ɑ-硫辛酸“纠正”氧化应激微环境抑制慢性结肠炎恶性转化的机制研究

Effective interventions can be blocking chronic non-resolving inflammation mediates initiation and promotion of carcinogenesis. Our previous study shown that alpha LA inhibits tumor cell proliferation and clone formation and decreases the level of ROS. Transcriptome data reveal that some molecular associated with inflammatory signaling pathways, such as STAT3, IL-6, TNF-ɑ, are suppressed at level of transcription; Moreover, some ncRNAs that related to inflammation and tumorigenesis also significantly changed.This project will base on disease /colitis associated cancer animal models by alpha LA, using a variety of high-throughput methods to detected protection of chronic colitis of malignant transformation at different levels. Compare with dynamic change rules and regulation trends for chronic colitis of malignant transformation before and after the intervention by alpha LA. In addition, we will get outline for regulatory network that associated with oxidative stress microenvironment in non-resolving inflammation malignant transformation process. We expect to reveal that improve free radicals balance for cell/microenvironment restrain the process from chronic non-resolving inflammation to malignant transformation and to find key issue for this process by alpha LA treatment. These results will fully disclose a novel evidence by which alpha LA regulates microenviroment , and provide a theoretical basis for tumor prevention in future.

有效的干预手段可阻断慢性非可控性炎性向癌症发展的过程。课题组前期研究发现，α-LA能下调细胞内ROS水平并显著抑制肿瘤细胞增殖和克隆形成。对α-LA处理细胞转录组分析提示与炎症相关信号通路关键分子（STAT3、IL-6、TNF-α等）在转录水平被抑制；且与炎症及肿瘤发生相关的ncRNAs表达也出现显著改变。本项目将在α-LA干预的IBD/CRC动物模型基础上，利用多种高通量检测方法，从不同水平动态研究α-LA对慢性结肠炎恶性转化干预的作用。比较α-LA干预前后非可控性结肠炎恶性转化的变化规律及差异，勾勒出α-LA抑制的炎症恶性转化过程中对氧化应激微环境分子网络调节。希望借此揭示α-LA调节细胞/微环境中自由基平衡抑制非可控性炎症向肿瘤恶性转化的调控规律，寻找转化过程中的关键节点，为日后全面揭示α-LA改善细胞/肿瘤微环境及肿瘤预防提供理论依据。

恶性肿瘤是全球癌症相关死亡的主要原因。绝大多数肿瘤患者在确诊时已处于终末期，5年生存率仅维持在16%。ɑ-硫辛酸（Alpha lipoic acid，ɑ-LA）与其还原型二氢硫辛酸作为有效的天然抗氧化剂，可清除体内各种形式ROS，目前已被广泛用于与自由基代谢紊乱相关的慢性疾病的临床治疗中。也有一些报道称ɑ-LA对肿瘤细胞具有抑制作用，然而，ɑ-LA抑制肿瘤细胞增殖的具体机制目前仍不明确。.本研究我们首先采用RNA-Seq技术检测了ɑ-LA处理24h后HepG2细胞中出现的表达差异基因。结果显示，共有4,446个基因（2,097个基因表达下调，2,349个基因表达上调）的表达在ɑ-LA处理24h后呈现显著性改变。GO分析提示，编码肿瘤相关细胞膜蛋白的基因是受ɑ-LA影响最为显著的一类mRNA；蛋白质组学进一步提示Grb2可能是受ɑ-LA调控的膜受体信号通路中关键的靶分子。为了验证上述组学结果，接下来我们在A549、NCI-H1975及HepG2细胞中明确了ɑ-LA具有抑制肿瘤细胞增殖的作用，证实Grb2表达受ɑ-LA影响，并介导ɑ-LA诱导的细胞增殖抑制。ɑ-LA通过抑制细胞G1/S期的转换而抑制肿瘤细胞增殖；与细胞G1/S期的转换相关的调节蛋白CDK2/4/6,cyclinD3和E1的表达也随之发生了相应的改变。研究还发现ɑ-LA对EGFR突变的NSCLC细胞系中phospho-EGFR与phospho-ERK的抑制作用优于吉非替尼。进一步的实验证实ɑ-LA抑phospho-EGFR与phospho-ERK水平与Grb2表达下调相关联，ɑ-LA对Grb2的调节作用在一定程度抑制EGF诱导的EGFR相关通路活化。此外，我们还在公共样本数据库（GEO）肝脏恶性病变组织芯片中证实了EGFR与Grb2表达具有显著相关性。.综上所述，ɑ-LA抑制肿瘤细胞增殖是通过下调Grb2表达，抑制phospho-EGFR过度活化而实现，MAPK/ERK通路涉及其中。该研究为ɑ-LA用于临床肿瘤治疗提供了新的依据。