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Title: Rearrangements at the 11p15 locus and overexpression of insulin-like growth factor-II gene in sporadic adrenocortical tumors

Abstract

Little is known about the pathophysiology of sporadic adrenocortical tumors in adults. Because loss of heterozygosity at the 11p15 locus has been described in childhood tumors, particularly in adrenocortical tumors associated with the Beckwith-Wiedemann syndrome, and because insulin-like growth factor-II (IGF-II) is a crucial regulator of fetal adrenal growth, the authors looked for structural analysis at the 11p15 locus and IGF-II gene expression in 23 sporadic adrenocortical adult tumors: 6 carcinomas (5 with Cushing`s syndrome and 1 nonsecreting) and 17 benign adenomas (13 with Cushing`s syndrome, 1 pure androgen secreting, and 3 nonsecreting). Twenty-one patients were informative at the 11p15 locus, and six (four carcinomas and two adenomas) of them (28.5%) exhibited 11p15 structural abnormalities in tumor DNA (five, a uniparental disomy and one, a mosaicism). In a single case that could be further studied, a paternal isodisomy was observed. Very high IGF-II mRNA contents were detected in seven tumors (30%; 5 of the 6 carcinomas and 2 of the 17 adenomas). They were particularly found in tumors with uniparental disomy at the 11p15 locus. Overall, a strong correlation existed between IGF-II mRNA contents and DNA demethylation at the IGF-II locus. These data show that genetic alterations involving the 11p15more » locus were highly frequent in malignant tumors, but found only in rare adenomas. These results in combination with evidence for overexpression of IGF-II from the 11p15.5 locus suggest that abnormalities in structure and/or expression of the IGF-II gene play a role as a late event of a multistep process of tumorigenesis. 58 refs., 6 figs., 4 tabs.« less

Authors:
; ;  [1]; ; ; ;  [2]
  1. Hopital Trousseau, Paris (France)
  2. Hopital Cochin, Paris (France)
Publication Date:
OSTI Identifier:
54468
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Clinical Endocrinology and Metabolism; Journal Volume: 78; Journal Issue: 6; Other Information: PBD: Jun 1994
Country of Publication:
United States
Language:
English
Subject:
55 BIOLOGY AND MEDICINE, BASIC STUDIES; ADRENAL GLANDS; NEOPLASMS; HUMAN CHROMOSOMES; CHROMOSOMAL ABERRATIONS

