p38γ介导的胆固醇代谢途径异常促进胰腺癌进展的机制及干预研究

致癌基因KRAS突变发生于90%以上的胰腺癌中，但靶向KRAS治疗胰腺癌尚未获得成功，开发其下游靶分子抑制剂是当前研究热点。我们前期研究发现KRAS重要下游分子p38γ在癌组织中表达升高且与病人不良预后相关。敲除p38γ可显著延长KPC胰腺癌转基因小鼠的生存期。RNA-seq分析发现KPC细胞中参与固醇合成的基因高度富集，Insig1和ABCA1表达降低。结合ATAC-seq分析发现p38γ敲除细胞Insig1和ABCA1的染色质开放增加，体外激酶实验结果表明p38γ可磷酸化Insig1。进而提出p38γ通过抑制Insig1和ABCA1转录及磷酸化Insig1促进SREBP2入核激活胆固醇合成的科学假设。本研究拟应用ChIP-Seq和质谱代谢组学等明确p38γ调控Insig1/ABCA1促进胰腺癌胆固醇合成的分子机制，应用p38γ特异性抑制剂吡非尼酮体内外验证其作为治疗靶点的可行性。

KRAS is mutated in 95% of PDACs and is a well-validated driver of PDAC growth and maintenance. However, despite comprehensive efforts, no effective anti-RAS drug has yet to reach the clinic. Strategies currently being pursued are taking an indirect approach by targeting proteins that facilitate RAS membrane association or downstream effector signaling. We found that elevated expression of p38γ, an important downstream target gene of RAS, is associated with tumor progression and poor prognosis in patients with pancreatic cancer. Most importantly, knockout of p38γ can significantly prolong the survival of KPC pancreatic cancer transgenic mice. RNA-seq analysis showed that genes involved in sterol biosynthesis were highly enriched in KPC cells. Combined with ATAC-seq analysis, we found that Insig1 and ABCA1 showed more open chromatin in p38γ knockout cells. In addition, p38γ knockout can significantly inhibit nuclear translocation of SREBP2. In vitro kinase experiment indicated that p38γ can phosphorylate Insig1. Thus, we hypothesize that p38γ activates SREBP2 regulated cholesterol synthesis by inhibiting transcription of Insig1 and ABCA1 and phosphorylating Insig1. Therefore, our study is aimed to investigate the underlying mechanisms of p38γ remodeling cholesterol metabolism of pancreatic cancer through the regulation of Insig1 and ABCA1 by ChIP and mass spectrometry based metabolomics et al. Besides, the anticancer activity of pirfenidone, a potent p38γ inhibitor, will be evaluated both in vitro and in vivo, to providing new insights on target therapy for pancreatic cancer.