Cardiac function in mild primary hyperparathyroidism and the outcome after parathyroidectomy.

OBJECTIVE: Primary hyperparathyroidism (PHPT) is associated with cardiovascular morbidity. The extent of cardiovascular abnormalities in patients with mild-asymptomatic disease is unclear. Using sensitive echocardiographic methods, we compared cardiac structure and function in patients with mild PHPT and in healthy controls, and evaluated the changes after parathyroidectomy (PTX). METHODS: In a prospective case-control design, we studied 51 PHPT patients without any cardiovascular risk factors/diseases and 51 healthy matched controls. Cardiac structure, and systolic and diastolic function were evaluated by echocardiography and Doppler tissue imaging (DTI). Blood pressure (BP) and heart rate were measured. RESULTS: We observed no differences in systolic or diastolic function or in cardiac morphology between the PHPT patients and the age-matched healthy controls. The regional peak systolic myocardial velocities (S') measured with DTI decreased at all sites (P<0.05) after PTX (tricuspid annulus 14.23+/-1.85 to 13.48+/-1.79, septal 8.48+/-0.96 to 7.97+/-0.85, and lateral 9.61+/-2.05 to 8.87+/-1.63 cm/s, part of the mitral annulus). At baseline, systolic BP was higher in patients compared to controls (127.6+/-17.1 vs 119.6+/-12.6 mmHg, P<0.05). After PTX, both systolic (127.6+/-17.1 vs 124.6+/-16.6 mmHg, P<0.05) and diastolic (80.3+/-9.6 vs 78.4+/-8.6 mmHg, P<0.05) BP decreased. CONCLUSIONS: Our results indicate that patients with PHPT without cardiovascular risk factors have a normal global systolic and diastolic function and cardiac morphology. BP and the systolic velocities were marginally reduced after PTX, but reflected the values of the control group. Our findings warrant further investigation of the clinical and prognostic significance of these possibly disease-related inotropic effects.

Operation for primary hyperparathyroidism: the new versus the old order. A randomised controlled trial of preoperative localisation.

BACKGROUND AND AIMS: In patients with primary hyperparathyroidism (PHPT), parathyroid imaging is nowadays routinely used for the purpose to perform a focused unilateral minimally invasive operation. The outcome of this new strategy has, however, not been established in randomised trials. MATERIAL AND METHODS: Patients were randomised to either preoperative localisation with sestamibi scintigraphy and ultrasonography (group I) or no preoperative localisation (group II). In group I, a minimally invasive parathyroidectomy was performed in patients in whom both localisation studies were consistent with a single pathological gland, whereas a conventional bilateral neck exploration was performed in cases with negative localisation findings. In group II all patients underwent conventional bilateral neck exploration. Primary outcome measure was normocalcaemia at 6 months postoperatively. RESULTS: In the preoperative localisation group (group I) 23/50 (46%) of the patients could be operated on with the focused operation whereas 26/50 (52%) were operated on by bilateral neck exploration. All patients in the no localisation group (group II; n = 50) were operated on with the intended bilateral neck operation. Normocalcaemia was obtained in 96% and 94% in group I and II, respectively. Total (localisation and operative) costs were 21% higher in group I. CONCLUSIONS: Routine preoperative localisation, with the intention to perform minimally invasive parathyroidectomy, is not cost effective if concordant results of scintigraphy and ultrasonography are a prerequisite for the focused operation. Less than half of the patients were successfully managed with this strategy, at a higher cost and without obtaining a more favourable clinical outcome.

Predictors of outcome in patients with papillary thyroid carcinoma.

