Cystic fibrosis transmembrane conductance regulator modulates neurosecretory function in pulmonary neuroendocrine cell-related tumor cell line models.
The pulmonary neuroendocrine cell (PNEC) system consists of solitary cells and distinctive cell clusters termed neuroepithelial bodies (NEB) localized in the airway epithelium. PNEC/NEB express a variety of bioactive substances, including amine (serotonin, 5HT) and neuropeptides. We have previously shown that NEB cells are O(2) sensors expressing nicotinamide adenine diphosphate oxidase complex and O(2) sensitive K(+) channel. Recently, we demonstrated expression of functional cystic fibrosis transmembrane conductance regulator (CFTR) and Cl(-) conductances in NEB cells of rabbit neonatal lung. Because PNEC/NEB are sparsely distributed and difficult to study in native lung, we investigated small-cell lung carcinoma (SCLC) and carcinoid tumor cell lines (tumor counterparts of normal PNEC/NEB) as models for PNEC/NEB. SCLC (H146, H345) and carcinoid (H727) cell lines express neuroendocrine cell markers, including chromogranin A, neural cell adhesion molecule (N-CAM), 5HT, and tryptophan hydroxylase. We report that H146, H345, and H727 express CFTR messenger RNA (reverse transcription polymerase chain reaction) and protein (immunoblotting) and possess functional CFTR Cl(-) conductance, demonstrated by an iodide efflux assay inhibitable by transfection with antisense CFTR. Using an immunoassay to quantitate 5HT secretion, we also show that downregulation of CFTR abolishes hypoxia-induced 5HT release, and reduces secretory response to high potassium. Our findings suggest that CFTR may modulate neurosecretory activity of PNEC/NEB possessing O(2) sensor function. We propose that these tumor cell lines may be useful models for investigating the role of CFTR in PNEC/NEB functions in health and disease.
Pan
Jie
J
Department of Paediatric Laboratory Medicine and Programme in Structural Biology and Biochemistry, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada.
Bear
Christine
C
Farragher
Susan
S
Cutz
Ernest
E
Yeger
Herman
H
D015415:Biomarkers; D018288:Carcinoma, Small Cell / Q000378:metabolism; D015687:Cell Hypoxia; D053379:Chromogranin A; D002864:Chromogranins / Q000378:metabolism; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D008168:Lung / Q000166:cytology / Q000378:metabolism; D008175:Lung Neoplasms / Q000378:metabolism*; D019006:Neural Cell Adhesion Molecules / Q000378:metabolism; D009489:Neurosecretion / Q000502:physiology; D009490:Neurosecretory Systems / Q000166:cytology / Q000378:metabolism*; D012701:Serotonin / Q000235:genetics / Q000378:metabolism; D014365:Tryptophan Hydroxylase / Q000378:metabolism; D014407:Tumor Cells, Cultured
D015415:Biomarkers; C505032:CFTR protein, human; D053379:Chromogranin A; D002864:Chromogranins; D019006:Neural Cell Adhesion Molecules; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D012701:Serotonin; D014365:Tryptophan Hydroxylase