Research Article

Inhibition of NF-κB by Dehydroxymethylepoxyquinomicin Suppresses Invasion and Synergistically Potentiates Temozolomide and γ-Radiation Cytotoxicity in Glioblastoma Cells

Table 2

Median dose effect analysis was also employed to characterize the interactions between DHMEQ and TMZ. For concomitant treatment, different doses of DHMEQ were combined with 250 μM TMZ and treated for 48 h. For the sequential schedule cells were exposed to different concentrations of DHMEQ, and after 6 h TMZ at the same dose was included in culture media and also analyzed at 48 h (TMZ exposure 42 h). Combination index (CI) values <1 correspond to a synergistic interaction (emphasized in bold). Dose reduction index (DRI) reflects the fold reduction in the required concentration of tested agents when used in combination to achieve the comparable affected fraction (AF).

U251Concomitant TMZ (250 μM)Sequential TMZ (250 μM)
DHMEQ (μg/mL)AFAFCI DRIAFCI DRI

2.50.000.152.020.580.380.681.87
50.070.261.311.110.420.732.19
100.190.361.211.730.60.594.36
200.470.650.835.330.80.5110.99

U343MG-aConcomitant TMZ (250 μM)Sequential TMZ (250 μM)
DHMEQ (μg/mL)AFAFCI DRIAFCI DRI

2.50.080.370.81.560.261.171.08
50.100.440.781.920.410.861.76
100.220.580.692.860.580.692.86
200.530.790.475.840.800.456.10

U138MGConcomitant TMZ (250 μM)Sequential TMZ (250 μM)
DHMEQ (μg/mL)AFAFCI DRIAFCI DRI

2.50.010.014.220.310.180.482.07
50.010.012.080.480.260.362.76
100.030.021.600.620.340.283.50
200.020.021.103.030.850.0615.25

U87MGConcomitant TMZ (250 μM)Sequential TMZ (250 μM)
DHMEQ (μg/mL)AFAFCI DRIAFCI DRI

2.50.000.530.37.10.420.612.42
50.100.450.683.260.610.3415.71
100.270.600.6414.20.830.33248.40
200.690.880.55666.160.940.384197.79

T98GConcomitant TMZ (250 μM)Sequential TMZ (250 μM)
DHMEQ (μg/mL)AFAFCI DRIAFCI DRI

2.50.050.0253.870.010.261.001.20
50.110.087.580.150.360.702.39
100.180.134.520.60.390.852.88
200.430.321.840.760.820.2250.10

LN319Concomitant TMZ (250 μM)Sequential TMZ (250 μM)
DHMEQ (μg/mL)AFAFCI DRIAFCI DRI

2.50.090.410.374.370.440.335.1
50.250.550.38.900.340.682.74
100.440.70.2720.090.890.0996.11
200.670.80.3139.60.880.1984.93