BackgroundFunctional erythropoietin (EPO) signaling is not specific only to erythroid lineages and has been confirmed in several solid tumors, including breast. Three different isoforms of erythropoietin receptor (EPOR) have been reported, the soluble (EPOR-S) and truncated (EPOR-T) forms acting antagonistically to the functional EPOR. In this study, we investigated the effect of human recombinant erythropoietin (rHuEPO) on cell proliferation, early gene response and the expression of EPOR isoforms in the MCF-7 breast cancer cell line.Materials and methodsThe MCF-7 cells were cultured with or without rHuEPO for 72 h or 10 weeks and assessed for their growth characteristics, expression of early response genes and different EPOR isoforms. The expression profile of EPOR and EPOR-T was determined in a range of breast cancer cell lines and compared with their invasive properties.ResultsMCF-7 cell proliferation after rHuEPO treatment was dependent on the time of treatment and the concentration used. High rHuEPO concentrations (40 U/ml) stimulated cell proliferation independently of a preceding long-term exposure of MCF-7 cells to rHuEPO, while lower concentrations increased MCF-7 proliferation only after 10 weeks of treatment. Gene expression analysis showed activation of EGR1 and FOS, confirming the functionality of EPOR. rHuEPO treatment also slightly increased the expression of the functional EPOR isoform, which, however, persisted throughout the 10 weeks of treatment. The expression levels of EPOR-T were not influenced. There were no correlations between EPOR expression and the invasiveness of MCF-7, MDA-MB-231, Hs578T, Hs578Bst, SKBR3, T-47D and MCF-10A cell lines.ConclusionsrHuEPO modulates MCF-7 cell proliferation in time- and concentration-dependent manner. We confirmed EGR1, FOS and EPOR as transcription targets of the EPO-EPOR signaling loop, but could not correlate the expression of different EPOR isoforms with the invasiveness of breast cancer cell lines.

Electrochemotherapy is a local treatment for skin tumors and also deep seated tumors and metastases. Electrochemotherapy is based on enhanced cytotoxic effectiveness of bleomycin or cisplatin by electroporation, which increases drug delivery into cells in tumors. Electrochemotherapy is an ablative technique of high effectiveness with over 80% objective responses of electrochemotherapy treated tumors. Its advantage is the simplicity of the procedure that can be utilized in treatment of different tumor histiotypes. Currently it is predominantly used in palliative intent when the other treatment options have been exhausted. For the translation of electrochemotherapy into the clinics also the technological development that is now focusing into the treatment of deep-seated tumors was important. In Slovenia we are at the forefront in the treatment of liver tumors and head and neck tumors, while the others are developing electrochemotherapy for treatment of bone and brain metastases as well as endoluminal tumors.