Hexige Saiyin

Aurora C is directly associated with Survivin and required for cytokinesis

Much recent attention has been focused on Aurora C, the third member of the mammalian Aurora kinases family that plays significant roles in mitosis. We report here that using sensitive RT‐PCR to amplify the C‐terminal, we found that Aurora C is not only expressed highly in testis, but also among 16 other human tissues in a broad‐spectrum way. Aurora C, as a chromosomal passenger protein, is co‐localized with Aurora B and Survivin in mitotic cells. Aurora C can also be associated with Aurora B and Survivin in vivo and directly binds to Survivin but not Aurora B in vitro. Over‐expression of a catalytically inactive mutant of Aurora C impaired the localization of Aurora C to the spindle midzone and severely disturbed the cytokinesis, resulting in multinucleation, all of which are consistent with the results induced by the mutant of Aurora B. Furthermore, we provide evidence that Aurora C could rescue the multinucleate phenotype produced by Aurora B mutant, and vice versa. Overall, these findings demonstrate that Aurora C, a member of the chromosomal passenger complex, is required for cytokinesis.

A New and General Fabrication of an Aligned Carbon Nanotube/Polymer Film for Electrode Applications

High-temperature or vacuum processes are typically required to fabricate them, resulting in high costs. These electrode materials have been also shown to be unstable in many conditions, e.g., platinum may be dissolved in corrosive electrolytes and indium tin oxide is fragile and not resistant to acid. [ 4–6 ] In addition, there are limited sources for either platinum or indium. These disadvantages have largely hindered their practical applications in a wide variety of fi elds. Therefore, it is highly desired to develop new electrode materials with good stability, high effi ciency, and low cost. Recently, increasing interest has been paid to carbon nanotube (CNT)/poly mer composite fi lms, which may represent a family of promising electrode materials to simultaneously solve the above challenges due to incorporated excellent properties from CNTs and polymers. CNTs exhibit high mechanical strength and electrical conductivity, while polymers provide good fl exibility, high transparency, easy processing, and low cost. [ 7 , 8 ] CNT/polymer fi lms have been typically fabricated by dispersing two moieties in solvent, followed by spin coating or other solution processes. [ 9 ] Although it is easy to operate with relatively high effi ciency, random dispersion of CNTs in polymer matrices greatly decreases the physical properties of resulting composite fi lms. [ 10 ] For instance, electrical conductivities of CNT/polymer fi lms at room temperature are often less than 10 − 3 S cm − 1 , which largely reduces their electrode applications. In order to improve their electrical conductivities, aligned CNT/polymer fi lms by using CNT sheets as templates have been recently realized, and conductivities up to 10 2 S cm − 1

Isolation and functional analysis of human HMBOX1, a homeobox containing protein with transcriptional repressor activity.

We have identified and isolated a novel human gene, HMBOX1 (homeobox containing 1) from a pancreatic cDNA library. Human HMBOX1 is widely expressed in 18 tissues, and it is highly expressed in pancreas. According to the genome database, HMBOX1 is located at the boundary of 8p12.3 and 8p21.1. HMBOX1 proteins are highly conserved in human, mouse, rat, chicken and Xenopus laevis. A phylogenetic tree shows that HMBOX1 may represent a distinct group in HNF (Hepatocyte Nuclear Factor) transcriptional factors. Functional HMBOX1::EGFP (enhanced green fluorescent protein) fusion protein revealed that HMBOX1 accumulated more in cytoplasm than in nucleus. Co-transfection of HEK-293T cells with pM-HMBOX1 plasmid and reporter plasmid pGAL45tkLUC indicates that HMBOX1 is a transcription repressor. In situ hybridization on paraffin sections of mouse tissues demonstrated that Hmbox1 is widely expressed in pancreas and the expression of this gene can also be detected in pallium, hippocampus and hypothalamus.

Cyclophilin A promotes human hepatocellular carcinoma cell metastasis via regulation of MMP3 and MMP9.

Cyclophilin A (CypA) is a member of peptidyl prolyl isomerases (PPIases), which catalyze the cis/trans isomerization of prolyl peptide bonds on the NH-terminal side of Pro residues in peptide chains. Altered expression of CypA has been reported in hepatocellular carcinoma (HCC), but the biological functions of CypA in HCC remain unknown. We found that the level of CypA expression correlated with the metastatic capability of two HCC cell lines, MHCC97-L and MHCC97-H. Stable expression of ectopic CypA in SK-Hep1 cells promotes cell adhesion, motility, chemotaxis, and in vivo lung metastasis, without affecting cell proliferation. We further analyzed microarray results to identify target genes controlled by CypA. Twenty-one genes related to metastasis were altered by CypA over-expression. A member of matrix metalloproteinase, MMP3, was identified by microarray analysis. The regulation of MMP3 and its homologue MMP9 by CypA were further confirmed by quantitative real-time RT-PCR and zymography assay. Taken together, our data suggest that CypA promotes HCC cell metastasis at least partially through up-regulation of MMP3 and MMP9.

