Figure 2

cAMP in PTH1R signaling and proliferation effects. a 8-CPT-cAMP attenuated the growth of H1944 cell number in a time- and dose-dependent fashion. Open diamonds, grey squares and black triangles represent cells left untreated or exposed to 100 and 200 µM 8-CPT-cAMP, respectively (n = 3 independent experiments, 6 replicates per experiment) *P < 0.05. b Increasing 8-CPT cAMP concentration caused progressively greater changes in cell number at day 5 with significant differences at 100 and 200 µM. *P < 0.05 and **P < 0.01 vs. untreated cells. c N-6-phenyl-cAMP (phe-cAMP), a cAMP analog targeting protein kinase A, and 8-CPT-2-O′-methyl-8-cAMP (me-cAMP), an EPAC-specific analog, both attenuated rate of increase in H1944 cell number over 5 days. Graph shows cell numbers at day 5. Concentrations range from 0 to 200 µM, as in panel b. **P < 0.01, ^§P < 0.001 vs. untreated cells. d phe-cAMP and me-cAMP retained their growth inhibitory effects regardless of PTH1R expression. The figure shows results for PTH1R-expressing NTC clones (PTH1R+) and PTH1R knockdown clones (PTH1R−). Cell number is expressed relative to untreated PTH1R-positive cells. ^§P < 0.001 vs. cells not treated with cAMP analog.