[Impact of sirolimus on collagen synthesis in vascular smooth muscle cells: experiment with rat].
OBJECTIVE
To evaluate effects of sirolimus on collagen synthesis and collagen type I and type III mRNA expression in vascular smooth muscle cells (VSMCs).


METHODS
Rat VSMCs from thoracic aorta were cultured and added with sirolimus of the concentrations of 0, 0.1, 1.0, 10, and 100 ng/ml respectively for 24 h, then co-cultured with L-(3)H-proline for 12 h. L-(3)H-proline incorporation was monitored by liquid scintillation counting. RT-PCR was used to detect the mRNA expression of collagen type I and collagen type III. Logarithmic phase VSMC were treated with sirolimus by 0 ng/ml, 0.1 ng/ml, 1 ng/ml, 10 ng/ml and 100 ng/ml respectively for 24 h prior to 12 h exposure to L-(3)H-proline.


RESULTS
The proline incorporation values were 1369 +/- 186, 1211 +/- 157, 1037 +/- 139, 910 +/- 144, and 741 +/- 160 cpm respectively of the 0, 0.1, 1, 10, and 100 ng/ml sirolimus groups. Paired t-test analysis showed that the proline incorporation value of the group with higher sirolimus concentration was significantly lower than that of the group with lower sirolimus concentration (F = 18.936, P < 0.001), except between the 0.1 ng/ml group and 0 ng/ml group (control group) and between the 1 ng/ml group and 10 ng/ml group (P = 0.057, P = 0.12). RT-PCR showed that the collagen I levels were 112 +/- 23, 140 +/- 23, 152 +/- 12, 166 +/- 22, and 179 +/- 18 respectively in the groups of sirolimus of the concentrations of 100, 10, 1, 0.1, and 0 ng/ml respectively, the higher the concentration of sirolimus the lower the collagen I level (all P < 0.05), however, there was no significant difference in the collagen I level between the 0.1 mg/ml group and the control group (P = 0.236). There was no significant difference in the collagen III level among the groups of sirolimus of different concentrations (F = 2.409, P = 0.070).


CONCLUSIONS
Sirolimus inhibits the collagen synthesis in the VSMCs and attenuates the mRNA expression of type I collagen concentration-dependently.
Li
Jia-Ping
JP
Department of Interventional Radiology, First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510080, China.
Yang
Jian-Yong
JY
Chen
Wei
W
Zhuang
Wen-Quan
WQ
Wang
Jian-Bo
JB
D000818:Animals; D002478:Cells, Cultured; D024042:Collagen Type I / Q000096:biosynthesis / Q000235:genetics*; D024061:Collagen Type III / Q000096:biosynthesis / Q000235:genetics*; D004305:Dose-Response Relationship, Drug; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020123:Sirolimus / Q000494:pharmacology*
D024042:Collagen Type I; D024061:Collagen Type III; D012333:RNA, Messenger; D020123:Sirolimus