RESUMO
Previous genomewide association studies identified prostate stem cell antigen (PSCA) as a gastric cancer (GC) susceptibility gene and showed an association between GC and the T allele of the single nucleotide polymorphism rs2294008 (C/T) in this gene. The protein product of this gene inhibits cell growth, and the T allele significantly suppresses the transcriptional activity of the -3.2 kb PSCA upstream region. However, the mechanism remains unknown. In this study, we conducted reporter assays using the PSCA upstream region containing the C allele and identified the region from -200 to +38 bp of the transcription initiation site of the gene as a critical region of the -3.2 kb PSCA upstream region. We found that introducing the T allele at rs2294008 generated a consensus binding sequence for the Polycomb group transcription factor Yin Yang 1 (YY1) and that disruption of the consensus sequence restored the transcriptional activity to the -3.2 kb PSCA upstream region. These findings imply that the T allele significantly suppresses PSCA expression in vivo by recruiting YY1 to its promoter, which eventually predisposes gastric epithelial cells to GC development.
Assuntos
Alelos , Antígenos de Neoplasias/genética , Neoplasias da Vesícula Biliar/genética , Neoplasias da Vesícula Biliar/metabolismo , Regulação Neoplásica da Expressão Gênica , Proteínas de Neoplasias/genética , Regiões Promotoras Genéticas , Neoplasias Gástricas/genética , Neoplasias Gástricas/metabolismo , Fator de Transcrição YY1/metabolismo , Sequência de Bases , Sítios de Ligação , Sequência Consenso , Proteínas Ligadas por GPI/genética , Mucosa Gástrica/metabolismo , Mucosa Gástrica/patologia , Ordem dos Genes , Humanos , Dados de Sequência Molecular , Ligação Proteica , Transcrição GênicaRESUMO
Gastric cancer (GC) is one of the major malignant diseases worldwide, especially in Asia, where Japan and Korea have the highest incidence in the world. Gastric cancer is classified into intestinal and diffuse types. While the former is almost absolutely caused by Helicobacter pylori infection as the initial insult, the latter seems to include cases in which the role of infection is limited, if any, and a contribution of genetic factors is anticipated. Previously, we performed a genome-wide association study (GWAS) on diffuse-type GC by using single nucleotide polymorphisms (SNP) catalogued for Japanese population (JSNP), and identified a prostate stem cell antigen (PSCA) gene encoding a glycosylphosphatidylinositol-anchored cell surface antigen as a GC susceptibility gene. From the second candidate locus identified using the GWAS, 1q22, we found the Mucin 1 (MUC1) gene encoding a cell membrane-bound mucin protein as another gene related to diffuse-type GC. A two-allele analysis based on risk genotypes of the two genes revealed approximately 95% of Japanese population have at least one of the two risk genotypes, and approximately 56% of the population have both risk genotypes. The two-SNP genotype might offer ample room to further stratify a high GC risk subpopulation in Japan and Asia by adding another genetic and/or non-genetic factor. Recently, a GWAS on the Chinese population disclosed an additional three GC susceptibility loci: 3q13.31, 5p13.1 and 10q23.
