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ABSTRACT: The insulin-like growth factor (IGF) axis is associated intimately with prostate cancer (PCa) development, growth, survival and metastasis. In particular, increased levels of IGFBP-2 expression are associated with advanced PCa, bone metastasis, and the development of castrate resistant PCa. Previously, we reported that androgen treatment decreased intracellular and extracellular IGFBP-2 in the androgen sensitive (AS) PCa cell line, LNCaP. Nonetheless, the mechanism by which androgen treatment decreases expression of IGFBP-2 is not clear. Since elevated IGFBP-2 is associated with a variety of advanced cancers, including PCa, coupled with the fact that hormone ablation is the customary treatment modality for advanced PCa, a complete understanding of the influence of androgens on IGFBP-2 expression is essential. Androgen treatment initially increased steady state IGFBP-2 mRNA levels in LNCaP cells. Extended androgen treatment on LNCaP resulted in a time-dependent decrease in both steady state IGFBP-2 mRNA and protein. Polysomal mRNA analysis showed no difference in IGFBP-2 association with a given fraction; however, Q-PCR revealed less IGFBP-2 mRNA in each androgen-treated fraction. In addition, there was an overall decrease in polysome mRNA after androgen treatment. Extracellular proteolysis of IGFBP-2 was prevented in the presence of serine protease inhibitors. These data indicate that androgen acts via multiple levels to down-regulate IGFBP-2 in LNCaP PCa cells.
American Journal of Translational Research 01/2010; 2(2):200-8.
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ABSTRACT: Nine transcription factors comprise the PAX gene family that regulate organogenesis. The urogenital system of PAX2 null male mice fails to develop properly. PAX2 is overexpressed in PC3 cells. Therefore, PAX2 is implicated in both prostate organogenesis and cancer. However, the expression pattern/profile of PAX2 in the prostate is unknown.
PAX2/5/8 expression was surveyed in E16.5 male urogenital sinus (UGS) by RT-PCR. Prostate samples from 10 developmental stages in C3H male mice were used in quantitative reverse-transcript PCR (Q-PCR) and Western blotting (WB). RT-PCR and WB measured PAX2 expression in prostatic lobes or UGS layers, to identify local-regional expression patterns. Cytoplasmic versus nuclear expression was examined by WB. A castration series in adult C3H male mice and R1881 treatment in serum-free LNCaP cells examined androgen control of PAX2.
PAX2 mRNA levels are higher in early developmental stages as compared to postpubertal prostates. RT-PCR and/or WB indicated a dorsal epithelial-nuclear localization of PAX2. PAX2 mRNA and protein increase postcastration. R1881 decreases expression of PAX2 mRNA in LNCaP cells as compared to controls.
The expression profile of PAX2 indicates that it may regulate early, androgen-independent stages of murine prostate development, particularly for dorsally derived prostate glands. PAX2 expression appears to be associated with a dorsally localized epithelial cell population that is castration insensitive and retains proliferative and differentiative potential. Such a population of cells may represent a subset of stem-like cells having some characteristics in common with castrate-resistant prostate cancer cells.
The Prostate 12/2009; 70(6):654-65. · 3.48 Impact Factor
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ABSTRACT: Studies centered at the intersection of embryogenesis and carcinogenesis have identified striking parallels involving signaling pathways that modulate both developmental and neoplastic processes. In the prostate, reciprocal interactions between epithelium and stroma are known to influence neoplasia and also exert morphogenic effects via the urogenital sinus mesenchyme. In this study, we sought to determine molecular relationships between aspects of normal prostate development and prostate carcinogenesis. We first characterized the gene expression program associated with key points of murine prostate organogenesis spanning the initial in utero induction of prostate budding through maturity. We identified a highly reproducible temporal program of gene expression that partitioned according to the broad developmental stages of prostate induction, branching morphogenesis, and secretory differentiation. Comparisons of gene expression profiles of murine prostate cancers arising in the context of genetically engineered alterations in the Pten tumor suppressor and Myc oncogene identified significant associations between the profile of branching morphogenesis and both cancer models. Further, the expression of genes comprising the branching morphogenesis program, such as PRDX4, SLC43A1, and DNMT3A, was significantly altered in human neoplastic prostate epithelium. These results indicate that components of normal developmental processes are active in prostate neoplasia and provide further rationale for exploiting molecular features of organogenesis to understand cancer phenotypes.
Cancer Research 03/2009; 69(5):1739-47. · 7.86 Impact Factor
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ABSTRACT: The identification of molecular determinants involved in the promotion of metastasis and development of androgen insensitive prostate cancer (AI-PCa) is necessary to discriminate aggressive from indolent disease and to identify therapeutic targets for advanced disease. Overexpression of one particular member of the insulin like growth factor (IGF) axis, IGFBP-2, is implicated in the development of AI-PCa and other cancers. Using the LNCaP human PCa progression model, we show that the AI and metastatic prostate cancer cell line C4-2B4 expresses greater amounts of secreted IGFBP-2 than the androgen sensitive (AS), non-metastatic LNCaP progenitor cell line. Further, the ability of androgens to decrease extracellular IGFBP-2 levels is attenuated in the AI and metastatic C4-2 cell line. The ability of androgen to negatively regulate extracellular IGFBP-2 levels was blocked by Casodex in a dose-dependent manner. The mechanism underlying the androgen-induced downregulation of secreted IGFBP-2 appears to involve extracellular proteolysis, resulting in the production of IGFBP-2 fragments lacking the ability to bind IGF-I and IGF-II. As C4-2 cells have an attenuated ability to proteolyze IGFBP-2 in response to androgen and C4-2B4 cells express greater amounts of IGFBP-2, our data implies that the diminished regulation of IGFBP-2 and loss of associated proteolytic fragments play a role in the increased metastatic behavior of these cells in vivo. Furthermore, our results suggest that either increased levels of intact IGFBP-2 or decreased levels of IGFBP-2 proteolytic fragments could serve as a biomarker to monitor for progression to AI-PCa.
Journal of Cellular Physiology 11/2007; 213(1):261-8. · 3.87 Impact Factor
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ABSTRACT: Identification of the genes involved in prostate cancer (PCa) progression to a virulent and androgen-independent (AI) form is a major focus in the field. cDNA microarray was used to compare the gene expression profile of the indolent, androgen sensitive (AS) LNCaP PCa cell line to the aggressively metastatic, AI C4-2. Thirty-eight unique sequences from a 6388 cDNA array were found differentially expressed (> or =2-fold, 95% CI). The expression of 14 genes was lower in C4-2 than in LNCaP cells, while the reverse was true for 24 genes. Twelve genes were validated using Q-PCR, Western blotting and immunohistochemistry (IHC) of LNCaP and C4-2 xenograft. Q-PCR showed that 10 of 12 (83.3%) genes had similar patterns of expression to the array (LNCaP>C4-2: TMEFF2, ATP1B1, IL-8, BTG1, BChE, NKX3.1; LNCaP<C4-2: BNIP3, TM4SF1, AMACR, UCH-L1). By Western blot, 4/5 genes examined: TMEFF2, NKX3.1, AMACR, and UCH-L1, not IL-8, were consistent with RNA profiling. Protein expression levels were confirmed in human tumor xenografts using IHC. A large proportion of the markers found in this expression profile is consistent with those recently identified in human PCa tissues along with several novel genes that remain to be examined. These data further demonstrate the utility of the LNCaP human PCa progression model as a tool to investigate the phenotypic changes required for the progression to AI and metastasis.
Cancer Letters 01/2007; 244(2):274-88. · 4.24 Impact Factor
