(2e-4e-6e-10e)-3-7-11-15-tetramethyl-2-4-6-10-14-hexadecapentaenoic-acid and Carcinoma--Hepatocellular

The high rates of hepatocellular carcinoma (HCC) recurrence after initially successful curative therapy emphasize ongoing unmet needs to prevent or reduce HCC recurrence. Retinoid acid (RA), a metabolite of vitamin A and its related analogues (termed retinoids) has been suggested as a promising chemotherapeutic agent in cancer treatment. The synthetic oral retinoid peretinoin is the only agent for the secondary chemoprevention of HCC after curative therapy that is currently well applied into clinical development. Here we present an updated summary of the molecular pathogenesis of HCC and of preclinical and clinical findings with peretinoin, including its clinical characteristics, safety and tolerability profile and future perspectives for clinical use.

Topics: Animals; Antineoplastic Agents; Carcinoma, Hepatocellular; Humans; Liver Neoplasms; Retinoids

Obesity and its related metabolic disorders are serious health problems worldwide, and lead to various health-related complications, including cancer. Among human cancers, hepatocellular carcinoma (HCC) is one of the most common malignancies affected by obesity. Therefore, obesity and its related disorders might be a key target for the prevention of HCC. Recently, new research indicates that the molecular abnormalities associated with obesity, including insulin resistance/hyperinsulinemia, chronic inflammation, adipokine imbalance, and oxidative stress, are possible molecular mechanisms underlying the pathogenesis of obesity-related hepatocarcinogenesis. Green tea catechins and branched-chain amino acids, both of which are classified as nutraceutical agents, have been reported to prevent obesity-related HCC development by improving metabolic abnormalities. The administration of acyclic retinoid, a pharmaceutical agent, reduced the incidence of HCC in obese and diabetic mice, and was also associated with improvements in insulin resistance and chronic inflammation. In this article, we review the detailed molecular mechanisms that link obesity to the development of HCC in obese individuals. We also summarize recent evidence from experimental and clinical studies using either nutraceutical or pharmaceutical agents, and suggest that nutraceutical and pharmaceutical approaches targeting metabolic abnormalities might be a promising strategy to prevent the development of obesity-related HCC.

Topics: Amino Acids, Branched-Chain; Animals; Carcinoma, Hepatocellular; Catechin; Chemoprevention; Diabetes Mellitus, Experimental; Dietary Supplements; Humans; Liver Neoplasms; Mice; Non-alcoholic Fatty Liver Disease; Obesity; Tea; Tretinoin

The current curative treatment modalities for hepatocellular carcinoma (HCC) are unfortunately fraught with high rates of HCC recurrence. Hence there is a need to prevent or reduce HCC recurrence after initial curative therapy. Peretinoin is a synthetic oral retinoid showing significant reduction in the incidence of recurrent or new HCC in patients who had received curative HCC therapy. Areas covered: Peretinoin is analysed against the background of molecular pathogenesis of the different causes of HCC. Publications related to peretinoin since 1996 are reviewed, covering clinical characteristics, safety and tolerance profile as well as the current status of clinical development. Expert commentary: Early phase studies are promising but we need to await the results of the ongoing phase III study of peretinoin in hepatitis C related HCC. Long term impact of peretinoin may be diminished by the foreseeable near eradication of hepatitis C by the direct acting antivirals.

Topics: Animals; Antineoplastic Agents; Carcinoma, Hepatocellular; Chemotherapy, Adjuvant; Clinical Trials as Topic; Hepatitis C; Humans; Liver Neoplasms; Neoplasm Recurrence, Local; Retinoids; Risk Factors; Treatment Outcome

The poor prognosis for patients with hepatocellular carcinoma (HCC) is associated with its high rate of recurrence in the cirrhotic liver. Therefore, more effective strategies need to be urgently developed for the chemoprevention of this malignancy. The malfunction of retinoid X receptor α, a retinoid receptor, due to phosphorylation by Ras/mitogen-activated protein kinase is closely associated with liver carcinogenesis and may be a promising target for HCC chemoprevention. Acyclic retinoid (ACR), a synthetic retinoid, can prevent HCC development by inhibiting retinoid X receptor α phosphorylation and improve the prognosis for this malignancy. Supplementation with branched-chain amino acids (BCAA), which are used to improve protein malnutrition in patients with liver cirrhosis, can also reduce the risk of HCC in obese cirrhotic patients. In experimental studies, both ACR and BCAA exert suppressive effects on HCC development and the growth of HCC cells. In particular, combined treatment with ACR and BCAA cooperatively inhibits the growth of HCC cells. Furthermore, ACR and BCAA inhibit liver tumorigenesis associated with obesity and diabetes, both of which are critical risk factors for HCC development. These findings suggest that pharmaceutical and nutraceutical approaches using ACR and BCAA may be promising strategies for preventing HCC and improving the prognosis of this malignancy.

Topics: Amino Acids, Branched-Chain; Carcinoma, Hepatocellular; Chronic Disease; Clinical Trials as Topic; Dietary Supplements; Humans; Liver Diseases; Liver Neoplasms; Phosphorylation; Retinoid X Receptor alpha; Retinoid X Receptors; Retinoids; Tretinoin

The poor prognosis for hepatocellular carcinoma (HCC) is associated with its high rate of recurrence in the cirrhotic liver. Therefore, development of effective strategies for preventing recurrence and secondary tumors will improve the clinical outcome of HCC patients. A malfunction of the retinoid X receptor-α (RXRα) due to phosphorylation by the Ras-MAPK signaling pathway is profoundly associated with liver carcinogenesis, and thus, may be a promising target for HCC chemoprevention. Acyclic retinoid (ACR), which inhibits Ras-MAPK activation and RXRα phosphorylation, successfully prevents HCC recurrence, thus improving patient survival. The fundamental concept of HCC chemoprevention by ACR is "clonal deletion," which is defined as the removal of latent malignant clones from the liver before they expand into clinically detectable HCC. "Combination chemoprevention" using ACR as a key drug holds great promise of a new effective strategy for the prevention of HCC because of its synergism. ACR is also expected to prevent the development of HCC in obese people, who are at an increased risk to HCC, because this agent significantly inhibits obesity-related liver tumorigenesis in the rodent model. Here, we review the detailed effects of ACR on preventing HCC development, especially based on the results of our basic and clinical research.

Topics: Animals; Antineoplastic Agents; Carcinoma, Hepatocellular; Clonal Deletion; Humans; Liver Neoplasms; Receptors, Retinoic Acid; Retinoid X Receptors; Tretinoin

The prognosis for patients with hepatocellular carcinoma (HCC) is poor and effective prevention strategies are urgently required. Here, we review abnormalities in the expression and function of retinoids and their receptors, and how they play a critical role in the development of HCC. In particular, a malfunction of RXRalpha due to phosphorylation by Ras-MAPK signaling pathway is profoundly associated with liver carcinogenesis and thus may be a promising target for HCC chemoprevention. Acyclic retinoid (ACR), a synthetic retinoid, inhibits Ras-MAPK activation and RXRalpha phosphorylation, thereby suppressing growth in HCC-derived cells. In clinical trials, ACR has been shown to improve patient survival by preventing viral HCC development, a possible manifestation of the concept of "clonal deletion" therapy. "Combination chemoprevention" with ACR as the key drug has great potential to become an effective strategy for the prevention of liver carcinogenesis. In summary, both basic and clinical research strongly suggest that ACR plays a critical role in preventing the development of HCC and that "clonal deletion" therapy is one of the most practical approaches for this purpose.

Topics: Carcinoma, Hepatocellular; Chemoprevention; Clinical Trials as Topic; Clonal Deletion; Humans; Liver Neoplasms; Receptors, Retinoic Acid; Retinoid X Receptors; Tretinoin

Hepatocellular carcinoma (HCC) is a major health care problem worldwide. The prognosis of patients with HCC is poor because even in the early stages when surgical treatment might be expected to be curative, the incidence of recurrence in patients with underlying cirrhosis is very high due to multicentric carcinogenesis. Therefore, strategies to prevent recurrence and second primary HCC are required to improve the prognosis. One of the most practical approaches to prevent the multicentric development of HCC is 'clonal deletion' therapy, which is defined as the removal of latent (i.e. invisible) (pre)malignant clones from the liver in a hypercarcinogenic state. Retinoids, a group of structural and functional analogs of vitamin A, exert their biological function primarily through two distinct nuclear receptors, retinoic acid receptors and retinoid X receptors (RXR), and abnormalities in the expression and function of these receptors are highly associated with the development of various cancers, including HCC. In particular, a malfunction of RXRalpha due to phosphorylation by the Ras-mitogen-activated protein kinase signaling pathway is profoundly associated with the development of HCC and thus may be a critical target for HCC chemoprevention. Acyclic retinoid, which has been clinically shown to reduce the incidence of a post-therapeutic recurrence of HCC, can inhibit Ras activity and phosphorylation of the extracellular signal-regulated kinase and RXRalpha proteins. In conclusion, the inhibition of RXRalpha phosphorylation and the restoration of its physiological function as a master regulator for nuclear receptors may be a potentially effective strategy for HCC chemoprevention and clonal deletion. Acyclic retinoid, which targets phosphorylated RXRalpha, may thus play a critical role in preventing the development of multicentric HCC.

