BACKGROUND: B7H3 is an immuno-stimulatory glycoprotein that is overexpressed in cancer. However, its functional contributions to cancer development and progression are not well understood. In several reports, it was demonstrated that B7H3 reprograms lipid metabolism and regulates glucose metabolism. Isocitrate dehydrogenase 1 (IDH1), a metabolic enzyme in the TCA cycle, its reaction product is involved in lipid synthesis. Thus, we aimed to identify a novel marker to predict the prognosis of CRC patients and to investigate the relationship between IDH1 and B7H3.METHODS: We analyzed IDH1 and B7H3 expression levels in 225 CRC specimens by immunochemistry. Moreover, in vitro studies were performed to demonstrate the correlation between IDH1 and B7H3.RESULTS: Among 225 tissues, the positive rates of IDH1 and B7H3 were 37.8% (85/225) and 87.6% (197/225), respectively. In CRC samples, IDH1 significantly correlated with B7H3 expression (P = 0.044). Moreover, multivariate analyses revealed that high expression of both B7H3 and IDH1 and a high tumor grade were related to the prognosis of CRC patients. Kaplan-Meier survival analysis revealed that patients with co-expression of IDH1 and B7H3 had a poor overall survival. In SW480B7H3-EGFP cells, which highly express B7H3, IDH1 was up-regulated. Similarly, knockdown of B7H3 expression in Caco-2-shB7-H3 contributed to reduced IDH1 levels.CONCLUSIONS: Although IDH1 and B7H3 cannot be used as independent prognostic factors, co-expression of IDH1 and B7H3 significantly correlated with the prognosis of CRC patients and may serve as a combined predictive marker. Thus, the correlation between IDH1 and B7H3 has been proven in vivo and in vitro.
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