Primary pigmented nodular adrenocortical disease reveals insulin-like growth factor binding protein-2 regulation by protein kinase A.
OBJECTIVE
Primary pigmented nodular adrenocortical disease (PPNAD) can occur as an isolated trait or part of Carney complex, a familial lentiginosis-multiple endocrine neoplasia syndrome frequently caused by mutations in PRKAR1A, which encodes the 1alpha regulatory subunit of protein kinase A (PKA). Because alterations in the insulin-like growth factor (IGF) axis, particularly IGF-II and IGF binding protein (IGFBP)-2 overexpression, have been implicated in sporadic adrenocortical tumors, we sought to examine the IGF axis in PPNAD.


METHODS
RNA samples and paraffin-embedded sections were procured from adrenalectomy specimens of patients with PPNAD. Changes in expression of IGF axis components were evaluated by real-time quantitative RT-PCR and immunohistochemistry. NCI-H295R cells were used to study PKA and IGF axis signaling in adrenocortical cells in vitro.


RESULTS
IGFBP-2 mRNA level distinguished between the two genetic subtypes of this disease; increased IGFBP-2 expression in PRKAR1A mutation-positive PPNAD tissues was also confirmed by immunohistochemistry. Moreover, PKA inhibitors increased IGFBP-2 expression in NCI-H295R adrenocortical cells, and anti-IGFBP-2 antibody reduced their proliferation.


CONCLUSIONS
IGFBP-2 expression is increased in PPNAD caused by PRKAR1A mutations, and in adrenocortical cancer cells. This is the first evidence for PKA-dependent regulation of IGFBP-2 expression in adrenocortical cells.
Shi
Zonggao
Z
Division of Pediatric Endocrinology, University of Pennsylvania School of Medicine, The Children's Hospital of Philadelphia, Abramson Research Center, Philadelphia, PA 19104-4318, USA.
Henwood
Maria J
MJ
Bannerman
Peter
P
Batista
Dalia
D
Horvath
Anelia
A
Guttenberg
Marta
M
Stratakis
Constantine A
CA
Grimberg
Adda
A
D000306:Adrenal Cortex Neoplasms / Q000201:enzymology* / Q000235:genetics; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D054756:Cyclic AMP-Dependent Protein Kinase RIalpha Subunit; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D006801:Humans; D007150:Immunohistochemistry; D018971:Insulin-Like Growth Factor Binding Protein 2 / Q000032:analysis / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007335:Insulin-Like Growth Factor II / Q000378:metabolism; D009377:Multiple Endocrine Neoplasia / Q000201:enzymology* / Q000235:genetics; D009154:Mutation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
D054756:Cyclic AMP-Dependent Protein Kinase RIalpha Subunit; D018971:Insulin-Like Growth Factor Binding Protein 2; C517834:PRKAR1A protein, human; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D007335:Insulin-Like Growth Factor II; D017868:Cyclic AMP-Dependent Protein Kinases