Effects Of All-trans Retinoic Rcid On The Proliferation Of Rat Vascular Smooth Muscle Cells And Expressions Of Cyclin A Protein And Cyclin-Dependent Kinase Inhibitor P16 Protein

Objective To study the effects of all-trans retinoic acid (ATRA) on proliferation of rat vascular smooth muscle cells (VSMCs), synthesis of DNA, expressions of CyclinA protein and Cyclin-Dependent Kinase Inhibitor(CKI) P16 protein, and to discuss the probable mechanisms of ATRA which regulate the proliferation of rat VSMCs.Methods Vascular smooth muscle cells from rat aorta were isolated sterily and cultured with explant method. VSMCs cultured in the serum-free media were free control group ( n=5 ), Fetal bovine serum and ATRA were added into the serum-free media at the concentrations of 20% and 2.5 n mol.L-1 together as experimentary group( n=5 ),and 20% fetal bovine alone as FBS group ( n=5 ) . VSMCs were harvested after 24h of stimulation.The proliferation of VSMCs and the synthesis of DNA were examined with 3H-TdR incorporation. The protein levels of cyclinA and CKI P16 were examined with western blotting and picture analysation.Results (1) Compared with free control group (VSMCs cultured 24h in the serum-free media), 20% FBS increased more 3H-TdR incorporation (11567. 09 ± 1974. 67vsl742. 68 + 615. 73, P<0. 001) and acercelerated proliferation and synthesis of DNA in VSMCs. 3H-TdR incorporation of experimentary group added with ATRA and 20% FBS simultaneously decreased obviously than that of FBS group (3725. 48 ± 643. 77vsll567. 09± 1974. 67, P<0. 01). ATRA inhibited significantly proliferation and synthesis of DNA in VSMCs. ?The protein level of cyclinA of FBS group was significantly higer than that of free control group (135. 92± 11. 95vsl 19. 31 ± 10. 10, P < 0.01)and that of experimentary group(135. 92±11. 95vsl22. 50±9. 59, P <0. 01). while the protein levels of CyclinA between free control group and experimentary group have no significant difference. (3)The protein level of PI 6 of FBS group was lower than that of free control group (72. 55 + 8. 95vs92. 14 + 10. 02, P<0. 05) and that of experimentary group (72. 55±8. 95vs100. 25±8. 54, P<0. 01) .while the protein levels of PI6 between free control group and experimentary group have no significant difference.Conclusions (1)ATRA can inhibited proliferation of VSMCs. (2)ATRA can downregulate protein CylinA and protein P16 of VSMCs(3) The possible mechanism of inhibition is associated with the downregulation of cyclinA protein and the upregulation of P16 protein.(4)ATRA may become one of effective medicine to deal with AS and stenosis after PTCA and stent surgery.