PURPOSE: The present study investigated in vitro radio-enhancement by gemcitabine (dFdC) in two head and neck squamous cell carcinomas with different intrinsic cellular radiosensitivity. MATERIALS AND METHODS: Radiosensitive (SCC61, SF2=0.16) and radioresistant (SQD9, SF2=0.49) human head and neck squamous cell carcinomas were used. Confluent cells were incubated with dFdC and irradiated in drug-free medium with a single dose of 250 kV X-rays (0-12Gy). Cell survival curves were corrected for the toxicity of the drug alone. RESULTS: In both cell lines, radio-enhancement was observed with 5 microM dFdC incubated for 3 h prior to irradiation. Dose modification factors (DMF) at a surviving fraction level of 0.5 reached 1.3 (95% CI 1.1-1.6) and 1.5 (95% CI 1.4-1.5) for SQD9 and SCC61 cells, respectively. Radio-enhancement was associated with a modest increase in the alpha term of the linear-quadratic model. In SQD9 cells, radio-enhancement increased with dFdC incubation time. At 24h, DMF reached a value of 1.5 (95% CI 0.9-3.2). In SCC61 cells at 24h, DMF reached a value of 1.1 (95% CI 0.9-1.2). In both cell lines, radio-enhancement increased with dFdC concentration up to 5-10 microM from which values it levelled off up to 100 microM. CONCLUSIONS: The data indicated that dFdC induced a modest radio-enhancement in both cell lines. For a short incubation time, dFdC did not radio-enhance preferentially the more radio-resistant cells, whereas the opposite was observed for a longer time. In both cell lines, radio-enhancement was saturated above a dFdC concentration of 5-10 microM.
PURPOSE: The present study investigated in vitro radio-enhancement by gemcitabine (dFdC) in two head and neck squamous cell carcinomas with different intrinsic cellular radiosensitivity. MATERIALS AND METHODS: Radiosensitive (SCC61, SF2=0.16) and radioresistant (SQD9, SF2=0.49) human head and neck squamous cell carcinomas were used. Confluent cells were incubated with dFdC and irradiated in drug-free medium with a single dose of 250 kV X-rays (0-12Gy). Cell survival curves were corrected for the toxicity of the drug alone. RESULTS: In both cell lines, radio-enhancement was observed with 5 microM dFdC incubated for 3 h prior to irradiation. Dose modification factors (DMF) at a surviving fraction level of 0.5 reached 1.3 (95% CI 1.1-1.6) and 1.5 (95% CI 1.4-1.5) for SQD9 and SCC61 cells, respectively. Radio-enhancement was associated with a modest increase in the alpha term of the linear-quadratic model. In SQD9 cells, radio-enhancement increased with dFdC incubation time. At 24h, DMF reached a value of 1.5 (95% CI 0.9-3.2). In SCC61 cells at 24h, DMF reached a value of 1.1 (95% CI 0.9-1.2). In both cell lines, radio-enhancement increased with dFdC concentration up to 5-10 microM from which values it levelled off up to 100 microM. CONCLUSIONS: The data indicated that dFdC induced a modest radio-enhancement in both cell lines. For a short incubation time, dFdC did not radio-enhance preferentially the more radio-resistant cells, whereas the opposite was observed for a longer time. In both cell lines, radio-enhancement was saturated above a dFdC concentration of 5-10 microM.
Authors: Olivier M Vanderveken; Petr Szturz; Pol Specenier; Marco C Merlano; Marco Benasso; Dirk Van Gestel; Kristien Wouters; Carl Van Laer; Danielle Van den Weyngaert; Marc Peeters; Jan Vermorken Journal: Oncologist Date: 2015-12-28
Authors: Natasja Castro Kreder; Chris Van Bree; Nicolaas A P Franken; Jaap Haveman Journal: J Cancer Res Clin Oncol Date: 2003-08-29 Impact factor: 4.553
Authors: A William Blackstock; Joel E Tepper; Donna Niedwiecki; Donna R Hollis; Robert J Mayer; Margaret A Tempero Journal: Int J Gastrointest Cancer Date: 2003
Authors: Bea Pauwels; Annelies E C Korst; Greet G O Pattyn; Hilde A J Lambrechts; Juliette A E Kamphuis; Christel M J De Pooter; Godefridus J Peters; Filip Lardon; Jan B Vermorken Journal: BMC Cancer Date: 2006-05-30 Impact factor: 4.430