An epigenetic genome-wide screen identifies SPINT2 as a novel tumor suppressor gene in pediatric medulloblastoma.
Medulloblastoma (MB) is a malignant cerebellar tumor that occurs primarily in children. The hepatocyte growth factor (HGF)/MET pathway has an established role in both normal cerebellar development as well as the development and progression of human brain tumors, including MB. To identify novel tumor suppressor genes involved in MB pathogenesis, we performed an epigenome-wide screen in MB cell lines, using 5-aza-2'deoxycytidine to identify genes aberrantly silenced by promoter hypermethylation. Using this technique, we identified an inhibitor of HGF/MET signaling, serine protease inhibitor kunitz-type 2 (SPINT2/HAI-2), as a putative tumor suppressor silenced by promoter methylation in MB. In addition, based on single nucleotide polymorphism array analysis in primary MB samples, we identified hemizygous deletions targeting the SPINT2 locus in addition to gains on chromosome 7 encompassing the HGF and MET loci. SPINT2 gene expression was down-regulated and MET expression was up-regulated in 73.2% and 45.5% of tumors, respectively, by quantitative real-time PCR. SPINT2 promoter methylation was detected in 34.3% of primary MBs examined by methylation-specific PCR. SPINT2 reexpression in MB cell lines reduced proliferative capacity, anchorage independent growth, cell motility in vitro, and increased overall survival times in vivo in a xenograft model (P<0.0001). Taken together, these data support the role of SPINT2 as a putative tumor suppressor gene in MB, and further implicate dysregulation of the HGF/MET signaling pathway in the pathogenesis of MB.
Kongkham
Paul N
PN
Program in Cell Biology, Division of Neurosurgery, Arthur and Sonia Labatt Brain Tumor Research Centre, Hospital for Sick Children, and Department of Pathology, University Health Network, University of Toronto, Toronto, Ontario, Canada.
Northcott
Paul A
PA
Ra
Young Shin
YS
Nakahara
Yukiko
Y
Mainprize
Todd G
TG
Croul
Sidney E
SE
Smith
Christian A
CA
Taylor
Michael D
MD
Rutka
James T
JT
D000818:Animals; D001932:Brain Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D002448:Cell Adhesion / Q000235:genetics; D048708:Cell Growth Processes / Q000235:genetics; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics; D019175:DNA Methylation; D016147:Genes, Tumor Suppressor; D017228:Hepatocyte Growth Factor / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008297:Male; D008527:Medulloblastoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D008562:Membrane Glycoproteins / Q000235:genetics*; D051379:Mice; D008819:Mice, Nude; D020411:Oligonucleotide Array Sequence Analysis; D020641:Polymorphism, Single Nucleotide; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D019859:Proto-Oncogene Proteins c-met; D017978:Receptors, Growth Factor / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D014162:Transfection; D014183:Transplantation, Heterologous
D008562:Membrane Glycoproteins; D011518:Proto-Oncogene Proteins; D017978:Receptors, Growth Factor; C109148:SPINT2 protein, human; D017228:Hepatocyte Growth Factor; C491743:MET protein, human; D019859:Proto-Oncogene Proteins c-met