Suppression of hepatocyte growth factor activator inhibitor-1 leads to a more aggressive phenotype of prostate cancer cells in vitro

The hepatocyte growth factor (HGF) pathway has been well documented as playing a vital role in the progression and development of many different types of human cancers; as such this pathway is usually tightly regulated. In cancer cells, the regulation of this pathway has been shown to be disrupted, allowing an increase in activation of pro-HGF to active HGF. There are a number of molecules capable of activating pro-HGF, such as matriptase-1, a type II transmembrane serine protease, or hepatocyte growth factor activator, and in turn, these are also subject to regulation. In the current study we examined the importance of hepatocyte growth factor activator inhibitor-1 (HAI-1) which is known to inhibit a number of HGF-activating molecules. We reduced the expression of this molecule in both PC-3 and DU-145 cell lines using hammerhead ribozyme technology, and we examined various important characteristics associated with cancer progression and development in vitro. Prostate cancer cells, after loss of HAI-1, had a significantly increased in vitro invasiveness together with an increase in cellular motility. Notably, loss of HAI-1 resulted in a slower rate of cell growth over a prolonged period (5 days). This in vitro evidence collectively suggests that the suppression of HAI-1 expression gives rise to a more aggressive cancer cell phenotype. This implies that therapies inducing the overexpression of HAI-1 or delivering an exogenous source of HAI-1 protein may hold potential as a treatment to slow the progression of prostate cancer.     

Reactive oxygen intermediates induce monocyte chemotactic protein-1 in vascular endothelium after brief ischemia

Matriptase and its cognate, Kunitz-type serine protease inhibitor, HAI-1, comprise a newly characterized extracellular matrix-degrading protease system that may function as an epithelial membrane activator for other proteases and latent growth factors. Both enzyme and inhibitor have been detected in breast cancer cells, immortalized mammary epithelial cells, and human milk, but not in cultured fibroblasts nor in fibrosarcoma cells. To test the hypothesis that this system is expressed by normal breast epithelium, invasive breast cancers, and other cancers of an epithelial origin (carcinomas) but not in cancers of a mesenchymal origin, we have expanded our expression analysis of matriptase and HAI-1 in vitro and in vivo. Matriptase and HAI-1 were detected at the protein and mRNA levels both in hormone-dependent and hormone-independent cultured breast cancer cells, and this expression correlated with the expression of the epithelial markers E-cadherin or ZO-1. However, none of the breast cancer cell lines tested that express the mesenchymal marker vimentin express matriptase or HAI-1, consistent with an epithelial-selective expression of this system. Expression of matriptase, as determined by Western blot analysis, was observed in primary human breast, gynecological, and colon carcinomas, but not in stromal-derived ovarian tumors and human sarcomas of various origins and histological grades. The epithelial-selective expression of matriptase and HAI-1 was further confirmed in human breast cancers by immunohistochemistry and in situ hybridization, where the expression of the protease and the inhibitor were found in the carcinoma cells and in surrounding normal breast epithelia. The expression of the matriptase/HAI-1 system by malignant epithelial cells in vivo suggests a possible role for this protease in multiple aspects of the pathophysiology of epithelial malignancy, including invasion and metastasis.     

Normal and malignant prostate epithelial cells differ in their response to hepatocyte growth factor/scatter factor

Hepatocyte growth factor/scatter factor (HGF/SF) promotes the proliferation, differentiation, motility, and invasion of epithelial cells by binding to its cell surface receptor, the Met tyrosine kinase. In the prostate, Met is expressed predominantly by prostate epithelial cells (PrEC), whereas HGF/SF is synthesized by prostate stromal cells (PrSC). Met is also expressed in localized and metastatic prostate cancers. Our results show that PrECs in in vitro culture maintain expression of Met at a level comparable to DU145 cancer cell expression. HGF/SF secreted by PrSC stimulates tyrosine phosphorylation of the Met receptor. In normal PrEC, HGF/SF causes growth inhibition, sustained phosphorylation of mitogen-activated protein kinase, and increased CK18 expression consistent with cell differentiation. In contrast, HGF/SF significantly stimulates the proliferation of DU145 prostate cancer cells. HGF/SF in the conditioned medium of PrSC specifically induces migration of both normal and malignant prostate epithelial cells through MatriGel-coated Transwell filters. HGF/SF depletion reduces cell migration by approximately 50%. The response of PrEC is specific for HGF/SF since the other growth factors tested do not significantly affect growth or migration of PrECs. These results support the in vivo importance of the prostate stroma and specifically of HGF/SF as a unique stromal derived factor in the development and progression of prostate cancer.     

