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Ectopic Overexpression (ectopic + overexpression)

Distribution by Scientific Domains

Medical Sciences	66%
Life Sciences	25%

Selected Abstracts

TIP30 is associated with progression and metastasis of prostate cancer

INTERNATIONAL JOURNAL OF CANCER, Issue 4 2008
Hui Zhang
Abstract Tat-interacting protein 30 (TIP30), a transcriptional repressor for ER,-mediated transcription, possesses several characteristics of a tumor suppressor in certain human and mouse cells. It is reported that deletion of TIP30 gene preferentially increases tumorigenesis in the female knockout mice. Here, we analyzed TIP30 gene expression in the databases of several DNA microarray studies of human prostate cancer and show that TIP30 is specifically overexpressed in metastatic prostate cancers. We demonstrate that TIP30 nuclear expression is associated with prostate cancer progression and metastasis by immunohistochemical analysis in primary and metastatic prostate cancers. Consistent with these data, we also show that knockdown of TIP30 expression, through use of a short hairpin RNA-expressing plasmid, suppresses the cellular growth of PC3 and LNCaP prostate cancer cells. Ectopic overexpression of TIP30 stimulates metastatic potential of prostate cancer cells in an in vitro invasion assay, whereas knockdown of TIP30 inhibits the prostate cancer cells invasion. Finally, we demonstrate that ectopic overexpression of TIP30 enhances androgen receptor mediated transcription, whereas knockdown of TIP30 results in a decreased transcription activity. These data provide evidence that TIP30 plays a role in prostate cancer progression and that TIP30 overexpression may promote prostate cancer cell growth and metastasis. © 2008 Wiley-Liss, Inc. [source]

Overexpression of Smurf2 Stimulates Endochondral Ossification Through Upregulation of ,-Catenin,

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 4 2008
Qiuqian Wu MD
Abstract Ectopic expression of Smurf2 in chondrocytes and perichondrial cells accelerated endochondral ossification by stimulating chondrocyte maturation and osteoblast development through upregulation of ,-catenin in Col2a1-Smurf2 embryos. The mechanism underlying Smurf2-mediated morphological changes during embryonic development may provide new mechanistic insights and potential targets for prevention and treatment of human osteoarthritis. Introduction: Our recent finding that adult Col2a1-Smurf2 mice have an osteoarthritis-like phenotype in knee joints prompted us to examine the role of Smurf2 in the regulation of chondrocyte maturation and osteoblast differentiation during embryonic endochondral ossification. Materials and Methods: We analyzed gene expression and morphological changes in developing limbs by immunofluorescence, immunohistochemistry, Western blot, skeletal preparation, and histology. A series of markers for chondrocyte maturation and osteoblast differentiation in developing limbs were examined by in situ hybridization. Results: Ectopic overexpression of Smurf2 driven by the Col2a1 promoter was detected in chondrocytes and in the perichondrium/periosteum of 16.5 dpc transgenic limbs. Ectopic Smurf2 expression in cells of the chondrogenic lineage inhibited chondrocyte differentiation and stimulated maturation; ectopic Smurf2 in cells of the osteoblastic lineage stimulated osteoblast differentiation. Mechanistically, this could be caused by a dramatic increase in the expression of ,-catenin protein levels in the chondrocytes and perichondrial/periosteal cells of the Col2a1-Smurf2 limbs. Conclusions: Ectopic expression of Smurf2 driven by the Col2a1 promoter accelerated the process of endochondral ossification including chondrocyte maturation and osteoblast differentiation through upregulation of ,-catenin, suggesting a possible mechanism for development of osteoarthritis seen in these mice. [source]

ANAC012, a member of the plant-specific NAC transcription factor family, negatively regulates xylary fiber development in Arabidopsis thaliana

