MicroRNA-616对胃肠道肿瘤西妥昔单抗敏感性的影响及机制研究

Cetuximab is the most developed anti-EGFR monoclonal antibody. However, it’s not clear for the underlying molecular mechanisms of cetuximab sensitivity except K-RAS and N-RAS. Therefore, it’s necessary to explore the biomarkers of cetuximab. We previously identified that cetuximab has antineoplastic effects on gastric cancer. In addition, we found that the expression level of miR-616 is correlated with the efficacy of cetuximab. Further studies showed that, miR-616 was expressed in gastric cancer and clon cancer cell lines. The overexpression of miR-616 could inhibit the sensitivity of cetuximab, but had no impact on sensitivity of chemotherapeutic agents. PTEN and TP53BP2 are found to be potential targets of miR-616. Accordingly, we hypothesized that miR-616 is involved in the drug sensitivity of cetuximab in gastric cancer and colon cancer,and further explore the target genes of miR-616 and the underlying molecular mechanisms of regulation. We conduct our study at cell, tissue and clinical levels to confirm the hypothesis. This study will provide experimental basis to clarify the mechanisms of cetuximab sensitivity, help to screen the patients who will benefit from cetuximab and improve the prognosis of gastric cancer and clon cancer patients, which may have important theoretical significance and potential value.

西妥昔单抗（C225）是抗EGFR的单克隆抗体，目前除了RAS基因外，其他的分子标记物尚不明确。因此有必要寻找调控C225敏感性的因子。我们前期研究发现C225对胃癌有抗肿瘤作用，患者血浆miR-616表达水平与C225敏感性显著相关。进一步研究发现：胃癌和肠癌细胞中表达miR-616，其高表达抑制C225的敏感性，但对化疗药物的敏感性无影响，生物信息学筛选发现两个miR-616可能的下游靶基因：PTEN和TP53BP2。本课题拟在前期研究基础上，采用细胞实验结合临床治疗患者的样本检测研究miR-616表达水平改变对C225敏感性的影响，并通过其调控下游靶基因、EMT途径阐明机制；同时分析miR-616及其靶基因预测C225疗效的价值，筛选C225疗效预测因子。本研究的完成，有助于阐明C225敏感性调控机制，且对于筛选C225敏感患者、提高胃肠道肿瘤预后具有重要的理论意义和潜在应用价值。

西妥昔单抗（C225）是抗EGFR的单克隆抗体，目前除了RAS基因外，其他的分子标记物尚不明确。因此有必要寻找调控C225敏感性的因子。我们前期研究发现C225对胃癌有抗肿瘤作用，患者血浆miR-616表达水平与C225敏感性显著相关。通过本研究明确了miR-616与胃肠道肿瘤细胞的恶性生物学行为有关：可促进细胞增殖、迁移、侵袭、促进细胞发生上皮间质转化；明确了miR-616可降低胃肠道肿瘤细胞对西妥昔单抗的药物敏感性；通过筛选及验证明确了PTEN为miR-616的下游靶基因。miR-616可能通过抑制PTEN表达，激活pAKT通路引起肿瘤细胞对西妥昔单抗耐药。而上调PTEN后，可明显逆转miR-616上调所致的PTEN通路抑制和EMT通路相关分子的激活。体内研究显示miR-616表达水平上调后，裸鼠的肺转移明显增多，血浆VEGFR2表达水平明显升高。本研究的完成，有助于阐明C225敏感性调控机制，且对于筛选C225敏感患者、提高胃肠道肿瘤预后具有重要的理论意义和潜在应用价值。