Phosphatidylinositol 3-kinase inhibition down-regulates survivin and facilitates TRAIL-mediated apoptosis in neuroblastomas.
OBJECTIVE
Recent findings have correlated neuroblastoma development with aberration of apoptosis. In particular, increased levels of survivin, a member of the inhibitor of apoptosis protein (IAP) family, have been associated with increased resistance to apoptosis in neuroblastomas. The purpose of this study was to determine whether the phosphatidylinositol 3-kinase (PI3K)/Akt pathway can alter the expression of survivin and facilitate tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis in neuroblastoma cells.


METHODS
Human neuroblastoma cells (SK-N-SH, BE[2]C, LAN-1 and IMR-32) were treated with LY294002 or wortmannin, inhibitors of PI3K, for 24 hours. Transient transfection of a dominant negative PI3K expression plasmid, pCGNN-Deltap85, was performed to inhibit PI3K activation. Cells were treated with TRAIL, caspase-3, or pan-caspase inhibitors. RNase protection assay was performed to assess mRNA changes in IAP family members, including survivin. Western blot analysis was performed to measure changes in the levels of procaspases and survivin. Apoptosis was assessed by a DNA fragmentation ELISA assay.


RESULTS
The authors found that survivin and cIAP1 mRNA as well as protein expression were decreased after PI3K inhibition. Combination treatment with LY294002 and TRAIL increased apoptosis of SK-N-SH cells compared with TRAIL alone; these results were further corroborated by complete inhibition of apoptosis by caspase-3 or pan-caspase inhibitor.


CONCLUSIONS
The authors report that PI3K pathway inhibition down-regulates survivin expression and enhances TRAIL-mediated apoptosis in neuroblastomas. PI3K pathway may play a crucial role in neuroblastoma cell survival; therefore, treatment with inhibitors of PI3K may provide potential novel therapeutic options.
Kim
Sunghoon
S
Department of Surgery, The University of Texas Medical Branch, Galveston, TX 77555-0536, USA.
Kang
Junghee
J
Qiao
Jingbo
J
Thomas
Robert P
RP
Evers
B Mark
BM
Chung
Dai H
DH
D000730:Androstadienes / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins; D053148:Caspase 3; D053453:Caspase 9; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism / Q000494:pharmacology; D045744:Cell Line, Tumor / Q000187:drug effects / Q000473:pathology; D002867:Chromones / Q000494:pharmacology*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D053938:DNA Fragmentation / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D005799:Genes, Dominant; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins; D008562:Membrane Glycoproteins / Q000502:physiology*; D008869:Microtubule-Associated Proteins / Q000096:biosynthesis* / Q000235:genetics; D009025:Morpholines / Q000494:pharmacology*; D009363:Neoplasm Proteins / Q000096:biosynthesis* / Q000235:genetics; D009447:Neuroblastoma / Q000378:metabolism / Q000473:pathology*; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000502:physiology*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D014176:Protein Biosynthesis; D011506:Proteins / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D012334:RNA, Neoplasm / Q000096:biosynthesis / Q000235:genetics; D000077022:Survivin; D053221:TNF-Related Apoptosis-Inducing Ligand; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*; D044767:Ubiquitin-Protein Ligases; D000077191:Wortmannin
D000730:Androstadienes; D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; D053148:Caspase 3; D053453:Caspase 9; D061945:Caspase Inhibitors; D020169:Caspases; D002867:Chromones; D015853:Cysteine Proteinase Inhibitors; D004791:Enzyme Inhibitors; D051034:Inhibitor of Apoptosis Proteins; D008562:Membrane Glycoproteins; D008869:Microtubule-Associated Proteins; D009025:Morpholines; D009363:Neoplasm Proteins; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011506:Proteins; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D000077022:Survivin; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha; D044767:Ubiquitin-Protein Ligases; D000077191:Wortmannin; C107489:BIRC5 protein, human; C505653:TNFSF10 protein, human; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C494833:BIRC2 protein, human; C505407:CASP3 protein, human; C506433:CASP9 protein, human