乳酸/lincRNA-p21/PKM2正反馈环路促进TP53突变型口腔鳞癌恶性进展的机制研究

口腔鳞癌中高达80%患者存在TP53基因突变，突变导致侵袭性增强、有氧糖酵解活跃等恶性进展，而p53突变获能机制不明。前期文章发现：突变p53依赖NF-YA维持对lincRNA-p21的转录活性；NF-YA受干扰后，导致lincRNA-p21表达下调，难以结合阻断STAT3的激活。预实验发现：1）p53突变型患者糖酵解关键酶PKM2高表达；2）激活的STAT3能结合PKM2启动子区域，PKM2上调促进乳酸生成；3）乳酸刺激可下调E2F1和NF-YA表达。据此推测：乳酸通过E2F1抑制NF-YA表达，削弱突变p53对lincRNA-p21的转录活性，进而激活STAT3转录上调PKM2，促进有氧糖酵解及乳酸生成，形成正反馈环路增强恶性进展。项目将从细胞、分子和整体水平，利用ChIP、双荧光素酶、裸鼠成瘤等实验探讨此环路在TP53突变型口腔鳞癌中的功能，丰富p53突变获能机制，发掘代谢干预靶点。

TP53 gene mutated in up to 80% cases of head and neck squamous cell carcinoma (OSCC) and result in the enhancement of malignant progression including invasiveness and aerobic glycolysis. However, the underlying mechanism is still obscure. Our previous study found that the transcription of lincRNA-p21 regulated by the mutant p53/NF-YA complex. Interference of NF-YA expression repressed the activation of lincRNA-p21 and led to the loss of blocking effect on STAT3 phosphorylation. The preliminary experiments revealed that 1) PKM2, the key enzyme for glycolysis, was highly expressed in OSCC with mutant p53 gene; 2) phosphorylated STAT3 facilitated the production of lactate through binding the promoter region of PKM2 and up-regulating its expression; 3) E2F1 and NF-YA were suppressed under the stimulation of lactate. Based on these results, we speculate that lactate repress the expression of NY-YA through E2F1 to limit the formation of mutant p53/NF-YA complex and reduce the transcription of lincRNA-p21. The phosphorylation of STAT3 is highly expressed for the loss of lincRNA-p21 and facilitate PKM2 expression, result in an increasement of aerobic glycolysis and lactate production. This positive feedback loop promotes the malignant progression of OSCC. Our research will use a series of experiments including ChIP, luciferase and nude mice assays to explore the mechanism of this feedback loop in OSCC with mutant p53 gene in cell, molecular and organism levels, and aim to further understand the gain of function mechanism and identify metabolic intervention targets.