TY - JOUR AB - Our previous studies showed that overexpression of secreted protein acidic and rich in cysteine (SPARC) induced autophagy-mediated apoptosis in PNET cells. In the present study, we attempted to elucidate the molecular mechanisms and signaling cascades associated with SPARC overexpression in combination with radiation therapy that eventually leads to autophagy-mediated apoptosis in neuroblastoma. SPARC expression in SK-N-AS and NB-1691 cells demonstrated the activation of caspase 3, cleavage of PARP and induction of apoptosis. The experiments to unravel the mechanisms associated with autophagy-apoptosis illustrated that SPARC overexpression triggered endoplasmic reticulum (ER) stress and thereby unfolded protein response (UPR). This was apparent with the activation of stress receptors, inositol-requiring enzyme (IRE 1α), RNA-dependent protein kinase (PKR)-like ER kinase (PERK) and BiP. This study further demonstrated the induction of transcription factor CHOP as a result of IRE-JNK activation in response to increased SPARC levels. Inhibition of ER stress and JNK activation led to inhibition of autophagy-mediated apoptosis. Further, the apparent expression of ER stress molecules among the orthotopic tumors treated by SPARC overexpression plasmids substantiated our in vitro observations. Taken together, these results illustrate the critical role of ER stress in regulating autophagy-mediated apoptosis in SPARC-overexpressed neuroblastoma cells and radiation treatment. AD - Department of Cancer Biology and Pharmacology, University of Illinois College of Medicine at Peoria, Peoria, IL 61605, USA AU - Sailaja,G.,S. AU - Bhoopathi,Praveen AU - Gorantla,Bharathi AU - Chetty,Chandramu AU - Gogineni,Venkateswara ,Rao AU - Velpula,Kiran ,Kumar AU - Gondi,Christopher ,S. AU - Rao,Jasti ,S. DA - 2013/01/01 DO - 10.3892/ijo.2012.1678 EP - 196 IS - 1 JO - Int J Oncol KW - secreted protein acidic and rich in cysteine neuroblastoma autophagy apoptosis endoplasmic reticulum stress PY - 2013 SN - 1019-6439 1791-2423 SP - 188 ST - The secreted protein acidic and rich in cysteine (SPARC) induces endoplasmic reticulum stress leading to autophagy-mediated apoptosis in neuroblastoma T2 - International Journal of Oncology TI - The secreted protein acidic and rich in cysteine (SPARC) induces endoplasmic reticulum stress leading to autophagy-mediated apoptosis in neuroblastoma UR - https://doi.org/10.3892/ijo.2012.1678 VL - 42 ER -