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L Barzon, R Bonaguro, G Palu and M Boscaro

Gene therapy for endocrine diseases represents an exciting new type of molecular intervention that may be a curative one. Endocrine disorders that might be treated by gene therapy include monogenic diseases, such as GH deficiency and hypothalamic diabetes insipidus, and multifactorial diseases, such as diabetes mellitus, obesity and cancer. Premises seem promising for endocrine tumours, but many combined approaches of cell and gene therapy are foreseeable also for other endocrine disorders. This review outlines the principles of gene therapy, describes the endocrine disorders that might take advantage of gene transfer approaches, as well as the gene therapy interventions that have already been attempted, their major limitations and the problems that remain to be solved.

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L Barzon, F Fallo, N Sonino and M Boscaro

OBJECTIVE: The natural course of adrenal incidentalomas, especially those with subclinical autonomous glucocorticoid production, i.e. subclinical Cushing's syndrome, and the risk that such conditions will evolve towards overt Cushing's syndrome are unknown. DESIGN: Longitudinal follow-up evaluation of a series of 284 consecutive patients with adrenal incidentaloma. METHODS AND RESULTS: Out of 284 consecutive patients with adrenal incidentaloma studied at our Institution in the last 15 years, 98 patients (23 with subclinical hypercortisolism) underwent surgery. Of 130 non-operated patients with a follow-up of at least 1 year, eight had subclinical hypercortisolism at diagnosis. We describe in detail four patients who developed overt Cushing's syndrome after 1-3 years of follow-up. Only one of these patients had subclinical hypercortisolism at first diagnosis. Estimated cumulative risk for a non-secreting adrenal incidentaloma to develop subclinical hyperfunction was 3.8% after 1 year and 6.6% after 5 years. For patients with masses with subclinical autonomous glucocorticoid overproduction, estimated cumulative risk to develop overt Cushing's syndrome was 12.5% after 1 year. CONCLUSIONS: In patients with adrenal incidentalomas the risk of progression towards overt Cushing's syndrome is not low, at variance with previous reports. A careful biochemical and hormonal follow-up is advisable in all patients who do not need surgery at first presentation.

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L Barzon, N Sonino, F Fallo, G Palu and M Boscaro

Clinically silent adrenal masses discovered by imaging studies performed for unrelated reasons, i.e. adrenal incidentalomas, have become a rather common finding in clinical practice. However, only limited studies of incidence, prevalence, and natural history of adrenal incidentalomas are available. A comprehensive review of the literature shows the prevalence of adrenal incidentalomas to be 2.3% at autopsy and 0.5-2% at abdominal computed tomography scan. Most lesions are adrenocortical adenomas at histology, whereas the prevalence of adrenocortical carcinomas is relatively low. The risk of malignancy over time for masses defined as benign at diagnosis is estimated at about 1/1000, even though 5-25% of masses increase in size during follow-up. Hyperfunction develops in about 1.7% of cases and the risk is higher in patients with lesions larger than 3 cm. Cortisol hypersecretion is the most likely disorder that may ensue, and it remains subclinical in about two-thirds of cases. The lack of controlled studies precludes making specific management recommendations. Large perspective controlled studies to define the epidemiology, natural history, and possible associated morbidity of adrenal incidentalomas and their impact on the quality of life of patients are needed.

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L Barzon, M Chilosi, F Fallo, G Martignoni, L Montagna, G Palu and M Boscaro

