Triptolide therapy for neuroblastoma decreases cell viability in vitro and inhibits tumor growth in vivo.
BACKGROUND
Heat shock protein (Hsp)-70 is overexpressed in several human malignancies, and its inhibition has been shown to kill cancer cells. Our objectives were to assess the effectiveness of triptolide, an Hsp-70 inhibitor, in treating neuroblastoma in vitro and in vivo, and to measure the associated effects on Hsp-70 levels and apoptosis markers.


METHODS
After exposing N2a and SKNSH cell lines to triptolide, cell viability was assessed. Caspase-3 and -9 activities were measured and annexin staining performed to determine if cell death occurred via apoptosis. Hsp-70 protein and mRNA levels were determined using Western blot and real-time polymerase chain reaction. In an orthotopic tumor model, mice received daily triptolide injections and were humanely killed at study completion with tumor measurement.


RESULTS
Triptolide treatment resulted in dose- and time-dependent N2a cell death and dose-dependent SKNSH killing. Triptolide exposure was associated with dose-dependent increases in caspase activity and annexin staining. Triptolide decreased Hsp-70 protein and mRNA levels in a dose-dependent fashion. Mice receiving triptolide therapy had significantly smaller tumors than controls.


CONCLUSIONS
Triptolide therapy decreased neuroblastoma cell viability in vitro and inhibited tumor growth in vivo. Our studies suggest that triptolide killed cells via apoptosis and in association with inhibition of Hsp-70 expression. Triptolide may provide a novel therapy for neuroblastoma.
Antonoff
Mara B
MB
Department of Surgery, University of Minnesota, Minneapolis, MN 55455., USA. rose0437@umn.edu
Chugh
Rohit
R
Borja-Cacho
Daniel
D
Dudeja
Vikas
V
Clawson
Kimberly A
KA
Skube
Steven J
SJ
Sorenson
Brent S
BS
Saltzman
Daniel A
DA
Vickers
Selwyn M
SM
Saluja
Ashok K
AK
D000818:Animals; D017304:Annexin A5 / Q000378:metabolism; D018906:Antineoplastic Agents, Alkylating / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004224:Diterpenes / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D004852:Epoxy Compounds / Q000627:therapeutic use; D005260:Female; D018840:HSP70 Heat-Shock Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D051379:Mice; D009368:Neoplasm Transplantation; D009447:Neuroblastoma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D010616:Phenanthrenes / Q000627:therapeutic use*; D012333:RNA, Messenger / Q000378:metabolism; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays
D017304:Annexin A5; D018906:Antineoplastic Agents, Alkylating; D004224:Diterpenes; D004852:Epoxy Compounds; D018840:HSP70 Heat-Shock Proteins; D010616:Phenanthrenes; D012333:RNA, Messenger; C001899:triptolide; D053148:Caspase 3; D053453:Caspase 9