| First Author | Le K | Year | 2018 |
| Journal | Proc Natl Acad Sci U S A | Volume | 115 |
| Issue | 5 | Pages | E944-E953 |
| PubMed ID | 29339522 | Mgi Jnum | J:257758 |
| Mgi Id | MGI:6115404 | Doi | 10.1073/pnas.1719960115 |
| Citation | Le K, et al. (2018) Effect of beta-agonists on LAM progression and treatment. Proc Natl Acad Sci U S A 115(5):E944-E953 |
| abstractText | Lymphangioleiomyomatosis (LAM), a rare disease of women, is associated with cystic lung destruction resulting from the proliferation of abnormal smooth muscle-like LAM cells with mutations in the tuberous sclerosis complex (TSC) genes TSC1 and/or TSC2 The mutant genes and encoded proteins are responsible for activation of the mechanistic target of rapamycin (mTOR), which is inhibited by sirolimus (rapamycin), a drug used to treat LAM. Patients who have LAM may also be treated with bronchodilators for asthma-like symptoms due to LAM. We observed stabilization of forced expiratory volume in 1 s over time in patients receiving sirolimus and long-acting beta-agonists with short-acting rescue inhalers compared with patients receiving only sirolimus. Because beta-agonists increase cAMP and PKA activity, we investigated effects of PKA activation on the mTOR pathway. Human skin TSC2(+/-) fibroblasts or LAM lung cells incubated short-term with isoproterenol (beta-agonist) showed a sirolimus-independent increase in phosphorylation of S6, a downstream effector of the mTOR pathway, and increased cell growth. Cells incubated long-term with isoproterenol, which may lead to beta-adrenergic receptor desensitization, did not show increased S6 phosphorylation. Inhibition of PKA blocked the isoproterenol effect on S6 phosphorylation. Thus, activation of PKA by beta-agonists increased phospho-S6 independent of mTOR, an effect abrogated by beta-agonist-driven receptor desensitization. In agreement, retrospective clinical data from patients with LAM suggested that a combination of bronchodilators in conjunction with sirolimus may be preferable to sirolimus alone for stabilization of pulmonary function. |
