酶切富集联合DHPLC检测肿瘤患者外周血EGFR和KRAS基因突变及其临床应用

Objective To establish a REDE-DHPLC method for detecting the EGFR and KRAS mutations in plasma DNA from tumor patients, and investigate its clinical significance. Methods Restriction endonucleases Mse Ⅰ , Msc Ⅰ , BstN Ⅰ and Bgl Ⅰ were used to digest the wild type fragments of exon 19,exon 21 of EGFR gene and coden 12, 13 of KRAS gene for enriching the mutation fragments, and REDE-DHPLC method was established to detect EGFR and KRAS mutations. The sensitivities of REDE-DHPLC and conventional DHPLC were analyzed by using a series of plasmids containing 50%, 10%, 5%, 1% and 0. 1% mutation genes. Then, Plasma samples and paraffin-embedded tissue samples of 120 NSCLC patients and 120 colorectal cancer patients were detected by REDE-DHPLC. Compared with conventional DHPLC and sequencing, the diagnostic efficiency of REDE-DHPLC method was evaluated by detecting the mutation status of 2 genes in plasma of NSCLC and colorectal cancer patients. Results The sensitivity values of REDE-DHPLC and conventional DHPLC for detecting mutations in 4 loci were 0. 1% and 1%respectively. Plasmid DNA containing 0.1% mutation gene was detected to be positive continually for 2 to 3 times by REDE-DHPLC. EGFR mutation rates of 120 plasma from NSCLC patients detected by REDE-DHPLC, conventional DHPLC and sequencing methods were 27. 5%, 16. 7% and 12.5% respectively, and KRAS mutation rates of 120 plasma from colorectal cancer patients were 38. 3%, 25. 8% and 16. 7%,respectively. The positive rates of EGFR and KRAS mutation detected by REDE-DHPLC were significantly higher than conventional DHPLC(x2 = 4. 092, 4. 301, all P ＜ 0. 05 ) and sequencing method (x2= 8. 438,14. 127,all P ＜ 0. 05 ). In comparison with conventional DHPLC, the sensitivities of REDE-DHPLC for detecting EGFR and KRAS mutation were 100% (20/20,31/31), the specificities were 87. 0% (87/100)and 83. 2% (74/89). In comparison with sequencing method, the sensitivities of REDE-DHPLC were 100%( 15/15,20/20), the specificities were 82.9% (87/105)and 74. 0% (74/100). The coincidence rate of the two methods for detecting EGFR and KRAS mutation were 89. 2% ( 107/120, Kappa = 0. 690, P ＜ 0. 05 ) and 87.5% ( 105/120, Kappa= 0. 718, P ＜ 0. 05 ). The Consistency of EGFR and KRAS mutation status in plasma and tissues detected by REDE-DHPLC were 91.7% (33/36, Kappa =0. 939,P ＜0. 05)and 90. 2 %(46/51, Kappa = 0. 914, P ＜ 0. 05 ), respectively. Conclusions The REDE-DHPLC method is highly sensitive and specific for detecting EGFR and KRAS mutations in plasma DNA from tumor patients. The results are easy to be interpreted without missing homozygous point mutation, which indicate that the detection of EGFR and KRAS mutations in plasma DNA by REDE-DHPLC could therefore extend to be usedin clinical laboratory.

Detection and clinical significance of EGFR and KRAS mutation in peripheral blood from tumor patients by REDE-DHPLC