Benign Adrenocortical Tumors Research Articles

Adrenocortical cancer: pathophysiology and clinical management

Adrenocortical cancer (ACC) is a rare tumor with a poor prognosis. By contrast, benign adrenocortical tumors are frequent, underlying the importance of a correct diagnosis of malignancy of such tumors. ACC can be diagnosed by the investigation of endocrine signs of steroid excess, symptoms due to tumor growth or an adrenal incidentaloma. Hormonal investigations demonstrate in most ACC steroid oversecretion, the dominant characteristics being a co-secretion of cortisol and androgens. Imaging by CT-scan or MRI shows a large heterogeneous tumor with a low fat content. Careful pathological investigation with the assessment of the Weiss score is important for the diagnosis of malignancy. Molecular markers can also be helpful and in the future might be important for prognosis. Tumors localized to the adrenal gland (McFarlane stages 1 and 2) have a better outcome than invasive and metastatic tumors (stages 3 and 4). Tumor removal by a specialized team is crucial for treatment and should always aim at complete removal. In patients with metastatic or progressive disease, medical treatment is started with mitotane that requires a close monitoring of its blood level. Surgery is indicated when possible for local recurrence but also in some cases of metastasis. Local treatment (radiofrequency, chemoembolization, and radiation therapy) can have some indications for metastatic disease. In patients with disease progression cytotoxic chemotherapy can be used. Despite the best care, the overall prognosis of ACC is poor with a 5-year survival rate below 30% in most series. Therefore, progress in the understanding of the pathophysiology of ACC is important. Despite the rarity of ACC, significant advances have been made in the understanding of its pathogenesis the last decade. These progresses came mainly from the study of the genetics of ACC, both at the germline level in rare familial diseases, and at the somatic level by the study of molecular alterations in sporadic tumors. These advances underline the importance of genetic alterations in ACC development and point-out to various chromosomal regions (2, 11p15, 11q, 17p13) and genes (IGF-II, p53, beta-catenin, ACTH receptor). This review will summarize these advances as well as the current clinical management of ACC.

126. Evaluation of Replication Competent and Replication Incompetent Adenovirus-Mediated Toxicity in Human Adrenocortical Cells

Objectives: Experimental studies indicate that adenoviruses have a natural tropism for the adrenal gland, thus, the systemic use of adenoviral vectors might be associated with side effects due to adrenal gland infection. In this study, human ACC cells were used to assess the toxicity of replication competent adenovirus type 5 (Ad5) and replication deficient E1-/E3- adenoviral vectors. Methods: To test the susceptibility of human ACC cells (SW13 and NCI-H295R) to adenoviral infection, expression of coxsackie and adenovirus receptor(CAR) and integrins was evaluated in ACC cells as well as in normal human adrenocortical tissues and in benign and malignant adrenocortical tumor samples by quantitative real-time RT-PCR. ACC cells were infected with Ad5 and tested for virus production at different time points pi. Recombinant E1-/E3- Ad5 vector expressing green fluorescent protein (Ad5-EGFP) was used to test adenovirus infectivity by fluorescent microscopy and FACS analysis. To assess the toxicity of replication competent and replication incompetent adenoviral vectors in the adrenal gland, Ad5, Ad5-EGFP and Ad5-HSV-TK were employed. In this regard, at different time points pi, we examined the effect of adenoviral infection on gene expression profile by DNA microarray analysis and on cell growth by proliferation assay, cell cycle analysis, and apoptosis test. The influence of adenoviral infection on steroid hormone production was also analyzed. Results: CAR expression was demonstrated in ACC cells and in normal and neoplastic adrenocortical tissues. Both ACC cells demonstrated productive Ad5 replication and efficient Ad5-EGFP transduction. Time- and dose-dependent induction of cell death was found only in Ad5-infected ACC cells, whereas Ad5- EGFP and Ad5-HSV-TK had no apparent effect on cell proliferation, cell cycle, and cell death as compared to uninfected control. ACC cells did not show marked alterations of gene expression after Ad5-EGFP infection, as demonstrated by microarray analysis in time course infection experiments. In the early phase of infection, genes involved in cell proliferation, stress and innate immune response were transiently upregulated. Moreover, expression of genes encoding steroidogenic enzymes was modulated toward cortisol hypersecretion. With regard to steroidogenesis, ACC cells infected with Ad5 showed decreased basal steroid hormone production in the early phase pi, followed by increased steroid hormone release at 72 h pi. At variance, Ad5-EGFP markedly induced cortisol and estradiol production, but not aldosterone production, at all time points pi. Conclusions: These results, which provide insight into the host response following adenoviral infection of ACC cells, contribute to the understanding of the adrenal involvement during natural adenovirus infection and vector administration for gene therapy.

