A Study On The Interplay Between Colorectal Cancer Cells And Its Surrounding Microenvironment

The tumor microenvironment(TME)is of vital importance for the incidence and development of colorectal cancer(CRC).Increasing evidence elaborated the vital role of TME in cancer subtype classification and patient prognosis,but a comprehensive understanding of CRC purely dependent on the stromal compartment is still lacking.To explore the role of immune context in cancer classification,we performed a gene expression microarray on the stromal compartment of colorectal cancer and its adjacent normal tissues.Integrated analysis with the public data GSE35602 identified four highly connected gene modules and classified patients into three immune subtypes:active immune,active stroma,and mixed type.These immune subtypes differed by the immune cell infiltration pattern,immune checkpoint expression level,mutation landscape,mutation burden and copy number burden,prognosis and chemotherapeutic sensitivity.Further analysis indicated that activation of the NF-kB pathway was the major mechanism causing the no immune infiltration milieu in the active stroma.Overall,these results suggest that characterizing colorectal cancer by the TME is of vital importance in predicting patients’ clinical outcomes and helping to guide precision and personalized treatment.The immune landscape of colorectal cancer(CRC)has been characterized.However,the diversity of epithelial cell,and the cooperation between cancer cell and the microenvironment cell to endow aggressive characteristics remain unclear.Here,we analyzed single-cell transcription data of 83,825 single cells from two public datasets including 29 tumors,6 tumor borders,16 adjacent normal tissues and validated the cellular survival influence in 864 samples including 220 tissue arrays and 644 colorectal cancer samples from The Cancer Genome Atlas.Diverse TME cellular clusters were identified,including T cell,B cell,plasma cell,myeloid cell and stromal cell.Distinct cellular composition was observed between tumors and adjacent normal tissues,and tumors exhibited immunosuppressive phenotypes including highly infiltrated with CD4 Tregs,IgG+plasma cell,tumor-associated macrophages(TAM)and cancer-associated fibroblast(CAF).For the epithelial cell,we implemented consensus nonnegative matrix factorization(cNMF)to each sample for the discovery of epithelial cell clusters.Seven epithelial cell clusters(C1-C7)with different biological functions and distinct invasive potential were identified.We found that C4 was the most invasive and correlated closely with the infiltration level of TAM and CAF.Interestingly,TAM and CAF associated with worse prognosis and dominated the epithelium-TME communication network.The association between TAM and C4 was validated using tissue arrays in vitro.Our study elaborates the cellular heterogeneity of colorectal cancer and provides in-depth insight into cancer cell heterogeneity,indicating the orchestrated roles among cancer cell,TAM and CAF,and potential new drug development from this sophisticated network.The spatial distribution of immune cell is of pivotal for the occurrence and development of colorectal cancer(CRC).Several studies have demonstrated the association between tumor infiltrated immune cells and CRC prognosis.However,few studies focused on the localized expression pattern of immune cells.In this study,we performed multiplex immunohistochemistry to assess the spatially expression pattern of 14 phenotypes related to T cell,B cell,myeloid cell and stromal cell in 190 CRC patients.The shortest distance between immune cell and cancer cell was calculated to investigate the spatial relationship between cancer cell and immune cell.Myeloid lineages including TAM and neutrophil had the shortest distance and the association between CD8T cell and overall survival was related with its distance to cancer cell.Unsupervised clustering identified 3 clusters with distinct immune cell infiltration pattern.One cluster C3 had the most favorable survival,was featured with T cell infiltration accompanied by B cell,indicating the nonnegligible role of humoral immunity.These results emphasize the importance of spatial locations of immune cell and support the finding that myeloid lineage was the closest immune population to cancer cell.