Acquired AKT-inhibitor Resistance Is Mediated by ATP-binding Cassette Transporters in Endometrial Carcinoma

Abstract

Background/Aim: Endometrial cancer is increasing in prevalence worldwide. It is treated with chemotherapy and radiotherapy, in addition to surgery, but the presence of treatment-resistant tumor cells remains a barrier to effective tumor control. The purpose of this study was to develop drug-resistant cell lines using triciribine, an AKT inhibitor, and investigate the mechanism of acquired resistance. Materials and Methods: Triciribine sensitivity assays were performed using Cell Counting Kit-8 (CCK-8) on eight endometrial cancer cell lines. The chosen cell lines were highly sensitive to chemotherapy and radiotherapy. A new triciribine-resistant cell line was established and found to be highly resistant to chemotherapy. Properties of the resistant cell line were identified using molecular and cell biological techniques including CCK-8 and quantitative PCR analysis. Results: HEC-151 had the highest triciribine sensitivity (IC₅₀ value of 0.7±0.1 μM) of the endometrial cancer cell lines tested. We established a triciribine-resistant cell line from HEC-151 by growing cells in the presence of increasing concentrations of triciribine up to 66.6 μM. The resistant HEC-151 cells changed to spindle-shaped morphology and importantly reduced triciribine sensitivity compared to the parental cell line. ABC transporters involved in drug efflux had significantly higher expression levels in ABCB1 (1.4±0.10 times higher), ABCC1 (11.4±0.22 times higher), and ABCC4 (4.5±0.42 times higher). Conclusion: In this study, we established a triciribine-resistant cell line from HEC-151 cells. Our data suggest that the mechanism of drug resistance in endometrial cancer cells is attributed to the increased expression of ABC transporters.