Antagonists of growth hormone releasing hormone (GHRH) and of bombesin/gastrin releasing peptide (BN/GRP) suppress the expression of VEGF, bFGF, and receptors of the EGF/HER family in PC-3 and DU-145 human androgen-independent prostate cancers

BACKGROUND: Antagonists of growth hormone releasing hormone (GHRH) as well as antagonists of bombesin/gastrin releasing peptide (BN/GRP) inhibit the growth of various malignancies (cancers) including prostate cancer. METHODS: We investigated the effects of GHRH antagonists MZ-J-7-118 and RC-J-29-18, BN/GRP antagonists RC-3940-II and RC-3940-Et and the combination of MZ-J-7-118 and RC-3940-II on the growth of PC-3 and DU-145 human androgen independent prostate cancers xenografted s.c. into nude mice. To elucidate the mechanisms of action of these analogs, growth factors like IGF-II (insulin-like growth factor-II), vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and epidermal growth factor receptor/human epidermal growth factor receptor (EGF-R/HER) family were measured in tumors as well as IGF-I in serum. RESULTS: Antagonists of GHRH and BN/GRP alone or in combination significantly inhibited growth of PC-3 and DU-145 tumors, the greatest inhibition of tumor volume being achieved by combination of MZ-J-7-118 (5 microg/day) and RC-3940-II (10 microg/day). BN/GRP and GHRH antagonists and their combination also decreased the expression of VEGF significantly in PC-3 and non-significantly in DU-145, as measured by radioimmunoassay for VEGF protein and RT-PCR for mRNA levels of VEGF. GHRH and BN/GRP antagonists reduced bFGF concentrations and the maximal binding capacity of EGF receptors, and their mRNA levels in PC-3 and DU-145 tumors. mRNA levels for HER-2 and -3 were also diminished in PC-3 tumors by GHRH and BN/GRP antagonists. No changes in HER-4 were found after treatment. Serum IGF-I and tumoral IGF-II levels were not affected by the analogs. CONCLUSIONS: BN/GRP and GHRH antagonists inhibit growth of PC-3 and DU-145 prostate cancers by suppressing the expression of tumoral growth factors such as VEGF and bFGF as well as the receptors for EGF and related HER-2 and -3. Additive effects on tumor inhibition (TI) in vivo, but not on VEGF, bFGF, or members of the EGF/HER receptor family, can be achieved by the joint administration of both classes of analogs.     

蛙皮素对雄激素非依赖型前列腺癌细胞增殖、粘附、迁移的影响

目的 观察蛙皮素（Bombesin，BBS）及其受体拮抗剂对雄激素非依赖型前列腺癌细胞系（PC-3、DU-145）增殖、粘附、播散的影响。方法 ①四甲基偶氮唑盐微量酶反应比色法（MTT法）检测BBS及其受体拮抗剂对细胞增殖的影响；②通过计算细胞贴壁率检测BBS及其受体拮抗剂对细胞粘附能力的影响；③细胞划痕试验及Millicell小室检测BBS对细胞播散能力的影响。结果①不同浓度（10^10—10`-5mol／L）的BBS可促进细胞增殖，并呈现一定浓度依赖性，而其受体拈抗剂具有相反作用；②终末浓度10`-6—10`-5mol／L的BBS提高细胞贴壁率效果最佳，其受体拮抗剂则降低细胞贴壁率；③不同浓度的BBS可提高细胞播散能力。结论实验证明BBS可通过特异性受体介导致PC-3、DU-145细胞系增殖、粘附、播散，其拮抗剂具有相反作用。此为探索BBS及其受体拮抗剂应用于肿瘤生物学特性研究提供了基础。     

Patterns of metastasis by the human prostate cancer cell line PC-3 in athymic nude mice

