微卫星不稳定性与结直肠癌

Microsatellite instability and colorectal carcinoma

微卫星是基因组中广泛存在的重复碱基对组成的短DNA片段,容易发生插入或缺失突变。基因组中也存在DNA错配修复系统,其主要功能便是维持微卫星的稳定。当DNA错配修复系统缺陷时微卫星序列的长度会发生改变,称为微卫星不稳定性。Ⅱ期微卫星不稳定性肠癌患者预后较好,但不推荐含氟尿嘧啶的辅助化疗方案。免疫治疗能延长微卫星不稳定性转移性肠癌患者的生存期。但免疫治疗缺少有效的疗效预测指标.

Microsatellites are short segments of DNA composed of repeating base pairs and widespread in the genome,and are prone to insertion or deletion mutations. DNA mismatch repair systems also exist in the genome, whose main function is to maintain the stability of microsatellites.When DNA mismatch repair system defects, the length of microsatellite sequence will change, which is defined as microsatellite instability. Stage II colorectal cancer patients with microsatellite instsbility have a good prognosis, but fluorouracil containing adjuvant chemotherapy is not recommended. Immunotherapy can prolong the survival of patients with microsatellite unstable metastatic colorectal cancer. However, there is no effective index to predict the efficacy of immunotherapy.