Table_2_Mutation Status and Immunohistochemical Correlation of KRAS, NRAS, and BRAF in 260 Chinese Colorectal and Gastric Cancers.DOCX

KRAS, NRAS and BRAF are kinases involved in the RAS-RAF-MAPK signaling pathway and also potential tumor-driven genes. Patients with KRAS/NRAS/BRAF mutations are resistant to anti-EGFR monoclonal antibody therapy. The main purpose of this study is to investigate the mutation status and distribution of KRAS/NRAS/BRAF in Chinese colorectal and gastric cancers, and to explore the histopathological changes and related immunohistochemical marker changes caused by these mutations. The mutation status of KRAS (exons 2, codon 12/13), NRAS (exons 2/3/4, codon 12/13/59/61/117/146) and BRAF (exons 15, codon 600) were detected by amplification refractory mutation system polymerase chain reaction (ARMS-PCR) in 86 colon cancer, 140 rectal cancer and 34 gastric cancer tissues. Then, the frequencies and distribution of KRAS/NRAS/BRAF mutations were described in detail. Furthermore, the relationship between KRAS/NRAS/BRAF mutations and the features of histopathological and related immunohistochemical markers were analyzed. The results showed that KRAS/NRAS/BRAF mutation rates in colon cancer were 44.2, 1.2, and 3.5%; in rectal cancer were 37.1, 4.3, and 0.7%; in gastric cancer were none, none and 2.9%. The mutation rate of KRAS in female (48.8%) is significantly higher than that of male (27.8%), and the mutation rate increased with the higher degree of differentiation. Additionally, the mutation rate of BRAF detected by ARMS-PCR (1.77%) was significantly lower than that by immunohistochemistry (4.11%). It also showed that the KRAS/NRAS/BRAF mutation status had a certain relationship with the expression of some immunohistochemical markers. This study provides more data support for clinical research on KRAS/NRAS/BRAF mutation in CRCs or gastric cancers.KRAS、NRAS与BRAF均为参与RAS-RAF-MAPK信号通路的激酶，同时也是潜在的肿瘤驱动基因。携带KRAS/NRAS/BRAF突变的患者对抗EGFR单克隆抗体治疗存在耐药性。本研究的主要目的为探究中国人群结直肠癌与胃癌组织中KRAS、NRAS、BRAF的突变状态及分布特征，并分析此类突变所引发的组织病理学变化与相关免疫组化标志物改变。本研究采用扩增阻滞突变系统聚合酶链反应（ARMS-PCR）检测86例结肠癌组织、140例直肠癌组织及34例胃癌组织中KRAS（第2外显子，密码子12/13）、NRAS（第2/3/4外显子，密码子12/13/59/61/117/146）及BRAF（第15外显子，密码子600）的突变状态；随后详细阐述了KRAS、NRAS、BRAF突变的发生频率与分布特征，并进一步分析了KRAS/NRAS/BRAF突变与组织病理学特征及相关免疫组化标志物之间的关联。结果显示，结肠癌组织中KRAS、NRAS、BRAF的突变率分别为44.2%、1.2%与3.5%；直肠癌组织中分别为37.1%、4.3%与0.7%；胃癌组织中KRAS与NRAS突变率均为0，BRAF突变率为2.9%。KRAS突变率在女性患者中为48.8%，显著高于男性患者的27.8%，且突变率随肿瘤分化程度升高而上升。此外，ARMS-PCR检测得到的BRAF突变率（1.77%）显著低于免疫组化检测结果（4.11%）。研究同时发现，KRAS/NRAS/BRAF的突变状态与部分免疫组化标志物的表达存在一定关联。本研究可为结直肠癌或胃癌的KRAS/NRAS/BRAF突变相关临床研究提供更多数据支撑。