Glycogen synthase kinase 3β inhibition synergizes with PARP inhibitors through the induction of homologous recombination deficiency in colorectal cancer

摘要

A Heatmap representation of the efficacy of drug combinations. Screening of drug combinations was performed in BRCA1-deficient HCC1937 and BRCA2-deficient HCT-15 cells. Prior to screening, olaparib (OP) and niraparib (NP) were arrayed in 96-well plates and serially diluted 2-fold, and Sulforhodamine B (SRB) assay was used to analyze cytotoxicity to obtain a concentration that was 20% of the inhibition rate (IR). Data pertaining to single-agent activities of the drug library (99 agents targeting 50 classes of proteins) suggested that the active concentrations ranged from ~10 nM to ~10 μM. For the combination experiments, cells were treated with the compounds at three concentrations covering a 100-fold concentration range (10-fold dilution), with or without a fixed dose of OP or NP (~20% IR). In HCC1937 cells, 3.5 μM OP or 3.5 μM NP; in HCT-15 cells, 20 μM OP or 2.5 μM NP. A drug response score, indicating the effect of PARPi combined with the indicated agent, was calculated as ΔIR. For each screened drug dose, a ΔIR was calculated: ΔIR = inhibition rate of (combination IR3–indicated agent IR1–PARPi IR2), the closed and open left angle triangle represent two different inhibitors from the same drug target, and their concentration decreases from left to right. B and C Effect of single agent and combination treatment on HCC1937 and HCT-15 cells viability for combinations of PARP inhibitor (olaparib, OP), plus CDK1 inhibitor (CDK1i) RO-3306 (B) or ATR inhibitor (ATRi) VE-821 (C). Cell viability was measured by Sulforhodamine B (SRB) assay. Combination index (CI) was calculated using CompuSyn software with the Chou–Talalay equation, and average CI values are presented (CI < 1, synergism; CI = 1, additive effect; CI > 1 antagonism). Data are from three independent experiments and expressed as mean ± standard deviation (SD).