title: Comparison of the sulforhodamine B assay and the clonogenic assay for in vitro chemoradiation studies.
abstract: OBJECTIVE
  Since there is a growing interest in preclinical research on interactions between radiation and cytotoxic agents, this study focused on the development of an alternative to the very laborious clonogenic assay (CA).
  
  
  METHODS
  The colorimetric sulforhodamine B (SRB) assay was compared to the clonogenic assay for radiosensitivity testing in two lung cancer cell lines (A549, H292), one colon cancer cell line (HT-29) and one breast cancer cell line (MCF-7). In addition, the combination of the radiosensitizing agent gemcitabine and radiation was investigated with both assays.
  
  
  RESULTS
  The dose-response curves obtained with the SRB assay and the CA were very similar up to 6 Gy. The radiosensitivity parameters (SF(2), alpha, beta, MID and ID(50)) obtained from the SRB assay and the CA were not significantly different between H292, A549 and MCF-7 cells. The radiation dose-response curves for A549 and H292 cells pretreated with 4 n M gemcitabine for 24 h clearly showed a radiosensitizing effect with both assays. The dose-enhancement factors obtained with the SRB assay and the CA were 1.80 and 1.76, respectively, for A549 cells, and 1.52 and 1.41 for H292 cells.
  
  
  CONCLUSIONS
  The SRB assay was shown to be as useful as the more traditional CA for research on chemotherapy/radiotherapy interactions in cell lines with moderate radiosensitivity. This assay will be used for more extensive in vitro research on radiosensitizing compounds in these cell lines.
authors.affiliation: Department of Medical Oncology, University of Antwerp (UIA/UZA), Universiteitsplein 1, 2610, Wilrijk, Belgium. bea.pauwels@ua.ac.be
authors.forename: Bea
authors.initials: B
authors.lastname: Pauwels
authors.forename: Annelies E C
authors.initials: AE
authors.lastname: Korst
authors.forename: Christel M J
authors.initials: CM
authors.lastname: de Pooter
authors.forename: Greet G O
authors.initials: GG
authors.lastname: Pattyn
authors.forename: Hilde A J
authors.initials: HA
authors.lastname: Lambrechts
authors.forename: Marc F D
authors.initials: MF
authors.lastname: Baay
authors.forename: Filip
authors.initials: F
authors.lastname: Lardon
authors.forename: Jan B
authors.initials: JB
authors.lastname: Vermorken
mesh_terms: D001943:Breast Neoplasms / Q000473:pathology; D003110:Colonic Neoplasms / Q000473:pathology; D003114:Colony-Forming Units Assay / Q000379:methods*; D003124:Colorimetry; D003131:Combined Modality Therapy; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D005456:Fluorescent Dyes; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*; D011878:Radiotherapy; D012235:Rhodamines; D012680:Sensitivity and Specificity; D014407:Tumor Cells, Cultured; D000093542:Gemcitabine
chemical_list: D005456:Fluorescent Dyes; D011838:Radiation-Sensitizing Agents; D012235:Rhodamines; D003841:Deoxycytidine; C022027:lissamine rhodamine B; D000093542:Gemcitabine