Effects of alpha fetoprotein on escape of Bel 7402 cells from attack of lymphocytes

Alpha-fetoprotein: Past, present, and future

Alpha-fetoprotein (AFP) is a glycoprotein that plays an important role in immune regulation with critical involvement in early human development and maintaining the immune balance during pregnancy. Postfetal development, the regulatory mechanisms controlling AFP undergo a shift and AFP gene transcription is suppressed. Instead, these enhancers refocus their activity to maintain albumin gene transcription throughout adulthood. During the postnatal period, AFP expression can increase in the setting of hepatocyte injury, regeneration, and malignant transformation. It is the first oncoprotein discovered and is routinely used as part of a screening strategy for HCC. AFP has been shown to be a powerful prognostic biomarker, and multiple HCC prognosis models confirmed the independent prognostic utility of AFP. AFP is also a useful predictive biomarker for monitoring the treatment response of HCC. In addition to its role as a biomarker, AFP plays important roles in immune modulation to promote tumorigenesis and thus has been investigated as a therapeutic target in HCC. In this review article, we aim to provide an overview of AFP, encompassing the discovery, biological role, and utility as an HCC biomarker in combination with other biomarkers and how it impacts clinical practice and future direction.

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.

Glucose metabolism reprogramming promotes immune escape of hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is a complex process that plays an important role in its progression. Abnormal glucose metabolism in HCC cells can meet the nutrients required for the occurrence and development of liver cancer, better adapt to changes in the surrounding microenvironment, and escape the attack of the immune system on the tumor. There is a close relationship between reprogramming of glucose metabolism and immune escape. This article reviews the current status and progress of glucose metabolism reprogramming in promoting immune escape in liver cancer, aiming to provide new strategies for clinical immunotherapy of liver cancer.

Research Progress in Alpha-Fetoprotein-Induced Immunosuppression of Liver Cancer

Abstract:

Liver cancer is one of the most common malignant tumors, with limited treatment and 8.2% high mortality. Liver cancer is the fourth leading cause of cancer-related deaths, which seriously endangers human life and health. Approximately 70% of liver cancer patients show increased serum alpha-fetoprotein (AFP) levels. AFP is the main diagnostic and prognostic indicator of liver cancer. AFP, a key marker of liver cancer, plays a crucial role in regulating the proliferation of tumor cells, apoptosis, and induction of cellular immune escape. High levels of AFP during embryonic development protect the embryos from maternal immune attack. AFP also promotes immune escape of liver cancer cells by inhibiting tumor-infiltrating lymphocytes (TILs), natural killer cells (NK), dendritic cells (DC), and macrophages; thus, it is also used as a target antigen in immunotherapy for liver cancer. AFP is highly expressed in liver cancer cells. In addition to being used in the diagnosis of liver cancer, it has become a target of immunotherapy for liver cancer as a tumor-associated antigen. In immunotherapy, it was also confirmed that early AFP response was positively correlated with the efficacy of immunotherapy. Early AFP responders had longer PFS and OS than non-responders. At present, the methods of immunotherapy for liver cancer mainly include Adoptive Cell Transfer Therapy (ACT), tumor vaccine therapy, immune checkpoint inhibitors (ICIs) therapy and so on. A large number of studies have shown that AFP mainly plays a role in ACT and liver cancer vaccines. This review presents the research progress of AFP and immunosuppression of liver cancer.

The Emerging Influences of Alpha-Fetoprotein in the Tumorigenesis and Progression of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the sixth most common cancer worldwide, and its mortality rate is the third-highest, after lung cancer and colorectal cancer. Currently, systematic targeted therapies for HCC mainly include multiple kinase inhibitors and immunotherapy. However, these drugs carry a black-box warning about the potential for inducing severe toxicity, and they do not significantly prolong the survival period of patients due to the highly heterogeneous characteristics of HCC etiology. In order to improve the prediction, effective treatment and prognosis of HCC, the tools and different biomarkers in clinical practices are recommended. Alpha-fetoprotein (AFP) is the earliest and the most widely used serum marker in the detection of HCC. Interestingly, serum AFP and cytoplasmic AFP show different, even opposite, roles in the cancer progression of HCC. This review focuses on biological characteristics, regulatory mechanisms for gene expression, emerging influences of AFP in HCC and its possible implications in HCC-targeted therapy.

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.

