First-line octreotide-LAR therapy induces tumour shrinkage and controls hormone excess in patients with acromegaly: results from an open, prospective, multicentre trial.

BACKGROUND: The majority of patients with acromegaly have large tumours and the outcome of conventional management remains poor. OBJECTIVE: To investigate the clinical application of octreotide-LAR as primary treatment in newly diagnosed patients with GH-secreting pituitary tumours. DESIGN: Open, prospective, multicentre, 24-week follow-up study. PATIENTS: Thirty-four patients were enrolled (20 men, 14 women; mean age, 50 years); 13 had microadenoma [median tumour volume 327 mm(3) (range 31-629 mm(3))], 21 had macroadenoma [median tumour volume 1,325 mm(3) (range 503-11,583 mm(3))]. Interventions Octreotide-LAR at the dosage of 20 mg every 28 days for the first 12 weeks increased to 30 mg every 28 days to control GH and/or IGF-I excess in 20 patients (64.7%). MAIN OUTCOME MEASURES: Primary endpoints were control of GH (fasting < 2.5 microg/l) and IGF-I secretion (gender- and age-normalized) and presence and entity of tumour mass shrinkage. Secondary endpoint was improvement of symptoms score. RESULTS: In patients with micro- and macroadenomas GH levels decreased to < 2.5 microg/l in 84.6% and 45%, serum IGF-I levels normalized for age and gender in 61.5% and 35% of cases. Failure in achieving either GH < 2.5 microg/l or normal IGF-I levels was found in none of the patients with micro- and in 45% of patients with macroadenoma. Median tumour volume was reduced by 54% (range: -90% to +350%) in micro- and by 49% (range -94% to -14%) in macroadenomas. Headache, perspiration and osteo-arthralgias disappeared in 21%, paresthesias in 38%, fatigue in 26% and carpal tunnel syndrome in 15%. The treatment was well tolerated: more frequent adverse events were gastrointestinal (in 44%). CONCLUSIONS: In both patients with micro- or macroadenoma, primary octreotide-LAR treatment controls hormone excess, induces tumour shrinkage and improves symptoms of acromegaly with limited side effects and can be therefore successfully employed in patients with contraindications for surgery or in those who refuse surgery.

Effect of different therapeutic modalities on spontaneous GH secretion in acromegalic patients.

OBJECTIVES: Three major therapeutic modalities (transsphenoidal surgery, radiotherapy and medical therapy) are currently available for acromegaly. Although surgery is regarded as the primary option, 50--60% of macroadenomas require further treatment in the form of radiotherapy and/or medical therapy. Recent studies have suggested that radiotherapy might damage the normal hypothalamic-pituitary axis and also rarely leads to IGF-I normalization. The aims of this study were: (1) to examine the effect of different therapeutic modalities (transsphenoidal surgery, TSS; radiotherapy, RT; medical treatment with somatostatin analogues, SSA) on the daily spontaneous GH secretory pattern (day curve); and (2) to determine the relationship between the characteristics of the GH secretory pattern and the circulating concentration of IGF-I, acid-labile subunit (ALS) and IGFBP-3. DESIGN AND MEASUREMENTS: Spontaneous GH secretion was evaluated at hourly intervals from 0800 to 1800 h. IGF-I, IGFBP-3 and ALS were measured in basal conditions. The mean and the minimum values obtained from the day curve profile and the coefficient of variation (CV) of single values, which are expressions of the magnitude of the spontaneous secretory pulses, were used for statistical analysis. PATIENTS: In a group of 45 acromegalic patients (28 women, mean age 51 years, range 26--83 years, and 17 men, mean age 57 years, range 37--78 years) treated with different protocols, including TSS, RT and SSA therapy, we evaluated GH secretion to determine the effect of single treatment options on the spontaneous secretory profile. Subjects were grouped on the basis of different therapeutic modalities: TSS+RT+SSA (group 1), TSS+SSA (group 2), SSA (group 3), TSS (group 4), TSS+RT (group 5). In patients treated with somatostatin analogues (SSA), tests were performed about midway between two injections. RESULTS: The number of deficiencies of the other pituitary functions (PD) was significantly higher in the groups that underwent RT (groups 1 and 5) than in the other groups; in both cases, P<0.01. No significant differences were observed with regard to the mean GH, IGF-I, ALS or IGFBP-3 among the different treatment groups. A significant difference in the GH nadir was found between groups 2 and 4 (P=0.042) and between groups 3 and 4 (P=0.015). GH CV showed lower values in subjects who underwent RT (groups 1 and 5) than in the other groups. The difference was statistically significant between group 5 and groups 2, 3 and 4 (P<0.05), between group 1 and groups 3 and 4 (P<0.05), and between groups 2 and 4 (P=0.007). CONCLUSIONS: Our data confirm that radiation therapy decreases GH variability, and that this effect is probably due to hypothalamic damage, as already reported by others. In irradiated patients, a single random sample should therefore be sufficient to evaluate spontaneous GH secretion.

Somatostatin and dopamine receptor expression in lung carcinoma cells and effects of chimeric somatostatin-dopamine molecules on cell proliferation.

To study somatostatin/dopamine (SS/D) synergy in a human cell system constitutively expressing SS and D receptors (SSR and DR, respectively), we characterized the expression of SSR and DR subtypes in the non-small-cell lung cancer line Calu-6, and then we evaluated the effect on cell proliferation of SS/D chimeric molecules (BIM-23A387 and BIM-23A370), which bind with high affinity both sst(2) and D(2)R, and compared the results with those obtained by using SS-14 and subtype-selective SS analogs (SSA) and D agonists (DA). Because Calu-6 cells produce insulin-like growth factor (IGF) and IGF-binding protein (IGFBP) peptides, which play a role in the autocrine/paracrine control of cell growth, we also investigated the effects of chimeric compounds on secretion and expression of IGF system components. Relative high levels of sst(2) and the long isoform of the D(2)R were detected by real-time RT-PCR and Western blot in Calu-6, together with sst(5) and to a lesser extent sst(3) and D(4)R. BIM-23A387 and BIM-23A370 significantly inhibited growth of Calu-6, whereas IGF-IGFBP secretion or expression was unaffected, suggesting a direct inhibitory effect. The inhibition of cell growth, measured by both [(3)H]thymidine incorporation and cell count, was significantly lower when individual SSA and DA control peptides or subtype-specific SSA and DA were tested. BIM-23A370 was more potent than BIM-23A387 (P < 0.001). These findings show that SS/D chimeras can inhibit Calu-6 proliferation in an IGF-independent manner and suggest that this enhanced potency might be because of the induction of SSR/DR dimerization. The Calu-6 cell line, constitutively expressing SSR and DR, provides a suitable model to elucidate the mechanism of action of SSA and DA on regulation of cell growth and to characterize the interaction between SSR and DR.

Efficacy of octreotide-LAR in dieting women with abdominal obesity and polycystic ovary syndrome.

CONTEXT: Somatostatin reduces LH, GH, and insulin, and somatostatin receptors are present at the ovarian level; somatostatin analogs are thus potential candidates for treatment of the polycystic ovary syndrome (PCOS). OBJECTIVE: The purpose of this study was to evaluate the effect of octreotide-LAR, a long-acting somatostatin analog, in anovulatory abdominal obese women with PCOS. DESIGN: A single-blind, placebo-controlled study was performed, lasting for 7 months. SETTING: The patients were ambulatory throughout the study. PATIENTS: Twenty PCOS subjects were enrolled. Eighteen completed the study. INTERVENTIONS: A low-calorie diet was given during the first month, a low-calorie diet plus octreotide-LAR (10 mg; n = 10 subjects) or placebo (n = 10 subjects) was then given, with one im injection every 28 d (for 6 months). MAIN OUTCOME MEASURES: The main outcome measures were clinical features, computerized tomography measurement of fat distribution, androgens, GH, IGF-I, IGF-binding proteins (IGFBPs), fasting and glucose-stimulated insulin, and ovulation. RESULTS: Octreotide had no additional effect in reducing body fat or improving fat distribution than placebo. Conversely, octreotide produced an additional decrease in fasting (P = 0.018) and glucose-stimulated (P = 0.038) insulin levels, an increase in IGFBP-2 (P = 0.042) and IGFBP-3 (P = 0.047), and an improvement in hirsutism (P = 0.004). Moreover, a trend toward greater reductions in testosterone (P = 0.061) and androstenedione (P = 0.069) was observed in women treated with octreotide-LAR compared with those given placebo. All women treated with octreotide ovulated at the end of the study compared with only one of those receiving placebo (P < 0.001). CONCLUSIONS: Octreotide-LAR may be usefully applied to hypocalorically dieting, abdominal obese PCOS women to improve hyperandrogenism and the insulin-IGF-I system. Restoration of ovulatory menstrual cycles appears to be another advantage of this treatment.

Dopamine receptor expression and function in human normal adrenal gland and adrenal tumors.

Dopamine is known to play a role in the modulation of aldosterone and catecholamine secretion from the adrenal gland, where dopamine receptors (DR), in particular the DR type 2 (D(2)), have been found to be expressed. DR expression has also been demonstrated in some types of benign adrenal tumors. The aims of the current study were to evaluate DR expression and D(2) localization in the normal adrenal gland and in different types of benign and malignant adrenal tumors, as well as to evaluate the in vitro effects of the dopamine agonists bromocriptine and cabergoline on hormone secretion in nontumoral adrenal cells. Adrenal tissues from 25 patients, subjected to adrenal surgery for different diseases, were studied. These included three normal adrenals; five adrenal hyperplasias; four aldosterone-secreting, two cortisol-secreting, and two clinically nonfunctioning adrenal adenomas; two aldosterone-secreting, two cortisol-secreting, and two androgen-secreting adrenal carcinomas; and three pheochromocytomas. In all tissues, DR and D(2) isoform (D(2long) and D(2short)) expression was evaluated by RT-PCR. D(2) localization was also evaluated by immunohistochemistry using a specific polyclonal antibody, whereas D(2)-like receptor expression was evaluated by receptor-ligand binding study, using the radiolabeled D(2) analog (125)I-epidepride. The effects of bromocriptine and cabergoline on baseline and ACTH and/or angiotensin II-stimulated aldosterone, cortisol, and androstenedione secretion were evaluated in cell cultures derived from five different adrenal hyperplasia. At RT-PCR, both D(1)-like and D(2)-like receptors were expressed in all normal and hyperplastic adrenals. D(2) and D(4) were expressed in aldosterone- and cortisol-secreting adenomas, cortisol-secreting carcinomas, and clinically nonfunctioning adenomas, whereas no DR was expressed in aldosterone- and androgen-secreting carcinomas. D(2), D(4), and D(5) were expressed in pheochromocytomas. In all D(2)-positive tissues, both D(2) isoforms were expressed, with the exception of one case of aldosterone-secreting adenoma and the cortisol-secreting carcinomas, in which only the D(2long) isoform was expressed. D(2)-like receptor expression was confirmed at receptor-ligand binding study. At immunohistochemistry, D(2) was mainly localized in the zona glomerulosa and reticularis of the adrenal cortex and, to a lesser extent, in the zona fasciculata and medulla of normal and hyperplastic adrenal tissue. In the positive tumors, D(2) was localized in the tumoral cells. At the in vitro study, a significant inhibition of both baseline and ACTH-stimulated aldosterone secretion was found after high-dose cabergoline, but not bromocriptine, administration; and a significant inhibition of angiotensin-II-stimulated aldosterone secretion was found after both bromocriptine and cabergoline administration in the adrenal hyperplasias. In conclusion, the current study demonstrated that both D(1)-like and D(2)-like receptors are expressed in the normal adrenal gland and in a percentage of adrenal adenomas or carcinomas. Bromocriptine and cabergoline induce only a minor inhibition of the secretion of adrenal hormones in the nontumoral adrenal gland in vitro, not excluding, however, the possible effective use of dopamine agonists in vivo in the treatment of adrenal tumors.

Assessment of disease activity in acromegaly by means of a single blood sample: comparison of the 120th minute postglucose value with spontaneous GH secretion and with the IGF system.

OBJECTIVE: It has been suggested that the threshold of 1 micro g/l of GH nadir after glucose load for definition of controlled acromegalic disease proposed in the 2000 consensus statement should be lowered to 0.30. We evaluated these two cut-off values in comparison with IGF-I, ALS and IGFBP-3 in a group of acromegalic patients. With the aim of simplifying the follow-up protocol in these patients we also tested if one single sample taken after glucose load could replace the nadir value. DESIGN AND MEASUREMENTS: GH secretion was evaluated by oral glucose tolerance test (OGTT), and by studying spontaneous secretion (GH day curve) with sampling at hourly intervals from 08.00 to 18.00 h; from the day curve, mean (MGHDC) and minimum (TRGH) values were considered. IGF-I, ALS, and IGFBP-3 were measured in the basal state at the first testing. patients Fifty acromegalic patients (26-83 years, 31 females, 19 males) in various phases of disease activity. Forty-two patients had previously undergone pituitary surgery (10 also radiotherapy), 23 were treated with SMS analogues and three with dopamine agonist drugs. RESULTS: The nadir GH value after glucose load correlated most significantly with the 120th-minute sample (R = 0.95). Comparison of the postglucose 120th minute at the two cut-off values with IGF-I, IGFBP-3 and ALS showed higher concordance of postglucose level at 0.3 with IGF-I, while concordance was similar for the two cut-off values with ALS and IGFBP-3. When the 120th minute postglucose GH value is lower than 1 micro g/l and IGF-I is within 2SD for age nearly all other parameters are normal. IGF-I correlated more with ALS (R = 0.78) than with IGFBP-3 (R = 0.50) and the latter was less concordant with GH secretion parameters than the previous two. CONCLUSIONS: A sample taken at the 120th minute after glucose load, together with IGF-I and/or ALS evaluation can give sufficient information for a routine assessment of disease activity, both in the diagnosis and in the follow-up to treatment. If GH is lower than 1 micro g/l and IGF-I/ALS are normal, then the patient can be classified as 'nonactive' or 'controlled'; a pathological IGF-I and/or ALS value is a sign of disease activity irrespective of the GH values, while normal IGF-I/ALS with an elevated GH requires further assessment.

Potentiating role of IGFBP-2 on IGF-II-stimulated alkaline phosphatase activity in differentiating osteoblasts.

The insulin-like growth factor (IGF) system plays an important role in the autocrine and paracrine regulation of bone formation and remodeling. The aim of this study was to evaluate the role of the autocrine IGF system during osteogenic differentiation in rat tibial osteoblasts (ROB) in culture. In this in vitro model, the stages of osteogenesis studied were S1, corresponding to the onset of alkaline phosphatase (AP) expression (days 0-3); S2, coincident with the peak of AP expression in differentiation culture conditions (days 4-6), and S3, corresponding to the onset of mineral deposition in the extracellular matrix (days 7-9). The results showed that conditioned medium of ROB contains greater amounts of IGF-II than IGF-I at all differentiation stages. Both peptides showed the highest concentrations on day 3 of differentiation (end of S1). All IGF-binding proteins (IGFBPs), except IGFBP-1 and -6, were detected, and IGFBP-2 was the most abundant IGFBP present in the conditioned media, and its degradation increased from S1 to S3. By semiquantitative RT-PCR, IGF-I and IGF-II were highly expressed on days 3 and 6, whereas IGFBP-2 was constantly expressed. We focused our study on the role of IGF-II and IGFBP-2 on the synthesis of AP, an early marker of osteoblast maturation. The results showed that a significant increase in AP expression was induced by IGF-II added to the differentiating osteoblasts continuously or in S1 but not in S2 or S3. IGFBP-2 was able to potentiate endogenous and exogenous IGF-II-dependent stimulation of AP activity, and its proteolytic degradation in late stages of osteogenesis (S2 and S3) was highly correlated with the increase of active matrix metalloproteinase-2 in the CM and with the decreased efficacy of IGF-II action. These data suggest that IGFBP-2, at nearly equimolar concentration with IGF-II, plays a potentiating role in IGF-II action on ROB differentiation in vitro.

