Supplementary Figure S1. Phenothiazines enhance DNA damage-induced killing of
human lung cancer cells. Clonogenic capacity was determined for U1810 and H23 cells
exposed to DNA damaging agents alone or in combination with a phenothiazine (10 μM). (a)
TFP significantly enhanced the cytotoxicity of bleomycin in H23 cells. (b) TFP significantly
potentiated the cytotoxicity of cisplatin in H23 cells. (c) FPZ and TFPZ significantly
potentiated the cytotoxicity of cisplatin in U1810 cells. For (a), mean and S.D. were compiled
from two-three independent experiments performed in duplicates (* P<0.05, co-treatment
versus single-agent bleo/cis treatment). For (b, c), mean was compiled from two independent
experiments performed in duplicates.
Supplementary Figure S2. TFP delays the recovery of U1810 cells from DNA damageinduced checkpoints. Cells were exposed to DNA damaging drugs (2.5 μg/ml bleomycin, 20
μM cisplatin) alone or in combination with TFP (10 μM). At indicated time points, cell cycle
distribution was determined by DNA content analysis. Same as Figure 3, but also includes the
data for mock-treated cells and cells treated with TFP alone. (a) TFP significantly delayed the
recovery of cells from bleomycin-induced G2-M checkpoint arrest. (b) TFP significantly
delayed the recovery of cell from cisplatin-induced intra-S checkpoint arrest.
Supplementary Figure S3. TFP co-treatment was associated with increased activation of
both the extrinsic and the intrinsic apoptotic pathways. U1810 cells were exposed to DNA
damaging drugs (2.5 μg/ml bleomycin, 20 μM cisplatin)) alone or in combination with TFP
(10 μM). (a) TFP co-treatment enhanced the conformational activation of Bak and Bax. (b)
TFP increased mitochondrial depolarization in bleomycin- or cisplatin-treated cells in a timedependent manner. (c) TFP enhanced the cleavage of caspase-8 in cisplatin-treated cells; for
immunoblotting, samples were collected 48 h post DNA damaging treatment. For (a, b), mean
and S.D. were compiled from at least three independent experiments performed in duplicates
(* P<0.05, TFP co-treatment versus single-agent bleo/cis treatment). For (c), the numbers at
the top indicate the normalized intensity of the bands. One representative experiment is shown
(n=3).