Genetic correction of serum AFP level improves risk prediction of primary hepatocellular carcinoma in the Dongfeng-Tongji cohort study

Serum alpha-fetoprotein (AFP) is the most commonly used tumor biomarker for screening and diagnosis of primary hepatocellular carcinoma (HCC). However, the predictive effect for HCC risk is still unsatisfactory. The aim of this prospective study was to estimate whether the individual genetic correction could improve the prediction efficiency of AFP for HCC risk. A prospective analysis with 9819 baseline HCC-free individuals based on a large population-based Chinese cohort study was performed. Two single-nucleotide polymorphisms (SNPs) associated with serum AFP level were used to calculate the genetic corrected AFP level (rs12506899 and rs2251844). Statistical analysis including logistic regression analysis and the area under the receiver operating characteristic (ROC) curve were used to assess the discriminative ability of the original and genetic corrected AFP level for HCC risk. The odds ratios (ORs) and 95% confidence intervals (95% CIs) were presented. Fifty-seven participants were diagnosed with HCC for the first time. After adjusting AFP level with genetic effects, the participants for HCC risk increased compared to those with AFP level alone (OR = 5.34, 95% CI = 2.57-11.13; P < 0.001 vs. OR = 5.04, 95% CI = 2.46-10.30; P < 0.001). In addition, the area under the curve (AUC) for the discrimination of HCC elevated from 0.611 to 0.726. The efficiency in HCC prediction using serum AFP level can be improved by adjusting AFP level based on genetic effects. The genetic correction effect on serum AFP should be considered in the clinic application of such tumor biomarkers.

Alpha-Fetoprotein and Hepatocellular Carcinoma Immunity

Hepatocarcinoma is one of the most prevalent gastroenterological cancers in the world with less effective therapy. As an oncofetal antigen and diagnostic marker for liver cancer, alpha-fetoprotein (AFP) possesses a variety of biological functions. Except for its diagnosis in liver cancer, AFP has become a target for liver cancer immunotherapy. Although the immunogenicity of AFP is weak and it could induce the immune escapes through inhibiting the function of dendritic cells, natural killer cells, and T lymphocytes, AFP has attracted more attention in liver cancer immunotherapy. By in vitro modification, the immunogenicity and immune response of AFP could be enhanced. AFP-modified immune cell vaccine or peptide vaccine has displayed the specific antitumor immunity against AFP-positive tumor cells and laid a better foundation for the immunotherapy of liver cancer.

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.

Does alpha-fetoprotein contribute to the mortality and morbidity of human hepatocellular carcinoma? A commentary

The fifth most common cancer worldwide is hepatocellular carcinoma (HCC), while being the third leading cause of global cancer-related deaths. Although HCC incidence is less frequent in North America, it is a common malignancy in Asia and Africa associated with a high rate of mortality and morbidity due to ineffective therapies against cancer growth, invasion, and metastasis. It is well established that serum alpha-fetoprotein (AFP) is the "gold standard" biomarker for liver cancer; however, less known are the biological activities of AFP regarding carcinogenesis, growth, proliferation, and metastasis. Clinicians are well aware that increasing AFP serum levels parallel disease progression of HCC patients, but many are less knowledgeable in the lethal growth-promoting properties of AFP as an autocrine stimulator of hepatoma cell proliferation. This commentary addresses the mortality and morbidity concerning AFP in the genesis, growth, progression, and spread of HCC and emphasizes the perilous consequences of AFP-supported growth in human liver cancer even after liver resection and transplantation. Thus, AFP is not just a biomarker for HCC but also an ardent promoter of liver cancer growth and progression.

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.

Silencing alpha-fetoprotein inhibits VEGF and MMP-2/9 production in human hepatocellular carcinoma cell

Alpha-fetoprotein not only serves as a diagnostic marker for liver cancer, but also posses a variety of biological functions. However, the role of Alpha-fetoprotein on tumor angiogenesis and cell invasion remains incompletely understood. In this study, we aimed to evaluate if Alpha-fetoprotein can regulate the major angiogenic factors and matrix metalloproteinases in human liver cancer cells. Alpha-fetoprotein silencing was achieved by Stealth RNAi. Expression of Alpha-fetoprotein was examined by a full-automatic electrochemistry luminescence immunity analyzer. Expression of VEGF, VEGFR-2, MMP-9, and MMP-2 was examined by Western blot and immunocytochemistry. Apoptosis was detected by TUNEL assay. Angiogenesis was detected by in vitro angiogenesis assay kit. Silencing of Alpha-fetoprotein led to an increased apoptosis, which was associated with a decreased expression of vascular endothelial growth factor, vascular endothelial growth factor receptor 2, matrix metalloproteinases-2/9. These results suggest that Alpha-fetoprotein may play a regulatory role on angiogenesis and cell invasion during liver cancer development.

