title: Cancer cell sensitivity to bortezomib is associated with survivin expression and p53 status but not cancer cell types.
abstract: BACKGROUND
  Survivin is known playing a role in drug resistance. However, its role in bortezomib-mediated inhibition of growth and induction of apoptosis is unclear. There are conflicting reports for the effect of bortezomib on survivin expression, which lacks of a plausible explanation.
  
  
  METHODS
  In this study, we tested cancer cells with both p53 wild type and mutant/null background for the relationship of bortezomib resistance with survivin expression and p53 status using MTT assay, flow cytometry, DNA fragmentation, caspase activation, western blots and RNAi technology.
  
  
  RESULTS
  We found that cancer cells with wild type p53 show a low level expression of survivin and are sensitive to treatment with bortezomib, while cancer cells with a mutant or null p53 show a high level expression of survivin and are resistant to bortezomib-mediated apoptosis induction. However, silencing of survivin expression utilizing survivin mRNA-specific siRNA/shRNA in p53 mutant or null cells sensitized cancer cells to bortezomib mediated apoptosis induction, suggesting a role for survivin in bortezomib resistance. We further noted that modulation of survivin expression by bortezomib is dependent on p53 status but independent of cancer cell types. In cancer cells with mutated p53 or p53 null, bortezomib appears to induce survivin expression, while in cancer cells with wild type p53, bortezomib downregulates or shows no significant effect on survivin expression, which is dependent on the drug concentration, cell line and exposure time.
  
  
  CONCLUSIONS
  Our findings, for the first time, unify the current inconsistent findings for bortezomib treatment and survivin expression, and linked the effect of bortezomib on survivin expression, apoptosis induction and bortezomib resistance in the relationship with p53 status, which is independent of cancer cell types. Further mechanistic studies along with this line may impact the optimal clinical application of bortezomib in solid cancer therapeutics.
authors.affiliation: Departments of Pharmacology & Therapeutics, Roswell Park Cancer Institute, Buffalo, New York 14263, USA.
authors.forename: Xiang
authors.initials: X
authors.lastname: Ling
authors.forename: Diane
authors.initials: D
authors.lastname: Calinski
authors.forename: Asher A
authors.initials: AA
authors.lastname: Chanan-Khan
authors.forename: Muxiang
authors.initials: M
authors.lastname: Zhou
authors.forename: Fengzhi
authors.initials: F
authors.lastname: Li
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D001897:Boronic Acids / Q000627:therapeutic use*; D000069286:Bortezomib; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D016158:Genes, p53; D045325:HCT116 Cells; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D009369:Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000378:metabolism*; D011719:Pyrazines / Q000627:therapeutic use*; D034741:RNA, Small Interfering / Q000494:pharmacology; D000077022:Survivin
chemical_list: C107489:BIRC5 protein, human; D001897:Boronic Acids; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins; D011719:Pyrazines; D034741:RNA, Small Interfering; D000077022:Survivin; D000069286:Bortezomib