The role of zinc transporter ZIP4 in prostate carcinoma

ObjectiveNormal prostate tissues have a unique function of accumulating high levels of zinc. This capability is lost during the early stage in the development of prostate malignancy. ZIP4 is an important zinc transporter. In this study, we explore the expression of ZIP4 in prostate carcinoma and invest the functional contributions of ZIP4 to cancer growth in vitro.MethodsZIP4 expression was detected in 14 prostate carcinoma and 20 BPH tissues by real-time RT-PCR and western blot. To invest the biological function of ZIP4 in prostate carcinoma cells, ZIP4 stable over-expression in cells was established in prostate carcinoma cell line DU145 (DU145-ZIP4) and ZIP4 short hairpin RNA(shRNA) expression in stable cells was also established in prostate carcinoma cell line 22RV1(22RV1-shRNA). The proliferation, migration, and invasion ability of the prostate carcinoma cells were detected.ResultsThe expression of ZIP4 mRNA and protein are significantly down-regulated in prostate carcinoma tissues compared with that in BPH tissues. However, we found that there was no correlation between the ZIP4 expression and the pathologic grade of prostate carcinoma. In in vitro studies, over-expression of ZIP4 not only inhibits the proliferation but also inhibits the invasive ability of prostate carcinoma cell line DU145-ZIP4. At the same time, we found silencing of ZIP4 was associated with increased cell proliferation and invasion ability in 22RV1-shRNA cell line. However, both DU145-ZIP4 and 22RV1-shRNA cells showed a significant reduction on cell migration ability compared with the control.ConclusionThe results indicate that ZIP4 expression is down-regulated in prostate carcinoma and it may serve as a promising biomarker for prostate carcinoma. ZIP4 has an inhibitory effect on prostate carcinoma cell proliferation and invasion. It suggests that ZIP4 may be a tumor suppressor gene and down-regulation of ZIP4 may be a critical early event in the development of prostate carcinoma.     

Immunohistochemistry and biochemistry in detection of androgen, progesterone, and estrogen receptors in benign and malignant human prostatic tissue.

The relative distribution of androgen (AR), progesterone (PR), and estrogen receptors (ER) was localized and estimated in human prostate tissue by immunohistochemistry in five normal tissue samples, in eight benign hyperplastic (BPH) samples, in nine primary cancers, and in seven prostate cancer metastases. Moreover, three prostatic cancer cell lines (LNCaP, DU 145, and PC 3) were analyzed. A comparison between the results obtained by radioligand binding assays and immunohistochemistry was performed for the AR and PR. Using immunohistochemistry, the AR was exclusively detected in the nuclei of both benign and malignant prostatic epithelial cells. The highest proportion of AR-positive cells was found in BPH and in prostate cancer metastases as compared with normal prostatic tissue. In a majority of the cases, the PR was only present in the nuclei of stromal cells. Benign hyperplastic prostates contained higher proportions of PR-positive cells as compared with primary carcinoma. PR was sparse in epithelial cells. ER-positive stromal cell nuclei were only detected in carcinomatous prostates. A few ER-positive epithelial cell nuclei were found in one sample each of a BPH and normal prostate. All cells from the androgen-dependent, LNCaP, cell line and a majority of the cells from the androgen-independent, DU 145, cell line were AR-positive. In contrast, the cells from the androgen-independent, PC 3, cell line were all AR-negative. All three cell lines were PR- and ER-negative. The radioligand binding technique detected the AR in extracts from both the cytosol and the nucleus. Again BPH contained higher amounts of AR as compared with normal prostatic tissue. The LNCaP cells contained high amounts of cytosolic AR while cells from the DU 145 and PC 3 cell lines lacked detectable AR as estimated by biochemical techniques. There seemed to be a discrepancy between biochemically measured and immunohistochemically estimated receptor content.     

