Decreased expression of acetyl‐CoA synthase 2 promotes metastasis and predicts poor prognosis in hepatocellular carcinoma

Metastasis is a serious risk that may occur during the treatment of hepatocellular carcinoma (HCC), preventing many patients from being surgical candidates and contributing to poor prognosis. Hypoxia has been proved an important factor of metastasis through the epithelial–mesenchymal transition (EMT) pathway. Acetyl‐CoA synthase 2 (ACSS2) provides an acetyl group for the acetylation of hypoxia‐inducible factor (HIF)‐2α, and this epigenetic modification affects the activity of HIF‐2α and the subsequent EMT process. Here, we showed that ACSS2 expression was negatively correlated with HCC malignancy. Knockdown of ACSS2 increased the invasion and migration ability of HCC cells and promoted EMT without increasing the total protein level of HIF‐2α, even in hypoxic conditions. The immunoprecipitation assay revealed downregulated acetylation levels of HIF‐2α after ACSS2 knockdown in hypoxic conditions, which resulted in enhanced HIF‐2α activity. Finally, decreased expression of ACSS2 was found to be related to advanced stage and poor overall survival and disease‐free survival rates in a cohort of patients with HCC. In conclusion, ACSS2 plays an important role in the acetylation process of HIF‐2α, which effectively modifies the activity of HIF‐2α under hypoxic conditions and greatly impacts on the prognosis of patients with HCC.     

TGF‐β inactivation and TGF‐α overexpression cooperate in an in vivo mouse model to induce hepatocellular carcinoma that recapitulates molecular features of human liver cancer

Hepatocellular carcinoma (HCC) results from the cumulative effects of deregulated tumor suppressor genes and oncogenes. The tumor suppressor and oncogenes commonly affected include growth factors, receptors and their downstream signaling pathway components. The overexpression of transforming growth factor alpha (TGF‐α) and the inhibition of TGF‐β signaling are especially common in human liver cancer. Thus, we assessed whether TGF‐α overexpression and TGF‐β signaling inactivation cooperate in hepatocarcinogenesis using an in vivo mouse model, MT1/TGFa;AlbCre/Tgfbr2^flx/flx mice (“TGFa;Tgfbr2^hepko”), which overexpresses TGF‐α and lacks a TGF‐β receptor in the liver. TGF‐β signaling inactivation did not alter the frequency or number of cancers in mice with overexpression of TGF‐α. However, the tumors in the TGFa;Tgfbr2^hepko mice displayed increased proliferation and increased cdk2, cyclin E and cyclin A expression as well as decreased Cdkn1a/p21 expression compared to normal liver and compared to the cancers arising in the TGF‐α overexpressing mice with intact TGF‐β receptors. Increased phosphorylated ERK1/2 expression was also present in the tumors from the TGFa;Tgfbr2^hepko mice and correlated with downregulated Raf kinase inhibitor protein expression, which is a common molecular event in human HCC. Thus, TGF‐β signaling inactivation appears to cooperate with TGF‐α in vivo to promote the formation of liver cancer that recapitulates molecular features of human HCC.     

Time‐dependent changes in proliferation,DNA damage and clock gene expression in hepatocellular carcinoma and healthy liver of a transgenic mouse model

Hepatocellular carcinoma (HCC) is highly resistant to anticancer therapy and novel therapeutic strategies are needed. Chronotherapy may become a promising approach because it may improve the efficacy of antimitotic radiation and chemotherapy by considering timing of treatment. To date little is known about time‐of‐day dependent changes of proliferation and DNA damage in HCC. Using transgenic c‐myc/transforming growth factor (TGFα) mice as HCC animal model, we immunohistochemically demonstrated Ki67 as marker for proliferation and γ‐H2AX as marker for DNA damage in HCC and surrounding healthy liver (HL). Core clock genes (Per1, Per2, Cry1, Cry2, Bmal 1, Rev‐erbα and Clock) were examined by qPCR. Data were obtained from samples collected ex vivo at four different time points and from organotypic slice cultures (OSC). Significant differences were found between HCC and HL. In HCC, the number of Ki67 immunoreactive cells showed two peaks (ex vivo: ZT06 middle of day and ZT18 middle of night; OSC: CT04 and CT16). In ex vivo samples, the number of γ‐H2AX positive cells in HCC peaked at ZT18 (middle of the night), while in OSC their number remained high during subjective day and night. In both HCC and HL, clock gene expression showed a time‐of‐day dependent expression ex vivo but no changes in OSC. The expression of Per2 and Cry1 was significantly lower in HCC than in HL. Our data support the concept of chronotherapy of HCC. OSC may become useful to test novel cancer therapies.     