A genome wide association study of genetic loci that influence tumour biomarkers cancer antigen 19-9, carcinoembryonic antigen and α fetoprotein and their associations with cancer risk

OBJECTIVE

Tumour biomarkers are used as indicators for cancer screening and as predictors for therapeutic responses and prognoses in cancer patients. We aimed to identify genetic loci that influence concentrations of cancer antigen 19-9 (CA19-9), carcinoembryonic antigen (CEA) and α fetoprotein (AFP), and investigated the associations between the significant single nucleotide polymorphisms (SNPs) with risks of oesophageal squamous cell (OSCC), pancreatic and hepatocellular cancers.

DESIGN

We carried out a genome wide association study on plasma CA19-9, CEA and AFP concentrations in 3451 healthy Han Chinese and validated the results in 10 326 individuals. Significant SNPs were further investigated in three case control studies (2031 OSCC cases and 2044 controls; 981 pancreatic cancer cases and 1991 controls; and 348 hepatocellular cancer cases and 359 controls).

RESULTS

The analyses showed association peaks on three genetic loci for CA19-9 (FUT6-FUT3 at 19p13.3, FUT2-CA11 at 19q13.3 and B3GNT3 at 19p13.1; p=1.16×10(-13)-3.30×10(-290)); four for CEA (ABO at 9q34.2, FUT6 at 19p13.3, FUT2 at 19q13.3 and FAM3B at 21q22.3; p=3.33×10(-22)-5.81×10(-209)); and two for AFP (AFP at 4q11-q13 and HISPPD2A at 15q15.3; p=3.27×10(-18) and 1.28×10(-14)). These explained 17.14% of the variations in CA19-9, 8.95% in CEA and 0.57% in AFP concentrations. Significant ABO variants were also associated with risk of OSCC and pancreatic cancers, and AFP variants with risk of hepatocellular cancer (p<0.05).

CONCLUSIONS

This study identified several loci associated with CA19-9, CEA and AFP concentrations. The ABO variants were associated with risk of OSCC and pancreatic cancers and AFP variants with risk of hepatocellular cancer.

Association of alpha fetoprotein levels and presence of parasitical blood vessels with response to TACE in patients with advanced liver cancer

AIM: To assess the value of alpha fetoprotein (AFP) levels and presence of parasitical blood vessels in evaluating response to transarterial chemoembolization (TACE) in patients with advanced liver cancer.

METHODS: One hundred and sixty-three patients who were diagnosed with advanced liver cancer by pathology, iconography and tumor molecular biomarker detection and underwent TACE were included in this study. Serum levels of AFP were detected by radioactive enzyme-linked immunoassay. Computer tomography angiography (CTA) was used to detect parasitical angiogenesis.

RESULTS: Of 131 AFP-positive patients before TACE, 82 had decreased AFP after TACE, and the response rate (survival time over one year) was 87.8% (72/82); 13 had increased AFP, and the response rate was 30.8% (4/13); 36 had unchanged AFP, and the response rate was 58.3% (21/36). In contrast, the response rate was 100% (32/32) in 32 AFP-negative patients. The response rate was significantly higher in AFP-negative patients and patients with decreased AFP than in those with increased or unchanged AFP (P < 0.01). Fifty-six patients developed parasitical blood vessels (including 53 AFP-positive and 3 AFP-negative patients). After TACE, the response rate was significantly higher in patients without parasitical blood vessels than in those having parasitical blood vessels (78.5% vs 41.1%, P < 0.05). The percentage of AFP-positive patients having parasitical blood vessels was significantly higher than that of AFP-negative patients having parasitical blood vessels (40.1% vs 9.4%, P < 0.01).

CONCLUSION: Poor treated effects of mid-advanced stage liver cancer patients cured by TACE due to patients contain High serum levels of AFP and presence of parasitic blood vessels are associated with a poor response to TACE in patients with advanced liver cancer. Measurement of AFP concentration and detection of parasitical angiogenesis by CTA may be used to evaluate the response to TACE therapy in patients with advanced liver cancer.

