Abstract A128: Zebularine, a DNA methyltransferase inhibitor, increases apoptosis and decreases cell proliferation, cell cycle arrest and clonogenic capacity on childhood medulloblastoma cell lines.

Abstract

Abstract Medulloblastoma (MB) is the most common malignant brain tumors in childhood, accounting for 20 % of all primary pediatric intracranial tumors. Although conventional therapies can cure a large proportion of patients with medulloblastoma, the majority of survivors suffer from long-term side effects, including developmental and neurological deficits. Thus, new approaches and therapeutic drugs are needed. Epigenetic drugs such as inhibitors of DNA methyltransferases (iDNMTs) have shown antineoplastic effects in different tumors. Zebularine (ZB) is a potent inhibitor of DNA methylation and has been associated with induction of apoptosis and enhancing tumor chemo- and radiosensitivity. However, its effects on childhood MB have not been previously reported. Herein, this study shows the preliminary data from the effects of ZB on cell proliferation, cell cycle, clonogenic capacity and apoptosis of childhood MB cells. DAOY, ONS-76, UW-402 and UW-473 MB cell lines were used in all functional studies. Cell proliferation by XTT® assay, clonogenic capacity, cell cycle and apoptosis by flow cytometry using propidium iodide and anexin-V staining were performed using different doses of ZB (50-800µM). Statistical analysis was performed by one or two-way ANOVA and Bonferoni post-hoc. ZB decreased cell proliferation and clonogenic capacity in all cell lines in a time- and dose-dependent manner, respectively (P< 0.05). ZB also caused apoptotic cell death in MB cells, where the percentage of apoptotic cells significantly increased after treatment compared control (P<0.05), reaching 60% on DAOY cells. Since the dose of 200uM, the drug showed a cell cycle arrest in S-phase in UW-473 and UW-402 cell lines and in G2/M phase in ONS-76 and DAOY cells after 72h of exposure. These results indicate that ZB may be a promising drug for MB treatment and it confirms the potential of demethylating drugs in cancer treatment. Others studies and novel assays are being conducted to better understand these findings. Financial Support: FAPESP (process no. 2011/22440-7) Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A128. Citation Format: Augusto F. Andrade, Kleiton S. Borges, Veridiana K. Suazo, Angel Maurício Castro-Gamero, Rosane G. P. Queiroz, Carlos A. Scrideli, Luiz Gonzaga Tone. Zebularine, a DNA methyltransferase inhibitor, increases apoptosis and decreases cell proliferation, cell cycle arrest and clonogenic capacity on childhood medulloblastoma cell lines. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A128.