title: Down-regulation of dihydrofolate reductase inhibits the growth of endothelial EA.hy926 cell through induction of G1 cell cycle arrest via up-regulating p53 and p21(waf1/cip1) expression.
abstract: Folic acid supplementation may meliorate cardiovascular disease risk by improving vascular endothelial structure and function. However, the underlying mechanisms are still lack of a global understanding. To be used, folic acid must be converted to 7,8-dihydrofolate by dihydrofolate reductase to generate one-carbon derivatives serving as important cellular cofactors in the synthesis of nucleotides and amino acids required for cell growth. Therefore, this study explored the effect of dihydrofolate reductase knockdown on endothelial EA.hy926 cell growth and the mechanism involved. We found that down-regulation of dihydrofolate reductase inhibited EA.hy926 cell proliferation, and induced G1 phase arrest. Meanwhile, the expression of regulators necessary for G1/S phase transition, such as cyclin-dependent kinases CDK2, CDK4 and CDK6, were remarkably down-regulated; by contrast, the cell cycle inhibitors p21(waf/cip1), p27(Kip1) and p53 were significantly up-regulated after dihydrofolate reductase knockdown. Furthermore, supplementation of 5-methyltetrahydrofolate to the dihydrofolate reductase knockdown cells could weaken the inhibitory effect of dihydrofolate reductase knockdown on cell proliferation, simultaneously, inducing the expression of p53 and p21(waf/cip1) falling back moderately. Our findings suggest that attenuating dihydrofolate reductase may cause imbalanced expression of cell cycle regulators, especially up-regulation of p53-p21(waf/cip1) pathway, leading to G1 cell cycle arrest, thereby inhibiting the growth of endothelial EA.hy926 cells.
authors.affiliation: Department of General Surgery, Xinhua Hospital (Chong Ming) affiliated to Shanghai Jiaotong University School of Medicine, Shanghai 202150, China.
authors.forename: Zhewei
authors.initials: Z
authors.lastname: Fei
authors.affiliation: Department of Vascular Surgery, The First Affiliated Hospital of Bengbu Medical College, An Hui Province 233003, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Department of General Surgery, Xinhua Hospital affiliated to Shanghai Jiaotong University School of Medicine, Shanghai 200092, China.
authors.forename: Mingke
authors.initials: M
authors.lastname: Qiu
authors.affiliation: Department of General Surgery, Xinhua Hospital affiliated to Shanghai Jiaotong University School of Medicine, Shanghai 200092, China.
authors.forename: Xianqin
authors.initials: X
authors.lastname: Qi
authors.affiliation: Department of General Surgery, Xinhua Hospital affiliated to Shanghai Jiaotong University School of Medicine, Shanghai 200092, China.
authors.forename: Yuxin
authors.initials: Y
authors.lastname: Dai
authors.affiliation: Department of General Surgery, Xinhua Hospital affiliated to Shanghai Jiaotong University School of Medicine, Shanghai 200092, China.
authors.forename: Shuqing
authors.initials: S
authors.lastname: Wang
authors.affiliation: Department of General Surgery, Xinhua Hospital affiliated to Shanghai Jiaotong University School of Medicine, Shanghai 200092, China.
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Quan
authors.affiliation: Department of General Surgery, Xinhua Hospital affiliated to Shanghai Jiaotong University School of Medicine, Shanghai 200092, China.
authors.forename: Yingbin
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of General Surgery, Xinhua Hospital affiliated to Shanghai Jiaotong University School of Medicine, Shanghai 200092, China.
authors.forename: Jingmin
authors.initials: J
authors.lastname: Ou
keywords: G1 cell cycle; dihydrofolate reductase; endothelial cell; p21waf/cip1; p53