Characterization of intracellular calcium mobilization by bombesin-related neuropeptides in PC-3 human prostate cancer cells.

BACKGROUND

The objective of this study was to characterize the calcium mobilizing activity of bombesin-related neuropeptides in PC-3 cells.

METHODS

Intracellular free Ca2+ concentration ([Ca2+]i) was measured following the administration of bombesin-related neuropeptides using spectrofluorometric monitoring of PC-3 cells loaded with Fura2/AM.

RESULTS

Individual neuropeptides induced a rapid rise in [Ca2+]i immediately after stimulation in similar fashion. When two different peptides were administered simultaneously, the [Ca2+]i changes were similar to that produced by each peptide alone. However, simultaneous addition of tyr4-bombesin 100 nM and 2% serum resulted in [Ca2+]i increase greater than either alone. Sequential stimulation by same or different peptides, was not able to induce another response. However, 6 hrs after the first stimulus, a second stimulus was able to induce a similar response.

CONCLUSIONS

The data indicate that all members of the bombesin-related family of neuropeptides are capable of triggering calcium mobilization in PC-3 cells via a similar signalling pathway. PC-3 cells become acutely desensitized to additional stimulation of neuropeptide. This desensitization is selective and reversible, requiring approximately 6 hrs for recovery.