ABSTRACT
BACKGROUND: Aldo-keto reductase (AKR) 1C family member 3 (AKR1C3), one of four identified human AKR1C enzymes, catalyzes steroid, prostaglandin, and xenobiotic metabolism. In the prostate, AKR1C3 is up-regulated in localized and advanced prostate adenocarcinoma, and is associated with prostate cancer (PCa) aggressiveness. Here we propose a novel pathological function of AKR1C3 in tumor angiogenesis and its potential role in promoting PCa progression. METHODS: To recapitulate elevated AKR1C3 expression in cancerous prostate, the human PCa PC-3 cell line was stably transfected with an AKR1C3 expression construct to establish PC3-AKR1C3 transfectants. Microarray and bioinformatics analysis were performed to identify AKR1C3-mediated pathways of activation and their potential biological consequences in PC-3 cells. Western blot analysis, reverse transcription-polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay (ELISA), and an in vitro Matrigel angiogenesis assays were applied to validate the pro-angiogenic activity of PC3-AKR1C3 transfectants identified by bioinformatics analysis. RESULTS: Microarray and bioinformatics analysis suggested that overexpression of AKR1C3 in PC-3 cells modulates estrogen and androgen metabolism, activates insulin-like growth factor (IGF)-1 and Akt signaling pathways, as well as promotes tumor angiogenesis and aggressiveness. Levels of IGF-1 receptor (IGF-1R) and Akt activation as well as vascular endothelial growth factor (VEGF) expression and secretion were significantly elevated in PC3-AKR1C3 transfectants in comparison to PC3-mock transfectants. PC3-AKR1C3 transfectants also promoted endothelial cell (EC) tube formation on Matrigel as compared to the AKR1C3-negative parental PC-3 cells and PC3-mock transfectants. Pre-treatment of PC3-AKR1C3 transfectants with a selective IGF-1R kinase inhibitor (AG1024) or a non-selective phosphoinositide 3-kinases (PI3K) inhibitor (LY294002) abolished ability of the cells to promote EC tube formation. CONCLUSIONS: Bioinformatics analysis followed by functional genomics demonstrated that AKR1C3 overexpression promotes angiogenesis and aggressiveness of PC-3 cells. These results also suggest that AKR1C3-mediated tumor angiogenesis is regulated by estrogen and androgen metabolism with subsequent IGF-1R and Akt activation followed by VEGF expression in PCa cells.
Subject(s)
3-Hydroxysteroid Dehydrogenases/metabolism , Endothelial Cells/enzymology , Hydroxyprostaglandin Dehydrogenases/metabolism , Neovascularization, Pathologic/enzymology , Prostatic Neoplasms/enzymology , 3-Hydroxysteroid Dehydrogenases/genetics , Blotting, Western , Cell Line, Tumor , Cell Survival , Computational Biology , Dihydrotestosterone/metabolism , Disease Progression , Endothelial Cells/drug effects , Endothelial Cells/pathology , Enzyme-Linked Immunosorbent Assay , Estradiol/metabolism , Gene Expression Profiling/methods , Gene Expression Regulation, Neoplastic , Gene Regulatory Networks , Humans , Hydroxyprostaglandin Dehydrogenases/genetics , Insulin-Like Growth Factor I/metabolism , Male , Neovascularization, Pathologic/pathology , Oligonucleotide Array Sequence Analysis , Promoter Regions, Genetic , Prostatic Neoplasms/blood supply , Prostatic Neoplasms/genetics , Prostatic Neoplasms/pathology , Protein Kinase Inhibitors/pharmacology , Proto-Oncogene Proteins c-akt/antagonists & inhibitors , Proto-Oncogene Proteins c-akt/metabolism , Receptor, IGF Type 1/antagonists & inhibitors , Receptor, IGF Type 1/metabolism , Receptors, Calcitriol/metabolism , Retinoid X Receptors/metabolism , Reverse Transcriptase Polymerase Chain Reaction , Signal Transduction , Transfection , Tumor Suppressor Protein p53/metabolism , Up-Regulation , Vascular Endothelial Growth Factor A/metabolismABSTRACT
We examined the efficacy of combination treatments utilizing cytotoxic drugs plus inhibitors to members of the ErbB-ERK signal pathway in human prostate cancer (PCa) LNCaP C-81 cells. Under an androgen-reduced condition, 50nM gemcitabine caused about 40% growth suppression on C-81 cells. Simultaneous treatment of gemcitabine plus 10microM AG825 produced 60% suppression (p<0.03); while, 85% growth inhibition (p<0.02) was seen if AG825 was added to gemcitabine-treated cells after a 24h-interval. Our data thus showed that in androgen-reduced conditions, inhibition of ErbB-2 increases the cytotoxic efficacy of gemcitabine in PCa cells. This finding has significant implications in the choice of drugs for combination therapy as well as the order of administration for treating cancer patients.