EXPRESSION OF MENIN IN THE HUMAN THYROID GLAND.

INTRODUCTION: The expression of menin in the thyroid gland has long been debated. Animal models with targeted inactivation of menin in the thyroid gland have shown that its inactivation might play a role in the progression to a more aggressive type of cancer. Human studies are conflicting, some have identified mutations in the MEN1 gene in a sub-type of oncocytic thyroid carcinomas, while others have not identified a higher prevalence of thyroid cancer in MEN1 patients. OBJECTIVE: To analyze the immunohistochemical expression of menin in different types of thyroid carcinomas. MATERIALS AND METHODS: 48 thyroid tumours (12 papillary thyroid carcinomas (PTC), 6 anaplastic thyroid carcinomas (ATC), 12 poorly differentiated thyroid carcinomas (PDTC), 5 medullary thyroid carcinomas (MTC), 5 oncocytic follicular carcinomas (OC), 3 oncocytic adenomas (OA) and 5 goiters (G)) were tested for nuclear expression of menin using an anti-menin antibody. The expression was considered positive, negative or decreased. RESULTS: The expression of menin was positive, identical to normal tissue, in 39 cases (81.25%). The expression was decreased (n=8) or absent (n=1) in 9 tumours (18.75% - 2 PTC, 5 PDTC, 2 OC) accounting for 42% (5/12) of the PDTC and 40% (2/5) of the OC. CONCLUSIONS: Our results show that the expression of menin is generally preserved in human thyroid carcinomas, but it can be decreased or absent in certain types of thyroid cancer. Further molecular studies are needed to evaluate to potential of menin protein in tumorigenesis.

O6-Methylguanine-DNA methyltransferase status in neuroendocrine tumours: prognostic relevance and association with response to alkylating agents.

BACKGROUND: O(6)-Methylguanine-DNA methyltransferase (MGMT) loss of expression has been suggested to be predictive of response to temozolomide in neuroendocrine tumours (NETs), but so far, only limited data are available. We evaluated the prognostic and predictive value of MGMT status, assessed by two molecular methods and immunohistochemistry, in a large series of NETs of different origins. METHODS: A total of 107 patients, including 53 treated by alkylants (temozolomide, dacarbazine or streptozotocin), were retrospectively studied. In each case, we used methyl-specific PCR (MS-PCR) and pyrosequencing for evaluation of promoter methylation and immunohistochemistry for evaluation of protein status. RESULTS: MGMT promoter methylation was detected in 12 out of 99 (12%) interpretable cases by MS-PCR and in 24 out of 99 (24%) by pyrosequencing. O(6)-Methylguanine-DNA methyltransferase loss of expression was observed in 29 out of 89 (33%) interpretable cases. Status of MGMT was not correlated with overall survival (OS) from diagnosis. Progression-free survival and OS from first alkylant use (temozolomide, dacarbazine and streptozotocin) were higher in patients with MGMT protein loss (respectively, 20.2 vs 7.6 months, P<0.001 and 105 vs 34 months, P=0.006) or MGMT promoter methylation assessed by pyrosequencing (respectively, 26.4 vs 10.8 months, P=0.002 and 77 vs 43 months, P=0.026). CONCLUSIONS: Our results suggest that MGMT status is associated with response to alkylant-based chemotherapy in NETs.

Non-classical antiestrogenic actions of dexamethasone in variant MCF-7 human breast cancer cells in culture.

