Department of Biochemistry (Sector 25), Panjab University, Chandigarh 160014, India.
Department of Medicine, Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
J Steroid Biochem Mol Biol. 2024 Oct;243:106572. doi: 10.1016/j.jsbmb.2024.106572. Epub 2024 Jun 21.
Aberrant cholesterol homeostasis is a well-recognized hallmark of cancer and is implicated in metastasis as well as chemotherapeutic resistance, the two major causes of cancer associated mortality. Liver X receptors (LXRs) are the key transcription factors that induce cholesterol efflux via enhancing the expression of ABCA1 and ABCG1. Therefore, a comprehensive analysis of several novel sterols namely ergosta-7,22,24(28)-trien-3β-ol (Erg1), ergosta-5,22,25-trien-3-ol (Erg2), ergosta-5,7,22,24(28)-tetraen-3β-ol (Erg3), and ergosta-7,22-dien-3β-ol (Erg4) as LXR agonists has been performed. Molecular docking studies have shown that these sterols possess higher binding affinities for LXRs as compared to the reference ligands (GW3965 and TO901317) and also formed critical activating interactions. Molecular dynamic (MD) simulations further confirmed that docking complexes made of these sterols possess significant stability. To assess the extent of LXR activation, ABCA1 promoter was cloned into luciferase reporter plasmid and transfected into HCT116 cells. It was observed that treatment with Erg, Erg2 and Erg4 led to a significant LXR activation with an EC of 5.64 µM, 4.83 and 3.03 µM respectively. Furthermore, a significant increase in mRNA expression of NR1H2 and LXR target genes i.e. ABCA1, ABCG1 and ApoE was observed upon Erg treatment. Flow cytometric analysis have revealed a significant increase in the accumulation of ABCA1 upon Erg treatment. Cytotoxicity studies conducted on colorectal cancer cell and normal epithelial cell line showed that these sterols are selectively toxic towards cancer cells. Taken together, our findings suggests that ergosterol activates LXRs, have significant anticancer activity and could be a likely candidate to manage aberrant cholesterol homeostasis.
胆固醇代谢失衡是癌症的一个公认特征，与癌症相关死亡率的两个主要原因——转移和化疗耐药密切相关。肝 X 受体（LXRs）是关键的转录因子，通过增强 ABCA1 和 ABCG1 的表达来诱导胆固醇外排。因此，我们对几种新型固醇，即麦角甾-7,22,24(28)-三烯-3β-醇（Erg1）、麦角甾-5,22,25-三烯-3-醇（Erg2）、麦角甾-5,7,22,24(28)-四烯-3β-醇（Erg3）和麦角甾-7,22-二烯-3β-醇（Erg4）作为 LXR 激动剂进行了全面分析。分子对接研究表明，与参比配体（GW3965 和 TO901317）相比，这些固醇对 LXR 具有更高的结合亲和力，并且形成了关键的激活相互作用。分子动力学（MD）模拟进一步证实，这些固醇形成的对接复合物具有显著的稳定性。为了评估 LXR 激活的程度，将 ABCA1 启动子克隆到荧光素酶报告质粒中，并转染到 HCT116 细胞中。结果表明，Erg、Erg2 和 Erg4 处理导致 LXR 显著激活，EC50 值分别为 5.64µM、4.83µM 和 3.03µM。此外，Erg 处理后观察到 NR1H2 和 LXR 靶基因，即 ABCA1、ABCG1 和 ApoE 的 mRNA 表达显著增加。流式细胞术分析显示 Erg 处理后 ABCA1 积累显著增加。对结直肠癌细胞和正常上皮细胞系进行的细胞毒性研究表明，这些固醇对癌细胞具有选择性毒性。总之，我们的研究结果表明麦角固醇激活 LXRs，具有显著的抗癌活性，可能是管理异常胆固醇代谢的候选药物。
