结直肠癌原发灶、门静脉血和肝转移灶K-ras基因突变的研究

Mutations of K-ras oncogene in primary colorectal tumors,related liver metastases and portal vein blood of patients with colorectal cancer

目的:观察结直肠癌患者门静脉血液、原发肿瘤组织及相应肝转移灶K-ras基因突变情况,分析三者的一致性,探讨结直肠癌患者门静脉血K-ras基因突变与肝转移关系。方法:实时荧光定量PCR技术和基因测序技术检测59例结直肠癌患者门静脉血液、原发肿瘤组织及15例肝转移灶K-ras基因突变,结合其临床资料分析。结果:59例结直肠癌组织中20例(33.9%)发现K-ras基因突变,18例(30.5%)结直肠癌患者的门静脉血中也发现K-ras基因突变,15例肝转移灶中8例(53.3%)发现K-ras基因突变,与原发癌组织的基因突变率差异不明显(P>0.05)。18例门静脉血存在K-ras基因突变者,其相应的肿瘤组织中均发现K-ras突变。结直肠癌组织中无K-ras基因突变者,患者门静脉血未发现基因突变。8例肝转移灶发现K-ras基因突变者门静脉血亦均有K-ras基因突变,7例肝转移灶无K-ras突变者门静脉血也无K-ras突变。原发肿瘤组织、相应门静脉血和5例同时性、2例异时性肝转移灶的K-ras基因突变类型基本一致(即K-ras基因12密码子GGT突变为GAT或GTT),1例异时性肝转移灶K-ras基因突变类型为13密码子GGC突变为GAC。原发癌组织与门静脉血K-ras基因突变一致率为96.6%(57/59),肝转移灶与门静脉血K-ras基因突变情况基本一致,但突变类型有不同。结论:结直肠癌的原发灶、门静脉血及肝转移灶的K-ras基因突变较为一致,原发癌组织和门静脉血均有K-ras基因的突变,预示着肿瘤可能通过血行转移至肝脏。

AIM:To evaluate the concordance of K-ras oncogene mutations in primary colorectal tumors,liver metastases and portal vein blood of the patients with colorectal cancer,and to find out the relationship between mutated K-ras oncogene and liver metastases in colorectal cancer.METHODS:Fifty-nine patients with colorectal cancer were screened for the mutations of K-ras oncogene in the tissue samples of primary tumors,portal vein blood and liver metastases(only 15 cases of the 59 patients)by real-time fluorescence quantitative PCR and DNA sequencing.The results were also analyzed with the clinical data of the patients.RESULTS:Point mutations of K-ras were found in the primary tumors in 20(33.9%)of the 59 patients with colorectal cancer,and 18(30.5%)of the 59 patients in their portal vein blood.K-ras mutations in 8(53.3%)of 15 liver metastases were also detected.No significant difference among the rates of K-ras mutation in primary tumor tissues,portal vein blood and related liver metastases was observed(P>0.05).Eighteen cases with mutated K-ras gene in portal vein blood showed the mutations in primary tumor tissues.The patients without mutated K-ras gene in primary tumor tissue also showed negative mutation of K-ras in the portal vein blood.The mutated K-ras gene in both liver metastase and portal vein blood were detected in 8 of the 15 cases with liver metastases,and no mutated K-ras gene was detected in the others with liver metastases.The main types of K-ras mutations found in primary tumors,liver metastases(5 simultaneous,2 metachronous)and portal vein blood were GGT to GAT and GGT to GTT at codon 12.A K-ras mutation at codon 13(GGC to GAC)was found in one case with metachronous liver metastases.The rate of concordance of K-ras status between primary tumors and portal vein blood was 96.6%.Detection of K-ras mutations in liver metastases was accordant with that in portal vein blood,but the type of K-ras mutation was partially discordant.CONCLUSION:The K-ras mutations in primary tumors,liver metastases and portal vein blood of patients with colorectal cancer are concordant,and mutated K-ras detected in both cancer tissue and portal vein blood may indicate liver micrometastases from colorectal cancer.