Topics: Animals; Antineoplastic Agents; Carcinoma, Hepatocellular; Chemoprevention; Humans; Liver Neoplasms; Phosphorylation; Retinoid X Receptor alpha; Tretinoin

Topics: Amino Acids, Branched-Chain; Angiotensin-Converting Enzyme Inhibitors; Antineoplastic Agents; Carcinoma, Hepatocellular; Diabetes Mellitus; Humans; Immunotherapy, Adoptive; Interferons; Lamivudine; Liver Neoplasms; Neoadjuvant Therapy; Neoplasm Recurrence, Local; Obesity; Randomized Controlled Trials as Topic; Risk Factors; Tretinoin; Vitamin K

Topics: Animals; Antineoplastic Agents; Carcinoma, Hepatocellular; Humans; Liver Neoplasms; Neoplasm Recurrence, Local; Receptors, Retinoic Acid; Retinoid X Receptors; Tretinoin

Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide and the third most common cause of cancer deaths. Surgical resection, with or without transplantation, can result in long-term survival. However, surgery can only be performed in about 15% of patients with HCC and the 5-year survival rate is only approximately 33%-50% after potentially curative resection. Percutaneous ethanol injection, radiofrequency ablation, and transarterial chemoembolization are invasive techniques that have shown efficacy in reducing tumor bulk. Similarly, systemic chemotherapy may induce tumor responses, but a survival benefit has not been clearly demonstrated. In addition, the lack of efficacy of antiandrogens, tamoxifen, and single-agent interferon has now been confirmed.Sorafenib is a multikinase inhibitor with antiangiogenic, proapoptotic, and Raf kinase inhibitory activity. In a large, multicenter, randomized, phase 3 trial there was a significant improvement in both time to disease progression and overall survival with sorafenib compared with placebo. Sorafenib is the first agent to demonstrate a consistent improvement in overall survival for patients with advanced HCC. Further studies are required to determine the role of other molecular-targeted therapies, either alone or in combination with sorafenib in patients with advanced HCC. Further studies are also required to determine the role of sorafenib in combination with locoregional therapies (eg, transarterial chemoembolization), and the role of sorafenib as adjuvant therapy following surgery.

Topics: Antineoplastic Agents; Benzenesulfonates; Carcinoma, Hepatocellular; Catheter Ablation; Chemoembolization, Therapeutic; Estrogens; Humans; Injections, Intravenous; Interferons; Liver Neoplasms; Niacinamide; Palliative Care; Phenylurea Compounds; Pyridines; Risk Factors; Sorafenib; Tretinoin

Topics: Antineoplastic Agents; Carcinoma, Hepatocellular; Chemoprevention; Fibroblast Growth Factors; Humans; Liver Neoplasms; Signal Transduction; Tretinoin

Hepatocellular carcinoma (HCC) develops frequently in the liver of patients with chronic hepatitis and cirrhosis caused by persistent infection with hepatitis B virus or hepatitis C virus in Asia. Several studies including ours have revealed that the risk of HCC increases in parallel with the progression of hepatic fibrosis associated with chronic hepatitis and liver cirrhosis. It may be delineated reasonably, therefore, that suppression of fibrosis by chemical (or biological) agents would be able to decrease the risk of HCC. We have demonstrated that antifibrotic agents, such as HOE 077, TJ-9 and interferon, can reduce the risk of HCC. Accordingly, antifibrotic agents are promising candidates for chemoprevention of HCC. The results of our study are discussed within the scope of the current state of the art as regards chemopreventing HCC.

Topics: Animals; Antineoplastic Agents; Antiviral Agents; Carcinoma, Hepatocellular; Chemoprevention; Drugs, Chinese Herbal; Forecasting; Hepatitis B; Hepatitis C; Humans; Interferons; Liver Cirrhosis, Experimental; Liver Neoplasms; Pyridines; Tretinoin

Topics: Anticarcinogenic Agents; Carcinoma, Hepatocellular; Chemoprevention; Humans; Liver Neoplasms; Tretinoin

Hepatocellular carcinoma (HCC) often develops in patients with chronic liver diseases associated with hepatitis B (HBV) and hepatitis C (HCV) virus infections with high incidences. Particularly, post-therapeutic recurrence encountered after the curative treatment of the preceding HCC may limit the prognosis. Thus, prevention of HCC is of great significance. In the present review, immunopreventions with alpha-interferon and glycyrrhizin, as well as chemoprevention with acyclic retinoid, are discussed. alpha-Interferon prevents the development of HCC not only in patients with a long-term elimination of HCV (sustained virological responders), but in ones with normalized serum aminotransferases (sustained biochemical responders). Glycyrrhizin also suppresses serum aminotransferases and thereby prevents the tumor development, even though the compound does not have antiviral activity for HBV or HCV by itself. Therefore, suppression of hepatic necroinflammation by these drugs may serve to prevent hepatocarcinogenesis. In contrast, acyclic retinoid suppresses the post-therapeutic recurrence in cirrhotic patients who underwent curative treatment of preceding tumors. The retinoid induces the disappearance of serum lectin-reactive alpha-fetoprotein (AFP-L3), a tumor marker indicating the presence of unrecognizable tumors in the remnant liver, suggesting a deletion of such minute (pre)malignant clones (clonal deletion). As a molecular mechanism of the clonal deletion, a novel mechanism of apoptosis induction by the retinoid via tissue transglutaminase is implicated. In future, a combination of immunopreventive and chemopreventive therapies may give a clue to the further advances of cancer prevention, and thereby to the improvement of the prognosis of cirrhotic patients.

Topics: alpha-Fetoproteins; Anti-Inflammatory Agents, Non-Steroidal; Antineoplastic Agents; Carcinoma, Hepatocellular; Clonal Deletion; Glycyrrhizic Acid; Humans; Interferon-alpha; Liver Neoplasms; Prognosis; Tretinoin

Topics: Antineoplastic Agents; Carcinoma, Hepatocellular; Humans; Liver Neoplasms; Neoplasms, Second Primary; Tretinoin

Effective prophylactic therapies have not been established for hepatocellular carcinoma recurrence. Peretinoin represents one novel option for patients with hepatitis C virus-related hepatocellular carcinoma (HCV-HCC), and it was tested in a multicenter, randomized, double-blind, placebo-controlled study.. Patients with curative therapy were assigned to one of the following regimens: peretinoin 600, 300 mg/day, or placebo for up to 96 weeks. The primary outcome was recurrence-free survival (RFS).. Of the 401 patients initially enrolled, 377 patients were analyzed for efficacy. The RFS rates in the 600-mg group, the 300-mg group, and the placebo group were 71.9, 63.6, and 66.0 % at 1 year, and 43.7, 24.9, and 29.3 % at 3 years, respectively. The primary comparison of peretinoin (300 and 600-mg) with placebo was not significant (P = 0.434). The dose-response relationship based on the hypothesis that "efficacy begins to increase at 600 mg/day" was significant (P = 0.023, multiplicity-adjusted P = 0.048). The hazard ratios for RFS in the 600-mg group vs. the placebo group were 0.73 [95 % confidence interval (CI) 0.51-1.03] for the entire study period and 0.27 (95 % CI 0.07-0.96) after 2 years of the randomization. Common adverse events included ascites, increased blood pressure, headache, presence of urine albumin, and increased transaminases.. Although the superiority of peretinoin to placebo could not be validated, 600 mg/day was shown to be the optimal dose, and treatment may possibly reduce the recurrence of HCV-HCC, particularly after 2 years. The efficacy and safety of peretinoin 600 mg/day should continue to be evaluated in further studies.

Topics: Aged; Anticarcinogenic Agents; Carcinoma, Hepatocellular; Disease-Free Survival; Dose-Response Relationship, Drug; Double-Blind Method; Female; Hepatitis C, Chronic; Humans; Kaplan-Meier Estimate; Liver Neoplasms; Male; Middle Aged; Neoplasm Recurrence, Local; Retinoids; Treatment Outcome

The acyclic retinoid, peretinoin, has been shown to be effective for suppressing hepatocellular carcinoma (HCC) recurrence after definitive treatment in a small-scale randomized clinical trial. However, little has been documented about the mechanism by which peretinoin exerts its inhibitory effects against recurrent HCC in humans in vivo.. Twelve hepatitis C virus-positive patients whose HCC had been eradicated through curative resection or ablation underwent liver biopsy at baseline and week 8 of treatment with either a daily dose of 300 or 600 mg peretinoin. RNA isolated from biopsy samples was subjected to gene expression profile analysis.. Peretinoin treatment elevated the expression levels of IGFBP6, RBP1, PRB4, CEBPA, G0S2, TGM2, GPRC5A, CYP26B1, and many other retinoid target genes. Elevated expression was also observed for interferon-, Wnt-, and tumor suppressor-related genes. By contrast, decreased expression levels were found for mTOR- and tumor progression-related genes. Interestingly, gene expression profiles for week 8 of peretinoin treatment could be classified into two groups of recurrence and non-recurrence with a prediction accuracy rate of 79.6% (P<0.05). In the liver of patients with non-recurrence, expression of PDGFC and other angiogenesis genes, cancer stem cell marker genes, and genes related to tumor progression was down-regulated, while expression of genes related to hepatocyte differentiation, tumor suppression genes, and other genes related to apoptosis induction was up-regulated.. Gene expression profiling at week 8 of peretinoin treatment could successfully predict HCC recurrence within 2 years. This study is the first to show the effect of peretinoin in suppressing HCC recurrence in vivo based on gene expression profiles and provides a molecular basis for understanding the efficacy of peretinoin.

