活性氧参与肿瘤细胞凋亡调控的系统生物学研究及其靶向干预策略研究

Reactive oxygen species(ROS) is a critical transduction signal involved in the apoptosis induced by anticancer drugs. In the field of targeted cancer therapy, it is hot to learn how to regulate cellular ROS accumulation and to introduce apoptosis into tumor cells specifically. And it is popular to study molecular mechanisms underlying complicated signaling networks using systems biological tools. In our previous study, we have employed systems biology to investigate roles of ROS in the apoptosis induced by anticancer drugs,and found that ROS can significantly determine the activation of p38 MAPK which subsequently affect tumor cell apoptosis. In this issue, we will further investigate the key regulation network related with ROS-induced apoptosis, trying to explain how ROS can specifically introduce apoptosis into tumor cells, and to explore the key molecules involved in this network as well as the possible target intervention strategies. Based on these works, we will also investigate the role of ROS on tumor cells' drug sensitivity, and explain tumor cells' drug resistance which related with abnormal ROS regulation system. This research may improve our understanding about the mechanism underlying targeted killing effect of anticancer drugs, and provide theoretical bases for the exploration of new anticancer targets and therapies.

活性氧（ROS）是多种抗肿瘤药物诱导细胞凋亡的关键转导信号。如何专一性调控肿瘤细胞内ROS浓度，选择性诱导肿瘤细胞凋亡是当前抗癌靶向治疗研究的热点之一。通过系统生物学方法解决复杂的分子调控网络机制问题是当前生物学研究的新趋势。本课题前期研究采用系统生物学方法对ROS促肿瘤细胞选择性凋亡的可能分子机制进行了研究，发现ROS通过P38 MAPK途径直接影响了抗癌药物所诱导的细胞凋亡。本课题拟在此基础上，运用系统生物学方法，进一步研究ROS在抗癌药物选择性诱导肿瘤细胞凋亡过程中的作用及其所涉及的调控网络，阐明其凋亡调控机制，发现通路中的关键节点分子和潜在的靶向干预策略。并探讨ROS浓度调节异常对肿瘤细胞药物敏感性的影响，解释部分与活性氧调节异常相关的肿瘤耐药性问题。本研究可深化人们对抗癌药物作用机制的认识，也能为抗癌靶向治疗新靶点的发现和新型靶向药物的研发提供理论依据。

诱导细胞凋亡是靶向药物杀死癌细胞的主要方式，其诱导细胞凋亡的详尽分子机制尚不明确，极大的限制了新型靶向抗癌药物的设计和靶向药物获得性耐药等问题的解决。本项目对靶向药物敏感型肺癌细胞内活性氧（ROS）的浓度调控机制及其在靶向药物诱导的细胞凋亡中的作用进行了实验研究和理论分析。我们筛选出了对靶向药物gefitinib敏感的非小细胞肺癌（NSCLC）细胞系HCC827作为靶向抗癌实验研究材料，测试了肺癌细胞系中ROS的相对浓度，尝试了多种方式对细胞内的ROS浓度进行调控。添加过氧化氢模拟上调ROS实验研究表明，HCC827细胞为ROS敏感型细胞，上调ROS浓度会显著增加细胞的凋亡率。为下调细胞内ROS浓度，我们尝试了采用外加抗氧剂或siRNA干扰NOX2基因表达等方式。抗氧剂实验发现，外加抗氧剂不能发挥下调HCC827细胞内ROS浓度的作用，反而会诱发ROS浓度升高。siRNA干扰NOX2基因表达的研究发现，siRNA能有效抑制NOX2基因的转录，下调细胞内NOX2蛋白的浓度，从而显著下调细胞内ROS浓度水平。根据凋亡相关实验研究发现，gefitinib有显著的诱导NOX2基因表达，从而升高细胞内ROS浓度的作用，当使用siRNA抑制NOX2表达后，gefitinib诱导的细胞凋亡也受到了抑制。研究结果表明，gefitinib激发的细胞凋亡是严重依赖于其对NOX2基因的诱导表达作用的，ROS浓度调节在靶向药物的选择性杀伤作用中发挥了至关重要的作用。上述研究结果解释了部分与ROS浓度调节异常相关的肿瘤耐药性问题，深化了人们对靶向药物作用机制的认识，为抗癌靶向治疗新靶点的发现和新型靶向药物的研发提供了新的理论依据。