Identification of functional somatostatin receptors and G-proteins in a new line of human foetal lung fibroblasts

A new line (FP) of human foetal lung fibroblasts was analysed for the expre ssion of functional, G-protein coupled somatostatin receptors (SSTR). By me ans of RT-PCR, we identified the expression of SSTR1, SSTR2, SSTR3 and SSTR 4, but not SSTR5, subtypes. The same technical approach evidenced the expre ssion of stimulatory (alpha(s)) and inhibitory (alpha(i1), alpha(i2) and al pha(i3)) G-protein subunits. The functionality of SSTR was established from the observation of a dose-dependent inhibitory role of SST upon isoprotere nol-stimulated adenylyl cyclase activity, an effect that involves G-protein action. Moreover, the functionality of G-proteins was assessed by means of experiments with forskolin and a nonhydrolysable GTP analogue that showed either Gi or Gs activation in the regulation of adenylyl cyclase. Present r esults represent a first pharmacological characterization of this new line of human foetal lung fibroblasts. The selective presence of some SSTR subty pes and G-protein subunits in addition to the regulatory network of the ade nylyl cyclase pathway are features of recognized involvement in cell growth mechanisms. It is of interest for a cell class widely used to study this t opic but also important in lung physiology and pathophysiology.