Wang Jaw-Yuan, Wang Yung-Hsin, Jao Shu-Wen, Lu Chien-Yu, Kuo Chao-Hung, Hu Huang-Ming, Hsieh Jan-Sing, Chong Inn-Wen, Cheng Tian-Lu, Lin Shiu-Ru
Department of Surgery, Faculty of Medicine, College of Medicine, and Kaohsiung Medical University Hospital, Kaohsiung Medical University, Taipei, Taiwan.
Oncol Rep. 2006 Dec;16(6):1245-52.
Mutations of K-ras gene have been demonstrated in 40-50% of colorectal cancer and large adenoma (>1 cm). This study was intended to clarify the correlation between the existence of K-ras oncogene and the pathological features of colorectal adenomas using our recently developed membrane arrays. Moreover, the downstream genes regulated by K-ras oncogene were explored to serve as potential biomarkers in the early diagnosis and risk assessment of patients with colorectal adenoma. Specimens were collected from 70 patients with colorectal adenoma. The alterations of K-ras oncogene were analyzed by direct sequencing and our constructed membrane arrays, respectively. The results of direct sequencing showed that 21 of 70 samples (30%) had K-ras gene mutations. The most frequently mutated sites included codons 12, 13, 15 and 18. Furthermore, activated K-ras oncogene was identified in 18 of 70 (25.7%) adenoma by membrane arrays. Statistical analyses showed that the membrane array had the accuracy of 90.0%, sensitivity of 88.9%, and specificity of 90.4%. The frequency of the mutational sites of K-ras gene was located as follows: codon 12, 100% (4/4); codon 13, 100% (4/4); codon 15, 75% (6/8); and codon 18, 100% (2/2). The analysis of the correlation between the experimental data and pathological characteristics of adenoma showed that activated K-ras oncogenes were significantly associated with the size, number and histology of adenomas (all P<0.001). Finally, we found the downstream genes activated by K-ras oncogene, including B-cell CLL/lymphoma 2 (BCL2), Homo sapiens H2A histone family, member Z (H2AFZ), Homo sapiens RAP1B, member of RAS oncogene family (RAP1B), Homo sapiens T-box 19 (TBX19), Homo sapiens E2F transcription factor 4, p107/p130-binding (E2F4) and matrix metallopeptidase 1 (MMP1), of which were overexpressed in most of all examined adenomas. These genes were then suggested to have functions involved in cell growth. The preliminary results indicated that the accuracy of membrane arrays was comparable to conventional DNA sequencing in the detection of activated K-ras oncogenes. Therefore, we propose that activated K-ras oncogene in colorectal adenomas may play an important role in the subsequent colorectal carcinogenesis through a group of K-ras-related molecular targets.
在40%-50%的结直肠癌和大腺瘤（>1 cm）中已证实存在K-ras基因突变。本研究旨在利用我们最近开发的膜阵列阐明K-ras癌基因的存在与结直肠腺瘤病理特征之间的相关性。此外，还探索了受K-ras癌基因调控的下游基因，以作为结直肠腺瘤患者早期诊断和风险评估的潜在生物标志物。收集了70例结直肠腺瘤患者的标本。分别通过直接测序和我们构建的膜阵列分析K-ras癌基因的改变。直接测序结果显示，70个样本中有21个（30%）存在K-ras基因突变。最常见的突变位点包括密码子12、13、15和18。此外，通过膜阵列在70个腺瘤中的18个（25.7%）中鉴定出激活的K-ras癌基因。统计分析表明，膜阵列的准确率为90.0%，灵敏度为88.9%，特异性为90.4%。K-ras基因的突变位点频率如下：密码子12，100%（4/4）；密码子13，100%（4/4）；密码子15，75%（6/8）；密码子18，100%（2/2）。腺瘤实验数据与病理特征的相关性分析表明，激活的K-ras癌基因与腺瘤的大小、数量和组织学显著相关（均P<0.001）。最后，我们发现了受K-ras癌基因激活的下游基因，包括B细胞淋巴瘤/白血病-2（BCL2）、人H2A组蛋白家族成员Z（H2AFZ）、人RAS癌基因家族成员RAP1B（RAP1B）、人T-box 19（TBX19）、人E2F转录因子4、p107/p130结合蛋白（E2F4）和基质金属蛋白酶1（MMP1），其中大多数在所有检测的腺瘤中均过度表达。这些基因被认为具有参与细胞生长的功能。初步结果表明，膜阵列在检测激活的K-ras癌基因方面的准确率与传统DNA测序相当。因此，我们认为结直肠腺瘤中激活的K-ras癌基因可能通过一组与K-ras相关的分子靶点在随后的结直肠癌发生中起重要作用。
