Multiple polymorphisms, but no mutations, in the WAF1/CIP1 gene in human brain tumours.
The cyclin kinase inhibitor WAF1/CIP1, also termed CDKN1, mediates p53-induced cell cycle arrest in response to DNA damage. This property makes it an attractive tumour-suppressor candidate for a p53-associated tumour-suppressor gene. In order to investigate the role of WAF1/CIP1 in the pathogenesis of primary human brain tumours we performed single-stranded conformation polymorphism (SSCP) analysis and direct sequencing of exon 2 of the gene in a representative series of 158 brain tumours and corresponding blood samples. In addition, all tumours were examined for mutations in exons 5-8 of the p53 gene. Analysis of WAF1/CIP1 revealed multiple polymorphisms, the most abundant being AGC-->AGA (Ser-->Arg) at codon 31 with an allele frequency of 8.5%. Less common polymorphisms included GTG-->GGG (Val-->Gly) at codon 25, GCC-->ACC (Ala-->Thr) at codon 64, CGC-->CTC (Arg-->Leu) at codon 32, GGC-->AGC (Gly-->Ser) at codon 14 and GCG-->GTG (Ala-->Val) at codon 39 each with an allele frequency of 0.3%. These polymorphisms were all located in a conserved region of exon 2. Two of the polymorphisms were also seen in a group of 157 healthy controls indicating that WAF1/CIP1 polymorphisms do not predispose to cancer. None of the tumours included in our series showed a somatic mutation in WAF1/CIP1. All samples were also analysed for loss of heterozygosity on the short arm of chromosome 6 in the region of the WAF1/CIP1 locus. Allelic loss was observed in only one patient with a glioblastoma. Mutations in the p53 gene were found in 22 of 158 tumours. No association was found between any polymorphism of the WAF1/CIP1 gene, p53 mutations and histopathological tumour type. Our data indicate that WAF1/CIP1 mutations are probably not involved in the formation of primary human brain tumours.
Koopmann
J
J
Institut für Neuropathologie, Universitätskliniken Bonn, Germany.
Maintz
D
D
Schild
S
S
Schramm
J
J
Louis
D N
DN
Wiestler
O D
OD
von Deimling
A
A
D001483:Base Sequence; D001932:Brain Neoplasms / Q000235:genetics* / Q000473:pathology; D003062:Codon; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000235:genetics*; D004252:DNA Mutational Analysis; D017353:Gene Deletion; D006801:Humans; D018895:Microsatellite Repeats; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D018807:Polymorphism, Single-Stranded Conformational
C493956:CDKN1A protein, human; D003062:Codon; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins