Abstract
Somatostatin (SRIH), a cyclic tetradecapeptide hormone originally isolated from mammalian hypothalamus, is a potent suppressor of pituitary growth hormone (GH) secretion. SRIH acts through a family of G-protein-coupled membrane receptors containing seven transmembrane domains. Five genes encoding distinct SRIH receptor (SSTR) subtypes have so far been cloned in human and other species and termed SSTR1-5. In human somatotrophe pituitary adenomas GH secretion is controlled by both SSTR2 and SSTR5. However, in clinical practice only somatostatin analogs selective for SSTR2 (octreotide and lanreotide) are available. This may explain why clinical and in vitro responses to these analogs in acromegaly are only partial. In this study, we investigated the inhibitory effect of two new SRIH analogs with high selectivity for SSTR2 (NC-4-28B) and SSTR5 (BIM-23268) and compared it to that of native somatostatin (SRIH-14) on a large number of GH-secreting adenomas obtained by transphenoidal neurosurgery. Tissues from 16 adenomas were enzymatically dispersed and plated in 24-well dishes at 50,000 cells/well. After 3 days, groups of three wells were incubated for 4 h with medium alone, SRIH-14 or analogs NC-4-28B or BIM-23268, at the concentrations of 0.01, 0.1 and 1 μM. Our results show that 9 out of 16 adenomas were responsive (GH suppression: 20-40% vs. control, p <0.05) to SRIH. In this group only 4 adenomas showed similar responses to both selective analogs, with 2 nonresponders (expression of other SRIH receptor subtypes) and 2 responders (concomitant expression of SSTR2 and SSTR5) to both analogs. GH release was selectively inhibited by NC-4-28B in 3 adenomas and by BIM-23268 in the remaining 2 adenomas, suggesting predominant expression of SSTR2 and SSTR5, respectively. SRIH failed to inhibit GH release in 7 adenomas (43%). Interestingly, in that group a better inhibitory effect was obtained with BIM-23268 (5 out of 7 adenomas) than with NC-4-28B, suggesting expression of a few SSTR5 receptors only, or of both SSTR2 and SSTR5, respectively. We conclude that the availability of somatostatin analogs selective for SSTR5 will enhance the treatment potency and spectrum in acromegaly.
| Original language | English |
|---|---|
| Pages (from-to) | 344-351 |
| Number of pages | 8 |
| Journal | Neuroendocrinology |
| Volume | 73 |
| Issue number | 5 |
| DOIs | |
| Publication status | Published - 2001 |
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Keywords
- Adenomas
- Clinical neuroendocrinology
- Growth hormone
- Somatostatin
- Somatostatin analogs
- Somatostatin receptors
ASJC Scopus subject areas
- Endocrinology
- Neuroscience(all)
Cite this
Differential inhibition of growth hormone secretion by analogs selective for somatostatin receptor subtypes 2 and 5 in human growth-hormone-secreting adenoma cells in vitro. / Tulipano, Giovanni; Bonfanti, Carlo; Milani, Gabriella; Billeci, Bruno; Bollati, Angelo; Cozzi, Renato; Maira, Giulio; Murphy, William A.; Poiesi, Claudio; Turazzi, Sergio; Giustina, Andrea.
In: Neuroendocrinology, Vol. 73, No. 5, 2001, p. 344-351.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Differential inhibition of growth hormone secretion by analogs selective for somatostatin receptor subtypes 2 and 5 in human growth-hormone-secreting adenoma cells in vitro
AU - Tulipano, Giovanni
AU - Bonfanti, Carlo
AU - Milani, Gabriella
AU - Billeci, Bruno
AU - Bollati, Angelo
AU - Cozzi, Renato
AU - Maira, Giulio
AU - Murphy, William A.
