Abstract 3199: BKM120 is cytotoxic in neuroblastoma targeting the PI3K pathway
Authors: Pomaville Monica M. , Zhao Ping , DeCou Sarah , Nagulapally Abhinav B. , Bond Jeffrey , Saulnier Sholler Giselle L. 
Published: July 2016

Background: Neuroblastoma is the most common extracranial solid tumor found in children, accounting for approximately 15% of cancer-related deaths. Many cellular processes have been discovered to play a role in neuroblastoma's potency, including a family of lipid kinases within the phosphoinositide 3-kinase (PI3K) signaling pathway that contribute to cell survival, proliferation, and differentiation. Targeting this pathway could unveil new treatment strategies that work to specifically treat each child's unique disease. BKM120 is a novel cancer therapeutic that targets the PI3K/Akt/mTOR signaling pathway and has recently been shown to have great potential in the clinic by acting on Class IA PI3Ks. Though Class IA PI3Ks hold multiple types, BKM120 has been shown to act preferentially on PIK3CA mutant isoforms. In this study we show the inhibitory effect of BKM120 on neuroblastoma cell lines that over-express PI3KCA, suggesting a promising role in the clinic for children with this expression profile. It has also been suggested that inhibitors of the PI3K pathway exert their inhibitory effects on cancer cells by destabilizing MYCN, a protein found over-expressed in approximately one third of neuroblastoma patients that encourages malignant progression of the disease.

Methods: Neuroblastoma (NB) cell lines BE(2)-C and SMS-KCNR cells and patient lines MGT-002-13, MGT-003-08, MGT-014-11, and MGT-015-08 were used in these studies. Cell viability was measured using Calcein AM fluorescent assay at BKM120 doses 0.2uM, 0.5uM, and 1.0uM. Western blot analysis was used to measure PI3K pathway members including pAKT, p-mTOR, mTOR, and apoptosis markers including Cleaved Caspase 3, Caspase 3, PARP, and cPARP. ATP level per cell was measured using CyQuant fluorescent DNA assay combined with the Cell Titer GLO luminescent cell viability assay. IncuCyte imaging of sytox and kinetic caspase-3 reagent was used to measure apoptosis in NB cells treated with BKM120.

Results: BKM120 is cytotoxic to NB cell lines with IC50's ranging from 0.9-5.5 uM. BKM120 increases protein expression levels of Cleaved Caspase 3 and cleaved PARP by inducing apoptosis and decreases MTOR, pAKT and MYCN at increasing drug doses. BKM120 decreases ATP/cell related to glycolytic metabolism activity in NB cell lines. Increased expression of MTOR and PI3KCD correlate with increased resistance to BKM120.

Conclusion: This study indicates that BKM120 targets the MTOR/PI3K/AKT pathway and may play a role in MYCN driven tumors. In addition, BKM120 inhibits NB cell proliferation and induces caspase-mediated apoptosis in vitro in NB. Given the current lack of effective treatments and the high incidence of relapse and metastatic disease for patients, further assessment in clinical trial setting is needed to assess BKM120's therapeutic activity for children with NB.

Citation Format: Monica M. Pomaville, Ping Zhao, Sarah DeCou, Abhinav B. Nagulapally, Jeffrey Bond, Giselle L. Saulnier Sholler. BKM120 is cytotoxic in neuroblastoma targeting the PI3K pathway. [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 3199.