Endothelin-1-induced potentiation of human airway smooth muscle proliferation: an ETA receptor-mediated phenomenon

R.A.JR. Panettieri, Roy Goldie, Paul Rigby, A.J. Eszterhas, D.W.P. Hay

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116 Citations (Scopus)

Abstract

1 In this study the mitogenic effects in human cultured tracheal smooth muscle cells of endothelin-l (ET-I), ET-3, and sarafotoxin S6c (S6c), the ET(B) receptor-selective agonist, were explored either alone or in combination with the potent mitogen, epidermal growth factor(EGF).2 In confluent, growth-arrested human airway smooth, neither ET-1 (0.01 nM - 1 mu M) nor ET-3 (0.001 nM - 1 mu M) Or S6c (0.01 nM - 1 mu M) induced cell proliferation, as assessed by [H-3]-thymidine incorporation. In contrast, EGF (1.6 pM - 16 nM) produced concentration-dependent stimulation of DNA synthesis (EC(50) of about 0.06 nM). The maximum increase of about 60 fold above control, elicited by 16 nM EGF, was similar to that obtained with 10% foetal bovine serum (FBS). EGF (0.16 - 16 nM) also produced a concentration-dependent increase in cell counts, whereas ET-1 (1 - 100 nM) was without effect on this index of mitogenesis.3 ET-1 (1 - 100 nM) potentiated EGF-induced proliferation of human tracheal smooth muscle cells. For example, ET-I (100 nM), which alone was without significant effect, increased by 3.0 to 3.5 fold the mitogenic influence of EGF (0.16 nM). The potentiating effect of ET-1 on EGF-induced proliferation was antagonized by BQ-123 (3 mu M), the ET(A) receptor antagonist, but was unaffected by the ET(B) receptor antagonist BQ-788 (10 mu M).4 Neither ET-3 (1 - 100 nM) nor S6c (1 - 100 nM) influenced the mitogenic effects of EGF (0.16 - 1.6 nM).5 [I-125]-ET-1 binding studies revealed that on average the ratio of ET(A) to ET(B) receptors in human cultured tracheal smooth muscle cells was 35:65 (+/- 3; n = 4), confirming the predominance of the ET(B) receptor subtype in human airway smooth muscle.6 These data indicate that ET-1 alone does not induce significant human airway smooth muscle cell proliferation. However, it potently potentiated mitogenesis induced by EGF, apparently via an ET(A) receptor-mediated mechanism. These findings suggest that ET-l, a mediator detected in increased amounts in patients with acute asthma, may potentiate the proliferative effects of mitogens and contribute to the airway smooth muscle hyperplasia associated with chronic severe asthma.
Original languageEnglish
Pages (from-to)191-197
JournalBritish Journal of Pharmacology
Volume118
DOIs
Publication statusPublished - 1996

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