The high prevalence of KRAS mutations in pancreatic cancer (PC) is widely acknowledged and results in the resistance of targeted ferroptosis therapy and immunotherapy. Herein, via a CRISPR/Cas9 library screen, the effects of ferroptosis agonists were increased in KRAS-mutant PC cells upon knockout of tropomodulin 3 (TMOD3), while these effects were not observed in KRAS-wild-type cells. Increased levels of TMOD3 were found in PC tissues, particularly in those with KRAS mutations. The increase in TMOD3 expression was facilitated by KRAS via the ETS transcription factor ELK1. Liquid chromatography–mass spectrometry (LC/MS) showed that TMOD3 increased acyl-CoA synthetase long chain family member 4 (ACSL4) protein expression and fatty acid metabolism. Mechanistically, TMOD3 promoted F-actin polymerization, thereby facilitating the fusion of autophagosomes with lysosomes, increasing the degradation of the ACSL4 protein, and augmenting the ferroptosis-inducing effects of RSL3. These effects of TMOD3 were counteracted by the administration of cytochalasin, the removal of the α2 domain of TMOD3, or the introduction of a mutation at S71. Cangrelor, an FDA-approved drug, can target TMOD3. In a mouse model, the suppression of TMOD3 using cangrelor or gene silencing technology resulted in increased infiltration of CD8+ T cells into tumor tissues with KRAS mutations and exhibited a synergistic effect with the PD-1 antibody. In conclusion, TMOD3 was found to inhibit ferroptosis and induced the resistance to PD-1 antibody by facilitating the fusion of autophagosomes and lysosomes through the promotion of F-actin polymerization in KRAS-mutant PC. TMOD3 was identified as a novel target for PC therapy.

中文翻译：

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TMOD3 通过促进 ASCL4 的自噬依赖性降解加速 KRAS 突变胰腺癌对免疫治疗的耐药性


胰腺癌 （PC） 中 KRAS 突变的高患病率已得到广泛认可，并导致靶向铁死亡治疗和免疫治疗的耐药性。在此，通过 CRISPR/Cas9 文库筛选，敲除原调节蛋白 3 （TMOD3） 后，铁死亡激动剂在 KRAS 突变型 PC 细胞中的作用增加，而在 KRAS 野生型细胞中未观察到这些作用。在 PC 组织中发现 TMOD3 水平升高，尤其是在具有 KRAS 突变的组织中。KRAS 通过 ETS 转录因子 ELK1 促进了 TMOD3 表达的增加。液相色谱-质谱 （LC/MS） 显示，TMOD3 增加了酰基辅酶 A 合成酶长链家族成员 4 （ACSL4） 蛋白表达和脂肪酸代谢。从机制上讲，TMOD3 促进 F-肌动蛋白聚合，从而促进自噬体与溶酶体的融合，增加 ACSL4 蛋白的降解，并增强 RSL3 的铁死亡诱导作用。TMOD3 的这些作用被细胞松弛素的施用、去除 TMOD3 的 α 2 结构域或在 S71 处引入突变所抵消。Cangrelor是一种经FDA批准的药物，可以靶向TMOD3。在小鼠模型中，使用坎格雷洛或基因沉默技术抑制 TMOD3 导致 CD8+ T 细胞浸润到 KRAS 突变的肿瘤组织中增加，并与 PD-1 抗体表现出协同作用。总之，发现 TMOD3 通过促进 KRAS 突变 PC 中的 F-肌动蛋白聚合促进自噬体和溶酶体的融合，从而抑制铁死亡并诱导对 PD-1 抗体的耐药。TMOD3 被确定为 PC 治疗的新靶点。