婆罗双树样基因4在人前列腺癌细胞和组织中的表达及其与临床预后之间的关系

 目的：评估婆罗双树样基因4（SALL4）在人前列腺癌细胞系和前列腺癌组织中的表达情况,并明确其表达水平和临床病理学参数间的关系。方法：用免疫荧光技术、RT-PCR和Western blotting检测SALL4在LNCaP、DU145、PC-3细胞系和RWPE-1正常前列腺上皮细胞系中的表达。同时用免疫组化方法检测SALL4在前列腺增生及前列腺癌组织中的表达,并探讨其与Gleason评分等临床病理参数的关系。结果： SALL4蛋白在细胞中主要表达于胞浆,在3种前列腺癌细胞株中SALL4蛋白表达水平要明显高于正常前列腺上皮细胞RWPE-1（P＜005）,而SALL4 mRNA表达水平在4种细胞系中无明显差异（P＞0.05）。免疫组化结果显示SALL4在前列腺癌组织中的表达水平明显高于增生和正常前列腺组织（P＜0.01）。SALL4蛋白表达水平与Gleason评分、前列腺癌临床分期、预后及组织前列腺特异抗原（PSA）表达密切相关,而与患者年龄、治疗前血清总PSA水平、前列腺体积及组织雄激素受体表达无明显相关性。结论：SALL4蛋白在前列腺癌中高表达,提示其在前列腺癌的发生、发展过程中可能起重要作用,有可能成为诊断前列腺癌新的肿瘤标志物及评估其恶性程度、进展和预后的参考指标。     

肝细胞生长因子激活因子抑制因子-1的表达与功能

肝细胞生长因子激活因子抑制因子-1(hepatocyte growth factor activator inhibitor type1,HAI-1)是一种Kunitz型丝氨酸蛋白酶抑制因子,定位于细胞的基底侧,具有膜型和分泌型两种形式,能有效抑制肝细胞生长因子激活因子HGFA和丝氨酸蛋白酶Matriptase的活性,参与HGF/c-Met信号传导途径调节。HAI-1在包括妊娠、再生及肿瘤等各种正常生理及病理状态下均有不同水平的表达,其表达水平的变化以及其与靶蛋白酶表达比例的变化直接影响到靶蛋白酶的活性,从而在调控个体发育、血管生成、组织损伤修复以及抑制肿瘤的侵袭性生长等生理和病理过程中发挥重要作用。     

