Biomedical subjects

J Carl Barrett

Publications and source records attributed to J Carl Barrett.

At least 19 recordsLinked to original sources

PubMed2007

Effects of a catechol-O-methyltransferase inhibitor on catechol estrogen-induced cellular transformation, chromosome aberrations and apoptosis in Syrian hamster embryo cells.

To examine a possible mechanism of endogenous estrogen-induced carcinogenesis, we studied the effect of the catechol-O-methyltransferase (COMT) inhibitor Ro 41-0960 on cell transforming and clastogenic activities of 2 catechol estrogens 2- and 4-hydroxyestrone (2- or 4-OHE1) using Syrian hamster embryo (SHE) cells. COMT activity was assayed by determining the methylation of 2- or 4-OHE1 using gas chromatography. The production of 2-methoxyestrone in cultures treated with 2-OHE1 was approximately 2-fold that of 4-methoxyestrone in cultures treated with 4-OHE1. 4-OHE1 induced morphological transformation at a higher frequency than 2-OHE1 did and the frequencies of cell transformation and chromosome aberrations were not significantly changed in cells treated with 4-OHE1 in the presence of Ro 41-0960. In contrast, the frequencies of cell transformation and chromosome aberrations were markedly increased in cells treated with 2-OHE1 along with Ro 41-0960 when compared to cells treated with 2-OHE1 alone. In addition, both catechol estrogens induced P53 protein expression and apoptosis. The frequencies of apoptotic cells induced by the catechol estrogens were modified by the COMT inhibition in a manner similar to those observed with the chromosome aberrations assay and the cell transformation assay, indicating that each effect by the catechol estrogens at the three measured endpoints might be caused by a mechanism similar to the others. Our findings indicate that COMT activity has an influence on cell transforming activity and its related genetic effects of catechol estrogens in SHE cells, which implies that an individual activity of COMT may be one of the etiological factors in endogenous estrogen-induced carcinogenesis.

Animals↗

PubMed2006

Increased tumor growth in mice with diet-induced obesity: impact of ovarian hormones.

Obesity increases the risk of many cancers in both males and females. This study describes a link between obesity, obesity-associated metabolic alterations, and the risk of developing cancer in male and female mice. The goal of this study was to evaluate the relationship between gender and obesity and to determine the role of estrogen status in obese females and its effect on tumor growth. We examined the susceptibility of C57BL/6 mice to diet-induced obesity, insulin resistance/glucose intolerance, and tumors. Mice were injected sc with one of two tumorigenic cell lines, Lewis lung carcinoma, or mouse colon 38-adenocarcinoma. Results show that tumor growth rate was increased in obese mice vs. control mice irrespective of the tumor cell type. To investigate the effect of estrogen status on tumor development in obese females, we compared metabolic parameters and tumor growth in ovariectomized (ovx) and intact obese female mice. Obese ovx female mice developed insulin resistance and glucose intolerance similar to that observed in obese males. Our results demonstrate that body adiposity increased in ovx females irrespective of the diet administered and that tumor growth correlated positively with body adiposity. Overall, these data point to more rapid tumor growth in obese mice and suggest that endogenous sex steroids, together with diet, affect adiposity, insulin sensitivity, and tumor growth in female mice.

Adenocarcinoma↗

PubMed2006

Cancers as wounds that do not heal: differences and similarities between renal regeneration/repair and renal cell carcinoma.

Cancers have been described as wounds that do not heal, suggesting that the two share common features. By comparing microarray data from a model of renal regeneration and repair (RRR) with reported gene expression in renal cell carcinoma (RCC), we asked whether those two processes do, in fact, share molecular features and regulatory mechanisms. The majority (77%) of the genes expressed in RRR and RCC were concordantly regulated, whereas only 23% were discordant (i.e., changed in opposite directions). The orchestrated processes of regeneration, involving cell proliferation and immune response, were reflected in the concordant genes. The discordant gene signature revealed processes (e.g., morphogenesis and glycolysis) and pathways (e.g., hypoxia-inducible factor and insulin-like growth factor-I) that reflect the intrinsic pathologic nature of RCC. This is the first study that compares gene expression patterns in RCC and RRR. It does so, in particular, with relation to the hypothesis that RCC resembles the wound healing processes seen in RRR. However, careful attention to the genes that are regulated in the discordant direction provides new insights into the critical differences between renal carcinogenesis and wound healing. The observations reported here provide a conceptual framework for further efforts to understand the biology and to develop more effective diagnostic biomarkers and therapeutic strategies for renal tumors and renal ischemia.

