Genetics of Endocrine Tumours - Familial Isolated Pituitary Adenoma - FIPA
Genetics of Endocrine Tumours - Familial Isolated Pituitary Adenoma - FIPA
The research is aimed at identifying new predisposition genes for endocrine tumours. Our
 focus initially is on pituitary adenomas including growth hormone-secreting tumors
 (somatotrophinomas) and prolactin secreting tumours (prolactinomas), but we wish to extend
 work to other pituitary tumour cases/families.

 The recruitment process will be as follows.

 1. We will recruit patients from our own Endocrine outpatient clinics and inpatient wards.
 In addition we will ask colleagues in other Endocrinology Departments (or other
 specialties such as Clinical Genetics,Pathology, General Medicine ) to identify
 potentially suitable patients with endocrine & pituitary tumours from their records. We
 shall focus on patients with good evidence of inheritance of their condition: relatively
 early onset; or multiple lesions; or other affected family members. Conditions where the
 predisposing genes have been identified (principally MEN) will be excluded from study.
 Patients directly contacting us can also enter the study.

 2. The Consultant looking after the patient will contact the patient to initially inform
 him/her of the study.

 3. We will then contact the patient (generally by telephone) to discuss the study and what
 it would entail in terms of information and samples.

 4. Subject to agreement in (3), patient will receive 'Information Sheet for patients with
 pituitary tumour' and 'Consent Form' and will have blood sampling in Consultant's
 clinic.

 5. We will contact additional family members (if appropriate) after an initial approach by
 the family member already recruited to the study. The additional family members may have
 developed tumours similar to those of the proband, or may be unaffected individuals who
 provide useful information for gene identification purposes (for example, spouses may
 greatly aid the power of gene mapping by linkage. They will receive the "Information
 Sheet for family members". analysis).

 8. Archival tissue will be obtained from HTA licensed tissue banks. This is an established
 bank whose licence is primarily for diagnosis but can be used for research. 9. We will
 undertake laboratory work, such as genetic linkage analysis, candidate gene mutation
 screening and studies of loss of heterozygosity in tumours, to identify the genes
 predisposing to the condition, such as the AIP gene. In addition we would like to screen
 other genes related to the chaperon AIP molecule, such as AhR, and other genes currently
 identified (PDE4A5, survivin and Tom20 protein) or may not been identified.

 Blood samples for DNA and RNA will coded with unique ID numbers. Pituitary and other
 endocrine tumour samples will be collected at surgery and kept in liquid nitrogen or -80 C.
 They will be coded with unique ID numbers. Candidate gene sequencing will be performed in the
 Barts and the London Medical School Genome Centre.

 RNA expression studies from blood or adenoma tissue samples will be performed by RT-PCR.
 Protein expression studies will be performed by Western blotting or immunohistochemistry. The
 first gene we wish to study causes familial acromegaly, a disease resulting from a pituitary
 adenoma secreting growth hormone.

 To establish if the candidate gene is also causing possibly sporadic (not familial) cases of
 the disease, samples (blood and tissue) will be collected from patients with sporadic disease
 and will be analysed as above.
We wish to find genes which predispose to pituitary tumours, to find out how those genes work
 and to assess those genes (and similar genes) in other conditions related to the pituitary
 tumours.

 We will study the recently identified new familial pituitary adenoma gene AIP (AhR
 interacting protein) and its partner molecules for example AhR (aryl hydrocarbon receptor) in
 familial and sporadic pituitary adenoma cases.

 We have 3 main questions:

 Is the identified gene (e.g. AIP) involved in the pathogenesis of familial pituitary tumours
 (acromegaly), are there any mutations in this gene in these families? What is the function of
 the new gene in pituitary tumorigenesis? Does the new gene or its partners have a role in
 sporadic pituitary adenoma tumorigenesis?

 Pituitary tumours comprise around 15% of all intracranial neoplasms, and present with
 distinct clinical characteristics, usually in terms of local space-occupying effects, or
 secondary to tumoral hypersecretion or its consequences. Acromegaly and gigantism are due in
 more than 99% of cases to a somatotroph adenoma, which has been demonstrated to be monoclonal
 in the great majority of instances1. It has been suggested that there are 6 major features of
 oncogenesis which all need to be present in cases of cancer2, but only 3 of these (activation
 of an oncogene, inactivation of a tumour suppressor gene [TSG], inhibition of apoptosis)
 appear to be relevant to pituitary tumorigenesis; these tumours are usually benign adenomas,
 and the formation of new blood vessels and the capacity for metastasis are uncommon, although
 some way of evading senescence may be important. It has therefore been suggested that a very
 small number of mutations in oncogenes and/or TSG's may be causally responsible for pituitary
 adenomas. This makes them an excellent model for the early stages of tumorigenesis. However,
 while much has been established regarding the molecular pathology of these tumours, including
 extensive studies from our own laboratory3-7, the initiating mutation or mutations
 responsible for tumorigenesis have to date defied analysis.

