Laboratory of Research and Biosafety P3, Mohammed V Military Teaching Hospital, Faculty of Medicine and Pharmacy, Mohammed V University, Rabat, Morocco.
Laboratory of Human Pathologies Biology and Genomic Center of Human Pathologies, Department of Biology, Faculty of Sciences, Mohammed V University, Rabat, Morocco.
Asian Pac J Cancer Prev. 2022 Nov 1;23(11):3725-3733. doi: 10.31557/APJCP.2022.23.11.3725.
Mutations in RAS (KRAS, NRAS) and BRAF genes are the main biomarker predicting response to anti-EGFR monoclonal antibodies in targeted therapy in colorectal cancer (CRC).
Our study aims to evaluate the frequencies of KRAS, NRAS and BRAF mutations and their possible associations with clinico-pathological features in CRC patients from Morocco.
DNA was extracted from 80 FFPE samples using the QIAamp DNA FFPE-kit. RAS and BRAF mutations were assessed by pyrosequencing assays using Qiagen, KRAS Pyro®kit 24.V1, Ras-Extension Pyro®kit 24.V1 and BRAF Pyro®Kit 24.V1, respectively, and carried out in the PyroMark-Q24.
RAS mutations were identified in 57.5% (56.2% in KRAS, 8.8% in NRAS). In KRAS gene, exon 2 mutations accounted for 93.3% (68.9% in codon 12, 24.4% in codon 13). Within codon 12, G12D was the most prevalent mutation (37.7%), followed by G12C (13.4%), G12S (8.9%) and G12V (6.6%). Within codon 13, the most frequently observed mutation was G13D (22.3%). The mutation rates of exon 3 and 4 were 15.6% and 13.3%, respectively. In exon 3 codon 61, 2.3% patients were detected with two concurrent mutations (Q61R, Q61H), and 4.4% with three concurrent mutations (Q61R, Q61H, Q61L). In NRAS gene, the mutation rates of exon 2, 3 and 4 were 57.1%, 28.6%, and 14.3%, respectively. G13A and Q61H were the most common mutations, accounting for 42.9% and 28.5%, respectively. There were 13% patients with concurrent KRAS/NRAS mutation and 4.3% wt KRAS with NRAS mutations. No mutations were identified in BRAF gene. In both sexes, KRAS codon 12 mutations were associated with higher stage III/IV tumors. Moreover, Patients whose tumor is in the proximal colon (56.3%) are more likely to harbor KRAS mutations than those tumor located in rectum (25%).
RAS mutations could be useful in future target anti-EGFR therapy and molecular CRC screening strategy in Morocco.
RAS（KRAS、NRAS）和 BRAF 基因突变是预测结直肠癌（CRC）靶向治疗中抗 EGFR 单克隆抗体反应的主要生物标志物。
本研究旨在评估摩洛哥 CRC 患者中 RAS 和 BRAF 基因突变的频率及其与临床病理特征的可能关联。
使用 QIAamp DNA FFPE-kit 从 80 个 FFPE 样本中提取 DNA。使用 Qiagen 的 KRAS Pyro®kit 24.V1、Ras-Extension Pyro®kit 24.V1 和 BRAF Pyro®Kit 24.V1 分别通过焦磷酸测序检测 RAS 和 BRAF 基因突变，并在 PyroMark-Q24 中进行。
57.5%（KRAS 为 56.2%，NRAS 为 8.8%）发现 RAS 突变。KRAS 基因中，外显子 2 突变占 93.3%（密码子 12 为 68.9%，密码子 13 为 24.4%）。在密码子 12 中，G12D 是最常见的突变（37.7%），其次是 G12C（13.4%）、G12S（8.9%）和 G12V（6.6%）。在密码子 13 中，最常见的突变是 G13D（22.3%）。外显子 3 和 4 的突变率分别为 15.6%和 13.3%。在外显子 3 密码子 61 中，检测到 2.3%的患者同时存在两种突变（Q61R、Q61H），4.4%的患者同时存在三种突变（Q61R、Q61H、Q61L）。在 NRAS 基因中，外显子 2、3 和 4 的突变率分别为 57.1%、28.6%和 14.3%。G13A 和 Q61H 是最常见的突变，分别占 42.9%和 28.5%。有 13%的患者同时存在 KRAS/NRAS 突变，4.3%wt KRAS 存在 NRAS 突变。BRAF 基因未发现突变。在男性和女性中，KRAS 密码子 12 突变与较高的 III/IV 期肿瘤相关。此外，肿瘤位于近端结肠（56.3%）的患者比位于直肠（25%）的患者更有可能携带 KRAS 突变。
RAS 突变可用于摩洛哥未来的抗 EGFR 靶向治疗和分子 CRC 筛查策略。