Cells from the PC-3 human prostate cancer cell line were evaluated in athymic nude mice in order to determine the influence of size of the primary tumor and site inoculation on the incidence and pattern of metastasis. At autopsy, all organs, including the skeleton, were evaluated for metastasis. Subcutaneous injections resulted in metastases to the draining axillary lymph node and lungs (56% and 13%, respectively), and were correlated with size of the primary tumor. Tail vein injection resulted in a high incidence of lung metastasis, while injection into the peritoneal space, spleen, and seminal vesicles resulted in intraabdominal tumor growth, liver metastasis, and large tumors within the seminal vesicles, respectively. Skeletal metastases were not observed in any of the animals studied. We conclude that injection of PC-3 cells into various sites results in different patterns of metastasis, but may not constitute an entirely suitable animal model of human prostate cancer due to the lack of metastasis to the skeleton.     

细胞株源人前列腺肿瘤干细胞的分选与鉴定

目的:论证人前列腺癌(prostate cancer,PCa)细胞株中是否存在干细胞亚群。方法:分别用免疫表型法和侧群(side population,SP)细胞法从5种人PCa细胞株(Du145、IA8、LNCaP、TSU-PrL和PC-3)中富集类干细胞,再应用软琼脂克隆形成试验初步验证类干细胞亚群的体外生长方式及成瘤能力。选择LNCaP源SP细胞(LNCaP/SP),依次采用免疫细胞化学技术、Transwell、MTT以及裸鼠致瘤试验,分别检测其干细胞标记物的表达情况、鉴定其体外增殖和侵袭能力以及动物体内的致瘤和转移潜能。结果:5种细胞株中均难以分选出免疫表型为CD133+CD44+的细胞亚群。除PC-3外,其余4株细胞可分选出呈现典型克隆性生长特点的SP细胞。体外克隆形成率在IA8、LNCaP和TSU-PrL源SP细胞与非侧群(non-side population,NSP)细胞间有显著性差异(P<0.05)。与LNCaP/NSP相比,LNCaP/SP的体外增殖和侵袭能力显著增强,同时阳性表达整合素α2、Nanog、CD44、OCT4以及ABCG2等5种干细胞标记物。而且,LNCaP/SP的皮下成瘤率、骨转移率及瘤体体积亦显著高于LNCaP/NSP(P<0.01)。结论:SP分选法更适合富集人PCa细胞株中类干细胞,LNCaP/SP细胞是PCa细胞株LNCaP中的肿瘤干细胞(cancer stem cell,CSC)。     

The diverse and contrasting effects of using human prostate cancer cell lines to study androgen receptor roles in prostate cancer

The androgen receptor （AR） plays an important role in the development and progression of prostate cancer （PCa）. Androgen deprivation therapy is initially effective in blocking tumor growth, but it eventually leads to the hormonerefractory state. The detailed mechanisms of the conversion from androgen dependence to androgen independence remain unclear. Several PCa cell lines were established to study the role of AR in PCa, but the results were often inconsistent or contrasting in different cell lines, or in the same cell line grown under different conditions. The cellular and molecular alteration of epithelial cells and their microenvironments are complicated, and it is difficult to use a single cell line to address this important issue and also to study the pathophysiological effects of AR. In this paper, we summarize the different effects of AR on multiple cell lines and show the disadvantages of using a single human PCa cell line to study AR effects on PCa. We also discuss the advantages of widely used epithelium-stroma co-culture systems, xenograft mouse models, and genetically engineered PCa mouse models. The combination of in vitro cell line studies and in vivo mouse models might lead to more credible results and better strategies for the study of AR roles in PCa.     

