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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This work was supported by grants from, Ministry of Science and Technology No. 2013CB910901 (J.Deng), National Nature Science Foundation of China 91129303 (J.Deng), 81071923 (J.Deng), Science and Technology Commission of Shanghai (10140902100) (J.Deng), and China Postdoctoral Science Foundation Grant (2014M551421) (H. Song).
Wang, Xiaofei; Xu, Dongliang; Liao, Yueling; Zhong, Shuangshuang; Song, Hongyong; Sun, Beibei; Zhou, Binhua P.; Deng, Jiong; and Han, Baohui, "Epithelial Neoplasia Coincides with Exacerbated Injury and Fibrotic Response in the Lungs of Gprc5a-Knockout Mice Following Silica Exposure" (2015). Markey Cancer Center Faculty Publications. 57.