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Purpose MicroRNA-218 (miR-218) is a key regulator of numerous processes relevant to tumor progression. In the present study, we aimed to characterize the relationship between miR-218 and the Epidermal Growth Factor Receptor (EGFR) as well as to understand downstream effects in triple-negative breast cancer (TNBC). Methods We assessed miR-218 and EGFR expression in cell lines and publicly available primary breast cancer gene expression data. We then overexpressed miR-218 in two TNBC cell lines and investigated effects on EGFR and downstream mitogen-activated protein (MAP) kinase signaling. Luciferase reporter assay was used to characterize a direct binding interaction between miR-218 and EGFR mRNA. Digital holographic microscopy helped investigate cell migration and dry mass after miR-218 overexpression. Cell division and invasion were assessed microscopically, while radiation response after miR-218 overexpression alone or combined with additional EGFR knockdown was investigated via clonogenic assays. Results We found an inverse correlation between EGFR expression and miR-218 levels in cell lines and primary breast cancer tissues. MiR-218 overexpression resulted in a downregulation of EGFR via direct binding of the mRNA. Activation of EGFR and downstream p44/42 MAPK signaling were reduced after pre-miR-218 transfection. Cell proliferation, motility and invasiveness were inhibited whereas cell death and mitotic catastrophe were upregulated in miR-218 overexpressing cells compared to controls. MiR-218 overexpressing and EGFR siRNA-treated cells were sensitized to irradiation, more than miR-218 overexpressing cells alone. Conclusion This study characterizes the antagonistic relationship between miR-218 and EGFR. It also demonstrates downstream functional effects of miR-218 overexpression, leading to anti-tumorigenic cellular changes.

Background. qRT-PCR investigations on patient specimen seem to be the only probable laboratory technology to validate the current individual SARS-CoV-2 status correctly. This kind of nucleic acid amplification technology is available in most countries, but missing in resource limited areas with poor laboratory infrastructure. The most feasible way to build up PCR test capacities for SARS-CoV-2 in these areas is the use of conventional PCR. PCR-thermocycler and gel-electrophoresis systems could be shipped easily by parcel service to the whole world, because they are almost maintenance free and need no engineers for their installation and service. Methods. In order to reduce the complexity of sensitive reagent kits we have developed a freeze dried test kit for the traditional RT-PCR for the detection of SARS-CoV-2 in single ready to use tubes. Transport and storage of the reagents are now free of any cooling chain.Results. We have analysed 244 patient samples and compared the results to the SEEGENE Allplex™ 2019-nCoV assay. The sensitivity and specificity were 95.5% and 98.5%, respectively. Next to these performance parameters we could implement a workflow for processing 96 patient samples in parallel, handled by only 1 laboratory technician in an 8 hours working day.Conclusion. The use of conventional PCR in combination with gel-electrophoresis for test analysis is a feasible approach to make SARS-CoV-2 diagnostic available in the whole world. This is needed urgently, because SARS-CoV-2 is a question of global health and not only of the well-equipped countries.