AU - Poiesi, Claudio
AU - Turazzi, Sergio
AU - Giustina, Andrea
PY - 2001
Y1 - 2001
N2 - Somatostatin (SRIH), a cyclic tetradecapeptide hormone originally isolated from mammalian hypothalamus, is a potent suppressor of pituitary growth hormone (GH) secretion. SRIH acts through a family of G-protein-coupled membrane receptors containing seven transmembrane domains. Five genes encoding distinct SRIH receptor (SSTR) subtypes have so far been cloned in human and other species and termed SSTR1-5. In human somatotrophe pituitary adenomas GH secretion is controlled by both SSTR2 and SSTR5. However, in clinical practice only somatostatin analogs selective for SSTR2 (octreotide and lanreotide) are available. This may explain why clinical and in vitro responses to these analogs in acromegaly are only partial. In this study, we investigated the inhibitory effect of two new SRIH analogs with high selectivity for SSTR2 (NC-4-28B) and SSTR5 (BIM-23268) and compared it to that of native somatostatin (SRIH-14) on a large number of GH-secreting adenomas obtained by transphenoidal neurosurgery. Tissues from 16 adenomas were enzymatically dispersed and plated in 24-well dishes at 50,000 cells/well. After 3 days, groups of three wells were incubated for 4 h with medium alone, SRIH-14 or analogs NC-4-28B or BIM-23268, at the concentrations of 0.01, 0.1 and 1 μM. Our results show that 9 out of 16 adenomas were responsive (GH suppression: 20-40% vs. control, p <0.05) to SRIH. In this group only 4 adenomas showed similar responses to both selective analogs, with 2 nonresponders (expression of other SRIH receptor subtypes) and 2 responders (concomitant expression of SSTR2 and SSTR5) to both analogs. GH release was selectively inhibited by NC-4-28B in 3 adenomas and by BIM-23268 in the remaining 2 adenomas, suggesting predominant expression of SSTR2 and SSTR5, respectively. SRIH failed to inhibit GH release in 7 adenomas (43%). Interestingly, in that group a better inhibitory effect was obtained with BIM-23268 (5 out of 7 adenomas) than with NC-4-28B, suggesting expression of a few SSTR5 receptors only, or of both SSTR2 and SSTR5, respectively. We conclude that the availability of somatostatin analogs selective for SSTR5 will enhance the treatment potency and spectrum in acromegaly.
AB - Somatostatin (SRIH), a cyclic tetradecapeptide hormone originally isolated from mammalian hypothalamus, is a potent suppressor of pituitary growth hormone (GH) secretion. SRIH acts through a family of G-protein-coupled membrane receptors containing seven transmembrane domains. Five genes encoding distinct SRIH receptor (SSTR) subtypes have so far been cloned in human and other species and termed SSTR1-5. In human somatotrophe pituitary adenomas GH secretion is controlled by both SSTR2 and SSTR5. However, in clinical practice only somatostatin analogs selective for SSTR2 (octreotide and lanreotide) are available. This may explain why clinical and in vitro responses to these analogs in acromegaly are only partial. In this study, we investigated the inhibitory effect of two new SRIH analogs with high selectivity for SSTR2 (NC-4-28B) and SSTR5 (BIM-23268) and compared it to that of native somatostatin (SRIH-14) on a large number of GH-secreting adenomas obtained by transphenoidal neurosurgery. Tissues from 16 adenomas were enzymatically dispersed and plated in 24-well dishes at 50,000 cells/well. After 3 days, groups of three wells were incubated for 4 h with medium alone, SRIH-14 or analogs NC-4-28B or BIM-23268, at the concentrations of 0.01, 0.1 and 1 μM. Our results show that 9 out of 16 adenomas were responsive (GH suppression: 20-40% vs. control, p <0.05) to SRIH. In this group only 4 adenomas showed similar responses to both selective analogs, with 2 nonresponders (expression of other SRIH receptor subtypes) and 2 responders (concomitant expression of SSTR2 and SSTR5) to both analogs. GH release was selectively inhibited by NC-4-28B in 3 adenomas and by BIM-23268 in the remaining 2 adenomas, suggesting predominant expression of SSTR2 and SSTR5, respectively. SRIH failed to inhibit GH release in 7 adenomas (43%). Interestingly, in that group a better inhibitory effect was obtained with BIM-23268 (5 out of 7 adenomas) than with NC-4-28B, suggesting expression of a few SSTR5 receptors only, or of both SSTR2 and SSTR5, respectively. We conclude that the availability of somatostatin analogs selective for SSTR5 will enhance the treatment potency and spectrum in acromegaly.
KW - Adenomas
KW - Clinical neuroendocrinology
KW - Growth hormone
KW - Somatostatin
KW - Somatostatin analogs
KW - Somatostatin receptors
UR - http://www.scopus.com/inward/record.url?scp=17844365283&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=17844365283&partnerID=8YFLogxK
U2 - 10.1159/000054651
DO - 10.1159/000054651
M3 - Article
VL - 73
SP - 344
EP - 351
JO - Neuroendocrinology
JF - Neuroendocrinology
SN - 0028-3835
IS - 5
ER -