title: Combination Treatment of Glioblastoma by Low-Dose Radiation and Genistein.
abstract: OBJECTIVE
  Gioblastoma multiforme as a chemoresistant and radioresistant malignant cell line needs to novel strategies to treatment. Low-dose hyper-radiosensitivity (LDHRS) seems to be an effective phenomenon to irradiation that can save normal brain fibroblasts. Genistein which is a soy isoflavone can be cytotoxic in some tumor cell lines. So we determined to study the effect of combining these two treatment modalities.
  
  
  METHODS
  After 30 hours incubation with Genistein in different concentrations on U87MG cell line, proliferation and clonogenicity were conducted by both clonogenic and MTT assays. A conventional 2Gy radiation dose was compared with 10 doses of 0.2Gy gamma irradiation with 3 minutes and 1 hour intervals. Finally, concurrent effect of these modalities was assessed.
  
  
  RESULTS
  Based on acquired cell doubling time (30 hours), one doubling time treatment by Genistein could decrease clonogenicity. U87MG cell line exhibited HRS at low dose irradiations. 2Gy irradiation was more effective than ultra-fractionation methods in comparison with control group. All groups with 50uM concentration of Genistein showed decrease in the survival. This decrease compared with control group, in 10x0.2Gy with 3 minutes intervals plus 50uM Genistein was significant and for groups with the same dose of Genistein but along with continuous 2Gy was more significant.
  
  
  CONCLUSIONS
  In one day treatment regimen, 10x0.2Gy ultra-fractionation with 3 minutes and 1 hour intervals seems to be less effective than conventional 2Gy irradiation, however adding 50uM Genistein can decrease survival more. Although 2Gy conventional dose plus 50uM Genistein was the most effective regimen.
authors.forename: Zamanian
authors.initials: Z
authors.lastname: Atefeh
authors.affiliation: Department of Technology of Radiology and Radiotherapy, Allied Medical Sciences School, Tehran University of Medical Sciences, No:17, Faredanesh Alley, Ghods Ave, BLW Keshavarz, Tehran, Iran.
authors.forename: Changizi
authors.initials: C
authors.lastname: Vahid
authors.forename: Nedaie
authors.initials: N
authors.lastname: Hasan
authors.forename: Amanpour
authors.initials: A
authors.lastname: Saeed
authors.forename: Haddadi
authors.initials: H
authors.lastname: Mahnaz
mesh_terms: D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D003131:Combined Modality Therapy; D004797:Enzyme-Linked Immunosorbent Assay; D019833:Genistein / Q000494:pharmacology*; D005909:Glioblastoma / Q000188:drug therapy* / Q000532:radiotherapy*; D006801:Humans; D066298:In Vitro Techniques; D011879:Radiotherapy Dosage
chemical_list: D016588:Anticarcinogenic Agents; D019833:Genistein
keywords: Fractionated radiotherapy; GBM; HRS; IRR; Low-dose Hyper-radiosensitivity.; genistein; glioblastoma