Targeting Histone Deacetylases (HDACs) and Wee1 for Treating High-Risk Neuroblastoma

BackgroundDespite advances in treatment regimens, patients with high-risk neuroblastoma have long-term survival rates of <40%. Wee1 inhibition in combination with CHK1 inhibition has shown promising results in neuroblastoma cells. In addition, it has been demonstrated that panobinostat can downregulate CHK1. Therefore, combination of panobinostat and MK-1775 may result in synergistic cytotoxicity against neuroblastoma cell lines. ProcedureIn vitro cytotoxicities of panobinostat and MK-1775 at clinically achievable concentrations, either alone or in combination, were evaluated in SK-N-AS, SK-N-DZ, and SK-N-BE(2) high-risk neuroblastoma cell lines using MTT assays. The mechanism of antitumor interaction was investigated using propidium iodide (PI) staining and flow cytometry analysis to determine apoptosis, as well as Western blotting to assess expression of phosphorylated CDK1/2, CHK1, and H2AX. ResultsTreatment of neuroblastoma cell lines with 500nM MK-1775 caused growth arrest and apoptosis in SK-N-DZ and SK-N-AS, while it had minimal effect on the SK-N-BE(2) cell line. The combination of panobinostat and MK-1775 resulted in synergistic antitumor interactions in all three of the cell lines tested. MK-1775 treatment in SK-N-BE(2) cells induced increased levels of p-CHK1(S345), which could be decreased by the addition of panobinostat. This was accompanied by increased DNA damage and apoptosis. ConclusionsThe combination of panobinostat and MK-1775 has synergistic antitumor activity against neuroblastoma cell lines and holds promise as a potential treatment strategy for the management of high-risk neuroblastoma patients. Pediatr Blood Cancer 2015;62:52-59. (c) 2014 Wiley Periodicals, Inc.