Abstract 2465: Spleen tyrosine kinase (SYK) in neuroblastoma tumorigenesis

Abstract Tyrosine kinases play an important role in tumorigenesis by contributing to the regulation of cell proliferation and survival, and are therefore among the most attractive drug targets. SYK is a non-receptor tyrosine kinase highly expressed in cells of hematopoietic origin where it contributes to immune receptor signaling. The role of SYK in cancer is best understood in hematological malignancies where it promotes survival, and SYK inhibition has been shown to be a promising therapeutic approach. For solid tumors the role of SYK remains double-edged, as it has been found to promote but also suppress tumor development dependent on the cancer type. Besides its role in survival signaling SYK has also been found to contribute to drug resistance in several malignancies. Neuroblastoma (NB) is a malignancy of early childhood. Although there have been great advances in the treatment of NB during the past 30 years, the prognosis for high- risk patients remains poor. In this study we have evaluated SYK as a potential drug target in NB. Examination of gene expression datasets indicated a correlation between high expression of SYK and poor prognosis in NB. Screening of NB cell lines showed that SYK mRNA was present in the majority of NB cells lines whereas the SYK protein was detected less frequently. However, SYK was detectable in NB tumor tissue using immunohistochemistry. The efficacy of different, commercially available, SYK inhibitors was evaluated by comparing the neuroblastoma cell lines SH-SY5Y (high SYK expression) and SK-N-BE(2) (low SYK expression) using a cell viability assay. While one inhibitor displayed a markedly stronger effect on the viability of SH-SY5Y cells compared to SK-N-BE(2) the effect of the other inhibitors appears to be less specific. To confirm that SYK inhibition leads to decreased cell proliferation SYK specific siRNA was used. After 48h incubation the cell viability of SH-SY5Y cells was decreased by approximately 25%. Our findings indicate that SYK may be a possible drug target in neuroblastoma. To further evaluate its potential, combination studies using SYK inhibitors and cytostatic drugs will be performed. Citation Format: Conny Tuemmler, Gianina Dumitriu, Julia Cserna, Ugo L. Moens, Per Kogner, John Inge Johnsen, Baldur Sveinbjørnsson. Spleen tyrosine kinase (SYK) in neuroblastoma tumorigenesis. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2465.