花粉提取物对前列腺增生细胞作用的研究

将前列腺增生来源的上皮细胞和成纤维细胞在体外进行培养，并观察花粉提陂物对细胞的体外作用。结果证明花粉提取物可明显地抑制前列腺增生的上皮细胞或成纤维细胞的增殖，且上皮细胞的反应更为敏感。本结果对进一步研究花粉类物质对前列腺细胞的作用机理提供一定的帮助。     

Characterization of a stromal cell model of the human benign and malignant prostate from explant culture

PURPOSE: There is a lack of suitable in vitro models for the human prostate. To study stromal-epithelial interactions, we established stromal cells in cultures from benign and malignant prostate tissue that resemble more closely the in vivo conditions of the human prostate. MATERIALS AND METHODS: Stromal cells were obtained from explant primary culture, established in DU145 cell conditioned medium and maintained in RPMI-fetal bovine serum (FBS) supplemented with insulin, transferrin and selenium (ITS). Proliferation studies to compare different media were performed using a 3[H]thymidine assay. Stromal cells were characterized by immunocytochemistry using epithelial and mesenchymal markers. Morphology was evaluated by electron microscopy, light and phase-contrast microscopy. Androgen receptor (AR) mRNA expression was measured by polymerase-chain-reaction (PCR). The response to different concentrations of dihydrotestosterone (DHT) and the antihormones flutamide and hydroxyflutamide was tested by 3[H] thymidine assay. RESULTS: Microscopic evaluation revealed typical stromal morphology with elongated cell shapes, cilia, collagen and microfilaments. Immunocytochemical characterization revealed typical fibroblastic and smooth muscle differentiation. ITS supplemented in RPMI-FBS showed the best growth stimulation compared with other serum-free media (p <0.05) and became our basal medium. The presence of DU145 cell conditioned medium in this basal medium showed a significant increase in cell proliferation in stromal cells. Stromal cells maintained AR mRNA expression and significant DHT dose dependent growth stimulation in up to 10 passages. Both the antiandrogens flutamide and hydroxyflutamide counteracted the DHT effect (p <0.05). CONCLUSIONS: This stromal cell model maintains many cellular and functional properties of the human prostate, which may enable us to study growth factor modulation, drug and hormone metabolism in stromal-epithelial interaction with emphasis on the pathogenesis of BPH and prostate cancer.     

Differential cytokeratin expression in normal, hyperplastic and malignant epithelial cells from human prostate.

Studies were undertaken to define the expression of cytokeratins in normal, hyperplastic and malignant epithelial cells from human prostate. Cytokeratin (CK) polypeptides, separated by two-dimensional electrophoresis, were identified by immunoblotting with CK-specific monoclonal antibodies. CK polypeptides 5, 7, 8, 15, 18 and 19 were identified in fresh normal and hyperplastic prostate. Expression of CK 15 has not been previously reported in human prostate. Analysis of central and peripheral zone tissues from human prostate did not reveal qualitative differences in CK expression between these areas. Epithelial cells harvested from fresh BPH tissue by percoll gradient centrifugation and propagated in vitro using selective culture techniques showed alterations in CK expression compared to intact human prostate. Specifically, CKs 6, 14, 16 and 17 were noted in cultured BPH epithelial cells but not fresh normal prostate or BPH tissue. Immunoblot analysis of the established prostate cancer cell lines PC3, DU145 and LNCAP showed expression of CKs 8 and 18 but not CKs 5, 7 and 15 which were observed in benign prostate. These studies further characterize CK expression in benign and malignant human prostate and provide insights which may be useful in differentiating normal, hyperplastic and malignant epithelial cells in the human prostate gland.     

Down-regulation of macrophage inhibitory cytokine-1/prostate derived factor in benign prostatic hyperplasia

BACKGROUND: Macrophage inhibitory cytokine-1 (MIC-1) is a member of transforming growth factor-beta/bone morphogenetic protein (BMP) superfamily. Despite its potential role in prostatic regulation, little is known about its biological activity. METHODS: Expression profiling using 42K Affymetrix HuGeneFL array was conducted to compare symptomatic benign prostatatic hyperplasia (BPH), histological BPH without symptoms, and normal prostate samples from donors. MIC-1 gene expression was analyzed by RT-PCR in pure culture of prostate epithelial and stromal cells, and prostate cancer cells, LNCaP, PC-3, DU-145. Influence of androgens on MIC-1 expression in LNCaP cells was analyzed by Northern blot. Enhancement of promoter activity of MIC-1 by androgens was examined using reporter assays. RESULTS: In contrast to normal prostates, MIC-1 gene was down-regulated in BPH samples with symptoms and histological BPH obtained from cystoprostatectomy specimens (P < 0.005 and P < 0.01, respectively). Expression level of MIC-1 in androgen-sensitive LNCaP cells was high and enhanced by androgens, whereas in the androgen-insensitive PC-3 and DU-145 cells the expression level was low. An 11 kb promoter region of MIC-1 gene was identified to be 6- to 12-fold activated by androgens. CONCLUSIONS: Down-regulation of MIC-1 may play a role in the development of BPH. MIC-1 is positively regulated by androgens, but other regulatory factors remain unclear.     

