Mitotane causes hypercholesterolemia in patients with adrenocortical carcinoma (ACC). We suppose that cholesterol increases within the tumor and can be used to activate proliferative pathways. In this study, we used statins to decrease intratumor cholesterol and investigated the effects on ACC growth related to estrogen receptor α (ERα) action at the nuclear and mitochondrial levels. We first used microarray to investigate mitotane effect on genes involved in cholesterol homeostasis and evaluated their relationship with patients' survival in ACC TCGA. We then blocked cholesterol synthesis with simvastatin and determined the effects on H295R cell proliferation, estradiol production, and ERα activity in vitro and in xenograft tumors. We found that mitotane increases intratumor cholesterol content and expression of genes involved in cholesterol homeostasis, among them INSIG, whose expression affects patients' survival. Treatment of H295R cells with simvastatin to block cholesterol synthesis decreased cellular cholesterol content, and this affected cell viability. Simvastatin reduced estradiol production and decreased nuclear and mitochondrial ERα function. A mitochondrial target of ERα, the respiratory complex IV (COXIV), was reduced after simvastatin treatment, which profoundly affected mitochondrial respiration activating apoptosis. Additionally, simvastatin reduced tumor volume and weight of grafted H295R cells, intratumor cholesterol content, Ki-67 and ERα, COXIV expression and activity and increase terminal deoxynucleotidyl transferase dUTP nick end labeling–positive cells. Collectively, these data demonstrate that a reduction in intratumor cholesterol content prevents estradiol production and inhibits mitochondrial respiratory chain–inducing apoptosis in ACC cells. Inhibition of mitochondrial respiration by simvastatin represents a novel strategy to counteract ACC growth.

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他汀类药物降低影响肾上腺皮质癌生长的肿瘤内胆固醇

米托坦会导致肾上腺皮质癌 (ACC) 患者出现高胆固醇血症。我们假设肿瘤内的胆固醇增加，可用于激活增殖途径。在这项研究中，我们使用他汀类药物降低肿瘤内胆固醇，并研究了与核和线粒体水平的雌激素受体 α (ERα) 作用相关的 ACC 生长的影响。我们首先使用微阵列来研究米托坦对参与胆固醇稳态的基因的影响，并评估它们与 ACC TCGA 患者存活率的关系。然后，我们用辛伐他汀阻断胆固醇合成，并在体外和异种移植肿瘤中确定对 H295R 细胞增殖、雌二醇产生和 ERα 活性的影响。我们发现米托坦增加肿瘤内胆固醇含量和参与胆固醇稳态的基因表达，其中包括 INSIG，其表达影响患者的生存。用辛伐他汀处理 H295R 细胞以阻断胆固醇合成会降低细胞胆固醇含量，这会影响细胞活力。辛伐他汀减少雌二醇的产生并降低核和线粒体 ERα 功能。辛伐他汀治疗后，ERα 的线粒体靶点呼吸复合体 IV (COXIV) 减少，这对激活细胞凋亡的线粒体呼吸产生了深远的影响。此外，辛伐他汀降低了移植 H295R 细胞的肿瘤体积和重量、肿瘤内胆固醇含量、Ki-67 和 ERα，COXIV 表达和活性并增加末端脱氧核苷酸转移酶 dUTP 缺口末端标记阳性细胞。总的来说，这些数据表明肿瘤内胆固醇含量的降低阻止了雌二醇的产生并抑制了线粒体呼吸链诱导的 ACC 细胞凋亡。辛伐他汀对线粒体呼吸的抑制代表了一种抵消 ACC 生长的新策略。