Dickkopf‐related protein 3 promotes pathogenic stromal remodeling in benign prostatic hyperplasia and prostate cancer

Abstract

BACKGROUND Compartment-specific epithelial and stromal expression of the secreted glycoprotein Dickkopf-related protein (Dkk)-3 is altered in age-related proliferative disorders of the human prostate. This study aimed to determine the effect of Dkk-3 on prostate stromal remodeling that is stromal proliferation, fibroblast-to-myofibroblast differentiation and expression of angiogenic factors in vitro.METHODS Lentiviral-delivered overexpression and shRNA-mediated knockdown of DKK3 were applied to primary human prostatic stromal cells (PrSCs). Cellular proliferation was analyzed by BrdU incorporation ELISA. Expression of Dkk-3, apoptosis-related genes, cyclin-dependent kinase inhibitors and angiogenic factors were analyzed by qPCR, Western blot analysis or ELISA. Fibroblast-to-myofibroblast differentiation was monitored by smooth muscle cell actin and insulin-like growth factor binding protein 3 mRNA and protein levels. The relevance of Wnt/β-catenin and PI3K/AKT signaling pathways was assessed by cytoplasmic/nuclear β-catenin levels and phosphorylation of AKT.RESULTS Knockdown of DKK3 significantly attenuated PrSC proliferation as well as fibroblast-to-myofibroblast differentiation and increased the expression of the vessel stabilizing factor angiopoietin-1. DKK3 knockdown did not affect subcellular localization or levels of β-catenin but attenuated AKT phosphorylation in PrSCs. Consistently the PI3K/AKT inhibitor LY294002 mimicked the effects of DKK3 knockdown.CONCLUSIONS Dkk-3 promotes fibroblast proliferation and myofibroblast differentiation and regulates expression of angiopoietin-1 in prostatic stroma potentially via enhancing PI3K/AKT signaling. Thus, elevated Dkk-3 in the stroma of the diseased prostate presumably regulates stromal remodeling by enhancing proliferation and differentiation of stromal cells and contributing to the angiogenic switch observed in BPH and PCa. Therefore, Dkk-3 represents a potential therapeutic target for stromal remodeling in BPH and PCa. Prostate 73: 1441–1452, 2013. © 2013 The Authors. Prostate published by Willey-Blackwell. This is an open access article under the terms of the Creative Commons Attribution-Non-Commercial-NoDerivs Licence, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

DKK3 blocked translocation of β‐catenin/EMT induced by hypoxia and improved gemcitabine therapeutic effect in pancreatic cancer Bxpc‐3 cell

“…The following antibodies were used: β‐catenin, DKK3, cyclin D1, c‐Myc (Santa Cruz Biotech) 18, E‐Cadherin (Epitomics Inc.), vimentin, cleaved caspase‐3, cleaved caspase‐9, cleaved caspase‐7, cleaved PARP, E‐cadherin, vimentin, N‐Cadherin, Histone 1 (Cell Signaling Technology, Danvers, MA, USA) 19, β‐actin (Sigma‐Aldrich) 20, survivin, OCT4 and CD133 (Santa Cruz Biotech) 21, Glyceraldehyde 3‐phosphate dehydrogenase (Abcam) 22.…”

“…Whole-cell lysates were prepared using radio immunoprecipitation assay (RIPA) lysis buffer (1% Triton X-100, 1 mmol/l ethylenediaminetetraacetic acid, 100 mmol/l NaF, 1 mmol/l Na 3 VO 4 and protease inhibitor cocktail), and Western blot analyses were performed as described previously [17]. The following antibodies were used: b-catenin, DKK3, cyclin D1, c-Myc (Santa Cruz Biotech) [18], E-Cadherin (Epitomics Inc.), vimentin, cleaved caspase-3, cleaved caspase-9, cleaved caspase-7, cleaved PARP, E-cadherin, vimentin, N-Cadherin, Histone 1 (Cell Signaling Technology, Danvers, MA, USA) [19], b-actin (Sigma-Aldrich) [20], survivin, OCT4 and CD133 (Santa Cruz Biotech) [21], Glyceraldehyde 3phosphate dehydrogenase (Abcam) [22].…”

Decreased expression of Dkk1 and Dkk3 in human clear cell renal cell carcinoma

“…This indicates that Dkk3 acts as a tumor suppressor in kidney cells and that the downregulation of Dkk3 may be involved in RCC progression (16). The expression of Dkk3 has been analyzed in several types of malignancies, and downregulation of Dkk3 has been observed in glioma, breast cancer, melanoma, prostate cancer and gastrointestinal cancer (14,(35)(36)(37)(38). Further studies have revealed that the downregulation of Dkk3 in cancer was a result of epigenetic silencing by DNA methylation (17).…”

Dickkopf 3 attenuates xanthine dehydrogenase expression to prevent oxidative stress‐induced apoptosis

“…In malignant cells, DKK3 can function as either a tumor‐suppressor gene or oncogenic factor depending on cell type and context (Zenzmaier et al . ). Moreover, several reports have described increased DKK3 expression in tumor‐associated cells, such as stromal and endothelial cells, where it appears to support differentiation and tissue remodeling and is associated with a favorable prognosis (St Croix et al .…”

“…; Zenzmaier et al . ). These data suggest that DKK3 plays a distinct and complex role in cancer cell survival, differentiation and apoptosis.…”