AIM OF THE STUDY: To evaluate prognostic factors with respect to the outcome in a consecutive series of patients with papillary thyroid carcinoma (PTC) treated at the same institution during a 20-year-period, and to evaluate further the predictive ability of outcome of the pTNM, AMES and MACIS prognostic systems in these patients. MATERIALS AND METHODS: Two hundred and twenty consecutive patients operated on for primary PTC at the Karolinska Hospital between 1980 and 1999 were examined retrospectively. Patient and tumour characteristics at the time of surgery were compared to the patients' outcomes. Univariate and multiple logistic regression analyses were used to identify independently significant prognostic factors with respect to the outcome. In addition, the classification of the patients according to the pTNM, AMES and MACIS prognostic systems were compared to the outcomes. RESULTS: At the end of the follow-up period 201 patients were still alive without disease, 6.5% had died from PTC and 2.5% were alive with persisting disease. In 16 patients, radical surgery could not be performed due to extensive tumour growth and/or distant metastases. Recurrences were detected in 14% of the patients considered as radically operated. The strongest independent predictors for local or distant recurrences and poor clinical outcome were the lack of radical surgery and increasing tumour size. In this investigation MACIS appeared to be the better system, regarding efficacy in predicting the outcome of PTC. CONCLUSION: Removal of all tumour tissue appears most important to a favorable outcome and in our patients MACIS appears the most useful prognostic system taking completeness of resection into account.

Primary hyperparathyroidism. Update on pathophysiology, clinical presentation and surgical treatment.

The most important step in calcium homeostasis is the regulation of parathyroid hormone (PTH) secretion. The discovery and characterization of the calcium sensing receptor (CaR) of the parathyroid cell has led to a better understanding not only of the physiology of the parathyroid glands, but also of the development of hyperparathyroidism. Drugs acting on CaR can now be designed to treat hyperparathyroidism and osteoporosis. The workshop on primary hyperparathyroidism held at the National Institutes of Health in 2002 has recommended new guidelines for the treatment of asymptomatic hyperparathyroidism. Controversy still exists regarding the treatment of patients with non-classical symptoms, such as weakness, fatigue and depression. Primary hyperparathyroidism as a risk factor for cardiovascular disease and mortality is also debated. Improved techniques for the preoperative localization of pathological parathyroid glands have led to a shift in surgical strategy: surgeons abandon the traditional bilateral neck exploration in favor of a more limited approach. This change of strategy has not been based on the results of prospective randomized studies and the long term results are not known.

HRPT2, encoding parafibromin, is mutated in hyperparathyroidism-jaw tumor syndrome.

We report here the identification of a gene associated with the hyperparathyroidism-jaw tumor (HPT-JT) syndrome. A single locus associated with HPT-JT (HRPT2) was previously mapped to chromosomal region 1q25-q32. We refined this region to a critical interval of 12 cM by genotyping in 26 affected kindreds. Using a positional candidate approach, we identified thirteen different heterozygous, germline, inactivating mutations in a single gene in fourteen families with HPT-JT. The proposed role of HRPT2 as a tumor suppressor was supported by mutation screening in 48 parathyroid adenomas with cystic features, which identified three somatic inactivating mutations, all located in exon 1. None of these mutations were detected in normal controls, and all were predicted to cause deficient or impaired protein function. HRPT2 is a ubiquitously expressed, evolutionarily conserved gene encoding a predicted protein of 531 amino acids, for which we propose the name parafibromin. Our findings suggest that HRPT2 is a tumor-suppressor gene, the inactivation of which is directly involved in predisposition to HPT-JT and in development of some sporadic parathyroid tumors.

Distinct target regions for chromosome 1p deletions in parathyroid adenomas and carcinomas.

