Pattern of adrenal morphology and function in patients with acromegaly

Does IGF-1 play a role in the etiopathogenesis of non-functioning adrenocortical adenoma?

PURPOSE

The aim of this study was to investigate the possible association of insulin-like growth factor-1 (IGF-1) with the pathogenesis of non-functioning adrenocortical adenomas (NFAs).

METHODS

This study included 50 female patients (mean age 54 years) with NFAs, 55 patients (mean age 48 years; 20 male, 35 female) with acromegaly and 38 female control subjects (mean age 58 years). Body mass index (BMI) and waist circumference (WC) of the subjects were recorded and blood samples for IGF-1 were taken. Insulin resistance was calculated using the homeostatic model assessment (HOMA) score. Since most of the acromegaly patients had been using medicine that could have effected insulin resistance, HOMA scores were calculated only in patients with NFAs and the controls. Computerized tomography or magnetic resonance imaging was taken of the acromegalics and controls to detect adrenal mass frequency.

RESULTS

The mean age was similar among the groups. As expected, the serum IGF-1 levels were significantly higher in patients with acromegaly than in patients with NFAs and the controls (p < 0.001). Although BMI, WC, and serum IGF-1 levels were significantly higher (p < 0.001) in patients with NFAs, the HOMA scores were similar between patients with NFAs and control groups. Although none of the control subjects had adrenal masses, NFAs were detected in 14 (25%) out of 55 acromegalic patients.

CONCLUSIONS

Higher serum IGF-1 levels in patients with NFAs compared to the control group and an increased prevalence of NFAs in acromegaly patients compared to control subjects and the general population suggest an association of IGF-1 with the etiopathogenesis of NFA.

The role of insulin-like growth factor system in the adrenocortical tumors

INTRODUCTION

The different presentation of adrenocortical tumors in benign adenoma (ACA) or adrenocortical carcinoma (ACC) is related to the variability at the molecular level. The insulin-like growth factor (IGF) system is one of the most frequently altered pathways in ACC. In this review we will critically analyze the evidence regarding the pathogenic role of the IGF system in adrenal tumorigenesis, focusing on ACC. We will also examine the preclinical and clinical studies which investigated the targeting of the IGF system as a therapeutic approach in ACC.

EVIDENCE ACQUISITION

The IGF system plays a crucial role in the embryogenesis of adrenal glands. No significant alterations of the IGF system were observed in ACA. In ACC, the IGF2 overexpression is one of the most frequent molecular change presented in more than 85% of cases. However, IGF2 seems to be only a tumor progression factor which requires additional hits to trigger adrenal tumorigenesis. Also, the IGF1 receptor (IGF1R) appears to be higher expressed in ACC. Many IGF1R target-drugs have been developed to inhibit the activation of the IGF system.

EVIDENCE SYNTHESIS

Preclinical studies using antibody or tyrosine kinase which target the IGF1R, or the dual-targeting of IGF1R and insulin receptor (IR) reduced ACC cells proliferation both in vitro and in vivo in mouse xenograft model. However, these promising results were not confirmed in clinical trials.

CONCLUSIONS

Nowadays, predictive markers for the response of target-IGF therapy are missing and further studies which investigate new molecular markers and evaluate the entire IGF receptors, including the IR, are urgently needed.

Poorly-controlled acromegaly accompanied by subclinical adrenal Cushing's syndrome after surgery for multiple endocrine tumors

A 48-year-old woman diagnosed with acromegaly 21 years earlier presented at our hospital with a left adrenal tumor. Her medical history included breast cancer, thyroid cancer and an incompletely resected growth hormone (GH)-producing pituitary adenoma. Endocrinological and radiological examinations revealed subclinical adrenal Cushing's syndrome. She subsequently underwent left adrenalectomy, followed by glucocorticoid replacement therapy. Her GH and insulin-like growth factor-1 levels were insufficiently controlled, and pegvisomant was administered in addition to octreotide acetate. Following adrenalectomy, a giant hepatic hemangioma and papillary thyroid carcinoma in the residual right lobe developed, indicating the high risk of tumor development in patients with acromegaly.

Case Report: A case report of acromegaly associated with primary aldosteronism

We describe a patient with a rare combination of acromegaly and primary aldosteronism. A 37 year-old female patient was diagnosed with acromegaly on the basis of typical clinical, hormonal and image characteristics. She presented also with one of the most common co-morbidities – arterial hypertension. The patient has been regularly followed-up and after three surgical interventions, irradiation and adjuvant treatment with a dopamine agonist, acromegaly was finally controlled in 2008 (20 years after diagnosis). Arterial hypertension however, remained a therapeutic problem even after prescription of four antihypertensive drugs. She had normal biochemical parameters, except for low potassium levels 3.2 (3.5-5.6) mmol/l. This raised the suspicion of primary hyperaldosteronism, confirmed by a high aldosterone to plasma rennin activity ratio, high aldosterone level after a Captopril challenge test and visualization of a 35 mm left adrenal nodule on a CT scan. After an operation, the patient recovered from hypokalemia and antihypertensive therapy was reduced to a small dose of a Ca blocker.

Co-morbid arterial hypertension is common in acromegaly, though it is rare for this to be caused by Conn’s adenoma. The association of Conn’s adenoma with acromegaly has been interpreted in two lines: as a component of multiple endocrine neoplasia type (MEN1) syndrome or as a direct mitogenic effect of hyperactivated GH-IGF1 axis.