Fig. 6

Stimulation of γ-H2AX foci resolution with L-lactate, D-lactate and 3,5-dihydroxybenzoic acid (3,5-DHBA) in cells treated with neocarzinostatin is compromised by pertussis toxin pretreatment. HeLa cells were incubated in the presence or absence of 500 μM 3,5-DHBA, 20 mM L-lactate or 20 mM D-lactate for 24 h, followed by treatment with 2 nM NCS for 30 min. Then, the cells were allowed to recover for 4 h unless otherwise indicated. a γ-H2AX foci resolution kinetics after 3,5-DHBA treatment. The graphs show the mean number of γ-H2AX foci per cell ± SEM from at least three independent experiments; drug alone (white circles), 3,5-DHBA + drug (black circles). b DSB repair after NCS treatment was measured by a neutral comet assay. HeLa cells were incubated in the presence or absence of 3,5-DHBA for 24 h, followed by treatment with 5 nM NCS for 30 min. Then, the cells were allowed to recover for 2 h. The basal Olive tail moment (OTM) was subtracted, and the value observed at 0 h was set to 100 %. The graph shows the mean OTM (% of control) ± SEM from three independent experiments. c, d, e γ-H2AX foci resolution in HeLa cells pretreated with 100 ng/ml PTX for 1 h before incubation in the presence or absence of 3,5-DHBA (c), L-lactate (d) or D-lactate (e). The graphs show the mean number of γ-H2AX foci per cell expressed as a % of control ± SEM from at least three independent experiments. Statistical significance was evaluated using Student’s t-test. *P < 0.05 and **P < 0.01 indicate significant differences compared to the untreated cells