 Early work established that some 30% of patients with acromegaly had one of 2 mutations of
 the alpha-subunit of the receptor-associated G protein, leading to constitutive activation,
 but it has been difficult to show that this has relevant biological consequences. We have
 identified a partial failure of the feedback regulation on somatotroph tumours, but no
 mutations of the relevant genes have been recorded6,8. We and others have also explored the
 possibility that there are somatic mutations in sporadic somatotroph tumours of genes
 identified in some hereditary syndromes associated with acromegaly (MEN-I, Carney syndrome),
 but these appear to be extremely rare9. However, we have worked in collaboration with a
 Chicago group who have been seeking to identify the gene responsible for familial acromegaly,
 a very rare dominant condition10-14. Some 46 families have been described worldwide over the
 last 40 years, and from a cohort of 8 families a region on chromosome 11q13 has been
 identified: we have sought to use data from our microarray studies15 to pinpoint the abnormal
 gene in these patients, but so far unsuccessfully. Our recent work has suggested that there
 are abnormalities of the cell cycle in pituitary adenomas, especially down-regulation of the
 cycling-dependent kinase inhibitor p27 and activation of cycling E, and that this is
 secondary to a putative abnormal growth factor receptor(s), but specific mutations of these
 receptors are absent16.

 Very recently, a Finnish group have identified a dominant gene of very low penetrance which
 appears to segregate with familial somatotroph and prolactin-secreting tumours17. This lies
 at or near position 11q13, but it remains unclear as to whether this is indeed the same gene
 identified in our families with a much more strongly penetrant condition. The gene codes for
 AIP (= aryl hydrocarbon receptor interacting protein, also known as XAP2 hepatitis B virus
 X-associated protein 2 or ARA9 = AhR (aryl hydrocarbon receptor)-activated protein 9. AIP has
 330 amino acids and has a PPIase-like domain FKBP12 and four tetratricopeptide repeats
 (TPRs), probably important for protein-protein interactions.

 AIP is a putative activating partner for the aryl hydrocarbon receptor, probably increasing
 the function of AhR. AhR has been linked to the induction of hepatic detoxifying gene
 products in response to environmental toxins such as dioxin18. However, an additional
 function appears to be regulation of the cell cycle, suppressing cyclin E and increasing
 expression of p2719. The AhR also has been shown to interact with cyclic AMP. In this latter
 instance, the interaction with cAMP appears to compete with the dioxin-dependent pathway,
 such that AhR has enhanced transport into the nucleus with transcriptional effects quite
 separate to those stimulated by dioxin and related ligands. As cAMP is an important second
 messenger in somatotroph tumours, this may be the relevant pathway underlying the apparent
 activity of AIP as a tumour suppressor.

 There is therefore a primary reason to believe that AIP may indeed function as a TSG in
 pituitary adenomas, and loss of heterozygosity for 11q13 as been seen in tumours in familial
 cases17. However, the initial Finnish data were only based on 3 families, and we now plan to
 investigate our entire cohort of families with acromegaly and prolactinomas, as well as
 further families that we are in the process of collecting. We have contacted many
 endocrinologists throughout the UK, and we have identified a small number of additional
 families. Finally, in the initial study some of the patients were apparently isolated cases
 of acromegaly, but presenting at an unusually young age, especially with gigantism. In such
 cases too mutations of the AIP gene were recorded.

 Plan of Investigation: We plan to screen all known families with a history of acromegaly
 and/or prolactinomas, as well as other pituitary tumour families to be identified in the UK,
 for mutations of the AIP gene. In addition we would like to screen other genes related to the
 chaperon AIP molecule, such as AhR, and other genes currently identified (PDE4A5, survivin
 and Tom20 protein) or may not been identified. As the data suggest that early onset,
 aggressive, seemingly sporadic cases of acromegaly or prolactinoma could also be caused by
 germline mutations, we will include patients with clinically sporadic but early-onset
 aggressive disease.

 The patients will be recruited from Endocrinology Departments from the collaborating centres
 (Barts Hospital London, Newcastle, Oxford, Stroke-on-Trent, Sheffield, Manchester, Aberdeen
 and Stroke-on-Trent).

 Blood samples will be assessed for germline DNA, RNA and protein isolated for peripheral
 lymphocytes collected in a peripheral blood sample. Affected family members will be
 identified, as well as first-degree relatives both affected and unaffected. At the same time,
 all apparent mutations or polymorphisms of AIP will be tracked in a cohort of 100 germline
 blood samples from normal volunteers for assessment of the background gene frequency in order
 to assess their relationship to disease status. Patient tumour samples will collected and RNA
 and protein expression studied.
Inclusion Criteria:

 -  Familial acromegaly or other type of pituitary tumour OR

 -  Early onset acromegaly or

 -  Sporadic pituitary tumour

 Exclusion Criteria:

 -  Do not consent