Folic acid conjugated mPEG-PEI600 as an efficient non-viral vector for targeted nucleic acid delivery.

In this study we describe a novel polymer, mPPS-FA, synthesized as a potential gene transfer vector. To complete mPPS-FA, folic acid was conjugated to a backbone (named mPPS) consisting of a copolymer of methyl PEG-2000, PEI-600, and sebacoyl chloride. (1)H NMR, FT-IR, and UV spectroscopy were used to characterize the structure of mPPS-FA. It was revealed that mPPS-FA holds the ability to bind plasmid DNA yielding positively charged particles (polyplexes). Dynamic light scattering (DLS) and TEM techniques were used to study the size and morphology of the formed mPPS-FA/DNA nanocomplexes. The mPPS-FA/DNA nanoparticles exhibited low cytotoxicity as transfection of B16-F0, U87MG, CHO-1, and Ho-8910 cells produced >80% viability indicating low cytotoxicity of the polymer. The ability of mPPS-FA to deliver EGFP plasmid to melanoma B16-F0, U87, CHO-1, Ho-8910, and A549 cells was investigated in vitro as compared to the lipid-based transfection agent Lipofectamine2000 and Linear PEI 22 kDa (L-PEI 22 kDa). We found that mPPS-FA/DNA complexes yielded the highest GFP transfection efficiency in B16-F0, U87, CHO-1, and Ho-8910 cells, which all highly express folate receptors (FR), at an mPPS-FA/DNA ratio (w/w) of 15. Furthermore, the transfection of mPPS-FA/DNA complexes in CHO-1 cells could be competitively blocked by free folic acid molecules. In contrast, in low FR expressing A549 cells, mPPS-FA showed similar low transfection efficiency as mPPS. Taken together, mPPS-FA showed the highest efficiency in vitro and the potential to be developed as a nonviral gene carrier.

Knockdown of interferon-induced transmembrane protein 1 (IFITM1) inhibits proliferation, migration, and invasion of glioma cells.

Interferon-induced transmembrane protein 1 (IFITM1) has recently been identified as a new molecular marker in human colorectal cancer. However, its role in glioma carcinogenesis is not known. In this study, we demonstrated that suppression of IFITM1 expression significantly inhibited proliferation of glioma cells in a time-dependent manner. The growth inhibitory effect was mediated by cell cycle arrest. Furthermore, IFITM1 knockdown significantly inhibited migration and invasion of glioma cells, which could be attributed to decreased expression and enzymatic activity of matrix metalloproteinase 9. Taken together, these results suggest that IFITM1 is a potential therapeutic target for gliomas.

Adenosine diphosphate-ribosylation factor 6 is required for epidermal growth factor-induced glioblastoma cell proliferation.

BACKGROUND: : Epidermal growth factor (EGF) signaling plays a pivotal role in gliomagenesis. The authors previously demonstrated that adenosine diphospate-ribosylation factor 6 (ARF6), a member of the Ras-related small guanosine-5'-triphospate-binding protein family, is required for EFA6A-induced glioma cell migration and invasion. However, the role of ARF6 in EGF signaling is unknown. METHODS: : The authors analyzed messenger RNA (mRNA) levels of ARF6 and EGF receptor (EGFR) in 16 high-grade glioma samples and in 6 low-grade glioma samples by reverse transcriptase-polymerase chain reaction analysis. To determine whether EGF induces ARF6 expression in human glioblastoma U87 cells through transcriptional regulation and EGFR activation, the levels of ARF6 were assayed in EGF-treated U87 cells that were preincubated with a transcriptional inhibitor (actinomycin D) and an EGFR tyrosine kinase inhibitor (PD153035), respectively. The downstream signaling of EGFR-mediated ARF6 up-regulation also was investigated using specific inhibitors of mitogen-activated protein kinase (MEK), phosphatidylinositol 3' kinase (PI3K), and Janus kinase 2. The involvement of SP1 in the downstream signaling was studied by using an SP1 inhibitor (mithramycin A). Small-interfering RNAs (siRNAs) targeting ARF6 were used to investigate the effects of ARF6 on EGF-mediated glioma cell proliferation. RESULTS: : The results demonstrated that ARF6 and EGFR mRNA levels were elevated in glioma tissues. Furthermore, EGF stimulated ARF6 expression in U87 cells in a dose-dependent and time-dependant manner. This stimulation was caused by increased transcription of ARF6 and by activation of the MEK/extracellular signal-regulated kinase 1 and 2 (ERK1/2) and PI3K signaling pathways. It is noteworthy that SP1 was essential for EGF-induced ARF6 up-regulation. Finally, EGF-induced glioblastoma cell proliferation depended on ARF6, because the suppression of ARF6 by siRNA or by a dominant-negative mutant significantly inhibited EGF-induced cell proliferation. CONCLUSIONS: : The results of the current study suggested that EGF-induced ARF6 expression plays a significant role in glioma cell proliferation. Cancer 2009. (c) 2009 American Cancer Society.

