The optical system was configured with a 75 W Xe lamp, circular light polarizer and end-mounted photomultiplier. The instrument had previously been calibrated with (D)-camphorsulfonic acid. Temperature was regulated using a Neslab RTE-300 circulating programmable water bath (Neslab Inc). CD spectra were recorded at 298 K in a 10 mm path length cell over a wavelength range of 215–345 nm in steps of either 1 0r 2 nm, with

3 nm entrance/exit slit widths: the number of counts was set to 10,000 with adaptive sampling Ro 61-8048 cell line set to 500,000. The spectra were corrected by subtracting the spectrum of the same buffer solution of 100 mM potassium chloride and 10 mM potassium phosphate at pH 7.0. Annealing and melting profiles were recorded using a thermoelectric temperature

controller (Melcor) on 4 μM DNA samples with and without 3.5 mol.equiv. of ligands using 0.5 K temperature increments and a cooling or heating rate of 0.2 K/min over the temperature range 298-368 K. Cells and culture conditions BJ fibroblasts expressing PSI-7977 solubility dmso hTERT (BJ-hTERT) or hTERT and SV40 early region (BJ-EHLT), were obtained as previously reported [15]. Cells were grown in Dulbecco Modified Eagle Medium (D-MEM, Invitrogen Carlsbad, CA, USA) supplemented with 10% fetal calf serum, 2 mM L-glutamin and antibiotics. Proliferation assay 5 × 104 cells were seeded in 60-mm Petri plates (Nunc, MasciaBrunelli, Milano, Italy) and 24 h after plating, 0.5 μM of freshly dissolved compound was added to the culture medium. Cell counts (Coulter Counter, Kontron Instruments, Milano, Italy) and viability (trypan blue dye exclusion) were determined daily, from day 2 to day 8 of culture. Immunofluorescence Cells were fixed in 2% formaldehyde and permeabilized in 0.25% Triton X100 in PBS for 5 min at Rolziracetam room temperature. For immunolabeling, cells were incubated with primary antibody, then washed in PBS and incubated with the secondary antibodies. The following primary antibodies were used: pAb and mAb anti-TRF1 (Abcam Ltd.; Cambridge UK); mAb (Upstate, Lake Placid, NY) and pAb anti-γH2AX (Abcam). The following secondary antibody were

used: TRITC learn more conjugated Goat anti Rabbit, FITC conjugated Goat anti Mouse (Jackson ImmunoResearch Europe Ltd., Suffolk, UK). Fluorescence signals were recorded by using a Leica DMIRE2 microscope equipped with a Leica DFC 350FX camera and elaborated by a Leica FW4000 deconvolution software (Leica, Solms, Germany). This system permits to focus single planes inside the cell generating 3D high-resolution images. For quantitative analysis of γH2AX positivity, 200 cells on triplicate slices were scored. For TIF’s analysis, in each nucleus a single plane was analyzed and at least 50 nuclei per sample were scored. Fluorescence in situ hybridization (FISH) For metaphase chromosome preparation cells were treated with demecolcine (Sigma, Milan, Italy) 0.