Odero-Marah VA, Wang R, Chu G, Zayzafoon M, Xu J, Shi C, Marshall FF, Zhau HE, Chung LWReceptor activator of NF-kappaB Ligand (RANKL) expression is associated with epithelial to mesenchymal transition in human prostate cancer cells. Cell Res 18: 858-870

Molecular Urology and Therapeutics Program, Department of Urology and Winship Cancer Institute, Emory University School of Medicine, 1365B Clifton Road, NE, Atlanta, GA 30322, USA.
Cell Research (Impact Factor: 12.41). 08/2008; 18(8):858-70. DOI: 10.1038/cr.2008.84
Source: PubMed


Epithelial-mesenchymal transition (EMT) in cancer describes the phenotypic and behavioral changes of cancer cells from indolent to virulent forms with increased migratory, invasive and metastatic potential. EMT can be induced by soluble proteins like transforming growth factor beta1 (TGFbeta1) and transcription factors including Snail and Slug. We utilized the ARCaP(E)/ARCaP(M) prostate cancer progression model and LNCaP clones stably overexpressing Snail to identify novel markers associated with EMT. Compared to ARCaP(E) cells, the highly tumorigenic mesenchymal ARCaP(M) and ARCaP(M1) variant cells displayed a higher incidence of bone metastasis after intracardiac administration in SCID mice. ARCaP(M) and ARCaP(M1) expressed mesenchymal stromal markers of vimentin and N-cadherin in addition to elevated levels of Receptor Activator of NF-kappaB Ligand (RANKL). We observed that both epidermal growth factor (EGF) plus TGFbeta1 treatment and Snail overexpression induced EMT in ARCaP(E) and LNCaP cells, and EMT was associated with increased expression of RANKL protein. Finally, we determined that the RANKL protein was functionally active, promoting osteoclastogenesis in vitro. Our results indicate that RANKL is a novel marker for EMT during prostate cancer progression. RANKL may function as a link between EMT, bone turnover, and prostate cancer skeletal metastasis.

