Alterations of the 11p15 imprinted region and the IGFs system in a case of recurrent non-islet-cell tumour hypoglycaemia (NICTH).
OBJECTIVE
Non-islet-cell tumour hypoglycaemia (NICTH) is a rare disorder and has been explained by oversecretion of non mature IGF-II and dysregulation of the IGFs sytem. The mechanisms responsible for tumoural IGF-II overexpression in NICTH have been rarely studied. We report an extensive study of IGF-II and IGFBPs as well as chromosome 11p15 gene expression regulation in a case of a pleural fibrosarcoma in a 63-year-old patient presenting with NICTH.


RESULTS
Abnormal high molecular weight precusor forms of IGF-II were present in the patient's serum and were associated with dramatic alterations in the circulating levels of IGF-I, IGF-II and their binding proteins, as well as an inhibition of the somatotroph axis. These alterations returned to normal following complete surgical removal of the tumour. No structural change in chromosome 11p15 region was apparent in the tumour. However, dysregulation of this imprinted region was demonstrated, leading to the loss of imprinting of the IGF-II gene associated with high IGF-II expression, and by contrast decreased level of expression of H19 and p57KIP2 genes. Recurrence of the tumour four years latter was not associated with hypoglycaemia or changes in the levels of circulating IGFs or IGFBPs, despite IGF-II overexpression by the tumour. This suggests that a large tumour volume is required to reach high enough levels to cause changes in the levels of circulating IGFs and IGFBPs, and to cause hypoglycaemia.


CONCLUSIONS
These results suggest that a dysregulation of gene expression and imprinting of chromosome 11p15 region is associated with tumour growth and IGF-II overexpression in non-islet-cell tumour hypoglycaemia.
Clinique des Maladies Endocriniennes et Métaboliques; CNRS UPR 1524, Hôpital Cochin, Université René-Descartes,; Laboratoire d'Explorations Fonctionnelles Endocriniennes, Hôpital Armand-Trousseau, Paris, France. Bertherat@icgm.cochin.inserm.fr
J
J
Bertherat
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A
Logié
C
C
Gicquel
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F
Mourriéras
J P
JP
Luton
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Y
Le Bouc
D015139:Blotting, Southern; D015153:Blotting, Western; D002880:Chromosomes, Human, Pair 11; D005354:Fibrosarcoma / Q000737:chemistry / Q000150:complications / Q000235:genetics*; D018392:Genomic Imprinting; D006801:Humans; D007003:Hypoglycemia / Q000209:etiology / Q000235:genetics* / Q000378:metabolism; D007335:Insulin-Like Growth Factor II / Q000032:analysis / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000737:chemistry / Q000235:genetics*; D010997:Pleural Neoplasms / Q000737:chemistry / Q000150:complications / Q000235:genetics*; D012313:RNA / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction
D012313:RNA; D007335:Insulin-Like Growth Factor II