Fibroblast-specific inhibition of TGF-β1 signaling attenuates lung and tumor fibrosis

• DOI: 10.1172/jci94624
• Publication Date: 2017-09-04T22:00:30Z
• Authors: Ying Wei; Thomas J. Kim; David H. Peng; Dana Duan; Don L. Gibbons; Mitsuo Yamauchi; Julia R. Jackson; Claude J. Le Saux; Cheresa Calhoun; Jay Peters; Rik Derynck; Bradley J. Backes; Harold A. Chapman
• Keywords: 0301 basic medicine; Biomedical and clinical sciences; Epithelial-Mesenchymal Transition; Lung Neoplasms; Pulmonary Fibrosis; Immunology; Receptor, Transforming Growth Factor-beta Type I; 610; Protein Serine-Threonine Kinases; Drug Screening Assays; Medical and Health Sciences; Transforming Growth Factor beta1; Mice; 03 medical and health sciences; Phenols; Transforming Growth Factor beta; Receptors; 2.1 Biological and endogenous factors; Animals; Humans; Aetiology; Enzyme Inhibitors; Neoplasm Metastasis; Lung; Protein Kinase Inhibitors; Cancer; Biomedical and Clinical Sciences; Lung Cancer; 500; Health sciences; Antitumor; Biological Sciences; Fibroblasts; Neoplasm Proteins; 3. Good health; Biological sciences; Transforming Growth Factor-beta Type I; 5.1 Pharmaceuticals; A549 Cells; Biochemistry and Cell Biology; Amino Acid Oxidoreductases; Development of treatments and therapeutic interventions; Drug Screening Assays, Antitumor; Receptors, Transforming Growth Factor beta; Receptor; Signal Transduction

TGF-β1 signaling is a critical driver of collagen accumulation and fibrotic disease but also a vital suppressor of inflammation and epithelial cell proliferation. The nature of this multifunctional cytokine has limited the development of global TGF-β1 signaling inhibitors as therapeutic agents. We conducted phenotypic screens for small molecules that inhibit TGF-β1–induced epithelial-mesenchymal transition without immediate TGF-β1 receptor (TβR) kinase inhibition. We identified trihydroxyphenolic compounds as potent blockers of TGF-β1 responses (IC50 ~50 nM), Snail1 expression, and collagen deposition in vivo in models of pulmonary fibrosis and collagen-dependent lung cancer metastasis. Remarkably, the functional effects of trihydroxyphenolics required the presence of active lysyl oxidase–like 2 (LOXL2), thereby limiting effects to fibroblasts or cancer cells, the major LOXL2 producers. Mechanistic studies revealed that trihydroxyphenolics induce auto-oxidation of a LOXL2/3–specific lysine (K731) in a time-dependent reaction that irreversibly inhibits LOXL2 and converts the trihydrophenolic to a previously undescribed metabolite that directly inhibits TβRI kinase. Combined inhibition of LOXL2 and TβRI activities by trihydrophenolics resulted in potent blockade of pathological collagen accumulation in vivo without the toxicities associated with global inhibitors. These findings elucidate a therapeutic approach to attenuate fibrosis and the disease-promoting effects of tissue stiffness by specifically targeting TβRI kinase in LOXL2-expressing cells.