Cyclin E gene (CCNE) amplification and hCDC4 mutations in endometrial carcinoma.
Cyclin E overexpression occurs in a subset of endometrial carcinomas (ECs), but the molecular mechanisms underlying this alteration remain to be established. The present study has analysed amplification of the cyclin E gene (CCNE) and mutation in hCDC4, the gene coding for the F-box protein, which tags phosphorylated cyclin E for proteosomal degradation, to ascertain whether these alterations might be responsible for cyclin E overexpression in ECs. Cyclin E and p53 expression was studied by immunohistochemistry in eight atypical endometrial hyperplasias (AEHs), 51 endometrioid endometrial carcinomas (EECs), and 22 non-endometrioid endometrial carcinomas (NEECs). CCNE amplification was analysed by fluorescence in situ hybridization (FISH). Mutations in exons 2-11 of the hCDC4 gene were screened by PCR-SSCP-sequencing. Finally, the polymorphic marker D4S1610 was used to assess loss of heterozygosity (LOH) in the hCDC4 gene. Cyclin E overexpression was found in 26/81 (32%) cases and was associated with the histological type of the lesion, since it was not found in any AEHs but was present in 27% of EECs and 54.5% of NEECs (p=0.035). Cyclin E overexpression was associated with histological grade (p=0.011) and p53 immunostaining in EECs (p=0.033). CCNE amplification was found in 6 of 37 (16%) ECs examined. There was a significant association between CCNE amplification and the histological type of the lesion, since five (83%) of the six cases with amplification were NEECs (p=0.008). One EEC harboured an hCDC4 mutation: a CGA to CAA (Arg/Gln) change at codon 479. In addition, D4S1610 LOH was found in 7 of 23 (30%) informative cases analysed, but no correlation with cyclin E overexpression was found. However, the tumour with hCDC4 mutation also showed LOH. This is the first study demonstrating that cyclin E overexpression is associated with gene amplification in ECs, these alterations being more frequent in NEECs. Although hCDC4 exhibits a low mutation frequency in ECs overexpressing cyclin E, it seems to function as a tumour suppressor gene that is involved in endometrial carcinogenesis.
Cassia
Raúl
R
Laboratory of Breast and Gynaecological Cancer, Centro Nacional de Investigaciones Oncológicas, Madrid, Spain.
Moreno-Bueno
Gema
G
Rodríguez-Perales
Sandra
S
Hardisson
David
D
Cigudosa
Juan C
JC
Palacios
José
J
D001483:Base Sequence; D018797:Cell Cycle Proteins / Q000235:genetics*; D019927:Cyclin E / Q000235:genetics* / Q000378:metabolism; D016889:Endometrial Neoplasms / Q000235:genetics*; D005091:Exons / Q000235:genetics; D044783:F-Box Proteins / Q000235:genetics*; D000073979:F-Box-WD Repeat-Containing Protein 7; D005260:Female; D005784:Gene Amplification / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D016153:Genes, Suppressor; D016158:Genes, p53 / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D017404:In Situ Hybridization, Fluorescence / Q000379:methods; D019656:Loss of Heterozygosity / Q000235:genetics; D009154:Mutation / Q000235:genetics; D010766:Phosphorylation; D044767:Ubiquitin-Protein Ligases / Q000235:genetics*
D018797:Cell Cycle Proteins; D019927:Cyclin E; D044783:F-Box Proteins; D000073979:F-Box-WD Repeat-Containing Protein 7; C513273:FBXW7 protein, human; D044767:Ubiquitin-Protein Ligases