The Study Of Expression Loss Of Mismatch Repair Gene And Corresponding Gene Mutation In Patients With Colorectal Cancer And Its Clinical Characteristics

Objective: In order to investigate the expression and mutation of mismatched repair gene(MMR)in colorectal cancer(CRC),and to analyze the correlation between MMR and the pathological and clinical characteristics of CRC,? Methods:the expression and mutation of four MMR proteins(MLHl,PMS2,MSH2 and MSH6)were detected by immunohistochemistry and LS gene detection respectively.All the expressions were classified as normal expression of MMR,and the lack of one or more MMR proteins was classified as MMR expression deficiency.All non-mutations were classified as MMR non-mutations,and one or more MMR gene mutations were classified as MMR mutations.Results:In 1415 CRC cases,the protein expression deletion rate was from high to low: PMS2 4.66%(66/1415),MLH1 2.47%(35/1415),MSH2 1.41%(20/1415),MSH6 1.06%(15/1415).The absence of MMR expression accounted for 6.50% of all CRC cases(92/1415).The common deletion rates of two or more proteins from high to low were :MLH1/ mms2 31.52%(29/92),MSH2/MSH6 6.52%(6/92),MSH2/PMS2 1.09%(1/92),MLH1/MSH2 1.09%(1/92),MLH1/MSH2/PMS2 1.09%(1/92),MLH1/MSH2/PMS2 1.09%(1/92),MLH1/MSH6/PMS2 1.09%(1/92),MLH1/MSH2/MSH6/PMS2 1.09%(1/92).The absence of MMR expression was more common in younger age,right hemicolon cancer,stage N0,0,stage I,and stage II groups than in normal MMR expression(P<0.05).The incidence of PMS2 and MLH1 deletions and MMR mutations was more common in stage T4 colorectal cancer(P<0.05).Among the 1415 CRC cases,the MMR expression deletion cases accounted for 2.97%(42/1415)of all CRC cases,and the MMR gene rate was from high to low: MLH1 1.48%(21/1415),MSH6 0.71%(10/1415),PMS2 0.64%(9/1415),MSH2 0.57%(8/1415).MMR gene mutations were more common in the T4 stage and ki-67 low-expression group than in the non-mmr group(P<0.05).Conclusion:1.The results of this study can further verify the previous research results,namely,MMR protein-deficient colorectal cancer has certain clinicopathological characteristics: the onset age is early,and it is more likely to occur in the right half of colon.2.The differences of PMS2,MLH1 and MMR mutations in the T4 stage were statistically significant,and further analysis may suggest that MMR protein and MMR mutations may play an important role in the occurrence and development of colorectal cancer,suggesting a poor prognosis.3.MMR gene germline mutation is negatively correlated with KI-67 expression,which may be a screening indicator for Lynch syndrome.4.In this study,the expression loss rate of MMR was 6.50%,and that of PMS2,MLH1,MSH2,and MSH6 was 4.66%,2.47%,1.41%,and 1.06%,respectively.5.In this study,the MMR gene germline mutation rate was 2.97%,and the gene mutation rates of MLH1,MSH6,PMS2 and MSH2 were 1.48%,0.71%,0.64% and 0.57%,respectively.