肝转移相关蛋白IDH1 K224位点乙酰化通过HIF1α/SRC通路调控结直肠癌转移的作用机制研究

Hepatic metastasis is a key predictor for prognosis of patients with colorectal cancer (CRC). Nonhistone acetylation plays an important part in metastasis process of carcinoma. However, the key acetylated protein and critical acetylated site in CRC metastasis are still obscure. Our preliminary work using acetylated proteomics and site-directed mutation for amino acid showed that K224 of IDH1 was the key acetylated site for liver metastasis of CRC. IDH1 K224 might be regulated specifically by SIRT2 and affected HIF1α/SRC signaling pathway to regulate CRC metastasis. However, the key acetylated nonhistione, as well as the critical acetyalted sites are still obscure. In this study, we aims to investigate the relationship between IDH1 K224 acetylation and SIRT2, or HIF1α, or SRC expression, as well as the prognosis in CRC tissue samples, to demonstrate IDH1 K224 would be specifically deacetylated by SIRT2 and further influence CRC metastasis, to explore whether IDH1 K224 acetylation affects energy metabolism and oxidative stress in CRC cell lines, to investigate the mechanism by which IDH1 K224 acetylation regulates HIF1α/SRC pathway, and at last to verify the hyposis above using animal models. The research of IDH1 K224 acetylation associated pathways might throw a new light for treatment of liver metastasis in CRC.

肝转移是影响结直肠癌预后的重要因素，非组蛋白乙酰化在肿瘤转移中发挥重要作用，但结直肠癌肝转移关键的乙酰化非组蛋白和位点尚属未知。前期通过蛋白质乙酰化修饰组学等筛选出IDH1蛋白K224位点乙酰化可能在结肠癌肝转移中发挥关键作用；该位点可能受去乙酰化酶SIRT2特异性调节，并通过HIF1α/SRC通路调控结肠癌转移，但分子机制尚不清楚。本课题拟在人结直肠癌组织中探讨IDH1蛋白 K224位点乙酰化与SIRT2、HIF1α、SRC蛋白表达的相关性及与临床病理指标和预后关系；明确IDH1蛋白K224位点可被SIRT2特异性去乙酰化并调控结直肠癌侵袭转移；探索IDH1蛋白 K224位点乙酰化在催化活性、氧化应激和能量代谢中的作用；探索IDH1蛋白K224位点乙酰化调控HIF1α/SRC通路的分子机制；在裸鼠体内验证上述机制。IDH1蛋白K224位点乙酰化通路研究可能为结直肠癌肝转移治疗提供新靶点。

肝转移是影响结直肠癌预后的重要因素，非组蛋白乙酰化在肿瘤转移中发挥重要作用，但结直肠癌肝转移关键的乙酰化非组蛋白和位点尚属未知。我们课题组前期通过蛋白质乙酰化修饰组学等筛选出IDH1蛋白K224位点乙酰化可能在结肠癌肝转移中发挥关键作用；该位点可能受去乙酰化酶SIRT2特异性调节，并通过HIF1α/SRC通路调控结肠癌转移，但分子机制尚不清楚。本课题首先在人结直肠癌组织中探讨IDH1蛋白 K224位点乙酰化与SIRT2蛋白表达的相关性及与临床病理指标和预后关系，发现IDH1 蛋白 K224 位点乙酰化在结直肠癌肝转移灶中表达明显高于原发灶，IDH1 蛋白 K224 位点乙酰化水平与SIRT2 呈负相关，IDH1 蛋白 K224 位点乙酰化与结直肠癌患者临床病理指标及预后相关。IDH1 蛋白K224 位点被SIRT2 特异性去乙酰化并继而参与结直肠癌细胞侵袭转移调控。IDH1 蛋白 K224 位点乙酰化减弱IDH1 的催化活性；IDH1 蛋白K224位点乙酰化参与结肠癌细胞氧化应激反应和能量代谢过程。IDH1 蛋白K224 位点乙酰化通过调节转录因子HIF1α 羟基化及表达继而调控转移相关基因SRC 转录。最后裸鼠皮下成瘤及肝转移模型试验中，IDH1 K224R 组具有较低的转移发生率，并与HIF1α 和SRC 表达水平相关。IDH1蛋白K224位点乙酰化通路研究可能为结直肠癌肝转移治疗提供新靶点。