School of Basic Medical Sciences, Anhui Medical University, Hefei, China; Biopharmaceutical Institute, Anhui Medical University, Hefei, China.
School of Basic Medical Sciences, Anhui Medical University, Hefei, China; Biopharmaceutical Institute, Anhui Medical University, Hefei, China; Clinical college, Anhui Medical University, Hefei, China.
Biochim Biophys Acta Mol Cell Res. 2024 Jan;1871(1):119595. doi: 10.1016/j.bbamcr.2023.119595. Epub 2023 Sep 18.
The nuclear factor kappaB (NF-κB) subunit p65, plays an important role in the progression of hepatocellular carcinoma (HCC). Phosphorylation of p65 is considered as an important mechanism for the positive regulation of NF-κB activity. According to our previous data, p65 can be SUMOylated by small ubiquitin-related modifier 1 (SUMO1) protein, and SUMO1 promotes p65 nuclear import and HCC progression. However, the effect of SUMO1-related p65 SUMOylation on NF-κB transcriptional activity and the relationship between phosphorylation and SUMOylation of p65 remain obscure. Here, we found that phosphorylated p65 level was increased in cancer tissues of HCC patients, and similar phenomenon was found for SUMO1 expression but not for SUMO2/3. Further clinical data showed a positive correlation between SUMO1 and phosphorylated p65. We also verified that overexpression of SUMO1 upregulated phosphorylated p65 levels. Next, we verified SUMO1-related p65 SUMOylation with in vitro SUMOylation assay, constructed mutants of p65 SUMOylation and phosphorylation, and found that SUMO1-related p65 SUMOylation promoted p65 nuclear import and increased NF-κB activity. Both SUMO1-related p65 SUMOylation and p65 phosphorylation (especially at S276 site) increased the viability and invasion of hepatoma cells, and decreased the apoptosis of hepatoma cells. At last, we found that the phosphorylation of p65 promoted the level of SUMO1-related p65 SUMOylation, and SUMO1-related p65 SUMOylation upregulated phosphorylated p65 (at S276 site). Our study contributes to the exploration of the oncogenic mechanism of p65, which is the important protein in HCC.
核因子 kappaB (NF-κB) 亚单位 p65 在肝细胞癌 (HCC) 的进展中发挥重要作用。p65 的磷酸化被认为是 NF-κB 活性正向调节的重要机制。根据我们之前的数据，p65 可以被小泛素相关修饰物 1 (SUMO1) 蛋白 SUMO 化，SUMO1 促进 p65 核输入和 HCC 进展。然而，SUMO1 相关 p65 SUMO 化对 NF-κB 转录活性的影响以及 p65 磷酸化和 SUMO 化之间的关系仍不清楚。在这里，我们发现 HCC 患者癌组织中磷酸化 p65 水平增加，SUMO1 表达也出现类似现象，但 SUMO2/3 则不然。进一步的临床数据显示 SUMO1 与磷酸化 p65 呈正相关。我们还验证了过表达 SUMO1 上调磷酸化 p65 水平。接下来，我们通过体外 SUMOylation 测定、构建 p65 SUMOylation 和磷酸化突变体，验证了 SUMO1 相关的 p65 SUMO 化，发现 SUMO1 相关的 p65 SUMO 化促进 p65 核输入并增加 NF-κB 活性。SUMO1 相关的 p65 SUMO 化和 p65 磷酸化（特别是在 S276 位点）均增加肝癌细胞的活力和侵袭能力，减少肝癌细胞的凋亡。最后，我们发现 p65 的磷酸化促进了 SUMO1 相关的 p65 SUMO 化水平，SUMO1 相关的 p65 SUMO 化上调了磷酸化的 p65（在 S276 位点）。我们的研究有助于探索 p65 的致癌机制，p65 是 HCC 中的重要蛋白。
