Prostaglandin E2 mediates phosphorylation and down-regulation of the tuberous sclerosis-2 tumor suppressor (tuberin) in human endometrial adenocarcinoma cells via the Akt signaling pathway.
Prostaglandin (PG) E2 promotes tumor growth via interaction with its G protein-coupled receptors and activation of intracellular signaling. Tuberous sclerosis 2 (tuberin) is a tumor suppressor, which negatively regulates cell growth. Its phosphorylation results in its inactivation and targeted down- regulation, thus lifting the growth inhibition effects. This study investigated the expression and localization of tuberin in neoplastic and normal endometrium and the effect of PGE2 on phosphorylation of tuberin via the Akt pathway. Quantitative RT-PCR and Western blot analysis demonstrated reduced expression of tuberin in neoplastic tissue, compared with normal endometrial tissue. Tuberin expression was localized by immunohistochemistry to the glandular epithelial compartment in neoplastic and normal endometrium. We investigated the effect of PGE2 on phosphorylation of tuberin via the Akt pathway. Treatment of neoplastic and normal endometrium with 100 nm PGE2 enhanced phosphorylated tuberin immunoreactivity in the glandular epithelium. PGE2 also phosphorylated Akt and tuberin in Ishikawa endometrial adenocarcinoma cells, leading to a reduction in expression of total tuberin protein. Cotreatment of cells with wortmannin or LY294002 inhibited the PGE2-induced phosphorylation of Akt and tuberin. These data suggest that PGE2 signaling may promote endometrial tumorigenesis by inactivation of tuberin after its phosphorylation via the Akt signaling pathway.
Sales
Kurt J
KJ
MRC Human Reproductive Sciences Unit, Center for Reproductive Biology, The University of Edinburgh Academic Center, Edinburgh EH16 4SB, United Kingdom.
Battersby
Sharon
S
Williams
Alistair R W
AR
Anderson
Richard A
RA
Jabbour
Henry N
HN
D000230:Adenocarcinoma / Q000378:metabolism* / Q000473:pathology; D000368:Aged; D015153:Blotting, Western; D045744:Cell Line, Tumor; D015232:Dinoprostone / Q000378:metabolism* / Q000494:pharmacology; D015536:Down-Regulation; D016889:Endometrial Neoplasms / Q000378:metabolism* / Q000473:pathology; D004717:Endometrium / Q000187:drug effects / Q000378:metabolism; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D012097:Repressor Proteins / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D014018:Tissue Distribution; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins
D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins; C000624653:TSC2 protein, human; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D015232:Dinoprostone