFPR is an available therapeutic strategy of HCC.

Alpha fetoprotein mediates HBx induced carcinogenesis in the hepatocyte cytoplasm

Although tumor-associated fetal protein AFP has demonstrated utility as a clinical tumor marker, the significance of intracellular AFP is still unclear. The aim of this study was to explore the role of cytoplasmic AFP during HBx induced carcinogenesis, which had not previously been recognized; 614 HCC patients were analyzed for correlation of HBV infection with AFP level, and much higher AFP levels were found in HBsAg positive patients. Tumor tissue specimens from 20 HCC patients were used for analysis of AFP and GADD45α. Analysis of HCC specimens showed that upregulation of cytoplasmic AFP is associated with down-regulation of GADD45α in neoplastic tissue. Transfected HBx promotes transcription of AFP by acting on the elements in the AFP gene regulatory region. HBx itself did not directly impact transcription of GADD45α. However, the obstruction of RAR signaling by HBx induced elevation of AFP, which led to down-regulation of GADD45α. Cytoplasmic AFP was able to interact with RAR, disrupting its entrance into the nucleus and binding to the elements in the regulatory region of the GADD45α gene. Knockdown of AFP in siRNA-transfected AFP positive cell lines was synchronously associated with an incremental increase of RAR binding to DNA, as well as upregulation of GADD45α and it was contrary in AFP gene-transfected AFP negative cell lines. These results indicate cytoplasmic AFP is not only a histochemical tumor biomarker for human hepatoma but is also an intracellular signal molecule and potential participant in HBx induced hepatocarcinogenesis.

HBx induced expression of alpha fetoprotein drives malignant transformation of liver cells

The development of hepatocellular carcinoma (HCC) is closely related to hepatitis B virus (HBV) infection, and HBV-X protein (HBx) plays a critical role in the malignant transformation of liver cells. HBx stimulates the expression of alpha fetoprotein (AFP) via restraining the transcription activity of P53 in the early stage of HCC genesis. Recently, studies have indicated that HBx preferentially promotes AFP expression during the malignant transformation of hepatic cells, and AFP accelerates the expression of malignant behavior related molecules through activating the phosphatidylinositol-3 kinase (PI3K)/protein kinas A (AKT) signaling pathway. These results suggest that AFP may be an important factor for HBx driven hepatocarcinogenesis. The discovery of novel function of AFP implicates that AFP can be used not only as a tumor marker for HBV-related HCC but also as a target for HCC therapy.

Alpha-fetoprotein activates AKT/mTOR signaling to promote CXCR4 expression and migration of hepatoma cells

CXCR4, stromal cell-derived factor-1α(SDF 1α) receptor, stimulates growth and metastasis of hepatocellular carcinoma (HCC). Alpha-fetoprotein(AFP) governs the expression of some metastasis-related genes. Here we report that AFP and CXCR4 levels correlated in HCC tissues. AFP-expressing vectors induced CXCR4. In agreement, AFP depletion by siRNA decreased CXCR4. AFP co-localized and interacted with PTEN, thus inducing CXCR4 by activating AKT(Ser473) phosphorylation. In turn, phospho-mTOR(Ser2448) entered the nucleus and bound the CXCR4 gene promoter. Thus, AFP promoted migration of HCC cells. In concusion, AFP induced CXCR4 by activating the AKT/mTOR signal pathway.

Alpha fetoprotein can induce malignant transformation of liver cells and be used as a therapeutic target for hepatocellular carcinoma

Alpha-fetoprotein (AFP) is associated with the development of hepatocellular carcinoma (HCC) and widely used as a golden tumor marker for diagnosing HCC since the AFP gene is activated in the early stage of malignant transformation of liver cells. However, the molecular mechanisms responsible for the role of AFP in hepatocarcinogenesis remain poorly understood. Recently, we found that hepatitis B virus (HBV) preferentially induces the expression of AFP when triggering malignant transformation of hepatocytes, and AFP activates phosphoinositide-3-kinase (PI3K)/protein kinase B (AKT) signaling by inhibiting the activity of phosphatase and tensin homolog deleted on chromosome ten (PTEN). Our results also indicated that AFP not only impedes all-trans retinoid acid receptor-β (RAR-β) regulated expression of target genes, but also blocks the transduction of apoptotic signaling by suppressing the activity of Caspase3. Inhibited expression of AFP is able to augment HCC sensitivity to tumor necrosis factor-related apoptosis-induced ligand (TRAIL) and all-trans retinoid acid. These data indicate that AFP can drive the malignant transformation of liver cells and antagonize apoptosis induced by agents for HCC. Taken together, these findings suggest that AFP may drive the malignant transformation of liver cells and can be used as a target for therapy of HCC.

