结直肠癌患者血清中CDKN2／p16基因异常的检测

 目的 寻找一种切实可行的检测肿瘤的生物标志物及其方法。方法 对100例结直肠癌患者取血清，另取献血员19例，非肿瘤患者13例为对照；并另取癌组织26份，癌旁组织22份及非恶性组织29份作对比观察，p16基因甲基化分析；并对其进行缺失分析及点突变的分析。结果 患者血清异常甲基化为69 %；缺失为9 %；点突变为45 %；癌组织之结果与血清相似；而癌旁组织显然较低。SSCP阳性者经序列分析证实有3例为错义突变，1例为移位，1例为同义突变。其中4例造成p16蛋白的缺失。作为肿瘤的生物标志物，3项联合应用其灵敏度为88 %，特异性为96.87 %，准确率为90.15 %。比文献用CEA+CA19-9+CA72-4+CA242 4项指标联合之灵敏度、特异性、准确率皆高。结论 血清DNA含量不高但能反映人体对肿瘤的负荷，本实验对DNA的质和量的要求不是太高，能检出10-3的DNA片段，可用于临床诊断及大面积普查，并可用于对出院患者的长期随访。并提示P16基因异常甲基化在结直肠癌癌变机制中起决定性作用。

Detection on aberrant CDKN2/p16 gene with serum DNA in colorectal cancer patients

Objective To research a biomarker and its relative technique to detect colorectal cancer.Methods The MSP,SSCP and deletion tests with serum were taken simultaneously in 100 cases of colorectal cancer patients and 2 groups of control,as well as the specimens of 26 cancer and 22 paraneoplastic tissue for contrast.Results The aberrant methylation rate of p16 in the serum was 69.00 %,deletion was 9.00 % and suspicious point mutation was 45.00 %.The data of cancer tissues is the same as that of the serum,but in paraneoplastic tissue is much lower.10 cases had been tested by sequencing analysis.Mutation types: 3 of missense;1 of frameshift;1 of nonsense.4 of them resulted in p16 protein defect.As a tumor marker,if combined using this 3 tests,it demonstrated the sensitivity of 88.00 %,specificity of 96.87 % and accuracy of 90.15 %.It is higher than the results of CEA,CA19-9,CA72-4,CA242 four markers' combination.If only examined the MSP and SSCP,the result was still higher than the former.Conclusion The content of DNA in serum is not too much,but it reflect the tumor burden of patient.MSP demands the quality or quantity of DNA is not too strict.The 10-3 fragments of DNA could be detected in the serum,it can be used in the clinical diagnosis or popular investigation,and long term postoperative follow-up.