AKT1与PIK3CA基因突变在KRAS突变型结直肠癌中作用及靶向干预的比较研究

PI3K/AKT pathway activation frequently occurs in concomitance with KRAS mutation in colorectal cancer (CRC), leading to poor prognosis. AKT1 mutations, same with PIK3CA mutations, can result in PI3K/AKT pathway activation. We previously detected the mutation profiling of 634 Chinese CRC patients by next-generation sequencing (NGS). The results showed that AKT1 mutations commonly coexisted with KRAS G13D mutations. We further found that AKT1 mutant patients with KRAS mutant metastatic CRC showed better overall survival as compared to PIK3CA mutant patients, suggesting that AKT1 and PIK3CA mutations may be not functionally equivalent in KRAS mutant CRC. However, the role of AKT1 mutation in KRAS mutant CRC remains elusive. In this work, in comparison with PIK3CA mutations, the clinicopathologic and molecular features of AKT1 mutations in a large cohort of KRAS mutant CRC patients are described. The role of AKT1 mutation in KRAS mutant CRC cell growth, apoptosis, invasion and metastasis is detected in vitro and in vivo, as compared to PIK3CA mutation. Moreover, the effects of PI3K/AKT and MEK inhibitor combinations on AKT1+KRAS mutant CRC cells are investigated. Our study aims to identify the role and clinical significance of AKT1 mutations in KRAS mutant CRC, and to explore the targeted intervention of AKT1 mutations in KRAS mutant CRC.

PI3K/AKT通路激活常发生在KRAS突变型结直肠癌 (colorectal cancer, CRC)中。除PIK3CA突变外，AKT1突变亦可激活PI3K/AKT通路。申请者前期利用NGS分析634例中国CRC患者突变谱发现，AKT1常与KRAS G13D共突变，在晚期KRAS突变型CRC患者中，AKT1突变组预后显著好于PIK3CA突变组。本研究拟在前期基础上，应用比较研究方法，通过比较大样本KRAS突变型CRC中AKT1和PIK3CA突变患者临床病理特征及预后差异，确定AKT1突变在KRAS突变型CRC中的临床意义。通过比较AKT1与PIK3CA突变对KRAS突变型CRC细胞增殖、凋亡和侵袭转移的影响，阐明AKT1突变在KRAS突变型CRC中的作用。通过检测PI3K/AKT+MEK双重抑制剂对AKT1+KRAS共突变细胞的作用，探索AKT1+KRAS共突变CRC患者的靶向治疗策略。

PIK3CA和AKT1突变在结直肠癌（CRC）的发生发展中起着重要作用，且常与KRAS突变同时出现，但两者在CRC中的特点及分子机制尚不清楚。本研究通过高通量二代测序技术对大样本中国CRC人群进行了基因变异检测，依据检测结果，我们明确了肿瘤细胞含量、化疗、肿瘤内异质性及原发灶/转移灶的异质性对分子检测结果准确性的影响，这部分的内容分别发表在SCI杂志《Cancer Letters》和中文核心期刊《肝癌电子杂志》上。在此基础上，我们初步阐明了PIK3CA突变、AKT1突变在中国结直肠癌人群，尤其是KRAS突变的结直肠癌中的突变特点、病理特征及靶向治疗预后的相关性，这部分内容发表在SCI杂志《Pathology-Research and Practice》上。另外，我们比较发现dMMR型CRC和pMMR型CRC的患者，其PIK3CA突变的发生率及克隆性存在较大的差异，PIK3CA突变在dMMR型CRC中突变率较高，且多为主克隆性突变，这部分内容发表在SCI杂志《Journal of Cancer》上。再者，我们通过体外实验，发现了AKT1突变和PIK3CA突变能够通过调控E-cadherin和Snail的表达促进肿瘤的侵袭，这部分的实验还在开展中。总之，通过本研究我们制定了CRC二代测序基因变异检测的质控标准，阐述了如何选择合适的CRC组织样本进行分子检测，明确了PIK3CA和AKT1突变在靶向治疗中的潜在作用，为CRC患者的精准诊治做出贡献和帮助。