The expression of ERAP1 is favorable for the prognosis and immunotherapy in colorectal cancer: a study based on the bioinformatic and immunohistochemical analysis.

Abstract

Endoplasmic reticulum aminopeptidase 1 (ERAP1) is an emerging pharmacological target in cancer immunotherapy. This study was set out to examine the expression profiles and implications for prognosis and immunotherapy of ERAP1 in CRC. Based on bioinformatics and immunohistochemical analysis, we analyzed ERAP1 for potential diagnostic and prognostic significance in CRC. Functional enrichment analysis was conducted to detect the pathways associated with ERAP1, thus determining possible mechanisms. ESTIMATE, TIMER, and CIBESORT probed the links between ERAP1 and tumor-infiltrating immune cells. Lastly, we examined how ERAP1 expression correlated with the sensitivity to immunotherapy. Tumor tissues had decreased levels of ERAP1 expression relative to normal tissues. Patients whose ERAP1 expression was low suffered a worse chance of survival. Besides, it was shown that ERAP1 expression was associated with the advanced M stage and pathologic stage. Survival analysis revealed that low ERAP1 expression, age, pathologic stage, T stage, and M stage were independent indicators for unfavorable CRC patients' prognoses. The 1-, 3-, and 5-year OS calibration curves all fit well with the ideal model, suggesting that the age-ERAP1-T-stage-M-stage nomogram is a reliable predictor of OS. Additionally, we discovered that ERAP1 expression was associated with immune response and infiltration of various immune cells, such as down-regulated inhibitory immune cells and up-regulated stimulating immune cells. Sensitivity to PD-1 and CTLA4 inhibitors was associated with high ERAP1 levels. In summary, ERAP1 has potential as a diagnostic and prognostic biological marker, highlighting new insights into the study of CRC and the design of effective therapies.