Saikosaponin-d affects the differentiation, maturation and function of monocyte-derived dendritic cells

Saikosaponin-d (Ssd) is a triterpenoid saponin derived from Bupleurum falcatum L., which has been shown to exhibit a variety of pharmacological properties, including anti-inflammatory, antibacterial and antiviral properties. The aim of the present study was to investigate the effect of Ssd on the differentiation, maturation and function of human monocyte-derived dendritic cells (DCs) isolated from condylomata acuminata patients. The results of the present study demonstrated that Ssd reduced the differentiation of DCs, as evidenced by decreased expression levels of cluster of differentiation (CD)1a, CD80 and CD86 molecules and increased CD14 expression. Expression levels of the mannose receptor and CD32 were also significantly elevated, which was associated with enhanced fluorescein isothiocyanate-dextran endocytic activity. Furthermore, Ssd treatment promoted DC maturation by increasing the expression levels of CD40, CD83, CD80 and CD86. In addition, the function of mature DCs, including the secretion of IL-12 and the stimulation of lymphocyte proliferation, was significantly increased following Ssd administration. In conclusion, the present study indicated that Ssd exhibited immunomodulatory effects and may be a novel potent chemopreventive drug candidate for the treatment of condylomata acuminata.

Alpha-fetoprotein: a renaissance

Alpha-fetoprotein (AFP) is a major mammalian embryo-specific and tumor-associated protein that is also present in small quantities in adults at normal conditions. Discovery of the phenomenon of AFP biosynthesis in carcinogenesis by G. Abelev and Yu. Tatarinov 50 years ago, in 1963, provoked intensive studies of this protein. AFPs of some mammalian species were isolated, purified and physico-chemically and immunochemically characterized. Despite the significant success in study of AFP, its three-dimensional structure, mechanisms of receptor binding along with a structure of the receptor itself and, what is the most important, its biological role in embryo- and carcinogenesis remain still obscure. Due to difficulties linked with methodological limitations, research of AFP was to some extent extinguished by the 1990 s. However, over the last decade a growing number of investigations of AFP and its usage as a tumor-specific biomarker have been observed. This was caused by the use of new technologies, primarily, computer-based and genetic engineering approaches in studying of this very important oncodevelopmental protein. Our review summarizes efforts of different scientific groups throughout the world in studying AFP for 50 years with emphasis on detailed description of recent achievements in this field.

Review of the adenocarcinoma cell surface receptor for human alpha-fetoprotein; proposed identification of a widespread mucin as the tumor cell receptor

The identification of a tumor cell receptor for alpha-fetoprotein (AFP) has long been sought in the field of medicine. The uptake and endocytosis of AFP by rat tumor cells in 1983 sparked a series of confirmatory reports which were extended to include multiple tumor types in rats, mice, and humans. The following year, French investigators characterized the binding properties of the AFP receptor but they did not purify and characterize the receptor. It was not until 1991-1992 that an AFP receptor was partially purified and characterized from both human monocytes and breast cancer cells. By 1993, monoclonal antibodies had been raised against the "AFP receptor" derived from breast cancer extracts with claims that the receptor was a widespread oncoprotein biomarker for cancer. To date, that receptor has yet to be identified due to its complex multimeric structure and carbohydrate composition. The present report will review the literature of the multiple AFP receptors previously including their cellular uptake, transmembrane passage, and partial biochemical characterization. . In addition, evidence derived from computer modeling, proteolytic/fragmentation cleavage patterns, domain structure analysis, and protein binding software analysis will be presented in a proposed identification of a widespread protein/gene family of transmembrane proteins which fits many, if not most, of the criteria attributed to the AFP receptor. The proposed receptor protein family is tentatively identified as an epithelial cell surface mucin constituting one (or more) of many classes of single-pass transmembrane proteins. Present data do not support the concept that the AFP receptor is a "universal" tumor receptor and/or biomarker, but rather a widespread mucin protein that functions primarily in protecting and lubricating epithelial mucosal layers, and engaging in signal transduction; the mucin only binds AFP as a molecule serving in a subordinate or ancillary function.

Expression of AFP and STAT3 is involved in arsenic trioxide-induced apoptosis and inhibition of proliferation in AFP-producing gastric cancer cells

Alpha-fetoprotein (AFP)-producing gastric cancer (AFPGC), represented by the production of AFP, has a more aggressive behavior than common gastric cancer. The underlying mechanisms are not well understood. Arsenic trioxide (As₂O₃) is used clinically to treat acute promyelocytic leukemia(APL) and has activity in vitro against several solid tumor cell lines, with induction of apoptosis and inhibition of proliferation the prime effects. Signal transducer and activator of transcription 3 (STAT3) has an important role in tumorigenesis of various primary cancers and cancer cell by upregulating cell-survival and downregulating tumor suppressor proteins. Here, we found decreased expression of AFP and STAT3 after induction of apoptosis by As₂O₃ in the AFPGC FU97 cells. Also, the level of the STAT3 target oncogene Bcl-2 was decreased with As₂O₃, and that of the tumor suppressor Bax was increased. Furthermore, STAT3 expression and depth of invasion and lymph node metastasis were associated. Survival of patients with gastric cancer was lower with AFP and STAT3 double overexpression than with overexpression of either alone. Downregulation of AFP and STAT3 expression plays an important role in As₂O₃-induced apoptosis of AFPGC cells, which suggests a new mechanism of As₂O₃-induced cell apoptosis. As₂O₃ may be a possible agent for AFPGC treatment.

