Analyses of infiltration patterns of immune cells in colorectal cancer and its correlation with clinical characteristics and overall survival of patients / 肿瘤研究与临床

ABSTRACT

ObjectvieTo investigate the infiltration patterns of immune cells in colorectal cancer, and to explore the correlation of immune cells infiltration with clinical characteristics and overall survival (OS) of patients.Methods:The RNA sequencing data of 615 patients with colorectal cancer were downloaded from The Cancer Genome Atlas (TCGA) database. The data was updated on July 19, 2019, and included 571 colorectal cancer tissues and 44 paracancerous tissues. There were 552 cases with clinical data, such as survival time, survival status, age, gender, clinical stage, grade, tumor location and so on. Using CIBERSORT deconvolution algorithm, the relative amounts of 22 immune cell types were calculated based on standardized gene expression data. According to the results of CIBERSORT algorithm, the samples with high accuracy of deconvolution result were selected ( P < 0.05), and they were used for analysis and graphing. The correlations between the infiltration patterns of immune cells and the clinical characteristics and OS of patients were analyzed. Results:After the CIBERSORT method was used to filter and remove samples with P ≥ 0.05, a total of 282 tumor tissue samples and 16 paracancerous tissue samples were screened. In 293 cases with clinical information, there were 277 tumor tissue samples and 16 paracancerous tissue samples. In 293 samples, M0 macrophages, M1 macrophages, M2 macrophages, CD8 + T cells and unactivated CD4 memory T cells accounted for a higher proportion of total immune cells; in tumor tissue samples, the expressions of M0 macrophages, M1 macrophages, activated CD4 memory T cells, and unactivated natural killer (NK) cells were higher; in paracancerous tissues, the expressions of naive B cells, M2 macrophages, activated NK cells, unactivated dendritic cells, unactivated mast cells and plasma cells were higher; with the increase of clinical stage, the expressions of follicular helper T cells, activated CD4 memory T cells, activated NK cells, M1 macrophages decreased, and the expressions of plasma cells and regulatory T cells increased, and the differences were statistically significant (all P < 0.05). M1 macrophages, unactivated mast cells, activated CD4 memory T cells, CD8 + T cells, and follicular helper T cells were highly expressed in right colon cancer, while M0 macrophages and activated mast cells were highly expressed in left colon and rectal cancer, and the differences were statistically significant (all P < 0.05). The patients were divided into high infiltration group and low infiltration group based on the median expression level of infiltrated immune cells, and the survival analysis was performed. The result of survival analysis showed that patients with high initial B cell infiltration had good OS; however, patients with high infiltration of M2 macrophages, activated mast cells, and neutrophils had poor OS. Conclusions:There are different types of immune cell infiltration patterns in the colorectal cancer samples of different stages and locations, which are closely related to tumor progression and OS of patients. They are expected to be applied to the development of therapeutic targets and prognosis prediction.