Prostaglandin transporter mutations cause pachydermoperiostosis with myelofibrosis.

Pachydermoperiostosis, or primary hypertrophic osteoarthropathy (PHO), is an inherited multisystem disorder, whose features closely mimic the reactive osteoarthropathy that commonly accompanies neoplastic and inflammatory pathologies. We previously described deficiency of the prostaglandin-degrading enzyme 15-hydroxyprostaglandin dehydrogenase (HPGD) as a cause of this condition, implicating elevated circulating prostaglandin E(2) (PGE(2)) as causative of PHO, and perhaps also as the principal mediator of secondary HO. However, PHO is genetically heterogeneous. Here, we use whole-exome sequencing to identify recessive mutations of the prostaglandin transporter SLCO2A1, in individuals lacking HPGD mutations. We performed exome sequencing of four probands with severe PHO, followed by conventional mutation analysis of SLCO2A1 in nine others. Biallelic SLCO2A1 mutations were identified in 12 of the 13 families. Affected individuals had elevated urinary PGE(2), but unlike HPGD-deficient patients, also excreted considerable quantities of the PGE(2) metabolite, PGE-M. Clinical differences between the two groups were also identified, notably that SLCO2A1-deficient individuals have a high frequency of severe anemia due to myelofibrosis. These findings reinforce the key role of systemic or local prostaglandin excess as the stimulus to HO. They also suggest that the induction or maintenance of hematopoietic stem cells by prostaglandin may depend upon transporter activity.

Genetic analysis in a patient presenting with meningioma and familial isolated pituitary adenoma (FIPA) reveals selective involvement of the R81X mutation of the AIP gene in the pathogenesis of the pituitary tumor.

Familial isolated pituitary adenoma (FIPA), defined as the occurrence of at least two cases of pituitary adenoma in a family that does not exhibit features of syndromic diseases, such as Carney complex or Multiple Endocrine Neoplasia type 1 or 4, is a rare autosomal dominant disease with low penetrance. About 20 % of the families with FIPA harbor inactivating mutation in aryl hydrocarbon receptor-interacting protein gene (AIP) associated with loss of heterozygosity of the same genetic locus (11q13) in the tumor. Rarely different types of extra-pituitary tumors have been described in the setting of AIP mutation-positive FIPA. We present the case of a patient who was diagnosed with acromegaly due to the AIP mutation c.241C>T (p.R81X) at the age of 34 years, and treated by transsphenoidal surgery. At the age of 43 years she was diagnosed with a meningioma, and at age 46 had recurrence of the somatotropinoma. Genetic studies demonstrated loss of the normal allele (by sequencing and microsatellite analysis) in DNA from the pituitary adenoma but not from the meningioma, suggesting a selective involvement of AIP mutation in the pathogenesis of the pituitary adenoma, and a casual association with the meningioma. Further investigations are required to define the exact role of AIP in non-pituitary tumorigenesis.

Heterogeneous genetic background of the association of pheochromocytoma/paraganglioma and pituitary adenoma: results from a large patient cohort.

CONTEXT: Pituitary adenomas and pheochromocytomas/paragangliomas (pheo/PGL) can occur in the same patient or in the same family. Coexistence of the two diseases could be due to either a common pathogenic mechanism or a coincidence. OBJECTIVE: The objective of the investigation was to study the possible coexistence of pituitary adenoma and pheo/PGL. DESIGN: Thirty-nine cases of sporadic or familial pheo/PGL and pituitary adenomas were investigated. Known pheo/PGL genes (SDHA-D, SDHAF2, RET, VHL, TMEM127, MAX, FH) and pituitary adenoma genes (MEN1, AIP, CDKN1B) were sequenced using next generation or Sanger sequencing. Loss of heterozygosity study and pathological studies were performed on the available tumor samples. SETTING: The study was conducted at university hospitals. PATIENTS: Thirty-nine patients with sporadic of familial pituitary adenoma and pheo/PGL participated in the study. OUTCOME: Outcomes included genetic screening and clinical characteristics. RESULTS: Eleven germline mutations (five SDHB, one SDHC, one SDHD, two VHL, and two MEN1) and four variants of unknown significance (two SDHA, one SDHB, and one SDHAF2) were identified in the studied genes in our patient cohort. Tumor tissue analysis identified LOH at the SDHB locus in three pituitary adenomas and loss of heterozygosity at the MEN1 locus in two pheochromocytomas. All the pituitary adenomas of patients affected by SDHX alterations have a unique histological feature not previously described in this context. CONCLUSIONS: Mutations in the genes known to cause pheo/PGL can rarely be associated with pituitary adenomas, whereas mutation in a gene predisposing to pituitary adenomas (MEN1) can be associated with pheo/PGL. Our findings suggest that genetic testing should be considered in all patients or families with the constellation of pheo/PGL and a pituitary adenoma.

Oncogene-induced senescence in pituitary adenomas and carcinomas.

OBJECTIVE: The model of "oncogene-induced senescence" (OIS), resulting in cell-proliferation arrest, has recently been suggested as a possible explanation for the non-progression of pituitary tumours to malignancy. The aim of the study was to compare the expression of ß-galactosidase as a molecular marker of OIS, and p21/p16 as additional markers involved in mediating OIS, in pituitary adenomas, carcinomas and normal pituitary tissue. DESIGN: We performed: a) semi-quantitative immunohistochemistry (ß-galactosidase, p16, p21) in 41 pituitary adenomas [(11 GH-secreting, 9 PRL-secreting, 10 ACTH-secreting, 11 non-functioning (NFPAs)], 6 carcinomas (3 multihormonal: PRL/ACTH/GH, PRL/ACTH, PRL/GH/FSH; 1 non-functioning; 2 ACTH-secreting) and 7 normal pituitary tissues; b) quantitative PCR of mRNA (p16 and p21) in 6 GH-secreting, 6 NFPAs and 6 normal pituitary tissues. RESULTS: ß-galactosidase was significantly increased in GH-secreting tumours (P=0.002), NFPAs (P=0.04), macroadenomas (P=0.03) and carcinomas (P=0.02), as compared to normal pituitary tissue. We found that p16 expression was significantly lower in all tumours (both adenomas and carcinomas) probably secondary to reduced transcription, at least for NFPAs; p21 showed a different biological behaviour, implying that p21 and p16 may play different roles in the senescence of each individual type of adenoma. CONCLUSIONS: ß-galactosidase was significantly over-expressed in GH-secreting and NFPAs, and unexpectedly also in carcinomas. We speculate that the senescence pathway, which may explain the rarity of malignant progression to carcinomas in GH-secreting and NFPAs, might not be universal but cell-type specific.