Fig. 1.

The ability of GRP, NMB, [DTyr⁶, βAla¹¹,Phe¹³,Nle¹⁴]Bn(6-14) (Peptide # 1) and various putative BRS-3 selective agonists including peptide #16a, to inhibit binding and to stimulate an increase in [³H]IP formation in N417 lung cancer cells natively expressing hBRS-3 or in H1299 lung cancer cells over-expressing hBRS-3. For binding (top panel) N417 cells (1.5 × 10⁶ cell/ml or hBRS-3/H1299 cells (0.5 × 10⁶ cells/ml) cells were incubated for 60 min at at 22°C with 50 pM I¹²⁵- [DTyr⁶, βAla¹¹,Phe¹³, Nle¹⁴]Bn(6-14), with or without the indicated concentrations of the various peptides added. Results are expressed as the percentage of saturable binding without unlabeled peptide added (percent control). Bottom panel, N417 cells or hBRS-3/H1299 cells were subcultured and preincubated for 24 h at 37°C with 3 uCi/ml myo-[2-³H]inositol. The cells were then incubated with the ligands at the concentrations indicated for 60 min at 37°C. Values expressed are a percentage of total [³H]IP release stimulated by 1 μM [DTyr⁶, βAla¹¹,Phe¹³,Nle¹⁴]Bn(6-14). Control and 1 μM [DTyr⁶, βAla¹¹, Phe¹³,Nle¹⁴]Bn(6-14)-stimulated values for N417 lung cancer cells were 1362 ± 230 and 4952 ± 405 dpm, respectively and for H1299/BRS-3 cells were 1988 ± 220 and 10891 ± 540 dpm, respectively. Results are the mean ± SEM from at least four experiments, and in each experiment the data points were determined in duplicate. Numbers refer to the peptide number in Table 1. Abbreviations: See Table 1 legend.