Evaluation of CDKN2C/p18, CDKN1B/p27, and CDKN2B/p15 mRNA expression and CpG methylation status in sporadic and MEN1-associated pancreatic endocrine tumors
2008 (English)In: Clinical Endocrinology, ISSN 0300-0664, E-ISSN 1365-2265, Vol. 68, no 2, 271-278 p.Article in journal (Refereed) Published
Objective Menin, encoded by the multiple endocrine neoplasia type 1 (MEN1) gene at 11q13, enhances transcription of the cyclin-dependent kinase inhibitors (CDIs), CDKN2C (p18) and CDKN1B (p27) in mouse pancreatic islets, and inactivation of menin reduced CDKN2B (p15) expression in this mouse model. Here, we have compared the relative mRNA expression level and CpG methylation status of p18, p27 and p15 in 18 pancreatic endocrine tumours (PETs) with or without MEN1 gene mutations. Design Real-time quantitative PCR, DNA sequencing and pyro-sequencing methylation analysis were employed. Results The p18 gene was expressed in 15 out of the 18 analysed PETs. The expression level was within the range of the normal pancreatic tissues or higher. Of the three remaining tumours with no expression, two displayed loss of heterozygocity (LOH) at 11q13, one derived from a MEN1 patient. The p27 gene was expressed in all PETs at a level higher than the normal pancreatic tissues, except for one tumour. Promoter methylation was not detected for p18 and p27. p15 expression was undetectable in 8/18 (44%) of the PETs, and no general relations to tumour syndrome, malignancy or MEN1 gene mutations were evident. This was not due to homozygous gene deletions, but the p15 promoter was hypermethylated in two insulinomas. No mutations were found in the pl5 gene. Conclusions Expression of p15, p18 and p27 was not generally related to the MEN1 gene mutational status of the investigated 18 PETs. The p15 gene was silenced by promoter hypermethylation in two tumours. Dysregulation of menin and the CDIs are important in PET tumorigenesis, and their interrelations remain to be elucidated.
Place, publisher, year, edition, pages
2008. Vol. 68, no 2, 271-278 p.
Digestive diseases, Benign neoplasm, Genetic disease, Endocrinopathy, Endocrine tumor, Pancreatic tumor, Endocrinology, Pancreatic disease, Multiple endocrine neoplasia type I, Sporadic, Methylation, Nucleotide sequence, GC rich sequence, Gene expression, Messenger RNA, Tumor suppressor gene, KIP1 Gene, Evaluation
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:uu:diva-95507DOI: 10.1111/j.1365-2265.2007.03034.xISI: 000252319800017PubMedID: 17803708OAI: oai:DiVA.org:uu-95507DiVA: diva2:169749