Metallothionein MT1M is a tumor suppressor of human hepatocellular carcinomas.

Members of the metallothionein (MT) family are short, cysteine-rich proteins involved in metal metabolism and detoxification, suggesting that MT proteins protect cells from damage caused by electrophilic carcinogens and thereby constitute a critical surveillance system against carcinogenesis. However, the roles of MT proteins in human hepatocellular carcinoma (HCC) are not fully understood. We identified a member of the MT family, termed MT1M. MT1M is expressed in various normal tissues with the highest level in the liver. MT1M expression can be induced by heavy metals and protect Escherichia coli from heavy metal toxicity. However, MT1M expression markedly decreased in human HCC specimens. A methylation profiling analysis indicated that the MT1M promoter is methylated in the majority of HCC tumors examined. Moreover, restored expression of MT1M in the HCC cell line Hep3B, which lacks endogenous MT1M expression, suppressed cell growth in vitro and in vivo and augmented apoptosis induced by tumor necrosis factor α. Furthermore, stable expression of MT1M in Hep3B cells blocked tumor necrosis factor α-induced degradation of IκBα and transactivation of NF-κB. We conclude that MT1M is a novel member of the MT family. Frequent downregulation of MT1M in human HCC may contribute to liver tumorigenesis by increasing cellular NF-κB activity.

Oligo-microarray analysis reveals the role of cyclophilin A in drug resistance

Cyclophilin A (CYPA) belongs to peptidyl prolyl isomerases (PPIases), which catalyze the cis/trans isomerization of prolyl peptide bonds in cellular communication. CYPA has been implicated in several pathological processes, including cancer, inflammatory diseases, and HIV-1 infection. Up-regulation of CYPA has been found to be a common phenomenon in several tumor types, including in hepatocellular carcinoma (HCC). However, the role of CYPA in tumor cells remains unknown. We generated a stable SK-Hep1 cell line and studied the CYPA regulated genes at the transcriptome level. The microarray results reveal that CYPA can up-regulate the expression of many cytokine and drug resistance related genes. Furthermore, we showed that the elevated CYPA expression contributes to drug resistance. We postulate that the over-expression of CYPA in tumors may play a role in clinical resistance to chemotherapy.

Genetic Variants in Five Novel Loci Including CFB and CD40 Predispose to Chronic Hepatitis B

Hepatitis B virus affects more than 2 billion people worldwide, 350 million of which have developed chronic hepatitis B (CHB). The genetic factors that confer CHB risk are still largely unknown. We sought to identify genetic variants for CHB susceptibility in the Chinese population. We undertook a genome‐wide association study (GWAS) in 2,514 CHB cases and 1,130 normal controls from eastern China. We replicated 33 of the most promising signals and eight previously reported CHB risk loci through a two‐stage validation totaling 6,600 CHB cases and 8,127 controls in four independent populations, of which two populations were recruited from eastern China, one from northern China and one from southern China. The joint analyses of 9,114 CHB cases and 9,257 controls revealed significant association of CHB risk with five novel loci. Four loci are located in the human leukocyte antigen (HLA) region at 6p21.3, including two nonsynonymous variants (rs12614 [R32W] in complement factor B [CFB], Pmeta=1.28 × 10−34; and rs422951 [T320A] in NOTCH4, Pmeta = 5.33 × 10−16); one synonymous variant (rs378352 in HLA‐DOA corresponding to HLA‐DOA*010101, Pmeta = 1.04 × 10−23); and one noncoding variant (rs2853953 near HLA‐C, Pmeta = 5.06 × 10−20). Another locus is located at 20q13.1 (rs1883832 in the Kozak sequence of CD40, Pmeta = 2.95 × 10−15). Additionally, we validated seven of eight previously reported CHB susceptibility loci (rs3130542 at HLA‐C, rs1419881 at TCF19, rs652888 at EHMT2, rs2856718 at HLA‐DQB1, rs7453920 at HLA‐DQB2, rs3077 at HLA‐DPA1, and rs9277535 at HLA‐DPA2, which are all located in the HLA region, 9.84 × 10−71 ≤ Pmeta ≤ 9.92 × 10−7). Conclusion: Our GWAS identified five novel susceptibility loci for CHB. These findings improve the understanding of CHB etiology and may provide new targets for prevention and treatment of this disease. (Hepatology 2015;62:118‐128)

Breast Cancer Metastasis Suppressor 1 Regulates Hepatocellular Carcinoma Cell Apoptosis via Suppressing Osteopontin Expression

