663 Specific polycyclic aromatic hydrocarbons elicit differential expression of CYP1A1 in trophoblast cells

Abstract

Prenatal exposures to polycyclic aromatic hydrocarbons (PAHs) are associated with adverse outcomes including small for gestational age infants. We have previously reported differential levels of PAHs in the placenta associated with preterm delivery. We found that levels of a specific PAH, dibenzoanthracene (DBA), was significantly higher than levels of either benzo[a]pyrene (BaP) or Benzo[b]fluoranthene (BbF). Furthermore, we reported that placental DBA levels are significantly and negatively correlated with gestational age at delivery. In this study we aimed to determine if there is a differential response in trophoblast cells with distinct PAH treatments. Immortalized choriocarcinoma cells (BeWo) were treated with 10 μM of either BaP, BbF or DBA for 24 hours. DMSO treatment served as a control. Media was collected and measured to determine levels of hCG production using an ELISA assay. RNA was extracted from cells after 24 hours of treatment, and used to make cDNA. TaqMan primers and probes were used to measure expression levels of CYP1A1, a gene involved in the processing of xenobiotic compounds, using RT-qPCR. GAPDH served as a control. While treatment with each PAH increased CYP1A1 expression compared with DMSO, DBA elicited the largest response, with a 54-fold increase in CYP1A1 expression (p<0.001). CYP1A1 expression was increased 16.5-fold with BbF treatment (p=0.001), and 7.4-fold with BaP treatment (p=0.006). Levels of hCG were not altered with any PAH treatment compared with DMSO, consistent with previous publications in trophoblast cells. In placenta tissue, levels of DBA are found at higher levels compared with BaP and BbF, and DBA levels are increased in placentae from preterm birth. In this study we find that DBA elicits a higher upregulation of CYP1A1 compared with BaP and BbF. Further experimentation is necessary using RNA-Seq analyses to help yield insight into pathways differentially responsive to DBA, yielding insight into its association with preterm delivery.