title: Co-overexpression of Bag-1 and heat shock protein 70 in human epidermal squamous cell carcinoma: Bag-1-mediated resistance to 5-fluorouracil-induced apoptosis.
abstract: BACKGROUND
  The aim was to determine whether Bcl-2-associated athanogene-1 (Bag-1) and/or its binding protein heat shock protein-70 (Hsp70) exhibit deregulated expression in epidermal squamous cell carcinoma (SCC) and whether Bag-1 confers apoptosis resistance.
  
  
  METHODS
  Immunohistochemistry for Bag-1 and Hsp70 was performed on 60 epidermal SCC and 10 normal skin samples. The epidermal SCC cell line SCC-13 was treated with 5-fluorouracil (5-FU) after Bag-1 knockdown to determine whether high Bag-1 levels contribute to growth and/or apoptosis resistance.
  
  
  RESULTS
  Normal epithelium expressed primarily nuclear Bag-1. Most tumours showed reduced nuclear Bag-1 staining, but a subset exhibited strong Bag-1 staining, with cytoplasmic Bag-1 staining intensity correlating with cytoplasmic Hsp70 staining intensity (r(s)=0.462; P<0.001) and less differentiation (P<0.001). Bag-1 knockdown resulted in markedly reduced SCC-13 cell yield, increased spontaneous apoptosis and enhanced sensitivity to 5-FU-induced apoptosis. Apoptosis induced by 5-FU in the Bag-1-knockdown cells was significantly greater than the additive apoptotic effect of 5-FU or Bag-1 knockdown alone.
  
  
  CONCLUSIONS
  Overexpression of Bag-1 and Hsp70 in poorly differentiated SCC may confer both enhanced tumour cell growth and apoptosis resistance. Bag-1 may contribute to the resistance of more advanced epidermal SCC to chemotherapy.
authors.affiliation: School of Oral and Dental Science, University of Bristol, Lower Maudlin Street, Bristol BS1 2LY, UK.
authors.forename: J
authors.initials: J
authors.lastname: Wood
authors.forename: M
authors.initials: M
authors.lastname: Pring
authors.forename: J W
authors.initials: JW
authors.lastname: Eveson
authors.forename: N
authors.initials: N
authors.lastname: Price
authors.forename: C M
authors.initials: CM
authors.lastname: Proby
authors.forename: A
authors.initials: A
authors.lastname: Hague
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D005472:Fluorouracil / Q000494:pharmacology*; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D015603:Keratinocytes / Q000378:metabolism; D034741:RNA, Small Interfering; D012867:Skin / Q000378:metabolism; D012878:Skin Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D000964:Antimetabolites, Antineoplastic; C091732:BCL2-associated athanogene 1 protein; D004268:DNA-Binding Proteins; D018840:HSP70 Heat-Shock Proteins; D034741:RNA, Small Interfering; D014157:Transcription Factors; D005472:Fluorouracil