While somatostatin receptors (sst), through somatostatin-radiolabeled analogs, are used, mainly in second line, in the diagnosis and treatment of pheochromocytomas (PCC) and paragangliomas (PGL), the clinical significance of dopamine receptor subtype 2 (D2) in PCC/PGL is unknown. Indeed, radiolabeled dopamine (DA) analogs such as fluorine 18 (18F)-DA, used for positron emission tomography in PCC localization, are mainly correlated to the presence of noradrenaline transporter (NAT) and vesicular monoamine transporters (VMAT) but not to D2. The aim of this study was to quantitate D2 and sst expression in 52 PCC/PGL and to compare it with that of 35 gastroenteropancreatic neuroendocrine tumors (GEP-NETs). Quantitative RT-PCR of sst 1–3 and sst 5, D2, NAT, VMAT1/2 was performed in all tumors, while immunohistochemistry analysis of sst2 and D2 was performed in seven tumors. D2 mRNA was expressed in all PCC/PGL. Mean expression was significantly higher in PCC/PGL than in GEP-NETs (4.8 vs 0.5 copy/copy β-glucuronidase (Gus)). sst2 and sst1 were expressed in most PCC/PGL, with sst2-dominant expression (mean mRNA: 1.6 vs 0.4 copy/copy β-Gus). sst2 expression level was similar to that of GEP-NETs, whereas sst5 expression level was significantly lower (0.12 vs 0.78 copy/copy β-Gus). Our study evidenced strong D2 mRNA expression in PCC and for the first time in PGL. PCC/PGL express sst 2 mRNA at levels similar to those of GEP-NETs. New drugs can target ssts and D2 more efficiently than current somatostatin analogs. Moreover, transporters like NAT and VMAT1/2, could be co-targeted with sst, as a basis of new radionuclide compounds in the imaging and treatment of these tumors.
Alexandru Saveanu, Mihaela Muresan, Catherine De Micco, David Taieb, Anne-Laure Germanetti, Frederic Sebag, Jean-François Henry, Laurent Brunaud, Alain Enjalbert, Georges Weryha and Anne Barlier
Birke Bausch, Ulrich Wellner, Dirk Bausch, Francesca Schiavi, Marta Barontini, Gabriela Sanso, Martin K Walz, Mariola Peczkowska, Georges Weryha, Patrizia Dall'Igna, Giovanni Cecchetto, Gianni Bisogno, Lars C Moeller, Detlef Bockenhauer, Attila Patocs, Karoly Rácz, Dmitry Zabolotnyi, Svetlana Yaremchuk, Iveta Dzivite-Krisane, Frederic Castinetti, David Taieb, Angelica Malinoc, Ernst von Dobschuetz, Jochen Roessler, Kurt W Schmid, Giuseppe Opocher, Charis Eng and Hartmut P H Neumann
A third of patients with paraganglial tumors, pheochromocytoma, and paraganglioma, carry germline mutations in one of the susceptibility genes, RET, VHL, NF1, SDHAF2, SDHA, SDHB, SDHC, SDHD, TMEM127, and MAX. Despite increasing importance, data for long-term prognosis are scarce in pediatric presentations. The European-American-Pheochromocytoma–Paraganglioma-Registry, with a total of 2001 patients with confirmed paraganglial tumors, was the platform for this study. Molecular genetic and phenotypic classification and assessment of gene-specific long-term outcome with second and/or malignant paraganglial tumors and life expectancy were performed in patients diagnosed at <18 years. Of 177 eligible registrants, 80% had mutations, 49% VHL, 15% SDHB, 10% SDHD, 4% NF1, and one patient each in RET, SDHA, and SDHC. A second primary paraganglial tumor developed in 38% with increasing frequency over time, reaching 50% at 30 years after initial diagnosis. Their prevalence was associated with hereditary disease (P=0.001), particularly in VHL and SDHD mutation carriers (VHL vs others, P=0.001 and SDHD vs others, P=0.042). A total of 16 (9%) patients with hereditary disease had malignant tumors, ten at initial diagnosis and another six during follow-up. The highest prevalence was associated with SDHB (SDHB vs others, P<0.001). Eight patients died (5%), all of whom had germline mutations. Mean life expectancy was 62 years with hereditary disease. Hereditary disease and the underlying germline mutation define the long-term prognosis of pediatric patients in terms of prevalence and time of second primaries, malignant transformation, and survival. Based on these data, gene-adjusted, specific surveillance guidelines can help effective preventive medicine.