Enzymatic inhibition of MICA sheddase ADAM17 by lomofungin in hepatocellular carcinoma cells.

In our previous study on hepatocellular carcinoma (HCC) susceptibility genes in chronic hepatitis patients, we identified the MHC class I polypeptide-related sequence A (MICA). Natural killer cells eliminate various cancer cells, including HCC, by suppressing MICA shedding. Therefore, we investigated MICA sheddases and inhibitors for HCC immunotherapy. In this study, HepG2, PLC/PRF/5, and Hep3B were treated with the siRNA of a disintegrin and metalloproteases (ADAMs) and matrix metalloproteases to measure the concentration of soluble MICA (sMICA) by ELISA to detect the therapeutic target. Furthermore, an FDA-approved drug library was tested for the enzymatic inhibition of the targeted enzyme in an in vitro drug screening assay system. ADAM17 knockdown reduced sMICA levels and increased membrane-bound MICA (mMICA) expression in HCC cells. In an in vitro drug screen using an FDA-approved drug library, lomofungin, an antifungal drug, was found to strongly decrease ADAM17 activity. In HCC cells, mMICA expression was induced and sMICA production was inhibited in a dose-dependent manner. These effects were cancelled upon ADAM17 knockdown, suggesting that lomofungin targeted ADAM17. Analysis of lomofungin analogs revealed the responsible functional groups. In summary, we suggest lomofungin to be an attractive agent for the immunological control of HCC, via the suppression of ADAM17.

Predominance of regorafenib over sorafenib: Restoration of membrane-bound MICA in hepatocellular carcinoma cells.

BACKGROUND AND AIM: The multi-kinase inhibitor regorafenib (REG) was recently demonstrated to be effective in patients with sorafenib (SOR)-resistant hepatocellular carcinoma (HCC). Interestingly, SOR is known to enhance the accumulation of membrane-bound MHC class I polypeptide-related sequence A (mMICA) in HCC cells and to block the production of soluble MICA (sMICA), an immunological decoy. In addition, MICA is associated with HCC in patients with chronic hepatitis C. We have now compared the impact of REG and SOR on MICA in HCC cells, as well as the immunotherapeutic implications thereof. METHODS: HepG2 and PLC/PRF/5 cells were exposed to REG and SOR, and levels of sMICA and mMICA were measured by ELISA and flow cytometry, respectively. The drugs were also tested in vitro for inhibitory activity against recombinant human A disintegrin and metalloprotease 9 (ADAM9), a sheddase that releases MICA from the membrane. RESULTS: To a greater extent than SOR, but without marked difference in cytotoxicity, REG significantly suppressed mRNA and protein expression of ADAM9 and ADAM10, thereby decreasing production of sMICA and boosting accumulation of mMICA. Accumulation of mMICA in response to REG was reversed by siRNA against ADAM9. However, the drugs did not inhibit the enzymatic activity of ADAM9 in vitro. CONCLUSIONS: The clinical superiority of REG over SOR is partially attributable to reduced MICA shedding via transcriptional suppression of ADAM9 and ADAM10.

miR-425 regulates inflammatory cytokine production in CD4+ T cells via N-Ras upregulation in primary biliary cholangitis.

BACKGROUND & AIMS: Primary biliary cholangitis (PBC) is an autoimmune liver disease of unknown pathogenesis. Consequently, therapeutic targets for PBC have yet to be identified. CD4+ T cells play a pivotal role in immunological dysfunction observed in PBC, and therefore, microRNA (miRNA) and mRNA expression were analysed in CD4+ T cells, to investigate PBC pathogenesis and identify novel therapeutic targets. METHODS: Integral miRNA and mRNA analysis of 14 PBC patients and ten healthy controls was carried out using microarray and quantitative real-time polymerase chain reaction (qRT-PCR), with gene set enrichment analysis. The functional analyses of miRNA were then assessed using reporter and miRNA-overexpression assays. RESULTS: The integral analysis of miRNA and mRNA identified four significantly downregulated miRNAs (miR-181a, -181b, -374b, and -425) related to the T cell receptor (TCR) signalling pathway in CD4+ T cells of PBC. N-Ras, a regulator of the TCR signalling pathway, was found to be targeted by all four identified miRNAs. In addition, in vitro assays confirmed that decreased miR-425 strongly induced inflammatory cytokines (interleukin [IL]-2 and interferon [IFN]-γ) via N-Ras upregulation in the TCR signalling pathway. CONCLUSION: The decreased expression of four miRNAs that dysregulate TCR signalling in PBC CD4+ T cells was identified. miR-425 was demonstrated as an inflammatory regulator of PBC via N-Ras upregulation. Therefore, the restoration of decreased miR-425 or the suppression of N-Ras may be a promising immunotherapeutic strategy against PBC. LAY SUMMARY: Primary biliary cholangitis (PBC) is an autoimmune liver disease, but the causes are unknown. MicroRNAs are molecules known to regulate biological signals. In this study, four microRNAs were identified as being decreased in PBC patients, leading to activation of T cell receptor signalling pathways, involved in inflammation. One particular target, N-Ras, could be an attractive and novel immunotherapeutic option for PBC. TRANSCRIPT PROFILING: Microarray data are deposited in GEO (GEO accession: GSE93172).