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.

Risk factors of poor prognosis and portal vein tumor thrombosis after curative resection of solitary hepatocellular carcinoma

BACKGROUND

Predictors of poor prognosis of solitary hepatocellular carcinoma (SHCC), a subgroup encompassing most patients with the malignancy, are still controversial. Hence, risk factors for portal vein tumor thrombosis (PVTT) in SHCC are obscure. The present study was designed to address this issue.

METHOD

Clinicopathological and follow-up data for 156 consecutive patients with SHCC following curative hepatic resection were analyzed using uni- and multi-variate analyses.

RESULTS

Univariate analysis showed that PVTT, tumor-node-metastasis (TNM) stage, Edmondson-Steiner grade and preoperative serum alpha-fetoprotein (AFP) level were associated with the overall and disease-free survival, whereas tumor size only influenced the overall survival. In multivariate Cox regression tests, Edmondson-Steiner grade and TNM stage were independent prognostic markers for both overall and disease-free survival. In addition, the Chi-square test showed that AFP level and Edmondson-Steiner grade were correlated with PVTT. Among them, only Edmondson-Steiner grade was shown to be of independent significance for PVTT in multi-variate logistic regression analysis. Additionally, AFP, the sole preoperative factor for PVTT, was not adequately sensitive and specific.

CONCLUSIONS

Factors relating to post-surgical prognosis and PVTT in SHCC are all tumor-related. Of these, Edmondson-Steiner grade and TNM stage might be of particular importance in survival analysis. In addition, accurate prediction of PVTT by clinicopathological parameters before surgery remains difficult.

Adenoendocrine cell carcinoma of the gallbladder producing a high level of alpha-fetoprotein

We present the case of a 78-year-old Japanese woman with adenoendocrine cell carcinoma of the gallbladder accompanied by a high serum alpha-fetoprotein level. The patient visited our hospital with a complaint of a large mass in the right hypochondrium. Ultrasonography and computed tomography revealed multiple large hepatic tumors, swelling of lymph nodes in the hepatic hilum and para-aortic regions, and a slightly irregular gallbladder wall. The serum alpha-fetoprotein level was 157,428 ng/mL. We initially suspected scirrhous hepatocellular carcinoma, sarcomatous hepatocellular carcinoma, biliary tract cancer, or pancreatic cancer. However, the hepatic tumor biopsy was histologically diagnosed as undifferentiated adenocarcinoma. Immunohistochemical analysis demonstrated that the tumor was positive for cytokeratin 19, focally positive for cytokeratin 7, but negative for hepatocyte paraffin 1 and cytokeratin 20, suggestive of biliary tract carcinoma. Although the patient received a course of hepatic arterial infusion chemotherapy with cisplatin, she died 2 months after admission. Histopathological examination at autopsy revealed that the hepatic tumor was adenoendocrine cell carcinoma of the gallbladder, which was positive for cytokeratin 19, focally positive for cytokeratin 7, chromogranin A, synaptophysin, and weakly positive for alpha-fetoprotein. Labeling index of Ki-67 was 28 %. Interestingly, this was the first case report of adenoendocrine cell carcinoma of the gallbladder that produced a high level of alpha-fetoprotein, which hampered correct diagnosis before autopsy.

Impact of intracellular alpha fetoprotein on retinoic acid receptors-mediated expression of GADD153 in human hepatoma cell lines

The aim of our study was to gain a better understanding of the molecular mechanism underlying the previously unrecognized role of cytoplasmic alpha fetoprotein (AFP) in retinoic acid receptors (RAR) mediated expression and biological effects of GADD153. Using microarray analysis, the expression of the GADD153 gene showed the greatest fold change among apoptosis/growth related genes in response to ATRA. AFP was able to interact with RAR in HepG2 cells, which was undetectable in HLE cells owing to absence of AFP. ATRA promoted nuclei entrance of RAR, expression of GADD153 and apoptosis, and these changes were reversed after transfection with the afp gene or addition of AGN193109. The level of GADD153 was gradually elevated as the effect of AFP was counteracted by increasing dose or prolonging treatment time with ATRA in HepG2 cells. Knockdown of AFP in siRNA-transfected HepG2 cells or over-expression of AFP in afp gene-transfected HLE cells was synchronously associated with up-regulation or down-regulation, respectively, of GADD153 expression. Both ATRA administration and AFP knockdown were each able to promote greater binding of RAR to its response element with consequent elevation of the proportion of apoptotic cells. Conversely, transfection of HLE cells with pcDNA3.1-afp resulted in apparent reduction of RAR binding to DNA and change of biological effect. These data taken together demonstrate the involvement of AFP in RAR-mediated expression and biological effects of GADD153. These findings provide a novel insight into the mechanism underlying the impact of AFP on the RAR signal network.

