Digestive System Department, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, 362000, China.
Central Laboratory, The Second Affiliated Hospital of Fujian Medical University, No. 34, Zhongshan North Road, Licheng District, Quanzhou, 362000, China.
BMC Gastroenterol. 2024 Jul 29;24(1):239. doi: 10.1186/s12876-024-03321-9.
MutT homolog 1 (MTH1) sanitizes oxidized dNTP pools to promote the survival of cancer cells and its expression is frequently upregulated in cancers. Polyubiquitination stabilizes MTH1 to facilitate the proliferation of melanoma cells, suggesting the ubiquitin system controls the stability and function of MTH1. However, whether ubiquitination regulates MTH1 in gastric cancers has not been well defined. This study aims to investigate the interaction between MTH1 and a deubiquitinase, USP9X, in regulating the proliferation, survival, migration, and invasion of gastric cancer cells.
The interaction between USP9X and MTH1 was evaluated by co-immunoprecipitation (co-IP) in HGC-27 gastric cancer cells. siRNAs were used to interfere with USP9X expression in gastric cancer cell lines HGC-27 and MKN-45. MTT assays were carried out to examine the proliferation, propidium iodide (PI) and 7-AAD staining assays were performed to assess the cell cycle, Annexin V/PI staining assays were conducted to examine the apoptosis, and transwell assays were used to determine the migration and invasion of control, USP9X-deficient, and USP9X-deficient plus MTH1-overexpressing HGC-27 and MKN-45 gastric cancer cells.
Co-IP data show that USP9X interacts with and deubiquitinates MTH1. Overexpression of USP9X elevates MTH1 protein level by downregulating its ubiquitination, while knockdown of USP9X has the opposite effect on MTH1. USP9X deficiency in HGC-27 and MKN-45 cells causes decreased proliferation, cell cycle arrest, extra apoptosis, and defective migration and invasion, which could be rescued by excessive MTH1.
USP9X interacts with and stabilizes MTH1 to promote the proliferation, survival, migration and invasion of gastric cancer cells.
MutT 同源物 1（MTH1）可清除氧化的 dNTP 池，以促进癌细胞的存活，其表达在癌症中经常上调。多泛素化稳定 MTH1 以促进黑色素瘤细胞的增殖，这表明泛素系统控制着 MTH1 的稳定性和功能。然而，泛素化是否调节胃癌中的 MTH1 尚未得到很好的定义。本研究旨在探讨 MTH1 与去泛素化酶 USP9X 之间的相互作用，以调节胃癌细胞的增殖、存活、迁移和侵袭。
在 HGC-27 胃癌细胞中通过共免疫沉淀（co-IP）评估 USP9X 和 MTH1 之间的相互作用。使用 siRNA 干扰胃癌细胞系 HGC-27 和 MKN-45 中的 USP9X 表达。通过 MTT 测定法检测增殖，碘化丙啶（PI）和 7-AAD 染色测定法评估细胞周期，通过 Annexin V/PI 染色测定法检测凋亡，通过 Transwell 测定法测定对照、USP9X 缺陷型和 USP9X 缺陷型加过表达 MTH1 的 HGC-27 和 MKN-45 胃癌细胞的迁移和侵袭。
共免疫沉淀数据显示 USP9X 与 MTH1 相互作用并使其去泛素化。USP9X 的过表达通过下调其泛素化来升高 MTH1 蛋白水平，而 USP9X 的敲低对 MTH1 则有相反的作用。HGC-27 和 MKN-45 细胞中 USP9X 的缺乏导致增殖减少、细胞周期停滞、凋亡增加以及迁移和侵袭缺陷，而过表达 MTH1 可挽救这些缺陷。
USP9X 与 MTH1 相互作用并稳定其表达以促进胃癌细胞的增殖、存活、迁移和侵袭。
