GDF15在口腔鳞癌TPF诱导化疗和调控AKT/ERK信号通路中的机制研究

Although induction chemotherapy agents could be used to treat malignancies by inducing the apoptosis of cancer cells, there are still debates on the clinical application of induction chemotherapy in oral squmaous cell carcinoma (OSCC). Growth differentiation factor 15 (GDF1) has been reported to be involved in the AKT/ERK pathways; however, the molecular role of GDF15 in cellular apoptosis is still unclear. Based on our previously established in vitro cellular carcinogenesis model of OSCC and genomic analysis, we found that GDF15 played an important role in progression of OSCC, it also correlated with the phosphorylation of AKT and ERK as well as cellular apoptosis; detection of GDF15 in biopsy samples from 256 OSCC patients in a clincial trial focusing on TPF induction chemotherpay shew that the patients with a low GDF15 expression had a significantly better survival, they also had a better response to TPF induction chemotherapy. However, in the literatures, there are few studies reporting the molecular mechanism of GDF15 expression on cellular apoptosis through AKT and ERK pathways, there are either few studies reporting the mechanism of treatment resistance in patients with GDF15 overexpression against TPF induction chemotherapy; so, there are still a lot of unknown mechanisms to be further investigated. Our present study will use the combination of basic machanism investigations and clincial trials to reveal the molecular mechanism of GDF15 on cellular apoptosis through AKT and ERK pathways and the molecular mechanism of treatment resistance of GDF15 overexpression against TPF induction chemotherapy in OSCC; a new clinical trial of GDF15 expression as a predictive biomarker for selecting TPF induction chemotherpay will also be designed and excuted based on the retrospective results of GDF15 anslysis in OSCC patients from the previous TPF trial. The aim of this study is to clarify the molecular mechanism of GDF15 in cellular apoptosis through AKT and ERK pathways, and a personalized treatment strategy based on predictive biomarker in patients with OSCC.

诱导化疗药物通过诱导癌细胞的凋亡发挥疗效，但在口腔鳞癌的临床应用中还存在争议。GDF15参与AKT/ERK信号通路，但在细胞凋亡中的机制尚不清楚。项目组在建立口腔黏膜上皮细胞体外癌变模型和基因组学研究的基础上，发现GDF15在口腔鳞癌发生发展中起重要作用，并且与AKT/ERK磷酸化和细胞凋亡相关；检测口腔鳞癌TPF诱导化疗临床试验的部分患者活检组织中GDF15表达，发现GDF15低表达的患者对TPF诱导化疗的有效率和预后，比GDF15高表达的患者好。本研究旨在结合分子机制研究和临床试验，围绕GDF15与AKT/ERK信号通路相关的细胞凋亡和GDF15抵抗TPF药物作用的分子机制，结合口腔鳞癌患者活检组织中GDF15表达作为预测性生物标志物选择TPF诱导化疗的临床试验，阐述GDF15在口腔鳞癌细胞凋亡中调控AKT/ERK信号通路的分子作用机制和作为预测性生物标志物的口腔鳞癌个体化治疗新策略。

本研究旨在阐述GDF15在口腔鳞癌细胞凋亡中调控AKT/ERK信号通路的分子作用机制和作为预测性生物标志物的口腔鳞癌个体化治疗新策略。.采用免疫共沉淀方法和质谱分析筛选GDF15结合蛋白，发现口腔鳞癌细胞中GDF15与erbB2形成复合体，促进了erbB2的磷酸化继而对下游AKT/ERK信号通路进行调控。过表达GDF15口腔鳞癌细胞通过caspase 依赖的细胞凋亡途径对TPF的敏感性增加,caspase 依赖的细胞凋亡途径中活化剪切的caspase-9、caspase-3 和 PARP 片段的表达水平上调。在干扰 GDF15 表达细胞中，细胞对化疗药物的敏感性降低，caspase 依赖的细胞凋亡途径活化减弱，细胞凋亡减少。裸鼠成瘤实验验证了过表达GDF15的口腔鳞癌在两周期的TPF化疗药物干预后较对照组更能控制肿瘤的进展，且具有统计学意义。.通过对随机临床试验患者GDF15表达的长期随访研究发现，临床T3/4N0M0 且高表达 GDF15 的口腔鳞癌患者能从TPF 诱导化疗中生存获益，包括总生存率（HR=0.238，P=0.009）、无病生存率（HR=0.300，P=0.009）、无局部复发生存率（HR=0.334，P=0.017）和无远处转移生存率（HR=0.231，P=0.007）。GDF15 表达可作为预测口腔鳞癌患者 TPF 诱导化疗疗效的潜在生物标志物，并设计和实施相应的II期临床试验加以验证（NCT02285530）。.通过Ion Torrent Personal Genome Machine对口腔鳞癌患者正常和肿瘤组织二代测序，发现GDF15 非同义突变是OSCC患者局部复发的危险因素(P=0.035），具有 GDF15 非同义突变的 OSCC 患者有更差的总生存期(P=0.073)和无病生存期（P=0.058）。与野生型GDF15患者相比，GDF15 错义突变的患者的预后较差，总生存率（P=0.035）， 无病生存率（P=0.032），无局部复发生存率（P=0.015）及无远处转移生存率（P=0.070）。GDF15 错义突变是局部晚期OSCC 患者总生存（P=0.003），无病生存(P=0.015)，无局部复发生存（P=0.008）及无远处转移生存（P=0.009）的独立危险因素。