Expression Of Interferon Regulatory Factor 3 In Colon Cancer And Its Regulatory Effect On Colon Cancer Growth

Research backgroundColon cancer is a common malignant tumor of digestive tract,and its morbidity and mortality are still increasing.According to the statistics published by the National Cancer Center of China in 2015,the incidence and mortality of colon cancer in China are among the top 5 among all malignant tumors,which has become one of the serious threats to the health of our residents.Clinical studies have shown that the occurrence and development of colon cancer are related to mutations in many genes.Clinical studies have shown that the occurrence and development of colon cancer involves many genes,among which the mutation rate of APC(adenomatous polyposis coli,APC)gene can reach 85%,and its mutation can lead to the occurrence and development of colorectal adenoma.Most colorectal cancer originates from the formation and development of colorectal adenoma.Interferon regulatory factor 3(IRF3)is one of the important members of the interferon regulatory factor family and has many biological functions such as immunomodulation,antiviral,anti-inflammatory and anti-tumor.One study on interferon regulatory factors and the incidence of colon and rectal cancer noted that five single-nucleotide polymor-phism(SNP)in IFNγ、IRF2 and IRF3 of these three genes were associated with the incidence of colon cancer and indicated that the risk of IRF3 increased most.Moreover,in recent years,people have detected high expression of IRF3 in many kinds of cancers,and began to pay attention to the related effects of IRF3 gene changes.Such as IRF3 deletion can lead to increased incidence of corneal infection herpes simplex virus type 1(HSV-1),decreased retinal thickness and damage to the integrity of retinal synapses,but these studies mainly focus on inflammation and immunomodulation.There are few reports on IRF3 and cancer development and prognosis,therefore,this paper revolves around the occurrence and development of IRF3 and colon cancer and its related mechanisms.Methods1.The expression of IRF3 and p-IRF3 in human colon cancer and adjacent tissues was detected by immunohistochemical method.The product of’staining intensity score’ and’staining positive rate’ was used as the total score of immunohistochemistry,and then the expression difference of IRF3 and p-IRF3 was analyzed quantitatively2.We grouped 75 clinical cases from 8 aspects,including age,sex,pathological grade,maximum tumor diameter,T stage,N stage,M stage and TNM stage.Immunocytochemistry was used to detect those cases,and then the correlation between IRF3 and p-IRF3 expression levels and clinicopathology of colon cancer patients was analyzed.3.To analyze the correlation between IRF3 expression level and survival rate of colon cancer patients.We selected 597 cases from the TCGA database and divided into two groups according to the IRF3 expression level,including 286 cases of high expression,311 cases of low IRF3 expression,and the Kaplan-Meier curve was used to analyze the IRF3 expression level and survival rate of colon cancer patients.4.APCMin+IRF3+/-mouse model was established.An APCMin/+IRF3+/-mouse model of offspring with double gene defects was obtained by breeding.The specific breeding methods are as follows:male APCMin/+mice were used to mate with female IRF3-/-mice,the whole DNA of tail tip was extracted from offspring mice by tail clipping,target gene sequences were amplified by qPCR,then screen out the offspring APCMin/+IRF3+/-mice5.To analyze the effect of IRF3 gene deficiency on intestinal tumor growth in APCMin/+mice.We established APC gene mutation induced intestinal tumors in mice and analyzed the number and size of intestinal tumors in APCMin/+mice with IRF3 gene deficiency by H.E.staining.6.To analyze the mechanism of the inhibition effect of IRF3 gene deficiency on intestinal tumor growth in APCMin/+mice.The expression levels of IRF3 and p-IRF3 proteins in tumor were detected by Western blot,and the expression levels of apoptosis-related genes Bax、Bcl-2、p-p38 MAPK and c-Myc were detected by immunohistochemistryResults1.The expression level of IRF3 in cancer tissues was higher than that of corresponding adjacent tissues,and its expression level was related to pathological grade and maximum tumor diameter in colon cancer patients,but there was no significant correlation with patient’s age,sex,T stage,pathological type,N stage,M stage and TNM stage.2.p-IRF3 is found in cytoplasm and nucleus,and the expression level in cancer tissues is higher than that in adjacent tissues.The expression level of p-IRF3 in the cytoplasm was only closely related to the patient’s pathological grade,and there was no significant correlation with the patient’s age,sex,maximum tumor diameter,T stage,pathological type,N stage,M stage and TNM stage.The expression of p-IRF3 in the nucleus was related to patient’s age,sex and pathological grade,but not to the maximum diameter of tumor,T stage,pathological type,N stage,M stage and TNM stage.3.IRF3 and p-IRF3 were highly expressed in grade II and significantly higher than those in grade I and III in pathological grades.4.The statistical results of 597 cases selected from the TCGA database showed that the survival rate of patients with IRF3 low expression was higher than that of patients with high expression.5.IRF3 gene deficiency can inhibit the occurrence and development of intestinal adenoma in APCMin/+mice by reducing the number and size of intestinal adenomas.6.IRF3 gene deficiency reduces IRF3 and p-IRF3 protein expression levels in APCMin/+mice.7.IRF3 gene deficiency promotes apoptosis in intestinal adenomas in APCMin/+mice 8.IRF3 gene defects promote the activation of p38MAPK/c-Myc signaling pathways.ConclusionsIRF3 expression level in human colon cancer tissues is higher than that in corresponding adjacent tissues and is closely related to the pathological grade and maximum tumor diameter of patients.The expression level of p-IRF3 in colon cancer tissues was higher than that in corresponding adjacent tissues,the p-IRF3 in cytoplasm was only related to the pathological grades of patients,and the p-IRF3 in nucleus was related to the pathological grades,age and sex of patients.The expression levels of IRF3 and p-IRF3 in grade II were significantly higher than those in grade I and III in pathological grade.IRF3 gene deletion can reduce the number and size of intestinal tumors and alleviate the occurrence and development of intestinal adenomas in mice colorectal cancer models induced by APC gene mutation.The mechanism may be related to the decreased expression of IRF3 and p-IRF3,the increased proportion of Bax/Bcl-2 and the activation of p38 MAPK/c-Myc signaling pathwayInnovationsThis research mainly has the following two innovations:the first,we preliminarily determined that IRF3 has oncogene characteristics and is a positive regulator of colon cancer growth;the second,the expression level of IRF3 was closely related to the pathological grade of colon tumor and IRF3 gene deficiency could inhibit the growth of intestinal tumors in the background of APC gene mutation.