Citation Formats

Gicquel, C., Schneid, H., Le Bouc, Y., Bertagna, X., Francillard-Leblond, M., Luton, J.P., and Girard, F.. Rearrangements at the 11p15 locus and overexpression of insulin-like growth factor-II gene in sporadic adrenocortical tumors. United States: N. p., 1994. Web. doi:10.1210/jc.78.6.1444.
Gicquel, C., Schneid, H., Le Bouc, Y., Bertagna, X., Francillard-Leblond, M., Luton, J.P., & Girard, F.. Rearrangements at the 11p15 locus and overexpression of insulin-like growth factor-II gene in sporadic adrenocortical tumors. United States. doi:10.1210/jc.78.6.1444.
Gicquel, C., Schneid, H., Le Bouc, Y., Bertagna, X., Francillard-Leblond, M., Luton, J.P., and Girard, F.. Wed . "Rearrangements at the 11p15 locus and overexpression of insulin-like growth factor-II gene in sporadic adrenocortical tumors". United States. doi:10.1210/jc.78.6.1444.
@article{osti_54468,
title = {Rearrangements at the 11p15 locus and overexpression of insulin-like growth factor-II gene in sporadic adrenocortical tumors},
author = {Gicquel, C. and Schneid, H. and Le Bouc, Y. and Bertagna, X. and Francillard-Leblond, M. and Luton, J.P. and Girard, F.},
abstractNote = {Little is known about the pathophysiology of sporadic adrenocortical tumors in adults. Because loss of heterozygosity at the 11p15 locus has been described in childhood tumors, particularly in adrenocortical tumors associated with the Beckwith-Wiedemann syndrome, and because insulin-like growth factor-II (IGF-II) is a crucial regulator of fetal adrenal growth, the authors looked for structural analysis at the 11p15 locus and IGF-II gene expression in 23 sporadic adrenocortical adult tumors: 6 carcinomas (5 with Cushing`s syndrome and 1 nonsecreting) and 17 benign adenomas (13 with Cushing`s syndrome, 1 pure androgen secreting, and 3 nonsecreting). Twenty-one patients were informative at the 11p15 locus, and six (four carcinomas and two adenomas) of them (28.5%) exhibited 11p15 structural abnormalities in tumor DNA (five, a uniparental disomy and one, a mosaicism). In a single case that could be further studied, a paternal isodisomy was observed. Very high IGF-II mRNA contents were detected in seven tumors (30%; 5 of the 6 carcinomas and 2 of the 17 adenomas). They were particularly found in tumors with uniparental disomy at the 11p15 locus. Overall, a strong correlation existed between IGF-II mRNA contents and DNA demethylation at the IGF-II locus. These data show that genetic alterations involving the 11p15 locus were highly frequent in malignant tumors, but found only in rare adenomas. These results in combination with evidence for overexpression of IGF-II from the 11p15.5 locus suggest that abnormalities in structure and/or expression of the IGF-II gene play a role as a late event of a multistep process of tumorigenesis. 58 refs., 6 figs., 4 tabs.},
doi = {10.1210/jc.78.6.1444},
journal = {Journal of Clinical Endocrinology and Metabolism},
number = 6,
volume = 78,
place = {United States},
year = {Wed Jun 01 00:00:00 EDT 1994},
month = {Wed Jun 01 00:00:00 EDT 1994}
}
  • The photoactive insulin-like growth factor (IGF)-II analogue 4-azidobenzoyl- SVI-IGF-II was synthesized and used to label specifically and covalently the Mr = 250,000 Type II IGF receptor. When rat adipocytes are irradiated after a 10-min incubation with 4-azidobenzoyl- SVI-IGF-II at 10 degrees C and immediately homogenized, most of the labeled IGF-II receptors are associated with the plasma membrane fraction, indicating that receptors accessible to the labeling reagent at low temperature are on the cell surface. However, when the photolabeled cells are incubated at 37 degrees C for various times before homogenization, labeled IGF-II receptors are rapidly internalized with a half-time ofmore » 3.5 min as evidenced by a loss from the plasma membrane fraction and a concomitant appearance in the low density microsome fraction. The steady state level of cell surface IGF-II receptors in the presence or absence of IGF-II remains constant under these conditions, demonstrating that IGF-II receptors rapidly recycle back to the cell surface at the same rate as receptor internalization. Using the above methodology, it is shown that acute insulin action: 1) increases the steady state number of cell surface IGF-II receptors; 2) increases the number of ligand-bound IGF-II receptors that are internalized per unit of time; and 3) increases the rate of cellular SVI-IGF-II degradation by a process that is blocked by anti-IGF-II receptor antibody.« less
  • Two forms of insulin-like growth factor (IGF) II with molecular masses of 10 and 7.5 kDa, respectively, were found in tumor tissue from human adrenal pheochromocytomas. The tumors contained 5.3-7.1 ..mu..g of immunoreactive IGF-II per g of tissue, which is about 20 times more than in adrenal medulla. The total bioactive IGF measured by radioimmunoassay in the pheochromocytomas exceeded that in normal liver or kidney, which contained only the 7.5-kDa IGF-II species, by a factor of approx.100. By contrast, the amount of IGF-I was just measurable and did not vary significantly between tumor and normal tissue. The high amounts ofmore » IGF-II in the pheochromocytomas were not reflected, however, by a corresponding increase of mRNA. The opposite situations was found in Wilms tumors, where IGF-II content was in the same range as in nontumor tissues despite increased expression of IGF-II mRNA.« less
  • The authors reported that serum and tumor from a hypoglycemic patient with a fibrosarcoma contained insulin-like growth factor II (IGF-II), mostly in a large molecular form designated big IGF-II. They now describe two additional patients with non-islet-cell tumor with hypoglycemia (NICTH) whose sera contained big IGF-II. Removal of the tumor eliminated most of the big IGF-II from the sera of two patients. Because specific IGF-binding proteins modify the bioactivity of IGFs, the sizes of the endogenous IGF-binding protein complexes were determined after neutral gel filtration through Sephadex G-200. Normally about 75% of IGFs are carried as a ternary complex ofmore » 150 kDa consisting of IGF, a growth hormone (GH)-dependent IGF-binding protein, and an acid-labile complexing component. The three patients with NICTH completely lacked the 150-kDa complex. IGF-II was present as a 60-kDa complex with variable contributions of smaller complexes. In the immediate postoperative period, a 110-kDa complex appeared rather than the expected 150-kDa complex. Abnormal IGF-II binding may be important in NICTH because the 150-kDa complexes cross the capillary membrane poorly. The smaller complexes present in our patients' sera would be expected to enter interstitial fluid readily, and a 4- to 5-fold increase in the fraction of IGFs reaching the target cells would result.« less
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  • Insulinlike growth factor I (IGF-I) is a mitogenic hormone with important regulatory roles in growth and development. One of the target organs for IGF-I action is the kidney, which synthesizes abundant IGF-I receptors and IGF-I itself. To study the involvement of IGF-I and the IGF-I receptor in the development of nephropathy, one of the major complications of diabetes mellitus, we measured the expression of these genes in the kidney and in other tissues of the streptozocin-induced diabetic rat. The binding of 125I-labeled IGF-I to crude membranes was measured in the same tissues. We observed a 2.5-fold increase in the steady-statemore » level of IGF-I-receptor mRNA in the diabetic kidney, which was accompanied by a 2.3-fold increase in IGF-I binding. In addition to this increase in IGF-I binding to the IGF-I receptor, there was also binding to a lower-molecular-weight material that may represent an IGF-binding protein. No change was detected in the level of IGF-I-peptide mRNA. Similarly, IGF-II-receptor mRNA levels and IGF-II binding were significantly increased in the diabetic kidney. IGF-I- and IGF-II-receptor mRNA levels and IGF-I and IGF-II binding returned to control values after insulin treatment. Because the IGF-I receptor is able to transduce mitogenic signals on activation of its tyrosine kinase domain, we hypothesize that, among other factors, high levels of receptor in the diabetic kidney may also be involved in the development of diabetic nephropathy. Increased IGF-II-receptor expression in the diabetic kidney may be important for the intracellular transport and packaging of lysosomal enzymes, although a role for this receptor in signal transduction cannot be excluded. Finally, the possible role of IGF-binding proteins requires further study.« less