Curcumin stimulates angiogenesis through VEGF and expression of HLA-G in first-trimester human placental trophoblasts

Abstract

Curcumin has a protective role in placental diseases like preeclampsia and preterm birth. Very little is known about its functional effects on growth, angiogenesis, and epigenetic activities of human first trimester placenta. HTR8/SVneo trophoblasts cells were used as model for human first trimester placenta. Effects of curcumin (≥80%) in these cells were investigated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), radioactive thymidine uptake, quantitative real-time polymerase chain reaction (qRT-PCR), promoter DNA methylation, qRT-PCR array, tube formation, wound healing, and immunoblot assays. PC3 (prostate cancer), JEG-3 (trophoblast), and HMEC-1 (endothelial) cells were used as control in various experiments. Unlike in PC3 cells, curcumin stimulated growth, proliferation, and viability in HTR8/SVneo cells. Curcumin increased tube formation, and messenger RNA (mRNA) expression of angiogenic factors such as vascular endothelial growth factor A (VEGFA) and protein expression of proangiogenic factor VEGF receptor-2 and fatty acid-binding protein-4 (FABP4) in these cells. Curcumin-stimulated tube formation was associated with an increased expression of VEGFR2 and FABP4. The stimulatory effects of curcumin were inhibited by VEGFR2 (SU5416) and FABP4 (BMS309403) inhibitors. Curcumin also significantly increased both mRNA and protein expression of HLA-G in HTR8/SVneo cells. Curcumin increased mRNA expression of DNMT3A and NOTCH signaling system whereas down-regulated mRNA expression of HSD11β2. Curcumin enhanced hypomethylation of gene promoters against oxidative stress and DNA damage pathway mediators. Curcumin promotes cell growth, migration, and thus angiogenic potential of these cells. Increased expression of HLA-G by curcumin, hitherto unknown, is a novel finding since HLA-G not only favors the immune environment for invasive trophoblasts but also positively modulates angiogenesis.

Keywords: 3H-Thymidine assay; DNA methylation tube formation; EpiTect methyl PCR arrays; FABP4; HLA-G; HTR8/SVneo; PC-3 cells; VEGFA; VEGFR2; curcumin; real-time PCR-array; trophoblasts; wound healing.