FOXM1 is a critical driver of lung fibroblast activation and fibrogenesis
Loka R. Penke, Jennifer M. Speth, Vijaya L. Dommeti, Eric S. White, Ingrid L. Bergin, Marc Peters-Golden
Loka R. Penke, Jennifer M. Speth, Vijaya L. Dommeti, Eric S. White, Ingrid L. Bergin, Marc Peters-Golden
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Research Article Pulmonology

FOXM1 is a critical driver of lung fibroblast activation and fibrogenesis

Abstract

While the transcription factor forkhead box M1 (FOXM1) is well known as a proto-oncogene, its potential role in lung fibroblast activation has never been explored. Here, we show that FOXM1 is more highly expressed in fibrotic than in normal lung fibroblasts in humans and mice. FOXM1 was required not only for cell proliferation in response to mitogens, but also for myofibroblast differentiation and apoptosis resistance elicited by TGF-β. The lipid mediator PGE2, acting via cAMP signaling, was identified as an endogenous negative regulator of FOXM1. Finally, genetic deletion of FOXM1 in fibroblasts or administration of the FOXM1 inhibitor Siomycin A in a therapeutic protocol attenuated bleomycin-induced pulmonary fibrosis. Our results identify FOXM1 as a driver of lung fibroblast activation and underscore the therapeutic potential of targeting FOXM1 for pulmonary fibrosis.

Authors

Loka R. Penke, Jennifer M. Speth, Vijaya L. Dommeti, Eric S. White, Ingrid L. Bergin, Marc Peters-Golden

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Figure 6

FOXM1 inhibition prevents and reverses TGF-β–induced myofibroblast differentiation and sensitizes myofibroblasts to FasL-induced apoptosis.

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FOXM1 inhibition prevents and reverses TGF-β–induced myofibroblast diffe...
(A–C) Effects of a 1-hour pretreatment of CCL210 cells with 2.5 μM Sio A (prevention protocol) on TGF-β–induced expression of α-SMA mRNA (A) and protein (B, Western blot; C, immunofluorescence microscopy) as well as collagen I protein (B). (D) Basal levels of ACTA2 mRNA in lung fibroblasts isolated from IPF patients or nonfibrotic controls (n = 5). (E) Effect of transfection with FOXM1 siRNA or scrambled (control) siRNA (for 16 hours) (left) or 30-minute pretreatment with 2.5 μM Sio A (right) on ACTA2 mRNA levels in IPF or control lung fibroblasts (n = 5) stimulated with and without TGF-β for 24 hours. (F) Immunofluorescence microscopic analysis of α-SMA expression in TGF-β–generated myofibroblasts treated with 2.5 μM Sio A for 24 hours (reversal protocol). (G) Effect of transfection with FOXM1 siRNA or scrambled (control) siRNA (for 16 hours) on FasL-induced apoptosis and expression of apoptosis-associated genes FAS, CASP3, and BIRC5 by Western blot analysis of TGF-β–generated myofibroblasts. (H and I) Effects of a 1-hour pretreatment with 2.5 μM Sio A on FasL-induced apoptosis in TGF-β–generated myofibroblasts, as determined by cleaved PARP expression assessed by Western blot (H) and by the frequency of annexin V staining assessed by flow cytometric analysis (I). (J) Effect of Sio A treatment for 24 hours on BIRC5 expression in nonfibrotic control and IPF fibroblasts. *P < 0.05, 2-way ANOVA. Images in C and D are representative immunofluorescence images showing α-SMA (green) and DAPI (blue). Original magnification, ×200. Western blots in B, G, and H are representative of 3 independent experiments. *P < 0.05, 2-way ANOVA.