OBJECTIVE: To evaluate the roles of the CDKN1C (P57KIP2) gene, which encodes for the cyclin-dependent kinase inhibitor CDNC, and the TP53 tumor suppressor gene in adrenal tumorigenesis, as a means of investigating the molecular basis of sporadic adrenal tumors, which is unknown. DESIGN: Screening for the presence CDKN1C and TP53 mutations and analyzing the expression pattern of CDNC, P53 and its downstream effector CDN1 (P21WAF1/CIP1) in a series of 79 sporadic adrenal tumors. METHODS: Single-strand conformation polymorphism and sequencing were used for mutation analysis of CDKN1C and TP53 in blood and adrenal tissue samples. In a subgroup of 48 tissues, CDKN1C expression was evaluated by RT-PCR and immunohistochemistry. Immunohistochemical analysis of P53 and CDN1 was performed. RESULTS: No somatic mutations of CDKN1C were found in the tumors analyzed, in spite of low/absent CDNC expression in adrenocortical adenomas and carcinomas. Mutations in the TP53 gene were present in 70% of adrenocortical carcinomas, associated with abnormal P53 and CDN1 expression, but not in benign neoplasms. In the normal adrenal cortex, CDNC expression was strictly nuclear and confined to the cortical zone (i.e. zona glomerulosa and reticularis), with no staining in the medulla. CONCLUSIONS: Mutations in the TP53 gene are frequent in adrenocortical carcinomas and might be used as a marker of malignancy. In the normal adrenal cortex, the zone-specific pattern of expression of CDNC suggests a role in adrenal differentiation.

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L Barzon, G Masi, K Fincati, M Pacenti, V Pezzi, G Altavilla, F Fallo and G Palù

Objective: Adrenocortical tumors may originate from the zona glomerulosa, zona fasciculata, or zona reticularis and be associated with syndromes due to overproduction of mineralocorticoids, glucocorticoids, or androgens respectively. We report an unusual case of recurrent adrenocortical carcinoma (ACC), which seems to contradict the paradigm of functional adrenal zonation.

Case report: A male patient presented with severe primary aldosteronism due to an ACC, which relapsed after adrenalectomy and adjuvant mitotane therapy. After removal of the tumor recurrence and eight cycles of chemotherapy with etoposide, doxorubicin and cisplatin, the patient presented again with ACC masses, but in association with overt Cushing’s syndrome and normal aldosterone levels.

Methods and results: Extensive pathologic examination showed that this shift in steroid hormone production was paralleled by an attenuation of tumor cell atypia and polymorphism, whereas gene expression profile analysis demonstrated a change in expression of adrenal steroidogenic enzymes. Moreover, cancer progression was associated with overexpression of the inhibin-α subunit, which could have contributed to the phenotypic changes.

Conclusions: This case of recurrent ACC demonstrates that adrenocortical cells can reverse their differentiation program during neoplastic progression and change their specific hormone synthesis, as a consequence of modifications in the expression profile of steroidogenic enzymes and cofactors. We hypothesize that this shift in steroid hormone secretion is a consequence of chromosome amplification induced by chemotherapy. These findings, besides opening new perspectives to study adrenocortical cell plasticity and potential, demonstrate how conventional clinical and pathologic evaluation can be combined with genomic analysis in order to dissect thoroughly the biology of cancer.

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L Barzon, P Zucchetta, M Boscaro, MC Marzola, F Bui and F Fallo

OBJECTIVE: Adrenocortical scintigraphy has demonstrated clinical utility in the morpho-functional characterization of adrenal tumors. The aim of this study was to identify possible relationships between the scintigraphic pattern and endocrine and/or morphological data in a series of adrenocortical carcinomas. DESIGN AND METHODS: Twenty-one patients with adrenocortical carcinoma (11 nonfunctioning and 10 hormone-secreting) were investigated with 75Se-methyl-nor-cholesterol scintigraphy. Clinical, hormonal, radiological, and pathological data were analyzed. RESULTS: The adrenal mass showed no radiocholesterol uptake in 18 cases (11 nonfunctioning and 7 functioning lesions). Contralateral normal adrenal gland was visualized in all patients with nonfunctioning tumors, whereas classic bilateral nonvisualization was observed in the 7 cases with hyperfunctioning masses. Three patients with cortisol-producing carcinomas showed radiotracer uptake by the mass, without visualization of the contralateral gland. At histology, the tumors were shown to be undifferentiated adrenocortical carcinomas; they had an aggressive clinical behavior. CONCLUSIONS: Radiocholesterol scintigraphy has an important role in diagnosing adrenocortical carcinomas, which typically are not visualized. However, 30% of hypersecreting adrenocortical carcinomas show an atypical increased tracer uptake, not predictive of the biochemical and histological features of the tumor.