Ectopic Expression of the Gastric Inhibitory Polypeptide Receptor Gene Is a Sufficient Genetic Event to Induce Benign Adrenocortical Tumor in a Xenotransplantation Model

Aberrant expression of ectopic G protein-coupled receptors (GPCRs) in adrenal cortex tissue has been observed in several cases of ACTH-independent macronodular adrenal hyperplasias and adenomas associated with Cushing's syndrome. Although there is clear clinical evidence for the implication of these ectopic receptors in abnormal regulation of cortisol production, whether this aberrant GPCR expression is the cause or the consequence of the development of an adrenal hyperplasia is still an open question. To answer it, we genetically engineered primary bovine adrenocortical cells to have them express the gastric inhibitory polypeptide receptor. After transplantation of these modified cells under the renal capsule of adrenalectomized immunodeficient mice, tissues formed had their functional and histological characteristics analyzed. We observed the formation of an enlarged and hyperproliferative adenomatous adrenocortical tissue that secreted cortisol in a gastric inhibitory polypeptide-dependent manner and induced a mild Cushing's syndrome with hyperglycemia. Moreover, we show that tumor development was ACTH independent. Thus, a single genetic event, inappropriate expression of a nonmutated GPCR gene, is sufficient to initiate the complete phenotypic alterations that ultimately lead to the formation of a benign adrenocortical tumor.

Aberrant Expression of Human Luteinizing Hormone Receptor by Adrenocortical Cells Is Sufficient to Provoke Both Hyperplasia and Cushing’s Syndrome Features

Aberrant expression of LH/human chorionic gonadotropin (hCG) receptor has been suggested in several cases of bilateral macronodular adrenal hyperplasia with Cushing's syndrome. The cortisol production is then directly controlled by endogenous secretion of LH/hCG. However, the direct involvement of this aberrant LH/hCG receptor expression in the development of the hyperplasia has not been demonstrated. Moreover in most cases, whenever investigated, the aberrant expression of LH/hCG receptor has been associated with the ectopic expression of other G protein-coupled receptors such as gastric inhibitory polypeptide, serotonin, or vasopressin receptors. The aim of this study was to explore the action of LH/hCG receptor on the development of adrenal hyperplasia. The ectopic expression of this single nonmutated gene transduced into bovine adrenocortical cells was sufficient to induce not only the aberrant cortisol secretion but also hyperproliferation and benign transformation. The cells were transplanted beneath the kidney capsule of adrenalectomized immunodeficient mice. Only the cells expressing the LH/hCG receptor gene formed an enlarged tissue with a high proliferation rate. The tissue expressing LH/hCG receptor was responsible for elevated plasma cortisol and decreased plasma ACTH levels in transplanted mice. These animals displayed physiological changes similar to those of patients with Cushing's syndrome, including muscle atrophy, thin skin, spleen atrophy, and hyperglycemia. These results demonstrate that a single genetic event such as the inappropriate expression of the nonmutated LH/hCG receptor gene is sufficient to initiate the phenotypic changes that cause the development of a benign adrenocortical tumor.

