Clinical and pre-clinical studies of neuroendocrine tumours (NETs) in multiple endocrine neoplasia type 1 (MEN1), and evaluation of MEN1 gene replacement therapy for MEN1-associated NETs

Multiple endocrine neoplasia type 1 (MEN1) is a rare autosomal dominant inherited multiple cancer syndrome of neuroendocrine tissues. Tumors are caused by an inherited germinal heterozygote inactivating mutation of the MEN1 tumor suppressor gene, followed by a somatic loss of heterozygosity (LOH) of the MEN1 gene in target neuroendocrine cells, mainly at parathyroids, pancreas islets, and anterior pituitary. Over 1,500 different germline and somatic mutations of the MEN1 gene have been identified, but the syndrome is completely missing a direct genotype-phenotype correlation, thus supporting the hypothesis that exogenous and endogenous factors, other than MEN1 specific mutation, are involved in MEN1 tumorigenesis and definition of individual clinical phenotype. Epigenetic factors, such as microRNAs (miRNAs), are strongly suspected to have a role in MEN1 tumor initiation and development. Recently, a direct autoregulatory network between miR-24, MEN1 mRNA, and menin was demonstrated in parathyroids and endocrine pancreas, showing a miR-24-induced silencing of menin expression that could have a key role in initiation of tumors in MEN1-target neuroendocrine cells. Here, we review the current knowledge on the post-transcriptional regulation of MEN1 and menin expression by miR-24, and its possible direct role in MEN1 syndrome, describing the possibility and the potential approaches to target and silence this miRNA, to permit the correct expression of the wild type menin, and thereby prevent the development of cancers in the target tissues.

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Germline MEN1 mutations in sixteen Japanese families with multiple endocrine neoplasia type 1 (MEN1)

Acta Endocrinologica ◽

10.1530/eje.0.1410475 ◽

1999 ◽

pp. 475-480 ◽

Cited By ~ 28

Author(s):

N Hai ◽

N Aoki ◽

A Matsuda ◽

T Mori ◽

S Kosugi

Keyword(s):

Multiple Endocrine Neoplasia ◽

Multiple Endocrine Neoplasia Type ◽

Family Members ◽

Premature Stop Codon ◽

Germline Mutations ◽

Endocrine Tumors ◽

Men1 Gene ◽

Endocrine Neoplasia ◽

Endocrine Neoplasia Type

OBJECTIVE: Multiple endocrine neoplasia type 1 (MEN1) is a syndrome of endocrine tumors involving the parathyroids, anterior pituitary and enteropancreatic neuroendocrine tissues, and is inherited in an autosomal dominant manner. Recently, the gene responsible for this syndrome, MEN1, was positionally cloned in 11q13. We aimed to assess the significance of MEN1 gene diagnostics in families with MEN1. DESIGN: Sixteen probands of familial MEN1 and their 40 family members were subjected to the study. METHODS: Full-length sequencing of the open reading frame and exon-intron boundaries in the MEN1 gene was performed with probands of familial MEN1. Family members were examined for the identified mutation in the proband. RESULTS: We identified heterozygous germline mutations of the MEN1 gene in all of 16 Japanese MEN1 families examined, achieving the highest detectability of MEN1 mutations in familial MEN1 among studies that examined more than 10 families. Eleven kinds of the identified MEN1 germline mutations were novel. More than half were nonsense or frameshift mutations resulting in a premature stop codon (9/15; 60%), and no mutation hot spots or no apparent genotype-phenotype relationships were observed, in support of the results of other studies. We identified 40 mutant MEN1 gene carriers and 16 non-carriers in the course of the present study in those families. CONCLUSIONS: Analysis of the germline mutations in the MEN1 gene, providing significantly useful clinical information to probands and family members of MEN1, should be considered as a standard procedure and categorized as belonging to Group 1 cancer predisposition testing by the American Society of Clinical Oncology.

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Multiple endocrine neoplasia type 1 (MEN1) gene mutations in a subset of patients with sporadic and familial primary hyperparathyroidism target the coding sequence but spare the promoter region

Journal of Endocrinology ◽

10.1677/joe.0.1660001 ◽

2000 ◽

Vol 166 (1) ◽

pp. 1-9 ◽

Cited By ~ 23

Author(s):

W Karges ◽

K Jostarndt ◽

S Maier ◽

A Flemming ◽

M Weitz ◽

...

Keyword(s):

Multiple Endocrine Neoplasia ◽

Multiple Endocrine Neoplasia Type ◽

Germ Line ◽

Single Strand Conformational Polymorphism ◽

Coding Sequence ◽

Men1 Gene ◽

Endocrine Neoplasia ◽

Endocrine Neoplasia Type ◽

Germ Line Mutations

Germ line mutations of the multiple endocrine neoplasia type 1 (MEN1) tumour suppressor gene cause MEN1, a rare familial tumour syndrome associated with parathyroid hyperplasia, adenoma and hyperparathyroidism (HP). Here we investigated the role of the MEN1 gene in isolated sporadic and familial HP. Using RT-PCR single-strand conformational polymorphism screening, somatic (but not germ line) mutations of the MEN1 coding sequence were identified in 6 of 31 (19.3%) adenomas from patients with sporadic primary HP, but none in patients (n=16) with secondary HP due to chronic renal failure. MEN1 mutations were accompanied by a loss of heterozygosity (LOH) for the MEN1 locus on chromosome 11q13 in the adenomas as detected by microsatellite analysis. No DNA sequence divergence within the 5' region of the MEN1 gene, containing the putative MEN1 promoter, was detectable in HP adenomas. Clinical characteristics were not different in HP patients with or without MEN1 mutation. Heterozygous MEN1 gene polymorphisms were identified in 9.6% and 25% of patients with primary and secondary HP respectively. In a large kindred with familial isolated familial HP, MEN1 germ line mutation 249 del4 and LOH was associated with the HP phenotype and a predisposition to non-endocrine malignancies. We suggest that the bi-allelic somatic loss of MEN1 wild-type gene expression is involved in the pathogenesis of a clinically yet undefined subset of sporadic primary HP adenomas. MEN1 genotyping may further help define the familial hyperparathyroidism-MEN1 disease complex, but it seems dispensable in sporadic primary HP.

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