Animals↗

PubMed2006

Role of ETS transcription factors in the hypoxia-inducible factor-2 target gene selection.

Tumor hypoxia often directly correlates with aggressive phenotype, metastasis progression, and resistance to chemotherapy. Two transcription factors [hypoxia-inducible factor-1alpha (HIF-1alpha) and HIF-2alpha] are dramatically induced in hypoxic areas and regulate the expression of genes necessary for tumor adaptation to the conditions of low oxygen; however, the relative contribution of these factors is controversial. We used RNA interference-mediated inactivation of HIF-1alpha or HIF-2alpha followed by microarray analysis to identify genes specifically regulated by either HIF-1 or HIF-2 in hypoxia. We found that, in the MCF7 cell line, the vast majority of hypoxia-responsive genes (>80%) were dependent on the presence of HIF-1alpha. However, a small group of genes were preferentially regulated by HIF-2alpha. Promoter analysis for this group of genes revealed that all of them have putative binding sites for ETS family transcription factors, and 10 of 11 HIF-2alpha-dependent genes had at least one potential hypoxia-responsive element (HRE) in proximity to an ETS transcription factor binding site. Knockdown of ELK-1, the most often represented member of ETS family, significantly reduced hypoxic induction of the HIF-2alpha-dependent genes. Physical and functional interaction between ELK-1 and HIF-2alpha were supported by coimmunoprecipitation of these two proteins, luciferase reporter assay using CITED2 promoter, and binding of ELK-1 protein to the promoters of CITED2 and WISP2 genes in proximity to a HRE. These data suggest that the choice of the target genes by HIF-1 or HIF-2 depends on availability and cooperation of HIFs with other factors recognizing their cognate elements in the promoters.

Basic Helix-Loop-Helix Proteins↗

PubMed2006

Accelerated tumor formation in a fatless mouse with type 2 diabetes and inflammation.

Epidemiologic studies show a positive association between obesity and cancer risk. In addition to increased body adiposity and secretion of fat-derived hormones, obesity is also linked to insulin resistance, type 2 diabetes, and chronic inflammation. We used the fatless A-ZIP/F-1 transgenic mouse to dissociate the relative role of each of these underlying factors in the development of cancer. These mice are unique in that they do not have white fat but do develop type 2 diabetes. In two cancer models, the classic two-stage skin carcinogenesis protocol and the C3(1)/T-Ag transgenic mouse mammary tumor model, A-ZIP/F-1 mice displayed higher tumor incidence, tumor multiplicity, and decreased tumor latency than wild-type mice. We examined circulating levels of adipokines, growth factors, and cytokines. As expected, adipokines (i.e., leptin, adiponectin, and resistin) were undetectable or found at very low levels in the blood of fatless mice. However, insulin, insulin-like growth factor-I, growth hormone, vascular endothelial growth factor, and proinflammatory Th2 cytokines, such as interleukin (IL)-1beta, IL-4, and IL-6, were elevated in A-ZIP/F-1 mice. Additionally, we examined multiple phosphorylated proteins (i.e., protein kinase B/Akt and ErbB2/HER-2 kinase) associated with cancer development. Results show that many of these phosphorylated proteins were activated specifically in the A-ZIP/F-1 skin but not in the wild-type skin. These findings suggest that adipokines are not required for the promotion of tumor development and thus contradict the epidemiologic data linking obesity to carcinogenesis. We postulate that insulin resistance and inflammation are responsible for the positive correlation with cancer observed in A-ZIP/F-1 mice.

Adiponectin↗

PubMed2006

Characterization of an antibody that can detect the Kai1/CD82 murine metastasis suppressor.

BACKGROUND: Kai1, also known as CD82, is a member of the tetraspanin family (TM4SF). The human homolog, KAI1, is an activation antigen of T-cells and is a metastasis suppressor for prostate and other cancers. Little is known about the mouse protein because of the lack of antibody reagents. METHODS: Peptide immunized rabbits were used to generate polyclonal antibody to Kai1. The antibody was analyzed using immunoblotting, flow cytometry, and immunohistochemistry. RESULTS: This antibody specifically recognizes murine Kai1 protein, crossreacts with rat Kai1 but not with human KAI1. The normal tissue distribution of this protein in mice is shown to be similar to that of the human homolog. Interestingly, mouse prostatic epithelium showed differential expression within the lobes. CONCLUSION: This antibody, the first described that can specifically detect murine Kai1/CD82, should be very useful in addressing the mechanism of action of Kai1 in metastatic suppression.

