217 THE EXPRESSION OF β-OXIDATION RELATING GENES UNDER HYPOXIC STRESS IN HUMAN PLACENTAL CHORIOCARCINOMA CELL (BeWo)

Abstract

Preeclampsia (PE) is thought in many cases to be caused by a shallowly implanted placenta that becomes hypoxic. Hypoxia can result from a failure at any stage in the delivery of oxygen to the cells. In peripheral tissues, oxygen diffuses down a pressure gradient into cells and moves into their mitochondria, where it is used to produce energy in conjunction with the breakdown of glucose, fats, and some amino acids. The aim of the study was to investigate the question of whether hypoxic stress is involved in β-oxidation of human placental BeWo cells. One of the β-oxidation related genes, ACADVL was detected by gene-fishing technology using the preeclamptic placenta of human. We conducted in vitro experiments to confirm a preliminary study by inducing hypoxic stress in the human placental BeWo cell. BeWo cells were cultured at 37°C in a 20% O₂, 5% CO₂ humidified tissue culture incubator. And then we induced hypoxic stress in BeWo cell cultured under 1% O₂, 5% CO₂, and balanced with N_2. The BeWo cells were divided into three groups: normoxia, hypoxia 24 h, and hypoxia 48 h. The expression of β-oxidation related genes (ACADVL, EHHADH, HADH, ACAA) were observed under hypoxic condition in BeWo cells by using real-time RT-PCR. Relative quantification with HPRT1 was based on the comparison of CT at a constant fluorescent intensity. The amount of transcript is inversely related to the observed CT, and for every 2-fold dilution in the transcript, CT is expected to increase by 1. Relative expression was calculated using the equation R = 2^{–(CTsample – CTcontrol)}. Data were analysed with a nonparametric one-way ANOVA, followed by Tukey's test for multiple comparisons. All statistical analyses were performed using GraphPad Prism software (v 4.0, GraphPad Software, La Jolla, CA, USA). P-values <0.05 were considered statistically significant. The expression of a gene known as a biomarker for hypoxia, HIF-1a, was significantly increased in BeWo cells which induced preeclampsia. The elevated level of HIF-1a indicates that our experimental conditions closely mimicked preeclampsia. The β-oxidation related genes, ACADVL, EHHADH, and HADH expressions were significantly increased under hypoxic condition in BeWo compared with normoxic control. These results indicate that changes of β-oxidation related genes observed under hypoxic BeWo cells are similar to ones associated with preeclampsia, and the expression of β-oxidation related genes were up-regulated by hypoxic stress. They might be involved in pathogenesis of preeclampsia during gestation. Taken together, increase of β-oxidation-related genes under hypoxic stress may cause a compensation of energy metabolism deficiency through lipid metabolism.