Sunitinib induces apoptosis and growth arrest of medulloblastoma tumor cells by inhibiting STAT3 and AKT signaling pathways.
Medulloblastomas are the most frequent malignant brain tumors in children. Sunitinib is an oral multitargeted tyrosine kinase inhibitor used in clinical trials as an antiangiogenic agent for cancer therapy. In this report, we show that sunitinib induced apoptosis and inhibited cell proliferation of both a short-term primary culture (VC312) and an established cell line (Daoy) of human medulloblastomas. Sunitinib treatment resulted in the activation of caspase-3 and cleavage of poly(ADP-ribose) polymerase and upregulation of proapoptotic genes, Bak and Bim, and inhibited the expression of survivin, an antiapoptotic protein. Sunitinib treatment also downregulated cyclin E, cyclin D2, and cyclin D3 and upregulated p21Cip1, all of which are involved in regulating cell cycle. In addition, it inhibited phosphorylation of signal transducer and activator of transcription 3 (STAT3) and AKT (protein kinase B) in the tumor cells. Dephosphorylation of STAT3 (Tyr(705)) induced by sunitinib was helped by a reduction in activities of Janus-activated kinase 2 and Src. Additionally, sodium vanadate, an inhibitor of protein tyrosine phosphatases, partially blocked the inhibition of phosphorylated STAT3 by sunitinib. Loss of phosphorylated AKT after sunitinib treatment was accompanied by decreased phosphorylation of downstream proteins glycogen synthase kinase-3beta and mammalian target of rapamycin. Expression of a constitutively activated STAT3 mutant or myristoylated AKT partially blocked the effects of sunitinib in these tumor cells. Sunitinib also inhibited the migration of medulloblastoma tumor cells in vitro. These findings suggest the potential use of sunitinib for the treatment of pediatric medulloblastomas.
Yang
Fan
F
Cancer Immunotherapeutics and Tumor Immunology, Beckman Research Institute, City of Hope Cancer Center, 1500 East Duarte Road, Duarte, CA 91010, USA.
Jove
Veronica
V
Xin
Hong
H
Hedvat
Michael
M
Van Meter
Timothy E
TE
Yu
Hua
H
D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D015536:Down-Regulation / Q000187:drug effects; D005229:Fatty Acids, Monounsaturated / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D008527:Medulloblastoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D010766:Phosphorylation / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D011758:Pyrroles / Q000494:pharmacology*; D050796:STAT3 Transcription Factor / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D000077210:Sunitinib; D014162:Transfection
D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; D005229:Fatty Acids, Monounsaturated; D007211:Indoles; D011758:Pyrroles; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D051057:Proto-Oncogene Proteins c-akt; C054211:9-tetradecenoic acid; D000077210:Sunitinib