DNA methylation analysis of the SDC2, SEPT9 and VIM genes in fecal DNA for colorectal cancer diagnosis.

BACKGROUND: Colorectal cancer is one of the most common cancers worldwide. DNA methylation sites may serve as a new gene signature for colorectal cancer diagnosis. The search for representative DNA methylation sites is urgently needed. This study aimed to systematically identify a methylation gene panel for colorectal cancer diagnosis via tissue and fecal samples. METHODS: A total of 181 fecal and 50 tumor tissue samples were collected. They were obtained from 83 colorectal cancer patients and 98 healthy subjects. These samples were evaluated for DNA methylation of 9 target genes via quantitative bisulfite next-generation sequencing. We employed the rank-sum test to screen the colorectal cancer-specific methylation sites in the tissue and fecal cohorts. A data model was subsequently constructed and validated via the dedicated validation dataset. RESULTS: Compared with the fecal and negative control samples, the colorectal cancer tissue samples presented significantly higher methylation rates for all the selected gene sites. The methylation rates of the tissue and preoperative fecal samples showed the same high and low rates at the same sites. After screening, a panel of 29 loci in the SDC2, SEPT9, and VIM genes proved to be reliable biomarkers for colorectal cancer diagnosis in fecal samples. Logistic regression models were then constructed and validated using this panel. The sensitivity of the model was 91.43% (95% CI = [89.69, 93.17]), the specificity was 100% (95% CI = [100,100]), and the AUC value is 99.31% (95% CI = [99,99.62]). The diagnostic accuracy of the model for stage I and stage II colorectal cancer was 100% (11/11) and 91.3% (21/23), respectively. Overall, this study confirms that the gene locus panel and the model can be used to diagnose colorectal cancer effectively through feces. CONCLUSIONS: Our study identified a set of key methylation sites for colorectal cancer diagnosis from fecal samples, highlighting the importance of using tissue and fecal samples to accurately assess DNA methylation levels to screen for methylation sites, and developing an effective diagnostic model for colorectal cancer.

Efficient degradation of tetracycline hydrochloride by photocatalytic ozonation over Bi2WO6.

Photocatalytic ozonation technique for wastewater treatment has received much attention for their efficient capability in the mineralization of persistent organic pollutants. In this study, nanostructured Bi2WO6 was prepared by hydrothermal method and applied in the photocatalytic ozonation process for tetracycline hydrochloride (TCH) degradation under simulated solar light irradiation. Bi2WO6 triggered an effective synergy between photocatalysis and ozonation, and it showed a good activity and adaptability in the degradation of organic compounds. Besides, the influence of experimental factors on the total organic carbon removal (including catalyst dosage, ozone concentration, initial pH, reaction temperature and coexisting ions) was also investigated comprehensively. Spin-trapping electron paramagnetic resonance measurements and quenching experiments demonstrated that O2-, OH, 1O2 and h+ contributed to TCH degradation. The possible degradation pathways of TCH were proposed by identifying the intermediates with liquid chromatography-mass spectroscopy.