title: An aberrant spliced transcript of focal adhesion kinase is exclusively expressed in human breast cancer.
abstract: OBJECTIVE
  To clarify the roles of a new aberrantly spliced transcript of FAK that lacks exon 26 (denoted -26-exon FAK) in human breast cancers.
  
  
  METHODS
  Transcripts of FAK expressed in 102 human breast tumor tissues and 52 corresponding normal tissues were analyzed by RT-PCR and DNA sequencing, as well as agarose gel electrophoresis. The cDNA of -26-exon FAK was cloned and expressed in MCF-10A cells, and then the kinase activity, cellular localization and migration capability of FAK were examined by western blotting, immunofluorescent staining and migration assays, respectively. The expression levels of FAK were analyzed by western blotting in MCF-7 cells treated with TNF-α or in MCF-10A cells upon serum deprivation. The MCF-10A cells transfected with a plasmid expressing -26-exon FAK were cultured in serum-free medium and cell apoptosis was analyzed by flow cytometry.
  
  
  RESULTS
  The -26-exon FAK transcript was exclusively present in human breast tumor tissues and the encoded protein possessed the same kinase activity, cellular localization and cell migration-promoting ability as wild-type FAK. In MCF-7 cells treated with TNF-α, and in MCF-10A cells upon serum deprivation, the -26-exon FAK was resistant to proteolysis while wild-type FAK was largely cleaved. In addition, the -26-exon FAK, but not wild-type FAK, inhibited cell apoptosis.
  
  
  CONCLUSIONS
  The -26-exon FAK transcript, which is exclusively expressed in human breast tumor tissues, encodes a protein that possesses the same kinase activity and biological function as the wild-type FAK, but because it is resistant to the caspase-mediated cleavage that induces the proteolysis of the wild-type form, it ultimately prevents apoptosis.
authors.forename: Ling
authors.initials: L
authors.lastname: Yao
authors.forename: Kai
authors.initials: K
authors.lastname: Li
authors.forename: Wenting
authors.initials: W
authors.lastname: Peng
authors.forename: Qiang
authors.initials: Q
authors.lastname: Lin
authors.forename: Shan
authors.initials: S
authors.lastname: Li
authors.forename: Xin
authors.initials: X
authors.lastname: Hu
authors.forename: Xinmin
authors.initials: X
authors.lastname: Zheng
authors.affiliation: Department of Oncology, Breast Cancer Institute, Shanghai Cancer Center, Shanghai Medical College, Fudan University, No,270, Dong'an Road, Shanghai 200032, People's Republic of China. shaozmyl@126.com.
authors.forename: Zhiming
authors.initials: Z
authors.lastname: Shao
mesh_terms: D001483:Base Sequence; D001943:Breast Neoplasms / Q000201:enzymology* / Q000473:pathology; D045744:Cell Line, Tumor; D002470:Cell Survival; D017931:DNA Primers; D005091:Exons; D005260:Female; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000235:genetics*; D006801:Humans; D059748:Proteolysis; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D017931:DNA Primers; D012333:RNA, Messenger; D051416:Focal Adhesion Protein-Tyrosine Kinases