The biochemistry of epithelia: enzyme levels in bronchial and tracheal epithelia of smokers and non-smokers and in bronchial carcinoma

Abstract

Epithelia from the bronchus and trachea of human males over the age of 40 were removed within 6 hr. post mortem and stored at -20[degree] as suspensions in 0-25 M-sucrose containing 0.01 M-ethylenediaminetetraacetate, pH 7.4. Clinical histories and smoking habits of the subjects were noted. The acid phosphatase, [beta]-glucuronidase, arylsulphatases A plus B, aryl-sulphatase C, and lactic and malic dehydrogenase activities of these suspensions were assayed and correlated with total and differential cell counts, protein nitrogen and deoxyribonucleic acid and ribonucleic acid contents. The activities of all the enzymes showed good correlation with the ribonucleic acid content of the epithelial cells, the regression lines having correlation coefficients of between 0.54 and 0.94. There was no significant correlation between enzyme activities and any of the other parameters. The enzyme activities of suspensions of surgically removed bronchial carcinomas (5 specimens) and human bronchial carcinoma transplants in hamster cheek-pouch (2 specimens) fitted reasonably well onthe regression lines. Analysis of these results suggested that all the enzymes examined are of cytoplasmic occurrence, that they are not directly involved in cilia action or mucus production and that they are not specifically involved in the differentiation of the basal epithelial cells into columnar, squamour or neoplastic cells.