The aim of this work was to determine whether dexamethasone (Dex), a synthetic glucocorticoid, counteracts the stimulatory effects of estradiol (E2) on MCF-7 cells. We have shown that Dex inhibits in a dose-dependent fashion the estradiol-stimulated cell proliferation. This inhibition (ID50 congruent to 5-10 nM), which is complete at 100 nM Dex, is prevented by the antiglucocorticoid RU 486 and is clearly different from that found with trans-4-OH-tamoxifen because the inhibition due to a fixed concentration of Dex is not abolished by a high concentration of estradiol. This inhibitory effect displays some degree of specificity. Progesterone and the progestins R 5020 and ORG 2058 are without effect and Dex does not alter the triiodo-L-thyronine-stimulated cell growth. To characterize further the antiestrogenic action of Dex, the effects of this drug on specific responses to estradiol were studied. (1) Among the positive responses to estradiol two are prevented by Dex (the increase of concentration of progestin receptors and that of immunoreactive insulin-like growth factor I, IR-IGF-I, in conditioned medium) and two are insensitive to Dex (the enhancement of the secretion of 52,000 and 160,000 Mr proteins). (2) A negative response to estradiol (the down-regulation of estrogen receptor) is not prevented but rather accentuated by Dex. Thus, Dex counteracts the stimulatory effects of estradiol on the proliferation of MCF-7 cell variants characterized by progestin insensitivity. This non-classical antiestrogenic effect could be due in part to the attenuation of the E2-induced IR-IGF-I secretion and, less probably, to the accentuation of the down-regulation of E2 receptors. It could account for certain therapeutic and/or side effects of glucocorticoids on estrogen target cells.

Serum interleukin-6 levels in adult acute myelogenous leukemia: relationship with disease characteristics and outcome.

Serum interleukin-6 (IL-6) levels were measured in 58 adult patients with newly diagnosed acute myelogenous leukemia (AML) using an ELISA method in order to find potential clinical correlations. Detectable average levels were 57 +/- 68 pg/ml and 52 patients (90%) had higher cytokine levels than normal donors. IL-6 levels (115 +/- 102 pg/ml versus 36 +/- 40 pg/ml, p = 0.0001) were higher in patients with fever of apparently non infectious origin, and higher levels were associated with higher percentage of blasts in the peripheral blood (R = 0.29, p = 0.04) and in the bone marrow (R = 0.39, p = 0.003), elevated serum LDH level (R = 0.36, p = 0.01), hyperbilirubinemia (R = 0.36, p = 0.008), elevated serum GGT level (R = 0.46, p = 0.003), and elevated serum GOT (R = 0.36, p = 0.008) and GPT levels (R = 0.44, p = 0.004). Highest IL-6 levels were observed in FAB M1 (86 +/- 112 pg/ml), M3 (73 +/- 69 pg/ml), and M6 (92 +/- 60 pg/ml) AML subtypes. Serum IL-6 levels in AML might be related to both non specific inflammatory reactions and the specific biology of the disease.

Heterogeneity of human prolactin. Influence on immunoassays (RIA and IRMA).

Plasma hPRL consists of a complex mixture of molecular forms. The monomeric form, derived from the pituitary, is the main form. Others (dimeric or oligomeric) can form de novo in plasma. Recently, BBPRL (big big PRL) has been identified in some cases as an antiPRL autoantibody, but these data require further investigation. The PRL forms are differently recognized by immunoassays (IRMA and RIA) and are a source of inter-assay discrepancy.

Effects of recombinant growth factors on energy expenditure in maintenance hemodialysis patients.

We compared the metabolic effects of recombinant human (rh) insulin-like growth factor (IGF)-1 or a combination of rhIGF-1 + rh growth hormone (GH) on resting energy expenditure (REE) in 8 maintenance hemodialysis (MHD) patients. Seven males and 1 female (aged 41.6 +/- (SD) 12.4) with no evidence of malnutrition (BMI 21.6 +/- 2.2 kg/m2, serum albumin 45 +/- 2 g/l, serum IGF-1 359 +/- 165 microg/l) received either rhIGF-1 (80 microg/kg/day) or rhIGF-1 (80 microg/kg/day) + rhGH (50 microg/kg/day) for 3 days in a random crossover design. REE and the respiratory quotient (RQ) were measured at rest before and after the 3-day treatment. The results confirmed that MHD patients have a REE not different from normal individuals. REE was strongly correlated with lean body mass but not with fat mass. rhIGF-1 treatment did not modify REE despite doubling serum IGF-1 values, whereas a combined rhIGF1 + rhGH treatment significantly increased REE by 11% (p < 0.001). There was no change in RQ under both treatments, in response to a proportionate increase in VCO2 and VO2. These results show that energy expenditure is mainly dependent upon lean body mass in well-nourished MHD patients. The metabolic effects of rhIGF-1 and rhGH on energy expenditure may differ in response to their opposite effects on lipid oxidation and insulin regulation.