Primary hyperparathyroidism is a common endocrine disease with a multifaceted genetic background, the elucidation of which has only begun. Among others, loss of the short arm of chromosome 1 and somatic inactivation of the multiple endocrine neoplasia type 1 gene (MEN1) in 11q13 represent significant alterations in the tumorigenesis. In the present study deletions of 1p were characterized and the findings were evaluated in relation to the loci of MEN1 and histone deacetylase 1 gene (HDAC1), a menin interacting partner in 1p, as well as to the clinical characteristics. Overall 1p LOH was detected in 18 of the 42 tumors analyzed (43%), and from the deletion patterns a main target interval of 40 cM was identified within 1p band 32.3-36.2. The mapping of HDAC1 centromeric of the main interval, and the lack of altered mRNA expression in tumors with LOH, suggest that HDAC1 is not the main target for 1p deletions in parathyroid tumors. Twenty-five of the 42 tumors (60%) showed alteration of either 1p, of the MEN1 locus, or both. Tumors with LOH at 11q13 had a significantly higher weight than tumors with 1p LOH. In conclusion, LOH in primary sporadic parathyroid adenomas occur frequently on the distal part of chromosome 1p and are thus clearly different from parathyroid carcinomas where the deletions are more proximally located. The findings support that the short arm of chromosome 1 harbors at least two different tumor suppressor genes involved in parathyroid tumorigenesis, the exact identification of which may provide a molecular basis for differential diagnosis of benign and malignant disease in the future.

Heterogeneous expression of receptor mRNAs in parathyroid glands of secondary hyperparathyroidism.

BACKGROUND: Secondary hyperparathyroidism (HPT) is characterized by inappropriate control of parathyroid hormone (PTH) secretion and asymmetric hyperplasia of the parathyroid glands. Receptors for calcium and vitamin D are involved in the control of secretion, as well as parathyroid cell proliferation. Defective receptor mechanisms therefore may play a role in the pathogenensis of secondary HPT. Previous studies have shown that the expression of calcium receptor (CaR), calcium-sensing receptor (CAS) and vitamin D receptor (VDR) protein, and mRNA is decreased in hyperplastic parathyroid glands of secondary HPT when compared with normal parathyroid glands. METHODS: Thirty-six hyperplastic glands from 18 patients with secondary hyperparathyroidism were analyzed with in situ hybridization in order to investigate the expression of CaR, CAS, VDR, and PTH mRNAs in the same specimens. In nine nodular parathyroid glands, it was possible to make a comparison between the expression of these mRNAs in nodular and internodular areas. RESULTS: The level of CaR was in the same order of magnitude in the hyperplastic glands and in the biopsies of normal parathyroid, whereas the levels of CAS, VDR and PTH were clearly reduced in the hyperplastic glands. There was a positive correlation between the expression of CaR and CAS (P = 0.02). Otherwise, no correlations between CaR, CAS, VDR, and PTH mRNAs were found. The expression of all four genes was highly variable as well between different glands as within individual glands. CONCLUSION: The expression of mRNAs for receptors of importance in the control of PTH secretion and parathyroid cell proliferation is heterogeneously decreased in parathyroid glands of secondary HPT. The expression pattern corroborates earlier studies in which it has been assumed that each nodule in secondary HPT is of monoclonal origin, but that the monoclonal origin of each nodule is independent.

Homozygous inactivation of the MEN1 gene as a specific somatic event in a case of secondary hyperparathyroidism.

BACKGROUND: Most patients who have been surgically treated for secondary hyperparathyroidism (HPT) harbor at least one pathological parathyroid gland with a tumor of monoclonal origin. OBJECTIVE: To elucidate the underlying genetic mechanisms behind secondary HPT, by studying a panel of such tumors for numerical alterations. METHODS: Sixteen parathyroid glands from eight patients (median age 58 years, range 31-74 years), were screened for numerical chromosomal imbalances, using comparative genomic hybridization (CGH). Mutation analysis of the multiple endocrine neoplasia type 1 gene (MEN1) was also performed by sequencing of the coding region. RESULTS: The results show that gross chromosomal alterations occur rarely in secondary HPT. In one of the three glands analyzed from one patient, a complete loss of chromosome 11 was detected. This gland also had an inactivating nonsense mutation, E469X, of the MEN1 gene. The mutation was present neither in the other two glands, nor in the constitutional tissue of the same patient, thus confirming its somatic origin. CONCLUSIONS: The relative lack of numerical chromosomal alterations would suggest that more discrete genetic alterations are responsible for the monoclonal growth in the majority of cases of secondary HPT. Furthermore, somatic inactivation of the MEN1 tumor suppressor gene contributes to the tumorigenesis in a small proportion of the cases.

