title: A microarray-based gene expression analysis to identify diagnostic biomarkers for unknown primary cancer.
abstract: BACKGROUND
  The biological basis for cancer of unknown primary (CUP) at the molecular level remains largely unknown, with no evidence of whether a common biological entity exists. Here, we assessed the possibility of identifying a common diagnostic biomarker for CUP using a microarray gene expression analysis.
  
  
  METHODS
  Tumor mRNA samples from 60 patients with CUP were analyzed using the Affymetrix U133A Plus 2.0 GeneChip and were normalized by asinh (hyperbolic arc sine) transformation to construct a mean gene-expression profile specific to CUP. A gene-expression profile specific to non-CUP group was constructed using publicly available raw microarray datasets. The t-tests were performed to compare the CUP with non-CUP groups and the top 59 CUP specific genes with the highest fold change were selected (p-value<0.001).
  
  
  RESULTS
  Among the 44 genes that were up-regulated in the CUP group, 6 genes for ribosomal proteins were identified. Two of these genes (RPS7 and RPL11) are known to be involved in the Mdm2-p53 pathway. We also identified several genes related to metastasis and apoptosis, suggesting a biological attribute of CUP.
  
  
  CONCLUSIONS
  The protein products of the up-regulated and down-regulated genes identified in this study may be clinically useful as unique biomarkers for CUP.
authors.affiliation: Department of Planning, Information, and Management, University of Tokyo, Tokyo, Japan.
authors.forename: Issei
authors.initials: I
authors.lastname: Kurahashi
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Fujita
authors.forename: Tokuzo
authors.initials: T
authors.lastname: Arao
authors.forename: Takayasu
authors.initials: T
authors.lastname: Kurata
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Koh
authors.forename: Kazuko
authors.initials: K
authors.lastname: Sakai
authors.forename: Koji
authors.initials: K
authors.lastname: Matsumoto
authors.forename: Maki
authors.initials: M
authors.lastname: Tanioka
authors.forename: Koji
authors.initials: K
authors.lastname: Takeda
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Takiguchi
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Yamamoto
authors.forename: Asuka
authors.initials: A
authors.lastname: Tsuya
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Matsubara
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Mukai
authors.forename: Hironobu
authors.initials: H
authors.lastname: Minami
authors.forename: Naoko
authors.initials: N
authors.lastname: Chayahara
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Yamanaka
authors.forename: Keisuke
authors.initials: K
authors.lastname: Miwa
authors.forename: Shin
authors.initials: S
authors.lastname: Takahashi
authors.forename: Shunji
authors.initials: S
authors.lastname: Takahashi
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Nakagawa
authors.forename: Kazuto
authors.initials: K
authors.lastname: Nishio
mesh_terms: D014408:Biomarkers, Tumor / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D016000:Cluster Analysis; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D009382:Neoplasms, Unknown Primary / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods*; D015854:Up-Regulation
chemical_list: D014408:Biomarkers, Tumor