KRAS 突变经常发生在癌症中，特别是胰腺导管腺癌、结直肠癌和非小细胞肺癌。尽管 KRASG12C 抑制剂最近已获得批准，但尚未针对所有 KRAS 突变癌症建立有效的精准疗法。目前正在研究许多针对 KRAS 突变癌症的治疗方法，包括表观基因组靶向药物。小泛素样修饰剂 (SUMO) 蛋白是一类小蛋白，通过称为 SUMO 化和去 SUMO 化的过程与细胞中的其他蛋白共价连接和分离。我们评估了 SUMO 化抑制在 KRAS 突变癌细胞中是否有效。在多种人类和小鼠 KRAS 突变癌细胞系中评估了一流的 SUMO 激活酶 E 抑制剂 TAK-981 (subasumstat) 的功效。使用 TaqMan 阵列进行基因表达测定来鉴定 TAK-981 功效的生物标志物。使用免疫印迹分析、免疫荧光测定和小鼠模型研究了 SUMO 化抑制的生物学作用和随后的调节机制。我们发现 TAK-981 下调了目前不可成药的 MYC 的表达，并有效抑制了表达 MYC 的 KRAS 突变癌症的生长跨越不同的组织类型。此外，TAK-981 耐药细胞通过 MYC 过表达对 SUMO 化抑制敏感。 TAK-981 通过改变 SUMO 化和泛素化之间的平衡并促进 MYC 和 Fbxw7（泛素-蛋白酶体系统中的关键因素）的结合来诱导 MYC 的蛋白酶体降解。 TAK-981 单药疗法在使用小鼠来源的 CMT167 细胞系的免疫功能正常和免疫缺陷小鼠模型中的疗效显着但有限。由于 MAPK 抑制 KRAS 下游通路在 KRAS 突变癌症中至关重要，因此我们预计 SUMO 化和 MEK 的共同抑制可能是一个不错的选择。令人惊讶的是，TAK-981 和曲美替尼联合治疗可显着诱导多种细胞系和基因工程小鼠衍生类器官的细胞凋亡。此外，联合疗法在使用不同组织类型细胞系的小鼠模型中导致了长期肿瘤消退。最后，我们发现联合疗法可以互补地抑制 Rad51 和 BRCA1 并累积 DNA 损伤。我们发现，在 KRAS 突变癌细胞中，MYC 下调是通过 SUMOylation 抑制而发生的。我们的研究结果表明，SUMOylation 和 MEK 的双重抑制可能通过增强 DNA 损伤累积来治疗表达 MYC 的 KRAS 突变癌症。© 2024。作者。

KRAS mutations frequently occur in cancers, particularly pancreatic ductal adenocarcinoma, colorectal cancer, and non-small cell lung cancer. Although KRASG12C inhibitors have recently been approved, effective precision therapies have not yet been established for all KRAS-mutant cancers. Many treatments for KRAS-mutant cancers, including epigenome-targeted drugs, are currently under investigation. Small ubiquitin-like modifier (SUMO) proteins are a family of small proteins covalently attached to and detached from other proteins in cells via the processes called SUMOylation and de-SUMOylation. We assessed whether SUMOylation inhibition was effective in KRAS-mutant cancer cells.The efficacy of the first-in-class SUMO-activating enzyme E inhibitor TAK-981 (subasumstat) was assessed in multiple human and mouse KRAS-mutated cancer cell lines. A gene expression assay using a TaqMan array was used to identify biomarkers of TAK-981 efficacy. The biological roles of SUMOylation inhibition and subsequent regulatory mechanisms were investigated using immunoblot analysis, immunofluorescence assays, and mouse models.We discovered that TAK-981 downregulated the expression of the currently undruggable MYC and effectively suppressed the growth of MYC-expressing KRAS-mutant cancers across different tissue types. Moreover, TAK-981-resistant cells were sensitized to SUMOylation inhibition via MYC-overexpression. TAK-981 induced proteasomal degradation of MYC by altering the balance between SUMOylation and ubiquitination and promoting the binding of MYC and Fbxw7, a key factor in the ubiquitin-proteasome system. The efficacy of TAK-981 monotherapy in immunocompetent and immunodeficient mouse models using a mouse-derived CMT167 cell line was significant but modest. Since MAPK inhibition of the KRAS downstream pathway is crucial in KRAS-mutant cancer, we expected that co-inhibition of SUMOylation and MEK might be a good option. Surprisingly, combination treatment with TAK-981 and trametinib dramatically induced apoptosis in multiple cell lines and gene-engineered mouse-derived organoids. Moreover, combination therapy resulted in long-term tumor regression in mouse models using cell lines of different tissue types. Finally, we revealed that combination therapy complementally inhibited Rad51 and BRCA1 and accumulated DNA damage.We found that MYC downregulation occurred via SUMOylation inhibition in KRAS-mutant cancer cells. Our findings indicate that dual inhibition of SUMOylation and MEK may be a promising treatment for MYC-expressing KRAS-mutant cancers by enhancing DNA damage accumulation.© 2024. The Author(s).