胰腺癌干细胞（CSCs）促进胰导管腺癌（PDAC）的肿瘤发生和耐药性。细胞周期依赖性激酶1（CDK1）在其他肿瘤中在肿瘤发生中起重要作用，但CDK1在PDAC中的功能尚不清楚。花青素是一种具有抗肿瘤特性的活性黄酮类化合物，然而其在CSCs中的功能尚不明确。本研究证明了CDK1与预后相关，在胰腺癌组织和吉西他滨耐药细胞中高表达。沉默CDK1会削弱肿瘤干性和减少CSCs的亚群表达。我们发现花青素通过阻断CDK1的激酶结构域来抑制胰腺CSCs的特性。通过乙酰化蛋白质组学分析和磷酸化阵列分析，我们证实花青素降低了CDK1的表达，并增加了CDK1在赖氨酸33（K33）上的乙酰化，从而抑制了CDK1的磷酸化。沉默CDK1或STAT3能抑制肿瘤干性特性，而过表达CDK1或STAT3则产生相反的效果。CDK1在K33的突变或乙酰化会减弱STAT3在Y705的磷酸化，从而损害干细胞相关基因的表达和胰腺癌干性。此外，缺乏组蛋白去乙酰化酶3（HDAC3），它可以去乙酰化CDK1，通过调节CDK1的翻译后修饰来调节STAT3的磷酸化，从而降低PDAC的干细胞特性。此外，我们的结果表明，花青素通过抑制CDK1-STAT3轴，通过体外和体内消除胰腺CSCs的亚群，增强了吉西他滨的效果。我们的发现突显了CDK1-STAT3信号翻译后修饰在维持PDAC的癌干性中的作用，并提示以花青素等抑制剂靶向CDK1-STAT3轴是减少耐药性和消除PDAC的潜在治疗策略。© 2023. 美国华人生物科学家协会（SCBA）。

Pancreatic cancer stem cells (CSCs) promote pancreatic ductal adenocarcinoma (PDAC) tumorigenesis and chemoresistance. Cyclin-dependent kinase 1 (CDK1) plays an important role in tumor initiation in other tumors, but the function of CDK1 in PDAC remains unclear. Fisetin is a bioactive flavonoid with anti-tumor properties in multiple tumors, while its function in CSCs remains elusive.In this study, we demonstrated that CDK1 was correlated with prognosis and was highly expressed in pancreatic cancer tissue and gemcitabine-resistant cells. Silencing CDK1 impaired tumor stemness and reduced a subset of CSCs. We found that fisetin blocked the kinase pocket domain of CDK1 and inhibited pancreatic CSC characteristics. Using acetylation proteomics analysis and phosphorylation array assay, we confirmed that fisetin reduced CDK1 expression and increased CDK1 acetylation at lysine 33 (K33), which resulted in the suppression of CDK1 phosphorylation. Silencing CDK1 or STAT3 suppressed tumor stemness properties, while overexpressing CDK1 or STAT3 showed the opposite effect. Mutation or acetylation of CDK1 at K33 weakened STAT3 phosphorylation at Y705, impairing the expression of stem-related genes and pancreatic cancer stemness. In addition, lack of histone deacetylase 3 (HDAC3), which deacetylates CDK1, contributed to weakening STAT3 phosphorylation by regulating the post-translational modification of CDK1, thereby decreasing the stemness of PDAC. Moreover, our results revealed that fisetin enhanced the effect of gemcitabine through eliminating a subpopulation of pancreatic CSCs by inhibiting the CDK1-STAT3 axis in vitro and in vivo.Our findings highlight the role of post-translational modifications of CDK1-STAT3 signaling in maintaining cancer stemness of PDAC, and indicated that targeting the CDK1-STAT3 axis with inhibitors such as fisetin is a potential therapeutic strategy to diminish drug resistance and eliminate PDAC.© 2023. Society of Chinese Bioscientists in America (SCBA).