Complementary primers were annealed and cloned into the vector pLVX-shRNA1 (Clontech Laboratories, USA) using the restriction sites BamHI and EcoRI (NEB-Biolabs, USA). To produce infectious viral particles, Lenti-X 293T cells were transient-transfected by Lentiphos HT/Lenti-X HT Packaging Systems with lentiviral vectors pLVX-Puro or pLVX-shRNA1-E9 or pLVX-shRNA1-E13 as described by the manufacturer (Clontech Laboratories, USA). After 48 h, supernatants were checked with Lenti-X GoStix (Clontech Laboratories, USA) to determine whether sufficient viral particles were produced before transducing target cells. Supernatants were filtered through a 0.22-μm PES filter to eliminate detached cells,

were aliquoted, and subsequently stored at ‒80°C until use. Jurkat and K562 cells (2.5 × 105) were transduced with approximately 4.5 × 105 IFU/mL of supernatants. RNA extractions were obtained after at least 2 weeks of puromycin selleck kinase inhibitor selection (1 μg/mL). Cell survival determination Cell survival was determined by cleavage of tetrazolium salt WST-1 to formazan by cellular mitochondrial dehydrogenase enzymes. After different treatment periods, cells 5-Fluoracil molecular weight were incubated with 10 μL/well of WST-1/ECS solution (BioVision Research, Mountain View,

CA, USA) for 3 h. Absorbance (450 nm) of treated and untreated samples was determined on a microtiter plate reader (Synergy™ HT Multi-Mode Microplate Reader; Biotek, Winooski, VT, USA). Data are reported as percentage of cell survival taking untreated control cells as 100% of cell survival. Apoptosis detection Cell death was measured by flow cytometry using propidium iodide (cat. no. P4864, Sigma-Aldrich) and Annexin-V-FlUOS (cat. no. 1828681, Roche Applied Science) as recommended by these manufacturers. Cells were seeded in 6-well plates at a density of 3 × 105 cells per well in 1 mL

RPMI medium containing or not etoposide Phenylethanolamine N-methyltransferase (170 μM). After 5, 15, and 25 h, each sample was analyzed in a FACS Aria cytometer (BD Biosciences). Acknowledgements We thank our technicians María de Jesús Delgado-Ávila and Leticia Ramos-Zavala for their efficient support. This work was supported by grants CB-2005-25121/51502-M (CONACyT-México), FIS/2005/1/I/022, and FIS/2006/1A/I/051 (IMSS) to LFJ-S. Electronic supplementary material Additional file 1: Modulation of PBX1-4 expression after etoposide treatment. Jurkat and CEM cells were treated with 170 μM etoposide for 1 and 2 h; thereafter, total RNA was extracted and retrotranscribed. Real time-PCR assays were performed to determine the relative expression levels of PBX1-4. Expression analysis was carried out by normalizing with non-treated cells and employing RPL32 as reference gene. The bars represent means ± Standard deviations (SD) of two independent experiments. (JPEG 308 KB) References 1.