Targeting of Survivin Inhibits Neuroblastoma Cell Proliferation

High‐riskneuroblastoma (NB) is an aggressive pediatric tumor which develops from the extracranial sympathetic nervous system and accounts for almost 15% of all childhood cancer‐related deaths. Despite recent advancements in therapeutic approaches, the overall long‐term survival rate for NB patients is still less than 50%. Drug‐ resistance, metastasis, tumor relapse, and drug‐related toxicities mandate the development of less toxic and more effective novel therapeutic approaches for treating NB patients. Survivin is known to be involved in controlling cell division and apoptosis and belongs to the inhibitor of apoptosis protein family. Oncogenic activation of survivin has been reported in different cancers, including NB. We hypothesized that inhibiting surviving protein by using a specific small molecule inhibitor will inhibit NB cell proliferation, induce apoptosis, and sensitize tumor cells to chemotherapies. Methods NB patient datasets were analyzed using publicly available R2 Genomic analysis and visualization platform. Different NB cell lines, either MYCN‐amplified NGP, IMR‐32, LAN‐5 or, MYCN non‐amplified SH‐SY5Y, SK‐N‐AS, CHLA‐255 were used in the present study. Cell‐Titer AQueous One Solution was used to perform cell proliferation assays as per the manufacturer's instructions. Clonogenic assays were performed using crystal violet dye. Apoptosis and cell cycle assays were performed using eBioscience Annexin V Apoptosis Detection Kit and Click‐iT EdU Alexa Fluor 488 Flow Cytometry Assay Kit respectively, using Attune NxT Flow Cytometer. In vitro tumorigenic studies were performed by using Corning 3D spheroid microplate system. All the assays were performed at least three times with replicates. Results In the present study, we analyzed genomic datasets of 1135 NB patients and found that high expression of survivin coding gene BIRC5 strongly correlates with poor overall and event‐free survival of NB patients. More aggressive tumors have significantly higher BIRC5 levels. To understand the effects of inhibiting survivin on NB growth, we used a specific small molecule inhibitor and performed cell proliferation and clonogenic assays. Results revealed that inhibition of survivin significantly inhibit NB proliferation and colony formation in all cell lines tested. Furthermore, survivin inhibition significantly induce apoptosis in NB cells and block the cell cycle progression. In vitro 3D spheroidal assays that recapitulate the in vivo tumor growth showed the survivin inhibitor significantly inhibits spheroid growth and induce apoptosis in a dose dependent manner. Conclusion Overall, our results suggest that survivin promotes the oncogenic potential of NB. Inhibition of survivin by using specific small molecule inhibitor is a novel therapeutic approach for NB. In our future efforts, we will combine the survivin inhibitor with chemotherapy drugs such as doxorubicin to develop a dual therapeutic approach for NB.