The Variability of oxLDL-induced Cytotoxicity on Different Types of Cell Lines

The epidemiologic studies indicated an association of obesity with increased incidence of colorectal, breast and ovarian cancer. Further studies found a positive correlation between increased serum oxLDL and an increased risk of the three cancers. In contrast, our previous studies found a negative correlation between the serum oxLDL levels and the risk of leukemia and esophageal cancer. Identification of the variability of cytotoxicity of oxLDL-induced on different types of cell lines is important for understanding the mechanism of oxLDL involved in the tumorigenesis. In the present study, we investigated the effective impacts of oxLDL on the proliferation and apoptosis for the human umbilical vein endothelial cells (HUVEC) and two cancer cell lines (EC-9706 and K562/AO2 with multi-drug resistance). HUVEC, K562/AO2 and EC-9706 cell lines were cultured in the presence of oxLDL, and cell proliferation was tested by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, apoptosis and cell cycle by flow cytometer, mRNA expression by RT-PCR and protein expression by Western blot. OxLDL could inhibit proliferation and apoptosis of the three cell lines; however, there were significant differences of effective action on the viability and apoptosis. The dose of oxLDL-induced cytotoxicity on HUVEC was higher than that on the two tumor cells. The antibody of lectin-like oxLDL receptor-1 (LOX-1-ab) can block oxLDL-induced cytotoxicity. Cells apoptosis is mediated by reducing Bcl-2 and increasing Bax and caspase-3 mRNA and protein expression. This study showed the dose of oxLDL-induced cytotoxicity on HUVEC was higher than that on K562/AO2 and EC-9706 tumor cells. The antibody of LOX-1 receptor can block the oxLDL-induced cytotoxicity.