Multicenter analysis of soluble Axl reveals diagnostic value for very early stage hepatocellular carcinoma

If diagnosed at early stages, patients with hepatocellular carcinoma (HCC) can receive curative therapies, whereas therapeutic options at later stages are very limited. Here, we addressed the potential of soluble Axl (sAxl) as a biomarker of early HCC by analyzing levels of sAxl in 311 HCC and 237 control serum samples from centers in Europe and China. Serum concentrations of sAxl were significantly increased in HCC (18.575 ng/mL) as compared to healthy (13.388 ng/mL) or cirrhotic (12.169 ng/mL) controls. Receiver operating characteristic curve analysis of sAxl in very early stage HCC patients (BCLC 0) showed an area under the curve (AUC) of 0.848, with a sensitivity of 76.9% and a specificity of 69.2%. α‐Fetoprotein (AFP)‐negative HCC patients displayed an AUC of 0.803, with sensitivity and specificity of 73% and 70.8%. Combination of sAxl and AFP improved diagnostic accuracy to 0.936 in very early HCC patients and to 0.937 in all HCC. Differential diagnosis of very early HCC versus liver cirrhosis showed a combined performance for sAxl and AFP of 0.901 with a sensitivity of 88.5% and a specificity of 76.7%. Furthermore, sAxl levels failed to be elevated in primary ovarian, colorectal and breast carcinomas as well as in secondary hepatic malignancies derived from colon. In summary, sAxl outperforms AFP in detecting very early HCC as compared to healthy or cirrhotic controls and shows high diagnostic accuracy for AFP‐negative patients. sAxl is specific for HCC and suggested as a biomarker for routine clinical use.     

ROS signaling by NADPH oxidase 5 modulates the proliferation and survival of prostate carcinoma cells

Prostate cancer (PCa) is the most commonly diagnosed cancer and second leading cause of male cancer death in Western nations. Thus, new treatment modalities are urgently needed. Elevated production of reactive oxygen species (ROS) by NADPH oxidase (Nox) enzymes is implicated in tumorigenesis of the prostate and other tissues. However, the identity of the Nox enzyme(s) involved in prostate carcinogenesis remains largely unknown. Analysis of radical prostatectomy tissue samples and benign and malignant prostate epithelial cell lines identified Nox5 as an abundantly expressed Nox isoform. Consistently, immunohistochemical staining of a human PCa tissue microarray revealed distinct Nox5 expression in epithelial cells of benign and malignant prostatic glands. shRNA‐mediated knockdown of Nox5 impaired proliferation of Nox5‐expressing (PC‐3, LNCaP) but not Nox5‐negative (DU145) PCa cell lines. Similar effects were observed upon ROS ablation via the antioxidant N‐acetylcysteine confirming ROS as the mediators. In addition, Nox5 silencing increased apoptosis of PC‐3 cells. Concomitantly, protein kinase C zeta (PKCζ) protein levels and c‐Jun N‐terminal kinase (JNK) phosphorylation were reduced. Moreover, the effect of Nox5 knockdown on PC‐3 cell proliferation could be mimicked by pharmacological inhibition of JNK. Collectively, these data indicate that Nox5 is expressed at functionally relevant levels in the human prostate and clinical PCa. Moreover, findings herein suggest that Nox5‐derived ROS and subsequent depletion of PKCζ and JNK inactivation play a critical role in modulating intracellular signaling cascades involved in the proliferation and survival of PCa cells. © 2014 The Authors. Molecular Carcinogenesis published by Wiley Periodicals, Inc.     

