隐丹参酮下调USP1促Smad4泛素化降解阻断TGFβ诱导的胃癌转移侵袭的机制研究

Invasion and metastasis are the major difficulties in treating gastric cancer. TGFβ has been reported to be associated with the metastasis of gastric cancer. Recent research has also shown that Smad4 functioned as a critical mediator in TGFβ-induced metastasis of gastric cancer cells. Our preliminary data suggested that cryptotanshinon significantly reduced TGFβ-induced metastasis and invasion of gastric cancer cells and decreased the protein levels of Smad4 and ubiquitin-specific protease 1(USP1). In addition, silencing of USP1 by shRNA in gastric cancer cells showed a decreased expression of Smad4. Moreover, proteasome inhibitor MG132 can restore Smad4 expression in USP1-silenced gastric cancer cells. We then hypothesize that cryptotanshinon may block TGFβ-induced metastasis and invasion of human gastric cancer cells through inhibition of USP1-mediated deubiquitination of Smad4. We plan to apply technologies such as mouse models with gastric cancer xenografts and in situ proximity ligationassay to test this hypothesis.In our proposal, we aim to:(1) clarify the mechanism underlying how cryptotanshinon block TGFβ-induced metastasis of gastric cancer cells through Smad4 repression; (2) clarify the molecular mechanism underlying how cryptotanshinon promote ubiquitination and degradation of Smad4 through USP1 repression. Our research will not only lay the scientific foundation for the application of cryptotanshinon, the major bioactiveingredient oftraditional Chinese herb plant Salvia miltiorrhiza (Danshen), but also provide new direction for future studies on Chinese traditional medicine for cancer therapy.

抑制转移侵袭是胃癌治疗亟待解决的难题，且TGFβ高表达与胃癌高转移密切相关，Smad4是TGFβ/Smads信号通路诱导肿瘤转移的关键分子。我们前期研究发现，隐丹参酮显著抑制TGFβ诱导的胃癌细胞转移侵袭，并下调胃癌细胞Smad4的表达和去泛素化酶USP1的蛋白水平；USP1基因沉默后Smad4蛋白水平随之降低，该作用可被蛋白酶抑制剂逆转。基于此，我们提出隐丹参酮下调USP1促进Smad4泛素化降解进而阻断TGFβ诱导胃癌转移侵袭的科学假说。本项目拟通过胃癌裸鼠转移模型、原位邻近连接等技术：（1）明确隐丹参酮下调Smad4阻断TGFβ诱导的胃癌转移侵袭的作用效应；（2）揭示隐丹参酮下调USP1促Smad4泛素化降解的分子机制。通过本项目研究，不仅为中药丹参活性成分隐丹参酮的研发和临床应用提供科学依据，而且为中医药抗肿瘤治疗提供新思路。

抑制转移侵袭是胃癌治疗亟待解决的难题，且TGFβ高表达与胃癌高转移密切相关，Smad4是TGFβ/Smads信号通路诱导肿瘤转移的关键分子。本项目研究表明，隐丹参酮显著抑制TGFβ诱导的胃癌细胞转移侵袭，并下调胃癌细胞Smad4的表达和去泛素化酶USP1的蛋白水平；USP1基因沉默后Smad4蛋白水平随之降低，该作用可被蛋白酶抑制剂逆转。通过体内外实验，本项目揭示了隐丹参酮下调USP1促进Smad4泛素化降解进而阻断TGFβ诱导胃癌转移侵袭的作用机制。通过本项目的研究，为中药丹参活性成分隐丹参酮的研发和临床应用提供了科学依据，而且为中医药抗肿瘤治疗提供了新的思路。