Assuntos
Antígenos de Neoplasias/genética , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Mucina-1/genética , Proteínas de Neoplasias/genética , Neoplasias Gástricas/genética , Ásia/epidemiologia , China/epidemiologia , Proteínas Ligadas por GPI/genética , Genótipo , Glicosilfosfatidilinositóis/genética , Humanos , Japão/epidemiologia , Polimorfismo de Nucleotídeo Único , Neoplasias Gástricas/epidemiologiaRESUMO
BACKGROUND: Prostate stem cell antigen (PSCA), an organ-dependent tumor suppressor, is down regulated in gallbladder cancer (GBC). It is anticipated that the missense allele C of the single nucleotide polymorphism (SNP) rs2294008 (T/C) in the translation initiation codon of the gene affects the gene's biological function and has some influence on GBC susceptibility. We examined the biological effect of the C allele on the function of the gene and the relation between the C allele and GBC susceptibility. MATERIALS AND METHODS: Functional analysis of the SNP was conducted by introducing PSCA cDNA harboring the allele to a GBC cell line TGBC- 1TKB and performing colony formation assays in vitro and tumor formation assays in mice. The effect on transcriptional regulation was assessed by reporter assays. The association study was conducted on 44 Japanese GBC cases and 173 controls. RESULTS: The PSCA cDNA harboring the C allele showed lower cell growth inhibition activity (20% reduction) than that with the T allele. Concordantly, when injected into subcutaneous tissues of mice, the GBC cell line stably expressing the cDNA with the C allele formed tumors of almost the same size as that of the control cells, but the cell line expressing the cDNA with the T allele showed slower growth. The upstream DNA fragment harboring the C allele had more transcriptional activity than that with the T allele. The C allele showed positive correlation to GBC but no statistical significant odds ratio (OR = 1.77, 95% confidence interval 0.85-3.70, P value = 0.127 in dominant model). CONCLUSIONS: The missense allele was shown to have a biological effect, attenuating antitumor activities of PSCA, and consequently it may be a potential risk for GBC development. An association study in a larger sample size may reveal a significant association between the allele and GBC.
RESUMO
Gallbladder cancer (GBC) is relatively rare but has a high mortality rate. One candidate molecule which might be involved in GBC development is prostate stem cell antigen (PSCA), a glycosylphosphatidylinositol-anchored cell surface antigen with a tissue-specific pattern of expression in the epithelium of several organs, such as the prostate, stomach, bladder, and gallbladder. It is up-regulated in a number of cancers including prostate, urinary bladder, and pancreatic cancers, while it is down-regulated in esophageal and gastric cancers, suggesting that PSCA has an oncogenic activity in the former but a tumor suppressor activity in the latter. However, the precise function of PSCA and the regulatory mechanism for its expression in normal and cancer cells are yet to be determined. In this study, immunohistochemical analyses with a specific antibody revealed that PSCA is down-regulated in non-neoplastic gallbladder lesions such as cholesterolosis, cholecystolithiasis, and cholecystitis (9/17; 53%), and also in adenocarcinoma (40/44; 91%), a common neoplasm in gallbladder. Analyses of the DNA methylation status in the GBC cell lines by bisulfite-Pyrosequencing and a reporter assay for the PSCA promoter activity suggested that the down-regulation is explained, at least partly, by DNA methylation. Moreover, colony formation assay revealed that PSCA has cell-proliferation inhibition activity in the GBC cell lines, which was also observed in vivo. These lines of in vivo and in vitro evidence suggest that PSCA is acting as a tumor suppressor in GBC development.
Assuntos
Antígenos de Neoplasias/genética , Transformação Celular Neoplásica/genética , Regulação para Baixo/genética , Neoplasias da Vesícula Biliar/genética , Genes Supressores de Tumor , Proteínas de Neoplasias/genética , Linhagem Celular Tumoral , Proliferação de Células , Colecistite/genética , Metilação de DNA , Epitélio/metabolismo , Proteínas Ligadas por GPI/genética , Vesícula Biliar/metabolismo , Humanos , Masculino , Regiões Promotoras GenéticasRESUMO
Global hypomethylation of leukocyte DNA has been associated with an increased risk of cancer. As dietary and genetic factors related to one-carbon metabolism may influence both the methylation and synthesis of DNA, we investigated associations between these factors and the global methylation level of peripheral blood leukocyte DNA based on a cross-sectional study of 384 Japanese women. Dietary intake of folate and vitamins B2, B6, and B12 was assessed with a validated semiquantitative food frequency questionnaire. Five polymorphisms in methylenetetrahydrofolate reductase (MTHFR) (rs1801133 and rs1801131), methionine synthase (MTR) (rs1805087), and methionine synthase reductase (MTRR) (rs10380 and rs162049) were genotyped. Global DNA methylation of leukocyte DNA was quantified using Luminometric Methylation Assay. A linear trend of association between methylation and dietary and genetic factors was evaluated by regression coefficients in a multivariable linear regression model. Mean global methylation level (standard deviation) was 70.2% (3.4) and range was from 59.0% to 81.2%. Global methylation level significantly decreased by 0.36% (95% confidence interval, 0.03-0.69) per quartile category for folate level. Subgroup analysis suggested that alcohol drinking modified the association between folate intake and global methylation level (P(interaction) = 0.01). However, no statistically significant association was observed for intake of vitamins B2, B6, and B12, alcohol consumption, or five single nucleotide polymorphisms of MTHFR, MTR, and MTRR. We found that higher folate intake was significantly associated with a lower level of global methylation of leukocyte DNA in a group of healthy Japanese females.
