Epithelial neoplasia coincides with exacerbated injury and fibrotic response in the lungs of Gprc5a-knockout mice following silica exposure
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Xiaofei Wang1,2,*, Dongliang Xu3,4,*, Yueling Liao3,4,*, Shuangshuang Zhong3,4, Hongyong Song3,4, Beibei Sun5, Binhua P. Zhou6, Jiong Deng3,4,5, Baohui Han1,5
1Department of Pulmonary Medicine, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China
2Department of Pulmonary Medicine, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
3Key Laboratory of Cell Differentiation and Apoptosis of Chinese Minister of Education, Department of Pathophysiology, Shanghai, China
4Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, Shanghai, China
5Translation Medicine Center, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China
6Department of Molecular and Cellular Biochemistry, Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY, USA
*These authors have contributed equally to this work
Jiong Deng, e-mail: firstname.lastname@example.org
Baohui Han, e-mail: email@example.com
Keywords: SiO2, Gprc5a, fibrosis, lung cancer, neoplasia
Received: June 11, 2015 Accepted: September 21, 2015 Published: October 02, 2015
Exposure to crystalline silica is suggested to increase the risk for a variety of lung diseases, including fibrosis and lung cancer. However, epidemiological evidences for the exposure-risk relationship are ambiguous and conflicting, and experimental study from a reliable animal model to explore the relationship is lacking. We reasoned that a mouse model that is sensitive to both lung injury and tumorigenesis would be appropriate to evaluate the exposure-risk relationship. Previously, we showed that, Gprc5a−/− mice are susceptible to both lung tumorigenesis and endotoxin-induced acute lung injury. In this study, we investigated the biological consequences in Gprc5a−/− mouse model following silica exposure. Intra-tracheal administration of fine silica particles in Gprc5a−/− mice resulted in more severe lung injury and pulmonary inflammation than in wild-type mice. Moreover, an enhanced fibrogenic response, including EMT-like characteristics, was induced in the lungs of Gprc5a−/− mice compared to those from wild-type ones. Importantly, increased hyperplasia or neoplasia coincided with silica-induced tissue injury and fibrogenic response in lungs from Gprc5a−/− mice. Consistently, expression of MMP9, TGFβ1 and EGFR was significantly increased in lungs from silica-treated Gprc5a−/− mice compared to those untreated or wild-type ones. These results suggest that, the process of tissue repair coincides with tissue damages; whereas persistent tissue damages leads to abnormal repair or neoplasia. Thus, silica-induced pulmonary inflammation and injury contribute to increased neoplasia development in lungs from Gprc5a−/− mouse model.
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