IGSF6 is a novel biomarker to evaluate immune infiltration in mismatch repair-proficient colorectal cancer.

Immunotherapy has dramatically changed the landscape of treatment for colorectal cancer (CRC), but currently lack of effective predictive biomarker, especially for tumors with mismatch repair (MMR) proficiency. The response of immunotherapy is associated with the cell-cell interactions in tumor microenvironment, encompassing processes such as cell-cell recognition, binding, and adhesion. However, the function of immunoglobulin superfamily (IGSF) genes in tumor immune microenvironment remains uncharacterized. This study quantified the immune landscape by leveraging a gene expression matrix from publicly accessible databases. The associations between IGSF6 gene expression and immune cell infiltration were assessed. The expression levels of IGSF6, CD8+ T cells, CD4+ T cells and CD68+ macrophage cells in cancer tissues from CRC patients and CRC cell lines were evaluated. IGSF6 was more highly expressed in CRC tumor tissues than adjacent normal tissues. And IGSF6 was significantly correlated with immune cell infiltration in MMR-proficient patients. Remarkably, MMR-proficient patients with high IGSF6 expression showed more sensitive to immunotherapy and chemotherapy than those with low IGSF6 expression. In summary, IGSF6 could be a novel biomarker to evaluate immune infiltration and predict therapeutic effect for MMR-proficient CRC.