A unique case of a benign adrenocortical tumor with triple secretion of cortisol, androgens, and aldosterone. Development of multiple sclerosis after surgical removal of the tumor

We present a 39-year old female with a benign adrenal tumor characterized by autonomous secretion of cortisol, androgens, and aldosterone. The patient presented with a 4-year history of hypertension and severe hirsutism. Baseline investigations revealed elevated testosterone, androstendione, and 17OH progesterone with normal levels of dehydroepi androsterone sulfate. CT of the adrenals revealed a 2.5 x 3.0 cm tumor with characteristics of an adenoma on the left adrenal gland. Pelvic ultrasound was normal. Further investigations revealed suppressed basal ACTH levels, loss of diurnal rhythm of cortisol, and failure to suppress on low dose dexamethasone suppression test, suggesting autonomous cortisol secretion by the tumor. She had an exaggerated response of 17OH progesterone to ACTH, implying reduced 21-hydroxylase activity. An elevated plasma aldosterone concentration to plasma renin activity ratio was suggestive of hyperaldosteronism, which was confirmed by failure of aldosterone to suppress to a formal saline infusion test. Complete clinical and biochemical remission of the disease was observed after left adrenalectomy. Histology confirmed the presence of an adrenocortical adenoma. The patient developed multiple sclerosis 6 months after the operation. The flare-up of an autoimmune disease (multiple sclerosis) postoperatively could be coincidental or possibly related to the high normalization of the high cortisol levels acting as a precipitating factor.

AKT Is Highly Phosphorylated in Pheochromocytomas But Not in Benign Adrenocortical Tumors

Activation of AKT plays a major role in a variety of human neoplasias. In mice, a heterozygous deletion of the Pten gene is associated with increased activation of AKT and with development of pheochromocytomas. The objective of this study was the investigation of the role of AKT in the pathogenesis of pheochromocytomas and adrenocortical tumors. Total AKT and phosphorylated AKT (pAKT) in 15 pheochromocytomas, nine aldosterone-producing adenomas, nine cortisol-producing adenomas, eight adrenocortical carcinomas (ACC), and 15 normal adrenals were investigated by Western blot analysis. Immunohistochemistry for total AKT and pAKT was performed in pheochromocytomas (n = 8), ACC (n = 4), and normal adrenal glands (n = 2). In addition, in pheochromocytomas PTEN protein expression and PTEN loss of heterozygosity were analyzed. Determination of pAKT/total AKT ratio in adrenal tissues was the main outcome. In comparison to normal adrenals, total AKT expression was elevated in both pheochromocytomas (193 +/- 22%) and ACC (176 +/- 36%). The pAKT/AKT ratio was significantly increased in pheochromocytomas (338 +/- 49% vs. 100 +/- 11%) but not in ACC, aldosterone-producing adenomas, and cortisol-producing adenomas. No loss of heterozygosity of PTEN and no decrease in PTEN protein was detected in pheochromocytomas. Immunohistochemistry showed strong and homogeneous AKT and pAKT staining in pheochromocytomas and focal staining in ACC. Our findings provide evidence for increased activation of AKT in pheochromocytomas but not in adrenocortical adenomas.

Role of the Insulin-like Growth Factor System in Adrenocortical Growth Control and Carcinogenesis

Clinically silent adrenocortical adenomas are the most frequent abnormalities in the adrenal gland. In contrast, adrenocortical carcinoma is a rare tumor with an extremely poor prognosis. The factors responsible for the frequent occurrence of benign adrenocortical tumors on one hand and the rare malignant transformation on the other are not known. Several genetic alterations such as loss of imprinting or loss of heterozygosity of the 11p15 gene locus causing a strong IGF-II overexpression have been demonstrated in the majority of adrenocortical carcinomas. In addition to IGF-II overexpression, increased levels of the IGF-I-receptor and IGFBP-2 have been found in advanced human adrenocortical carcinomas, suggesting an important role for the IGF-system in adrenocortical carcinogenesis. IGFs are potent mitogens regulating growth and apoptosis through interaction with the IGF-I-receptor, and overexpression of the human IGF-I-receptor promotes ligand-dependent neoplastic transformation in a variety of different cell systems. It is evident, therefore, that high levels of IGF-II in combination with overexpression of the IGF-I-receptor can provide a significant growth advantage for adrenocortical carcinoma cells and thus contribute to the highly malignant phenotype of this rare type of cancer. Additionally, it has been shown that overexpression of IGFBP-2 can promote malignant transformation of Y1 mouse adrenocortical tumor cells through unknown IGF-independent mechanisms. As one possible mechanism, we have recently found altered expression of catalase in IGFBP-2-overexpressing tumor cells, thus implicating IGFBP-2 in influencing intracellular peroxide levels. However, since transgenic mice with IGF-II or IGFBP-2 overexpression in the adrenal gland do not show an increased frequency of adrenal tumors, IGF-II or IGFBP-2 may act as progression factors but not as initiation factors in adrenocortical tumorigenesis.

