AUTHOR=Yang Xi , Qi Quan , Pan Yuefen , Zhou Qing , Wu Yinhang , Zhuang Jing , Xu Jiamin , Pan Mingyue , Han Shuwen 

TITLE=Single-Cell Analysis Reveals Characterization of Infiltrating T Cells in Moderately Differentiated Colorectal Cancer

JOURNAL=Frontiers in Immunology

VOLUME=11

YEAR=2021

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2020.620196

DOI=10.3389/fimmu.2020.620196

ISSN=1664-3224

ABSTRACT=<sec><title>Objective</title><p>This study aimed to characterize the tumor-infiltrating T cells in moderately differentiated colorectal cancer.</p></sec><sec><title>Methods</title><p>Using single-cell RNA sequencing data of isolated 1632 T cells from tumor tissue and 1252 T cells from the peripheral blood of CRC patients, unsupervised clustering analysis was performed to identify functionally distinct T cell populations, followed by correlations and ligand-receptor interactions across cell types. Finally, differential analysis of the tumor-infiltrating T cells between colon cancer and rectal cancer were carried out.</p></sec><sec><title>Results</title><p>A total of eight distinct T cell populations were identified from tumor tissue. Tumor-Treg showed a strong correlation with Th17 cells. CD8<sup>+</sup>T<sub>RM</sub> was positively correlated with CD8<sup>+</sup>IEL. Seven distinct T cell populations were identified from peripheral blood. There was a strong correlation between CD4+T<sub>N</sub> and CD4+blood-T<sub>CM</sub>. Colon cancer and rectal cancer showed differences in the composition of tumor-infiltrating T cell populations. Tumor-infiltrating CD8<sup>+</sup>IEL cells were found in rectal cancer but not in colon cancer, while CD8<sup>+</sup> T<sub>N</sub> cells were found in the peripheral blood of colon cancer but not in that of rectal cancer. A larger number of tumor-infiltrating CD8<sup>+</sup> Tex (88.94%) cells were found in the colon cancer than in the rectal cancer (11.06%). The T cells of the colon and rectal cancers showed changes in gene expression pattern.</p></sec><sec><title>Conclusions</title><p>We characterized the T cell populations in the CRC tumor tissue and peripheral blood.</p></sec>