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CXC receptor-1 silencing inhibits androgen-independent prostate cancer.

ABSTRACT: The CXC receptor-1 (CXCR1) is a coreceptor for interleukin-8 (IL-8) and is expressed on both normal and tumor cells. The function of CXCR1 in prostate cancer was investigated by silencing its expression, using RNA interference. We established stable cell colonies of PC-3 cells, depleted of CXCR1, using lentiviral plasmids (pLK0.1puro) generating small hairpin RNA (shRNA) against CXCR1 mRNA. Stable shRNA transfectants (PLK1-PLK5) that express significantly reduced CXCR1 mRNA (>or=90% down) and protein (>or=43% down) or vector-only transfectants (PC-3V) were characterized. PLK cells showed reduced cell proliferation (down, >or=66%), due to cell cycle arrest at G(1)-S phase, decreases in Cyclin D1, CDK4, phosphorylated Rb, and extracellular signal-regulated kinase 1/2 levels compared with those in PC-3V cells. CXCR1 depletion lead to increases in spontaneous apoptosis by mitochondria-mediated intrinsic mechanism and increases in proapoptotic proteins (BAD, 40%; BAX, 12%), but decreases in antiapoptotic proteins (BCL2, down 38%; BCL(xL), 20%). PLK2 cells grew as slow-growing tumors (decrease of 54%), compared with that of PC3V tumors in athymic mice. Ex vivo analyses of PLK2 tumor tissues showed reduced expression of Cyclin D1 and vascular endothelial growth factor, and increased apoptosis activity. Other IL-8-expressing prostate cancer cell lines also exhibited similar phenotypes when CXCR1 was depleted by CXCR1 shRNA transfection. In contrast to these cells, CXCR1 depletion had little effect on IL-8 ligand-deficient LNCaP cells. RNA interference rescue using mutated CXCR1 plasmids reversed the silencing effect of PLK2, thus demonstrating the specificity of phenotypic alteration by CXCR1 shRNA. These studies establish that CXCR1 promotes IL-8-mediated tumor growth.

SUBMITTER: Shamaladevi N

PROVIDER: S-EPMC2788615 | biostudies-literature | 2009 Nov

REPOSITORIES: biostudies-literature

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CXC receptor-1 silencing inhibits androgen-independent prostate cancer.

Shamaladevi Nagarajarao N Lyn Dominic A DA Escudero Diogo O DO Lokeshwar Bal L BL

Cancer research 20091027 21

The CXC receptor-1 (CXCR1) is a coreceptor for interleukin-8 (IL-8) and is expressed on both normal and tumor cells. The function of CXCR1 in prostate cancer was investigated by silencing its expression, using RNA interference. We established stable cell colonies of PC-3 cells, depleted of CXCR1, using lentiviral plasmids (pLK0.1puro) generating small hairpin RNA (shRNA) against CXCR1 mRNA. Stable shRNA transfectants (PLK1-PLK5) that express significantly reduced CXCR1 mRNA (>or=90% down) and pr ...[more]

PMID: 19861539

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Project description:Patients with metastatic prostate cancer frequently develop bone metastases that elicit significant skeletal morbidity and increased mortality. The high tropism of prostate cancer cells for bone and their tendency to induce the osteoblastic-like phenotype are a result of a complex interplay between tumor cells and osteoblasts. Although the role of osteoblasts in supporting prostate cancer cell proliferation has been reported by previous studies, their precise contribution in tumor growth remains to be fully elucidated. Here, we tried to dissect the molecular signaling underlining the interactions between castration-resistant prostate cancer (CRPC) cells and osteoblasts using in vitro co-culture models. Transcriptomic analysis showed that osteoblast-conditioned media (OCM) induced the overexpression of genes related to cell cycle in the CRPC cell line C4-2B but, surprisingly, reduced androgen receptor (AR) transcript levels. In-depth analysis of AR expression in C4-2B cells after OCM treatment showed an AR reduction at the mRNA (p = 0.0047), protein (p = 0.0247), and functional level (p = 0.0029) and, concomitantly, an increase of C4-2B cells in S-G2-M cell cycle phases (p = 0.0185). An extensive proteomic analysis revealed in OCM the presence of some molecules that reduced AR activation, and among these, Matrix metalloproteinase-1 (MMP-1) was the only one able to block AR function (0.1 ng/ml p = 0.006; 1 ng/ml p = 0.002; 10 ng/ml p = 0.0001) and, at the same time, enhance CRPC proliferation (1 ng/ml p = 0.009; 10 ng/ml p = 0.033). Although the increase of C4-2B cell growth induced by MMP-1 did not reach the proliferation levels observed after OCM treatment, the addition of Vorapaxar, an MMP-1 receptor inhibitor (Protease-activated receptor-1, PAR-1), significantly reduced C4-2B cell cycle (0.1 μM p = 0.014; 1 μM p = 0.0087). Overall, our results provide a novel AR-independent mechanism of CRPC proliferation and suggest that MMP-1/PAR-1 could be one of the potential pathways involved in this process.

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CXC receptor-1 silencing inhibits androgen-independent prostate cancer.

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CXC receptor-1 silencing inhibits androgen-independent prostate cancer.

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