Association of JNK1 with p21waf1 and p53: modulation of JNK1 activity

Exposure of mammalian cells to genotoxic stress results in activation of the c-jun amino-terminal kinase (JNK)-stress-activated protein kinase (SAPK) pathway and induction of DNA repair enzymes and cell cycle-regulatory proteins such as p53 and p21waf1. The p53 tumor suppressor protein transmits signals that activate p21waf1 gene expression. The p21waf1 protein then restricts cell-cycle progression, thereby allowing time for DNA repair to occur. In this study, we investigated the effects of modulation of the level of wild-type and mutant p53 protein on basal JNK1 activity in the A1-5 rat fibroblast cell line. This cell line contains a p53 gene coding for a temperature-sensitive p53 protein, which allows us to regulate the relative level of wild-type and mutant p53 protein produced in cells. Using the immune complex kinase assay to measure JNK1 activity, we demonstrated that cells expressing the wild-type-conformation p53 protein (when grown at 32.5 degrees C) exhibited a very low level of JNK1 activity. When cells were grown at 37 degrees C or 39 degrees C to express predominantly mutant p53 protein, basal level of JNK1 activity was significantly higher than at 32.5 degrees C. We also demonstrated protein-protein interactions between the p53, p21waf1, and JNK1 proteins in this cell line. Both wild-type p53 protein (expressed at 32.5 degrees C) and mutant p53(val135) protein (expressed at 37 degrees C and 39 degrees C) were present in immunocomplexes of JNK1 protein. Under conditions where wild-type p53 protein was present to induce p21waf1 expression (at 32.5 degrees C), a higher level of p21waf1 protein was also detected in the JNK1 immunocomplexes than in those at 37 degrees C and 39 degrees C. We next investigated the effect that co-association of p53 protein and p21waf1 protein would have on JNK1 activity. We measured basal levels of JNK1 activity in cells expressing wild-type p53 and p21waf1, or in p21waf1-null cells, and demonstrated that cells expressing both p53 and p21waf1 proteins exhibited an approximately threefold lower basal level of JNK1 activity when compared with p21waf1-null cells. To confirm that p21waf1 protein expression in cells resulted in reduced JNK1 activity, we transfected p21waf1-/- cells with a p21waf1 expression vector. We observed that JNK1 activity was inhibited after exogenous p21waf1 protein was expressed in these cells. Our results provide evidence for modulation of the JNK1 pathway by p53 and p21waf1 proteins and support the hypothesis that modulation of JNK1 activity occurred through protein-protein interactions between JNK1, p53, and p21waf1 proteins.     

JIP影响鼻咽癌细胞增殖和凋亡的生物学效应研究

背景与目的：研究表明LMP1激活c-Jun N末端激酶（c-Jun N-ternimal kinase,JNK)介导的信号途径在促进鼻咽癌的发生发展有重要作用,并且发现JNK相互作用蛋白（JNK interacting protein,JIP)在鼻咽癌细胞中能够有效抑制JNK信号途径。本实验在此基础上进一步研究JIP对鼻咽癌细胞增殖和凋亡生物学效应的影响。方法：采用MTT法观察不同剂量的JIP及相同剂量JIP作用不同时间后鼻咽癌细胞生长情况;并用集落形成率确定单个鼻咽癌细胞的增殖能力;同时用流式细胞术分析JIP作用不同时间后鼻咽癌细胞生长情况;并用集落形成率确定单个鼻咽癌细胞的增殖能力;同时用流式细胞术分析JIP作用前后细胞周期时相的变化;最后通过流式细胞术检测JIP作用后鼻咽癌细胞凋亡百分率的改变。结果：（1）随着转染JIP量的增加,细胞的存活率逐渐下降,存在剂量依赖效应;1μg/ml JIP作用24、48、72h后,细胞存活率分别为77．8％、59．2％、61．8％。（2）转染JIP后鼻咽癌细胞形成的集落明显减少,且集落体积变小。（3）转染JIP使鼻咽癌细胞周期G0／G1期细胞百分率由66．24％上升到71．89％,S期细胞百分率由25．87％下降到19．96％。（4）与对照组相比,转染JIP后细胞的24h 凋亡百分率由1．25％上升到8．25％,上升约6．6倍,48h由1．04％上升到31．45％,上升约30倍。结论：JIP能够有效抑制鼻咽癌细胞生长增殖,引起鼻咽癌细胞周期G1／S期延长,并明显促进鼻咽癌细胞凋亡,提示JIP是治疗鼻咽癌潜在的分子药物。     

Modulation of TGF‐β activity by latent TGF‐β‐binding protein 1 in human malignant glioma cells

