title: RAIDD expression is impaired in multidrug resistant osteosarcoma cell lines.
abstract: OBJECTIVE
  To identify the apoptosis genes involved in the multidrug resistant phenotype of osteosarcoma.
  
  
  METHODS
  Multidrug resistant human osteosarcoma cell line (U-2 OS MR) and a drug sensitive parental cell line (U-2 OS) were both treated with paclitaxel and analyzed by the gene array containing 96 apoptosis associated genes. The different expression of the special apoptosis associated genes were further analyzed by Western blot in the multidrug resistant osteosarcoma cell lines (U-2 OS MR, KH OS R2) and the drug sensitive parental cell lines (U-2 OS, KH OS). One of the disregulated gene, RAIDD, was transfected into the multidrug resistant osteosarcoma cells for functional studies.
  
  
  RESULTS
  RAIDD showed signs of significant expression in the U-2 OS cells after being treated with paclitaxel (P < 0.01). However, the induction of RAIDD did not occur in U-2 OS MR cells (P = 0.2). Subsequent analysis by Western blot confirmed the deficiency of the expression of RAIDD protein in U-2 OS MR. On the contrary, the expression of RAIDD could be significantly induced by paclitaxel and doxorubicin in U-2 OS cells as both time and dosage were deciding factors. It also demonstrated the cleavage of PARP associated with RAIDD expression in U-2 OS cells, but not however in U-2 OS MR cells after being treated with paclitaxel or doxorubicin. Similar results were found in osteosarcoma multidrug resistant cell line KH OS R2 and the drug sensitive parental cell line KH OS. Furthermore, over-expression of RAIDD in multidrug resistant cell lines could possibly reverse drug resistant phenotypes.
  
  
  CONCLUSIONS
  This study indicate that impaired expression of RAIDD in drug induced apoptosis may play a role in the multidrug resistance of osteosarcoma cells.
authors.affiliation: Department of Orthopaedic Surgery, Massachusetts General Hospital, Boston, MA 02114, USA.
authors.forename: Cao
authors.initials: C
authors.lastname: Yang
authors.forename: Francis J
authors.initials: FJ
authors.lastname: Hornicek
authors.forename: Kirkham B
authors.initials: KB
authors.lastname: Wood
authors.forename: Joseph H
authors.initials: JH
authors.lastname: Schwab
authors.forename: Henry
authors.initials: H
authors.lastname: Mankin
authors.forename: Zhenfeng
authors.initials: Z
authors.lastname: Duan
mesh_terms: D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D000972:Antineoplastic Agents, Phytogenic / Q000008:administration & dosage / Q000494:pharmacology; D017209:Apoptosis / Q000235:genetics*; D015153:Blotting, Western; D053420:CRADD Signaling Adaptor Protein / Q000235:genetics*; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000494:pharmacology; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D012516:Osteosarcoma / Q000235:genetics*; D017239:Paclitaxel / Q000008:administration & dosage / Q000494:pharmacology; D010641:Phenotype; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D013997:Time Factors; D014162:Transfection
chemical_list: D000903:Antibiotics, Antineoplastic; D000972:Antineoplastic Agents, Phytogenic; D053420:CRADD Signaling Adaptor Protein; C104252:CRADD protein, human; D004317:Doxorubicin; D011065:Poly(ADP-ribose) Polymerases; D017239:Paclitaxel