St three independent experiments. B) Cell proliferation in parental and subtoxic elisidepsin-treated cells. Cumulative numbers of cell divisions [shown as population doubling level (PDL)] are shown for MCF-7 and MiaPaCa-2 cells until passage 5. Proliferation of MCF-7 (IC50:0.4 mM) and MiaPaCa-2 (IC50:14 mM) cells was suppressed when elisidepsin was added to the culture at subtoxic doses (0.2 and 1 mM, respectively). The number of MiaPaCa-2 and MCF-7 seeded cells were 1.256105 and 1.46105, respectively. Each growth curve was performed at least twice with similar results, SDs are shown, 25033180 and each time point was performed in duplicate. P, passage. doi:10.1371/journal.pone.0053645.gtreatment, which would in turn result in the acquisition of BIBS39 price mesenchymal markers in these cells. We then performed western blot analysis of the cancer cell lines with acquired resistance and compared them to the corresponding parental control cells. We identified that the three different cancer cell types with acquired resistance to elisidepsin had altered basal levels of EMT markers (Fig. 5A). All resistant cell lines showed decreased E-cadherin, c-catenin and increased vimentin and Twist-1 expression. b-catenin expression was downregulated in the resistant HPAC and AsPC-1 cancer cell lines but upregulated in the MCF-7. In contrast, levels of Slug and Snail were upregulated in the resistant cancer cell lines HPAC and AsPC-1 but no differences were found in the breast carcinoma MCF-7 cell line. We also performed the same approach in different resistant cell lines from colon and lung (HCT116 and A549, respectively) with similar results (Fig. S4). Analysis by western blot confirmed that acquired resistance to elisidepsin is associated with a switch to the EMT state.Furthermore, we wanted to see if these cells also showed different expression levels of HER MedChemExpress 520-26-3 family members and proteins of their signaling pathways. We observed that the levels of all HER family members and their downstream signaling partners were downregulated in all resistant cancer cell lines (Figs. 5B and S4). A suppression of downstream signaling was similarly seen in the breast and pancreatic resistant cell lines, and the same expression pattern was also observed in other colon and lung resistant cell lines, highlighting the relevance of this phenomena.Modulation 23727046 of HER3 Affects Cancer Cell Line Sensitivity to ElisidepsinBased on previous studies from our group and others demonstrating that elisidepsin downregulates the HER3 receptor tyrosine kinase and that high expression of HER3 is prevalent in a broad number of different tumor cells, we investigated if modulation of protein expression levels of the HER3 receptorEMT and HER3 Predicts Elisidepsin SensitivityFigure 2. Expression of EMT markers associated with elisidepsin sensitivity in breast cancer cell lines. Protein expression levels of different EMT markers were evaluated by immunocytochemistry (A), western blot (B) and IHC (C). A) Immunocytochemistry of two epithelial (Ecadherin and b-catenin) and four mesenchymal markers (vimentin, Slug, Snail and Twist). Magnification 100x. B) E-cadherin, b-catenin, Slug, Snail, Twist, vimentin and b-actin (loading control) were detected by western blot analysis using 50 mg of total protein. C) Basal levels of E-cadherin, bcatenin and vimentin were analyzed by IHC. Magnification 20x. Each experiment was performed at least in duplicate. doi:10.1371/journal.pone.0053645.gaffects sensitivity to elisidepsin in a.St three independent experiments. B) Cell proliferation in parental and subtoxic elisidepsin-treated cells. Cumulative numbers of cell divisions [shown as population doubling level (PDL)] are shown for MCF-7 and MiaPaCa-2 cells until passage 5. Proliferation of MCF-7 (IC50:0.4 mM) and MiaPaCa-2 (IC50:14 mM) cells was suppressed when elisidepsin was added to the culture at subtoxic doses (0.2 and 1 mM, respectively). The number of MiaPaCa-2 and MCF-7 seeded cells were 1.256105 and 1.46105, respectively. Each growth curve was performed at least twice with similar results, SDs are shown, 25033180 and each time point was performed in duplicate. P, passage. doi:10.1371/journal.pone.0053645.gtreatment, which would in turn result in the acquisition of mesenchymal markers in these cells. We then performed western blot analysis of the cancer cell lines with acquired resistance and compared them to the corresponding parental control cells. We identified that the three different cancer cell types with acquired resistance to elisidepsin had altered basal levels of EMT markers (Fig. 5A). All resistant cell lines showed decreased E-cadherin, c-catenin and increased vimentin and Twist-1 expression. b-catenin expression was downregulated in the resistant HPAC and AsPC-1 cancer cell lines but upregulated in the MCF-7. In contrast, levels of Slug and Snail were upregulated in the resistant cancer cell lines HPAC and AsPC-1 but no differences were found in the breast carcinoma MCF-7 cell line. We also performed the same approach in different resistant cell lines from colon and lung (HCT116 and A549, respectively) with similar results (Fig. S4). Analysis by western blot confirmed that acquired resistance to elisidepsin is associated with a switch to the EMT state.Furthermore, we wanted to see if these cells also showed different expression levels of HER family members and proteins of their signaling pathways. We observed that the levels of all HER family members and their downstream signaling partners were downregulated in all resistant cancer cell lines (Figs. 5B and S4). A suppression of downstream signaling was similarly seen in the breast and pancreatic resistant cell lines, and the same expression pattern was also observed in other colon and lung resistant cell lines, highlighting the relevance of this phenomena.Modulation 23727046 of HER3 Affects Cancer Cell Line Sensitivity to ElisidepsinBased on previous studies from our group and others demonstrating that elisidepsin downregulates the HER3 receptor tyrosine kinase and that high expression of HER3 is prevalent in a broad number of different tumor cells, we investigated if modulation of protein expression levels of the HER3 receptorEMT and HER3 Predicts Elisidepsin SensitivityFigure 2. Expression of EMT markers associated with elisidepsin sensitivity in breast cancer cell lines. Protein expression levels of different EMT markers were evaluated by immunocytochemistry (A), western blot (B) and IHC (C). A) Immunocytochemistry of two epithelial (Ecadherin and b-catenin) and four mesenchymal markers (vimentin, Slug, Snail and Twist). Magnification 100x. B) E-cadherin, b-catenin, Slug, Snail, Twist, vimentin and b-actin (loading control) were detected by western blot analysis using 50 mg of total protein. C) Basal levels of E-cadherin, bcatenin and vimentin were analyzed by IHC. Magnification 20x. Each experiment was performed at least in duplicate. doi:10.1371/journal.pone.0053645.gaffects sensitivity to elisidepsin in a.