title: SNP55, a new functional polymorphism of MDM2-P2 promoter, contributes to allele-specific expression of MDM2 in endometrial cancers.
abstract: BACKGROUND
  The functional single nucleotide polymorphism (SNP) in the MDM2 promoter region, SNP309, is known to be associated with various diseases, particularly cancer. Although many studies have been performed to demonstrate the mechanism of allele-specific expression (ASE) on SNP309, they have only utilized in vitro techniques. It is unknown whether ASE of MDM2 is ascribed solely to SNP309, in vivo.
  
  
  METHODS
  We attempted to evaluate ASE of MDM2 in vivo using post-labeling followed by automated capillary electrophoresis under single-strand conformation polymorphism conditions. For measuring a quantitative difference, we utilized the SNPs on the exons of MDM2 as markers, the status of which was heterozygous in a large population. To address the cause of ASE beyond 20%, we confirmed sequences of both MDM2-3'UTR and promoter regions. We assessed the SNP which might be the cause of ASE using biomolecular interaction analysis and luciferase assay.
  
  
  RESULTS
  ASE beyond 20% was detected in endometrial cancers, but not in cancer-free endometria samples only when an SNP rs1690916 was used as a marker. We suspected that this ASE in endometrial cancer was caused by the sequence heterogeneity in the MDM2-P2 promoter, and found a new functional polymorphism, which we labelled SNP55. There was no difference between cancer-free endometria and endometrial cancer samples neither for SNP55 genotype frequencies nor allele frequencies, and so, SNP55 alone does not affect endometrial cancer risk. The SNP55 status affected the DNA binding affinity of transcription factor Sp1 and nuclear factor kappa-B (NFκB). Transcriptional activity of the P2 promoter containing SNP55C was suppressed by NFκB p50 homodimers, but that of SNP55T was not. Only ASE-positive endometrial cancer samples displayed nuclear localization of NFκB p50.
  
  
  CONCLUSIONS
  Our findings suggest that both the SNP55 status and the NFκB p50 activity are important in the transcriptional regulation of MDM2 in endometrial cancers.
authors: Department of Obstetrics and Gynecology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan. kanaronron@hotmail.com.
authors: Kanako
authors: K
authors: Okamoto
authors: Department of Obstetrics and Gynecology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan. tsunematsu.ryosuke@ibusuki2.hosp.go.jp.|Current address: Department of Obstetrics and Gynecology, National Hospital Organization Ibusuki Medical Center, 4145, Junicho, Ibusuki, Kagoshima, 891-0498, Japan. tsunematsu.ryosuke@ibusuki2.hosp.go.jp.
authors: Ryosuke
authors: R
authors: Tsunematsu
authors: Innovation Center for Medical Redox Navigation, Kyushu University, Fukuoka, Japan. tomo.tahira@gmail.com.
authors: Tomoko
authors: T
authors: Tahira
authors: Department of Obstetrics and Gynecology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan. kenzo@med.kyushu-u.ac.jp.
authors: Kenzo
authors: K
authors: Sonoda
authors: Department of Obstetrics and Gynecology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan. asanoma@med.kyushu-u.ac.jp.
authors: Kazuo
authors: K
authors: Asanoma
authors: Department of Obstetrics and Gynecology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan. yagih@med.kyushu-u.ac.jp.
authors: Hiroshi
authors: H
authors: Yagi
authors: Department of Obstetrics and Gynecology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan. irotomo@nifty.com.
authors: Tomoko
authors: T
authors: Yoneda
authors: Division of Genome Analysis, Research Center for Genetic Information, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan. hayashi.kenshi@gmail.com.
authors: Kenshi
authors: K
authors: Hayashi
authors: Research Center for Environmental Medical Sciences, Kyushu University, Fukuoka, Japan. wake@med.kyushu-u.ac.jp.
authors: Norio
authors: N
authors: Wake
authors: Department of Obstetrics and Gynecology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan. kkato@med.kyushu-u.a.jp.
authors: Kiyoko
authors: K
authors: Kato
mesh_terms: D001665:Binding Sites / Q000235:genetics; D015153:Blotting, Western; D017931:DNA Primers / Q000235:genetics; D016889:Endometrial Neoplasms / Q000235:genetics* / Q000378:metabolism; D005260:Female; D005787:Gene Frequency; D060005:Genotyping Techniques; D006801:Humans; D007150:Immunohistochemistry; D008156:Luciferases; D052002:NF-kappa B p50 Subunit / Q000378:metabolism; D010957:Plasmids / Q000235:genetics; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics*; D051736:Proto-Oncogene Proteins c-mdm2 / Q000235:genetics*
chemical_list: D017931:DNA Primers; D052002:NF-kappa B p50 Subunit; D008156:Luciferases; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2