The four-and-a-half-LIM protein 2 (FHL2) is overexpressed in gliomas and associated with oncogenic activities.

Four-and-a-half-LIM protein 2 (FHL2) is a member of FHL protein family, which plays a crucial role in regulating gene expression, cell survival, and migration. Although its function in oncogenesis appears to be tumor type-specific, its roles in glioma formation and development are yet to be elucidated. In the present study, we demonstrated that the mRNA level of FHL2 was elevated in both low- and high-grade glioma samples. Overexpression of FHL2 stimulated the proliferation, anchorage-independent growth, and migration of human glioblastoma cells. Conversely, FHL2 knockdown by short hairpin RNA (shRNA-FHL2) inhibited glioblastoma cell proliferation and migration. Overexpression of FHL2 increased the tumorigenicity of glioblastoma cells in nude mice and decreased the mRNA levels of p53 and its downstream proapoptotic genes, including p21, Bcl2-associated protein X (Bax), and p53-upregulated modulator of apoptosis. It also enhanced the promoter activities of activator protein-1 (AP-1), human telomerase reverse transcriptase, and survivin genes. Together, these results provide the first evidence that FHL2 contributes to glioma carcinogenesis.

Cell cycle-related kinase: a novel candidate oncogene in human glioblastoma.

BACKGROUND: Median survival for patients with glioblastoma multiforme, the most aggressive glioma, is only 12-15 months, despite multimodal treatment that includes surgery, chemotherapy, and radiotherapy. Thus, identification of genes that control the progression of glioblastoma multiforme is crucial for devising new therapies. We investigated the involvement of cell cycle-related kinase (CCRK), a novel protein kinase that is homologous to cyclin-dependent kinase 7, in glioblastoma multiforme carcinogenesis. METHODS: We analyzed the expression levels of CCRK in 26 glioma patient samples (19 high-grade and seven low-grade) and normal brain by semiquantitative reverse transcription-polymerase chain reaction assays. CCRK expression was knocked down in human glioma U-373 MG and U-87 MG cells with small-interfering RNAs and short hairpin RNAs (siCCRK and shCCRK, respectively), and cell proliferation, cell cycle distribution, and cyclin-dependent kinase 2 (CDK2) phosphorylation were examined. A subcutaneous nude mouse xenograft model (n = 4 mice per group) was used to study the effect of CCRK knockdown and overexpression on tumorigenicity and growth of glioblastoma multiforme cells in vivo. All statistical tests were two-sided. RESULTS: CCRK mRNA was elevated at least 1.5-fold and as much as 3.7-fold in 14 (74%) of 19 high-grade glioblastoma multiforme patient samples and in four (80%) of five glioma cell lines examined compared with normal brain tissue. Suppression of CCRK by siCCRK inhibited the proliferation of U-373 MG and U-87 MG glioblastoma cells in a time- and dose-dependent manner. The growth-inhibiting effect of siCCRK was mediated via G1- to S-phase cell cycle arrest and reduced CDK2 phosphorylation. CCRK knockdown statistically significantly suppressed glioma cell growth in vivo as indicated by the mean tumor volumes at week 6 after tumor cell injection (U-373-control = 1352 mm3, U-373-shCCRK = 294 mm3, difference = 1058 mm3, 95% confidence interval [CI] = 677 to 1439 mm3, P<.001; U-87-control = 1910 mm3, U-87-shCCRK = 552 mm3, difference = 1358 mm3, 95% CI = 977 to 1739 mm3, P<.001). CONCLUSIONS: CCRK is a candidate oncogene in glioblastoma multiforme tumorigenesis.

