Ellipticine

Acetonitrile 99.9% of HPLC grade was from Fisher Scientific (Lisbon, Portugal). Ellipticine was purchased from Sigma-Aldrich (St. Louis, MO, USA), as also were acetic acid, sulforhodamine B (SRB), trypan blue, trichloroacetic acid (TCA), and Tris-(hydroxymethyl)aminomethan (TRIS). Phenolic compound standards were from Extrasynthèse (Genay, France). RPMI-1640 medium, fetal bovine serum (FBS), Hank’s balanced salt solution (HBSS), l-glutamine, nonessential amino acids solution (2 mM), penicillin/streptomycin solution (100 U/mL and 100 mg/mL, respectively), and trypsin-EDTA (ethylenediaminetetraacetic acid) were from Hyclone (Logan, UT, USA). All other chemicals were of analytical purity and obtained from common suppliers. Water was treated via the purification system Milli-Q water (TGI Pure Water Systems, Greenville, SC, USA).

The UKF-NB-4 cell line, derived from bone marrow metastases of recurrent high-risk NBL, was a present of Prof. J. Cinatl, Jr. (J. W. Goethe University, Frankfurt, Germany). The SH-SY5Y cells were from ATCC (Manassas, VA, USA). Because the SH-SY5Y cell line has been reported that can be partially contaminated (http://web.expasy.org/cellosaurus/CVCL_0019), which could influence their responses to treatment, we verified them as cells of human origin (data not shown). Valproic acid sodium salt (VPA) and ellipticine were obtained from Sigma Chemical Co. (St. Louis, MO, USA). All additional chemicals utilized in the study were of analytical purity or better. Tested NBL cell lines were cultivated at 37 °C and 5% CO₂ in Iscove’s modified Dulbecco’s medium (IMDM) with 10% fetal bovine serum (both Life Technologies, Carlsbad, CA, USA). Cell lines were cultivated for at least 48 h with studied drugs as this time basically correlated with the time for two cycles of cell division [30 (link)]. Furthermore, this time is sufficient for the drugs investigated in the present work to enter the studied cells, influence cell cycle and cause apoptosis [22 (link),24 (link),25 (link),26 (link)].

Fetal bovine serum (FBS), l-glutamine, Hank’s balanced salt solution (HBSS), trypsin-EDTA (ethylenediaminetetraAcetic acid), penincillin/streptomycin solution (100 U/mL and 100 mg/mL, respectively), and RPMI-1640 were from Hyclone (Logan, UT, USA). Acetic acid, ellipticine, sulforhodamine B (SRB), trypan blue, trichloroAcetic acid (TCA) and Tris were purchased from Sigma Chemical Co. (St. Louis, MO, USA). Water was treated in a Milli-Q water purification system (TGI Pure Water Systems, Greenville, SC, USA).