Topics: Aged; Analysis of Variance; Antineoplastic Agents; Carcinoma, Hepatocellular; Female; Gene Expression; Gene Expression Profiling; Hepatitis C, Chronic; Humans; Liver Neoplasms; Male; Middle Aged; Neoplasm Recurrence, Local; Oligonucleotide Array Sequence Analysis; Retinoids

Oral administration with acyclic retinoid, a synthetic vitamin A analog, for a limited period of 12 months (48 weeks) prevented the development of second primary hepatocellular carcinoma (HCC) and also improved the survival of patients who underwent curative treatments of the initial tumor. Following that randomized controlled study reported in 1996 and 1999, we have continued to follow up the patients by medical imaging and blood chemical analyses, and found that the preventive effect of acyclic retinoid lasted up to 199 weeks after randomization (or 151 weeks after completion of retinoid administration). The retinoid's effect was not mediated by reduction in hepatic necro-inflammation since no significant decrease in serum aminotransferase activity was seen in the retinoid group. Such observation seems quite distinct from the cancer-preventive mechanism of interferon, a potent immunopreventive agent for HCC. We have also shown here the reduction by the retinoid in serum levels of lectin-reactive alpha-fetoprotein (AFP-L3) and protein induced by vitamin K absence or antagonist-II (PIVKA-II), both of which indicate the presence of latent HCC cells. These results suggest that acyclic retinoid may delete such malignant clones before they expand to clinically detectable tumors and thereby inhibited second primary HCC. Once such latent clones are eradicated, it may well take at least several years for the next cancer clone to arise clinically. This may possibly explain a reason for the long-term effect of the retinoid even after the limited period of administration.

Topics: alpha-Fetoproteins; Antineoplastic Agents; Aspartate Aminotransferases; Biomarkers; Carcinoma, Hepatocellular; Humans; Japan; Liver Neoplasms; Neoplasms, Second Primary; Protein Precursors; Prothrombin; Survival Analysis; Tretinoin

A goal of cancer chemoprevention is the deletion of latent premalignant or malignant clones before they expand to a clinically detectable tumor. However, such clonal deletion has not been demonstrated in clinical studies. We have evaluated serum levels of lectin-reactive alpha-fetoprotein (AFP-L3), which suggests the presence of latent hepatoma cells, in a randomized controlled trial that used acyclic retinoid to prevent second primary hepatomas in patients who had received treatments that cured initial hepatomas. The trial involved 21 patients in each acyclic retinoid (600 mg daily) and placebo group and consisted of a 12-month period of drug administration and a subsequent follow-up period. Serum AFP-L3 was determined at entry and at the end of the 12-month treatment period using lectin-affinity electrophoresis and antibody-affinity blotting. Although neither treatment affected serum levels of total AFP, acyclic retinoid significantly reduced AFP-L3 levels after a 12-month administration (P < 0.01). Acyclic retinoid not only deleted AFP-L3 from patients who had been positive for AFP-L3 at entry but also prevented the appearance of AFP-L3 in patients who had been negative at entry (P < 0.01). In contrast, placebo significantly raised the incidence of AFP-L3-positive patients after a 12-month administration from that at entry (P < 0.05). Patients positive for AFP-L3 after a 12-month treatment had a significantly higher risk of second primary hepatomas in the subsequent follow-up period (P = 0.03). Acyclic retinoid may have deleted a clone of latent hepatoma cells producing AFP-L3 and thereby inhibited second primary hepatomas. Serum AFP-L3 may be a useful intermediate biomarker in the chemoprevention of second primary hepatomas by acyclic retinoid.

Topics: alpha-Fetoproteins; Antineoplastic Agents; Carcinoma, Hepatocellular; Disease-Free Survival; Female; Follow-Up Studies; Humans; Lectins; Liver Neoplasms; Male; Middle Aged; Neoplasms, Second Primary; Placebos; Time Factors; Tretinoin

In patients with hepatocellular carcinoma (hepatoma), the rate of recurrent and second primary hepatomas is high despite surgical resection and percutaneous ethanol-injection therapy. We developed an acyclic retinoid, polyprenoic acid, that inhibits hepatocarcinogenesis in the laboratory and induces differentiation and apoptosis in cell lines derived from human hepatoma. In a randomized, controlled study, we tested whether the compound reduced the incidence of recurrent and second primary hepatomas after curative treatment.. We prospectively studied 89 patients who were free of disease after surgical resection of a primary hepatoma or the percutaneous injection of ethanol. We randomly assigned the patients to receive either polyprenoic acid (600 mg daily) or placebo for 12 months. We studied the remnant liver by ultrasonography every three months after randomization. The primary end point of the study was the appearance of a histologically confirmed recurrent or new hepatoma.. Treatment with polyprenoic acid significantly reduced the incidence of recurrent or new hepatomas. After a median follow-up of 38 months, 12 patients in the polyprenoic acid group (27 percent) had recurrent or new hepatomas as compared with 22 patients in the placebo group (49 percent, P = 0.04). The most striking difference was in the groups that had second primary hepatomas--7 in the group receiving polyprenoic acid as compared with 20 in the placebo group (P = 0.04 by the log-rank test). Cox proportional-hazards analysis demonstrated that as an independent factor, polyprenoic acid reduced the occurrence of second primary hepatomas (adjusted relative risk, 0.31; 95 percent confidence interval, 0.12 to 0.78).. Oral polyprenoic acid prevents second primary hepatomas after surgical resection of the original tumor or the percutaneous injection of ethanol.

Topics: Aged; Carcinoma, Hepatocellular; Embolization, Therapeutic; Ethanol; Female; Follow-Up Studies; Humans; Injections, Intralesional; Liver Neoplasms; Male; Middle Aged; Neoplasm Recurrence, Local; Neoplasms, Second Primary; Proportional Hazards Models; Prospective Studies; Survival Analysis; Treatment Outcome; Tretinoin

Transglutaminase 2 (TG2) is a multifunctional protein that promotes or suppresses tumorigenesis, depending on intracellular location and conformational structure. Acyclic retinoid (ACR) is an orally administered vitamin A derivative that prevents hepatocellular carcinoma (HCC) recurrence by targeting liver cancer stem cells (CSCs). In this study, we examined the subcellular location-dependent effects of ACR on TG2 activity at a structural level and characterized the functional role of TG2 and its downstream molecular mechanism in the selective depletion of liver CSCs. A binding assay with high-performance magnetic nanobeads and structural dynamic analysis with native gel electrophoresis and size-exclusion chromatography-coupled multi-angle light scattering or small-angle X-ray scattering showed that ACR binds directly to TG2, induces oligomer formation of TG2, and inhibits the transamidase activity of cytoplasmic TG2 in HCC cells. The loss-of-function of TG2 suppressed the expression of stemness-related genes, spheroid proliferation and selectively induced cell death in an EpCAM+ liver CSC subpopulation in HCC cells. Proteome analysis revealed that TG2 inhibition suppressed the gene and protein expression of exostosin glycosyltransferase 1 (EXT1) and heparan sulfate biosynthesis in HCC cells. In contrast, high levels of ACR increased intracellular Ca

Topics: Carcinoma, Hepatocellular; Glycosyltransferases; Humans; Liver Neoplasms; Neoplastic Stem Cells; Protein Glutamine gamma Glutamyltransferase 2

Hepatocellular carcinoma (HCC) is a highly lethal cancer that has a high rate of recurrence, in part because of cancer stem cell (CSC)-dependent field cancerization. Acyclic retinoid (ACR) is a synthetic vitamin A-like compound capable of preventing the recurrence of HCC. Here, we performed a genome-wide transcriptome screen and showed that ACR selectively suppressed the expression of MYCN, a member of the MYC family of basic helix-loop-helix-zipper transcription factors, in HCC cell cultures, animal models, and liver biopsies obtained from HCC patients. MYCN expression in human HCC was correlated positively with both CSC and Wnt/β-catenin signaling markers but negatively with mature hepatocyte markers. Functional analysis showed repressed cell-cycle progression, proliferation, and colony formation, activated caspase-8, and induced cell death in HCC cells following silencing of MYCN expression. High-content single-cell imaging analysis and flow cytometric analysis identified a MYCN

