Abstract |
Pregnancy-associated plasma protein-A ( PAPP-A) stimulates insulin-like growth factor (IGF) action through proteolysis of IGF-binding protein (IGFBP)-4. In experimental animals, PAPP-A accelerates ovarian tumor growth by this mechanism. To investigate the effect of PAPP-A in humans, we compared serum and ascites from 22 women with ovarian carcinoma. We found that ascites contained 46-fold higher PAPP-A levels as compared to serum (P < 0.001). The majority (80%) of PAPP-A was enzymatically active. This is supported by the finding that ascites contained more cleaved than intact IGFBP-4 (P < 0.03). Ascites was more potent than serum in activating the IGF-I receptor (IGF-IR) in vitro (+31%, P < 0.05); in 8 of 22 patients by more than two-fold. In contrast, ascites contained similar levels of immunoreactive IGF-I, and lower levels of IGF-II (P < 0.001). Immunohistochemistry demonstrated the presence of IGF-IR in all but one tumor, whereas all tumors expressed PAPP-A, IGFBP-4, IGF-I and IGF-II. Addition of recombinant PAPP-A to ascites increased the cleavage of IGFBP-4 and enhanced IGF-IR activation (P < 0.05). In conclusion, human ovarian tumors express PAPP-A, IGFBP-4 and IGFs and these proteins are also present in ascites. We suggest that both soluble PAPP-A in ascites and tissue-associated PAPP-A serve to increase IGF bioactivity and, thereby, to stimulate IGF-IR-mediated tumor growth.
|
Authors | Jacob Thomsen, Rikke Hjortebjerg, Ulrick Espelund, Gitte Ørtoft, Poul Vestergaard, Nils E Magnusson, Cheryl A Conover, Trine Tramm, Henrik Hager, Claus Høgdall, Estrid Høgdall, Claus Oxvig, Jan Frystyk |
Journal | Oncotarget
(Oncotarget)
Vol. 6
Issue 31
Pg. 32266-78
(Oct 13 2015)
ISSN: 1949-2553 [Electronic] United States |
PMID | 26336825
(Publication Type: Journal Article, Multicenter Study, Research Support, Non-U.S. Gov't)
|
Chemical References |
- IGF1 protein, human
- IGF1R protein, human
- IGF2 protein, human
- Insulin-Like Growth Factor Binding Protein 4
- Receptors, Somatomedin
- Insulin-Like Growth Factor I
- Insulin-Like Growth Factor II
- Receptor, IGF Type 1
- Pregnancy-Associated Plasma Protein-A
- PAPPA protein, human
|
Topics |
- Aged
- Ascitic Fluid
(enzymology)
- Carcinoma
(enzymology)
- Case-Control Studies
- Denmark
- Female
- HEK293 Cells
- Humans
- Insulin-Like Growth Factor Binding Protein 4
(metabolism)
- Insulin-Like Growth Factor I
(metabolism)
- Insulin-Like Growth Factor II
(metabolism)
- Middle Aged
- Ovarian Neoplasms
(enzymology)
- Pregnancy-Associated Plasma Protein-A
(metabolism)
- Receptor, IGF Type 1
- Receptors, Somatomedin
(genetics, metabolism)
- Signal Transduction
- Transfection
- Up-Regulation
|