Expression And Clinical Significance Of TILs-related Factors And PD-L1 In DMMR/MSI-H Colorectal Cancer

Objective:To detect the expression of tumor infiltrating lymphocytes related factors(CD4,CD8,GATA3,TBX21)and PD-L1 in different MMR/MSI status colorectal cancers and compare the concordance of MMR protein expression with microsatellite status.To provide a new assessment perspective for the prognosis of dMMR/MSI-H colorectal cancer.Methods:1.TILs-related factors and PD-L1 expression in colorectal cancer and the relationship with prognosis were analyzed using Linked Omics database and Progno Scan database.2.We conducted a retrospective analysis of 1135 colorectal cancer cases diagnosed in Shanxi Cancer Hospital from June 2016 to December 2018.Among them,143 patients who were judged as dMMR were classified as the experimental group,and 272 cases who were judged as p MMR in the same period were randomly selected for the control study.3.The microsatellite status of 120 of these adequate cases of cancer tissue(including 50 dMMR-type and 70 p MMR-type colorectal cancers)was detected by multiplex fluorescence PCR-capillary electrophoresis and examined for concordance with their MMR protein expression profiles.4.The IHC method was used to examine the expression of TILs-related factors and PD-L1 in different MMR/MSI states,and to analyze the correlation between their expression levels and the pathological features of dMMR/MSI-H colorectal cancer and further analyze their prognosis.Results:1.Bioinformatics database analysis: Data from the Linked Omics database showed that the expression of CD4,CD8,TBX21,and PD-L1 correlated with the microsatellite status of CRC and was higher in the MSI-H group than in the MSS group(P<0.05).high CD4,CD8,GATA3,and TBX21 expression group had a longer overall survival than the low expression group in the Progno Scan database GSE17536 dataset(P<0.05).2.Clinicopathological features of dMMR/MSI-H colorectal cancer: The MMR protein was tested to be 97.5% consistent with MSI status(P<0.001).dMMR/MSI-H experimental group was more likely to be found in the right hemicolectomy and to have a deeper infiltration compared to the control group(P<0.001),and there were also differences in size and histological differentiation of tumor between the two groups(P<0.05).3.Expression of TILs-related factors and PD-L1 in colorectal cancer with different MMR protein status: Among the 415 fully enrolled cases,the expression of TBX21 and PD-L1 was remarkably higher in the dMMR experimental group than in the p MMR group(P<0.001),and the expression of CD8 was markedly differential between the two groups(P<0.05).4.Expression of TILs-related factors and PD-L1 in colorectal cancer with different MSI status: Among the 120 cases tested by PCR-MSI,the expression of TBX21 and PD-L1 was higher in the MSI-H group than in the MSI-L/MSS group(P values 0.009 and 0.017,respectively).5.Correlation of TBX21 and PD-L1 expression: TBX21 was statistically significantly and positively correlated with PD-L1 expression in dMMR/MSI-H colorectal cancer(r=0.422,P<0.01).6.Prognostic significance of TILs-related factors and PD-L1 expression profiles with dMMR/MSI-H colorectal cancer: The OS of dMMR/MSI-H colorectal patients was strongly correlated with lymph node metastasis,CD8,GATA3 and TBX21 expression(P<0.05).Patients in the TBX21-PD-L1-group had significantly shorter OS compared with the TBX21+PD-L1+ group(P=0.0042).TBX21 was shown to be an independent risk factor affecting the prognosis of dMMR/MSI-H colorectal cancer patients(P=0.028).Conclusion:1.The expression of TILs-related factors and PD-L1 was higher in dMMR/MSI-H colorectal cancer tissues than in p MMR control colorectal cancer,with the most significant differences in the expression of TBX21 and PD-L1,indicating a more active microenvironment in dMMR/MSI-H colorectal cancer tissues.2.TBX21 was significantly and positively correlated with PD-L1 expression.Patients with high TBX21 expression had longer overall survival.TBX21 is an independent risk factor affecting the prognosis of dMMR/MSI-H colorectal cancer patients and is expected to provide a new direction for the prognostic assessment of dMMR/MSI-H colorectal cancer.3.Detection of MMR protein by IHC staining and detection of microsatellite loci by multiplex fluorescence PCR-capillary electrophoresis,both of which have 97.5%agreement in detecting microsatellite status in colorectal cancer,can be carried out accordingly in clinical work according to the actual situation in the department.