Association between the p27 rs2066827 variant and tumor multiplicity in patients harboring MEN1 germline mutations.

OBJECTIVE: To date, no evidence of robust genotype-phenotype correlation or disease modifiers for multiple endocrine neoplasia type 1 (MEN1) syndrome has been described, leaving the highly variable clinical presentation of patients unaccounted for. DESIGN: As the CDKN1B (p27) gene causes MEN4 syndrome and it is transcriptionally regulated by the product of the MEN1 gene (menin), we sought to analyze whether p27 influences the phenotype of MEN1-mutated patients. The cohort consisted of 100 patients carrying germline MEN1 gene mutations and 855 population-matched control individuals. METHODS: Genotyping of the coding p27 c.326T>G (V109G) variant was performed by sequencing and restriction site digestion, and the genotypes were associated with clinical parameters by calculating odds ratios (ORs) and their 95% CIs using logistic regression. RESULTS: There were significant differences in p27 V109G allele frequencies between controls and MEN1-mutated patients (OR=2.55, P=0.019, CI=1.013-5.76). Among patients who are ≥30 years old carrying truncating MEN1 mutations, the T allele was strongly associated with susceptibility to tumors in multiple glands (three to four glands affected vs one to two glands affected; OR=18.33; P=0.002, CI=2.88-16.41). This finding remained significant after the Bonferroni's multiple testing correction, indicating a robust association. No correlations were observed with the development of MEN1-related tumors such as hyperparathyroidism, pituitary adenomas, and enteropancreatic and adrenocortical tumors. CONCLUSIONS: Our study suggests that the p27 tumor suppressor gene acts as a disease modifier for the MEN1 syndrome associated with MEN1 germline mutations. If confirmed in independent patient cohorts, this finding could facilitate the management of this clinically complex disease.

p27 variant and corticotropinoma susceptibility: a genetic and in vitro study.

Germline mutations in p27(kip1) are associated with increased susceptibility to multiple endocrine neoplasias (MEN) both in rats and humans; however, the potential role of common polymorphisms of this gene in endocrine tumor susceptibility and tumorigenesis remains mostly unrecognized. To assess the risk associated with polymorphism rs2066827 (p27-V109G), we genotyped a large cohort of Brazilian patients with sporadic endocrine tumors (pituitary adenomas, n=252; pheochromocytomas, n=125; medullary thyroid carcinoma, n=51; and parathyroid adenomas, n=19) and 885 population-matched healthy controls and determined the odds ratios and 95% CIs. Significant associations were found for the group of patients with pituitary adenomas (P=0.01), particularly for those with ACTH-secreting pituitary adenomas (P=0.005). In contrast, no association was found with GH-secreting pituitary tumors alone or with the sporadic counterpart of MEN2-component neoplasias. Our in vitro analyses revealed increased colony formation and cell growth rate for an AtT20 corticotropin mouse cell line overexpressing the p27-V109G variant compared with cells transfected with the WT p27. However, the genotypic effects in genetic and in vitro approaches were divergent. In accordance with our genetic data showing specificity for ACTH-secreting pituitary tissues, the overexpression of p27-V109G in a GH3 somatotropin rat cell line resulted in no difference compared with the WT. Pituitary tumors are one of the major clinical components of syndromes associated with the p27 pathogenic mutations MENX and MEN4. Our genetic and in vitro data indicate that the common polymorphism rs2066827 may play a role in corticotropinoma susceptibility and tumorigenesis through a molecular mechanism not fully understood thus far.

Penetrance of functioning and nonfunctioning pancreatic neuroendocrine tumors in multiple endocrine neoplasia type 1 in the second decade of life.

CONTEXT: Data are scarce on the penetrance of multiple endocrine neoplasia type 1 (MEN1)-related nonfunctioning pancreatic neuroendocrine tumors (NF-PETs) and insulinomas in young MEN1 patients. A potential positive correlation between tumor size and malignancy (2-3 cm, 18%; >3 cm, 43%) has greatly influenced the management of MEN1 adults with NF-PETs. OBJECTIVE: The aim of the study was to estimate the penetrance of NF-PETs, insulinomas, and gastrinomas in young MEN1 carriers. DESIGN: The data were obtained from a screening program (1996-2012) involving 113 MEN1 patients in a tertiary academic reference center. PATIENTS: Nineteen MEN1 patients (aged 12-20 y; 16 patients aged 15-20 y and 3 patients aged 12-14 y) were screened for NF-PETs, insulinomas, and gastrinomas. METHODS: Magnetic resonance imaging/computed tomography and endoscopic ultrasound (EUS) were performed on 10 MEN1 carriers, magnetic resonance imaging/computed tomography was performed on five patients, and four other patients underwent an EUS. RESULTS: The overall penetrance of PETs during the second decade of life was 42% (8 of 19). All eight PET patients had NF-PETs, and half of those tumors were multicentric. One-fifth of the screened patients (21%; 4 of 19) harbored at least one large tumor (>2.0 cm). Insulinoma was detected in two NF-PET patients (11%) at the initial screening; gastrinoma was not present in any cases. Six of the 11 (54%) screened patients aged 15-20 years who underwent an EUS had NF-PETs. Potential false-positive EUS results were excluded based on EUS-guided biopsy results, the reproducibility of the NF-PET findings, or the observation of increased tumor size during follow-up. Distal pancreatectomy and the nodule enucleation of pancreatic head tumors were conducted on three patients with large tumors (>2.0 cm; T2N0M0) that were classified as grade 1 neuroendocrine tumors (Ki-67<2%). CONCLUSIONS: Our data demonstrated high penetrance of NF-PETs in 15- to 20-year-old MEN1 patients. The high percentage of the patients presenting consensus criteria for surgery for NF-PET alone or NF-PET/insulinoma suggests a potential benefit for the periodic surveillance of these tumors in this age group.