Elevated serum alpha fetoprotein levels promote pathological progression of hepatocellular carcinoma

AIM: To investigate the biological role of alpha fetoprotein (AFP) and its clinical significance in carcinogenesis of hepatocellular carcinoma (HCC).

METHODS: Clinical analysis of HCC patients and immunohistochemical examination were conducted to evaluate the relationship between serum AFP level and patient mortality. Confocal microscopy, Western blotting, dimethylthiahzolyl-2,5-diphenyl-tetrazolium bromide, Cell Counting Kit-8 assays and flow cytometry were performed to explore the possible mechanism.

RESULTS: Among the 160 HCC patients enrolled in this study, 130 patients survived 2 years (81.25%), with a survival rate of 86.8% in AFP < 2 0 μg/L group, 88.9% in AFP 20-250 μg/L group, and 69.6% in AFP > 250 μg/L group, demonstrating a higher mortality rate in HCC patients with higher AFP levels. Surgical treatment was beneficial only in patients with low AFP levels. The mortality rate of HCC patients with high AFP levels who were treated surgically was apparently higher than those treated with conservative management. The results of immunohistochemistry showed that AFP and AFP receptor were merely expressed in tissues of HCC patients with positive serum AFP. Consistently, in vitro analysis showed that AFP and AFPS were expressed in HepG2 but not in HLE cells. AFP showed a capability to promote cell growth, and this was more apparent in HepG2 cells, in which the proliferation was increased by 3.5 folds. Cell cycle analysis showed that the percentage of HepG2 cells in S phase after exposure to AFP was modestly increased.

CONCLUSION: HCC patients with higher AFP levels show a higher mortality rate, which appears to be attributable to the growth promoting properties of AFP.

Association between pri-miR-218 polymorphism and risk of hepatocellular carcinoma in a Han Chinese population

MicroRNAs are noncoding RNA molecules of 18-25 nucleotides that regulate gene expression at the post-transcriptional level. The aim of this study was to investigate whether pri-miR-218 rs11134527 A/G polymorphism influences the risk of hepatocellular carcinoma (HCC) or not. pri-miR-218 rs11134527 A/G was genotyped in 302 HCC patients and 513 control subjects using the polymerase chain reaction-restriction fragment length polymorphism assay. The AG genotype of pri-miR-218 rs11134527 A/G was associated with family history (p=0.018, odds ratio [OR]=2.96, 95% confidence interval [CI]: 1.16-7.56) and elevated serum α-fetoprotein (serum alpha-fetoprotein [AFP]) levels (≥20 ng/mL; p=0.009, OR=1.92, 95% CI: 1.17-3.14) in HCC patients. These findings suggested that the AG genotype of pri-miR-218 rs11134527 might relate to genetic predisposition and be involved in regulating the expression of AFP in Chinese HCC patients.

Biological functions of alpha-fetoprotein

Alpha-fetoprotein (AFP) is a well-known biomarker for the diagnosis of hepatocellular carcinoma. Extracellular AFP can act as a carrier to transport a variety of ligands or as a growth regulator to control the growth of tumor cells, while intracellular AFP can bind to and interact with transcription factors or some key proteins and function as a signal molecule to regulate cell proliferation or apoptosis. This paper provides novel insights into the mechanisms underlying the role of AFP in carcinogenesis and tumor chemotherapy.

