Endoplasmic Reticulum Stress-induced Endothelial Dysfunction Promotes Neointima Formation after Arteriovenous Grafts in Mice on High-fat Diet.

OBJECTIVE: Endothelial dysfunction is one candidate for triggering neointima formation after arteriovenous grafts (AVGs), but the factors mediating this process are unclear. The purpose of this study was to investigate the role of endoplasmic reticulum stress (ERS)-induced endothelial dysfunction in neointima formation following AVGs in high-fat diet (HFD) mice. METHODS: CCAAT-enhancer-binding protein-homologous protein (CHOP) knockout (KO) mice were created. Mice were fed with HFD to produce HFD model. AVGs model were applied in the groups of WT ND, WT HFD, and CHOP KO HFD. Human umbilical vein endothelial cells (HUVECs) were cultured with oxidized low density lipoprotein (ox-LDL) (40 mg/L) for the indicated time lengths (0, 6, 12, 24 h). ERS inhibitor tauroursodeoxycholic acid (TUDCA) was used to block ERS. Immunohistochemical staining was used to observe the changes of ICAM1. Changes of ERS were detected by real-time RT-PCR. Protein expression levels and ERS activation were detected by Western blotting. Endothellial cell function was determined by endothelial permeability assay and transendothelial migration assay. RESULTS: HFD increased neointima formation in AVGs associated with endothelial dysfunction. At the same time, ERS was increased in endothelial cells (ECs) after AVGs in mice consuming the HFD. In vitro, ox-LDL was found to stimulate ERS, increase the permeability of the EC monolayer, and cause endothelial dysfunction. Blocking ERS with TUDCA or CHOP siRNA reversed the EC dysfunction caused by ox-LDL. In vivo, knockout of CHOP (CHOP KO) protected the function of ECs and decreased neointima formation after AVGs in HFD mice. CONCLUSION: Inhibiting ERS in ECs could improve the function of AVGs.

Cytotoxic Tricycloalternarene Compounds from Endophyte Alternaria sp. W-1 Associated with Laminaria japonica.

The chemical investigation of the culture filtrate of endophyte Alternaria sp. W-1 associated with Laminaria japonica provided a new tricycloalternarene compound, 2H-(2E)-tricycloalternarene 12a (1), together with five known analogs: (2E)-tricycloalternarene 12a (2), tricycloalternarene 3a (3), tricycloalternarene F (4), 15-hydroxyl tricycloalternarene 5b (5), and ACTG-Toxin D (6). In vitro cytotoxicity against the human hepatocellular carcinoma cell line SMMC-7721 and the human gastric carcinoma cell line SGC-7901 was evaluated by the MTT method. Compounds 1, 3, and 4 inhibited the growth of SMMC-7721 cells with IC50 values of 49.7 ± 1.1, 45.8 ± 4.6, and 80.3 ± 3.8 µg/mL, respectively, while the IC50 value of the positive control cisplatin was 6.5 ± 0.5 µg/mL. Compounds 3 and 6 also showed moderate anti-proliferation activity against SGC-7901 cells with IC50 values of 53.2 ± 2.9 and 35.1 ± 0.8 µg/mL, respectively, while the IC50 value of cisplatin was 4.5 ± 0.6 µg/mL. Further studies revealed that the in vitro anticancer activity of compound 3 to SMMC-7721 cells was related to G1 phase cell cycle arrest and cell apoptosis, and the induced apoptosis was involved in both the mitochondrial pathway and the death receptor pathway. This is the first report on the anticancer mechanism of tricycloalternarene compounds.