组织激肽释放酶基因7在前列腺癌组织中的表达

目的 探讨组织激肽释放酶基因7(KLK7)在不同前列腺组织中的表达情况.方法运用逆转录聚合酶链反应法检测正常前列腺(5例)、良性前列腺增生(BPH)及BPH细胞株(BPH1,13例)、前列腺癌及前列腺癌细胞株(8例)的上皮细胞中KLK7mRNA表达水平;蛋白质印迹法检测不同前列腺组织上皮细胞中KLK7蛋白表达水平;免疫组化分析正常前列腺(20例)、BPH(50例)、前列腺癌(103例)组织中KLK表达水平.根据染色强度分为4个等级(-,+,++,+++)进行半定量分析,染色强度++及+++者判定为阳性.结果 正常组、BPH组和前列腺癌组KLK7 mRNA表达相对值分别为0.59、0.52、0.02,组间比较差异有统计学意义(F=13.03,P＜0.01),前列腺癌上皮中KLK7 mRNA表达下调(P＜0.01),正常前列腺和BPH上皮中KLK7 mRNA表达差异无统计学意义(P＞0.05).KLK7蛋白在正常前列腺、增生前列腺、DU145、LNCaP、PC3、22RV1、BPH细胞株中表达水平相对值分别为0.22、0.40、0.01、0.05、0、0.03、0.14.免疫组化染色结果 显示正常前列腺组织、BPH组织、前列腺癌中KLK7蛋白表达阳性率分别为65.0%(13/20)、76.0%(38/50)、17.5%(18/103),前列腺癌组与前2组比较差异均有统计学意义(P＜0.01),前2组间比较差异无统计学意义(P＞0.05).结论 KLK7在前列腺癌组织中表达下调,提示KLK7在前列癌的发生和进展中可能起一定作用.     

Antitumor activity and downregulation of pro-angiogenic molecules in human prostate cancer cells by a novel thiazolidione compound

BACKGROUND: Current treatments for prostate cancer are effective in many patients with locally advanced disease, but many of these patients eventually have recurrence. It is therefore important to develop alternative therapeutic agents with improved efficacy and tolerability. We recently identified a synthetic thiazolidin compound, 5-(2,4-dihydroxybenzylidene)-2-(phenylimino)-1,3-thiazolidione (DBPT), that induces apoptosis in human colon cancer cells, independent of p53 and P-glycoprotein status. Here, we investigated the antitumor properties and mechanisms of action of this compound in human prostate cancer cell lines. METHODS: The effect of DBPT on cell-cycle progression and apoptosis in LNCaP and DU145 cells was examined by flow cytometry and Western blotting. The effect of DBPT on pro-angiogenic molecules was analyzed by Western blotting and by an enzyme-linked immunosorbent assay. RESULTS: DBPT inhibited the growth of LNCaP and DU145 cells with 50% inhibitory concentrations ranging from 1.6 to 5.9 microM. Treating LNCaP and DU145 cells with DBPT led to a time-dependent cell-cycle arrest in the G(2)/M phase and increased levels of G(2)/M checkpoint proteins, such as cyclin B1, cdc25C, phosphorylated histone H(3), and MPM-2. DBPT induced the phosphorylation of Bcl-xL and Bim, and induced apoptosis, as evidenced by cleavage of caspase and poly (ADP-ribose) polymerase. DBPT also effectively induced apoptosis in Bcl-2-overexpressing DU145 cells. Furthermore, DBPT decreased hypoxia-inducible factor 1 alpha and vascular endothelial growth factor expression in LNCaP cells under both normoxia and hypoxia. CONCLUSIONS: DBPT can suppress proliferation, induce apoptosis, and down regulate pro-angiogenic molecules in prostate cancer cells, and might be useful in treating prostate cancer.     

