PI3 kinase mediates bile salt induced proliferation in a telomerase-immortalized Barrett’s cell line

Abstract

Abstract Introduction: Bile exposure is implicated in the malignant progression of Barrett's esophagus. Our previous studies demonstrated that bile salt exposure in a Barrett's adenocarcinoma cell line induces proliferation by activating the PI3 kinase/Akt pathway. However, it is not clear that these findings in cancer cells are applicable to the non-neoplastic cells of Barrett's esophagus. Therefore, we studied the effects of bile on PI3 kinase activation and proliferation in a novel, telomerase-immortalized, non-neoplastic Barrett's cell line. Methods: A human, telomerase-immortalized Barrett's cell line (BAR D2847 hTERT lox) was exposed to the conjugated bile salt glycochenodeoxycholic acid (GCDA) at neutral pH. Proliferation was measured by the MTT incorporation assay and Coulter counter. PI3 kinase activity was inferred from western blots for phosphorylated (active form) and total Akt, the major down-stream effector of PI3 kinase. LY294002, a PI3 kinase inhibitor, was used to block the PI3 kinase/Akt pathway. Results: A 5-minute exposure to the clinically relevant concentration of 200uM GCDA produced a 50% cell number increase (P Conclusions: Conjugated bile salts stimulate proliferation in a non-neoplastic Barrett's cell line in a PI3 kinase dependent fashion. We propose that bile exposure acts as a growth signal in the early stages of non-neoplastic Barrett's, thereby promoting progression to adenocarcinoma.