Objective To study the expression and significance of aquaporin-1 (AQP-1) in human alveolar epithelial line A549 cells stimulated by silica.
Methods A549 cells were divided into control, silica-stimulated, and inhibitor groups. The cells of the silica-stimulated group and the inhibitor group were stimulated by 50 mg/L silicon dioxide dispersed suspension to detect their mRNA expressions after 0.5, 1, 2, 4, and 8 h and protein expressions after 3, 6, 12, and 24 h. The cells of the inhibitor group were pretreated with mercuric chloride (specific channel inhibitor of AQP-1) for 3 minutes and then stimulated by silicon dioxide for 2 h to detect mRNA expression or for 6 h to detect protein expression. The expression of AQP-1 protein was detected by Western blot and immunocytochemistry and the expression of AQP-1 mRNA of the cells was detected by real-time polymerase chain reaction.
Results Compared with the control group, the expression level of AQP-1 mRNA in silica-stimulated cells was 2.78, 3.52, 3.85, and 1.98 times after 0.5, 1, 2, and 4 h of silica-stimulation respectively (P<0.01), and returned to the control level after 8 h; the expression level of the inhibitor group was 65% of the corresponding silica-stimulated group. According to Western blot assay, the expression level of AQP-1 protein of the silica-stimulated cells was 1.44, 2.56, 1.93, and 1.35 times of the control group after 3, 6, 12, and 24 h of silica-stimulation respectively (P<0.05 or P<0.01); the level of the inhibitor group was 70% of the corresponding silica-stimulated group (P<0.01). According to immunocytochemistry, the expression level of AQP-1 protein was 1.17, 1.49, 1.29, and 1.07 times of the control group after silica administration for 3, 6, 12, and 24 h respectively (P<0.05 or P<0.01); that of the inhibitor group was 71% of the corresponding silica-stimulated group (P<0.01).
Conclusion Elevated expression levels of AQP-1 mRNA and protein are induced by silica, and the specific inhibitor mercuric chloride could inhibit the increased expression, suggesting that AQP-1 participates the development of silicosis.
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