2-Acetyl-amino-1,3,4,6-tetra-O-(tri-methyl-silyl)-2-de-oxy-α-d-gluco-pyran-ose.

The title compound, C20H47NO6Si4, was synthesized by per-O-tri-methyl-silylation of N-acetyl-d-glucosa-mine using chloro-tri-methyl-silane in the presence of hexa-methyl-disiloxane. The tri-methyl-silyl group and acetamido group are located on the same side of the pyran ring, showing an α-configuration glycoside. One of the tri-methyl-silyl groups is disordered over two orientations, with site-occupancy factors of 0.625 (9) and 0.375 (9). In the crystal, N-H⋯O hydrogen bonds link the mol-ecules into supra-molecular chains along the a-axis direction.

Promoter methylation of CHFR gene in gastric carcinoma tissues detected using two methods.

BACKGROUND AND OBJECTIVE: Transcriptional silencing induced by CpG island methylation is believed to be one of the important mechanisms of carcinogenesis. Checkpoint with fork head-associated and ring finger (CHFR) governs the transition from prophase to prometaphase in response to mitotic stress. This study was to analyze the relationship between the methylation of CHFR gene and the clinicopathologic features of gastric cancer, and the difference of results between methylation-specific polymerase chain reaction (MSP) and combined bisulfite restriction analysis (COBRA) in detecting aberrant methylation of CHFR gene in gastric cancer. METHODS: Both MSP and COBRA methods were used to detect the promoter methylation of CHFR gene in gastric cancer specimens from 64 patients. The relationship between methylation status of CHFR gene and the clinicopathologic features of gastric cancer were analyzed using SPSS16.0. RESULTS: The methylation rates of CHFR gene promoter were significantly higher in gastric cancer samples than in the corresponding paracancer normal gastric mucosa by MSP (51.6% vs. 18.8%, P < 0.001). However, there was no significant correlation between methylation status of CHFR gene and the clinicopathologic parameters of gastric cancer, including age, gender, tumor size, clinical stage, Borrman type, tumor invasion depth, differentiation, and lymph node metastasis (P > 0.05). Aberrant methylation of the CHFR gene was detected in 27 (42.2%) of the 64 specimens of gastric cancer using COBRA, which did not significantly differ from that using MSP (P > 0.05). CONCLUSIONS: Aberrant methylation of the CHFR gene is a frequent event in the carcinogenesis of gastric cancer. Detecting the methylation of CHFR gene in gastric mucosa may conduce to the diagnosis of gastric cancer. No difference was found between MSP and COBRA in detecting promoter methylation of CHFR gene in gastric cancer.

Promoter methylation of p16, Runx3, DAPK and CHFR genes is frequent in gastric carcinoma.

AIMS AND BACKGROUND: Transcriptional silencing induced by hypermethylation of CpG islands in the promoter regions of genes is believed to be an important mechanism of carcinogenesis in human cancers including gastric cancer. A number of reports on methylation of various genes in gastric cancer have been published, but most of these studies focused on cancer tissues or only a single gene. In this study, we determined the promoter hypermethylation status and mRNA expression of 4 genes: p16, Runx3, DAPK and CHFR. METHODS: Methylation-specific polymerase chain reaction (MSP) was used to determine the methylation status of p16, Runx3, DAPK and CHFR gene promoters in cancer and adjacent normal gastric mucosa specimens from 70 patients with gastric cancer, as well as normal gastric biopsy samples from 30 people without cancer serving as controls. In addition, the mRNA expression of p16, Runx3, DAPK and CHFR was investigated in 34 gastric cancer patients by RT-PCR. Bisulfite DNA sequence analysis was applied to check the positive samples detected by MSP. RESULTS: When carcinoma specimens were compared with adjacent normal gastric mucosa samples, a significant increase in promoter methylation of p16, Runx3, DAPK and CHFR was observed, while all 30 histologically normal gastric specimens were methylation free for all 4 genes. The methylation rate of the 4 genes increased from normal stomach tissue to tumor-adjacent gastric mucosa to gastric cancer tissue. Concurrent methylation in 2 or more genes was found in 22.9% of tumor-adjacent normal gastric mucosa and 75.7% of cancer tissues. No correlation was found between hypermethylation and other clinicopathological parameters such as sex, age, and tumor location. However, the frequency of DAPK and CHFR methylation in cancer tissues was significantly associated with the extent of differentiation and lymph node metastasis (P < 0.05) and the frequency of Runx3 methylation was significantly associated with tumor size (P < 0.05). Weak expression and loss of expression of the 4 genes was observed in cancer tissues and was significantly associated with promoter hypermethylation (P < 0.05). CONCLUSIONS: Promoter hypermethylation of p16, Runx3, DAPK and CHFR is frequent in gastric cancer. DAPK and CHFR promoter hypermethylation may be an important help in evaluating the differentiation grade and lymph node status of gastric cancer. Weak gene expression and loss of gene expression due to promoter hypermethylation may be a cancer-specific event.