Amino Acid Sequence↗

PubMed2006

Genomic instability and aging-like phenotype in the absence of mammalian SIRT6.

The Sir2 histone deacetylase functions as a chromatin silencer to regulate recombination, genomic stability, and aging in budding yeast. Seven mammalian Sir2 homologs have been identified (SIRT1-SIRT7), and it has been speculated that some may have similar functions to Sir2. Here, we demonstrate that SIRT6 is a nuclear, chromatin-associated protein that promotes resistance to DNA damage and suppresses genomic instability in mouse cells, in association with a role in base excision repair (BER). SIRT6-deficient mice are small and at 2-3 weeks of age develop abnormalities that include profound lymphopenia, loss of subcutaneous fat, lordokyphosis, and severe metabolic defects, eventually dying at about 4 weeks. We conclude that one function of SIRT6 is to promote normal DNA repair, and that SIRT6 loss leads to abnormalities in mice that overlap with aging-associated degenerative processes.

Aging↗

PubMed2006

Assessment of genotoxicity of 14 chemical agents used in dental practice: ability to induce chromosome aberrations in Syrian hamster embryo cells.

To assess the genotoxicity of 14 chemical agents used as locally applied agents in dental practice, the ability of these agents to elicit chromosome aberrations was examined using Syrian hamster embryo (SHE) cells. Chromosome aberrations in SHE cells were induced by treatment with three of eight chemical agents used as endodontic medicaments, i.e. ethylenediaminetetraacetic acid (EDTA), formocresol (a mixture of formalin and tricresol), and sodium arsenite. The other five chemical agents, i.e. chloramphenicol, p-chlorophenol, p-phenolsulfonic acid, sodium hypochlorite, and tetracycline hydrochloride exhibited a negative response for chromosome aberrations. Assessment of three dyes used for disclosing dental plaque showed chromosome aberrations induced by basic fuchsin but not by acid fuchsin and erythrosine B. Three local anesthetics, lidocaine hydrochloride, prilocaine hydrochloride, and procaine hydrochloride, were negative for chromosome aberrations. Among the ten chemical agents that exhibited a negative response in the assay, p-chlorophenol, sodium hypochlorite, and erythrosine B induced chromosome aberrations in SHE cells when treated in the presence of exogenous metabolic activation. The percentages of cells with polyploidy or endoreduplication were enhanced by formocresol, sodium arsenite, p-chlorophenol, p-phenolsulfonic acid, sodium hypochlorite, erythrosine B, prilocaine hydrochloride, and procaine hydrochloride in the absence or presence of exogenous metabolic activation. Our results indicate that the chemical agents that had a positive response in the present study are potentially genotoxic to mammalian cells.

Anesthetics↗

PubMed2006

Prediction of lymph node metastasis in patients with endometrioid endometrial cancer using expression microarray.

PURPOSE: To characterize the gene expression profiles of endometrioid endometrial cancers associated with lymph node metastasis in an effort to identify genes associated with metastatic spread. EXPERIMENTAL DESIGN: Tumors from 41 patients with endometrioid endometrial cancer grossly confined to the uterine cavity were evaluated. Positive lymph nodes were noted in 12 of 41 patients. RNA was analyzed for gene expression using the Affymetrix HG133A and HG133B GeneChip set, representing 45,000 array features covering >28,000 UniGene clusters. Data analysis was done using multidimensional scaling, binary comparison, and hierarchical clustering. Gene expression for several differentially expressed genes was examined using quantitative PCR. RESULTS: Gene expression data was obtained from 30,964 genes that were detected in at least 5% of the cases. Supervised analysis of node-positive versus node-negative cases indicated that 450 genes were significantly differentially expressed between the two classes at P < 0.005, 81 of which were differentially expressed by at least 2-fold at P < 0.005. Overexpressed genes included two cell cycle checkpoint genes, CDC2 and MAD2L1, which have previously been described in association with lymph node metastasis in other cancer types. The ZIC2 zinc finger gene was overexpressed in endometrial cancers with positive nodes versus those with negative nodes. CONCLUSION: Gene expression profiling of the primary tumors in patients with endometrioid endometrial cancers seems promising for identifying genes associated with lymph node metastasis. Future studies should address whether the status of nodal metastasis can be determined from the expression profiles of preoperative tissue specimens.