Alpha-fetoprotein: a new member of intracellular signal molecules in regulation of the PI3K/AKT signaling in human hepatoma cell lines

Despite its well-defined role as a serum growth factor during fetal liver development and hepatic oncogenesis, the biological significance of cytoplasmic alpha-fetoprotein (AFP) remains incompletely understood. Here, we provide evidence to illustrate that cytoplasmic AFP may function as a regulator in the phosphatidylinositol 3-kinase (PI3K)/AKT pathway in human hepatocellular carcinoma cells. The results demonstrated colocalization and interaction of AFP and phosphatase and tensin homolog deleted on chromosome 10 (PTEN) in the cytoplasm of AFP-producing Bel 7402 and HepG2 cells, with an interaction distance of 12.6 ± 2.7 Å as determined with the fluorescence resonance energy transfer technique. Knockdown of AFP mRNA or inhibition of AFP expression by all trans-retinoic acid resulted in enhancement of the PTEN level with a synchronous decrease in phosphorylated AKT. Transfection of the afp gene into HLE cells (originally AFP negative) led to a significant activation of AKT signaling. The inhibition of PI3K signaling by LY 294002 was simultaneously reversed by transfection, accompanied by diminution of all trans-retinoic acid-induced upregulation of PTEN and enhancement of cell growth. In conclusion, these results demonstrate that cytoplasmic AFP is involved in regulation of hepatocellular growth and tumorigenesis.

Cytoplasmic alpha-fetoprotein functions as a co-repressor in RA-RAR signaling to promote the growth of human hepatoma Bel 7402 cells

The role of AFP in the retinoic acid-RAR signaling pathway was investigated in human hepatoma Bel 7402 cells. The results showed that AFP and RAR-beta were co-localized and interacted in cytoplasm. AFP may inhibit translocation of RAR-beta into the nucleus via competitive binding to RAR-beta with ATRA, which was reversed by AFP-siRNA transfection. Our data suggest that the ATRA resistance of Bel 7402 cells is at least in part attributable to their high level of cytoplasmic AFP. Thus, by counteracting the effect of AFP, it may be possible to increase the sensitivity of tumor cells to ATRA.

Alpha fetoprotein is a novel protein-binding partner for caspase-3 and blocks the apoptotic signaling pathway in human hepatoma cells

Although there is increasing evidence that alpha fetoprotein (AFP) may function as regulatory factor in the growth of tumor cells, the precise mechanism is still unclear. In the current study, we investigated the role of the cytoplasmic AFP in caspase-3-mediated signaling of apoptosis. Our results showed that low doses of TNF-related apoptosis-inducing ligand (TRAIL) elevated the activity of caspase-8, but not caspase-3. Caspase-3 colocalized and interacted with AFP in the cytoplasm of Bel 7402 cells, and translocated into nuclei in association with the occurrence of apoptosis while cells were under cotreatment with all-trans retinoic acid (ATRA) or TRAIL. AFP was able to form complexes with caspase-3 and block onward transmission of signaling from caspase-8. Knockdown of AFP increased the sensitivity of Bel 7402 cells to TRAIL, and thereby, triggered caspase-3 signaling. No intermolecule interaction occurred between AFP and caspase-8, nor was caspase-8 activity altered after AFP knockdown, demonstrating the selectivity of AFP in interfering with the apoptotic signaling pathway. The effect of AFP on caspase-3 was further confirmed by transfection of the AFP gene into HLE cells (AFP negative). We conclude that ATRA or TRAIL resistance in AFP producing hepatoma is at least, in part, attributable to the high level of the cytoplasmic AFP. Therefore, it is possible that the combination of AFP gene silencing together with ATRA/TRAIL cotreatment will benefit the enhancement of the chemotherapeutic efficiency of these agents on tumors.

Immunotherapy for liver tumors: present status and future prospects

Increasing evidence suggests that immune responses are involved in the control of cancer and that the immune system can be manipulated in different ways to recognize and attack tumors. Progress in immune-based strategies has opened new therapeutic avenues using a number of techniques destined to eliminate malignant cells. In the present review, we overview current knowledge on the importance, successes and difficulties of immunotherapy in liver tumors, including preclinical data available in animal models and information from clinical trials carried out during the lasts years. This review shows that new options for the treatment of advanced liver tumors are urgently needed and that there is a ground for future advances in the field.

Alpha-fetoprotein and other tumour-associated antigens for immunotherapy of hepatocellular cancer

BACKGROUND

Hepatocellular carcinoma (HCC) is a leading cause of cancer death, with few treatment options for advanced disease.

OBJECTIVES

Here, we review the aetiology of HCC and focus on recent data on tumour-associated antigens (TAA) for HCC, their functions and potential use as immunological targets for immune-based therapy for HCC. In addition, we examine some aspects of antigen presentation within the liver.

RESULTS/CONCLUSIONS

alpha-Fetoprotein (AFP) has been investigated for many years as a TAA, and has been tested in recent clinical trials. More recently, additional TAA have been identified and new therapeutic approaches have been investigated which may be testable clinically in this difficult disease setting.