Secretion of epidermal growth factor and related polypeptides by the DU 145 human prostate cancer cell line

Epidermal growth factor (EGF)-like proteins may be important in regulating the growth of human prostate cancer cells and in the development of hormone independence. In the present study, we demonstrated that the DU 145 human prostate cancer cell line secretes EGF-like polypeptides into serum-free culture medium. The production of both authentic EGF and transforming growth factor-alpha was demonstrated by specific radioimmunoassays. In addition to 6-7k monomers, immunoreactive higher molecular weight species were isolated by gel chromatography. The DU 145 cells also specifically bound human EGF, with both high- (Kd 1.8 x 10(-10) M) and low- (Kd 1.1 x 10(-9) M) affinity binding sites. Exogenous EGF stimulated 3H-thymidine incorporation when cells were plated at low density in serum-free culture medium, while at higher cell density neither cell division nor 3H-thymidine incorporation was significantly altered. We postulate that DU 145 cells may be autologously stimulated by endogenously produced EGF and related polypeptides, which, under normal culture conditions, precludes any further effect of exogenous EGF.     

Epidermal growth factor modulates the expression of vascular endothelial growth factor in the human prostate

The growth and dissemination of tumors in the body has been associated with angiogenesis. Vascular endothelial growth factor (VEGF) is an angiogenic factor that stimulates endothelial cell growth and enhances vascular permeability. VEGF exerts its action by binding to specific cell surface receptors. Three receptors, VEGFR-1 (flt-1), VEGFR-2 (flk-1), and VEGFR-3 (flt-4) have been identified. Very little information on the coordinated expression of VEGF and its receptors in normal prostate, benign prostatic hyperplasia (BPH), and prostate carcinoma is available. Therefore, we examined the immunohistochemical localization of VEGF and its receptors in tissues derived from normal human prostate, BPH, and prostatic carcinoma. Immunostaining for VEGF was absent in the normal prostate. Epithelium lining the glands of prostate derived from patients with BPH exhibited strong immunostaining. The intensity of staining was relatively less in prostate carcinoma. It is interesting that VEGFR-1 and VEGFR-3 were strongly expressed in both stromal and epithelial tissues in normal prostate, BPH, and carcinoma. In comparison, VEGFR-2 was not localized to normal prostate and its expression in the stroma of BPH and epithelium of carcinoma was very weak. Because progression of prostate cancer is accompanied by altered expression of epidermal growth factor (EGF) and its receptor (EGFR) in malignant cells, we investigated the effect of EGF on VEGF gene expression by Northern blot analysis in 2 human prostate cancer cell lines that express EGFR. EGF greatly enhanced the expression of VEGF messenger RNA in DU145 and PC3 cell lines in a dose-dependent manner. The EGF induction of VEGF gene expression suggests a mechanism by which angiogenesis could be accelerated in BPH and prostate carcinoma.     

胞嘧啶脱胺酶/5-氧胞嘧啶基因系统对前列腺癌细胞系生长的抑制作用

目的　探讨胞嘧啶脱胺酶 (cytosinedeaminase,CD) / 5 氟胞嘧啶基因 (5 FC)基因系统对体外前列腺癌细胞生长的作用。　方法　经基因重组并纯化的腺病毒AdCMVCD分别感染体外前列腺癌细胞DU 14 5、RM 1,观察CD/ 5 FC系统对细胞的生长抑制作用和旁观者效应。　结果　CD/5 FC系统能明显抑制体外前列腺癌细胞系DU14 5、RM 1的生长 ,经 10 0m .o .i(multiplicityofinfec tion)AdCMVCD感染并加入 15 .5mmol/L 5 FC后 4、6d ,细胞抑制率高于 97% ;同时此系统具有很强的旁观者效应 ,当受染细胞混合比例为 10 %时 ,即有 >75 %的细胞被杀死。　结论　CD/ 5 FC系统是一种有效的基因治疗方法 ,旁观者效应为此系统在实体肿瘤中的应用提供了可行性。     

Neutral endopeptidase inhibits prostate cancer tumorigenesis by reducing FGF-2-mediated angiogenesis