In vitro release of aldosterone and cortisol in human adrenal adenomas correlates to mRNA expression of steroidogenic enzymes for genes CYP11B2 and CYP17.

Adenomas of the adrenal cortex cause different disorders depending on the main steroid synthesized and released. The aim of this research is to increase our understanding of the pathophysiology of steroidogenesis in adrenocortical disorders by comparing the release of steroids from adrenocortical adenomas in vitro with the messenger RNA (mRNA) expression of steroid synthesizing enzymes. Fourteen patients with adrenal tumors were included in the present study; nine were diagnosed with primary aldosteronism and three with Cushing's syndrome. Two patients had an adrenal tumor discovered on computed tomography (CT) during workup for an unrelated disease. Serum cortisol, plasma aldosterone, and urinary catecholamines were normal. Tissue was taken for in vitro steroid release, and aldosterone and cortisol in the medium after a 1-hour incubation were determined. Oligonucleotide probes with sequences complementary to mRNAs encoding for the steroid synthesizing enzymes 11 beta-hydroxylase (CYP11B1), 18-hydroxylase (CYP11B2), 17 alpha-hydroxylase (CYP17), and 21-hydroxylase (CYP21) were synthesized (Genset, Paris, France) and in situ hybridization was performed. Moderate expression of CYP11B2 and low expression of CYP11B1 were seen in the zona glomerulosa. The zona fasciculata of the control adrenals expressed a high signal of CYP11B1, whereas the expression of CYP11B2 was very low. There was considerable variation in aldosterone release from the aldosteronomas, whereas the tumors from the Cushing patients showed no detectable release of aldosterone. In contrast, tumors from patients with primary aldosteronism, Cushing's syndrome, and no hyperfunction all had the ability to synthesize and release cortisol in vitro. The highest cortisol release was found in tumors from patients with Cushing's syndrome, but also the nonhyperfunctioning tumors and some of the aldosteronomas released significant amounts of cortisol. The two patients with highest release of aldosterone in vitro showed the highest expression of CYP11B2 and the lowest expression of CYP11B1 and CYP17. The remaining aldosteronomas had low expression of CYP11B2, similar to the two other groups. Expression of CYP11B1 was high as expected in the Cushing adenomas, but also the two nonhyperfunctioning tumors and some of the aldosteronomas showed a moderate expression. Adenomas from Cushing's syndrome, nonhyperfunctioning adenomas, and some of the aldosterone-producing adenomas had moderate to high expression of CYP17. This paper presents new means for functional characterization of adrenocortical tumors. Diagnosis of an aldosteronoma is often difficult, and with the advent of these methods it is possible to determine the functional capacity of a tumor, once it is removed. This is of special interest if the patient remains hypertensive postoperatively, and it is not clear whether the patient indeed had a functioning tumor.

[Hereditary thyroid cancer can be cured by prophylactic surgery]. / Arftlig tyreoideacancer kan botas med profylaktisk kirurgi.

Multiple endocrine neoplasia type 2 (MEN 2) is a rare syndrome in which the consequences for the patient and family members are considerable. Mutation analysis of the RET proto-oncogene is crucial for decision-making regarding each patient. Today, carriers of MEN 2 mutations should be offered prophylactic thyroidectomy with the potential to eliminate the risk for potentially lethal medullary thyroid carcinoma (MTC). Here, we present the first Swedish experience of such operations performed mainly on the basis of genetic analysis. Twenty patients underwent total thyroidectomy at a mean age of 13.5 (6-43) years. In all cases, either manifest MTC (n = 11) or C-cell hyperplasia was found. So far, no patient has any sign of recurrence or developmental insufficiency at 1-5 years follow-up. As the medical and ethical problems in this group of patients are substantial, and as the operations are performed in otherwise healthy children, they should be treated at centers with adequate multidisciplinary expertise and competence.

Expression of cellular retinol- and retinoic acid-binding proteins in normal and pathologic human parathyroid glands.

