Cyclin D1 is overexpressed in atypical teratoid/rhabdoid tumor with hSNF5/INI1 gene inactivation.
OBJECTIVE
Although atypical teratoid/rhabdoid tumor (AT/RT) is known to generate through inactivation of the hSNF5/INI1 gene on chromosome 22q, the downstream molecular mechanism remains unclear. We histologically and molecularly reviewed our pediatric brain tumors for unrecognized AT/RTs and evaluated the role of cyclin D1, a potential molecular target of hSNF5/INI1.


METHODS
We analyzed 16 tumors under three years of age: seven medulloblastomas, three anaplastic ependymomas (E IIIs), two each of supratentorial primitive neuroectodermal tumors (sPNETs) and choroid plexus carcinomas (CPCs), and one each of neuroblastoma and pineoblastoma. Immunohistochemistry for glial fibrillary acidic protein, vimentin, epithelial membrane antigen, smooth muscle actin and cyclin D1 was performed. Polymerase chain reaction (PCR)-single-strand conformation polymorphism analysis with direct sequencing, differential PCR and microsatellite analysis were conducted for hSNF5/INI1mutation, homozygous deletion and loss of heterozygosity (LOH) on 22q, respectively. Because of the presence of rhabdoid cells and the polyimmunophenotypic features, the diagnosis was revised to AT/RT in five (31%) tumors, namely, two E IIIs and one each of medulloblastoma, CPC and pineoblastoma. Three of them harbored such hSNF5/INI1 aberrations as germline single base deletion (492/6 delC) and missense mutation (C157T) together with LOH 22q or homozygous deletion. Cyclin D1 was overexpressed in those three tumors but not in the two that lacked hSNF5/INI1 inactivation.


CONCLUSIONS
AT/RT can be misdiagnosed as a variety of tumors, including ependymoma that potentially harbors LOH 22q. Our data indicate that cyclin D1 is a target of hSNF5/INI1in primary tumors.
Department of Neurosurgery, Division of Neuroscience, Graduate School of Medical Science, Kanazawa University, 13-1 Takaramachi, 920-8641 Kanazawa, Ishikawa, Japan. fujisawa@ns.m.kanazawa-u.ac.jp
Hironori
H
Fujisawa
Koichi
K
Misaki
Yasushi
Y
Takabatake
Mitsuhiro
M
Hasegawa
Junkoh
J
Yamashita
D016543:Central Nervous System Neoplasms / Q000235:genetics* / Q000378:metabolism; D002675:Child, Preschool; D016545:Choroid Plexus Neoplasms / Q000235:genetics / Q000378:metabolism; D002868:Chromosomal Proteins, Non-Histone; D002892:Chromosomes, Human, Pair 22 / Q000235:genetics*; D019938:Cyclin D1 / Q000235:genetics / Q000378:metabolism*; D020732:Cytogenetic Analysis; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D005260:Female; D006801:Humans; D007223:Infant; D019656:Loss of Heterozygosity; D008297:Male; D008527:Medulloblastoma / Q000235:genetics / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D009447:Neuroblastoma / Q000235:genetics / Q000378:metabolism; D010871:Pinealoma / Q000235:genetics / Q000378:metabolism; D020641:Polymorphism, Single Nucleotide; D018335:Rhabdoid Tumor / Q000235:genetics* / Q000378:metabolism; D000071796:SMARCB1 Protein; D013724:Teratoma / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D000071796:SMARCB1 Protein; C513266:SMARCB1 protein, human; D014157:Transcription Factors; D019938:Cyclin D1