ENDOD1在前列腺癌组织及细胞中的表达及意义

目的:观察比较核酸内切酶结构域内含蛋白1(endonuclease domain containing1,ENDOD1)在良性前列腺增生和前列腺癌组织中的表达差异;筛选存在ENDOD1特异性低表达的前列腺癌细胞系,继而通过调控该细胞ENDOD1蛋白表达,研究其在前列腺癌细胞中的生物学功能,初步探索ENDOD1基因与前列腺癌发生、进展的联系。方法:利用免疫组化SP法检测20例良性前列腺增生和21例前列腺癌术后标本组织中ENDOD1表达情况;利用RT-qPCR和Western blot方法观察ENDOD1的mRNA和蛋白在前列腺正常上皮细胞和不同类型前列腺癌细胞中的表达差异,筛选出特异性低表达细胞系;构建pCMV-N-Flag-ENDOD1重组质粒,转染前列腺癌细胞株,过表达ENDOD1蛋白,通过MTT法测定调控前后前列腺癌细胞活力的变化,流式细胞术检测细胞周期和凋亡,Transwell实验评价肿瘤细胞迁移和侵袭能力的改变。结果:免疫组化评分的方差分析结果显示ENDOD1表达与前列腺癌Gleason评分呈负性关联;RT-qPCR和Western blot实验结果表明ENDOD1在雄激素非依赖性前列腺癌细胞系PC3和DU145中存在着特异性低表达(P0.05)。同时,MTT实验显示,在DU145细胞中,过表达ENDOD1肿瘤细胞活力显著下降(P0.05);而流式细胞术检测结果表明过表达ENDOD1能够使DU145细胞周期停滞在G_0/G_1期,但细胞凋亡率无明显差异。此外,在Transwell实验中,过表达ENDOD1的DU145细胞迁移和侵袭能力明显下降(P0.05)。结论:ENDOD1在Gleason评分越高的前列腺癌中表达越低,同时在雄激素非依赖性前列腺癌细胞系存在着特异性低表达;而过表达ENDOD1能明显抑制雄激素非依赖性前列腺癌细胞的生长、迁移和侵袭能力。     

Intermediate cells in human prostate epithelium are enriched in proliferative inflammatory atrophy

Within the human prostate epithelium four cell populations can be discriminated based on their expression of keratins (K). Basal cells express high levels of K5 and K14, as well as p63, whereas they have very low levels of androgen receptor, prostate-specific antigen (PSA), K8, and K18. Luminal secretory cells lack p63, K5, and K14 but express high levels of K8, K18, androgen receptor, and PSA. Additionally, cells have been identified with a keratin phenotype intermediate between basal and luminal cells that co-express high levels of K5 and K18 (K5/18) as well as hepatocyte growth factor receptor c-MET. Although intermediate cells have been proposed as precursor cells of prostate cancer, their biology is ill defined. Epithelial cells in proliferative inflammatory atrophy (PIA) appear to be cycling rapidly as indicated by expression of Ki-67, and morphological transitions have been identified between PIA and high-grade prostate intraepithelial neoplasia. Many of the atrophic epithelial luminal cells in PIA are candidates for intermediate cells based in part on weak expression of PSA and androgen receptor, high levels of K8/18, and lack of p63. The objective of this study was to further clarify the phenotype of the proposed intermediate cells in PIA and to quantitatively determine the level in which these intermediate cells preferentially occur in PIA lesions. Intermediate cells were immunohistochemically demonstrated using antibodies to K5, K14, K18, and c-MET. Using radical prostatectomy specimens (n = 15) the area fraction of intermediate cells in normally differentiated prostate epithelium and PIA were quantified by a grid point counting method. Atrophic luminal cells of PIA lesions expressed K5 in 39.2 +/- 7.4% of cells compared to 2.4 +/- 2.3% in normal epithelium (P < 0.00001). By contrast, K14 was only expressed in 3.0 +/- 3.2% of the luminal cells. Previous studies have shown that virtually 100% of these atrophic luminal cells are strongly positive for K8/18. c-MET was present in 44.1 +/- 14.1% of luminal cells in PIA but only in 2.1 +/- 2.8% of luminal cells in normal epithelium (P < 0.00001). To unambiguously determine whether intermediate luminal cells in PIA show increased proliferative activity and decreased p27(kip1) expression, double-staining immunofluorescence of Ki-67 and K5, as well as p27(Kip1) and K5 was performed. Luminal cells in PIA often co-expressed K5 and Ki-67. Although p27(Kip1) was strongly expressed in K5-negative differentiated cells in normal epithelium, p27(Kip1) staining was absent in many of the K5-positive cells in the luminal compartment of PIA. We conclude that cells phenotypically intermediate between basal and secretory cells are enriched in PIA lesions. The finding of a large number of highly proliferating intermediate cells in PIA provides further support that these cells may serve as preferred target cells in prostate carcinogenesis.     

