Journal of Nucleic Acids

Research Article

Modulation of the Ribonucleotide Reductase-Antimetabolite Drug Interaction in Cancer Cell Lines

Table 2

Impact of RRM1 expression on drug combinations. ∗
Drug combinationClones of H23
H23-CtH23-R1H23-shCtH23-shR1
controlR1 increasedcontrolR1 decreased
Gemcitabine & Carboplatin0.93 ( + / − )0.83 ( + + )0.56 ( + + + )0.72 ( + + )
Gemcitabine & Docetaxel2.8 ( − − − )2.1 ( − − − )3.1 ( − − − )1.4 ( − − )
Gemcitabine & Pemetrexed1.5 ( − − − )1.4 ( − − )1.7 ( − − − )1.7 ( − − − )
Pemetrexed & Carboplatin0.79 ( + + )0.94 ( + / − )0.73 ( + + )0.64 ( + + + )
∗ The combination index (CI) was calculated according to Chou [10] and averaged from three separate experiments. Combination indices C I < 1 , C I = 1 , and C I > 1 indicate synergism, additive effects, and antagonism, respectively. Ranking symbols within parenthesis indicate relative antagonism, additivity, or synergy: ( − − − : strong antagonism; − − : moderate antagonism; + / − : nearly additive; + + : moderate synergy; + + + : strong synergy).