Xenobiotic-metabolizing enzyme activity in human non-small-cell derived lung cancer cell lines.
Human lung cancer cell lines in culture were investigated for the expression of monooxygenase and other xenobiotic-metabolizing enzyme activities. Two bronchiolo-alveolar carcinoma derived cell lines (NCI-H322 and NCI-H358) and two small-cell carcinoma derived cell lines (NCI-H128 and NCI-H69) were used. Previous work has shown that NCI-H322 has ultrastructural features of Clara cells while NCI-H358 shows characteristics of alveolar type II cells [Schuller et al., Proc. Am. Ass. Cancer Res. 26, 27 (1985)]. NCI-H128 and NCI-H69 show very poor differentiation of cytoplasmic organelles. Cytochrome P-450 levels were spectroscopically detectable only in NCI-H322. Both NCI-H322 and NCI-H358, but not NCI-H69 and NCI-H128, exhibited aryl hydrocarbon hydroxylase (using benzo[a] pyrene as substrate) and ethoxycoumarin O-deethylase activities. These activities were highly inducible following pretreatment with the polycyclic aromatic hydrocarbons (PAH) beta-naphthoflavone or benzo[a] anthracene. The PAH produced a 2-fold increase in spectroscopically detectable cytochrome P-450 levels in NCI-H322. Following induction, cytochrome P-450 was also spectroscopically detectable in NCI-H358. No aldrin epoxidase activity was present in either untreated or pretreated cell lines. Pretreatment with phenobarbitone or dexamethasone did not induce the aryl hydrocarbon hydroxylase activity in either NCI-H322 or NCI-H358. The ethoxycoumarin O-deethylase activity in beta-naphthoflavone-pretreated NCI-H322 and NCI-H358 was inhibited in a concentration-dependent manner by ellipticine, alpha-naphthoflavone, cimetidine or metyrapone. Untreated NCI-H322 and NCI-H358 also contained cytochrome b5, NADPH cytochrome c reductase and epoxide hydrolase activities. None of these enzyme activities measured was detectable in the untreated or pretreated small-cell derived cancer cell lines (NCI-H128 and NCI-H69). These data show that the two bronchiolo-alveolar carcinoma derived cell lines (NCI-H322 and NCI-H358) exhibit cytochrome P-448-dependent monooxygenase activity and may thus prove useful to study the processes of xenobiotic activation in human lung.
D015660:7-Alkoxycoumarin O-Dealkylase; D002282:Adenocarcinoma, Bronchiolo-Alveolar / Q000201:enzymology*; D001189:Aryl Hydrocarbon Hydroxylases / Q000378:metabolism; D018288:Carcinoma, Small Cell / Q000201:enzymology; D002460:Cell Line; D019388:Cytochrome P-450 CYP1A2; D003580:Cytochromes / Q000378:metabolism; D006801:Humans; D008175:Lung Neoplasms / Q000201:enzymology*; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D010105:Oxygenases / Q000037:antagonists & inhibitors / Q000378:metabolism; D013379:Substrate Specificity
D003580:Cytochromes; D006899:Mixed Function Oxygenases; D010105:Oxygenases; D015660:7-Alkoxycoumarin O-Dealkylase; D001189:Aryl Hydrocarbon Hydroxylases; C017170:Cyp1a2 protein, rat; D019388:Cytochrome P-450 CYP1A2