Haemodialysis with the biocompatible high permeability AN-69 membrane does not alter plasma insulin-like growth factor-I and insulin-like growth factor binding protein-3.

BACKGROUND: Insulin-like growth factor-I (IGF-I) bioactivity has been reported to be decreased in maintenance haemodialysis patients and this may affect their nutritional status. Clearances of IGF-I and its binding proteins (IGFBPs) during haemodialysis sessions using a high permeability biocompatible membrane are unknown. METHODS: Five well nourished, non-diabetic adult patients were studied during one 4-h morning haemodialysis treatment using the high permeability biocompatible AN-69 dialyser. Blood was collected at the arterial and venous ports of the dialyser at 0, 1, 2 and 4 h of dialysis for haematocrit, plasma IGF-I, IGFBP-3 and insulin measurements. IGF-I, IGFBP-3 and insulin concentrations were adjusted for haemoconcentration before comparisons were made. RESULTS: At the beginning of the dialysis session, plasma IGF-I, IGFBP-3 and insulin levels were within the normal range (297 +/- 47 ng/ml (mean+/-SEM), 4.3 +/- 0.6 microg/ml and 11.8 +/- 3.4 microIU/ml, respectively). During the session, insulin tended to be cleared through the dialyser, whereas plasma IGF-I and IGFBP-3 values did not vary significantly. CONCLUSION: Dialysis with the high permeability AN69 membrane did not alter the main blood compounds of the IGF system in well nourished chronic haemodialysis patients, and it is unlikely that the malnutrition frequently observed in such patients would result from alterations of the IGF system during haemodialysis.

Increase of circulating insulin-like growth factor-I in chronic renal failure is reduced by low-protein diet.

We performed a nutritional trial to assess the variations of circulating insulin-like growth factor-I (IGF-I) in chronic renal failure (CRF). Eight patients suffering from mild renal failure (SCr = 374 +/- 52 mumol/l) were prescribed a standard diet for 1 month followed by 1 month of protein restriction. Mean protein intake was 0.77 and 0.46 g/kg BW/day, mean caloric intake 25 and 24.7 kcal/kg BW/day for the first and the second month, respectively. After each period of diet, nitrogen balances were negative (-1.2 +/- 1.6 and -1.6 +/- 0.9 g/N/day). Despite these low-caloric conditions, mean serum IGF-I level was at the upper level of normal (358 +/- 136 ng/ml) after 1 month of standard protein intake, and statistically reduced (289 +/- 122 ng/ml, p < 0.002) by the low-protein diet. No correlation was observed between serum IGF-I levels and protein, caloric intake, and nitrogen balances for the two periods. Estimation of the IGF-I binding by the ratio of extracted to nonextracted IGF-I value suggested abnormal binding in CRF. This binding was modified by reduced protein intake. In conclusion, larger studies are needed in CRF to assess the significance of IGF-I variations and the IGF-I binding proteins which modulate the bioactivity of this growth factor.

Insulin-like growth factor-1 and its binding proteins during a low-protein diet in chronic renal failure.