Protein turnover, lipolysis, and endogenous hormonal secretion in critically ill children.

OBJECTIVES: The catabolic state is a major contributor to morbidity and mortality of critical illness and may be related to endocrine changes. We studied whether protein and lipid turnover correlate with insulin and growth and thyroid hormone plasma levels in critically ill infants. DESIGN: Prospective clinical study. SETTING: Pediatric intensive care unit. PATIENTS: Twelve critically ill children and ten age-matched controls. MEASUREMENTS: We measured lipolysis and protein turnover by infusing albumin-bound uniformly 13C palmitic acid and 2H3-leucine for 3 hrs and 2H5-glycerol for 5 hrs to critically ill infants. Simultaneously, we measured serum growth hormones, insulin, C-peptide, thyroid-stimulating hormone, T4, T3, albumin, retinol binding protein (RBP), and prealbumin. Hormone and serum protein levels were also measured in six children when recovered from critical illness. Ten healthy age-matched children served as controls for hormone serum levels comparison. RESULTS: Palmitic acid and glycerol turnover were 5.6 +/- 2.2 micromol/kg/min and 12.2 +/- 7.3 micromol/kg/min, respectively, whereas alpha-ketoisocaproic turnover was 4.9 +/- 2.8 micromol/kg/min. Alpha-ketoisocaproic turnover positively correlated (R = 0.7, p = .03) with duration of pediatric intensive care unit admission and with prealbumin and RBP serum levels (R = 0.9, p = .001). Insulin-like growth factor binding protein (IGFBP)-2 was significantly higher and IGFBP-3 was significantly lower in critically ill children (p = .03 and p = .04 vs. recovery phase, respectively). No other hormonal differences were found. Serum albumin was significantly lower in sick children. We found a significant correlation between prealbumin and RBP and IGFBP-3 (R = 0.6, p = 0.03 and R = 0.6, p = .04, respectively). Alpha-ketoisocaproic turnover positively correlated with IGFBP-1 (R = 0.79, p = .01) and did not correlate with insulin-like growth factor I (R = -0.5, p = .15 [not significant]) No other correlations were found. Lipid turnover measurements did not correlate with any endogenous hormone levels or with duration of critical illness. CONCLUSION: Protein turnover but not lipolysis correlated with a persisting critically ill condition, serum prealbumin, RBP, and plasma IGFBP-1.

Effects of growth hormone on leptin metabolism and energy expenditure in hemodialysis patients with protein-calorie malnutrition.

The relationships among growth hormone (GH), leptin, and resting energy expenditure (REE) are not understood. It has been reported that in malnourished hemodialysis patients, GH increases muscle protein synthesis, a process that requires energy. The present study evaluated the arterial levels and the forearm exchange of leptin, as well as the REE of the same patients during their participation in the same study, in four sequential 6-wk periods: I, baseline; II, GH treatment; III, washout; and IV, GH + intradialytic parenteral nutrition. During periods II and IV, patients received GH (5 mg three times per week). REE rose by 5% in period II, declined during period III, and rose by 7% during period IV. Basal leptin levels were low (2.0 +/- 0.19 ng/L). Insulin and leptin levels, as well as leptin release from the forearm, were unchanged during periods I through III but rose (+ 36%; P: < 0.05) during period IV. Changes in arterial leptin were directly related to changes in forearm leptin release (P: < 0.002), indicating a role of leptin production by peripheral tissues on leptinemia. Changes in leptin release were directly related to insulin (P: < 0.001) and, less consistently, to insulin-like growth factor-binding protein-1 levels (P: < 0.02). Similarly, variations in leptin levels were directly related to insulin (P: < 0.01). Variations in REE were not related to variations in leptin or insulin levels but to changes in muscle protein synthesis (P: < 0.025). The data show that in malnourished hemodialysis patients, treatment with GH is not invariably associated with an increase in leptin production. An increase in leptin release by peripheral tissues and leptin levels occurs only in the setting of hyperinsulinemia. The increase in REE that is induced by treatment with GH is not dependent on changes in leptin but is largely accounted for by the energy cost of the stimulation of muscle protein synthesis.