The human secretin gene in children with autistic spectrum disorder: screening for polymorphisms and mutations.

We screened 29 children with autism for mutation in the human secretin gene using single-strand conformation polymorphism. No mutation was detected in exon 2, 3, or 4. Polymerase chain reaction and DNA sequence of 5' variable number of tandem repeats showed two polymorphisms with deletion or duplication of a repeat unit that failed to show any gene expression with transient transfection assay. We did not find evidence of a relationship between human secretin gene mutation and autism.

Gene therapy for colon cancer by adeno-associated viral vector-mediated transfer of survivin Cys84Ala mutant.

BACKGROUND AND AIMS: Reactivation of survivin expression is involved in carcinogenesis and angiogenesis in colon cancer. Previous in vitro studies showed that mutation of the cysteine residue at position 84 (Cys84Ala) of survivin generates a dominant-negative mutant that triggers mitotic catastrophe and apoptosis. We investigated the therapeutic effect of the adeno-associated virus (AAV)-mediated survivin mutant (Cys84Ala) on colon cancer. METHODS: Survivin mutant (Cys84Ala) (Sur-Mut(Cys84Ala)) was cloned into the AAV expression vector pAM/CAG-WPRE.poly(A) to generate recombinant AAV-Sur-Mut(Cys84Ala) virus. Cell proliferation, apoptosis, mitotic catastrophe, and tumor growth were measured in vitro and in vivo. RESULTS: Transduction of colon cancer cells with rAAV-Sur-Mut(Cys84Ala) inhibited cell proliferation and induced apoptosis and mitotic catastrophe in vitro. rAAV-Sur-Mut(Cys84Ala) sensitized colon cancer cells to chemotherapeutic drugs. Furthermore, expression of survivin mutant mediated by AAV inhibited tumorigenesis in colon cancer cells. Intratumoral injection of rAAV-Sur-Mut(Cys84Ala) significantly induced apoptosis and mitotic catastrophe and inhibited angiogenesis and tumor growth in a colon cancer xenograft model in vivo. No obvious cytotoxicity to other tissues was observed. More importantly, rAAV-Sur-Mut(Cys84Ala) expression strongly enhanced the antitumor activity of 5-Fluorouracil (5-FU), resulting in regression of established tumors. CONCLUSIONS: Our results showed that rAAV-Sur-Mut(Cys84Ala) induced apoptosis and mitotic catastrophe and inhibited tumor angiogenesis and tumor growth. Thus, use of AAV-mediated survivin mutant (Cys84Ala) is a promising strategy in colon cancer gene therapy.

Ascorbic acid inhibits ROS production, NF-kappa B activation and prevents ethanol-induced growth retardation and microencephaly.

In this study, we established an embryo model to study the effects of ethanol on fetal development. When embryos of Xenopus laevis (the African clawed frog) were exposed to ethanol, the resultant tadpoles had significantly reduced brain sizes (microencephaly) and retarded growth rates. These effects, similar to those observed in human fetal alcohol syndrome (FAS), were dose- and time-dependent. We further showed that the antioxidant ascorbic acid (vitamin C) could inhibit the ethanol-induced reactive oxygen species (ROS) production and NF-kappaB activation and protect the ethanol-treated embryos against microencephaly and growth retardation. These results suggest the involvement of NF-kappaB and oxidative stress in ethanol-mediated developmental defects, and the potential use of ascorbic acid as a new and effective protective agent for FAS.

Aspartic acid scanning mutation analysis of a goldfish growth hormone-releasing hormone (GHRH) receptor specific to the GHRHsalmon-like peptide.