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F Fallo, V Pezzi, L Barzon, P Mulatero, F Veglio, N Sonino and JM Mathis

BACKGROUND: The presence and pathophysiological role of CYP11B1 (11beta-hydroxylase) gene in the zona glomerulosa of human adrenal cortex is still controversial. METHODS: In order to specifically quantify CYP11B1, CYP11B2 (aldosterone synthase) and CYP17(17alpha-hydroxylase) mRNA levels, we developed a real-time RT-PCR assay and examined the expression in a series of adrenal tIssues, including six normal adrenals from patients adrenalectomized for renal cancer and twelve aldosterone-producing adenomas (APA) from patients with primary aldosteronism. RESULTS: CYP11B1 mRNA levels were clearly detected in normal adrenals, which comprised both zona glomerulosa and fasciculata/reticularis cells, but were also measured at a lower range (P<0.05) in APA. The levels of CYP11B2 mRNA were lower (P<0.005) in normal adrenals than in APA. CYP17 mRNAlevels were similar in normal adrenals and in APA. In patients with APA, CYP11B2 and CYP11B1 mRNA levels were not correlated either with basal aldosterone or with the change from basal aldosterone in response to posture or to dexamethasone. No correlation between CYP11B1 mRNA or CYP11B2 mRNA and the percentage of zona fasciculata-like cells was observed in APA. CONCLUSIONS: Real-time RT-PCR can be reliably used to quantify CYP11B1 and CYP11B2 mRNA levels in adrenal tIssues. Expression of CYP11B1 in hyperfunctioning zona glomerulosa suggests an additional formation of corticosterone via 11beta-hydroxylase, providing further substrate for aldosterone biosynthesis. CYP11B1 and CYP11B2 mRNA levels in APA are not related to the in vivo secretory activity of glomerulosa cells, where post-transcriptional factors might ultimately regulate aldosterone production.

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L Barzon, R Bonaguro, I Castagliuolo, M Chilosi, E Franchin, C Del Vecchio, I Giaretta, M Boscaro and G Palu

OBJECTIVE AND DESIGN: Based on our clinical experience with combined gene therapy of glioblastoma, we developed a retroviral vector expressing two therapeutic genes (i.e. thymidine kinase of herpes simplex virus, HSV-TK, and interleukin-2, IL-2) and evaluated its efficiency in vitro and in vivo. METHODS: Expression of therapeutic genes in transduced thyroid carcinoma cells was analyzed by real-time RT-PCR. Ganciclovir sensitivity of infected cells was assessed in vitro in thyroid carcinoma cell lines and in vivo in nude mice bearing xenografted thyroid cancers. The combined effect of IL-2/HSV-TK was compared with the effect of IL-2 alone. RESULTS: Expression of therapeutic genes was higher in differentiated than in anaplastic thyroid carcinoma cells. Ganciclovir treatment led to dose- and time-dependent killing of transduced cells in vitro. A bystander effect was demonstrated by using mixtures of infected and non-infected cells. In vivo studies showed a significant reduction of growth and the presence of an inflammatory infiltrate in transduced thyroid tumors expressing IL-2 alone, as compared with non-infected tumors. By using the retroviral vector expressing IL-2/HSV-TK, treatment with ganciclovir led to complete eradication of anaplastic tumors and a >80% reduction of the size of differentiated thyroid carcinomas. Histological analysis of tumor specimens showed extensive necrosis and inflammatory cell infiltrates. The combination of IL-2/HSV-TK plus ganciclovir was significantly more efficient than IL-2 alone in eradicating tumor masses. The bystander effect was also obtained in vivo. CONCLUSIONS: These findings demonstrate the feasibility and efficiency of a combined immunomodulating and suicide gene therapy approach for thyroid carcinomas.