Topics: Animals; Antineoplastic Agents; Carcinoma, Hepatocellular; Epithelial Cell Adhesion Molecule; Gene Expression Regulation, Neoplastic; Humans; Liver Neoplasms; N-Myc Proto-Oncogene Protein; Neoplasm Metastasis; Neoplastic Stem Cells; Prognosis; Tretinoin; Wnt Signaling Pathway

The pathogenesis of non-alcoholic steatohepatitis (NASH) is still unclear and the prevention of the development of hepatocellular carcinoma (HCC) has not been established. We established an atherogenic and high-fat diet mouse model that develops hepatic steatosis, inflammation, fibrosis, and liver tumors at a high frequency. Using two NASH-HCC mouse models, we showed that peretinoin, an acyclic retinoid, significantly improved liver histology and reduced the incidence of liver tumors. Interestingly, we found that peretinoin induced autophagy in the liver of mice, which was characterized by the increased co-localized expression of microtubule-associated protein light chain 3B-II and lysosome-associated membrane protein 2, and increased autophagosome formation and autophagy flux in the liver. These findings were confirmed using primary mouse hepatocytes. Among representative autophagy pathways, the autophagy related (Atg) 5-Atg12-Atg16L1 pathway was impaired; especially, Atg16L1 was repressed at both the mRNA and protein level. Decreased Atg16L1 mRNA expression was also found in the liver of patients with NASH according to disease progression. Promoter analysis revealed that peretinoin activated the promoter of Atg16L1 by increasing the expression of CCAAT/enhancer-binding-protein-alpha. Interestingly, Atg16L1 overexpression in HepG2 cells inhibited palmitate-induced NF-kB activation and interleukin-6-induced STAT3 activation. We showed that Atg16L1 induced the de-phosphorylation of Gp130, a receptor subunit of interleukin-6 family cytokines, which subsequently repressed phosphorylated-STAT3 (Tyr705) levels, and this process might be independent of autophagy function. Thus, peretinoin prevents the progression of NASH and the development of HCC through activating the autophagy pathway by increased Atg16L1 expression, which is an essential regulator of autophagy and anti-inflammatory proteins.

Topics: Animals; Autophagy; Autophagy-Related Proteins; Carcinoma, Hepatocellular; Carrier Proteins; Cells, Cultured; Diet, Atherogenic; Diet, High-Fat; Gene Expression Profiling; Hep G2 Cells; Hepatocytes; Humans; Liver; Liver Neoplasms; Male; Mice, Inbred C57BL; Non-alcoholic Fatty Liver Disease; Retinoids; RNA Interference

Sphingosine-1-phospate is a potent bioactive lipid metabolite that regulates cancer progression. Because sphingosine kinase 1 and sphingosine kinase 2 (SPHK 1/2) are both essential for sphingosine-1-phospate production, they could be a therapeutic target in various cancers. Peretinoin, an acyclic retinoid, inhibits post-therapeutic recurrence of hepatocellular carcinoma via unclear mechanisms. In this study, we assessed effects of peretinoin on SPHK expression and liver cancer development in vitro and in vivo. We examined effects of peretinoin on expression, enzymatic and promoter activity of SPHK1 in a human hepatoma cell line, Huh-7. We also investigated effects of SPHK1 on hepatocarcinogenesis induced by diethylnitrosamine using SPHK1 knockout mice. Peretinoin treatment of Huh-7 cells reduced mRNA levels, protein expression and enzymatic activity of SPHK1. Peretinoin reduced SPHK1 promoter activity; this effect of peretinoin was blocked by overexpression of Sp1, a transcription factor. Deletion of all Sp1 binding sites within the SPHK1 promoter region abolished SPHK1 promoter activity, suggesting that peretinoin reduced mRNA levels of SPHK1 via Sp1. Additionally, diethylnitrosamine-induced hepatoma was fewer and less frequent in SPHK1 knockout compared to wild-type mice. Our data showed crucial roles of SPHK1 in hepatocarcinogenesis and suggests that peretinoin prevents hepatocarcinogenesis by suppressing mRNA levels of SPHK1.

Topics: Animals; Antineoplastic Agents; Carcinoma, Hepatocellular; Cell Line, Tumor; Diethylnitrosamine; Gene Expression Regulation, Enzymologic; Hepatitis C; Humans; Liver; Liver Cirrhosis; Liver Neoplasms; Liver Neoplasms, Experimental; Mice, Knockout; Mice, Transgenic; Phosphotransferases (Alcohol Group Acceptor); Retinoids; Sphingolipids

Acyclic retinoid (ACR) is a promising drug under clinical trials for preventing recurrence of hepatocellular carcinoma. The objective of this study was to gain insights into molecular basis of the antitumorigenic action of ACR from a metabolic point of view. To achieve this, comprehensive cationic and lipophilic liver metabolic profiling was performed in mouse diethylnitrosamine (DEN)-induced hepatic tumorigenesis model using both capillary electrophoresis time-of-flight mass spectrometry and liquid chromatography time-of-flight mass spectrometry. ACR significantly counteracted against acceleration of lipogenesis but not glucose metabolism in DEN-treated mice liver, suggesting an important role of lipid metabolic reprogramming in the initiation step of hepatic tumorigenesis. Knowledge-based pathway analysis suggested that inhibition of linoleic acid metabolites such as arachidonic acid, a proinflammatory precursor, played a crucial role in the prevention by ACR of DEN-induced chronic inflammation-mediated tumorigenesis of the liver. As a molecular mechanism of the ACR's effect to prevent the aberrant lipogenesis, microarray analysis identified that a key transcription regulator of both embryogenesis and tumorigenesis, COUP transcription factor 2, also known as NR2F2, was associated with the metabolic effect of ACR in human hepatocellular carcinoma cells. Our study provided potential therapeutic targets for the chemoprevention of hepatocellular carcinoma as well as new insights into the mechanisms underlying prevention of hepatic tumorigenesis.

Topics: Alkylating Agents; Animals; Antineoplastic Agents; Blotting, Western; Carcinogenesis; Carcinoma, Hepatocellular; Chromatography, Liquid; Diethylnitrosamine; Lipogenesis; Liver Neoplasms, Experimental; Male; Metabolome; Metabolomics; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Obese; Real-Time Polymerase Chain Reaction; Receptors, Leptin; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Tretinoin; Tumor Cells, Cultured

This study examined the effects of peretinoin, an acyclic retinoid, on the survival of patients with hepatitis C virus-related hepatocellular carcinoma (HCC) who had completed curative therapy and participated in a randomized, placebo-controlled trial.. This study was an investigator-initiated retrospective cohort study. Subjects were all patients who were administered the investigational drug (peretinoin 600 mg/day, peretinoin 300 mg/day, or placebo) in the randomized trial. Survivals between the groups were compared using the log-rank test, and hazard ratios were estimated by Cox regression.. Survey data were collected from all patients (n = 392) who participated in the randomized trial, all of whom were then divided into the peretinoin 600 mg/day (n = 132), peretinoin 300 mg/day (n = 131), and placebo (n = 129) groups. At the median follow-up of 4.9 years, 5-year cumulative survival rates for patients in the 600 mg/day, 300 mg/day, and placebo groups were 73.9, 56.8, and 64.3 %, respectively. Comparison of overall survival among patients classified as Child-Pugh A revealed that survival of the 600 mg/day group (n = 105) was significantly longer than that of the placebo group (n = 108) (hazard ratio 0.575, 95 % CI 0.341-0.967; P = 0.0347).. Administration of 600 mg/day peretinoin to patients with hepatitis C virus-related HCC who have completed curative therapy may improve survival for those classified as Child-Pugh A, for whom liver function is relatively stable.

Topics: Aged; Anticarcinogenic Agents; Carcinoma, Hepatocellular; Cohort Studies; Dose-Response Relationship, Drug; Female; Follow-Up Studies; Hepatitis C; Humans; Liver Neoplasms; Male; Proportional Hazards Models; Randomized Controlled Trials as Topic; Retinoids; Retrospective Studies; Survival Rate

To improve the outcome of cancer chemotherapy, strategies to enhance the efficacy of anticancer drugs are required. Sorafenib is the only drug to prolong overall survival of the patients with hepatocellular carcinoma (HCC), however, the outcome is still not satisfactory. Retinoids, vitamin A derivatives, have been known to exhibit inhibitory effects on various cancers including HCC. In this study, we investigated the effects of combined treatment using sorafenib and retinoids including all-trans retinoic acid (ATRA), NIK-333, and Am80 on HCC cells. Cell viability assays in six HCC cell lines, HepG2, PLC/PRF/5, HuH6, HLE, HLF, and Hep3B, revealed that 5 and 10 μM ATRA, concentrations that do not exert cytotoxic effects, enhanced the cytotoxicity of sorafenib, being much more effective than NIK-333 and Am80. We found that ATRA induced AMP-activated protein kinase activation, which was followed by reduced intracellular ATP level. Gene expression analysis revealed that ATRA decreased the expression of glycolytic genes such as GLUT-1 and LDHA. In the combination treatment using ATRA and sorafenib, increased apoptosis, followed by the activation of p38 MAPK and JNK, the upregulation and translocation of Bax to mitochondria, and the activation of caspase-3, was observed. Suppression of AMP-activated protein kinase by siRNA restored the viability of the cells treated with ATRA and sorafenib. Our results thus indicate that ATRA is useful for enhancing the cytotoxicity of sorafenib against HCC cells by regulating the energy metabolism of HCC cells.