High biological activity of the transforming growth factor (TGF)‐β‐Smad pathway characterizes the malignant phenotype of malignant gliomas and confers poor prognosis to glioma patients. Accordingly, TGF‐β has become a novel target for the experimental treatment of these tumors. TGF‐β is processed by furin‐like proteases (FLP) and secreted from cells in a latent complex with its processed propeptide, the latency‐associated peptide (LAP). Latent TGF‐β‐binding protein 1 (LTBP‐1) covalently binds to this small latent TGF‐β complex (SLC) and regulates its function, presumably via interaction with the extracellular matrix (ECM). We report here that the levels of LTBP‐1 protein in vivo increase with the grade of malignancy in gliomas. LTBP‐1 is associated with the ECM as well as secreted into the medium in cultured malignant glioma cells. The release of LTBP‐1 into the medium is decreased by the inhibition of FLP activity. Gene‐transfer mediated overexpression of LTBP‐1 in glioma cell lines results in an increase inTGF‐β activity. Accordingly, Smad2 phosphorylation as an intracellular marker of TGF‐β activity is enhanced. Conversely, LTBP‐1 gene silencing reduces TGF‐β activity and Smad2 phosphorylation without affecting TGF‐β protein levels. Collectively, we identify LTBP‐1 as an important modulator of TGF‐β activation in glioma cells, which may contribute to the malignant phenotype of these tumors. © 2009 UICC     

A novel AMPK activator shows therapeutic potential in hepatocellular carcinoma by suppressing HIF1α‐mediated aerobic glycolysis

Hepatocellular carcinoma (HCC) is characterized by rapid growth, early vascular invasion, and high metastasis. Currently available US Food and Drug Administration (FDA)‐approved drugs show low therapeutic efficacy, limiting HCC treatment to chemotherapy. We designed and synthesized a novel small molecule, SCT‐1015, that allosterically activated adenosine monophosphate‐activated protein kinase (AMPK) to suppress the aerobic glycolysis in HCC. SCT‐1015 was shown to bind the AMPK α and β‐subunit interface, thereby exposing the kinase α domain to the upstream kinases, resulting in the increased AMPK activity. SCT‐1015 dramatically reduced HCC cell growth in vitro and tumor growth in vivo. We further found that AMPK formed protein complexes with hypoxia‐inducible factor 1‐alpha (HIF1α) and that SCT‐1015‐activated AMPK promoted hydroxylation of HIF1α (402P and 564P), resulting in HIF1α degradation by the ubiquitin‐proteasome system. With declined HIF1α abundance, many glycolysis‐related enzymes were downregulated, suppressing aerobic glycolysis, and promoting oxidative phosphorylation. These results indicated that SCT‐1015 channeled HCC cells into an unfavorable metabolic status. Overall, we reported SCT‐1015 as a direct activator of AMPK signaling that held therapeutic potential in HCC.     

肿瘤相关粘蛋白 MUC1 和抑癌基因 p53 在原发性肝癌中的表达

目的：通过测定MUC1和p53在肝脏不同组织中的表达差异，探讨MUC1和p53在肿瘤诊断和免疫治疗中的意义。方法：采用免疫组化方法检测35例肝癌（28例肝细胞癌，7例胆管细胞癌），8例肝硬化，8例肝血管瘤和10例正常肝组织中MUC1和p53的表达。结果：MUC1和p53基因均阳性表达于肝癌组织，它们在肝癌组织中的阳性表达率明显高于其它肝脏组织（P〈0．01），MUC1主要表达于细胞膜，其表达与肝癌的病理分型和组织学分化无相关性（P〉0．05），但肝癌伴有门静脉癌栓组与不伴有门静脉癌栓组之间MUC1表达率具有显著差异性（P〈0．05）；p53表达于细胞核，在Ⅰ、Ⅱ、Ⅲ级肝癌组织中的表达呈现递增趋势。结论：p53与肝癌的发生发展密切相关，MUC1在肝癌组织中的表达与分布特点可以作为肝癌诊断、判断预后的指标，同时，MUC1作为一种靶抗原，为今后的肝癌免疫治疗提供新的线索。     

Roles of ezrin in the growth and invasiveness of esophageal squamous carcinoma cells