Assuntos
Carbono/metabolismo , Metilação de DNA , Dieta , Leucócitos/metabolismo , Adulto , Idoso , Estudos de Casos e Controles , Estudos Transversais , Feminino , Ácido Fólico/administração & dosagem , Predisposição Genética para Doença , Humanos , Metilenotetra-Hidrofolato Redutase (NADPH2)/genética , Metilenotetra-Hidrofolato Redutase (NADPH2)/metabolismo , Polimorfismo de Nucleotídeo Único , Vitamina B 12/administração & dosagem , Vitamina B 6/administração & dosagem , Vitaminas/administração & dosagemRESUMO
BACKGROUND: Although global hypomethylation of leukocyte DNA has been associated with an increased risk of several sites of cancer, including breast cancer, determinants of global methylation level among healthy individuals remain largely unexplored. Here, we examined whether postmenopausal endogenous sex hormones were associated with the global methylation level of leukocyte DNA. METHODS: A cross-sectional study was conducted using the control group of a breast cancer case-control study in Nagano, Japan. Subjects were postmenopausal women aged 55 years or over who provided blood samples. We measured global methylation level of peripheral blood leukocyte DNA by luminometric methylation assay; estradiol, estrone, androstenedione, dehydroepiandrosterone sulfate, testosterone and free testosterone by radioimmunoassay; bioavailable estradiol by the ammonium sulfate precipitation method; and sex-hormone binding globulin by immunoradiometric assay. A linear trend of association between methylation and hormone levels was evaluated by regression coefficients in a multivariable liner regression model. A total of 185 women were included in the analyses. RESULTS: Mean global methylation level (standard deviation) was 70.3% (3.1) and range was from 60.3% to 79.2%. Global methylation level decreased 0.27% per quartile category for estradiol and 0.39% per quartile category for estrone while it increased 0.41% per quartile category for bioavailable estradiol. However, we found no statistically significant association of any sex hormone level measured in the present study with global methylation level of leukocyte DNA. CONCLUSIONS: Our findings suggest that endogenous sex hormones are not major determinants of the global methylation level of leukocyte DNA.
Assuntos
Povo Asiático , Metilação de DNA , Hormônios Esteroides Gonadais/sangue , Leucócitos/metabolismo , Pós-Menopausa/metabolismo , Idoso , Estudos Transversais , Feminino , Humanos , Japão , Pessoa de Meia-Idade , Pós-Menopausa/sangue , Fatores de RiscoRESUMO
The power of an SNP-based genome-wide association study (GWAS) was first demonstrated in Japan using the JSNP database and is currently a major strategy adopted around the world for a number of common diseases including cancers. The hypothesis-free strategy can lead us to a novel hypothesis for carcinogenesis and may contribute to identifying a high risk group for research and, in the future, practice of personalized prevention. We performed a GWAS on diffuse-type gastric cancer and identified a significant association with SNPs in the PSCA (prostate stem cell antigen) gene. The association was validated by a Korean gastric case-control analysis. The PSCA protein is expressed predominantly in the stem cell/precursor-rich region of the gastric epithelium, which is considered as the origin of diffuse-type gastric cancer, and showed tumor suppressor-like characteristics. Individuals with a low PSCA promoter activity are susceptible to diffuse-type gastric cancer. By contrast, the polymorphism does not significantly predispose to intestinal-type gastric cancer, congruous to the hypothesis of the two distinct carcinogenesis pathways for the two major types of gastric cancer. In addition to publication on a specific gene, the sharing of GWAS data through a database on the web is expected to accelerate validation and discovery by other investigators. GeMDBJ (Genome Medicine Database of Japan), started in 2005 in Japan, is one of such attempts. Moreover, the advent of "next generation" sequencers may herald a new era in which the poorly explored domains of the genetic architecture of disease susceptibility may be unveiled.