Characterization of human NOV in biological fluids: an enzyme immunoassay for the quantification of human NOV in sera from patients with diseases of the adrenal gland and of the nervous system.

Immunochromatography has shown that human NOV (NOVH), a member of the CCN (CTGF/CYR61/NOV) family, forms a physiological complex with fibulin-1 in blood. We developed an enzyme immunoassay specific for NOVH and showed for the first time that the concentration of NOVH differs in each of these biological fluids. The normal concentration of NOVH circulating in the blood is 350-400 ng/ml, but this concentration varies with age. By using sera from patients with adrenal gland diseases we found that in vivo ACTH or glucocorticoids are not responsible for the high concentration of NOVH in this endocrine gland. However, the NOVH concentration was significantly modified in malignant adrenocortical tumors, but not in benign adrenocortical tumors. The concentration of NOVH was significantly decreased in patients suffering from astrocytomas or multiple sclerosis, two diseases of the nervous system. Thus, NOVH is a potentially useful marker for the diagnosis of these diseases.

Weiss system revisited: a clinicopathologic and immunohistochemical study of 49 adrenocortical tumors.

The definitive diagnostic criteria for malignant adrenocortical tumors are distant metastasis and/or local invasion. The Weiss histopathologic system is the most commonly used method for assessing malignancy because of its simplicity and reliability. Unfortunately, its application remains subjective. This current retrospective study evaluated the Weiss system and assessed the value of MIB-1 labeling in the diagnosis of adrenocortical malignancy. Twenty-four malignant tumors with distant metastasis, gross local invasion, or recurrence were selected and matched on their functioning status to 25 benign tumors. Two independent observers delineated the Weiss criteria. An MIB-1 labeling index was determined. Presence of three or more Weiss microscopic criteria was related to malignancy (specificity 96%, sensitivity 100%), thus confirming the value of the Weiss system. Interobserver agreement for the Weiss system (total score) was excellent (r = 0.94). The lack of reliability for some Weiss criteria led us to propose a statistically modified system, based on the most reliable criteria (2.mitotic rate x 2.cytoplasm x abnormal mitoses x necrosis x capsular invasion) with a significant correlation with the Weiss system (r = 0.98). The MIB-1 labeling index was significantly higher in malignant tumors (p <0.0001). MIB1 could also help to differentiate malignant from benign adrenocortical tumors.

The Expression of novH in Adrenocortical Cells Is Down-regulated by TGFβ1 through c-Jun in a Smad-independent Manner

The human NOV secreted glycoprotein (NOVH) is abundant in the fetal and adult adrenal cortex. The amount of NOVH increases in benign adrenocortical tumors and decreases in malignant adrenocortical tumors, suggesting that NOVH plays a role in tumorigenesis in the adrenal cortex. Transforming growth factor beta1 (TGFbeta1), fibroblast growth factor 2 (FGF2), and insulin growth factors (IGFs) play crucial roles in the physiology of the adrenal cortex. We investigated the effects of these factors on the expression of novH in the NCI H295R adrenocortical cell line. The amounts of NOVH protein and novH transcripts were down-regulated by TGFbeta1 and up-regulated by FGF2, whereas IGFs had no effect. Furthermore, the TGFbeta1-dependent inhibition of novH promoter activity was completely abrogated following site-directed mutation of two activating protein (AP-1) sequences (positions -473 and -447), whereas the stimulatory effect of FGF2 was not affected. Co-transfection with dominant negative forms of c-Jun and MEKK1 also abrogated novH-targeted regulation by TGFbeta1, whereas the overproduction of Smad proteins or dominant negative forms of Smad had no effect. Taken together, these results suggest that c-Jun and MEKK1 signaling but not Smad signaling are involved in the TGFbeta1-dependent decrease in NOVH in NCI H295R cells. In conclusion, our data provide evidence that novH is a new target of TGFbeta1; unlike other members of the CCN (cyr61, ctgf, nov) family, however, its expression is repressed rather than induced.

