[Frontiers in Bioscience 14, 3304-3309, January 1, 2009]

Somatostatin receptor expression in thymic tumors

Diego Ferone1, Liliana Montella2, Annarosaria De Chiara3, Leo J Hofland4, Steven WJ Lamberts4, Giovannella Palmieri5,6

1Department of Endocrinology and Medical Sciences and Center of Excellence for Biomedical Research, University of Genova, viale Benedetto XV, 6, Genova; 2Medical Oncology, n.3 Naples Local Health Unit, "S.Giovanni di Dio" Hospital, Frattamaggiore, Naples, Italy; 3Unit of Pathology, National Cancer Institute "Fondazione G. Pascale", via M. Semmola, Naples; 4Department of Internal Medicine, Section Endocrinology, Erasmus Medical Center, Rotterdam, The Netherlands; 5Department of Molecular and Clinical Endocrinology & Oncology, University "Federico II", Naples, and 6 Casa di Cura "Villa Maria", Mirabella Eclano, Avellino, Italy

TABLE OF CONTENTS

1. Abstract
2. Introduction
3. Materials and Methods
3.1. Patients
3.2. Scintigraphic studies
3.3. Tissue samples
3.4. Immunohistochemical localization of sst2 and sst3 receptors
4. Results
4.1. Somatostatin receptor scintigraphy
4.2. Immunohistochemical detection of sst2 and sst3 receptors
4.3. Comparative analysis of in vitro and in vivo results
5. Discussion
6. Acknowledgement
7. References

1. ABSTRACT

Detection of thymic tumors by (111In-DTPA0)octreotide scintigraphy and the antitumor effect exerted by somatostatin (SS) analogs suggest significant expression of SS receptors (SSRs) in these tumors. We measured SSR subtype (sst)2A and sst3 expression by immunohistochemistry (IHC) in 14 thymic tumors previously studied by SSR scintigraphy (SRS). Scintigraphy showed significant (111In-DTPA0)octreotide uptake in 13/14 tumors (tumor-to-background ratios: 1.4- to 6-fold). By IHC, 4 tumors were positive for sst2A and sst3; two for sst2A and five tumors for sst3. Three tumors were completely negative. Overall, 11/14 (approximately 78% of cases) expressed at least one SSR subtype. Staining was highly heterogeneous: sst2A was confined to malignant epithelial cells or within stromal structures, and sst3 was predominantly associated with thymocytes. SRS provides immediate visualization of primary and metastatic lesions, while IHC reveals SSR subtype expression. This joined approach could help to select SS analogs beneficial for therapy.