| Cigarette smoking in women has been linked with a decreased incidence of endometrial cancer and endometriosis, whereas exposure to the dioxin 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has been associated with an increased incidence of endometriosis in animal models. This study elucidated the cellular and molecular effects of BaP, a cigarette smoke toxicant, and dioxin, on three human, uterine endometrial cancer cell lines (RL95-2, HEC-1A, and HEC-1B).; Experiments show that BaP completely inhibited RL95-2 and HEC-1A cellular attachment and caused a marked decrease in membrane β-catenin and EGF-R protein levels, whereas HEC-1B cells were unaffected. TCDD did not affect attachment, β-catenin, or EGF-R levels in RL95-2 cells. BaP, but not TCDD, further produced subcortical actin aggregates and decreased cadherin levels in RL95-2 cells, whereas actin and vinculin levels remained unchanged.; HEC-1A (BaP-responsive) and HEC-1B (BaP-unresponsive) cells were investigated for key morphological differences. HEC-1A cells expressed higher levels of α-catenin than HEC-1B cells. Further, HEC-1A cells have thick, cortical, filamentous actin, whereas HEC-1B cells exhibit nuclear-localized actin and non-continuous intercellular boundaries. Upon BaP treatment, HEC-1A cells show decreased α-catenin, β-catenin, and EGF-R protein levels. HEC-1B cells were unaffected by BaP treatment. Furthermore, BaP, but not TCDD, treatment produced an enhanced S and G2M phase response in HEC-1A and RL95-2, but not HEC-1B cells.; CYP1A1 and CYP1B1 induction were found to be consistent in all cell lines upon BaP and TCDD treatment, and therefore do not account for the cell-specific and BaP-specific effects. However, PGHS-1 protein expression was increased by 150% upon BaP, but not TCDD treatment in RL95-2 cells. Microarray experiments defined the distinct molecular fingerprints for BaP-mediated changes in gene expression in HEC-1A and HEC-1B cell lines, as well as for BaP, TCDD, and t-butylhydroperoxide effects on RL95-2 cells.; Overall, results show that the Ah-Receptor ligand BaP alters a complex array of signal transduction pathways in human endometrial adenocarcinoma cell lines, resulting in profound alterations in cellular adhesion, cytoskeleton, and cell cycle checkpoint responses. The endometrial cancer cell lines RL95-2, HEC-1A, and HEC-1B are shown to be useful models for differentiating alternate cellular responsiveness to xenobiotic exposure. |