The ectopic expression of the gastric inhibitory polypeptide receptor is frequent in adrenocorticotropin-independent bilateral macronodular adrenal hyperplasia, but rare in unilateral tumors.

Control of cortisol secretion by the abnormal expression of the gastric inhibitory polypeptide receptor (GIP-R) have been observed in some rare cases of ACTH-independent, food-dependent Cushing's syndrome (FD-ACS) due to adrenal adenoma (AA) or bilateral macronodular hyperplasia (AIMAH). This study was performed to determine the prevalence of GIP-R ectopic expression in ACS and its correlation with fasting cortisol levels. GIP-R expression was studied by RT-PCR in 30 unilateral adrenal tumors [16 AA and 14 adrenocortical cancer (AC)] and 8 AIMAH tissues. Fasting and postprandial cortisol levels were assayed, respectively, at 0800 and 1200 h in AA, AC, and AIMAH, and 1 h after a morning standard meal in 6 AIMAH patients. Similar expression of 2 GIP-R isoforms was observed in 1 of 16 AA, 0 of 14 AC, and 4 of 8 AIMAH as well as in the 4 insulinomas used as positive controls. In vitro study of the GIP-R-expressing AA showed stimulation of cortisol secretion and cAMP production by GIP. The fasting 0800-h plasma cortisol level was above 276 nmol/liter in all patients except 1 AA case and 1 AIMAH case, both of whom expressed GIP-R. In the 3 additional AIMAH cases that expressed the GIP-R, fasting plasma cortisol levels were above 276 nmol/liter. This study demonstrates that ectopic expression of GIP-R is rare in AA and is usually associated with the low fasting plasma cortisol levels that characterize FD-ACS. In contrast, GIP-R expression is frequent in AIMAH and might not always be associated with a low fasting plasma cortisol level. This suggests that maintenance of hypercortisolemia in GIP-R- expressing AIMAH does not always depend solely on GIP-R, and that simultaneous abnormal expression of other membrane receptors might be present. The expression of GIP-R could not be observed during malignant transformation of the adrenal cortex. This study highlighted the major role of cAMP alterations secondary to GIP-R ectopic expression in the pathophysiology of AIMAH and in some rare cases of well differentiated benign adrenocortical tumors.

Genetic background of adrenocortical tumor development.

The increasing occurrence of incidentally discovered benign adrenocortical tumors has become a clinical dilemma because of the difficulties in differentiating them from their malignant counterpart. Adrenocortical tumors are associated with familial cancer syndromes such as the Beckwith-Wiedemann syndrome, the Li-Fraumeni syndrome, the Carney complex, multiple endocrine neoplasia type 1, congenital adrenal hyperplasia, and the McCune-Albright syndrome. Genetic events are known to take place on the chromosomal and gene level in sporadic adrenocortical tumors.

A rare case with Icenko-Cushing syndrome caused by multiple bilateral benign and malignant adrenocortical tumors

The article is devoted to the descripition of the rare case with Icenko-Cushing syndrome caused by multiple bilateral benign and malignant adrenocortical tumors.

Role of ACTH receptor in adrenocortical tumor formation.

Adrenocorticotrophin (ACTH) is the major regulatory hormone of steroid synthesis and secretion by adrenocortical cells. The actions of ACTH are mediated by its specific membrane receptor (ACTH-R). The human ACTH-R gene was recently cloned, allowing systematic determination of its sequence, expression and function in adrenal tumorigenesis. The presence of oncogenic mutations of the ACTH-R gene in adrenocortical tumors has been reported. Direct sequencing of the entire coding region of the ACTH-R gene of sporadic adrenocortical adenomas and carcinomas did not reveal constitutive activating mutations, indicating that this mechanism is not frequent in human adrenocortical tumorigenesis. Recent studies demonstrated allelic loss of the ACTH-R gene in a subset of sporadic adrenocortical tumors using a PstI polymorphism located in the promoter region of the ACTH-R gene. Loss of heterozygosity of the ACTH-R was analyzed in 20 informative patients with a variety of benign and malignant adrenocortical tumors. Three of them showed loss of heterozygosity of the ACTH-R gene. In addition, Northern blot experiments demonstrated reduced expression of ACTH-R mRNA in these three tumors with loss of heterozygosity, suggesting the functional significance of this finding at the transcriptional level. Deletion of the ACTH-R gene seems to be involved in a subset of human adrenocortical tumors, contributing to cellular dedifferentiation.