Ezrin, which crosslinks the cytoskeleton and plasma membrane, is involved in the growth and metastatic potential of cancer cells. Ezrin expression in esophageal squamous cell carcinoma (ESCC) was described recently, but its roles and the underlying mechanism(s) remain unclear. In our study, we first showed that ezrin in ESCC cell is expressed in the nucleus as well as in the cytoplasm and plasma membrane. Then, by using RNAi, we revealed that interference of ezrin expression suppressed the growth, adhesion and invasiveness of ESCC cells. Tumorigenesis experiments revealed that ezrin may directly regulate tumor formation in vivo. To explore the molecular mechanisms through which ezrin contributes to the proliferation and invasiveness of ESCC cells, we used cDNA microarrays to analyze ezrin knockdown cells and the control cells; of 39,000 genes examined, 297 were differentially expressed upon ezrin knockdown, including some proliferation‐ and invasiveness‐related genes such as ATF3, CTGF and CYR61. Furthermore, pathway analysis showed that ezrin knockdown led to decreased activation of the TGF‐β and MAPK pathways, and ezrin‐mediated cell invasiveness alteration was dependent on the activation of these pathways. Finally, immunohistochemical staining on 80 ESCC specimens and 50 normal esophageal mucosae revealed that the expression levels of 3 altered genes involved in the regulation of cell proliferation and tumor metastasis, including CTGF, CYR61 and ATF3, were altered in ESCCs, and their expression pattern correlated with ezrin expression. Taken together, we propose that ezrin might function in the growth and invasiveness of ESCC cells through the MAPK and TGF‐β pathways. © 2008 Wiley‐Liss, Inc.     

18β‐glycyrrhetinic acid inhibits hepatocellular carcinoma development by reversing hepatic stellate cell‐mediated immunosuppression in mice

Hepatic stellate cells (HSCs) have immunosuppressive capabilities and contribute to the occurrence and development of hepatocellular carcinoma (HCC). Thus, activated HSCs may be a suitable target for HCC therapy. Our study used mixed leukocyte reactions (MLR) in vitro to demonstrate that 18β‐glycyrrhetinic acid (GA) could reverse HSC‐mediated immunosuppression by reducing T‐cell apoptosis and regulatory T (Treg) cells expression, thereby enhancing the ability of T cells to attack tumor cells and attenuating HCC cell invasiveness. Moreover, we established a HCC orthotopic implantation model in immunocompetent C57BL/6 mice, which suggested that GA played a protective role in HCC development by reducing immunosuppression mediated by HSCs in the tumor microenvironment.     

Identification of integrins α6 and β7 as c‐Jun‐ and transformation‐relevant genes in highly invasive fibrosarcoma cells

Understanding the mechanisms of tumor cell invasion is essential for our attempts to prevent cancer deaths. We screened by DNAmicroarrays the c‐Jun‐ and transformation‐related gene expression changes in S‐adenosylmethionine decarboxylase (AdoMetDC)‐overexpressing mouse fibroblasts that are highly invasive in vivo, and their derivatives expressing a tetracycline‐inducible dominant‐negative mutant of c‐Jun (TAM67) or c‐Jun shRNA. Among the small set of target genes detected were integrins α6 and β7, cathepsin L and thymosin β4, all upregulated in the AdoMetDC‐transformed cells and downregulated upon reversal of transformation by TAM67 or c‐Jun shRNA. The upregulation of integrin α6 subunit, pairing with integrin β1, endowed the transformed cells with the capability to attach to basement membrane laminin and to spread. Further, inhibition of integrin α6 or β1 function with neutralizing antibodies blocked the invasiveness of AdoMetDC‐transformants and human HT‐1080 fibrosarcoma cells in three‐dimensional Matrigel. Moreover, immunohistochemical analyses showed strong integrin α6 staining in high‐grade human fibrosarcomas. Our data show that c‐Jun can regulate all three key steps of invasion: cell adhesion (integrin α6), basement membrane/extracellular matrix degradation (cathepsin L) and cell migration (thymosin β4). In addition, this is the first study to associate integrin β7, known as a leukocyte‐specific integrin binding to endothelial/epithelial cell adhesion molecules, with the transformed phenotype in cells of nonleukocyte origin. As tumor cell invasion is a prerequisite for metastasis, the observed critical role of integrin α6β1 in fibrosarcoma cell invasion/spreading allures testing antagonists to integrin α6β1, alone or combined with inhibitors of cathepsin L and thymosin β4, as chemotherapeutic agents. © 2009 UICC