Topics: Adenosine Triphosphate; AMP-Activated Protein Kinases; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; bcl-2-Associated X Protein; Benzoates; Carcinoma, Hepatocellular; Cell Line, Tumor; Gene Expression Regulation, Neoplastic; Glucose Transporter Type 1; Humans; Liver Neoplasms; Niacinamide; Phenylurea Compounds; Retinoids; Sorafenib; Tetrahydronaphthalenes; Tretinoin

Nuclear accumulation of transglutaminase 2 (TG2) is an important step in TG2-dependent cell death. However, the underlying molecular mechanisms for nuclear translocation of TG2 are still poorly understood. In this study, we demonstrated that acyclic retinoid (ACR) induced nuclear accumulation of TG2 in JHH-7 cells, a hepatocellular carcinoma (HCC) leading to their apoptosis. We further demonstrated molecular mechanism in nuclear-cytoplasmic trafficking of TG2 and an effect of ACR on it. We identified a novel 14-amino acid nuclear localization signal (NLS) (466)AEKEETGMAMRIRV(479) in the 'C' domain and a leucine-rich nuclear export signal (NES) (657)LHMGLHKL(664) in the 'D' domain that allowed TG2 to shuttle between the nuclear and cytosolic milieu. Increased nuclear import of GAPDH myc-HIS fused with the identified NLS was observed, confirming its nuclear import ability. Leptomycin B, an inhibitor of exportin-1 as well as point mutation of all leucine residues to glutamine residues in the NES of TG2 demolished its nuclear export. TG2 formed a trimeric complex with importin-α and importin-β independently from transamidase activity which strongly suggested the involvement of a NLS-based translocation of TG2 to the nucleus. ACR accelerated the formation of the trimeric complex and that may be at least in part responsible for enhanced nuclear localization of TG2 in HCC cells treated with ACR.

Topics: Amino Acid Sequence; Apoptosis; Carcinoma, Hepatocellular; Cell Differentiation; Cell Line, Tumor; Cell Nucleus; Cell Proliferation; GTP-Binding Proteins; Humans; Liver Neoplasms; Molecular Sequence Data; Protein Glutamine gamma Glutamyltransferase 2; Transglutaminases; Tretinoin

Clinical studies suggest that the oral acyclic retinoid Peretinoin may reduce the recurrence of hepatocellular carcinoma (HCC) following surgical ablation of primary tumours. Since hepatitis C virus (HCV) infection is a major cause of HCC, we assessed whether Peretinoin and other retinoids have any effect on HCV infection. For this purpose, we measured the effects of several retinoids on the replication of genotype 1a, 1b, and 2a HCV in vitro. Peretinoin inhibited RNA replication for all genotypes and showed the strongest antiviral effect among the retinoids tested. Furthermore, it reduced infectious virus release by 80-90% without affecting virus assembly. These effects could be due to reduced signalling from lipid droplets, triglyceride abundance, and the expression of mature sterol regulatory element-binding protein 1c and fatty acid synthase. These negative effects of Peretinoin on HCV infection may be beneficial in addition to its potential for HCC chemoprevention in HCV-infected patients.

Topics: Anticarcinogenic Agents; Antiviral Agents; Carcinoma, Hepatocellular; Hepacivirus; Hepatitis C; Humans; Interferon alpha-2; Interferon-alpha; Lipid Metabolism; Liver Neoplasms; Neoplasm Recurrence, Local; Peptide Chain Elongation, Translational; Recombinant Proteins; Retinoids; RNA, Viral; STAT1 Transcription Factor; Sterol Regulatory Element Binding Protein 1; Virus Assembly; Virus Release; Virus Replication

The prognosis of patients with hepatocellular carcinoma (HCC) is poor and the development of effective treatments for this malignancy, including combination chemotherapy, is required. This study examined the possible combined inhibitory effects of bevacizumab, an anti-vascular endothelial growth factor monoclonal antibody, and acyclic retinoid (ACR), which can prevent the development of HCC, on the growth of Huh7 human HCC cells. Xenograft tumors were produced by subcutaneously injecting Huh7 cells into nude mice. Starting 1 wk after the tumor cell injection, the mice were treated with bevacizumab alone (5 mg/kg body weight, subcutaneous injection, twice a week), ACR alone (given in a diet containing 0.03%), or their combination for 6 wk, and the effects of these regimens on xenograft growth were examined. Combined treatment with bevacizumab plus ACR significantly suppressed the growth of Huh7 xenografts. The combination of these agents significantly inhibited the phosphorylation of the Akt protein in tumor tissues. With combination therapy, the population of Ki-67-positive cells in xenografts decreased, while that of TUNEL-positive cells increased. The combination of bevacizumab and ACR exerts growth-suppressing effects on HCC cells by inhibiting cell proliferation and inducing apoptosis. This combination might be an effective regimen for the treatment of HCC.

Topics: Animals; Antibodies, Monoclonal, Humanized; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Bevacizumab; Carcinoma, Hepatocellular; Cell Line, Tumor; Cell Proliferation; Mice; Mice, Nude; Neoplasm Transplantation; Phosphorylation; Proto-Oncogene Proteins c-akt; Tretinoin; Vascular Endothelial Growth Factor A

A malfunction of RXRα due to phosphorylation is associated with liver carcinogenesis, and acyclic retinoid (ACR), which targets RXRα, can prevent the development of hepatocellular carcinoma (HCC). Activation of PI3K/Akt signaling plays a critical role in the proliferation and survival of HCC cells. The present study examined the possible combined effects of ACR and LY294002, a PI3K inhibitor, on the growth of human HCC cells.. This study examined the effects of the combination of ACR plus LY294002 on the growth of HLF human HCC cells.. ACR and LY294002 preferentially inhibited the growth of HLF cells in comparison with Hc normal hepatocytes. The combination of 1 μM ACR and 5 μM LY294002, in which the concentrations used are less than the IC₅₀ values of these agents, synergistically inhibited the growth of HLF, Hep3B, and Huh7 human HCC cells. These agents when administered in combination acted cooperatively to induce apoptosis in HLF cells. The phosphorylation of RXRα, Akt, and ERK proteins in HLF cells were markedly inhibited by treatment with ACR plus LY294002. Moreover, this combination also increased RXRE promoter activity and the cellular levels of RARβ and p21(CIP1), while decreasing the levels of cyclin D1.. ACR and LY294002 cooperatively increase the expression of RARβ, while inhibiting the phosphorylation of RXRα, and that these effects are associated with the induction of apoptosis and the inhibition of cell growth in human HCC cells. This combination might therefore be effective for the chemoprevention and chemotherapy of HCC.

Topics: Apoptosis; Carcinoma, Hepatocellular; Cell Line, Tumor; Cell Proliferation; Chromones; Cyclin D1; Cyclin-Dependent Kinase Inhibitor p21; Drug Synergism; Extracellular Signal-Regulated MAP Kinases; Hepatocytes; Humans; Liver Neoplasms; Morpholines; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Phosphorylation; Proto-Oncogene Proteins c-akt; Retinoid X Receptor alpha; Retinoid X Receptor beta; Tretinoin

Hepatocellular carcinoma has a high mortality rate due to its rate of recurrence. Acyclic retinoid prevents recurrence of hepatocellular carcinoma in patients after surgical removal of their primary tumors by inducing apoptosis in hepatocellular carcinoma cells, although the molecular mechanisms of action are not understood.. Human hepatocellular carcinoma cells in culture, as well as nude mice transplanted with hepatocellular carcinoma cells and rats given with N-diethylnitrosamine were treated with acyclic retinoid. Changes in activated caspase 3 and transglutaminase 2 (TG2) levels, Sp1 cross-linking and its activities, expression of epidermal growth factor receptor, and apoptotic levels were measured.. Acyclic retinoid simultaneously stimulated the activation of caspase 3, and the expression, nuclear localization and crosslinking activity of TG2, resulting in crosslinking and inactivation of the transcription factor, Sp1, thereby reducing expression of epidermal growth factor receptor and cell death in three hepatocellular carcinoma cell lines. These effects were partially restored by a caspase inhibitor, transfection of antisense TG2, restoration of functional Sp1, or an excess of epidermal growth factor. Nuclear expression of TG2 and crosslinked Sp1, as also activated caspase 3 were found in both hepatocellular carcinoma cells transplanted into nude mice and cancerous regions within the liver in N-diethylnitrosamine-induced hepatocarcinogenesis model in rats, following treatment of animals with acyclic retinoid.. Treatment with acyclic retinoid produces a dual activation of caspase 3 and TG2 induced apoptosis of hepatocellular carcinoma cells via modification and inactivation of Sp1, resulting in reduced expression of epidermal growth factor receptor.

