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 2

FOXM1 is critical for fibroblast proliferation.

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FOXM1 is critical for fibroblast proliferation. (A) Time-dependent induc...
(A) Time-dependent induction of FOXM1 mRNA (analyzed by qPCR) in CCL210 cells by FGF2 stimulation in the presence and absence of actinomycin D. (B) Representative Western blot (from 1 of 3 independent experiments) of FOXM1 expression in CCL210 cells after 24 hours of treatment with and without FGF2. (C) qPCR analysis of FOXM1 mRNA expression in IPF and nonfibrotic fibroblasts treated for 48 hours with and without FGF2; cells from a given patient-derived line are denoted by a distinct numeral, and mean ± SEM relative values are depicted below the graphs. *P < 0.05; **P < 0.01 vs. no FGF2 control, 2-tailed paired t test. (D) Basal proliferation of fibroblasts from lungs of patients with IPF and control nonfibrotic lungs assayed by the CyQUANT NF Cell Proliferation Assay at 72 hours after culture. For C and D, values are expressed relative to those of normal fibroblasts. (E) Expression of cell cycle–regulated genes CCND1, CCNB1, PLK1, and BIRC5 determined by qPCR in CCL210 cells transfected with FOXM1 overexpression plasmid or control plasmid. (F and G) Effect of 24-hour pretreatment with FOXM1 or control (Cont) siRNA on FGF2-induced expression of FOXM1 (F) and cell cycle–regulated genes (G) as determined by qPCR. (H and I) Effect of treatment with 2.5 μM Sio A on FGF2-induced expression of FOXM1 (H) and cell cycle–regulated genes (I). (J) Effect of Sio A on basal and FGF2-induced cell proliferation, as determined by the CyQUANT NF Cell Proliferation Assay at 72 hours in culture. (K) Effect of Sio A and the known proteasome inhibitor MG132 on proteasome activity in lung fibroblasts, as determined by the 20S proteasome activity assay. For D and J, control value represents fluorescence value of cells initially seeded. *P < 0.05; **P < 0.01, 2-way ANOVA.