The androgen-regulated type II serine protease TMPRSS2 is differentially expressed and mislocalized in prostate adenocarcinoma

Transmembrane serine protease 2 (TMPRSS2) is an androgen-regulated member of the type two transmembrane protease (TTSP) family. Two other members of the TTSP family, matriptase and hepsin, are over-expressed in prostate adenocarcinoma and mechanistically influence cancer cell invasion and metastasis. This study was performed to determine TMPRSS2 protein expression in primary and metastatic prostate cancers. We developed a monoclonal antibody capable of the sensitive and specific detection of TMPRSS2 protein. TMPRSS2 regulation by androgen and presence in seminal fluid was measured. TMPRSS2 localization and expression was evaluated in 415 cases of primary prostate cancer and 144 prostate cancer metastases by immunohistochemistry. We determined that TMPRSS2 protein expression is regulated by androgens and that TMPRSS2 is a component of the normal seminal fluid proteome. TMPRSS2 protein is abundantly expressed in the prostate, with low levels in the epithelia of the colon, stomach, epididymis and breast. Pancreatic acini, hepatic bile ducts, testicular Leydig cells and the kidney also express TMPRSS2. In the prostate, TMPRSS2 protein is specifically localized to the secretory epithelium, with enhanced expression in the plasma membrane orientated towards the ductal lumen. TMPRSS2 expression was significantly higher in both neoplastic prostate and in the epithelium of prostatic hyperplasia compared to normal epithelium (p < 0.01). TMPRSS2 expression was further elevated in higher Gleason grade cancers (patterns 4 and 5) compared to pattern 3 (p = 0.04). Furthermore, in most high-grade cancers, TMPRSS2 was mislocalized, being expressed in the cytoplasm as well as in the cell membrane. Prostate cancer metastases also generally expressed high levels of TMPRSS2. In summary, the TMPRSS2 protease is expressed highly in primary and metastatic prostate cancers and is associated with tumour cell differentiation. Based on studies with the related proteins matriptase and hepsin, TMPRSS2 should be investigated for causal roles in prostate carcinogenesis.     

Increased stability of macrophage migration inhibitory factor (MIF) in DU-145 prostate cancer cells.

Macrophage migration inhibitory factor (MIF) has been localized to the glandular epithelium of the prostate and stimulates the in vitro growth of prostate epithelial cells. [35S]Methionine labeling of MIF protein was used to determine if prostate cells synthesize and secrete this cytokine. The results demonstrated that the DU-145 prostate cancer cells secrete about twice the amount of a more stable protein compared with normal prostate epithelial cells. To investigate if differences in MIF mRNA levels account for the differences in MIF protein secreted by these cells, mRNA stability was analyzed by [3H]uridine incorporation. Following a 12-h pulse, DU-145 cells were found to contain four times the amount of [3H]uridine-labeled MIF mRNA, and this message exhibited a longer half-life than the message found in normal cells (33 h and 19 h, respectively). Nuclear run-on experiments confirmed that the MIF gene is transcribed at a greater rate (1.8-fold) in the DU-145 prostate cancer cells. This study documents, for the first time, that human prostate epithelial cells synthesize and secrete this cytokine. These results indicate that the increased levels of MIF found in prostate cancer cells is likely due to the increased protein and mRNA stability as exhibited by DU-145 cells.     

Cancer-specific loss of beta-defensin 1 in renal and prostatic carcinomas

In a previous large-scale gene expression profiling study of renal epithelial neoplasms, human beta-defensin-1 (DEFB1) was found to be significantly down-regulated in conventional clear cell (renal) carcinoma. We have now completed an expanded expression analysis of this gene. We performed immunohistochemical analysis for the DEFB1 protein in clinical specimens of both renal cell carcinoma and prostate cancer. In a subset of prostate cancers, we performed laser capture microdissection and RT-PCR to correlate mRNA levels with protein levels. Overall, 82% of prostate cancers exhibit either complete loss of protein expression or only minimal expression, whereas the adjacent benign epithelium retained expression in all cases. Similarly, 90% of renal cell carcinomas show cancer-specific loss of DEFB1 protein. In the prostate cancer subset analysis, mRNA levels correlate with protein levels. We have thus demonstrated the cancer-specific down-regulation of DEFB1 in a large sample of prostatic and renal carcinomas and validated one of the key findings of previous cancer gene profiling studies of prostatic and renal neoplasia.     

