Cyclin E gene (CCNE) amplification and hCDC4 mutations in endometrial carcinoma

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Abstract
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. Copyright © 2003 John Wiley & Sons, Ltd.
Funding Information
  • Centro Nacional de Investigaciones Oncológicas (PI0200355, SAF2001-0065)