Breast cancer metastasis suppressor 1 (BRMS1) was originally identified as an active metastasis suppressor in human breast cancer. Loss of BRMS1 expression correlates with tumor progression, and BRMS1 suppresses several steps required for tumor metastasis. However, the role of BRMS1 in hepatocellular carcinoma (HCC) remains elusive. In this study, we found that the expression level of BRMS1 was significantly down-regulated in HCC tissues. Expression of BRMS1 in SK-Hep1 cells did not affect cell growth under normal culture conditions, but sensitized cells to apoptosis induced by serum deprivation or anoikis. Consistently, knockdown of endogenous BRMS1 expression in Hep3B cells suppressed cell apoptosis. We identified that BRMS1 suppresses osteopontin (OPN) expression in HCC cells and that there is a negative correlation between BRMS1 and OPN mRNA expression in HCC tissues. Moreover, knockdown of endogenous OPN expression reversed the anti-apoptosis effect achieved by knockdown of BRMS1. Taken together, our results show that BRMS1 sensitizes HCC cells to apoptosis through suppressing OPN expression, suggesting a potential role of BRMS1 in regulating HCC apoptosis and metastasis.

Zinc finger transcription factor 191, directly binding to β‐catenin promoter, promotes cell proliferation of hepatocellular carcinoma

Activation of β‐catenin, the central effector of the canonical wingless‐type (Wnt) pathway, has been implicated in hepatocellular carcinoma (HCC). However, the transcription regulation mechanism of the β‐catenin gene in HCC remains unknown. Here we report that human zinc finger protein 191 (ZNF191) is a potential regulator of β‐catenin transcription. ZNF191, a Krüppel‐like protein, specifically interacts with the TCAT motif, which constitutes the HUMTH01 microsatellite in the tyrosine hydroxylase (TH) gene ex vivo. We demonstrate that ZNF191 is significantly overexpressed in human HCC specimens and is associated with growth of human HCC cells. Global profiling of gene expression in ZNF191 knockdown human hepatic L02 cells revealed that the important Wnt signal pathway genes β‐catenin and cyclin D1 messenger RNAs (mRNAs) are significantly down‐regulated. In agreement with transcription level, β‐catenin and cyclin D1 proteins are also down‐regulated in transient and stable ZNF191 knockdown L02 and hepatoma Hep3B cell lines. Moreover, significant correlation between ZNF191 and β‐catenin mRNA expression was detected in human HCCs. Promoter luciferase assay indicated that ZNF191 can increase transcription activity of the full‐length β‐catenin (CTNNB1) promoter, and nucleotide (nt)‐1407/‐907 of the CTNNB1 promoter exhibited the maximum transcriptional activity. Electrophoretic mobility shift assay showed that purified ZNF191 protein can directly bind to the CTNNB1 promoter, and the binding region is located at nt‐1254/‐1224. Finally, we demonstrate that the key binding sequence of ZNF191 in vivo is ATTAATT. Conclusion: ZNF191 can directly bind to the CTNNB1 promoter and activate the expression of β‐catenin and its downstream target genes such as cyclin D1 in hepatoma cell lines. This study uncovers a new molecular mechanism of transcription regulation of the β‐catenin gene in HCC. (HEPATOLOGY 2012;55:1830–1839)

Proapoptotic Function of Integrin β3 in Human Hepatocellular Carcinoma Cells

Purpose: This study evaluates the proapoptotic function of integrin β3 in human hepatocellular carcinoma (HCC). Experimental Design: The expression of integrin β3 in 67 HCC specimens paired with corresponding neighboring nontumorous tissue was studied by quantitative real-time PCR and Western blot. The proapoptotic function of integrin β3 in SMMC-7721 human hepatoma cells overexpressing ITGB3 (gene coding integrin β3) was determined through colony formation, serum starvation, and anoikis assay. Results: Compared with neighboring pathologically normal liver tissue, ∼60% of the HCC specimens showed a significant down-regulated level of integrin β3 expression. Transient expression of integrin β3 in SMMC-7721 resulted in an enhanced level of apoptosis and suppression of colony formation. Cell growth inhibition on serum/ligand deprivation and incidences of anoikis were remarkably increased in SMMC-7721 with stable expression of integrin β3 in comparison with vector control transfectants. In addition, expression of fibrinogen and vitronectin, two native ligands for integrin αvβ3 in liver, was inhibited, which was correlated with the decreased integrin β3 expression. Replenishing these ligands to the starved SMMC-7721 stable transfectants effectively restored the proapoptotic function of integrin β3. Conclusions: Down-regulation of integrin β3 and its ligands in liver is related to the aggressive growth of HCC. Thus, reconstitution of integrin β3 in HCC may be a potential therapeutic approach to inhibit aggressive growth of liver cancer.