Growth hormone-releasing hormone (GHRH) plays a pivotal role in the regulation of growth. The study of goldfish GHRH and its receptor is of particular interest as it is so far the only animal model in which two forms of GHRH-like (catfish-like and salmon-like) peptides coexist, and these peptides share only 30-40% of amino acid sequence identities with their mammalian counterparts. For these reasons, we have previously characterized a goldfish GHRH receptor, which is specific for a synthetic carp GHRH-like peptide. In this study, we investigated the structure-function relationships between the receptor and various ligands. Interestingly, among the two endogenous goldfish GHRH-like peptides, only the GHRHsalmon-like peptide was able to stimulate CHO cells transfected with the goldfish GHRH receptor. When the receptor was challenged by GHRHsalmon-like peptide either continuously for 45 min or periodically at 45-min intervals, mild homologous desensitization was observed. To determine whether the negatively charged residues of the receptor are responsible for discriminating GHRHsalmon-like from GHRHcatfish-like, 10 aspartic acid residues residing in the N-terminal ectodomain and the second exoloop were individually mutated to alanine by site-directed mutagenesis. Among these 10 mutants, four of them (D66A, D122A, D190A, and D196A) were defective as indicated by both cAMP assays and extracellular acidification rate measurements. Confocal microscopic studies showed that the D66A and D122A mutants, but not the D190A and D196A mutants, were expressed properly at the plasma membrane. Collectively, these results suggest that aspartic acid residues at positions 66 and 122 are critical for the interaction between the goldfish GHRH receptor and its endogenous ligands.

Protection of Xenopus laevis embryos against alcohol-induced delayed gut maturation and growth retardation by peroxiredoxin 5 and catalase.

Accumulated evidence indicates that maternal alcohol consumption causes fetal enteric damage and growth retardation. In this study, we investigated the underlying molecular mechanisms in a Xenopus model of fetal alcohol exposure. We established a condition of transient alcohol exposure that produces tadpoles with delayed gut maturation and decreased body length. We then investigated the roles of reactive oxygen species (ROS) and reactive nitrogen species (RNS) by microinjecting plasmids expressing catalase and peroxiredoxin 5 (PRDX5) into two-cell stage embryos. Finally, the effects of these enzymes on the expression of key gut developmental genes were determined by animal cap explant assay. We showed that exposure of Xenopus embryos to 0.5% alcohol from stage 13 to stage 22 produced tadpoles with delayed gut maturation, reduced growth, and down-regulation in several gut developmental genes, with VegT, Pax6 and Sox17 most vulnerable. We further demonstrated that microinjection of catalase attenuated alcohol-induced ROS production and restored the expression of VegT and Pax6, but protected the embryos from delayed gut development and retarded growth only partially. By contrast, microinjection of PRDX5 reduced both ROS and RNS production, and prevented the gut and growth defects, and restored VegT, Pax6 and Sox17 gene expression. A positive correlation was found between delayed gut maturation and reduced body length. These results indicate the crucial roles of both the ROS-Pax6 and RNS-Sox17 signaling axes in alcohol-induced fetal gut defects and growth retardation. In addition, they suggest strongly a cause-and-effect relationship between alcohol-induced delayed gut maturation and growth retardation.

A critical role of Pax6 in alcohol-induced fetal microcephaly.

Maternal alcohol abuse during pregnancy is one of the leading causes of birth defects in humans. Despite extensive studies, the molecular basis is still not clear. Here we transiently exposed Xenopus embryos to alcohol and showed that alcohol dose-dependently produced microcephaly and growth retardation. Moreover, it reduced the expression of several key neural genes (xPax6, xOtx2, xSox3, xSox2, and xNCAM), of which xPax6 was most vulnerable. An alcohol concentration as low as 0.3% could produce more than 90% reduction of xPax6 expression. Consistently, microinjection of xPax6 expression plasmid to Xenopus embryos dose-dependently rescued alcohol-induced microcephaly and restored the expression of xOtx2, xSox3, xSox2, and xNCAM. To test whether reactive oxygen species (ROS) is the upstream signal for alcohol-induced microcephaly and xPax6 suppression, we overexpressed catalase in Xenopus embryos and found that catalase not only decreased alcohol-induced H(2)O(2) formation, but also fully restored Pax6 expression and reversed microcephaly. In contrast, xPax6 and catalase could only provide partial protection against growth retardation. Results from this study illustrate for the first time the critical role of H(2)O(2)-mediated Pax6 suppression in alcohol-induced microcephaly and suggest the presence of additional mechanisms for alcohol-induced fetal growth retardation.

Combination of adeno-associated virus and adenovirus vectors expressing bone morphogenetic protein-2 produces enhanced osteogenic activity in immunocompetent rats.

