Expression of the α7 nicotinic acetylcholine receptor in human lung cells

Plummer, Dhar Madhu, Schuller

Description

We and others have shown that one of the mechanisms of growth regulation of small cell lung cancer cell lines and cultured pulmonary neuroendocrine cells is by the binding of agonists to the α7 neuronal nicotinic acetylcholine receptor. In addition, we have shown that the nicotine-derived carcinogenic nitrosamine, 4(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), is a high affinity agonist for the α7 nicotinic acetylcholine receptor. In the present study, our goal was to determine the extent of α7 mRNA and protein expression in the human lung. Methods Experiments were done using reverse transcription polymerase chain reaction (RT-PCR), a nuclease protection assay and western blotting using membrane proteins. Results We detected mRNA for the neuronal nicotinic acetylcholine receptor α7 receptor in seven small cell lung cancer (SCLC) cell lines, in two pulmonary adenocarcinoma cell lines, in cultured normal human small airway epithelial cells (SAEC), one carcinoid cell line, three squamous cell lines and tissue samples from nine patients with various types of lung cancer. A nuclease protection assay showed prominent levels of α7 in the NCI-H82 SCLC cell line while α7 was not detected in SAEC, suggesting that α7 mRNA levels may be higher in SCLC compared to normal cells. Using a specific antibody to the α7 nicotinic receptor, protein expression of α7 was determined. All SCLC cell lines except NCI-H187 expressed protein for the α7 receptor. In the non-SCLC cells and normal cells that express the α7 nAChR mRNA, only in SAEC, A549 and NCI-H226 was expression of the α7 nicotinic receptor protein shown. When NCI-H69 SCLC cell line was exposed to 100 pm NNK, protein expression of the α7 receptor was increased at 60 and 150 min. Conclusion Expression of mRNA for the neuronal nicotinic acetylcholine receptor α7 seems to be ubiquitously expressed in all human lung cancer cell lines tested (except for NCI-H441) as well as normal lung cells. The α7 nicotinic receptor protein is expressed in fewer cell lines, and the tobacco carcinogen NNK increases α7 nicotinic receptor protein levels.

Informations

• Publié par: biomed
• Publié le: 01 janvier 2005
• Nombre de lectures: 2
• Langue: English
• Poids de l'ouvrage: 1 Mo

Extrait

Respiratory Research

BioMedCentral

Open Access Research Expression of the
7 nicotinic acetylcholine receptor in human lung cells 1 1 2 Howard K Plummer III* , Madhu Dhar and Hildegard M Schuller

1 Address: Molecular Cancer Analysis Laboratory, Department of Pathobiology, College of Veterinary Medicine, University of Tennessee, Knoxville, 2 TN 379964542, USA and Experimental Oncology Laboratory, Department of Pathobiology, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 379964542, USA Email: Howard K Plummer*  [e-mail]; Madhu Dhar  [e-mail]; Hildegard M Schuller  [e-mail] * Corresponding author

Published: 04 April 2005 Received: 06 January 2005 Accepted: 04 April 2005 Respiratory Research2005,6:29 doi:10.1186/1465-9921-6-29 This article is available from: http://respiratory-research.com/content/6/1/29 © 2005 Plummer et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract Background:We and others have shown that one of the mechanisms of growth regulation of small cell lung cancer cell lines and cultured pulmonary neuroendocrine cells is by the binding of agonists to the
7 neuronal nicotinic acetylcholine receptor. In addition, we have shown that the nicotine-derived carcinogenic nitrosamine, 4(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), is a high affinity agonist for the
7 nicotinic acetylcholine receptor. In the present study, our goal was to determine the extent of
7 mRNA and protein expression in the human lung. Methods:Experiments were done using reverse transcription polymerase chain reaction (RT- PCR), a nuclease protection assay and western blotting using membrane proteins. Results:We detected mRNA for the neuronal nicotinic acetylcholine receptor
7 receptor in seven small cell lung cancer (SCLC) cell lines, in two pulmonary adenocarcinoma cell lines, in cultured normal human small airway epithelial cells (SAEC), one carcinoid cell line, three squamous cell lines and tissue samples from nine patients with various types of lung cancer. A nuclease protection assay showed prominent levels of
7 in the NCI-H82 SCLC cell line while
7 was not detected in SAEC, suggesting that
7 mRNA levels may be higher in SCLC compared to normal cells. Using a specific antibody to the
7 nicotinic receptor, protein expression of
7 was determined. All SCLC cell lines except NCI-H187 expressed protein for the
7 receptor. In the non-SCLC cells and normal cells that express the
7 nAChR mRNA, only in SAEC, A549 and NCI- H226 was expression of the
7 nicotinic receptor protein shown. When NCI-H69 SCLC cell line was exposed to 100 pm NNK, protein expression of the
7 receptor was increased at 60 and 150 min.

Conclusion:Expression of mRNA for the neuronal nicotinic acetylcholine receptor
7 seems to be ubiquitously expressed in all human lung cancer cell lines tested (except for NCI-H441) as well as normal lung cells. The
7 nicotinic receptor protein is expressed in fewer cell lines, and the tobacco carcinogen NNK increases
7 nicotinic receptor protein levels.

Background We and others have shown that one of the mechanisms of

growth regulation of small cell lung cancer (SCLC) cell lines and cultured pulmonary neuroendocrine cells

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