Activation of large form galanin-LI by extracellular processing in small cell lung carcinoma tissue

Galanin is a neuropeptide that is widely distributed in the central and peripheral nervous systems. some small cell lung carcinoma (sclc) cell lines such as sbc-3a release only the high-molecular-mass form,with lower molecular mass forms being undetectable. to investigate the mechanism of processing of progalanin to active peptide,we studied galanin-li in both the culture media of sbc-3a cells and in extracts from in vivo mouse sbc-3a tumors. sbc-3a cells were found to release high molecular mass galanin,but did not release active peptides. in contrast,tumor extract contained both high-molecular-mass galanin,and a cleaved lower-molecular-mass form of the peptide (8,5 and 2 kda). the lower-molecular-mass peptide was identified as galanin(1-20) by maldi-tof mass spectrometry. we then looked at mmp-2 and mmp-9 release from sbc-3a cells and tumor tissue treated with galanin and progalanin,as revealed by gelatin zymography. galanin elicited pro-mmp-2 and pro-mmp-9 release from sbc-3a cells and tumor tissue; however,recombinant progalanin induced pro-mmp-2 and pro-mmp-9 release from tumor tissue only. this study has shown that the galanin-li released from sclc sbc-3a cells consisted of the high-molecular-mass peptide form,and was processed extracellularly to galanin(1-20). furthermore,galanin was seen to induce pro-mmp-2 and pro-mmp-9 release from sbc-3a cells. © 2011 bentham science publishers.