Effects of Rapamycin and mammalian target of rapamycin - small interfering RNA (mTOR siRNA)on proli-feration,apoptosis and extracellular matrix in premature rats lung fibroblasts exposed to hyperoxia / 中华实用儿科临床杂志

ABSTRACT

Objective To investigate the effects of Rapamycin and mammalian target of rapamycin - small in-terfering RNA (mTOR siRNA)on the proliferation,apoptosis and collagen Ⅰ(COLⅠ),collagen Ⅲ(COLⅢ)and fi-bronectin(FN)in premature rats lung fibroblasts exposed to hyperoxia. Methods 900 mL/ L volume fraction of oxygen was used to establish hyperoxia - damaged cell models,and the premature rats lung fibroblasts were divided into air control group,hyperoxia group,hyperoxia + rapamycin group and mammalian target of rapamycin - small interfering RNA transfection group. Cell proliferation was assessed by using 3 -(4,5 - Dimethylthiazol - 2 - yl)- 2,5 - dipheny-ltetrazolium bromide assay. Apoptosis were detected by Annexin V - FITC and propidium lodide (PI)double staining. The expressions of COLⅠ,COLⅢ and fibronectin was assessed by using enzyme linked immunosorbent assay and Bcl - 2,P53 and pro - fibrotic factors of connective tissue growth factor(CTGF)and transforming growth factor β(TGF - β)by using Western blot. Results Compared with the air control group,the proliferation of lung fibroblasts decreased and the apoptosis increased in the hyperoxia group,while the contents of COLⅠ(28. 30 ± 0. 53 vs. 17. 43 ±0. 37),COLⅢ(27. 86 ± 1. 02 vs. 17. 43 ± 0. 37)and fibronectin(32. 87 ± 0. 42 vs. 21. 57 ± 0. 47),P53(0. 810 ± 0. 119 vs. 0. 160 ± 0. 018),TGF - β(0. 580 ± 0. 108 vs. 0. 210 ± 0. 008)and CTGF(0. 590 ± 0. 017 vs. 0. 220 ± 0. 007)were also increased but the expression of Bcl - 2(0. 150 ± 0. 004 vs. 0. 600 ± 0. 130)protein was decreased, and the differences were all statistically significant (all P < 0. 01). Compared with the hyperoxia group,the proliferation of lung fibroblasts was increased in the hyperoxia + rapamycin group,but the apoptosis was decreased,the contents of COLⅠ(23. 17 ± 0. 60 vs. 28. 30 ± 0. 53),COLⅢ(17. 09 ± 0. 58 vs. 27. 86 ± 1. 02)and fibronectin(28. 11 ± 0. 68 vs. 32. 87 ± 0. 42),P53(0. 430 ± 0. 008 vs. 0. 810 ± 0. 119),TGF - β(0. 380 ± 0. 008 vs. 0. 580 ± 0. 108)and CTGF (0. 040 ± 0. 006 vs. 0. 590 ± 0. 017)were decreased while the expression of Bcl - 2(0. 290 ± 0. 009 vs. 0. 150 ± 0. 004) protein was increased,and the differences were all statistically significant (all P < 0. 01). In the mTOR siRNA transfec-tion group,compared with the hyperoxia + rapamycin group,the proliferation of lung fibroblasts was increased,but the apoptosis was decreased;the contents of COLⅠ(15. 71 ± 0. 34 vs. 23. 17 ± 0. 60),COLⅢ (13. 85 ± 1. 36 vs. 17. 09 ± 0. 58)and fibronectin(20. 18 ± 0. 28 vs. 28. 11 ± 0. 68),P53(0. 300 ± 0. 006 vs. 0. 430 ± 0. 008),TGF - β(0. 150 ± 0. 002 vs. 0. 380 ± 0. 008)and CTGF(0. 140 ± 0. 004 vs. 0. 040 ± 0. 006)were decreased while the expression of Bcl - 2 (0. 460 ± 0. 012 vs. 10. 290 ± 0. 009)protein was increased,and the differences were all statistically significant (all P < 0. 01). Conclusion Rapamycin and mTOR siRNA can protect lung injury caused by hyperoxia and have a certain inhibitory effect on pulmonary fibrosis,and mTOR siRNA effect is more obvious,so the mechanism may be through the inhibition of mTOR signaling pathway.