The effects of a low-protein diet on the serum insulin-like growth factor (IGF)-1 and IGF binding proteins (IGFBP) were investigated during a 3-month controlled study in 12 adult chronic renal failure patients. Six patients were randomly supplemented with keto acids (Cetolog, Clintec, Velizy, France). Protein intake was prescribed so that both groups were isonitrogenous. Dietary survey included a monthly 3-day food record and a 24-h urinary urea measurement. After a 4- to 6-wk equilibrium period (1.11 g of protein, 32 kcal/kg body wt per day), patients reduced their protein intake to 0.71 g protein/kg body wt per day. Energy intake was kept constant (31 kcal/kg body wt per day) during the 3-month period. Serum IGF-1 levels were in normal range and, for 11 of the 12 patients, were correlated with the GFR (P = 0.01). These serum IGF-1 values did not decrease after reducing the protein intake. By Western ligand blotting, serum IGFBP1, IGFBP2, and IGFBP4 levels were significantly higher than normal adults, whereas the IGFBP3 level was not increased. IGFBP were not modified when protein intake was reduced. The IGFBP1 level was elevated despite a normal insulin level. IGFBP4 changes were inversely correlated with IGF-1 variations. There was no difference between groups receiving or not receiving the keto acids. Thus, in adult chronic renal failure, reducing protein intake by 40% did not modify the growth hormone/IGF-1/IGFBP axis.

Acute leptin regulation in end-stage renal failure: the role of growth hormone and IGF-1.

BACKGROUND: Leptin, a recently discovered peptide involved in nutrient intake and energy expenditure, has been shown to be abnormally regulated in certain conditions such as obesity. In chronic renal failure, leptin appears to be increased. However, little is known about leptin regulation during chronic renal failure (CRF). METHODS: We measured serum leptin in eight well nourished, chronic hemodialysis patients (seven males, one female) receiving anabolic factors for three days as either recombinant insulin-like growth factor-1 (rhIGF-1) or a combination of recombinant growth hormone (rhGH) plus recombinant IGF-1, in a random cross-over trial. RESULTS: Serum leptin values were in the range of normal volunteers matched for body mass index. As reported in other conditions, serum leptin was strongly correlated with patients dry body wt (P = 0.01) and body fat (P = 0.0001). Both treatments affected serum leptin in a rapid and opposite manner. RhIGF-1 decreased serum leptin from 11.2+/-20.8 (SD) to 4.3+/-3.8 microg/liter (P = 0.011), whereas the combination of rhGH + rhIGF-1 increased serum leptin from 7.4+/-9.4 to 21.0+/-32.9 microg/liter (P = 0.011). Regression analyses indicated a linear regression between serum leptin and insulin variations after treatment. CONCLUSIONS: This study shows for the first time that both rhIGF-1 and rhGH acutely regulate serum leptin in dialysis patients. Whether leptin changes are explained by the concomitant insulin variation should be further studied under renal failure conditions.

Evolution of GH secretion in urine during an in-patient slimming course in obese children.

OBJECTIVE: To estimate the change in GH excretion in urine (GH-U) during a slimming course, and if increased, to assess the components of the course related to the increase in obese children. DESIGN: Observational follow-up study of patients admitted for primary obesity to an in-patient slimming course lasting at least 10 weeks. SUBJECTS: 48 complete observations out of 54 consecutive pre-pubertal patients admitted to a paediatric centre for treatment of primary obesity (BMI greater than the 90th percentile of the national reference curves). MEASUREMENTS: GH excretion in urine by immunoradiometric assay, at entry and after 10 weeks, various anthropometric measurements, nutritional intake and departure from the prescribed diet, time spent in physical activity, sleep duration. RESULTS: A mean decrease of 0.90 standard deviations for BMI was accompanied by a 34% increase of GH-U. Time spent in physical activity was the only component of the course found to be related to the magnitude of GH-U increase. CONCLUSION: The results of this observational study confirm that GH-U is increased after a slimming course in children, and suggest that physical activity is a major contributor to the restoration of normal GH-U levels.

Assay of growth hormone levels in human plasma using commercial kits: analysis of some factors influencing the results.

The reliability of growth hormone (GH) assays, performed in 39 different laboratories, using five different immunoassay kits was evaluated. It was found that the variability in GH levels measured by different commercial assay kits may be due to human factors, as well as differences between the kits. The influence of the variation in amount of circulating GH, during provocative testing and spontaneous secretory episodes, on the results of GH assay was also evaluated. It was found that large molecular weight forms of GH may be underestimated by some assay kits.