Fig. 7
Lung squamous cell carcinoma and adenocarcinoma cells display increasing sensitivity to compounds 1, 3–5 in terms of proliferation, dependent upon combined A2AR and PDE10A expression. Lung squamous cell carcinoma cells (LK-2 and H520) and lung adenocarcinoma cells (H1792 and H1563 were subjected to semi-quantitative RT-PCR analysis to determine expression of the A1R, A2AR, A2BR, A3R and PDE 10A, data represented relative to GAPDH expression, ± SEM of 3 individual replicates. Further, each cell line was stimulated with CGS21680 or compounds 1, 3–6 for 30 minutes and cAMP levels determined. Data represented relative to the response obtained upon stimulation with 100 µM Forskolin, ± SEM of 4–8 individual replicates. Additionally, all cells were stimulated with CGS21680, or 1, 3–6 for 72 hours and cell number determined using CCK-8. Data represented as a percentage of the cell number present after treatment with 1 % DMSO, ± SEM of 4–8 replicates. (B) Correlation plot for pEC50 of each compounds ability to stimulate cAMP production vs. its pIC50 for inhibiting proliferation. Data represented ± SEM. (C) Proliferation factor (pIC50 x span anti-proliferative Additional file 1: Table S5) calculated for 1, 3–6, CGS21680s and forskolin at LK-2, H520, H1792 and H1563 cells. Bars represent the mean Imax ± SEM, whilst individual data points are shown as a scatter plot.