FEN1 upregulation mediated by SUMO2 via antagonizing proteasomal degradation promotes hepatocellular carcinoma stemness

作者全名：Peng, Zhenxiang; Wang, Shuling; Wen, Diguang; Mei, Zhechuan; Zhang, Hao; Liao, Shengtao; Lv, Lin; Li, Chuanfei

作者地址：[Peng, Zhenxiang; Wang, Shuling; Wen, Diguang; Mei, Zhechuan; Zhang, Hao; Liao, Shengtao; Lv, Lin; Li, Chuanfei] Chongqing Med Univ, Affiliated Hosp 2, Dept Gastroenterol, Linjiang Rd, Chongqing 400010, Peoples R China

通信作者：Liao, ST; Lv, L; Li, CF (通讯作者)，Chongqing Med Univ, Affiliated Hosp 2, Dept Gastroenterol, Linjiang Rd, Chongqing 400010, Peoples R China.

来源：TRANSLATIONAL ONCOLOGY

ESI学科分类：CLINICAL MEDICINE

WOS号：WOS:001218288900001

JCR分区：Q1

影响因子：4.5

年份：2024

卷号：44

期号：　

开始页：　

结束页：　

文献类型：Article

关键词：Flap Endonuclease 1; Stemness; Hepatocellular carcinoma; Small ubiquitin-related modifier 2

摘要：Purpose: Metastasis of hepatocellular carcinoma (HCC) critically impacts the survival prognosis of patients, with the pivotal role of hepatocellular carcinoma stem cells in initiating invasive metastatic behaviors. The Flap Endonuclease 1 (FEN1) is delineated as a metallonuclease, quintessential for myriad cellular processes including DNA replication, DNA synthesis, DNA damage rectification, Okazaki fragment maturation, baseexcision repair, and the preservation of genomic stability. Furthermore, it has been recognized as an oncogene in a diverse range of malignancies. Our antecedent research has highlighted a pronounced overexpression of protein FEN1 in hepatocellular carcinoma, where it amplifies the invasiveness and metastatic potential of liver cancer cells. However, its precise role in liver cancer stem cells (LCSCs) remains an enigma and requires further investigation. Methods: To rigorously evaluate the stemness attributes of LCSCs, we employed sphere formation assays and flow cytometric evaluations. Both CD133+ and CD133- cell populations were discerningly isolated utilizing immunomagnetic bead separation techniques. The expression levels of pertinent genes were assayed via real-time quantitative PCR (RT-qPCR) and western blot analyses, while the expression profiles in hepatocellular carcinoma tissues were gauged using immunohistochemistry. Subsequent immunoprecipitation, in conjunction with mass spectrometry, ascertained the concurrent binding of proteins FEN1 and Small ubiquitin-related modifier 2 (SUMO2) in HCC cells. Lastly, the impact of SUMO2 on proteasomal degradation pathway of FEN1 was validated by supplementing MG132. Results: Our empirical findings substantiate that protein FEN1 is profusely expressed in spheroids and CD133+ cells. In vitro investigations demonstrate that the upregulation of protein FEN1 unequivocally augments the stemness of LCSCs. In a congruent in vivo context, elevation of FEN1 noticeably enhances the tumorigenic potential of LCSCs. Conversely, inhibiting protein FEN1 resulted in a marked reduction in LCSC stemness. From a mechanistic perspective, there exists a salient positive correlation between the protein expression of FEN1 and SUMO2 in liver cancer tissues. Furthermore, the level of SUMO2-mediated modification of FEN1 is pronouncedly elevated in LCSCs. Interestingly, SUMO2 has the ability to bind to FEN1, leading to a inhibition in the proteasomal degradation pathway of FEN1 and an enhancement in its protein expression. However, it is noteworthy that this interaction does not affect the mRNA level of FEN1. Conclusion: In summation, our research elucidates that protein FEN1 is an effector in augmenting the stemness of LCSCs. Consequently, strategic attenuation of protein FEN1 might proffer a pioneering approach for the efficacious elimination of LCSCs.

基金机构：National Natural Science Foundation of China [82103206]; General Project of Chongqing Natural Science Foundation [cstc2021jcyj-msxmX0018]; Special Support for Chongqing Postdoctoral Research Project [2021XM3027]; Kuanren Talents Program of the second affiliated hospital of Chongqing Medical University [kryc-yq-2224, 13- 003-023]; Senior Medical Talents Program of Chongqing for Young and Middle-Aged [11-020]; Chongqing medical scientific research project (Chongqing Health Commission) [2020GDRC014]; Chongqing medical scientific research project (Science and Technology Bureau) [2020GDRC014]

基金资助正文：This work was funded by the National Natural Science Foundation of China (Grant No.: 82103206), General Project of Chongqing Natural Science Foundation (Grant No.: cstc2021jcyj-msxmX0018), Special Support for Chongqing Postdoctoral Research Project (Grant No.: 2021XM3027), Kuanren Talents Program of the second affiliated hospital of Chongqing Medical University (Grant No.: kryc-yq-2224, 13- 003-023), Senior Medical Talents Program of Chongqing for Young and Middle-Aged (Grant No.: 11-020), Chongqing medical scientific research project (Joint project of Chongqing Health Commission and Science and Technology Bureau) (Grant No.: 2020GDRC014). No external funding was received in this study.