Topics: Animals; Antineoplastic Agents; Apoptosis; Carcinoma, Hepatocellular; Caspase 3; Diethylnitrosamine; Down-Regulation; ErbB Receptors; Gene Knockdown Techniques; GTP-Binding Proteins; Humans; Liver Neoplasms, Experimental; Mice; Mice, Inbred BALB C; Mice, Nude; Neoplasm Transplantation; Protein Glutamine gamma Glutamyltransferase 2; Rats; Retinoid X Receptor alpha; Sp1 Transcription Factor; Transglutaminases; Tretinoin; Tumor Cells, Cultured; Up-Regulation

Acyclic retinoid (ACR) is currently under clinical trial as an agent to suppress the recurrence of hepatocellular carcinoma (HCC) through its ability to induce apoptosis in premature HCC cells. ACR has an anticancer effect in vivo as well, although it shows weak apoptosis-inducing activity against mature HCC cells, suggesting the existence of an additional action mechanism. In this study, we investigated the antiangiogenic activity of ACR. ACR inhibited angiogenesis within chicken chorioallantoic membrane (CAM) in as similar a manner as all-trans retinoic acid (atRA). Although suppression of angiogenesis by atRA was partially rescued by the simultaneous addition of angiopoietin-1, suppression of angiogenesis by ACR was not rescued under the same condition at all. Conversely, although suppression of angiogenesis by ACR was partially inverted by the simultaneous addition of vascular endothelial growth factor (VEGF), suppression of angiogenesis by atRA was not affected under the same condition. These results suggested that mechanisms underlying the suppression of angiogenesis by ACR and atRA were different. ACR selectively inhibited the phosphorylation of VEGF receptor 2 (VEGFR2) and of extracellular signal-regulated kinase (ERK) without changing their protein expression levels, and inhibited endothelial cell growth, migration, and tube formation. The inhibition of the phosphorylation of ERK, endothelial growth, migration, tube formation, and angiogenesis by ACR was rescued by the overexpression of constitutively active mitogen-activated protein kinase (MAPK). Finally, ACR, but not atRA, inhibited HCC-induced angiogenesis in a xenografted CAM model. These results delineate the novel activity of ACR as an antiangiogenic through a strong inhibition of the VEGFR2 MAPK pathway.

Topics: Angiogenesis Inhibitors; Animals; Aorta; Carcinoma, Hepatocellular; Cattle; Cell Division; Cell Movement; Cells, Cultured; Chick Embryo; Chorioallantoic Membrane; Endothelial Cells; Extracellular Signal-Regulated MAP Kinases; Humans; Liver Neoplasms, Experimental; Mitogen-Activated Protein Kinases; Neoplasm Transplantation; Neovascularization, Pathologic; Neovascularization, Physiologic; Phosphorylation; Transplantation, Heterologous; Tretinoin; Umbilical Veins; Vascular Endothelial Growth Factor Receptor-2

A malfunction of retinoid X receptor-alpha (RXRalpha) due to phosphorylation is associated with the development of hepatocellular carcinoma (HCC) and acyclic retinoid (ACR), which targets RXRalpha, can prevent the development of second primary HCC. Valproic acid (VPA), a histone deacetylase (HDAC) inhibitor, induces apoptosis and cell cycle arrest in cancer cells. VPA can also enhance the sensitivity of cancer cells to retinoids. The present study examined the possible combined effects of ACR plus VPA in HepG2 human HCC cell line. The combination of 5muM ACR and 1mM VPA, about the IC(25) value for both compounds, synergistically inhibited the growth of HepG2 cells without affecting the growth of Hc normal human hepatocytes. The combined treatment with ACR plus VPA also acted synergistically to induce apoptosis and G(0)-G(1) cell cycle arrest in HepG2 cells. This combination further exerted a synergistic inhibition of the phosphorylation of RXRalpha, ERK, Akt and GSK-3beta proteins and caused an accumulation of acetylated histones H3 and H4 proteins. VPA enhanced the ability of ACR to raise the cellular levels of RARbeta and p21(CIP1). The combination of these agents markedly increased both the RARE and RXRE promoter activities in HepG2 cells. These results suggest that ACR and VPA cooperatively increase the expression of RARbeta and p21(CIP1), while inhibiting the phosphorylation of RXRalpha, and these effects were associated with induction of apoptosis and the inhibition of cell growth in HepG2 cells. This combination might therefore be an effective regimen for the chemoprevention and chemotherapy of HCC.

Topics: Antineoplastic Combined Chemotherapy Protocols; Blotting, Western; Carcinoma, Hepatocellular; Cell Line, Tumor; Cell Proliferation; Drug Synergism; Humans; In Situ Nick-End Labeling; Liver Neoplasms; Reverse Transcriptase Polymerase Chain Reaction; Tretinoin; Valproic Acid

Hepatocellular carcinoma (HCC) is one of the most prevalent cancers worldwide. However, effective chemopreventive and chemotherapeutic agents for this cancer have not yet been developed. In clinical trials acyclic retinoid (ACR) and vitamin K(2) (VK(2)) decreased the recurrence rate of HCC. In the present study we examined the possible combined effects of ACR or another retinoid 9-cis retinoic acid (9cRA) plus VK(2) in the HuH7 human HCC cell line. We found that the combination of 1.0 microM ACR or 1.0 microM 9cRA plus 10 microM VK(2) synergistically inhibited the growth of HuH7 cells without affecting the growth of Hc normal human hepatocytes. The combined treatment with ACR plus VK(2) also acted synergistically to induce apoptosis in HuH7 cells. Treatment with VK(2) alone inhibited phosphorylation of the retinoid X receptor (RXR)alpha protein, which is regarded as a critical factor for liver carcinogenesis, through inhibition of Ras activation and extracellular signal-regulated kinase phosphorylation. Moreover, the inhibition of RXRalpha phosphorylation by VK(2) was enhanced when the cells were cotreated with ACR. The combination of retinoids plus VK(2) markedly increased both the retinoic acid receptor responsive element and retinoid X receptor responsive element promoter activities in HuH7 cells. Our results suggest that retinoids (especially ACR) and VK(2) cooperatively inhibit activation of the Ras/MAPK signaling pathway, subsequently inhibiting the phosphorylation of RXRalpha and the growth of HCC cells. This combination might therefore be effective for the chemoprevention and chemotherapy of HCC.

Topics: Antineoplastic Agents; Carcinoma, Hepatocellular; Cell Line, Tumor; Dose-Response Relationship, Drug; Drug Synergism; Humans; Liver Neoplasms; Tretinoin; Vitamin K 2

Hepatocellular carcinoma (HCC) is one of the most common human malignancies. Its high mortality rate is mainly a result of high intrahepatic recurrence. The novel synthetic retinoid acyclic retinoid (ACR) has been reported to prevent the recurrence of human HCC after surgical resection of primary tumors, but the molecular mechanisms underlying its effects remain to be elucidated. In this study, we clarified the molecular targets of ACR.. The inhibitory effects by ACR on growth were examined. Intracellular signaling induced by ACR was comprehensively studied by a reporter assay. Gene expression changes by ACR were examined using a microarray. From these results, a candidate signaling pathway modulated by ACR was determined and whether antagonizing this pathway reverses the effect was examined.. We show that ACR inhibits the growth of HCC cells through the down-regulation of fibroblast growth factor (FGF) receptor 3 expression and FGF-mediated signaling, which in turn suppresses the activity of Rho and serum response factor-mediated transcription. Conversely, overexpression of the active form of FGF receptor 3 or the addition of FGF reverses the ACR-mediated inhibition of growth. In addition, silencing the FGF receptor 3 gene by RNA interference inhibits cell growth.. These studies show that ACR is a potent inhibitor of FGF signaling and that selective blocking of the FGF-mediated pathway could be a promising therapeutic approach for the management of patients with HCC.