We have previously reported data establishing the human parathyroid gland as a target organ for vitamin A. In the present study, we identified Ito-like cells in parathyroid glands, suggesting local stores of vitamin A. Furthermore, we used immunohistochemistry to investigate the expression of the cellular retinol-binding protein type 1 and the cellular retinoic acid-binding protein type 1 (CRABP I) in histologically normal glands, in remnants of "normal" glandular tissue adjacent to adenoma, in adenomas, and in hyperplastic glands of chief cell type. All normal and abnormal glands displayed immunoreactivity to the two antibodies. CRABP I appeared in the cytoplasm, cell membranes, and nuclear membranes in normal glands, but only exceptionally in the nuclear membranes in abnormal glands. Since retinoic acid inhibits the secretion of parathyroid hormone and CRABP I is thought to play a key role in regulating the amount of retinoic acid available to interact with specific nuclear receptors, these data may suggest impaired transport of retinoic acid to cell nuclei, thus contributing to the development of hyperparathyroidism.

Patterns of chromosomal imbalances in parathyroid carcinomas.

In this study we have characterized chromosomal imbalances in a panel of 29 parathyroid carcinomas using comparative genomic hybridization (CGH). The most frequently detected imbalances were losses of 1p and 13q that were seen in >40% of the cases. The commonly occurring regions of loss were assigned to 1p21-p22 (41%), 13q14-q31 (41%), 9p21-pter (28%), 6q22-q24 (24%), and 4q24 (21%), whereas gains preferentially involved 19p (45%), Xc-q13 (28%), 9q33-qter (24%), 1q31-q32 (21%) and 16p (21%). The distribution of CGH alterations supports the idea of a progression of genetic events in the development of parathyroid carcinoma, where gains of Xq and 1q would represent relatively early events that are followed by loss of 13q, 9p, and 1p, and by gain of 19p. A sex-dependent distribution was also evident for two of the common alterations with preferential gain of 1q in female cases and of Xq in male cases. When the CGH profiles for the 29 carcinomas were compared with our previously published results for sporadic parathyroid adenomas, highly significant differences were revealed. Loss of 1p, 4q, and 13q as well as gains of 1q, 9q, 16p, 19p and Xq were significantly more common in the carcinomas than in the adenomas. In contrast, loss of the 11q13 region, which is the most common CGH abnormality in sporadic adenomas, was not detected in any of the carcinomas. Taken together, the findings identify several candidate locations for tumor suppressor genes and oncogenes that are potentially involved in parathyroid carcinogenesis.

Balanced translocation (3;7)(p25;q34): another mechanism of tumorigenesis in follicular thyroid carcinoma?

Alterations of 3p are the most frequently observed changes in follicular thyroid carcinomas. Loss of 3p25-pter has been speculated to be a critical event in the malignant transformation of a subset of thyroid follicular neoplasms. The present report describes a minimally invasive follicular thyroid carcinoma (FTC) with a balanced t(3;7)(p25;q34) and dic(15;22)(p11;p11) as the only abnormalities. The alterations were present in all metaphases analyzed and were demonstrated by G-banding, spectral karyotyping (SKY), and fluorescence in situ hybridization (FISH). This study represents the second case of FTC where 3p25 is involved in a balanced translocation. The findings support the existence of a gene locus in this region which is involved in the tumorigenesis of thyroid carcinoma.

Expression of matrix metalloproteinase gelatinase A messenger ribonucleic acid in parathyroid carcinomas.