Alpha-fetoprotein receptor as an early indicator of HBx-driven hepatocarcinogenesis and its applications in tracing cancer cell metastasis

AFP and its receptor (AFPR) are early indicators of HBx-driven hepatocarcinogenesis. Clinical specimens, normal human liver cells L-02 and HCC cell lines were selected for analyzing the effects of HBx on expression of AFP, AFPR, Src, CXCR4, and Ras. Results showed that AFPR localized in the membranes of HCC samples. HBx upregulated the expression of AFPR and AFP prior to expression of Src, CXCR4, and Ras in L-02 cells and in liver specimens; Target-labeled AFPR was able to reveal the location and metastatic status of HCC in vivo. In this way, actuated expression of AFPR served as an indicator suitable for use in the early diagnosis of HBx-driven malignant transformation of hepatocytes. Labeled AFPR may be applied to trace primary and metastatic HCC.

Relationship of α-fetoprotein levels and development of hepatocellular carcinoma in hepatitis C patients with liver cirrhosis

α-fetoprotein (AFP) is a tumor marker of hepatocellular carcinoma (HCC) and has also been reported to reflect the effectiveness of long-term low-dose interferon (IFN) therapy in hepatitis C virus (HCV)-infected patients with chronic liver disease. The correlation between AFP levels and the incidence of HCC has been discussed over a long period. We investigated whether high levels of AFP at the time of diagnosis were associated with an increased incidence of HCC in patients with HCV. A total of 107 HCV patients with liver cirrhosis without other risks were evaluated for the predictive value of non-invasive risk factors for HCC, including age, gender, alcohol intake, aspartate and alanine aminotransferase levels, bilirubin, albumin, platelet count and AFP levels at study entry, as well as the IFN therapy received. During the follow-up period, HCC developed in 68 (63.6%) patients. Kaplan-Meier estimates were made to assess the cumulative risk of HCC. The 10-year cumulative incidence rate of HCC was 80%. Cox regression analysis was performed on several variables, including age, gender, alcohol consumption, experience of IFN therapy and biochemical parameters. The following factors were identified as exhibiting an increased risk of HCC by univariate analysis: aspartate transaminase (AST) ≥71 IU/l, alanine transaminase (ALT) ≥60 IU/l, AFP ≥6 ng/ml and IFN therapy. Multivariate analysis identified that the AFP level [6–19 ng/ml: hazard ratio (HR), 2.22; P=0.006 and ≥20 ng/ml: HR, 2.09; P=0.003] was an independent and significant risk factor for the development of HCC. A slightly elevated (6–19 ng/ml) AFP level may be a risk factor for HCC in certain cases. By contrast, AFP levels <6 ng/ml indicate a low risk of HCC development in HCV patients with liver cirrhosis.

Alpha-fetoprotein acts as a novel signal molecule and mediates transcription of Fn14 in human hepatocellular carcinoma

BACKGROUND & AIMS

The function of cytoplasmic AFP as a regulatory factor in the growth of tumor cells has been well defined. However, its precise mechanism of action and its clinical significance remain to be worked out.

METHODS

Specimens from HCC patients were analyzed by using immunohistochemistry, co-immunoprecipitation (CoIP), and chromatin immunoprecipitation (ChIP) assays to evaluate the role of AFP in RAR signaling-mediated carcinogenesis. Quantitative real-time reverse transcription PCR, Western blotting, confocal microscopy, CoIP, GST pull-down, siRNA, gene transfection, and ChIP assays were also used for analysis of cell lines.

RESULTS

RAR is able to interact with cytoplasmic AFP and binds to the element of the regulatory region of the Fn14 gene in the neoplastic tissue of HCC patients. An assay of hepatocyte cell lines of differing AFP expression showed that cytoplasmic AFP is able to block ATRA-induced nuclear translocation of RAR and expression of the Fn14 gene. Knockdown of AFP in siRNA-transfected HepG2 and Bel7402 cells led to greater binding of RAR to its response element. The expression of the Fn14 gene was therefore up regulated as reflected by increases in mRNA and protein levels. Conversely, transfection of HLE and L02 cells (AFP negative) with the afp gene resulted in apparent reduction of RAR binding to DNA and Fn14 protein.

CONCLUSIONS

Demonstration of the involvement of cytoplasmic AFP in RAR-mediated expression of the Fn14 gene strongly indicates AFP plays a signal molecule-like role in the regulation of hepatocellular carcinoma growth.