Exosome-related protein CRABP2 is upregulated in ovarian carcinoma and enhances cell proliferation.

Ovarian cancer is the most lethal cancer among women worldwide. Early diagnosis of ovarian cancer is a considerable challenge for gynecological oncologists. The exosome is a new emerging biomarker pool for cancer. Herein, we apply integrative transcriptome analysis to discover a new exosome biomarker for the diagnosis of ovarian carcinoma. We found 2316 differentially expressed genes (DEGs), among which were 431 DEGs that coded exosome proteins. We demonstrated three potential biomarkers-CRABP2, SPP1, and TNFAIP6, which are higher in ovarian cancer and associated with poor prognosis. According to receiver operating characteristic (ROC) curve analysis, CRABP2 performs better than the currently used biomarker CA125 in the diagnosis of ovarian cancer. CRABP2 level significantly elevates as the malignant property increases. We further confirmed that CRABP2 is upregulated in clinical tumor tissues of ovarian cancer patients as the malignant levels increase. CRABP2 can be detected and upregulated in the exosome in ovarian cancer patient serum samples rather than in healthy controls. GSEA revealed that high expression of CRABP2 was positively correlated with mitochondria oxidative phosphorylation pathway. At the same time, overexpression of CRABP2 can upregulate oxidative metabolism-related genes such as CYP4A11 and promote cell proliferation. Our findings based on CRABP2 could advance current practice in diagnosing and treating ovarian cancer.