Circulating Methylated XAF1 DNA Indicates Poor Prognosis for Gastric Cancer |
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| Authors: | Zhi-Qiang Ling Ping Lv Xiao-Xiao Lu Jiang-Liu Yu Jing Han Li-Sha Ying Xin Zhu Wang-Yu Zhu Xian-Hua Fang Shi Wang Yi-Chen Wu |
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| Affiliation: | 1. Zhejiang Cancer Research Institute, Zhejiang Province Cancer Hospital, Zhejiang Cancer Center, Hangzhou, Zhejiang, China.; 2. Department of Pathology, Zhejiang Province Cancer Hospital, Zhejiang Cancer Center, Hangzhou, Zhejiang, China.; 3. Department of Endoscopy, Zhejiang Province Cancer Hospital, Zhejiang Cancer Center, Hangzhou, Zhejiang, China.; Vanderbilt University Medical Center, United States of America, |
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| Abstract: | BackgroundMethylated DNA in fluids may be a suitable biomarker for cancer patients. XAF1 has been shown to be frequently down-regulated in human gastric cancer (GC). Here, we investigated if XAF1 methylation in GC could be a useful biomarker.MethodsReal-time RT-PCR was used to detect XAF1 mRNA expression; immunohistochemistry and western blot were used to examine XAF1 protein expression in GC tissues (n = 202) and their corresponding para-cancerous histological normal tissues (PCHNTs). Real-time methylation specific-PCR was used to investigate XAF1 promoter methylation in the same panel of GC tissues, their PCHNTs and sera.ResultsWe confirmed frequent XAF1 down-regulation in both mRNA and protein levels in GC tissues as compared to normal controls and PCHNTs. XAF1 hypermethylation was evidenced in 83.2% (168/202) of GC tissues and 27.2% (55/202) of PCHNTs, while no methylation was detected in the 88 normal controls. The methylation level in GC tissues was significantly higher than that in PCHNTs (p<0.05). The hypermethylation of XAF1 significantly correlated with the down-regulation of XAF1 in GC tissues in both mRNA and protein levels (p<0.001 each). Moreover, we detected high frequency of XAF1 methylation (69.8%, 141 out of 202) in the sera DNAs from the same patients, while the sera DNAs from 88 non-tumor controls were negative for XAF1 methylation. The XAF1 methylation in both GC tissues and in the sera could be a good biomarker for diagnosis of GC (AUC = 0.85 for tissue and AUC = 0.91 for sera) and significantly correlated with poorer prognosis (p<0.001). In addition, after-surgery negative-to-positive transition of XAF1 methylation in sera strongly associated with tumor recurrence.Conclusions1) Dysfunction of XAF1 is frequent and is regulated through XAF1 promoter hypermethylation; 2) Detection of circulating methylated XAF1 DNAs in the serum may be a useful biomarker in diagnosis, evaluating patient’s outcome (prognosis and recurrence) for GC patients. |
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