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Abstract：
BACKGROUND: While de novo cholesterol biosynthesis plays a crucial role in chemotherapy resistance of colorectal cancer (CRC), the underlying molecular mechanism remains poorly understood.
METHODS: We conducted cell proliferation assays on CRC cells with or without depletion of squalene epoxidase (SQLE), with or without 5-fluorouracil (5-FU) treatment. Additionally, a xenograft mouse model was utilized to explore the impact of SQLE on the chemosensitivity of CRC to 5-FU. RNA-sequencing analysis and immunoblotting analysis were performed to clarify the mechanism. We further explore the effect of SQLE depletion on the ubiquitin of NF-κB inhibitor alpha (IκBα) and (S)-2,3-epoxysqualene on the binding of IκBα to beta-transducin repeat containing E3 ubiquitin protein ligase (BTRC) by using immunoprecipitation assay. In addition, a cohort of 272 CRC patients were selected for our clinical analyses.
RESULTS: Mechanistically, (S)-2,3-epoxysqualene promotes IκBα degradation and subsequent NF-κB activation by enhancing the interaction between BTRC and IκBα. Activated NF-κB upregulates the expression of baculoviral IAP repeat containing 3 (BIRC3), sustains tumor cell survival after 5-FU treatment and promotes 5-FU resistance of CRC in vivo. Notably, the treatment of terbinafine, an inhibitor of SQLE commonly used as antifungal drug in clinic, enhances the sensitivity of CRC to 5-FU in vivo. Additionally, the expression of SQLE is associated with the prognosis of human CRC patients with 5-FU-based chemotherapy.
CONCLUSIONS: Thus, our finding not only demonstrates a new role of SQLE in chemoresistance of CRC, but also reveals a novel mechanism of (S)-2,3-epoxysqualene-dependent NF-κB activation, implicating the combined potential of terbinafine for 5-FU-based CRC treatment.
METHODS: We conducted cell proliferation assays on CRC cells with or without depletion of squalene epoxidase (SQLE), with or without 5-fluorouracil (5-FU) treatment. Additionally, a xenograft mouse model was utilized to explore the impact of SQLE on the chemosensitivity of CRC to 5-FU. RNA-sequencing analysis and immunoblotting analysis were performed to clarify the mechanism. We further explore the effect of SQLE depletion on the ubiquitin of NF-κB inhibitor alpha (IκBα) and (S)-2,3-epoxysqualene on the binding of IκBα to beta-transducin repeat containing E3 ubiquitin protein ligase (BTRC) by using immunoprecipitation assay. In addition, a cohort of 272 CRC patients were selected for our clinical analyses.
RESULTS: Mechanistically, (S)-2,3-epoxysqualene promotes IκBα degradation and subsequent NF-κB activation by enhancing the interaction between BTRC and IκBα. Activated NF-κB upregulates the expression of baculoviral IAP repeat containing 3 (BIRC3), sustains tumor cell survival after 5-FU treatment and promotes 5-FU resistance of CRC in vivo. Notably, the treatment of terbinafine, an inhibitor of SQLE commonly used as antifungal drug in clinic, enhances the sensitivity of CRC to 5-FU in vivo. Additionally, the expression of SQLE is associated with the prognosis of human CRC patients with 5-FU-based chemotherapy.
CONCLUSIONS: Thus, our finding not only demonstrates a new role of SQLE in chemoresistance of CRC, but also reveals a novel mechanism of (S)-2,3-epoxysqualene-dependent NF-κB activation, implicating the combined potential of terbinafine for 5-FU-based CRC treatment.
摘要：
背景：虽然从头胆固醇生物合成在结直肠癌（CRC）的化疗耐药中起着至关重要的作用，潜在的分子机制仍然知之甚少。
方法：我们在使用或不使用角鲨烯环氧酶（SQLE）的情况下对CRC细胞进行了细胞增殖测定，有或没有5-氟尿嘧啶（5-FU）治疗。此外,使用异种移植小鼠模型来探索SQLE对CRC对5-FU的化学敏感性的影响。进行RNA测序分析和免疫印迹分析以阐明机制。我们进一步探讨了SQLE耗竭对NF-κB抑制剂α（IκBα）和（S）-2,3-环氧角鲨烯的泛素对IκBα与包含E3泛素蛋白连接酶（BTRC）的β转导蛋白重复结合的影响。此外,我们选择了272例CRC患者进行临床分析.
结果：机械，（S）-2,3-环氧角鲨烯通过增强BTRC与IκBα之间的相互作用来促进IκBα降解和随后的NF-κB激活。激活的NF-κB上调杆状病毒IAP重复序列3（BIRC3）的表达，维持5-FU治疗后的肿瘤细胞存活，并在体内促进CRC的5-FU抗性。值得注意的是,特比萘芬的治疗，一种临床上常用抗真菌药物的SQLE抑制剂，在体内增强CRC对5-FU的敏感性。此外,SQLE的表达与以5-FU为基础的化疗的人类CRC患者的预后相关。
结论：因此，我们的发现不仅证明了SQLE在CRC化学耐药中的新作用，而且还揭示了（S）-2,3-环氧角鲨烯依赖性NF-κB激活的新机制，涉及特比萘芬用于基于5-FU的CRC治疗的联合潜力。
方法：我们在使用或不使用角鲨烯环氧酶（SQLE）的情况下对CRC细胞进行了细胞增殖测定，有或没有5-氟尿嘧啶（5-FU）治疗。此外,使用异种移植小鼠模型来探索SQLE对CRC对5-FU的化学敏感性的影响。进行RNA测序分析和免疫印迹分析以阐明机制。我们进一步探讨了SQLE耗竭对NF-κB抑制剂α（IκBα）和（S）-2,3-环氧角鲨烯的泛素对IκBα与包含E3泛素蛋白连接酶（BTRC）的β转导蛋白重复结合的影响。此外,我们选择了272例CRC患者进行临床分析.
结果：机械，（S）-2,3-环氧角鲨烯通过增强BTRC与IκBα之间的相互作用来促进IκBα降解和随后的NF-κB激活。激活的NF-κB上调杆状病毒IAP重复序列3（BIRC3）的表达，维持5-FU治疗后的肿瘤细胞存活，并在体内促进CRC的5-FU抗性。值得注意的是,特比萘芬的治疗，一种临床上常用抗真菌药物的SQLE抑制剂，在体内增强CRC对5-FU的敏感性。此外,SQLE的表达与以5-FU为基础的化疗的人类CRC患者的预后相关。
结论：因此，我们的发现不仅证明了SQLE在CRC化学耐药中的新作用，而且还揭示了（S）-2,3-环氧角鲨烯依赖性NF-κB激活的新机制，涉及特比萘芬用于基于5-FU的CRC治疗的联合潜力。