Topics: Antineoplastic Agents; Carcinoma, Hepatocellular; Cell Line, Tumor; Cell Proliferation; Down-Regulation; Fibroblast Growth Factors; Gene Expression; Humans; Liver Neoplasms; Neoplasm Recurrence, Local; Oligonucleotide Array Sequence Analysis; Protein-Tyrosine Kinases; Receptor, Fibroblast Growth Factor, Type 3; Receptors, Fibroblast Growth Factor; rho GTP-Binding Proteins; Signal Transduction; Tretinoin

Hepatoma is one of the most frequently occurring cancers worldwide. However, effective chemotherapeutic agents for this disease have not been developed. Acyclic retinoid, a novel synthetic retinoid, can reduce the incidence of postsurgical recurrence of hepatoma and improve the survival rate. OSI-461, a potent derivative of exisulind, can increase intracellular levels of cyclic GMP, which leads to activation of protein kinase G and induction of apoptosis in cancer cells. In the present study, we examined the combined effects of acyclic retinoid plus OSI-461 in the HepG2 human hepatoma cell line. We found that the combination of as little as 1.0 micromol/L acyclic retinoid and 0.01 micromol/L OSI-461 exerted synergistic inhibition of the growth of HepG2 cells. Combined treatment with low concentrations of these two agents also acted synergistically to induce apoptosis in HepG2 cells through induction of Bax and Apaf-1, reduction of Bcl-2 and Bcl-xL, and activation of caspase-3, -8, and -9. OSI-461 enhanced the G0-G1 arrest caused by acyclic retinoid, and the combination of these agents caused a synergistic decrease in the levels of expression of cyclin D1 protein and mRNA, inhibited cyclin D1 promoter activity, decreased the level of hyperphosphorylated forms of the Rb protein, induced increased cellular levels of the p21(CIP1) protein and mRNA, and stimulated p21(CIP1) promoter activity. Moreover, OSI-461 enhanced the ability of acyclic retinoid to induce increased cellular levels of retinoic acid receptor beta and to stimulate retinoic acid response element-chloramphenicol acetyltransferase activity. A hypothetical model involving concerted effects on p21(CIP1) and retinoic acid receptor beta expression is proposed to explain these synergistic effects. Our results suggest that the combination of acyclic retinoid plus OSI-461 might be an effective regimen for the chemoprevention and chemotherapy of human hepatoma and possibly other malignancies.

Topics: Antineoplastic Agents; Apoptosis; beta Catenin; Blotting, Western; Carcinoma, Hepatocellular; Cell Adhesion Molecules; Cell Cycle Proteins; Cell Line, Tumor; Cell Proliferation; Chloramphenicol O-Acetyltransferase; Cyclic GMP; Cyclin D1; Cyclin-Dependent Kinase Inhibitor p21; Cytoskeletal Proteins; Dose-Response Relationship, Drug; Drug Synergism; G1 Phase; Gene Expression Regulation, Neoplastic; Humans; Intracellular Space; Liver Neoplasms; Microfilament Proteins; Models, Biological; Phosphoproteins; Phosphorylation; Promoter Regions, Genetic; Receptors, Retinoic Acid; Recombinant Fusion Proteins; Response Elements; Resting Phase, Cell Cycle; Retinoblastoma Protein; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sulindac; Trans-Activators; Transfection; Tretinoin; Tumor Suppressor Protein p53

We have reported previously that acyclic retinoid, a synthetic retinoid X receptor alpha (RXRalpha)-ligand, suppresses the development of hepatocellular carcinoma (HCC) in patients with chronic liver disease. On the other hand, HCCs become refractory to physiological concentrations of the natural RXRalpha-ligand, 9-cis retinoic acid (9cRA), due to extracellular signal-regulated kinase (Erk) 1/2-mediated phosphorylation and inactivation of RXRalpha. Here, we show that acyclic retinoid restores the function of RXRalpha in human HCC-derived HuH7 cells by inactivating the Ras-Erk 1/2 signaling system, thereby dephosphorylating RXRalpha. In contrast, 9cRA failed to suppress phosphoErk 1/2 levels and subsequent RXRalpha phosphorylation. Although 9cRA also suppressed Ras activity, it simultaneously down-regulated mitogen-activated protein kinase phosphatase-1, an enzyme that inactivates Erk, thereby leaving the phosphorylation status of Erk unchanged. A combination of 9cRA (a potent ligand) and acyclic retinoid (a weak ligand preventing phosphorylation) resulted in a marked cooperation in transactivation via the RXR-response element and in inhibiting the proliferation of HuH7 cells. These events provide a novel molecular basis for the antitumor activity of acyclic retinoid against HCC.

Topics: Antineoplastic Agents; Blotting, Western; Carcinoma, Hepatocellular; Cell Cycle Proteins; Cell Division; Dual Specificity Phosphatase 1; Humans; Immediate-Early Proteins; Liver Neoplasms; Luciferases; MAP Kinase Signaling System; Mitogen-Activated Protein Kinases; Mutagenesis, Site-Directed; Phosphoprotein Phosphatases; Phosphorylation; Phosphoserine; Protein Phosphatase 1; Protein Tyrosine Phosphatases; ras Proteins; Receptors, Retinoic Acid; Response Elements; Retinoid X Receptors; Transcription Factors; Transcription, Genetic; Transcriptional Activation; Transfection; Tretinoin; Tumor Cells, Cultured

Acyclic retinoid (ACR), a novel synthetic retinoid, can prevent the recurrence of human hepatoma after surgical resection of primary tumors, but the molecular mechanisms by which ACR exerts antitumor effects are not known. In this study, we found that ACR inhibited the growth of three human hepatoma cell lines. In HepG2 cells, this inhibition was associated with an arrest of the cell cycle in G(0)-G(1), increased cellular levels of p21(CIP1), decreased levels of the hyperphosphorylated form of the retinoblastoma protein, and decreased levels of cyclin D1, but no significant changes were seen in the levels of the p16(INK4a), p27(KIP1), cyclin-dependent kinase 4, cyclin-dependent kinase 6, glycogen synthase kinase 3beta, or beta-catenin proteins. ACR also caused a decrease in the level of cyclin D1 mRNA. Cotreatment of HepG2 human hepatoma cells with the proteasome inhibitor N-acetyl-Leu-Leu-norleu-al did not prevent the ACR-induced decrease in cyclin D1 protein, in contrast to the protective effect of N-acetyl-Leu-Leu-norleu-al on the cyclin D1 protein in cells treated with all-trans-retinoic acid. In transient transfection reporter assays, ACR, but not all-trans-retinoic acid, inhibited transcription from the cyclin D1 promoter. As reported previously in colon carcinoma cells, we found that in hepatoma cells, cyclin D1 promoter activity is markedly stimulated by the beta-catenin/T-cell factor pathway. Nevertheless, even in the presence of excess beta-catenin, ACR markedly inhibited the transcriptional activity of the cyclin D1 promoter. This is the first systematic study of the inhibitory effects of ACR, or any other retinoid compound, on beta-catenin/T-cell factor-stimulated cyclin D1 promoter activity in human tumor cells. These novel effects of ACR provide further evidence that ACR may be a valuable agent in the chemoprevention and therapy of hepatoma and possibly other human malignancies.

Topics: Antineoplastic Agents; beta Catenin; Carcinoma, Hepatocellular; Cell Division; Cyclin D1; Cyclin-Dependent Kinase Inhibitor p21; Cyclins; Cytoskeletal Proteins; G1 Phase; Growth Inhibitors; Humans; Liver Neoplasms; Phosphorylation; Promoter Regions, Genetic; Retinoblastoma Protein; RNA, Messenger; Trans-Activators; Tretinoin; Tumor Cells, Cultured

Acyclic retinoid, a synthetic retinoid analog, as well as interferon alfa (IFN-alpha) and IFN-beta induce apoptosis in hepatocellular carcinoma (HCC) cells and are used clinically in the prevention of HCC. Here, we show that acyclic retinoid acts synergistically with IFNs in suppressing the growth and inducing apoptosis (as characterized by DNA fragmentation and chromatin condensation) in 5 human HCC cell lines (JHH7, HuH7, PLC/PRF/5, HLE, and HLF). This synergism was only observed when cells were pretreated with the acyclic retinoid, whereas natural retinoic acids (all-trans and 9-cis retinoic acid) were ineffective. This promotion may be due to up-regulation of type 1 IFN receptor (IFNR) expression by the retinoid. Accordingly, incubation with antitype 1 IFNR antibody abolished the synergy. Enhanced IFNR expression was accompanied by increased expression and DNA-binding activity of STAT1, an intracellular signal transducing molecule of IFNR, and increased induction of 2', 5'-oligoadenyl-5'-triphosphate synthetase, which is a target gene of STAT1. Acyclic retinoid did not have any effects on the growth of normal human hepatocytes (Hc) probably because of a lack of IFNR and STAT1 up-regulation. In conclusion, these results provide a rationale for combined biochemoprevention of HCC using acyclic retinoid and IFN-beta.