Carcinoma, Endometrioid↗

PubMed2006

Novel human monoclonal antibodies to insulin-like growth factor (IGF)-II that potently inhibit the IGF receptor type I signal transduction function.

The insulin-like growth factor (IGF) system plays an important role in a variety of physiologic processes and in diseases such as cancer. Although the role of the IGF system in cancer has been recognized many years ago, components of the system have only recently been targeted and shown to affect cell transformation, proliferation, survival, motility, and migration in tissue cultures and in mouse models of cancer. We have been hypothesizing that targeting IGF-II in addition to blocking its interaction with the IGF receptor type I (IGF-IR) would also allow to block that portion of the signal transduction through the insulin receptor that is due to its interaction with IGF-II. Lowering its level may also not induce up-regulation of its production as for IGF-I. Finally, targeting a diffusable ligand as IGF-II may not require penetration of the antibody inside tumors but could shift the equilibrium to IGF-II complexed with antibody so the ligand concentration would decrease in the tumor environment without the need for the antibody to penetrate the tumor. Here, we describe the identification and characterization of three novel anti-IGF-II fully human monoclonal antibodies. They bound with high (subnanomolar) affinity to IGF-II, did not cross-react with IGF-I and insulin, and potently inhibited signal transduction mediated by the IGF-IR interaction with IGF-II. The most potent neutralizer, IgG1 m610, inhibited phosphorylation of the IGF-IR and the insulin receptor, as well as phosphorylation of the downstream kinases Akt and mitogen-activated protein kinase with an IC(50) of the order of 1 nmol/L at IGF-II concentration of 10 nmol/L. It also inhibited growth of the prostate cancer cell line DU145 and migration of the breast cancer line cells MCF-7. These results indicate an immunotherapeutic potential of IgG1 m610 likely in combination with other antibodies and anticancer drugs but only further experiments in mouse models of cancer and human clinical trials could evaluate this possibility.

Amino Acid Sequence↗

PubMed2006

Scientific collaboration results in higher citation rates of published articles.

STUDY OBJECTIVE: The primary objective was to analyze the relationship between the citation rate of an article and the extent of collaboration. The secondary objective was to analyze the relationship between the number of authors/article and the number of institutions/article for the period of study. METHODS: We counted the number of original research articles published in six leading journals--Cell, Science, Nature, New England Journal of Medicine, The Lancet, and Journal of the American Medical Association--for the years 1975, 1985, and 1995. For each article, we determined the number of authors and the number of separate institutions. We also determined the number of times each article that was published in 1995 was cited in future scientific articles from the Science Citation Index database. RESULTS: Science, Cell, Nature, New England Journal of Medicine, The Lancet, and Journal of the American Medical Association had 2014, 868, 3856, 643, 785, and 465 total articles published/3-year study period, respectively. There was a median of 2, 2, 2, 3, 3, and 3 institutions/article, respectively. All of the final models had a significant linear author component for which all of the parameter estimates were positive, yet variable. Thus, the number of times an article was cited correlated significantly with the number of authors and the number of institutions. CONCLUSION: A correlation exists between the number of authors and the number of times an article is cited in other articles. Investigators who are open to collaborations and those who seem to adequately manage those collaborations produce a superior product that results in a higher impact.

Authorship↗

PubMed2005

Differential cis-regulation of human versus mouse TERT gene expression in vivo: identification of a human-specific repressive element.

In vivo expression of human telomerase is significantly different from that of mouse telomerase. To assess the basis for this difference, a bacterial artificial chromosome clone containing the entire hTERT (human telomerase reverse transcriptase) gene was introduced in mice. In these transgenic mice, expression of the hTERT transgene was similar to that of endogenous hTERT in humans, rather than endogenous mTERT (mouse telomerase reverse transcriptase). In tissues and cells showing a striking difference in expression levels between hTERT in humans and mTERT in mice (i.e., liver, kidney, lung, uterus, and fibroblasts), expression of the hTERT transgene in transgenic mice was repressed, mimicking hTERT in humans. The transcriptional activity of the hTERT promoter was much lower than that of the mTERT promoter in mouse embryonic fibroblasts or human fibroblasts. Mutational analysis of the hTERT and mTERT promoters revealed that a nonconserved GC-box within the hTERT promoter was responsible for the human-specific repression. These results reveal that a difference in cis-regulation of transcription, rather than transacting transcription factors, is critical to species differences in tissue-specific TERT expression. Our data also suggest that the GC-box-mediated, human-specific mechanism for TERT repression is impaired in human cancers. This study represents a detailed characterization of the functional difference in a gene promoter of mice versus humans and provides not only important insight into species-specific regulation of telomerase and telomeres but also an experimental basis for generating mice humanized for telomerase enzyme and its pattern of expression.