Assuntos
Estudo de Associação Genômica Ampla , Neoplasias/genética , Polimorfismo de Nucleotídeo Único , Neoplasias Gástricas/genética , Adenocarcinoma/genética , Antígenos de Neoplasias/genética , Proteínas Ligadas por GPI , Genes Dominantes , Predisposição Genética para Doença , Humanos , Japão , Coreia (Geográfico)/epidemiologia , Desequilíbrio de Ligação , Glicoproteínas de Membrana/genética , Modelos Genéticos , Proteínas de Neoplasias/genética , Medição de Risco , Fatores de Risco , Neoplasias Gástricas/epidemiologiaRESUMO
Prostate stem cell antigen (PSCA) is a glycosylphosphatidylinositol (GPI)-anchored cell surface protein and exhibits an organ-dependent expression pattern in cancer. PSCA is upregulated in prostate cancer and downregulated in gastric cancer. PSCA is expressed in a variety of human organs. Although certain studies previously demonstrated its expression in the mammalian and avian brain, its expression in the human brain has not been thoroughly elucidated. Additionally, it was previously reported that PSCA is weakly expressed in the astrocytes of the normal human brain but aberrantly expressed in glioma, suggesting that PSCA is a promising target of glioma therapy and prostate cancer therapy. The current study identified PSCA expression in the neural and choroid plexus cells of the normal human brain by immunohistochemistry. In brain tumors, PSCA was expressed in medulloblastoma and glioma, and its expression was also observed in papilloma and papillary carcinoma of the choroid plexus, ependymoma and meningioma. The results suggest that PSCA may have a tumor-promoting function in brain tumors and is a potential target for their therapy. However, its expression in normal neuronal and choroid plexus cells implies that a PSCA-targeted therapy may lead to certain adverse phenomena.
RESUMO
BACKGROUND/AIM: Overall survival for the high-risk group of neuroblastoma (NB) remains at 40-50%. An integrative genomics study revealed that LIM domain only 1 (LMO1) encoding a transcriptional regulator to be an NB-susceptibility gene with a tumor-promoting activity, that needs to be revealed. MATERIALS AND METHODS: We conducted chromatin immunoprecipitation and DNA sequencing analyses and cell proliferation assays on two NB cell lines. RESULTS: We identified three genes regulated by LMO1 in the cells, LIM and senescent cell antigen-like domains 1 (LIMS1), Ras suppressor protein 1 (RSU1) and relaxin 2 (RLN2). LIMS1 and RSU1 encode proteins functioning with integrin-linked kinase (ILK), and inhibition of LIMS1, ILK or RLN2 by shRNA reduced cell proliferation of the NB cells, which was also suppressed with an ILK inhibiting compound Cpd 22. CONCLUSION: The downstream of LMO1-regulatory cascade includes a tumor-promoting LIMS1/ILK pathway, which has a potential to be a novel therapeutic target.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/genética , Imunoprecipitação da Cromatina/métodos , Proteínas de Ligação a DNA/genética , Regulação Neoplásica da Expressão Gênica , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Proteínas com Domínio LIM/genética , Neuroblastoma/genética , Proteínas Serina-Treonina Quinases/genética , Fatores de Transcrição/genética , Proteínas Adaptadoras de Transdução de Sinal/antagonistas & inibidores , Proliferação de Células , Proteínas de Ligação a DNA/antagonistas & inibidores , Humanos , Proteínas com Domínio LIM/antagonistas & inibidores , Proteínas de Membrana/antagonistas & inibidores , Proteínas de Membrana/genética , Neuroblastoma/metabolismo , Neuroblastoma/patologia , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , RNA Interferente Pequeno/genética , Transdução de Sinais , Fatores de Transcrição/antagonistas & inibidores , Células Tumorais CultivadasRESUMO