We have previously shown that gene therapy using adeno-associated virus (AAV) carrying bone morphogenetic proteins (BMPs) is a promising strategy for new bone formation in vivo in SD rats. However, it had a relatively low transduction efficiency. We investigate here whether enhanced osteogenic activity can be achieved without eliciting a severe immune response, using a cocktail of AAV-BMP2 and adenovirus (Ad)-BMP2 as a vector system. The muscles of SD rats were injected with either AAV-BMP2, Ad-BMP2, or an AAV-BMP2/Ad-BMP2 cocktail, and the in vivo bone formation was determined at eight weeks post-injection. Radiographic examination demonstrated that the addition of a low level of Ad-BMP2 to AAV-BMP2 produced significantly higher new bone formation than the use of AAV-BMP2 alone. Histological and immunohistological analysis revealed an enlarged bone-forming area and a long-term BMP2 expression, without pronounced infiltration of lymphocytes. Our results provide the first evidence that the introduction of a low level of adenovirus in vivo in immunocompetent subjects can greatly enhance AAV-mediated gene transfer, without inducing severe immune responses. This cocktail vector system may offer an attractive way of improving the efficiency of AAV-based gene delivery.

Catalase and peroxiredoxin 5 protect Xenopus embryos against alcohol-induced ocular anomalies.

PURPOSE: To study the molecular mechanisms underlying alcohol-induced ocular anomalies in Xenopus embryos. METHODS: Xenopus embryos were exposed to various concentrations (0.1%-0.5%) of alcohol, and the subsequent effects in eye development and in eye marker gene expression were determined. To investigate the role of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in fetal alcohol syndrome (FAS)-associated ocular injury, two antioxidant enzymes, catalase and peroxiredoxin 5, were overexpressed in the two blastomeres of the two-cell stage Xenopus embryos. RESULTS: Exposure of Xenopus embryos to alcohol during eye development produced marked gross ocular anomalies, including microphthalmia, incomplete closure of the choroid fissure, and malformation of the retina in 40% of the eyes examined. In parallel, alcohol (0.1%-0.5%) dose dependently and significantly reduced the expression of several eye marker genes, of which TBX5, VAX2, and Pax6 were the most vulnerable. Overexpression of catalase and of cytosolic and mitochondrial peroxiredoxin 5 restored the expression of these alcohol-sensitive eye markers and significantly decreased the frequency of ocular malformation from 39% to 21%, 19%, and 13% respectively. All these enzymes reduced alcohol-induced ROS production, but only peroxiredoxin 5 inhibited RNS formation in the alcohol-treated embryos. CONCLUSIONS: The results suggest that oxidative and nitrosative stresses both contribute to alcohol-induced fetal ocular injury.

A human TERT C-terminal polypeptide sensitizes HeLa cells to H2O2-induced senescence without affecting telomerase enzymatic activity.

We have constructed a 27-kDa hTERT C-terminal polypeptide (hTERTC27) devoid of domains required for telomerase activity and demonstrated that it is capable of nuclear translocation/telomere-end targeting. Here we showed that expression of a low level of hTERTC27 renders hTERT positive HeLa cells sensitive to H(2)O(2)-induced oxidative stress and subsequent cell senescence. The senescence-associated gene, the cyclin/cdk inhibitor p21(Waf1), was up-regulated. This occurs without changing the expression of endogenous hTERT, causing significant telomere shortening or inhibiting telomerase activity. Results from this study suggest for the first time that in addition to telomerase activity, the C-terminus of hTERT also plays a role in hTERT-mediated cellular resistance to oxidative stress.

Secretin as a neuropeptide.

The role of secretin as a classical hormone in the gastrointestinal system is well-established. The recent debate on the use of secretin as a potential therapeutic treatment for autistic patients urges a better understanding of the neuroactive functions of secretin. Indeed, there is an increasing body of evidence pointing to the direction that, in addition to other peptides in the secretin/glucagon superfamily, secretin is also a neuropeptide. The purpose of this review is to discuss the recent data for supporting the neurocrine roles of secretin in rodents. By in situ hybridization and immunostaining, secretin was found to be expressed in distinct neuronal populations within the cerebellum and cerebral cortex, whereas the receptor transcript was found throughout the brain. In the rat cerebellum, secretin functions as a retrograde messenger to facilitate GABA transmission, indicating that it can modulate motor and other functions. In summary, the recent data support strongly the neuropeptide role of secretin, although the secretin-autism link remains to be clarified in the future.