4.2. Cell Lines

Dr. Elda Tagliabue (Molecular Targeting Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione Institute of Hospitalization and Scientific Care, National Cancer Institute, Milan, Italy) kindly provided us the human breast cancer cell lines: MDA-MB-231(ATCC: HTB-26—Rockville, MD, USA) and SUM 149 (SUM149PT—Asterand Bioscience Detroit, MI). The first was cultured in RPMI-1640 and the second was cultured in DMEM/F-12 supplemented with insulin (5 μg/mL). The cells were authenticated using the short tandem repeat profiling method in their Institute. Prof. Giulio Ghersi (STEBICEF Department, University of Palermo, Italy) kindly provided us the non-tumorigenic cell line 1-7HB2 (ECACC 10081201—Cancer Research Technology, London, UK) that was cultured in DMEM low glucose supplemented with hydrocortisone (5 μg/mL) and insulin (10 μg/mL). HL60, obtained from ATCC^® (CCL-240, Rockville, MD, USA), and its variant HL60R, obtained by exposure to gradually increasing concentrations of doxorubicin, were cultured in RPMI-1640. All media were supplemented with 10% heat-inactivated fetal calf serum, 2 mM L-glutamine, 100 U/mL penicillin and 100 μg/mL streptomycin (all reagents were from EuroClone S.p.A., Milan, Italy; GE Healthcare Life Sciences, Logan, UT, USA). All cell lines were cultured in a humidified atmosphere at 37 °C in 5% CO₂.

Cells with a narrow range of passage number (4 ± 6) were tested for Mycoplasma contamination and used for all experiments. After obtaining the cells, the first passage carried out was assigned passage number 1 [35].