In our previous work, cellular prion protein (PrPc) was identified as an upregulated gene in adriamycin-resistant gastric carcinoma cell line SGC7901/ADR compared to its parental cell line SGC7901. Here we investigate the expression of PrPc in gastric cancer and whether it was involved in multidrug resistance (MDR) of gastric cancer. We demonstrated that PrPc was ubiquitously expressed in gastric cancer cell lines and tissues. PrPc conferred resistance of both P-glycoprotein (P-gp)-related and P-gp-nonrelated drugs on SGC7901, which was accompanied by decreased accumulation and increased releasing amount of adriamycin in PrPc-overexpressing cell line. Inhibition of PrPc expression by antisense or RNAi technology could partially reverse multidrugresistant phenotype of SGC7901/ADR. PrPc significantly upregulated the expression of the classical MDR-related molecule P-gp but not multidrug resistance associated protein and glutathione S-transferase pi. The PrPc-induced MDR could be partially reversed by P-gp inhibitor verapamil. PrPc could also suppress adriamycin-induced apoptosis and alter the expression of Bcl-2 and Bax, which might be another pathway contributing to PrPcrelated MDR. The further study of the biological functions of PrPc may be helpful for understanding the mechanisms of occurrence and development of clinical gastric carcinoma and PrPc-related MDR and developing possible strategies to treat gastric cancer.

The main etiopathogenesis of rheumatoid arthritis (RA) is overexpressed inflammatory cytokines and tissue injury mediated by persistent NF-κB activation. MicroRNAs widely participate in the regulation of target gene expression and play important roles in various diseases. Here, we explored the mechanisms of microRNAs in RA. We found that microRNA (miR)-10a was downregulated in the fibroblast-like synoviocytes (FLSs) of RA patients compared with osteoarthritis (OA) controls, and this downregulation could be triggered by TNF-α and IL-1β in an NF-κB-dependent manner through promoting the expression of the YingYang 1 (YY1) transcription factor. Downregulated miR-10a could accelerate IκB degradation and NF-κB activation by targeting IRAK4, TAK1 and BTRC. This miR-10a-mediated NF-κB activation then significantly promoted the production of various inflammatory cytokines, including TNF-α, IL-1β, IL-6, IL-8, and MCP-1, and matrix metalloproteinase (MMP)-1 and MMP-13. In addition, transfection of a miR-10a inhibitor accelerated the proliferation and migration of FLSs. Collectively, our data demonstrates the existence of a novel NF-κB/YY1/miR-10a/NF-κB regulatory circuit that promotes the excessive secretion of NF-κB-mediated inflammatory cytokines and the proliferation and migration of RA FLSs. Thus, miR-10a acts as a switch to control this regulatory circuit and may serve as a diagnostic and therapeutic target for RA treatment.

No abstract

Cytokine-induced antiapoptosis inhibitor 1 (CIAPIN1) is a newly identified antiapoptosis molecule and a mediator of gastric MDR. We cloned cDNA of human CIAPIN1 by RT-PCR and constructed prokaryotic expression vectors of human CIAPIN1 by inserting human CIAPIN1 coding region into pET28-a(+) and pGEX- 4T-1, respectively. The fusion proteins were expressed in Escherichia coli and purified by affinity chromotography. Monoclonal antibody (MAb) against CIAPIN1 was obtained with standard cell fusion technique and ELISA screening. Immunohistochemistry and Western blot showed that the anti-CIAPIN1 MAb recognizes human and mouse CIAPIN1 protein in both native and denatured form. Western blotting confirmed that the expression of CIAPIN1 was upregulated in MDR gastric cancer cell lines. This MAb will be a useful tool for the detection of CIAPIN1 protein in future studies.