Lucie Evenepoel, Raphaël Helaers, Laurent Vroonen, Selda Aydin, Marc Hamoir, Dominique Maiter, Miikka Vikkula and Alexandre Persu
Adrian F Daly, Philippe A Lysy, Céline Desfilles, Liliya Rostomyan, Amira Mohamed, Jean-Hubert Caberg, Veronique Raverot, Emilie Castermans, Etienne Marbaix, Dominique Maiter, Chloe Brunelle, Giampaolo Trivellin, Constantine A Stratakis, Vincent Bours, Christian Raftopoulos, Veronique Beauloye, Anne Barlier and Albert Beckers
X-linked acrogigantism (X-LAG) syndrome is a newly described form of inheritable pituitary gigantism that begins in early childhood and is usually associated with markedly elevated GH and prolactin secretion by mixed pituitary adenomas/hyperplasia. Microduplications on chromosome Xq26.3 including the GPR101 gene cause X-LAG syndrome. In individual cases random GHRH levels have been elevated. We performed a series of hormonal profiles in a young female sporadic X-LAG syndrome patient and subsequently undertook in vitro studies of primary pituitary tumor culture following neurosurgical resection. The patient demonstrated consistently elevated circulating GHRH levels throughout preoperative testing, which was accompanied by marked GH and prolactin hypersecretion; GH demonstrated a paradoxical increase following TRH administration. In vitro, the pituitary cells showed baseline GH and prolactin release that was further stimulated by GHRH administration. Co-incubation with GHRH and the GHRH receptor antagonist, acetyl-(d-Arg2)-GHRH (1-29) amide, blocked the GHRH-induced GH stimulation; the GHRH receptor antagonist alone significantly reduced GH release. Pasireotide, but not octreotide, inhibited GH secretion. A ghrelin receptor agonist and an inverse agonist led to modest, statistically significant increases and decreases in GH secretion, respectively. GHRH hypersecretion can accompany the pituitary abnormalities seen in X-LAG syndrome. These data suggest that the pathology of X-LAG syndrome may include hypothalamic dysregulation of GHRH secretion, which is in keeping with localization of GPR101 in the hypothalamus. Therapeutic blockade of GHRH secretion could represent a way to target the marked hormonal hypersecretion and overgrowth that characterizes X-LAG syndrome.
Iulia Potorac, Patrick Petrossians, Adrian F Daly, Orsalia Alexopoulou, Sophie Borot, Mona Sahnoun-Fathallah, Frederic Castinetti, France Devuyst, Marie-Lise Jaffrain-Rea, Claire Briet, Florina Luca, Marion Lapoirie, Flavius Zoicas, Isabelle Simoneau, Alpha M Diallo, Ammar Muhammad, Fahrettin Kelestimur, Elena Nazzari, Rogelio Garcia Centeno, Susan M Webb, Marie-Laure Nunes, Vaclav Hana, Véronique Pascal-Vigneron, Irena Ilovayskaya, Farida Nasybullina, Samia Achir, Diego Ferone, Sebastian J C M M Neggers, Brigitte Delemer, Jean-Michel Petit, Christof Schöfl, Gerald Raverot, Bernard Goichot, Patrice Rodien, Bernard Corvilain, Thierry Brue, Franck Schillo, Luaba Tshibanda, Dominique Maiter, Jean-François Bonneville and Albert Beckers
GH-secreting pituitary adenomas can be hypo-, iso- or hyper-intense on T2-weighted MRI sequences. We conducted the current multicenter study in a large population of patients with acromegaly to analyze the relationship between T2-weighted signal intensity on diagnostic MRI and hormonal and tumoral responses to somatostatin analogs (SSA) as primary monotherapy. Acromegaly patients receiving primary SSA for at least 3 months were included in the study. Hormonal, clinical and general MRI assessments were performed and assessed centrally. We included 120 patients with acromegaly. At diagnosis, 84, 17 and 19 tumors were T2-hypo-, iso- and hyper-intense, respectively. SSA treatment duration, cumulative and mean monthly doses were similar in the three groups. Patients with T2-hypo-intense adenomas had median SSA-induced decreases in GH and IGF-1 of 88% and 59% respectively, which were significantly greater than the decreases observed in the T2-iso- and hyper-intense groups (P < 0.001). Tumor shrinkage on SSA was also significantly greater in the T2-hypo-intense group (38%) compared with the T2-iso- and hyper-intense groups (8% and 3%, respectively; P < 0.0001). The response to SSA correlated with the calculated T2 intensity: the lower the T2-weighted intensity, the greater the decrease in random GH (P < 0.0001, r = 0.22), IGF-1 (P < 0.0001, r = 0.14) and adenoma volume (P < 0.0001, r = 0.33). The T2-weighted signal intensity of GH-secreting adenomas at diagnosis correlates with hormone reduction and tumor shrinkage in response to primary SSA treatment in acromegaly. This study supports its use as a generally available predictive tool at diagnosis that could help to guide subsequent treatment choices in acromegaly.