BACKGROUND/AIM: In previous work, we found that prostate stem cell antigen (PSCA) gene, encoding a glycosylphosphatidylinositol-anchored protein, is a presumable tumor suppressor in gastric cancer and gallbladder cancer (GBC). The introduction of PSCA cDNA into GBC cell lines significantly suppressed tumorigenecity of cells in mice. The PSCA protein is thought to be involved in some form of intracellular signaling that remains to be elucidated. MATERIALS AND METHODS: Using microarrays, we conducted gene-expression profiling on tumors generated by a GBC cell line TGBC-1TKB, with and without expression of PSCA, which was implanted into mice. Genes whose expression was down-regulated by PSCA were selected, and their down-regulation was confirmed by real-time PCR. RESULTS: We identified several immune-related genes down-regulated by PSCA, including interleukin 8 (IL8), IL1 receptor antagonist (IL1RN) and S100 calcium-binding proteins A8 (S100A8) and A9 (S100A9). CONCLUSION: PSCA signaling may suppress tumor growth in vivo by modulating immunological characteristics of GBC cells.
Assuntos
Antígenos de Neoplasias/genética , Neoplasias da Vesícula Biliar/genética , Glicosilfosfatidilinositóis/biossíntese , Proteínas de Neoplasias/genética , Animais , Antígenos de Neoplasias/biossíntese , Antígenos de Neoplasias/imunologia , Calgranulina A/biossíntese , Calgranulina A/imunologia , Calgranulina B/biossíntese , Calgranulina B/imunologia , Linhagem Celular Tumoral , Proteínas Ligadas por GPI/biossíntese , Proteínas Ligadas por GPI/genética , Proteínas Ligadas por GPI/imunologia , Neoplasias da Vesícula Biliar/imunologia , Neoplasias da Vesícula Biliar/patologia , Regulação Neoplásica da Expressão Gênica , Glicosilfosfatidilinositóis/genética , Glicosilfosfatidilinositóis/imunologia , Humanos , Proteína Antagonista do Receptor de Interleucina 1/biossíntese , Proteína Antagonista do Receptor de Interleucina 1/imunologia , Interleucina-8/biossíntese , Interleucina-8/imunologia , Camundongos , Proteínas de Neoplasias/biossíntese , Proteínas de Neoplasias/imunologiaRESUMO
Prostate stem cell antigen (PSCA) is a glycosylphosphatidylinositol-anchored cell surface antigen with an organ-dependent expression pattern in cancers; e.g., up-regulated in prostate cancer and down-regulated in gastric cancer. Previously it was reported that PSCA is not expressed in the normal pancreas but aberrantly expressed in pancreatic cancer. In this present study, we identified PSCA expression in islets of the pancreas by immunohistochemistry, which was co-localized with four islet-cell markers: insulin, glucagon, somatostatin and pancreatic polypeptide. In our investigation of the transcription start site of PSCA, we found a non-coding splicing variant of PSCA as well as authentic PSCA transcripts in mRNA samples from a normal pancreas. Both the transcripts were also identified in several pancreatic cancer cell lines. We previously reported that PSCA expression is correlated to the methylation status of the enhancer region in gastric and gallbladder cancer cell lines but not in pancreatic cancer cell lines, suggesting that PSCA expression is regulated in a diff erent mode in pancreatic cancer from that in gastric and gallbladder cancers.