Abstract | OBJECTIVE: The aim of this study was to investigate the presence of germline mutations in the CDKN1B gene that encodes the cyclin-dependent kinase ( Cdk) inhibitor p27 in multiple endocrine neoplasia 1 (MEN1)-like Spanish index patients. The CDKN1B gene has recently been identified as a tumor susceptibility gene for MEN4, with six germline mutations reported so far in patients with a MEN-like phenotype but negative for MEN1 mutations. DESIGN AND METHODS: Fifteen Spanish index cases with MEN-like symptoms were screened for mutations in the CDKN1B gene and the mutant variant was studied functionally by transcription/translation assays in vitro and in transiently transfected HeLa cells. RESULTS: We report the identification of a heterozygous GAGA deletion in the 5'-UTR of CDKN1B, NM_004064.3:c.-32_-29del, in a patient affected by gastric carcinoid tumor and hyperparathyroidism. This deletion falls inside the region that is responsible for CDKN1B transcription and is predicted to destroy a secondary stem and loop structure that includes the GAGAGA element responsible for ribosome recruitment. Accordingly, in vitro studies of coupled transcription/translation assays and transient transfection in HeLa cells showed that the GAGA deletion in the CDKN1B 5'-UTR significantly impairs the transcription of downstream reporter luciferase (of ∼40-60%) and, possibly, the translation of the corresponding mRNA. This mutation was associated with a significant reduction in the amount of CDKN1B mRNA in peripheral blood leukocytes from the patient, as demonstrated by quantitative real-time PCR. CONCLUSIONS: Our results confirm that germline CDKN1B mutations may predispose to a human MEN4 condition and add novel evidence that alteration in the transcription/translation rate of CDKN1B mRNA might be the mechanism implicated in tumor susceptibility.
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Authors | Donatella Malanga, Silvia De Gisi, Miriam Riccardi, Marianna Scrima, Carmela De Marco, Mercedes Robledo, Giuseppe Viglietto |
Journal | European journal of endocrinology
(Eur J Endocrinol)
Vol. 166
Issue 3
Pg. 551-60
(Mar 2012)
ISSN: 1479-683X [Electronic] England |
PMID | 22129891
(Publication Type: Case Reports, Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- CDKN1B protein, human
- Cyclin-Dependent Kinase Inhibitor p27
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Topics |
- Adult
- Aged
- Base Sequence
- Cyclin-Dependent Kinase Inhibitor p27
(genetics)
- Female
- Germ-Line Mutation
(genetics)
- HeLa Cells
- Humans
- Male
- Middle Aged
- Molecular Sequence Data
- Multiple Endocrine Neoplasia Type 1
(diagnosis, genetics)
- Phenotype
- Spain
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