The Clinical Application Of Mismattched Repair Protein MLH1,MSH2,MSH6 And PMS2 In The Screening Of Lynch Syndrome-associated Colorectal Cancer In Tangshan

Objective The expression of four mismatch repair proteins(hMLH1?hMSH2?hMSH6and hPMS2)and the microsatellite instability in colorectal cancer were detected respectively by immunohistochemical and fluorescent PCR methods,and the relationship between them and clinicopathological features of colorectal cancer was discussed.The concordance of the two methods was analyzed and compared,and the feasibility of IHC method as a primary screening method for Lynch syndrome was evaluated.Methods EnVision immunohistochemical method was used to detect the expression of MMR proteins in 242 cases of CRC,and the relationship between the expression of mismatch repair proteins in CRC and the pathological features was analyzed.The microsatellite instability was detected by fluorescent PCR in 17cases(13 cases without MMR protein expression and 4 cases with MMR protein expression),and then analyzed the results consistency between the IHC and fluorescent PCR methods.Results The total deletion rate of mismatch repair protein expression was 14.04%,the total deletion rate of hMLH1 protein was 10.33%(25/242),hPMS2 protein deletion rate was 11.16%(27/242),hMLH2 protein deletion rate was 1.2%(3/242),the deletion rate of hMSH6 protein was 1.2%(3/242),the deletion rate of synchronous hMLH1 and hPMS2 ware 9.50%(23/242) and the deletion rate of synchronous hMSH2 and hMSH6 ware0.83%(2/242).Statistical analysis shows that in different gender groups,the deletion rate of hMLH1 was 5.37%(13/242) in male and 4.96%(12/242) in female.the deletion rate of hPMS2 was 5.79%(14/242) in male patients and 5.37%(13/242) in female patients,the deletion rate of hMSH2 or hMSH6 was 0.41%(1/242) in male patients,and the deletion rate of hMSH2 or hMSH6 was 0.83%(2/242)(P=0.450)in female patients.There was no significant difference between gender and MMR proteins deletion.The deletion rate of hMLH1 in patients under 65 years was 4.13%(10/242) and over 65 years old was 6.20%(15/242)(P=0.957) in different age groups.The deletion rate of hPMS2 was 3.71%(9/242) in patients over 65 years old,and 7.44%(18/242)(P=0.042)in patients under 65 years old.The deletion rate of hMSH2 or hMSH6 was 0.83%(2/242) in patients under 65 years old,and 0.41(1/242)(P=0.359) in patients over 65 years old.Statistical analysis shows that there was no significant difference between age and MMR proteins deletion.In different lymph node metastasis groups,hMLH1 deletion was 3.30%(8/242) in metastatic patients and 7.02%(17/242)(P=0.485)in non-metastatic patients.The deletions of hPMS2 were 3.30%(8/242) in metastatic patients,7.85%(19/242)(P=0.319) in non-metastatic patients.The deletions of hMSH2 or hMSH6 was 1.24%(3/242) in metastatic patients and0(P=0.056) in non-metastatic patients.Statistical analysis shows that there was no significant difference between lymph node metastasis and MMR proteins deletion.In the tumor size group,hMLH1 deletion was 0.83%(5/242) in patients with goiter size < 5cm and 8.26%(20/242) in patients with goiter size ? 5cm.The difference was significant(p=0.000),hPMS2 deletion was 2.48%(6/242) in patients with goiter size < 5cm and8.68%(21/242) in patients with goiter size ? 5cm(P=0.001).The deletions of hMSH2 and hMSH6 in patients with goiter size< 5cm were(0/242)and 1.24%(3/242)in patients with goiter size ? 5cm.There was no significant difference(P=0.098).In different differentiation groups,the deletion of hMLH1 was 0.21%(5/242) in the well-differentiated patients and 0.83%(20/242) in the patients with moderate and low differentiation,the difference was statistically significant(P=0.043).The deletion of hPMS2 was 0.21%(5/242)in well-differentiated patients and 9.10%(22/242) in poorly differentiated patients,the difference was statistically significant(P=0.034).The deletions of hMSH2,hMSH6 in highly differentiated patients was 0.41%(1/242) in the well-differentiated patients and0.83%(2/242) in the patients with moderate and low differentiation,there was no significant difference(P=0.740).In groups of different location,the deletion of hMLH1 was 0.21%(6/242) in the left hemicolon group and 0.83%(19/242) in the right halfcolon group,there was no significant difference between the two groups(P=0.058).The deletion of hPMS2 was 0.21%(6/242) in the left hemicolon and 9.10%(21/242) in the right hemicolon,the difference was statistically significant(P=0.034).The deletions of hMSH2,hMSH6 was 0.41%(1/242) in the left hemicolon and the right hemicolon was 0.83%(2/242)respectively,there was no significant difference between the two groups(P=0.623)17 cases(13 cases with MMR protein deletion and 4 cases without MMR protein deletion)were detected by fluorescent PCR,11 cases with mismatched repair protein deletion were MSI-H,2 cases was MSI-L,4 cases without MMR protein deletion were all MISS.The kappa method was used to test the consistency of the two methods,indicated a high degree of consistency(kappa =72.1%).MSI-H was correlated with location and differentiation degree(P=0.034),there was no significant difference between MSI-H and sex(P=0.307)?age(P=1.000)?size(P=0.057)?lymph node metastasis(P=0.600).Conclusions 1 The expression deletion of hMLH1 and hPMS2,hMSH2 and hMSH6 was synchronous,occurrence and the deletion of hMLH1,hPMS2 protein was more common.2hMLH1,hPMS2 protein expression loss was more common in the right side,poor differentiation and large tumor in CRC.3 The detection of mismatch repair protein deletion by immunohistochemical method was consistent with fluorescence PCR method for microsatellite instability,and the immunohistochemical method was cheap and easy to operate,so it could be used as a primary screening method for Lynch syndrome.Figure 5;Table7;Reference 66...