Gastric Stromal Sarcoma, Pulmonary Chondroma, and Extra-adrenal Paraganglioma (Carney Triad): Natural History, Adrenocortical Component, and Possible Familial Occurrence

To investigate the natural history of the triad of gastric stromal sarcoma, pulmonary chondroma, and extra-adrenal paraganglioma, a rare syndrome of unknown cause primarily affecting young women. Mayo Clinic records, the world literature, and the author's files were searched for patients with all or 2 of the 3 tumors. Seventy-nine patients, 67 women and 12 men, were identified, 17 (22%) with the 3 tumors and 62 (78%) with 2 tumors. Forty-two (53%) had gastric and pulmonary tumors, the most common combination. The longest interval between detection of the first and second components was 26 years (mean, 8.4 years; median, 6 years). Follow-up ranged from 1 year to 49 years (mean, 20.6 years; median, 20 years). Sixty-four patients (81%) were alive, 19 (24%) apparently free of disease and 45 (57%) with residual or metastatic tumors. Thirty-two patients (41%) had had 1 or more local recurrences of the gastric sarcoma; the longest interval to first recurrence was 36 years. Twenty-one survivors (27%) had hepatic metastatic gastric sarcoma with follow-up of 1 year to 25 years (mean, 9.3 years; median, 7 years). Fifteen patients (19%) were dead, 10 (13%) of whom died of the disorder. Ten patients (13%) had nonfunctioning adrenocortical tumors. Two patients each had a sibling with 1 component of the triad. The triad is a chronic, persistent, and indolent disease. Benign adrenocortical tumors are a component of the condition. The disorder may be familial.

Detection of Ob-receptor in human adrenal neoplasms and effect of leptin on adrenal cell proliferation.

Leptin, a hormone mainly secreted from adipose tissue, communicates a metabolic signal to the adrenal gland. Ob-Receptor (Ob-R) expression was reported in rat, mice and human adrenal glands. This study intended to investigate possible differences in the Ob-R expression and distribution of Ob-R protein in human adrenal tumors as compared to normal adrenal tissue. Proliferative effects of leptin were analyzed in the human adrenocortical carcinoma cell line (NCI-H295). The full length Ob-R mRNA and the isoforms B219.1 and B219.3 could be demonstrated by RT-PCR in all adrenal tumors (n=8), the tumor cell line (NCI-H295) and normal tissue. In contrast the Ob-R isoform B219.2 was absent in the carcinoma cell line and in most of the adrenal tumors (n=5), whereas it was present in normal adrenals. The Ob-R protein could be demonstrated in benign and malignant adrenocortical tumors. Pheochromocytomas showed only a weak immunostaining with the human Ob-R antibody. Human leptin did not affect the proliferation or variability of adrenal tumor cells as demonstrated by [3H]-thymidine assay and WST-1 test. In conclusion, although functional leptin receptors are expressed in human adrenal tumors, leptin does not regulate tumor cell proliferation.

Molecular genetics of adrenal cortical tumors

The incidental detection of small benign adrenocortical tumors has increased in patients who are investigated with imaging techniques in the upper abdomen. Because these benign lesions are difficult to differentiate from their rare malignant counterparts, the interest to find better tumor markers has increased. In this overview of genetic events in adrenocortical tumors the cancer syndromes Li-Fraumeni, Beckwith-Wiedemann, multiple endocrine neoplasia type 1, congenital adrenal hyperplasia, Carney complex, and McCune-Albright are discussed. Moreover, molecular and cytogenetic analysis on sporadic adrencortical tumors indicate that chromosomes 2, 4, 5, 11, 17, and 18 may harbor genes of importance for the malignant transition of this tumor form. Candidate genes such as IGF2, TP53, and ACT-R are located on these chromosomes and have shown alterations.

