Medulloblastoma (MBL), the most common malignant pediatric brain tumor, is incurable in about one-third of patients and can lead to long-term disabilities despite current multimodal treatments. The purpose of this study was to demonstrate in vitro biological effects of neurotrophins-3 (NT-3) on MBL cells and to evaluate the growth-inhibitory effect of neurotrophin-3 (NT-3)-secreting stem cells on tumor cells. We confirmed by western blotting that D283-MED cells express tyrosine kinase C, a specific receptor for NT-3. Analyzing the biological effects of NT-3 on MBL cells, we evaluated autophagy, apoptosis, senescence, and differentiation of tumor cells with NT-3. The NT-3 induced a concentration-dependent increase in apoptosis in the tumor cell line (P < 0.001). The high concentrations of NT-3 increased the expression of class III β-tubulin (P < 0.001) and decreased the expression of Nestin (P < 0.05). NT-3-secreting stem cells were produced by nucleofecting pIRES2.EGFP-NT3 into human adipose tissue-derived mesenchymal stem cells (hAT-MSCs) and their tropic property toward MBL cells was confirmed by migration assay. Double-layered co-culture experiments with the NT-3-secreting hAT-MSCs and D283-MED MBL cells were performed, and NT-3-induced cell death was studied by 3-(4,5-dimethylathiazol-2-yl)-2,5-dephenyl-tetrazolium bromide (MTT) assay. Consequently, the high concentrations of NT-3-secreting hAT-MSCs significantly (P < 0.05) increased the death of D283-MED cells in vitro. The present study demonstrated that both apoptotic cell death and neuronal differentiation of tumor cells were the mechanisms of growth-inhibitory effect of NT-3-secreting hAT-MSCs on MBL cell line.

Medulloblastoma (MBL), the most common malignant pediatric brain tumor, is incurable in about one-third of patients and can lead to long-term disabilities despite current multimodal treatments. We evaluate the in vitro, growth-inhibitory effect of neurotrophin-3 (NT-3)-secreting stem cells on an MBL cell line and propose that this cell therapy may have therapeutic effects for MBL. NT-3-secreting stem cells were produced by nucleofecting pIRES2.EGFP-NT3 into human adipose tissue-derived mesenchymal stem cells (hAT-MSCs). Double-layered co-culture experiments with the NT-3-secreting hAT-MSCs and D283-MED MBL cells were performed, and NT-3-induced apoptosis was studied by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) test. The growth-inhibitory effects of these stem cells on human MBL in vitro were confirmed by 3-(4, 5-dimethylathiazol-2-yl)-2, 5-dephenyl-tetrazolium bromide (MTT) assay. We confirmed by western blotting that D283-MED cells express tyrosine kinase C, a specific receptor for NT-3, and we showed by fluorescence microscopy and RT-PCR that transfected hAT-MSCs express NT-3. The double-layered co-culture of D283-MED with NT-3-secreting hAT-MSCs induced a concentration-dependent increase in apoptosis in the tumor cell line. Consequently, the high concentrations of NT-3-secreting hAT-MSCs significantly (P &lt; 0.001) increased the death of D283-MED cells in vitro. The present studies demonstrate the potential of NT-3-secreting hAT-MSCs as an effective therapeutic cell therapy for human MBL in vitro, but in vivo experiments and clinical studies will be required in the future. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3450. doi:10.1158/1538-7445.AM2011-3450