Effect of Bcl-2 and Bax on survival of side population cells from hepatocellular carcinoma cells

AIM

To understand the role and significance of side population (SP) cells from hepatocellular carcinoma (HCC) in hepatocarcinogenesis, development, relapse and metastasis, we simulated the denutrition conditions that cancer cells experience in clinical therapy, observed the different anti-apoptosis ability of SP cells and non-SP cells under such conditions, and established the possible effects of P53, Bcl-2 and Bax on survival of SP cells.

METHODS

We used flow cytometry to analyze and sort the SP and non-SP cells in established HCC lines MHCC97 and hHCC. We evaluated cell proliferation by methyl thiazolyl tetrazolium (MTT) assay and investigated the expression of p53, bcl-2 and bax genes during denutrition, by RT-PCR and immunofluorescence staining.

RESULTS

The percentage of SP cells in the two established HCC lines was 0.25% and 0.5%, respectively. SP cells had greater anti-apoptosis and proliferation ability than non-SP cells. Expression of Bcl-2 and Bax in SP and non-SP cells differed during denutrition. The former was up-regulated in SP cells, and the latter was up-regulated in non-SP cells.

CONCLUSION

It may be that different upstream molecules acted and led to different expression levels of Bcl-2 and Bax in these two cell lines. There was a direct relationship between up-regulation of Bcl-2 and down-regulation of Bax and higher anti-apoptosis ability in SP cells. It may be that the existence and activity of SP cells are partly responsible for some of the clinical phenomena which are seen in HCC, such as relapse or metastasis. Further research on SP cells may have potential applications in the field of anticancer therapy.

Alpha-fetoprotein-specific transfer factors downregulate alpha-fetoprotein expression and specifically induce apoptosis in Bel7402 alpha-fetoprotein-positive hepatocarcinoma cells

AIM

To investigate the mechanisms of AFP-specific transfer factors (AFP-TF) in induced Bel7402 cells apoptosis. Further, we investigate the interaction between AFP-TF and AFP in the apoptosis.

METHODS

Bel7402 and HepG2 AFP-positive hepatocarcinoma cell lines, SK-Hep-1 AFP-negative hepatocarcinoma cell line and Changliver normal liver cell line are used. Cell viability is evaluated by MTT assay and apoptosis is measured by Hoechst33342 staining and TUNEL assay. FACS is used to analyze the cell cycle. AFP expression is examined by RT-PCR, Western blotting and immunocytochemistry. The interaction between AFP-TF and AFP in the apoptosis is investigated by addition of AFP in cultures or AFP transfection in Bel7402 cells prior to AFP-TF treatment. Mitochondrial membrane potential (DeltaPsi(m)) and intracellular Ca2+ concentration are respectively measured by Rhodamine123 and Fluo-3 AM Ester. Western blotting detects the involvement of several apoptosis-related proteins. Finally, caspase-3 and Caspase-9 activity are respectively examined.

RESULTS

AFP-TF can induce apoptosis in Bel7402 and HepG2 AFP-positive hepatocarcinoma cells, but not SK-Hep-1 and Changliver cells. AFP-mRNA level changes little in apoptotic Bel7402 cells; while AFP expression is downregulated and uniformly dispersed throughout the whole cell. Addition of exogenous AFP or overexpression of intracellular AFP can reduce such apoptotic effect. Besides, apoptotic Bel7402 cells show a disruption of DeltaPsi(m), an immediate elevation of Ca2+ concentration, a prominently decreased ratio of bcl-2 to bax, a release of cytochrome c from mitochondria to cytosol, and ultimately an activation of caspase-9 and caspase-3.

CONCLUSION

AFP-TF induced Bel7402 cells apoptosis is mitochondrial-dependent and is mediated by the interaction of AFP-TF with intracellular AFP.

Single nucleotide polymorphism in the promoter region of human alpha-fetoprotein (AFP) gene and its significance in hepatocellular carcinoma (HCC)

BACKGROUND

Variations of serum AFP levels in HCC patients and cell lines are likely due to the differential activity of enhancer/silencer elements that control AFP. To understand the potential mechanism underlying the differential expression of AFP, we have examined the sequence of the AFP promoter in HCC.