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Available from: Ruoxiang Wang, Apr 17, 2014
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    • "Androgen-independent ARCaPE and androgen-dependent LNCaP cells transfected with Snail have been previously shown to undergo EMT [21,22]. In our current study, we have shown that the levels of superoxide increased in both ARCaP and LNCaP cells transfected with Snail in vitro. "
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    ABSTRACT: Snail transcription factor can induce epithelial-mesenchymal transition (EMT), associated with decreased cell adhesion-associated molecules like E-cadherin, increased mesenchymal markers like vimentin, leading to increased motility, invasion and metastasis. Muscadine grape skin extract (MSKE) has been shown to inhibit prostate cancer cell growth and induce apoptosis without affecting normal prostate epithelial cells. We investigated novel molecular mechanisms by which Snail promotes EMT in prostate cancer cells via Reactive Oxygen Species (ROS) and whether it can be antagonized by MSKE. ARCaP and LNCaP cells overexpressing Snail were utilized to examine levels of reactive oxygen species (ROS), specifically, superoxide, in vitro using Dihydroethidium (DHE) or HydroCy3 dyes. Mitosox staining was performed to determine whether the source of ROS was mitochondrial in origin. We also investigated the effect of Muscadine grape skin extract (MSKE) on EMT marker expression by western blot analysis. Migration and cell viability using MTS proliferation assay was performed following MSKE treatments. Snail overexpression in ARCaP and LNCaP cells was associated with increased concentration of mitochondrial superoxide, in vitro. Interestingly, MSKE decreased superoxide levels in ARCaP and LNCaP cells. Additionally, MSKE and Superoxide Dismutase (SOD) reverted EMT as evidenced by decreased vimentin levels and re-induction of E-cadherin expression in ARCaP-Snail cells after 3 days, concomitant with reduced cell migration. MSKE also decreased Stat-3 activity in ARCaP-Snail cells. This study shows that superoxide species may play a role in Snail transcription factor-mediated EMT. Therefore, therapeutic targeting of Snail with various antioxidants such as MSKE may prove beneficial in abrogating EMT and ROS-mediated tumor progression in human prostate cancer.
    Full-text · Article · Mar 2014 · BMC Complementary and Alternative Medicine
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    • "Increased SNAI1 expression is considered an early event in the progress of prostate carcinogenesis but is limited to cells with invasive properties [26]. SNAI1 is also reported to enhance RANKL expression, osteoclastogenesis and bone colonization [58]. Furthermore, SNAI1 regulates CSC activity and tumorigenicity in breast and colorectal carcinoma cells [14,28]; and CRC patients with abundant SNAI1 expression exhibit high metastasis [28]. "
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    ABSTRACT: A better molecular understanding of prostate carcinogenesis is warranted to devise novel targeted preventive and therapeutic strategies against prostate cancer (PCA), a major cause of mortality among men. Here, we examined the role of two epithelial-to-mesenchymal transition (EMT) regulators, the adherens junction protein E-cadherin and its transcriptional repressor SNAI1, in regulating the aggressiveness of PCA cells. The growth rate of human prostate carcinoma PC3 cells with stable knock-down of E-cadherin (ShEC-PC3) and respective control cells (Sh-PC3) was compared in MTT and clonogenic assays in cell culture and in nude mouse xenograft model in vivo. Stemness of ShEC-PC3 and Sh-PC3 cells was analyzed in prostasphere assay. Western blotting and immunohistochemistry (IHC) were used to study protein expression changes following E-cadherin and SNAI1 knock-down. Small interfering RNA (siRNA) technique was employed to knock- down SNAI1 protein expression in ShEC-PC3 cells. ShEC-PC3 cells exerted higher proliferation rate both in cell culture and in athymic nude mice compared to Sh-PC3 cells. ShEC-PC3 cells also formed larger and a significantly higher number of prostaspheres suggesting an increase in the stem cell-like population with E-cadherin knock-down. Also, ShEC-PC3 prostaspheres disintegration, in the presence of serum and attachment, generated a bigger mass of proliferating cells as compared to Sh-PC3 prostaspheres. Immunoblotting/IHC analyses showed that E-cadherin knock-down increases the expression of regulators/biomarkers for stemness (CD44, cleaved Notch1 and Egr-1) and EMT (Vimentin, pSrc-tyr416, Integrin beta3, beta-catenin, and NF-kappaB) in cell culture and xenograft tissues. The expression of several bone metastasis related molecules namely CXCR4, uPA, RANKL and RunX2 was also increased in ShEC-PC3 cells. Importantly, we observed a remarkable increase in SNAI1 expression in cytoplasmic and nuclear fractions, prostaspheres and xenograft tissues of ShEC-PC3 cells. Furthermore, SNAI1 knock-down by specific siRNA strongly inhibited the prostasphere formation, clonogenicity and invasiveness, and decreased the level of pSrc-tyr416, total Src and CD44 in ShEC-PC3 cells. Characterization of RWPE-1, WPE1-NA22, WPE1-NB14 and DU-145 cells further confirmed that low E-cadherin is associated with higher SNAI1 expression and prostasphere formation. Together, these results suggest that E-cadherin loss promotes SNAI1 expression that controls the aggressiveness of PCA cells.
    Full-text · Article · Feb 2014 · Molecular Cancer
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    • "All animal procedures were performed according to an approved protocol from the Institutional Animal Care and Use Committee. LNRANKL, LNNeo, or LNNeo-RFP cells (1×106 cells/50 μl PBS) were tagged with the luciferase gene and inoculated intracardially or intratibially into 5- to 7-week-old male athymic nude mice (Charles River, Wilmington, MA, USA) as described previously (Odero-Marah et al. 2008). To study their interactions and recruitment, in some studies, cells were injected together or separately at different ratios or by a separate route. "
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    ABSTRACT: Prostate cancer (PCa) metastasis to bone is lethal and there is no adequate animal model to study the mechanisms underlying the metastatic process. Here we report that receptor activator of NF-κB ligand (RANKL) expressed by PCa cells consistently induced colonization or metastasis to bone in animal models. RANK-mediated signaling established a premetastatic niche through a feed forward loop, involving the induction of RANKL and c-Met, but repression of androgen receptor (AR) expression and AR signaling pathways. Site-directed mutagenesis and transcription factor deletion/interference assays identified common transcription factor complexes (TFs), c-Myc/Max and AP4, as critical regulatory nodes. RANKL-RANK signaling activated a number of master regulator TFs that control the epithelial-mesenchymal transition (EMT) (Twist1, Slug, Zeb1, Zeb2), stem cell properties (Sox2, Myc, Oct3/4 and Nanog), neuroendocrine differentiation (Sox 9, HIF-1α and FoxA2) and osteomimicry (c-Myc/Max, Sox2, Sox9, HIF1α and Runx2). Abrogating RANK or its downstream c-Myc/Max or c-Met signaling network, minimized or abolished skeletal metastasis in mice. RANKL-expressing LNCaP cells recruited and induced neighboring non-tumorigenic LNCaP cells to express RANKL, c-Met/activated c-Met, while downregulating AR expression. These initially non-tumorigenic cells, once retrieved from the tumors, acquired the potential to colonize and grow in bone. These findings identify a novel mechanism of tumor growth in bone that involves tumor cell reprogramming via RANK-RANKL signaling, as well as a form of signal amplification that mediates recruitment and stable transformation of non-metastatic cells.
    Full-text · Article · Jan 2014 · Endocrine Related Cancer
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