THE PLANT JOURNAL, Issue 6 2007
Jae-Heung Ko
Summary Vascular plants evolved to have xylem that provides physical support for their growing body and serves as a conduit for water and nutrient transport. In a previous study, we used comparative-transcriptome analyses to select a group of genes that were upregulated in xylem of Arabidopsis plants undergoing secondary growth. Subsequent analyses identified a plant-specific NAC-domain transcription factor gene (ANAC012) as a candidate for genetic regulation of xylem formation. Promoter-GUS analyses showed that ANAC012 expression was preferentially localized in the (pro)cambium region of inflorescence stem and root. Using yeast transactivation analyses, we confirmed the function of ANAC012 as a transcriptional activator, and identified an activation domain in the C terminus. Ectopic overexpression of ANAC012 in Arabidopsis (35S::ANAC012 plants) dramatically suppressed secondary wall deposition in the xylary fiber and slightly increased cell-wall thickness in the xylem vessels. Cellulose compositions of the cell wall were decreased in the inflorescent stems and roots of 35S::ANAC012 plants, probably resulting from defects in xylary fiber formation. Our data suggest that ANAC012 may act as a negative regulator of secondary wall thickening in xylary fibers. [source]

Functions of cyclin D1 as an oncogene and regulation of cyclin D1 expression

CANCER SCIENCE, Issue 5 2007
Etsu Tashiro
Cyclin D1 binds to the Cdk4 and Cdk6 to form a pRB kinase. Upon phosphorylation, pRB loses its repressive activity for the E2F transcription factor, which then activates transcription of several genes required for the transition from the G1- to S-phase and for DNA replication. The cyclin D1 gene is rearranged and overexpressed in centrocytic lymphomas and parathyroid tumors and it is amplified and/or overexpressed in a major fraction of human tumors of various types of cancer. Ectopic overexpression of cyclin D1 in fibroblast cultures shortens the G1 phase of the cell cycle. Furthermore, it has been demonstrated that introduction of an antisense cyclin D1 into a human carcinoma cell line, in which the cyclin D1 gene is amplified and overexpressed, causes reversion of the malignant phenotype. Thus, increased expression of cyclin D1 can play a critical role in tumor development and in maintenance of the malignant phenotype. However, it is insufficient to confer transformed properties on primary or established fibroblasts. In this review, we summarize the role of cyclin D1 on tumor development and malignant transformation. In addition, our chemical biology study to understand the regulatory mechanism of cyclin D1 transcription is also reviewed. (Cancer Sci 2007; 98: 629,635) [source]

Human inhibitor of growth 1 inhibits hepatoma cell growth and influences p53 stability in a variant-dependent manner,

HEPATOLOGY, Issue 2 2009
Zhi Zhu
Inhibitor of growth 1 (ING1) is a type II tumor suppressor that affects cell function by altering chromatin structure and regulating transcription. Recently, three ING1 splice variants have been cloned, but their roles in apoptosis and p53 regulation in human hepatocellular carcinoma (HCC) have not been fully elucidated. The present study found that ING1, in a variant-dependent manner, inhibited hepatoma cell proliferation and colony formation, induced apoptosis and cell cycle arrest at G0/G1 phase, and postponed tumor formation in nude mice. Expression of p33ING1b and p24ING1c variants, but not p47ING1a, was markedly reduced in HCC samples. Reverse transcription polymerase chain reaction and western blotting analysis revealed that ectopic overexpression of p33ING1b or p24ING1c variant increased the expression of p53 downstream genes such as p21waf1 and bax, and repressed bcl-2 expression (P < 0.01), whereas p47ING1a inactivated p21waf1 promoter (P < 0.01). Furthermore, we found that p33ING1b and p24ING1c repressed Mdm2 expression (P < 0.01) and competed with Mdm2 for binding to p53. Interestingly, p33ING1band p24ING1c did not directly bind to Mdm2 protein but strongly increased p14arf expression (P < 0.01) and interacted with p14arf protein to stimulate p53. Moreover, we found that ectopic overexpression of p33ING1b or p24ING1c significantly induced p53 protein acetylation at Lys-373/Lys-382 residue, but did not alter the phosphorylation status of p53. Conclusion: ING1 variants p33ING1b and p24ING1c may modulate p53 activity and subsequently inhibit hepatoma cell growth by at least two possible mechanisms: interacting with Mdm2 and p14arf to stabilize and activate p53, or increasing p53 acetylation. (HEPATOLOGY 2009.) [source]

