TILRR (FREM1 isoform 2) is a prognostic biomarker correlated with immune infiltration in breast cancer

In atherosclerosis, upregulated TILRR (FREM1 isoform 2) expression increases immune cell infiltration. We hypothesized that TILRR expression is also correlated with cancer progression. By analyzing data from Oncomine and the Tumor Immune Estimation Resource, we found that TILRR mRNA expression was significantly lower in breast cancer tissue than adjacent normal tissue. Kaplan-Meier survival analysis and immunohistochemical staining revealed shortened overall survival and disease-free survival in patients with low TILRR expression. TILRR transcript expression was positively correlated with immune score, immune cell biomarkers and the expression of CXCL10 and CXCL11. TILRR expression was also positively correlated with CD8+ and CD4+ T-cell infiltration. These correlations were verified using the ESTIMATE algorithm, gene set enrichment analysis and Q-PCR. We concluded that impaired TILRR expression is correlated with breast cancer prognosis and immune cell infiltration.