Peptide amidating activity in human bronchoalveolar lavage fluid: Relationship to lung cancer, inflammation and infection

The most common post-translational modification of peptide hormones, presen t in half of all neuroendocrine (NE) peptides, is alpha-amidation and this is necessary for the biological activity of the peptides. Peptides are alph a-amidated by the action of two enzymes: peptidylglycine alpha-hydroxylatin g monooxygenase (PHM) and peptidylamidoglycolate lyase (PAL). As the common pathway for the formation of amidated peptides, the enzymes may provide a better indication of the NE status of a tumour or tissue than the presence of any single amidated peptide. PHM and PAL enzyme activities were measured in 39 BL-fluid specimens from patients undergoing bronchoscopy for diagnos is of lung cancer. The assays revealed that PHM levels were higher in a gro up of specimens from patients undergoing bronchoscopy for chest infection, inflammation, asthma, or pneumonia compared to a group of specimens in whic h malignant cells were seen. The presence of elevated levels of amidating e nzymes in specimens with non-cancerous conditions may reflect events of pro motional phase cancer biology occurring simultaneously with inflammatory an d infectious processes.