MEN1 gene analysis in sporadic adrenocortical neoplasms.

Adrenocortical tumors occur as sporadic tumors, as part of the multiple endocrine neoplasia type 1 (MEN1) syndrome or as part of other hereditary disorders. We recently cloned the MEN1 gene, a tumor-suppressor gene located on chromosome 11q13. Subsequently, we showed that sequential somatic inactivation of both alleles of the MEN1 gene contributes to the development of some sporadic endocrine neoplasms (parathyroid, enteropancreatic neuroendocrine, bronchial carcinoid, and pituitary tumors). We now studied whether somatic inactivation of the MEN1 gene contributes to the pathogenesis of sporadic adrenocortical neoplasms. Seven adrenocortical carcinomas, 2 adrenocortical carcinoma cell lines, and 11 aldosterone-secreting, 8 cortisol-secreting, and 5 nonsecreting benign adrenocortical tumors were studied. Seven tumors (5 of 5 carcinomas, 2 of 21 nonsecreting benign adenomas; P < 0.001) exhibited loss of heterozygosity on 11q13. All 33 tumors and cell lines were screened for mutation throughout the MEN1 open-reading frame and adjacent splice junctions. None exhibited a mutation within the MEN1-coding region. We conclude that somatic MEN1 mutation within the MEN1-coding region does not occur commonly in sporadic adrenocortical tumors, although the majority of adrenocortical carcinomas exhibit 11q13 loss of heterozygosity.

Deletion of the adrenocorticotropin receptor gene in human adrenocortical tumors: implications for tumorigenesis.

Constitutive activating mutations of G protein-coupled receptors, such as that of TSH, have been implicated in the tumorigenesis of human endocrine neoplasms, such as thyroid adenomas. In a previous study we reported that constitutive activating point mutations of the ACTH receptor (ACTH-R) gene, a member of the G protein-coupled receptor superfamily, were not present in hormone-secreting and nonsecretory adrenocortical neoplasms. In this study, we investigated whether allelic loss of the ACTH-R gene is present in sporadic adrenal tumors. We identified a PstI polymorphism in the promoter region 3 kilobases upstream of the coding region of the ACTH-R gene. The rate of heterozygosity for this polymorphism in 99 unrelated Caucasian individuals was 53.5%. Using this polymorphism, we analyzed loss of heterozygosity (LOH) of the ACTH-R gene in 20 informative cases with benign and malignant adrenocortical tumors. Of 16 patients with benign lesions, LOH was present in 1 oncocytic nonfunctional adenoma, but not in 15 hyperfunctioning adenomas. Of 4 informative patients with adrenocortical carcinomas, LOH was present in 2 cases. Both patients had advanced tumor stages and showed a more rapid course than carcinoma patients without LOH. Analysis of the flanking region of the ACTH-R using the polymorphic microsatelite marker D18S37 and D18S40 showed that this deletion was confined to the ACTH-R gene. Northern blot experiments demonstrated reduced expression of ACTH-R messenger ribonucleic acid in the tumors with LOH of the ACTH-R gene, suggesting functional significance of this finding at the transcriptional level. We conclude that LOH of the ACTH-R gene is possibly involved in adrenal tumorigenesis, contributing to cellular dedifferentiation in adenomas and carcinomas.

Are activating mutations of the adrenocorticotropin receptor involved in adrenal cortical neoplasia?

The objective of this study was to investigate the presence of activating mutations of the ACTH receptor gene in benign and malignant adrenocortical tumours. Genomic DNA was extracted from a variety of adrenocortical neoplasms from 16 patients and the entire ACTH receptor gene was then amplified by the polymerase chain reaction and sequenced. No mutations were detected within the coding region of the ACTH receptor gene in the 16 adrenocortical tumours studied. It is likely that mutations of the coding region of the ACTH receptor gene do not play a major role in adrenocortical tumourigenesis.