title: Identification of a novel prostate cancer-associated tumor antigen.
abstract: BACKGROUND
  The identification of antigens that distinguish cancer cells from normal cells is of major importance for the definition of therapeutic targets in human malignancies. Using sera from cancer patients, we have previously reported on the identification of immunologically recognized proteins that belong to the family of cancer testis antigens (CTAs).
  
  
  METHODS
  A normal testicular cDNA library was screened with pooled allogeneic sera from patients with prostate cancer using a modified SEREX approach. Subsequently we have identified and characterized a novel antigen, T21, with an expression pattern similar to that of CTAs. mRNA expression of T21 was determined using a panel of whole tissues and prostate cell lines using Q-RT-PCR. For laser microdissection, fresh prostate cancer and benign tissue was obtained using our novel validated harvesting technique. Protein expression and cellular localization of T21 were assessed in prostate cell lines using Western blotting, confocal microscopy and flow cytometry.
  
  
  RESULTS
  T21 showed tissue-restricted mRNA expression in gastric, kidney and prostate cancers, and in normal testis and prostate tissues. Following laser microdissection, T21 was significantly over-expressed in malignant compared to benign prostatic epithelium. We have demonstrated expression of T21 at the protein level and confocal microscopy on PC3 cells probed with a T21-monospecific antibody revealed cytoplasmic localization of T21 protein.
  
  
  CONCLUSIONS
  The highly restricted expression pattern of T21 makes it an attractive vaccine target for prostate cancer. Several CTAs reportedly induce cytotoxic T-lymphocyte responses, therefore it is reasonable to assume that T21 will be a valuable target for cancer immunotherapy.
authors.affiliation: School of Biomedical and Natural Science, Nottingham Trent University, Clifton Lane, Clifton, Nottingham, United Kingdom.
authors.forename: Amanda K
authors.initials: AK
authors.lastname: Miles
authors.forename: Alistair
authors.initials: A
authors.lastname: Rogers
authors.forename: Geng
authors.initials: G
authors.lastname: Li
authors.forename: Rashmi
authors.initials: R
authors.lastname: Seth
authors.forename: Des
authors.initials: D
authors.lastname: Powe
authors.forename: Stephanie E B
authors.initials: SE
authors.lastname: McArdle
authors.forename: Thomas A
authors.initials: TA
authors.lastname: McCulloch
authors.forename: Michael C
authors.initials: MC
authors.lastname: Bishop
authors.forename: Robert C
authors.initials: RC
authors.lastname: Rees
mesh_terms: D000293:Adolescent; D000328:Adult; D000595:Amino Acid Sequence; D000951:Antigens, Neoplasm / Q000097:blood* / Q000235:genetics / Q000276:immunology; D001483:Base Sequence; D015153:Blotting, Western; D045744:Cell Line, Tumor; D002648:Child; D018076:DNA, Complementary / Q000096:biosynthesis / Q000235:genetics; D005091:Exons; D015723:Gene Library; D006801:Humans; D007438:Introns; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D011471:Prostatic Neoplasms / Q000097:blood / Q000235:genetics / Q000276:immunology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012334:RNA, Neoplasm / Q000737:chemistry / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D000951:Antigens, Neoplasm; D018076:DNA, Complementary; D012333:RNA, Messenger; D012334:RNA, Neoplasm