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. 2009 May 12;17(8):1355–1364. doi: 10.1038/mt.2009.103

Figure 4.

Figure 4

A combination of TK expression driven by the reactive oxygen species-responsive chimeric promoter, and GCV, with g radiation, Bleo, or Dx, enhances in vitro cell growth inhibition. (a) LoVo and A375N cells were transiently transfected with E6(40)VE-TK and exposed to g radiation in the presence or absence of 10 µmol/l GCV (***P < 0.001, **P < 0.01). (b) LoVo and A375N cells were transiently transfected with E6(40)VE-TK and exposed to Dx (0.5 µmol/l), or Bleo (20 µmol/l), in the presence or absence of 10 or 50 µmol/l GCV. Growth inhibition was measured by the MTT assay and “growth fraction” refers to the inhibition seen in comparison with untreated cells (***P < 0.001). (c) Spheroids made of LoVo or A375N cells, transiently transfected with E6(40)VE-TK, were exposed to GCV (50 µmol/l), Dx (0.5 µmol/l), or both. Spheroid growth was measured using the MTT assay. Data show the mean ± SD of three to five measurements within a representative experiment of two experiments. Each measurement includes one spheroid of A375N cells and a pool of three spheroids for LoVo cells. Inset: photomicrographs (×25) of spheroids taken at day 20 (*P < 0.05 and **P < 0.01). Data show the means ± SD values of three independent experiments and lines over the bars indicate the groups that were compared. Bleo, bleomycin; C, control; Dx, doxorubicin; GCV, gancyclovir; PBS, phosphate buffered saline; TK, thymidine kinase.