Topics: Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Carcinoma, Hepatocellular; DNA-Binding Proteins; Drug Synergism; Gene Expression; Humans; In Vitro Techniques; Interferon-beta; Liver Neoplasms; Receptors, Interferon; RNA, Messenger; STAT1 Transcription Factor; Trans-Activators; Tretinoin; Tumor Cells, Cultured; Up-Regulation

Acyclic retinoid (AR; all trans-3,7,11,15-tetramethyl-2,4,6,10,14-hexadecapentaenoic acid) prevented hepatocarcinogenesis in animal models and in a randomized clinical trial by eradicating premalignant and latent malignant clones of transformed cells from the liver. We investigated the possible mechanism of this clonal deletion at the cellular level.. Human hepatoma-derived cell lines, PLC/PRF/5, HuH-7, and JHH-7, were treated in vitro with AR. Secretion of albumin and that of lectin-reactive isoform of alpha-fetoprotein (AFP-L3) were measured as markers of differentiation and dedifferentiation of the cells, respectively. Telomerase reverse transcriptase (TERT) mRNA expression and telomerase activity were measured by reverse transcriptase polymerase chain reaction (RT-PCR) and stretch PCR assay, respectively. Caspase activities were measured by colorimetric protease assay. Mitochondrial membrane permeability transition was examined by Rhodamine staining.. Production of albumin was recovered while that of AFP-L3 was reduced after exposure of the cells to 10 microM AR for 2 days. This differentiation was maintained for another 2 days without retinoid. In parallel, both TERT mRNA expression and telomerase activity were down-regulated. The cells subsequently died due to apoptosis after 4-6 experimental days. Serial increases in mitochondrial membrane permeability and caspase-9 and -3 activities induced apoptosis.. AR first induces differentiation and reduces telomerase activity. Subsequent apoptosis may contribute to the eradication of the clone.

Topics: Alitretinoin; Antineoplastic Agents; Apoptosis; Carcinoma, Hepatocellular; Caspases; Cell Differentiation; Cell Membrane Permeability; DNA-Binding Proteins; Down-Regulation; Gene Expression Regulation, Enzymologic; Humans; Liver Neoplasms; Mitochondria; RNA, Messenger; Telomerase; Tretinoin; Tumor Cells, Cultured

We have shown previously that administration of acyclic retinoid to cirrhotic patients who had undergone curative treatment of preceding hepatocellular carcinoma (HCC) induced the disappearance of serum lectin-reactive alpha-fetoprotein (AFP-L3) and subsequently reduced the incidence of second liver cancers. AFP-L3 is a tumor marker that indicates the presence of occult tumors below the detection limit by diagnostic images. Therefore, we have proposed a new concept of 'clonal deletion' therapy with acyclic retinoid for the cancer chemoprevention against HCC. Such eradication of AFP-L3-producing latent malignant (or premalignant) cells from the liver suggested a new strategy to prevent HCC, which may be involved in the same category as cancer chemotherapy. In the present series of studies, we explored the molecular mechanism of 'clonal deletion' and found a novel mechanism of apoptosis induction by the retinoid. We have demonstrated a modification of a retinoid receptor, RXRalpha, by mitogen-activated protein (MAP) kinase-dependent phosphorylation, resulting in the loss of transactivating activity. This may lead HCC cells to be resistant to natural retinoic acid. However, acyclic retinoid restored the function of phosphorylated RXRalpha and induced its downstream pro-apoptotic genes including tissue transglutaminase, an enzyme that is implicated in apoptosis. Tissue transglutaminase-dependent apoptosis in HCC cells was independent of the activation of caspases. This novel mechanism of retinoid-induced apoptosis may give a clue to understand the molecular mechanism of clonal deletion.

Topics: Antineoplastic Agents; Apoptosis; Carcinoma, Hepatocellular; Chemoprevention; Clonal Deletion; Humans; Liver Neoplasms; Tretinoin

Many patients with liver cirrhosis are in a state of protein and energy malnutrition and require careful nutritional support. Our research has revealed that approximately 30% of the patients have protein-energy malnutrition, 40% protein malnutrition, and 10% energy malnutrition; 20% are in a normal nutritional state. Supplementation with branched-chain amino acids alleviates chronic liver failure, improves the protein nutritional state, and subsequently prolongs survival. In contrast, therapeutic modalities for energy malnutrition have not yet been fully elucidated and await further studies. Improved survival of the cirrhotic patients essentially brings a higher incidence of hepatocellular carcinoma (HCC). A synthetic analogue of vitamin A (acyclic retinoid or 4,5-dehydrogeranyl geranoic acid) prevents at least the development of second primary tumors after curative treatment of preceding HCC. The mechanism of this cancer chemo-prevention is clonal deletion of premalignant and latent malignant cells by the retinoid. We describe our clinical experiences with these two nutritional pharmacotherapies of chronic liver diseases and review their basic mechanisms.

Topics: Amino Acids, Branched-Chain; Antineoplastic Agents; Carcinoma, Hepatocellular; Cell Transformation, Neoplastic; Combined Modality Therapy; Humans; Liver Cirrhosis; Liver Failure; Liver Neoplasms; Nutritional Support; Protein-Energy Malnutrition; Randomized Controlled Trials as Topic; Survival Rate; Treatment Outcome; Tretinoin

Topics: Antineoplastic Agents; Carcinoma, Hepatocellular; Follow-Up Studies; Humans; Liver Neoplasms; Neoplasms, Second Primary; Survival Analysis; Tretinoin

Topics: Anticarcinogenic Agents; Carcinoma, Hepatocellular; Humans; Liver Neoplasms; Tretinoin

Synthetic 4,5-didehydro GGA (geranylgeranoic acid), a potent ligand both for cellular retinoic acid-binding protein and for nuclear retinoid receptors, induced apoptosis in human hepatoma-derived cell line HuH-7 but not in primary hepatocytes, although all-trans or 9-cis retinoic acid did not induce any growth inhibition. Either exogenous transforming growth factor-alpha (TGF alpha) or epidermal growth factor(EGF) prevented the cells from apoptosis in the presence of 4,5-didehydro GGA, but hepatocyte growth factor, insulin-like growth factor-II, insulin or triiodothyronine was essentially inactive. 4,5-Didehydro GGA down-regulated the cellular levels of TGF alpha mRNA as early as 30 min after the treatment. Either anti-TGF alpha or anti-EGF receptor monoclonal antibody induced apoptosis in HuH-7 cells without using the acid. Taken together, the present study strongly suggests that 4,5-didehydro GGA induced apoptosis in HuH-7 cells through the destruction of autocrine loop consisting of TGF alpha and EGF receptor, due to the down regulation of TGF alpha gene expression.

Topics: Animals; Apoptosis; Carcinoma, Hepatocellular; Cell Line; Cell Survival; Cells, Cultured; Epidermal Growth Factor; ErbB Receptors; Gene Expression Regulation; Humans; Insulin-Like Growth Factor II; Kinetics; Liver; Liver Neoplasms; Male; Mice; Mice, Inbred BALB C; Polymerase Chain Reaction; RNA, Messenger; Time Factors; Transforming Growth Factor alpha; Tretinoin; Triiodothyronine; Tumor Cells, Cultured

Topics: Carcinoma, Hepatocellular; Carrier State; Cell Transformation, Neoplastic; DNA, Viral; Hepatitis B virus; Humans; Liver Neoplasms; Neoplasm Recurrence, Local; Neoplasms, Second Primary; Retinoids; Tretinoin

Topics: Antineoplastic Agents; Carcinoma, Hepatocellular; Data Interpretation, Statistical; Diagnosis, Differential; Humans; Liver Neoplasms; Neoplasm Recurrence, Local; Neoplasms, Second Primary; Research Design; Tretinoin

Topics: Antineoplastic Agents; Carcinoma, Hepatocellular; Humans; Liver Neoplasms; Neoplasms, Second Primary; Tretinoin; Vitamin A; Vitamin A Deficiency

HuH-7 cells, a human hepatoma-derived cell line, underwent apoptosis in response to all-trans 3, 7, 11, 15-tetramethyl- 2, 4, 6, 10, 14-hexadecapentaenoic acid, or acyclic retinoid. The retinoid-induced apoptosis was verified by a characteristic step-wise fragmentation of genomic DNA and chromatin condensation. The induction of apoptosis was detected as early as 8 hrs after the addition of the retinoid and was concentration dependent (0.1-10 microM). Neither the natural retinoid all-trans retinoic acid nor 9-cis retinoic acid induced apoptosis. These data strongly indicate that the antitumor activity of the acyclic retinoid may be partly explained by the induction of apoptosis in tumor cells.

Topics: Apoptosis; Carcinoma, Hepatocellular; Cell Line; Chromatin; DNA Damage; DNA, Neoplasm; Dose-Response Relationship, Drug; Humans; Kinetics; Liver Neoplasms; Time Factors; Tretinoin; Tumor Cells, Cultured

We investigated the effects of polyprenoic acid, E5166, on the production and secretion of alpha-fetoprotein (AFP) and on cell kinetics in a human hepatoma cell line (HuH-7). The cellular AFP content, measured flow cytometrically for cells stained by an indirect immunofluorescence method, was decreased by treatment with E5166. AFP in the culture medium decreased exponentially during exposure of cells to the drug. These changes were dose-dependent. The growth of HuH-7 cells in vitro was clearly suppressed in the presence of E5166. The inhibition of growth depended on the concentration of the agent. The fraction of S phase cells decreased relatively in the cells treated with a high concentration of the drug, whereas it increased in the cells treated with lower doses.

Topics: alpha-Fetoproteins; Carcinoma, Hepatocellular; Cell Cycle; Cell Differentiation; Cells, Cultured; Dose-Response Relationship, Drug; Flow Cytometry; Gene Expression Regulation; Humans; Liver Neoplasms; Tretinoin