Frequent detection of K-ras mutation in stool samples of colorectal carcinoma patients after improved DNA extraction: comparison with tissue samples.
Frequent detection of K-ras mutation in stool samples of colorectal carcinoma patients after improved DNA extraction: comparison with tissue samples.
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DOI：
10.3892/ijo.20.6.1263
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发表时间：
2002-06
影响因子：
5.2
通讯作者：
Yasushi Ito;Susumu Kobayashi;T. Taniguchi;O. Kainuma;T. Hara;T. Ochiai
中科院分区：
文献类型：
--
作者：
Yasushi Ito;Susumu Kobayashi;T. Taniguchi;O. Kainuma;T. Hara;T. Ochiai
粪便潜血检测广泛应用于结直肠肿瘤的临床筛查。然而，这种方法经常出现假阳性结果，因此应该建立更准确的筛查策略。尽管已经尝试利用粪便中的 K-ras 基因突变进行分子筛查以改善结果，但粪便中 DNA 提取率较低，使得该测量方法缺乏实用价值。在这项研究中，我们研究了我们所应用的粪便 DNA 提取方法是否可以产生足够的 DNA，用于通过粪便中 K-ras 基因突变对结直肠肿瘤进行分子筛查。我们应用十六烷基三甲基溴化铵 (CTAB) 溶液来改进从粪便中提取人类 DNA，并使用突变等位基因敏感扩增 (MASA) 方法来检测密码子 12 内的 K-ras 突变。我们能够通过识别所有 20 名患者的 K-ras 片段来确认粪便 DNA。 20 名患者中有 4 名（2 名癌症和 2 名腺瘤）发现组织 K-ras 突变。 6 名患者中发现粪便 K-ras 突变，其中 3 名组织 K-ras 突变阳性患者（2 名癌症和 1 名腺瘤）和 3 名组织 K-ras 突变阴性患者。这些结果表明，可以从所有结直肠肿瘤患者的人类粪便样本中提取足够的 DNA 用于 K-ras 突变研究。 K-ras 突变在粪便中比在切除的结直肠肿瘤中更常见。这项研究表明，粪便中K-ras突变筛查结直肠癌可能不仅包括原发性结直肠癌，还包括胃肠道各部位的癌前病变。
Fecal occult blood testing is widely used in the clinical screening of colorectal tumors. However, this method has so frequent false-positive results that more accurate screening-strategy should be established. Although the molecular screening using K-ras gene mutation in stools has been attempted to improve the results, the low rate of DNA extraction from stools leaves this measurement under utility value. In this study, we investigated whether or not our applied DNA extraction method from stools could produce enough DNA for the molecular screening of colorectal tumors by K-ras gene mutations in stools. We applied cetyltrimethylammonium bromide (CTAB) solution to improve human DNA extraction from stools and a mutant-allele-sensitive amplification (MASA) method to detect K-ras mutation within codon 12. We were able to confirm the stool DNA by identifying K-ras fragments in all the 20 patients. Tissue K-ras mutation was identified in 4 (2 cancers and 2 adenomas) of 20 patients. Stool K-ras mutations were found in 6 patients, 3 tissue K-ras mutation positive patients (2 cancers and an adenoma) and 3 tissue K-ras mutation negative patients. These results indicate that it is possible to extract enough DNA from human stool samples of all patients with colorectal tumors for K-ras mutation studies. K-ras mutations are more frequently detected in stools than in resected colorectal tumors. This study indicates that K-ras mutation screening in stools for colorectal cancer may include not only a primary colorectal cancer but also precancerous lesions in all parts of a gastrointestinal tract.