Animals↗

PubMed2005

Expression profiling of serous low malignant potential, low-grade, and high-grade tumors of the ovary.

Papillary serous low malignant potential (LMP) tumors are characterized by malignant features and metastatic potential yet display a benign clinical course. The role of LMP tumors in the development of invasive epithelial cancer of the ovary is not clearly defined. The aim of this study is to determine the relationships among LMP tumors and invasive ovarian cancers and identify genes contributing to their phenotypes. Affymetrix U133 Plus 2.0 microarrays (Santa Clara, CA) were used to interrogate 80 microdissected serous LMP tumors and invasive ovarian malignancies along with 10 ovarian surface epithelium (OSE) brushings. Gene expression profiles for each tumor class were used to complete unsupervised hierarchical clustering analyses and identify differentially expressed genes contributing to these associations. Unsupervised hierarchical clustering analysis revealed a distinct separation between clusters containing borderline and high-grade lesions. The majority of low-grade tumors clustered with LMP tumors. Comparing OSE with high-grade and LMP expression profiles revealed enhanced expression of genes linked to cell proliferation, chromosomal instability, and epigenetic silencing in high-grade cancers, whereas LMP tumors displayed activated p53 signaling. The expression profiles of LMP, low-grade, and high-grade papillary serous ovarian carcinomas suggest that LMP tumors are distinct from high-grade cancers; however, they are remarkably similar to low-grade cancers. Prominent expression of p53 pathway members may play an important role in the LMP tumor phenotype.

Carcinoma, Papillary↗

PubMed2005

CD82 metastasis suppressor gene: a potential target for new therapeutics?

The transmembrane glycoprotein CD82 is a member of the tetraspanin protein family and is a metastasis suppressor implicated in biological processes ranging from fusion, adhesion and migration to apoptosis and cell-morphology alterations. Downregulation of CD82 expression is associated with the advanced stages of many human cancers and correlates with the acquisition of metastatic potential. Recent studies suggest that complex mechanisms underlie CD82 loss of function, including altered transcriptional regulation, splice variant production and post-translational protein modifications, and indicate a central role for CD82 in controlling metastasis as a 'molecular facilitator'. The diverse array of functions of CD82, the complexity of the regulation of CD82 and the prospects for targeting CD82 as a therapeutic approach for the treatment of a variety of metastatic cancers are discussed.

Gene Expression Regulation, Neoplastic↗

PubMed2005

Gene expression profiles of serous, endometrioid, and clear cell subtypes of ovarian and endometrial cancer.

PURPOSE: The presence of similar histologic subtypes of epithelial ovarian and endometrial cancers has long been noted, although the relevance of this finding to pathogenesis and clinical management is unclear. Despite similar clinical characteristics, histologic subtypes of cancers of the ovary and endometrium are treated according to organ of origin. This study compares the gene expression profiles of analogous histologic subtypes of cancers of the ovary and endometrium using the same genomic platform to determine the similarities and differences between these tumors. EXPERIMENTAL DESIGN: Gene expression profiles of 75 cancers (endometrioid, serous, and clear cell) of the ovary and endometrium, five renal clear cell cancers, and seven normal epithelial brushings were determined using a 11,000-element cDNA array. All images were analyzed using BRB ArrayTools. Validation was done using real-time PCR on select genes and immunohistochemical staining. RESULTS: Comparison across endometrial and ovarian cancers and serous and endometrioid tumors showed expression patterns reflecting their organ of origin. Clear cell tumors, however, showed remarkably similar expression patterns regardless of their origin, even when compared with renal clear cell samples. A set of 43 genes was common to comparisons of each of the three histologic subtypes of ovarian cancer with normal ovarian surface epithelium. CONCLUSIONS: The comparison of the gene expression profiles of endometrioid and serous subtypes of ovarian and endometrial cancer are largely unique to the combination of a particular subtype in a specific organ. In contrast, clear cell cancers show a remarkable similarity in gene expression profiles across organs (including kidney) and could not be statistically distinguished.

Adenocarcinoma, Clear Cell↗

PubMed2005

Upregulation of the KIAA1199 gene is associated with cellular mortality.