Neutral endopeptidase (NEP) is a cell surface peptidase that catalytically inactivates a variety of physiologically active peptides including basic fibroblast growth factor (FGF-2). We investigated the effect of using lentivirus to overexpress NEP in NEP-deficient DU145 prostate cancer cells. Third-generation lentiviral vectors encoding wild-type NEP (L-NEP), catalytically inactive mutant NEP (L-NEPmu), and green fluorescent protein (L-GFP) were stably introduced into DU145 cells. FGF-2 levels in cell culture supernatants decreased by 80% in L-NEP-infected DU145 cells compared to cells infected with L-NEPmu or L-GFP (P<0.05) while levels of other angiogenic factors were not altered. In vitro tubulogenesis of human vascular endothelial cells induced by conditioned media from DU145 cells infected with L-NEP was significantly reduced compared with that from DU145 cells infected with L-GFP (P<0.05). Tumor xenografts from L-NEP-infected DU145 cells were significantly smaller compared to control cell xenografts and vascularity within these tumors was decreased (P<0.05). Our data suggest that stable expression of NEP in DU145 cells inhibits prostate cancer tumorigenicity by inhibiting angiogenesis, with a probable mechanism being proteolytic inactivation of FGF-2.     

Prostate stromal cell-derived hepatocyte growth factor induces invasion of prostate cancer cell line DU145 through tumor-stromal interaction.

BACKGROUND: In prostate cancer, several growth factors derived from stromal cells regulate tumor cell growth. Hepatocyte growth factor (HGF) possesses biological activities that promote cancer proliferation and invasion through tumor-stromal interaction. We examined how prostate stromal cell-derived HGF affects invasion of prostate cancer cells through this interaction. METHODS: The effects of HGF, various growth factors (transforming growth factor (TGF)-alpha, TGF-beta1, basic fibroblast growth factor, keratinocyte growth factor, and platelet-derived growth factor), and conditioned medium (CM) from prostate stromal cells (PrSC) on prostate cancer cells (LNCaP, PC-3, and DU145) were determined by collagen gel invasion assay. DU145 cells and PrSC were cocultured for Matrigel invasion chamber assay. Induction activity of CM from cancer cells to stimulate HGF production by PrSC was studied by the ELISA method and Western blotting. RESULTS: LNCaP and PC-3 cells did not respond to any of the factors examined. Invasion of DU145 cells into the collagen gel matrix was induced by HGF and TGF-beta1, but not by any of the other factors tested. When DU145 cells were cultured in CM from PrSC or cocultured with PrSC, the cells acquired invasive potential, and this invasion was inhibited by an antibody against HGF, but not against TGF-beta1. Native-type HGF production in PrSC was enhanced by some unknown inducer(s) produced by cancer cells. CONCLUSIONS: PrSC-derived HGF enhanced invasive activity of the prostate cancer cell line DU145 through tumor-stromal interaction, wherein DU145 cells secreted some HGF-inducer(s) for PrSC.     

Protease-activated receptor-1 upregulates fibroblast growth factor 7 in stroma of benign prostatic hyperplasia

BACKGROUND: Benign prostatic hyperplasia (BPH) is characterized by abnormal epithelial and stromal proliferation causing urinary obstruction. Prostate growth is regulated by a variety of growth factors secreted from the stroma, including fibroblast growth factor 7 (FGF-7), a potent epithelial-specific growth factor which is increased in hyperplastic prostate. However, the mediator(s) of FGF-7 over-expression is unclear. Protease-activated receptor-1 (PAR-1) is a G-protein coupled receptor known to induce multiple biological processes, but its effect on BPH pathogenesis is mostly unknown. The aim of this study was to investigate the role of PAR-1 as a mediator of BPH development. METHODS: PAR-1 expression was investigated in BPH and normal prostate tissues by immunohistochemistry. Prostate stromal cells were isolated from BPH specimens, cultured and immunohistochemically characterized. Cultured stromal cells were stimulated with PAR-1 agonists, and extracellular-signal regulated kinase (ERK1/2) activation and cell proliferation were examined. PAR-1 mediated FGF-7 production by cultured stromal cells was assessed by RT-PCR and immunoassays, and verified by small interfering RNA (siRNA). RESULTS: PAR-1 expression was increased in BPH stroma. In stromal cells isolated from BPH tissues, PAR-1 agonists activated ERK1/2 in a time- and concentration-dependent manner and with resultant enhanced cell proliferation. Pertussis toxin-sensitive G protein/(betagamma-subunits)-phosphatidylinositol 3-kinase and protein kinase C pathways were involved in ERK1/2 phosphorylation. PAR-1 activation strikingly induced FGF-7 production from cultured stromal cells mediated predominantly via ERK1/2 signaling pathway, and PAR-1 siRNA decreased the elicited FGF-7 upregulation. CONCLUSIONS: The expression and function of PAR-1 in BPH stroma indicate PAR-1 may play important roles in BPH pathogenesis.     