BACKGROUND: The incidence of parathyroid cancer in patients with hyperparathyroidism is less than 1%. However, these few cases cause diagnostic problems in the absence of clear-cut invasion of adjacent organs or metastasis. New markers are needed to increase diagnostic accuracy. METHODS: Thirty-one parathyroid tumors from patients with primary hyperparathyroidism were collected worldwide. Eighteen tumors were classified as unequivocal cancers, whereas 13 tumors were considered equivocal because of a lack of infiltrative growth or evidence of recurrence. Paraffin sections were hybridized with a 35S-labeled riboprobe complementary to gelatinase A mRNA, dipped in photographic emulsion, developed, counterstained, and then evaluated by light- and dark-field microscopy. RESULTS: Fourteen of the 18 unequivocal parathyroid cancers expressed gelatinase A, as compared with the equivocal tumors, of which only 4 of 13 showed expression. The strongest hybridization signal was seen in stromal cells at the tumor border, most likely fibroblasts and macrophages. No expression was detected in tumor cells. CONCLUSIONS: Invasive growth of many tumors is facilitated by proteolytic enzymes, such as gelatinase A. The presence of gelatinase A mRNA in parathyroid tumors strengthens the suspicion of malignancy but cannot be used as a definitive marker of malignancy.

Alternative genetic pathways in parathyroid tumorigenesis.

In this study 44 parathyroid tumors from 26 sporadic cases, 10 cases previously given irradiation to the neck, and 8 familial cases were screened for sequence copy number alterations by comparative genomic hybridization. In the sporadic adenomas, commonly occurring minimal regions of loss could be defined to chromosome 11 (38%), 15q15-qter (27%), and 1p34-pter (19%), whereas gains preferentially involved 19p13.2-pter (15%) and 7pter-qter (12%). Multiple aberrations were found in sporadic tumors with a somatic mutation and/or loss of heterozygosity of the MEN1 gene. The irradiation-associated tumors also showed multiple comparative genomic hybridization alterations and frequent losses of 11q (50%), and subsequent analysis of the MEN1 gene demonstrated mutations in 4 of 8 cases (50%). The adenomas from familial cases showed few alterations, and in 3 of these tumors a gain of 19p13.2-pter was seen as the only aberration. In this study numerical copy number alterations were frequently detected in sporadic and irradiation-associated parathyroid adenomas, although these tumors are benign. The majority of these alterations were found in tumors with confirmed involvement of the MEN1 gene locus in agreement with a role of the MEN1 gene in genomic stability. Furthermore, the frequent occurrence of MEN1 mutations (50%) in irradiation-associated parathyroid tumors suggests that inactivation of the MEN1 gene is an important genetic alteration involved in the development of parathyroid tumors in postirradiation patients.

No overrepresentation of congenital adrenal hyperplasia in patients with adrenocortical tumours.

OBJECTIVE: The development and progression of sporadic adrenocortical tumours are poorly understood. In autopsy studies adrenocortical tumours are found in between 2 and 9% of the general population. In congenital adrenal hyperplasia (CAH), decreased production of cortisol leads to increased secretion of ACTH from the pituitary, resulting in hyperplasia of the adrenals. More than 95% of all cases of CAH are due to steroid 21-hydroxylase deficiency, resulting from mutations in the CYP21 gene. In subjects homozygous and heterozygous for CYP21 mutations, adrenocortical tumours have been found in a high frequency compared to the general population, suggesting that chronic ACTH stimulation may play a role in the development of this tumour form. In order to test whether mild undiagnosed CAH is a common predisposing factor, we screened 27 patients with sporadic adrenocortical tumours for CYP21 mutations. DESIGN: A retrospective study. PATIENTS: We screened 27 patients with sporadic adrenocortical tumours, representing both benign and malignant as well as hormonally active and silent lesions. MEASUREMENTS: Mutation analyses of the CYP21 gene was performed by allele-specific PCR on high molecular weight DNA. The method used detects the nine CYP21 mutations that are responsible for 95% of all disease-causing alleles in CAH. RESULTS: No mutations were detected in any of the 23 DNA samples that were prepared from leucocytes. In 4 cases where no leucocyte DNA was available, tumour tissue was analysed. In one of these tumours, two CYP21 mutations, V281 L and L307insT, were found in heterozygous form. CONCLUSION: Our data indicate that mild undiagnosed congenital adrenal hyperplasia is not a common underlying factor predisposing to adrenocortical tumours, at least not in the Swedish population.

