Fig. 1

Chemosensitivity in HCC cells is associated with drug-induced increases in NHEJ activity. a Following conventional therapy regimens with the drugs cisplatin (cis), oxaliplatin (oxa) doxorubicin (dox), as well as treatment with 5-FU, DSB foci in PLC and 97 L cells were localized using an anti-γH2AX antibody. b Quantification of the percentage of γH2AX foci-positive cells. Data are reported as the mean ± SD from 2 independent experiments. c Statistical comparison of the percentage of γH2AX-positive cells between PLC and 97 L groups at 9 h and 48 h after drug treatment. A total of 1000 cells were randomly selected for counting. The mean ± SD was from 3 independent experiments. p values ≤0.05 and ≤0.01 were denoted as * and **, respectively. d In vitro NHEJ activity was assayed after oxaliplatin and doxorubicin treatment and quantified by plasmid-based quantitative PCR (see methods). NHEJ activity from 3 independent experiments was statistically analyzed using a paired Student’s t test. e HCC cells were transfected with the plasmid pEGFP-PEM1-Ad2, followed by drug treatment. In vivo NHEJ activity was calculated based on the frequency of GFP-positive cells normalized to the transfection efficiency. Drug-induced NHEJ activity was counted as a ratio of drug-induced activity versus control activity. Representative data are reported as the mean ± SD, n = 3. f PLC and 97 L cells were treated with cisplatin (1 μg/ml), oxaliplatin (1 μg/ml), or doxorubicin (0.2 μg/ml). Cell viability (%) was determined using a Cell Counting Kit 8 and standardized against cells without drug treatment. Representative data are reported as the mean ± SD, n = 3. g The therapy drug (oxaliplatin) response curve and the IC50 concentration for the PLC and 97 L cells were analyzed from 2 independent experiments using GraphPad 6.0