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Background There have been few available prognostic biomarkers in gastric cancer. We rigorously assessed the clinical relevance of promoter DNA methylation of Cysteine dioxygenase type 1 ( CDO1 ) gene, a cancer-specific aberration, in human gastric cancer. Methods Quantitative CDO1 methylation value (TaqMeth V) was initially calculated in 138 gastric cancer patients operated in 2005, and its clinical significance was elucidated. As a subsequent expanded set, 154 gastric cancer patients with pathological stage (pStage) II / III with no postoperative therapy were validated between 2000 and 2010. Results (1) Median TaqMeth V of CDO1 gene methylation of gastric cancer was 25.6, ranging from 0 to 120.9. As pStage progressed, CDO1 TaqMeth V became higher (p < 0.0001). (2) The optimal cut-off value was determined to be 32.6; gastric cancer patients with high CDO1 gene methylation showed a significantly worse prognosis than those with low CDO1 gene methylation (p < 0.0001). (3) A multivariate cox proportional hazards model identified high CDO1 gene methylation (p = 0.033) as an independent prognostic factor. (4) The results were recapitulated in the expanded set in pStage III, where high CDO1 gene methylation group had a significantly worse prognosis than low CDO1 gene methylation group (p = 0.0065). Hematogenous metastasis was unique in pStage III with high CDO1 gene methylation (p = 0.0075). (5) Anchorage independent growth was reduced in several gastric cancer cell lines due to forced expression of the CDO1 gene, suggesting that abnormal CDO1 gene expression may represent distant metastatic ability. Conclusions Promoter DNA hypermethylation of CDO1 gene was rigorously validated as an important prognostic biomarker in primary gastric cancer with specific stage.

We previously demonstrated that the lymph node ratio (LNR) is a prognostic factor associated with EGFR expression, among first priority genes amplified or overexpressed in cancer. Here, we investigated the associations between high LNR and second, third, and fourth priority genes. We performed mRNA expression microarray analysis of tumor tissue from patients with stage III gastric cancer and high or low LNRs. Candidate high LNR-associated genes were further evaluated in 39 patients with stage III gastric cancer. The functional relevance of these genes was evaluated in gastric cancer cell lines. We focused on five genes: H19,PEG10, IGF2BP3, CD177, and PGA3. H19 and PEG10 were confirmed as high LNR-associated genes. H19, PEG10, and IGF2BP3 were found to promote each other’s expression. Knocking down H19 or PEG10 using RNAi decreased cell proliferation, invasion, anchorage-independent growth, and chemoresistance. These genes had a mutual relationship in MKN7 cells. H19 knockdown decreased expression of epithelial-mesenchymal transition-associated genes in MKN74 cells to suppress transformation. Thus, H19 promotes epithelial-mesenchymal transition in gastric cancer and is a potential therapeutic target.

DNA markers for pancreatic ductal adenocarcinoma (PDAC) are urgently needed for detection of minimally invasive disease. The epigenetic relevance of the cysteine dioxygenase 1 gene (CDO1) has been never investigated in PDAC. Three studies, including cellular experiments, tissue validation, and pilot testing for pancreatic cytology, were carried out. Promoter DNA methylation value (MV) of CDO1 was quantified by quantitative methylation‐specific PCR. CDO1 expression was consistent with its promoter DNA methylation in 7 PDAC cell lines. In 160 retrospectively collected primary PDAC tumor tissues, MV was significantly higher compared to the corresponding noncancerous pancreas (area under the receiver operating characteristic curve [AUC] = 0.97, P < .0001), and CDO1 hypermethylation was highly specific to PDAC tumor tissues. CDO1 hypermethylation group (MV over 19) was significantly associated with diverse prognostic factors in PDAC. Surprisingly, it was significantly higher in prospectively collected PDAC cytology samples (n = 37), including both pancreatic juice (n = 12) and endoscopic ultrasound‐fine needle aspiration (EUS‐FNA) cytology (n = 25) compared to pancreatic benign diseases (AUC = 0.96, P < .0001). Detection of PDAC was confirmed by DNA testing in 35 of 37 patients (95% sensitivity); thus, it was more sensitive than cytology (33%) or EUS‐FNA cytology (88%). Promoter DNA methylation of CDO1 is extremely specific for PDAC tumors, and accumulates with PDAC tumor progression. It could be a definitive diagnostic marker of PDAC in pancreatic juice or EUS‐FNA cytology.

Purpose With the widespread use of definitive chemoradiotherapy (dCRT) for esophageal squamous cell carcinoma (ESCC), salvage surgery for recurrence/residual patients became prevalent. However, survival impact of salvage surgery remains obscure at present. Methods The updated clinical outcomes of salvage surgery were investigated to know its survival impact. Of the 155 ESCC patients who underwent dCRT between 2009 and 2016, we included 85 patients with recurrence or residual disease. The median follow-up was 65 months. Results Of the 85 patients with progression disease, there were 42 and 43 patients of recurrence and residual disease, respectively. Salvage surgery was performed in 27 patients after dCRT, including 15 patients who underwent salvage esophagectomy. The 5year overall survival (OS) of salvage surgery and otherwise patients was 66.1% and 14.5%, and the patients with salvage surgery had a significantly better prognosis (p < 0.0001). In the 15 patients who underwent salvage esophagectomy, residual disease, lymph node metastasis-positive (ycN+) after dCRT, and pathological lymph node metastasis-positive (ypN+) were significantly associated with poor prognosis (p = 0.0492, p = 0.0006, p = 0.0276), and the 5-year OS rates for the ycN/ypN combinations were 90%, 33.3%, and 0% in ycN−/ypN−, ycN+/ypN−, and ycN+/ypN+ patients, respectively (p = 0.0026). In a multivariate analysis, ycN+ was an independent poor prognostic factor (HR 13.6, 95% CI 1.65-286.8, p = 0.0154). Conclusions Survival impact of salvage surgery after dCRT is robust, and lymph node metastasis after dCRT may help determine the indication for salvage esophagectomy.