miR-29a抑制前列腺癌细胞恶性表型的分子机制

目的:探讨微小RNA-29a(miR-29a)在前列腺癌细胞中的生物学功能及miR-29a过表达抑制前列腺癌细胞恶性表型的分子机制。方法:运用基因芯片和生物信息学技术检测并分析miR-29a在前列腺癌组织及癌旁组织中的表达;real-time PCR检测前列腺癌组织、癌旁组织、4种前列腺癌细胞(PC3、DU145、LNCa P和Ar Ca P)及正常前列腺细胞(RWPE-1)中miR-29a和赖氨酸(K)特异性去甲基化酶4B(KDM4B)mRNA的表达水平;采用瞬时转染法将p Genesil-1-miR-29a质粒转染上述4种前列腺癌细胞,MTT法、集落形成实验、Annexin V-FITC/PI及流式细胞术分别检测细胞活力、集落形成率和细胞凋亡率;Western blot检测KDM4B的蛋白表达。结果:基因芯片和生物信息学结果显示,miR-29a在前列腺癌组织和癌旁组织中存在差异表达;real-time PCR结果显示,分别与癌旁组织和RWPE-1细胞比较,miR-29a在前列腺癌组织和4种前列腺癌细胞中的表达水平均显著降低,而KDM4B的mRNA水平显著增高(P0.05)。与阴性对照(p Genesil-1)组比较,miR-29a过表达显著抑制4种前列腺癌细胞活力和集落形成,细胞凋亡率显著增加(P0.05);Western blot结果显示,与p Genesil-1组比较,miR-29a过表达显著抑制KDM4B的蛋白表达。上调KDM4B的表达后,细胞活力明显升高,细胞凋亡率显著降低(P0.05)。结论:miR-29a在前列腺癌组织和细胞中低表达,miR-29a过表达抑制前列腺癌细胞生长,诱导细胞凋亡,其机制可能与抑制KDM4B的表达有关。     

Immunohistochemistry and in situ hybridization of the androgen receptor in the developing human prostate

 As it is suggested that the androgen receptor mechanism is required for prostatic development, we attempted to determine the appearance, expression and distribution of the androgen receptor in embryonic, infantile and pubertal human prostate. Using mono- and polyclonal antibodies and a digoxigenin-labeled 713 bp riboprobe, the androgen receptor expression in paraffin sections of fetal, infantile, and pubertal prostates was studied at the protein and RNA level. Under highly standardized conditions, application of the polyclonal antibodies resulted in a weak cytoplasmic and nuclear labeling of the epithelium of fetal glands. No immunoreaction was obtained with monoclonal antibodies. Applying the polyclonal antibody to pubertal and adult specimens, immunoreactivity of the androgen receptor was positive in nuclei of adluminal and basal epithelial cells, in interstitial and vascular smooth muscle cells and vascular endothelium, whereas ganglionic cells and enteroendocrine cells were negative. In situ hybridization with the digoxigenin-labeled riboprobe gave clear positive results already in epithelium of very young fetal specimens. A semiquantitative visual evaluation of in situ hybridizations showed that intermediate intensity of expression was increased in pubertal and adult specimens, whereas strong expression was reduced in prostatic epithelium. Conclusions: The essential findings are: (1) an early expression of androgen receptor mRNA in the fetal prostate; (2) no immunoreaction of monoclonal antibodies against the androgen receptor in the same specimens, (3) a decrease of androgen receptor mRNA expression, but increase in immunoreactivity of the androgen receptor protein with the onset of glandular maturation during puberty. Accepted: 29 September 1997     

