Warde Kate M, Schoenmakers Erik, Ribes Martinez Eduardo, Lim Yi Jan, Leonard Maeve, Lawless Sarah J, O'Shea Paula, Chatterjee Krishna V, Gurnell Mark, Hantel Constanze, Dennedy Michael Conall
Discipline of Pharmacology and Therapeutics, School of Medicine, National University of Ireland, Galway, Ireland.
Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science-University of Cambridge and National Institute for Health Research Cambridge Biomedical Research Centre, Addenbrooke's Hospital, Cambridge, UK.
Endocr Relat Cancer. 2020 Jun;27(6):361-373. doi: 10.1530/ERC-20-0031.
Adrenocortical carcinoma (ACC) is a rare aggressive malignancy with a poor outcome largely due to limited treatment options. Here, we propose a novel therapeutic approach through modulating intracellular free cholesterol via the liver X receptor alpha (LXRα) in combination with current first-line pharmacotherapy, mitotane. H295R and MUC-1 ACC cell lines were pretreated with LXRα inhibitors in combination with mitotane. In H295R, mitotane (20, 40 and 50 µM) induced dose-dependent cell death; however, in MUC-1, this only occurred at a supratherapeutic concentration (200 µM). LXRα inhibition potentiated mitotane-induced cytotoxicity in both cell lines. This was confirmed through use of the CompuSyn model which showed moderate pharmacological synergism and was indicative of apoptotic cell death via an increase in annexinV and cleaved-caspase 3 expression. Inhibition of LXRα was confirmed through downregulation of cholesterol efflux pumps ABCA1 and ABCG1; however, combination treatment with mitotane attenuated this effect. Intracellular free-cholesterol levels were associated with increased cytotoxicity in H295R (r2 = 0.5210) and MUC-1 (r2 = 0.9299) cells. While both cell lines exhibited similar levels of free cholesterol at baseline, H295R were cholesterol ester rich, whereas MUC-1 were cholesterol ester poor. We highlight the importance of LXRα mediated cholesterol metabolism in the management of ACC, drawing attention to its role in the therapeutics of mitotane sensitive tumours. We also demonstrate significant differences in cholesterol storage between mitotane sensitive and resistant disease.
肾上腺皮质癌（ACC）是一种罕见的侵袭性恶性肿瘤，预后较差，主要原因是治疗选择有限。在此，我们提出一种新的治疗方法，即通过肝脏X受体α（LXRα）调节细胞内游离胆固醇，并结合目前的一线药物米托坦进行治疗。H295R和MUC-1 ACC细胞系先用LXRα抑制剂联合米托坦进行预处理。在H295R细胞中，米托坦（20、40和50 μM）诱导剂量依赖性细胞死亡；然而，在MUC-1细胞中，这仅在超治疗浓度（200 μM）时发生。LXRα抑制增强了两种细胞系中米托坦诱导的细胞毒性。这通过使用CompuSyn模型得到证实，该模型显示出适度的药理协同作用，并通过膜联蛋白V和裂解的半胱天冬酶3表达增加表明细胞凋亡死亡。通过下调胆固醇流出泵ABCA1和ABCG1证实了LXRα的抑制；然而，米托坦联合治疗减弱了这种作用。细胞内游离胆固醇水平与H295R（r2 = 0.5210）和MUC-1（r2 = 0.9299）细胞中细胞毒性增加相关。虽然两种细胞系在基线时游离胆固醇水平相似，但H295R富含胆固醇酯，而MUC-1则缺乏胆固醇酯。我们强调LXRα介导的胆固醇代谢在ACC治疗中的重要性，提请注意其在米托坦敏感肿瘤治疗中的作用。我们还证明了米托坦敏感和耐药疾病之间胆固醇储存的显著差异。