The microcell-mediated transfer of a normal human chromosome 3 induces replicative senescence in otherwise immortal renal cell carcinoma cells. To identify the genes involved in the chromosome 3-induced cellular mortality, we previously performed a cDNA subtraction experiment using the immortal renal cell carcinoma cells (RCC23) and the mortal counterpart with the transferred chromosome 3 (RCC23+3). We here report the cDNA cloning and characterization of one of the differentially expressed genes, which encodes KIAA1199 protein of unknown function. Northern blot and RT-PCR analyses revealed striking upregulation of KIAA1199 mRNA in mortal RCC23+3 compared with immortal RCC23. However, no significant change in KIAA1199 mRNA expression was observed during replicative aging in vitro (from early passage culture to senescent culture) of mortal human cells including RCC23+3, normal fibroblasts and prostate epithelial cells. Interestingly, an immortal fibroblast cell line and two breast cancer cell lines expressed much lower amounts of KIAA1199 mRNA than their normal counterparts. KIAA1199 mRNA is expressed in a wide range of normal human tissues, with the highest level of expression in brain. The gene is located on chromosome band 15q25, where a brain tumor suppressor gene has been mapped. These findings suggest that KIAA1199 gene may play a role in cellular mortality of normal human cells, which counters cell immortalization and carcinogenesis.

Breast Neoplasms↗

PubMed2005

Rapid generation of long synthetic tandem repeats and its application for analysis in human artificial chromosome formation.

Human artificial chromosomes (HACs) provide a unique opportunity to study kinetochore formation and to develop a new generation of vectors with potential in gene therapy. An investigation into the structural and the functional relationship in centromeric tandem repeats in HACs requires the ability to manipulate repeat substructure efficiently. We describe here a new method to rapidly amplify human alphoid tandem repeats of a few hundred base pairs into long DNA arrays up to 120 kb. The method includes rolling-circle amplification (RCA) of repeats in vitro and assembly of the RCA products by in vivo recombination in yeast. The synthetic arrays are competent in HAC formation when transformed into human cells. As short multimers can be easily modified before amplification, this new technique can identify repeat monomer regions critical for kinetochore seeding. The method may have more general application in elucidating the role of other tandem repeats in chromosome organization and dynamics.

Cell Line, Tumor↗

PubMed2005

Reciprocal binding of CTCF and BORIS to the NY-ESO-1 promoter coincides with derepression of this cancer-testis gene in lung cancer cells.

Regulatory sequences recognized by the unique pair of paralogous factors, CTCF and BORIS, have been implicated in epigenetic regulation of imprinting and X chromosome inactivation. Lung cancers exhibit genome-wide demethylation associated with derepression of a specific class of genes encoding cancer-testis (CT) antigens such as NY-ESO-1. CT genes are normally expressed in BORIS-positive male germ cells deficient in CTCF and meCpG contents, but are strictly silenced in somatic cells. The present study was undertaken to ascertain if aberrant activation of BORIS contributes to derepression of NY-ESO-1 during pulmonary carcinogenesis. Preliminary experiments indicated that NY-ESO-1 expression coincided with derepression of BORIS in cultured lung cancer cells. Quantitative reverse transcription-PCR analysis revealed robust, coincident induction of BORIS and NY-ESO-1 expression in lung cancer cells, but not normal human bronchial epithelial cells following 5-aza-2'-deoxycytidine (5-azadC), Depsipeptide FK228 (DP), or sequential 5-azadC/DP exposure under clinically relevant conditions. Bisulfite sequencing, methylation-specific PCR, and chromatin immunoprecipitation (ChIP) experiments showed that induction of BORIS coincided with direct modulation of chromatin structure within a CpG island in the 5'-flanking noncoding region of this gene. Cotransfection experiments using promoter-reporter constructs confirmed that BORIS modulates NY-ESO-1 expression in lung cancer cells. Gel shift and ChIP experiments revealed a novel CTCF/BORIS-binding site in the NY-ESO-1 promoter, which unlike such sites in the H19-imprinting control region and X chromosome, is insensitive to CpG methylation in vitro. In vivo occupancy of this site by CTCF was associated with silencing of the NY-ESO-1 promoter, whereas switching from CTCF to BORIS occupancy coincided with derepression of NY-ESO-1. Collectively, these data indicate that reciprocal binding of CTCF and BORIS to the NY-ESO-1 promoter mediates epigenetic regulation of this CT gene in lung cancer cells, and suggest that induction of BORIS may be a novel strategy to augment immunogenicity of pulmonary carcinomas.

Antigens, Neoplasm↗