AR-V7在前列腺癌细胞耐药中的作用

目的:探讨雄激素受体剪接变异体7(AR-V7)在前列腺癌细胞耐药中的作用及分子机制。方法:运用Lipofectamine2000转染法将AR-V7 siRNA(siAR-V7)转染至4株前列腺癌细胞中,命名为PC3-siAR-V7、DU145-siAR-V7、LNCaP-siAR-V7和ArCaP-siAR-V7细胞,以转染无关序列(NC siRNA)为阴性对照。运用real-timePCR和Westernblot实验分别检测转染前后细胞中AR-V7的mRNA和蛋白表达水平;运用MTT法和Transwell法分别检测细胞活力和细胞迁移率;运用萤光素酶报告基因实验和Western blot实验分别检测AR的启动子活性及下游靶基因前列腺特异性抗原(PSA)和FK506结合蛋白5(FKBP5)的蛋白表达。构建耐比卡鲁胺的前列腺癌细胞系LNCaP-DR,运用免疫荧光观察LNCaP、LNCaP-siAR-V7和LNCaP-DR细胞中AR和AR-V7的亚细胞定位;运用蛋白质免疫共沉淀实验检测AR-V7与热休克蛋白90(HSP90)的相互作用。结果:4株前列腺癌细胞中的AR-V7 mRNA水平显著高于正常前列腺上皮细胞RWPE-1(P0.05);PC3-siAR-V7、DU145-siAR-V7、LNCaP-siAR-V7和ArCaPsiAR-V7细胞中AR-V7蛋白水平、细胞活性及细胞迁移率显著低于NCsiRNA转染的细胞(P0.05)。随着比卡鲁胺剂量的增加,所有细胞活力逐渐降低,而下调AR-V7表达显著增强前列腺癌细胞对比卡鲁胺的敏感性(P0.05)。Westernblot结果显示下调AR-V7表达显著抑制AR启动子活性,其下游PSA和FKBP5蛋白水平明显降低(P0.05)。免疫荧光结果发现AR和AR-V7主要存在于前列腺癌细胞核内,AR少量存在于细胞质中;下调AR-V7表达则抑制AR的核转运;AR存在于耐药细胞核中,AR-V7在耐药细胞中高表达。免疫共沉淀结果显示内源性AR-V7与HSP90相互作用。结论:AR-V7在前列腺癌细胞中高表达,下调AR-V7的表达显著抑制前列腺癌细胞活力和迁移;前列腺癌细胞耐药与AR-V7高表达相关,其机制可能通过AR-V7与HSP90相互作用介导AR-V7的核转运,激活AR信号通路调控下游靶基因的转录活性最终导致细胞耐药。     

Liprin-alpha2 gene,protein tyrosine phosphatase LAR interacting protein related gene,is downregulated by androgens in the human prostate cancer cell line LNCaP

Prostate cancer is one of the most common neoplasms in the USA and Europe. We used differential display PCR (DD-PCR) to identify androgen-regulated genes in prostate cancer. The RNA of LNCaP cells treated with dihydrotestosterone (DHT) was analyzed for differentially expressed genes. Using DD-PCR, we identified a down-regulated cDNA fragment by DHT in LNCaP cells. This fragment was cloned and expressions of this fragment in prostate cancer cell lines were analyzed by RT-PCR. Sequence analysis revealed that a cDNA fragment is identical to protein tyrosine phosphatase LAR related gene, liprin-alpha2. liprin-alpha2 was downregulated by dihydrotestosterone (DHT) in LNCaP cells in a time- and androgen concentration-dependent manner. Downregulation by DHT was not inhibited by the protein synthesis inhibitor cycloheximide. This liprin-alpha2 gene was not expressed in androgen independent prostate cancer cell lines PC-3 and DU-145 at the mRNA level. And also, we first revealed here that liprin-alpha2 mRNA is expressed in LNCaP cells as well as human prostate cancer tissues and normal prostate tissues. These data suggest that liprin-alpha2 might play a role in androgen responsive human prostate cancer cell line as well as human prostate cells, and the loss of this gene expression might be associated with the androgen independent characteristics of prostate cancer.