[A Scandinavian multicenter study will investigate the question: surgery or not in mild primary hyperparathyroidism?]. / Skandinavisk multicenterstudie skall utreda frågan: kirurgi eller ej vid lindrig primär hyperparatyreoidism?

Primary hyperparathyroidism is a common endocrine disease particularly prevalent among elderly women. A majority of these patients diagnosed today are mildly hypercalcaemic, and many seem to lack manifest symptoms or complications. In such cases, conservative follow-up rather than parathyroid surgery may be suggested. However, long-term follow-up may entail costly investigations and be difficult to accomplish. Moreover, conservative follow-up is associated with a risk of subsequent complications or even premature death due to cardiovascular disorders. A Scandinavian multicentre study has been initiated to assess survival, morbidity and quality of life in surgically vs. conservatively treated patients.

Genotyping of adrenocortical tumors: very frequent deletions of the MEN1 locus in 11q13 and of a 1-centimorgan region in 2p16.

To identify chromosomal regions that may contain loci for tumor suppressor genes involved in adrenocortical tumor development, a panel of 60 tumors (39 carcinomas and 21 adenomas) were screened for loss of heterozygosity. Although the vast majority of loss of heterozygosity (LOH) were detected in the carcinomas and involved chromosomes 2, 4, 11, and 18, only few were found in the adenomas. Therefore, 2 loci that harbor the familial cancer syndromes Carney complex in 2p16 and the multiple endocrine neoplasia type 1 gene in 11q13 were further studied in 27 (13 carcinomas and 14 adenomas) of the 60 tumors. Detailed analysis of the 2p16 region mapped a minimal area of overlapping deletions to a 1-centimorgan region, which is separate from the Carney complex locus. LOH for a microsatellite marker (PYGM), very close to the MEN1 gene, was detected in all 8 informative carcinomas (100%) and in 2 of 14 adenomas. Of the 27 cases analyzed in detail, 13 cases (11 carcinomas and 2 adenomas) showed LOH on chromosome 11 and was therefore selected for MEN1 gene mutation analysis. In 6 cases a common polymorphism (Asp418Asp) was found, but no mutation was detected. In conclusion, our data indicate the existence of tumor suppressor genes at multiple chromosomal locations, whose inactivations are involved in the development of adrenocortical carcinomas. Loss of genetic material from 2p16 was strongly associated with the malignant phenotype, as it was seen in almost all carcinomas but not in any of the adenomas. LOH in 11q13 also occurred frequently in the carcinomas, but was not associated with a MEN1 mutation, suggesting the involvement of a different tumor suppressor gene on this chromosome.

Gelatinase A and membrane-type 1 matrix metalloproteinase mRNA: expressed in adrenocortical cancers but not in adenomas.

In an attempt to understand the mechanism behind the invasion and metastasis in adrenocortical cancer we performed mRNA in situ hybridization on 30 tumors for three matrix metalloproteinases (MMPs): gelatinase A, membrane type 1 matrix metalloproteinase (MT1-MMP), and collagenase-3. All are known to participate in the invasion and metastasis of other tumor forms by degrading the extracellular matrix. Thirteen of sixteen cancers, but only one of fourteen benign lesions showed expression of gelatinase A, which was localized in stromal cells. MT1-MMP is thought to assist in tumor invasion and metastasis by activating the zymogen gelatinase A. Of 14 malignant tumors analyzed, 12 showed MT1-MMP mRNA expression, which in 7 cases was detected in both neoplastic and stromal cells. The benign tumors showed MT1-MMP expression in only 3 of 11 cases, and it was restricted to tumor cells. Fourteen tumors (11 cancers, 3 adenomas) were also analyzed for collagenase-3 mRNA, but no expression was detected. In conclusion, our data show that gelatinase A mRNA is expressed in most malignant adrenocortical tumors but not in the benign tumors. Gelatinase A mRNA expression is restricted to stromal cells, whereas its activator, MT1-MMP, is expressed in both stromal and neoplastic cells. Inhibition of gelatinase A and other proteinases may in the future become important as a form of cancer treatment.