title: Decreased therapeutic effects of noscapine combined with imatinib mesylate on human glioblastoma in vitro and the effect of midkine.
abstract: BACKGROUND
  Glioblastoma (GBM) develops resistance to the advances in chemotherapy leading to poor prognosis and life quality. Consequently, new treatment modalities are needed. Our aims were to investigate the effects of combined noscapine (NOS) and imatinib mesylate (IM) on human GBM in vitro and the role of midkine (MK) in this new combination treatment.
  
  
  METHODS
  Monolayer and spheroid cultures of T98G human GBM cell line were used to evaluate the effects of IM (10 μM), Nos (10 μM) and their combination on cell proliferation and apoptotic indexes, cell cycle, the levels of antiapoptotic MK, MRP-1, p170, PFGFR-α, EGFR, bcl-2 proteins, apoptotic caspase-3 levels, morphology (SEM) and ultrastructure (TEM) for 72 hrs. Results were statistically analyzed using the Student's t-test.
  
  
  RESULTS
  The combination group induced highest decrease in cell proliferation and apoptotic indexes, caspase-3 levels, MRP-1 and PDGFR-α levels. The decrease in p170 levels were lower than IM but higher that NOS. The highest increases were in EGFR, MK, bcl-2 and cAMP levels in the combination group. The G0+G1 cell cycle arrest at the end of 72nd hr was the lowest in the combination group. Apoptotic appearence was observed rarely both in the morphologic and ultrastructural evaluation of the combination group. In addition, autophagic vacuoles which were frequently observed in the IM group were observed rarely.
  
  
  CONCLUSIONS
  The combination of Nos with IM showed antagonist effect in T98G human GBM cells in vitro. This antagonist effect was correlated highly with MK levels. The effects of NOS on MRP-1, MK and receptor tyrosine kinase levels were firstly demonstrated in our report. In addition, we proposed that MK is one of the modulator in the switch of autophagy to cell death or survival/resistance.
authors.affiliation: Yeni Yüzyıl University, Faculty of Medicine, Department of Biochemistry, Istanbul, Turkey. mine.erguven@gmail.com.
authors.forename: Mine
authors.initials: M
authors.lastname: Erguven
authors.forename: Ayhan
authors.initials: A
authors.lastname: Bilir
authors.forename: Nuray
authors.initials: N
authors.lastname: Yazihan
authors.forename: Ezgi
authors.initials: E
authors.lastname: Ermis
authors.forename: Akin
authors.initials: A
authors.lastname: Sabanci
authors.forename: Esin
authors.initials: E
authors.lastname: Aktas
authors.forename: Yavuz
authors.initials: Y
authors.lastname: Aras
authors.forename: Vehbi
authors.initials: V
authors.lastname: Alpman