Fig. 1

PCV2 ORF3 overexpression induces apoptosis in cancer cells. a Representative FACS analysis of apoptosis in human monocytic cell line THP-1, transfected with either empty pcDNA3.1 (left), or pcDNA3-ORF3 (right). Cells were stained by annexin-V-FITC (x-axis) and propidium iodide (y-axis) and analyzed at 48 h post-transfection by flow cytometry. Annexin-V-FITC single-positive cells (annexin+/PI-) correspond to early apoptotic cells, double-positive cells (annexin+/PI+) to late apoptotic, while double-negative cells (annexin-/PI-) represent non-apoptotic cells, and PI single-positive cells (annexin-/PI+) necrotic cells. In each quadrant, the percentage of cells out the FSC/SSC gate set-up for each cell line, is indicated. b Proportion of apoptotic cells (annexin+/PI- and annexin+/PI+) among cells overexpressing ORF3 (dark grey) or in controls (light grey); B16F10 mouse melanoma cells, metastatic A375M human melanoma cells, filamin-A-deficient M2 human melanoma cells, and THP-1 human acute monocytic leukemia cells were transfected and analyzed c. Caspase inhibition assay on B16F10 mouse melanoma cells and Porcine kidney 15 (PK15) cells. Cells were treated with pan-caspase inhibitor, then transfected with a plasmid expressing ORF3 or with pcDNA3-ORF3. Percentages of apoptotic cells (annexin+/PI- and annexin+/PI+) were quantified in cells overexpressing ORF3 (dark grey) and in controls (light grey). Error bars indicate standard deviations from 6 analyses. ***: Student test p < 0.005