Combination of genistein with ionizing radiation on androgen-independent prostate cancer cells

Aim: To study the effect of the combined use of genistein and ionizing radiation (IR) on prostate DUI45 cancer cells. Methods: DU145, an androgen-independent human prostate cancer cell line, was used in the experiment.Clonogenic assay was used to compare the survival of DU145 cells after treatments with genistein alone and in combination with graded IR. Apoptosis was assayed by DNA ladder and TUNEL stain. Cell cycle alterations were observed by flow cytometry and related protein expressions by immunoblotting. Results: Clonogenic assay demonstrated that genistein, even at low to medium concentrations, enhanced the radiosensitivity of DU 145 cells. Twenty four hours after treatment with IR and/or genistein, apoptosis was mainly seen with genistein at high concentrations and was minimally related to IR. At 72 h, apoptosis also occurred in treatment with lower concentration of genistein,especially when combined with IR. While both IR and genistein led to G2/M cell cycle arrest, combination of them further increased the DUI45 cells at G2/M phase. This G2/M arrest was largely maintained at 72 h, accompanied by increasing apoptosis and hyperdiploid cell population. Cell-cycle related protein analysis disclosed biphasic changes in cyclin B 1 and less dramatically cdc-2, but stably elevated p21^cip1 levels with increasing genistein concentrations.Conclusion: Genistein enhanced the radiosensitivity of DUI45 prostate cancer cells. The mechanisms might be involved in the increased apoptosis, prolonged cell cycle arrest and impaired damage repair. (Asian J Androl 2004 Dec; 6: 285-290)     

鱼藤素诱导人前列腺癌细胞凋亡及其机制研究

目的 观察鱼藤素对于激素抵抗型前列腺癌(HRPC)细胞PC3和DU145增殖、细胞周期和凋亡的影响并探讨其机制.方法 设阴性对照组(有细胞但不加药),空白对照组(无细胞仅有培养液),阳性对照组(渥曼青霉素100 nmoL/L),及鱼藤素分别10、100、1 ìmol/L共6组.CCK-8法进行细胞毒性实验,检测细胞生长抑制率.流式细胞术检测细胞周期和凋亡,Westem-blot检测Akt、MAPK及其磷酸化蛋白表达,探讨药物作用机制.结果 10 nmol/L～1 ìmol/L鱼藤素对PC3细胞均有生长抑制作用,呈现明显的时间、浓度依赖性,对DU145细胞则无此作用.鱼藤素使PC3细胞出现G2/M期阻滞现象并引起浓度依赖性的凋亡,而未改变DU145细胞的周期分布也不能诱导其凋亡.鱼藤素能够阻断P13K/AKT通路而对MAPK通路无影响.结论 鱼藤素通过阻断PI3K/AKT通路实现抑制PC3细胞增殖、诱导凋亡的作用.两株细胞间实验结果 的差异是因为其PI3K/AKT通路活化状态的差异造成的.     

siRNA靶向沉默B7-H4基因对人前列腺癌DU145细胞增值和凋亡的影响

目的研究siRNA沉默B7-H4基因对人前列腺癌DUl45细胞增殖和凋亡的影响。方法以脂质体Lipofeclami-ne“2000（Lipo）为载体转染siRNA-B7-H4至DUl45细胞,应用RT-PCR和WesternBlot检测B7-H4表达水平,CCK-8法检测细胞增殖的变化,Annexinv／PI双染流式细胞术检测细胞凋亡情况。结果与空白组和阴性对照组（NC）相比,转染B7-H4-siRNA的细胞B7-H4mRNA和蛋白表达明显减少（P〈0．05）,DUl45转染B7-H4siRNA后,增殖能力减弱,凋亡显著。结论通过B7-H4-siRNA抑制DUl45细胞B7-H4的表达,可以抑制细胞增殖,促进其凋亡,表明B7-4在前列腺癌的发生发展中发挥重要作用。