摘要
目的探讨结直肠癌(CRC)患者MMR蛋白表达与微卫星不稳定(MSI)检测的一致性以及与临床病理特征的相关性,分析两种检测结果不一致的原因。方法选取392例CRC石蜡包埋组织(FFPE)样本,采用免疫组化(IHC)法检测4种MMR蛋白(MLH1、MSH2、MSH6及PMS2)表达,至少1种蛋白表达缺失判定为错配修复蛋白表达缺失(dMMR),全部阳性判定为错配修复蛋白表达完整(pMMR);采用PCR毛细管电泳法检测MSI,将至少2个单核苷酸重复位点发生改变,归纳为高度MSI(MSI-H);仅有1个单核苷酸重复位点发生改变,归纳为低度MSI(MSI-L);未发生改变,归纳为微卫星稳定(MSS)。结果392例CRC中,dMMR为18.9%(74/392),MSI-H占比18.1%(71/392)。IHC法检测的敏感度、特异性分别为97.2%和98.4%;PCR法检测结果的敏感度、特异性分别为93.2%和99.4%,两种检测方法的一致性为98.2%。7例检测结果不一致的样本中,2例PCR法检测结果为MSI-H,IHC法检测结果为pMMR;5例PCR法检测结果为MSS,IHC法检测结果为dMMR,其中2例MSH6蛋白单独缺失,3例肿瘤为黏液腺癌。dMMR组与pMMR组、MSI-H组与MSS/MSI-L组在发病年龄、肿瘤直径、肿瘤部位、组织类型、临床分期及淋巴结转移等方面比较,差异有统计学意义(P<0.05)。结论IHC法检测MMR蛋白与PCR法检测MSI具有较高的一致性。MSH6单独缺失时,PCR检测可能表现为MSS。肿瘤中含黏液时,肿瘤实际占比<50%可能对PCR检测有一定的影响。CRC中dMMR/MSI-H患者具有明显的临床病理特点,对临床病理诊断、治疗有一定的指导意义。
Objective To investigate the consistency of DNA mismatch repair proteins(MMR)protein and microsatellite instability(MSI)detection in colorectal cancers(CRC),and to analyze the differences between the two analyses.Methods Paraffin embedded tissue samples from 392 CRC were collected.Four MMR proteins(MLH1,MSH2,MSH6,and PMS2)were detected by using immunohistochemical(IHC)staining.MSI status was detected by using multiplex fluorescence polymerase chain reaction(PCR)-capillary electrophoresis.Absent expression of one or more of these MMR proteins in the tumor cells were classified as the MMR deficient(dMMR).Loss of expression in any of the four MMR proteins was defined as MMR proficient(pMMR).Changes in at least two mononucleotide sites can be summarized as high microsatellite instability(MSI-H).Change in one nucleotide site was classified as low microsatellite instability(MSI-L)and no change was classified as microsatellite stability(MSS).Results Among the analyzed 392 samples,18.9%(74/392)tumors showed dMMR,18.1%(71/392)tumors presented as MSI-H.The sensitivity and specificity were 97.2%and 98.4%for IHC testing,and were 93.2%and 99.4%for PCR analysis.The consistency of the two detection methods was 98.2%.Of the 7 tumors showed inconsistent results from the IHC and PCR analyses,2 cases were pMMR while MSI-H,5 cases were dMMR while MSS(2 cases showed loss of MSH6 protein expression,3 cases were mucinous adenocarcinoma).Patients with dMMR vs pMMR,or MSI-H vs MSS/MSI-L CRC displayed differences in age,tumor size,tumor location,histological type,clinical stage and lymph node metastasis(P<0.05).Conclusion Immunohistochemical detection of MMR protein was consistent with MSI-PCR detection.Loss of MSH6 expression alone may present as MSS.The PCR test may not accurate when the histopathological category is mucinous adenocarcinoma,because the actual tumor area covering may less than 50%.The dMMR/MSI-H CRC showed distinct clinicopathological characteristics,which could guide pathological diagnose and treatment strategies.
作者
孙林雍
王紫静
唐源
陈昶
江丹
Sun Linyong;Wang Zijing;Tang Yuan(West China Hospital of Sichuan University,Sichuan 610041,China)
出处
《医学研究杂志》
2021年第5期61-66,共6页
Journal of Medical Research
基金
四川省科技厅重点研发项目(2020YFS0237)。
关键词
结直肠肿瘤
MMR蛋白
微卫星不稳定性
Colorectal neoplasms
Mismatch repair protein
Microsatellite instability
