title: Reversal of stathmin-mediated microtubule destabilization sensitizes retinoblastoma cells to a low dose of antimicrotubule agents: a novel synergistic therapeutic intervention.
abstract: OBJECTIVE
  To explore the possibility of stathmin as an effective therapeutic target and to evaluate the synergistic combination of stathmin RNAi and the antimicrotubule agents paclitaxel and vincristine to retinoblastoma Y79 cells.
  
  
  METHODS
  RNAi-mediated specific inhibition of stathmin expression in Y79 cells was shown by real-time quantitative RT-PCR (RT-Q-PCR), its effect on cell proliferation by MTT assay, cell invasion using matrigel, microtubule polymerization by immunohistochemistry, apoptosis, cell cycle analysis by flow cytometry analysis, and the changes in FOXM1 protein expression were studied by Western blot. The effect of combination treatment of stathmin siRNA and paclitaxel/vincristine was studied by assessing cell viability and apoptosis.
  
  
  RESULTS
  Short interfering RNA-mediated transient stathmin downregulation resulted in a marked inhibition of retinoblastoma cell proliferation and cell invasion in vitro. Stathmin inhibition promoted Y79 cells to G2/M phase, and ultimately there were increased apoptotic events as evidenced by higher caspase-3 activation and cleaved poly(ADP-ribose) polymerase expression. Cells transfected with stathmin siRNA showed long and bundled microtubule polymers and sensitized the Y79 cells significantly to paclitaxel and vincristine.
  
  
  CONCLUSIONS
  Stathmin may be a pivotal determinant for retinoblastoma tumorigenesis and chemosensitivity. Strategies to inhibit stathmin will help to enhance the cytotoxic effect of paclitaxel while reducing toxicity (or side effects) to normal cells caused by high doses.
authors.affiliation: Department of Ocular Pathology, Vision Research Foundation, Sankara Nethralaya, Tamil Nadu, India.
authors.forename: Moutushy
authors.initials: M
authors.lastname: Mitra
authors.forename: Mallikarjuna
authors.initials: M
authors.lastname: Kandalam
authors.forename: Curam S
authors.initials: CS
authors.lastname: Sundaram
authors.forename: Rama Shenkar
authors.initials: RS
authors.lastname: Verma
authors.forename: Uma K
authors.initials: UK
authors.lastname: Maheswari
authors.forename: Sethuraman
authors.initials: S
authors.lastname: Swaminathan
authors.forename: Subramanian
authors.initials: S
authors.lastname: Krishnakumar
mesh_terms: D017209:Apoptosis; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D002453:Cell Cycle; D049109:Cell Proliferation; D002470:Cell Survival; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D005786:Gene Expression Regulation / Q000187:drug effects*; D020868:Gene Silencing / Q000187:drug effects; D006801:Humans; D008870:Microtubules / Q000187:drug effects* / Q000378:metabolism; D008940:Mitotic Index; D017239:Paclitaxel / Q000494:pharmacology; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D019572:Retinal Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D012175:Retinoblastoma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050777:Stathmin / Q000235:genetics*; D014162:Transfection; D050257:Tubulin Modulators / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D014750:Vincristine / Q000494:pharmacology
chemical_list: D012333:RNA, Messenger; D034741:RNA, Small Interfering; D050777:Stathmin; D050257:Tubulin Modulators; D014750:Vincristine; D011065:Poly(ADP-ribose) Polymerases; D053148:Caspase 3; D017239:Paclitaxel