D Miller Seattle, WA, USA). Packaging cells were transfected with plasmids pTG 5391 (FB29 LTR-lacZ-SV40-Puro-LTR, clone E17-12 -TG 5391) or pTG 9344 (FB29 LTR-PGK-TK-IRES-Neo -LTR clone E 17-21 pTG 9344) to isolate the retroviral producer clone E17-12 -TG 5391 and E 17-21 TG 9344 (Transgene S.A., Strasbourg, France). PF-02341066 cell line The retroviral producer clone were cultured in DMEM supplemented with 4.5 g/L of glucose, 1% non-essential amino acids, 40 μg/ml gentamycin (Sigma) and 10% calf serum. Culture supernatant was harvested, filtered through a 0.45 μm nitrocellulose filter (Sartorius, Goettingen, Germany) and used in the presence of polybrene (Sigma) at 8 μg/ml final concentration.

NIH 3T3 fibroblasts were cultured in DMEM supplemented with 40 μg/ml gentamycin and 10% heat inactivated NBBS (GIBCO/BRL). Retroviral titration was determined by infecting NIH 3T3 fibroblasts with serial dilutions of the culture medium and staining respectively for β-galactosidase activity with X-gal protocol [26] or for HSV-TK expression using monoclonal antibody anti-HSV-TK as described below. All point titrations were performed four times. The titer of viral preparation was 4.9 (± 1.2) × 106 focus-forming units (FFU/ml) for TG 9344 and 1.7 (± 0.9) × 107 FFU/ml for TG 5391. The absence of competent replication helper retrovirus was checked by NIH 3T3 mobilization assay Treatment of cells with MTX, ara-c or aphidicolin

DHDK12 and HT29 cells were plated into 12 well plates at

5.105 cells/well and treated with SYN-117 mouse 0.08 μM methotrexate Rebamipide (Wyeth-Lederle, Puteaux, France) or 0.075 μM 1-β-D-arabinofuranosyl (Cytarabin-Pharmacia-Upjohn) or 25 μM aphidicolin (Sigma) for 24 hr. The concentrations of the drugs used in our study were chosen according to ABT 888 previously published studies [19, 21, 22]. Furthermore, we determined the IC50 of these drugs by a growth curve analysis. All concentrations used in our study were lower than the calculated IC50 (Table 1). After treatment, the drug-containing medium was removed; the cells were washed twice with phosphate-buffered saline (PBS) and fresh medium was provided. Every 2 to 6 hr during 72 hr, cell cycle distribution were obtained by flow cytometric determination of the DNA content of propidium-iodide (PI)-stained cells as described previously [27]. The cells were analyzed on a cytofluorometer EPICS XL-MCL (Coulter Beckman, Miami, USA) with an argon laser emitting at a wavelength of 488 nm. The analysis of fluorescence was carried out starting from an acquisition window determined by a two dimensional histogram representing the structure of the cells scaled to their size. This acquisition window was then used to produce a histogram representing the number of PI positive cells sorted by intensity of fluorescence, expressed in logarithmic curve mode. Table 1 IC50 of Methotrexate, Ara-C and Aphidicolin in DHDK12 and HT29 cell lines IC 50 Methotrexate Ara-C Aphidicolin DHDK12 cells 0.16 μM 40 μM 30 μM HT29 cells 0.