METHODS

Direct DNA sequencing was carried out to sequence 980 bp of AFP promoter of DNA samples isolated from 83 HCC patients.

RESULTS

Three novel SNPs in the promoter region of the AFP gene, which have not been previously reported, were found at positions -330, -401 and -692. The level of serum AFP was significantly higher in HCC patients with the CT genotype of 330 SNP or the AG genotype of the 401 SNP. The genotype of CG in 692 SNP was also associated with a significant elevated level of serum AFP, and further this genotype appeared to be associated with the high risk of HCC development. 401 SNP and 692 SNP were located at the positions of known binding sites for transcription factors that have a role in the production of AFP and the growth of tumors.

CONCLUSIONS

The novel polymorphisms identified in the promoter region of the AFP gene may be pathologically significant in HCC.

Comparison of clinical staging systems in predicting survival of hepatocellular carcinoma patients receiving major or minor hepatectomy

AIM

To compare the utility of seven commonly used staging systems in the prediction of survival among patients with hepatocellular carcinoma (HCC) undergoing major or minor hepatectomy.

METHODS

All patients were classified by the Okuda, the TNM, the CLIP, the BCLC, the CUPI, the JIS and the MELD classifications to estimate the probabilities of survival. Survival curves were calculated using the Kaplan-Meier method and were examined using log-rank testing. The overall predictive power for patient survival with each staging system was evaluated using linear trend chi(2) tests and from the area under the receiver operating characteristic (ROC) curve.

RESULTS

In our patient cohort, the log-rank test and the linear trend chi(2) test of the CLIP and JIS systems gave better results than did the other staging systems. The discriminatory ability of the CLIP and JIS staging for death, evaluated by ROC curve areas, was also better. In the subgroups of major hepatectomy patients with a non-cirrhotic liver or minor hepatectomy patients with a cirrhotic liver, the CLIP and JIS systems showed similar better performances in these three tests. The discriminatory ability of the CLIP system was the best in major hepatectomy patients with a non-cirrhotic liver while JIS score discriminated best in minor hepatectomy patients with a cirrhotic liver.

CONCLUSION

Among the seven staging systems, the CLIP and JIS systems perform better than do the others. While the CLIP system should be considered to stage major hepatectomy patients, the JIS system could be chosen to stage minor hepatectomy patients.

alpha-Fetoprotein shields hepatocellular carcinoma cells from apoptosis induced by tumor necrosis factor-related apoptosis-inducing ligand

The interference of alpha-fetoprotein (AFP) with the apoptosis induced by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in Bel 7402 cells was investigated in the current study. The results showed a moderate degree of drug-resistance of Bel 7402 cells to TRAIL. The caspase-3 cascade was the main pathway involved in TRAIL-induced apoptosis, which was virtually abolished in the presence of AFP. TRAIL together with antibody against AFP was able to accelerate the death of tumor cells. This study suggests the possibility a therapeutic strategy for improving clinical treatment of liver tumor with TRAIL could be effected through antagonizing the shelter effect of AFP.

Alpha-fetoprotein antagonizes X-linked inhibitor of apoptosis protein anticaspase activity and disrupts XIAP-caspase interaction

Previous results have shown that the human oncoembryonic protein alpha-fetoprotein (AFP) induces dose-dependent targeting apoptosis in tumor cells, accompanied by cytochrome c release and caspase 3 activation. AFP positively regulates cytochrome c/dATP-mediated apoptosome complex formation in a cell-free system, stimulates release of the active caspases 9 and 3 and displaces cIAP-2 from the apoptosome and from its complex with recombinant caspases 3 and 9 [Semenkova et al. (2003) Eur. J. Biochem. 270, 276-282]. We suggested that AFP might affect the X-linked inhibitor of apoptosis protein (XIAP)-caspase interaction by blocking binding and activating the apoptotic machinery via abrogation of inhibitory signaling. We show here that AFP cancels XIAP-mediated inhibition of endogenous active caspases in cytosolic lysates of tumor cells, as well as XIAP-induced blockage of active recombinant caspase 3 in a reconstituted cell-free system. A direct protein-protein interaction assay showed that AFP physically interacts with XIAP molecule, abolishes XIAP-caspase binding and rescues caspase 3 from inhibition. The data suggest that AFP is directly involved in targeting positive regulation of the apoptotic pathway dysfunction in cancer cells inhibiting the apoptosis protein function inhibitor, leading to triggering of apoptosis machinery.