title: Missense allele of a single nucleotide polymorphism rs2294008 attenuated antitumor effects of prostate stem cell antigen in gallbladder cancer cells.
abstract: 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.
  
  
  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.
authors.affiliation: Division of Genetics, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo, Japan.
authors.forename: Hiroe
authors.initials: H
authors.lastname: Ono
authors.forename: Dai
authors.initials: D
authors.lastname: Chihara
authors.forename: Fumiko
authors.initials: F
authors.lastname: Chiwaki
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Yanagihara
authors.forename: Hiroki
authors.initials: H
authors.lastname: Sasaki
authors.forename: Hiromi
authors.initials: H
authors.lastname: Sakamoto
authors.forename: Hideo
authors.initials: H
authors.lastname: Tanaka
authors.forename: Teruhiko
authors.initials: T
authors.lastname: Yoshida
authors.forename: Norihisa
authors.initials: N
authors.lastname: Saeki
authors.forename: Keitaro
authors.initials: K
authors.lastname: Matsuo
keywords: Association study; cancer susceptibility; gallbladder cancer; missense single nucleotide polymorphism; tumor suppressor