High-Throughput Sequencing Reveals the Differential MicroRNA Expression Profiles of Human Gastric Cancer SGC7901 Cell Xenograft Nude Mouse Models Treated with Traditional Chinese Medicine Si Jun Zi Tang Decoction

Objective. The present study aimed to investigate the potential mechanism underlying the antitumor effect of Si Jun Zi Tang (SJZT) decoction on gastric cancer. Methods. Twelve human gastric cancer SGC7901 cell xenograft nude mouse models were established. The mice were randomly divided into the Model group and SJZT group. SJZT exerted significant antitumor effects after 21 days of decoction administration. High-throughput sequencing was used to analyze the microRNA (miRNA) expression profiles of tumor tissues. Bioinformatics analysis was performed to provide further information regarding the differentially expressed miRNAs. Five representative differentially expressed miRNAs and four predicted target genes were further validated using quantitative real-time reverse transcription PCR (qRT-PCR). Results. We identified 33 miRNAs that were differentially expressed in the SJZT group compared with the Model group. Among them, 32 miRNAs were upregulated and 1 miRNA was downregulated. Bioinformatic analysis showed that most of miRNAs acted as tumor suppressors and their target genes participated in multiple signaling pathways, including the PI3K/Akt signaling pathway, microRNAs in cancer, and Wnt signaling pathway. The qRT-PCR result confirmed that miR-223-3p, miR-205-5p, miR-147b-3p, and miR-223-5p were overexpressed and their respective paired target genes FUT9, POU2F1, MUC4, and RAB14 mRNA were obviously downregulated in the SJZT group compared with those in the Model group. Network analysis revealed that miR-223-3p and miR-205-5p shared two targets POU2F1 (encoding POU class 2 homeobox 1) and FUT9 (encoding fucosyltransferase 9), suggesting they have a common role in certain pathways. Conclusion. This study provided novel insights into the anticancer mechanism of SJZT against gastric cancer, which might be partly related to the modulation of miRNA expression and their target pathways in tumors.

Methylation regulation of MUC6 correlates with metastasis of gastric cancer

Background: The aim of this study was to investigate the mechanism of the downregulation of MUC6 and its influence on GC metastasis.Methods: The expression of MUC6 was examined in cancer tissues and their corresponding adjacent normal tissues in 40 gastric adenocarcinoma patients. The investigation of methylation level of MUC6 promoter region in gastric cell lines and gastric specimen tissues was performed through immunohistochemistry and/or quantitative polymerase chain reaction (qPCR)s. MUC6 was knocked down in GES-1 cell lines and overexpressed in SGC7901 cell lines; the effects of MUC6 knockdown and overexpression on cell migration and invasion were examined using Transwell migration assay. The effects of demethylation and methylation on MUC6 expression were examined using Western blot, qPCR, or double luciferase report experiment.Results: The expression of MUC6 in GC tissues was significantly lower than that in normal paracancerous tissues. While the cells migration and invasion abilities were decreased significantly after overexpression of MUC6, these abilities increased significantly after the knocking down of MUC6. The methylation levels of MUC6 in GC tissues and GC cell lines (MGC803, MKN45, AGS, SGC7901, and BGC823) were significantly higher than those in paracancerous tissues and gastric epithelial cells. The promoter methylation could significantly reduce the binding of MUC6 promoter region to the related transcription factors. The expression of MUC6 increased with the concentration of demethylated drugs and the time of action.Conclusion: The expression of MUC6 was regulated by methylation of its promoter, and this methylation of MUC6 promoter may lead to significant downregulation of MUC6 in GC and promote the metastasis of GC.

UHRF1 mediates cell migration and invasion of gastric cancer

Gastric cancer (GC) is a common highly aggressive malignant tumor in worldwide. Ubiquitin-like with PHD and ring-finger protein 1 (UHRF1) has a key role in several kinds of cancers development. However, the biology effect of UHRF1 on the tumorigenesis of GC remains unclear. In this research, the role of UHRF1 in the growth, migration, invasion and apoptosis and the underlying mechanisms were investigated in MGC803 and SGC7901 cells. The UHRF1 knockdown MGC803 and SGC7901 cell lines were used to investigate the roles of UHRF1 on GC cell growth, migration, invasion and apoptosis. The growth, migration and invasion rate of UHRF1 knockdown cells was lower than that of the control. Moreover, ROS generation and caspase-3/caspase-9 activities increased in UHRF1 knockdown cells. And mitochondrial membrane potential decreased in UHRF1 knockdown cells. These findings indicated that UHRF1 promoted the growth, migration and invasion of MGC803 and SGC7901 cells and inhibited apoptosis via a ROS-associated pathway.