TIP30 is associated with progression and metastasis of prostate cancer

Regulation of embryonic endochondral ossification by Smurf2

JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 5 2008
Qiuqian Wu
Abstract Smurf2 is an E3 ubiquitin ligase that targets TGF-, receptor activated Smad2 and Smad3 for the proteasome in primary articular chondrocytes, thus stimulating their hypertrophic differentiation. Comparatively, how Smurf2 functions in growth plate chondrocytes in a developing long bone is an open question. In this study, we measured the mRNA levels of endogenous Smurf2 and type X collagen in chick growth plate at different embryonic stages to monitor the correlation between the level of Smurf2 expression and chondrocyte maturational stage. We found that high levels of Smurf2 were associated with the differentiative and proliferative stages, while Smurf2 levels were thereafter decreased as the chondrocytes matured toward hypertrophy. In addition, we injected Smurf2 -RCAS into chick wing buds at HH stage 20,23 and examined how the ectopic overexpression of Smurf2 in condensing chondrogenic mesenchyme affects the subsequent process of chondrocyte maturation and ossification during embryonic development. Histological analysis showed that overexpression of Smurf2 in a developing wing bud accelerated chondrocyte maturation and endochondral ossification, which may result from a decrease in TGF-, signaling in the infected chondrocytes with Smurf2 -RCAS. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:704,712, 2008 [source]

The functional ,443T/C osteopontin promoter polymorphism influences osteopontin gene expression in melanoma cells via binding of c-Myb transcription factor

MOLECULAR CARCINOGENESIS, Issue 1 2009
Julia Schultz
Abstract In the present report, the possible role of a recently described functional polymorphism of the osteopontin (OPN) promoter at position ,443 (,443T/C) for OPN expression in melanoma cells was addressed. As shown by real-time PCR analysis, melanoma metastases that were homozygous for the ,443C allele expressed significantly higher levels of OPN mRNA compared with those that were either heterozygous (,443T/C) or homozygous for the ,443T allele. In line with this, immunoblotting showed significantly enhanced baseline and bFGF-induced OPN protein expression in melanoma cell lines which were homozygous for the ,443C allele, compared with cell lines with other allelic variants. Similar results were obtained in in vitro luciferase assays. Chromatin immunoprecipitation (ChIP) demonstrated binding of c-Myb to the ,443 OPN promoter region, and binding could significantly be enhanced after bFGF stimulation. Moreover, as shown by electrophoretic mobility shift assays (EMSA), recombinant DNA-binding domain of c-Myb bound in a sequence-specific manner to this region. Finally, the role of c-Myb for OPN gene regulation via binding to the ,443 promoter region could be further substantiated by ectopic overexpression of c-Myb in melanoma cells, using different reporter gene constructs. Taken together, it is demonstrated that the ,443 promoter region exerts influence on OPN gene expression in melanoma cells, and differential binding of c-Myb transcription factor appears to play a major role in this process. These findings might be a feasible explanation for different OPN expression levels in metastatic tumors and may also have prognostic and therapeutic relevance. © 2008 Wiley-Liss, Inc. [source]

Serine/threonine kinase PKR: A sentinel kinase that discriminates a signaling pathway mediated by TLR4 from those mediated by TLR3 and TLR9

AMERICAN JOURNAL OF HEMATOLOGY, Issue 7 2007
Yusuke Asakura
Abstract Cells of the innate immune system discriminate between "noninfectious self" and "infectious nonself" via pattern recognition receptors known as Toll-like receptors (TLRs). Though TLRs and the related interleukin 1 receptors share considerable homology in their cytoplasmic domains and adaptor molecules, signaling cascades may substantially differ from one another depending on the adaptor proteins recruited. Here we show that ectopic overexpression of catalytically inactive dominant-negative PKR expression system suppressed NF- , B activation mediated by TLR3, TLR9, TNF receptor 1 and 2 (TNF-R 1/2), but not by TLR4. Physiological relevance of the observations described here are discussed. Am. J. Hematol 2007. © 2006 Wiley-Liss, Inc. [source]

Chloride intracellular channel 1 identified using proteomic analysis plays an important role in the radiosensitivity of HEp-2 cells via reactive oxygen species production

PROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 14 2010
Jae-Sung Kim
Abstract The nature of the molecules underlying the radioresistance phenotype of laryngeal cancer cells remains to be established. We initially generated radioresistant laryngeal cancer cell lines from human HEp-2 cells with fractionated radiation. These RR-HEp-2 cells and isolated clones displayed more radioresistant and anti-apoptotic phenotypes than parental HEp-2 cells after radiation. Characteristics of RR-Hep-2 cell lines were confirmed by upregulation of radioresistance-related genes, such as epidermal growth factor receptor, Hsp90, and Bcl-xl. Subsequently, we examined proteome changes between HEp-2 and RR-HEp-2 cells and identified 16 proteins showing significantly altered expression levels. Interestingly, protein expression of chloride intracellular channel 1 (CLIC1) was markedly suppressed in RR-HEp-2 cells, compared with non-irradiated control cells. Suppression of CLIC1 with an indanyloxyacetic acid-94 or small interfering RNA led to radioresistance in HEp-2 cells by suppressing the radiation-induced cellular ROS level. However, ectopic overexpression of CLIC1 induced radiosensitivity in RR-HEp-2 cells via induction of ROS level after radiation, suggesting that the protein acts as a positive regulator of ROS production. Our results collectively indicate that suppression of CLIC1 contributes to acquisition of the radioresistance phenotype of laryngeal cancer cells via inhibition of ROS production, implying that this protein is an important candidate molecule for radiotherapy in radioresistant laryngeal cancer cells. [source]

NtSET1, a member of a newly identified subgroup of plant SET-domain-containing proteins, is chromatin-associated and its ectopic overexpression inhibits tobacco plant growth

THE PLANT JOURNAL, Issue 4 2001
Wen-Hui Shen
Summary The SET- and chromo-domains are recognized as signature motifs for proteins that contribute to epigenetic control of gene expression through effects on the regional organization of chromatin structure. This paper reports the identification of a novel subgroup of SET-domain-containing proteins in tobacco and Arabidopsis, which show highest homologies with the Drosophila position-effect-variegation repressor protein SU(VAR)3,9 and the yeast centromer silencing protein CLR4. The tobacco SET-domain-containing protein (NtSET1) was fused to the green fluorescence protein (GFP) that serves as a visual marker for localization of the recombinant protein in living cells. Whereas control GFP protein alone was uniformly dispersed within the nucleus and cytoplasm, the NtSET1-GFP fusion protein showed a non-uniform localization to multiple nuclear regions in interphase tobacco TBY2 cells. During mitosis, the NtSET1-GFP associated with condensed chromosomes with a non-random distribution. The NtSET1 thus appears to have distinct target regions in the plant chromatin. Overexpression of the NtSET1-GFP in transgenic tobacco inhibited plant growth, implicating the possible involvement of the NtSET1 in transcriptional repression of growth control genes through the formation of higher-order chromatin domains. [source]

ITCH is a putative target for a novel 20q11.22 amplification detected in anaplastic thyroid carcinoma cells by array-based comparative genomic hybridization

CANCER SCIENCE, Issue 10 2008
Takaya Ishihara
Anaplastic thyroid carcinoma (ATC) is one of the most virulent of all human malignancies, with a mean survival time among patients of less than 1 year after diagnosis. To date, however, cytogenetic information on this disease has been very limited. During the course of a program to screen a panel of ATC cell lines for genomic copy-number aberrations using array-based comparative genomic hybridization, we identified a high-level amplification of the ITCH gene, which is mapped to 20q11.22 and belongs to the homologous to the E6-associated protein carboxylterminus ubiquitin ligase family. The expression of ITCH was increased in 4 of 14 ATC cell lines (28.6%), including 8305C in which there was a copy-number amplification of this gene, and six of seven primary cases (85.7%). Among the primary thyroid tumors, a considerable number of ITCH high expressers was found in ATC (40/45, 88.9%), papillary thyroid carcinoma (25/25, 100%), and papillary microcarcinoma (25/25, 100%). Furthermore, knockdown of ITCH by specific small interfering RNA significantly inhibited the growth of ITCH-overexpressing cells, whereas ectopic overexpression of ITCH promoted growth of ATC cell lines with relatively weak expression. These observations indicate ITCH to be the most likely target for 20q11.22 amplification and to play a crucial role in the progression of thyroid carcinoma. (Cancer Sci 2008; 99: 1940,1949) [source]