Folic acid inhibits endothelial cell proliferation through activating the cSrc/ERK 2/NF-κB/p53 pathway mediated by folic acid receptor

Abstract

Folate is important for normal cell division. Folate deficiency has been implicated in various diseases, including atherosclerosis, neural tube defects, and cancer. However, the effect of folate on angiogenesis was unclear. The aim of this study was to investigate the anti-angiogenic action of folic acid (FA). FA (0-10 μmol/L) concentration-dependently decreased DNA synthesis and proliferation in cultured human umbilical venous endothelial cells (HUVEC). Western blot analyses demonstrated that the levels of p21, p27 and p53 protein in HUVEC were increased by FA. The FA-inhibited [3H]thymidine incorporation was completely blocked when the expressions of p21 and p27 were knocked-down together. Knock-down of p53 prevented the FA-induced increases in p21 and p27 protein level. The levels of phosphorylated Src (p-Src) and p-Src-FA receptor (FR) complex in HUVEC were increased by FA. Knock-down of FR reduced the FA-induced increases of p-Src and p53. The FA-induced increases of p21, p27 and p53 protein levels were abolished when cSrc was knocked-down. FA also increased NF-κB nuclear translocation and binding onto the p53 promoter. The FA-induced up-regulation of the p53 promoter activity was prevented by knocked-down of ERK. Matrigel angiogenesis assay in mice demonstrate the anti-angiogenic effect of FA in vivo. In conclusion, our data indicate that FA bound to FR in HUVEC, subsequently activated the cSrc/ERK 2/NF-κB/p53 signaling pathway, which in turn up-regulated the expression of p21 and p27, and finally resulted in cell cycle arrest at the G0/G1 phase. In the present study, we uncover a completely novel role of FA for anti-angiogenesis.

Bacterial Folates Provide an Exogenous Signal for C. elegans Germline Stem Cell Proliferation

“…The addition of folates to cells activates intracellular signaling pathways in a FR-dependent manner in time periods that are shorter than would be expected from changes in one-carbon metabolism. The addition of folic acid to mammalian cells has been reported to induce the phospho-activation of c-src tyrosine kinase, ERK kinase, and STAT transcription factor in a FRα-dependent manner within 2–5 minutes of stimulation (Hansen et al, 2015; Lin et al, 2012; Zhang et al, 2009). Additionally, FRα itself has been reported to translocate to the nucleus and function as a transcription factor in human tissue culture cells after stimulation with 453 μM of folic acid (Boshnjaku et al, 2012).…”

Nutrition and Atherosclerosis

“…In this mechanism, folic acid binds to its receptor (folic acid receptor) and subsequently activates the extracellular-signal-regulated kinases/NFkB/-signaling pathway which, in turn, upregulates the expression of p21 and p27 and finally results in cell cycle arrest at the G0/G1 phase inhibiting vascular endothelial cell proliferation (160).…”

“…Plasma total homocysteine is associated with an increased risk of coronary artery disease (176). Folic acid is the fully oxidized monoglutamyl form of folate and is frequently used as the nutritional supplement of folate due to its stability and bioavailability (160). Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of eNOS, the enzyme catalyzing the formation of NO, and is a mediator of atherogenic effects of homocysteine.…”

“…Most mammals are unable to produce folate except for the novo synthesis by intestinal microbiota. Therefore, the daily requirement must be obtained from dietary or supplementary sources (160). Tetrahydrofolate is the active form of folate and functions in the production of purines, pyrimidines and the remethylation of homocysteine to methionine.…”

Folate deficiency and aberrant DNA methylation and expression of FHIT gene were associated with cervical pathogenesis

“…Our results based on the population and in vitro studies showed that levels of RBC folate were decreased with the severity of cervical lesions, proliferation inhibition rate and apoptosis rate gradually increased in CC cells (HPV16 positive or negative) with the increasing folate concentrations. Shyr and colleagues (28) reported folic acid (0-10 µmol/l) concentration-dependently decreased DNA synthesis and proliferation in cultured human umbilical venous endothelial cells (HUVEC). Other research have shown that folic acid can promote dose dependent cell proliferation in folate receptor α (FRα)-positive HeLa cells, but not in FRα-negative HEK293 cells (29).…”