YKL-40 in high-grade glioma: Prognostic value of protein versus mRNA expression

摘要

Background: YKL-40 has been reported to be associated with the prognosis of glioma patients. However, expression of YKL-40 was detected at protein or mRNA level in different studies. This may result in conclusion bias. This study is to investigate the prognostic value of increased YKL-40 protein versus mRNA expression in glioma patients. Methods: A comprehensive systematic search and review were performed using PubMed, EMBASE, and NKI databases to identify literature (published before May 1, 2018) that evaluated the association between YKL-40 and survival in glioma patients. Results: Thirteen relevant studies, involving 2139 patients, were included in this study. Elevated YKL-40 expression was associated with worse overall survival (OS) in glioma patients (hazard ratio [HR] = 1.44, 95% confidence interval [CI]: 1.27–1.63, P P = 0.008; glioblastoma multiform: HR = 1.52, 95% CI: 1.33–1.73, P P P = 0.001). However, the association between elevated YKL-40 mRNA level (detected by real-time PCR) with worse OS was not significant (HR = 1.44, 95% CI: 0.73–2.83, P = 0.29, I2 = 68.3%). In addition when status of IDH1 mutation or/and O6-methylguanine-DNA methyltransferase promoter was incorporated as multivariate, increased expression level of YKL-40 was not associated with poorer survival (HR = 1.39, 95% CI: 0.99–1.93, P = 0.055). Conclusion: YKL-40 protein level, rather than mRNA level, may be a valuable biomarker to assess the prognosis in glioma patients.