参附注射液对前列腺癌PC-3细胞凋亡诱导的影响

目的:研究参附注射液(SF)对人前列腺癌PC-3细胞凋亡的影响及可能机制。方法:实验设立对照组和SF 50、100、200μl/ml组,Annexin V/PI染色流式细胞术检测细胞凋亡,RT-PCR检测p53 mRNA表达。结果:与对照组比较,作用24、48、72 h后,SF 50、100、200μl/ml组PC-3细胞存活率显著减少(P均0.05)。SF各组24 h存活率分别为(93.76±2.63)%、(81.21±1.80)%、(18.01±3.84)%;48 h存活率分别为(94.67±1.11)%、(78.33±2.89)%、(10.34±1.44)%;72 h存活率分别为(91.30±0.47)%、(36.67±1.56)%、(1.33±0.32)%,呈浓度和时间依赖性。作用48 h后,p53 mRNA表达明显升高(P0.05)。结论:SF可以诱导PC-3细胞凋亡,其作用机制可能与p53表达增高相关。     

PC-3 cells with enhanced androgen receptor signaling: a model for clonal selection in prostate cancer

BACKGROUND: Two sublines of the human prostate cancer cell line, PC-3, which is widely used as a model of prostate cancer progression, have been reported: PC-3(AR-) that do not express androgen receptor (AR), and PC-3AR+ that have measurable AR RNA but little protein. METHODS: We assayed the geneotype, karyotype, AR expression, and physical characteristics of the two PC-3 sublines, and compared their ability to elicit a transactivation response from ectopic AR in the presence and absence of specific AR coregulators. RESULTS: PC-3(AR-) and PC-3AR+ cells are genotypically and karyotypically similar, but exhibit salient differences in their morphology, growth rate, and expression of AR RNA. Whereas endogenous AR expression in PC-3AR+ cells does not result in sufficient protein to confer androgen responsiveness in culture, ectopic AR consistently elicited a much greater transactivation response in PC-3AR+ than in PC-3(AR-) cells, without altered sensitivity to activation by native ligand or AR coregulators including GRIP1, BRCA1, and Zac1. Moreover, phenotypic differences of AR variants implicated in prostate cancer susceptibility and progression were only observed in PC-3AR+ cells. Higher levels of known AR coregulator proteins detected in PC-3AR+ compared with PC-3(AR-) cells likely contribute to these differences. CONCLUSIONS: These studies provide new evidence that the androgen-signaling axis can be sensitized in prostate cancer cells, and have important implications for the analysis and interpretation of AR structure and function in in vitro cell systems.     

茶多酚对前列腺癌细胞DU145生长的影响

目的:探讨茶多酚对前列腺癌细胞生长的影响及其作用机制。方法:选取激素非依赖性前列腺癌细胞系DU145为研究对象,在药物组的培养基中加入茶多酚使其终浓度分别为50、100、250、500μg/ml,对照组加入正常细胞培养基。各组细胞培养48 h后,采用MTT比色法检测细胞生存率,然后通过Western印迹分析和荧光定量RT-PCR法检测各组细胞survivin基因表达情况。结果:加入茶多酚溶液48 h后,各药物组细胞存活率分别为0.97±0.12、0.71±0.07、0.20±0.03和0.08±0.01,与对照组相比,除50μg/ml组(P=0.42)外,其余3个药物组细胞存活率均明显低于对照组(P﹤0.01)。随茶多酚作用时间增加,各组细胞存活率呈现下降趋势,到96 h时,除50μg/ml组,其余3组细胞存活率均在5%以下。加药48 h后,对照组、100、250、500μg/ml药物组的sur-vivin表达条带灰度值分别为15 075±48、13 425±31、2 017±24、1 274±22,与对照组相比,3个药物组survivin蛋白表达均明显减少(P均﹤0.01)。另外,50、100、250、500μg/ml药物组给药48 h时的survivin mRNA量分别为0.74±0.03、0.64±0.02、0.52±0.01、0.21±0.02,均明显少于对照组(P均﹤0.01)。结论:茶多酚可以抑制前列腺癌DU145细胞的生长,且这种作用可能与survivin基因表达减少有关。     

Characterization of PacMetUT1, a recently isolated human prostate cancer cell line

BACKGROUND: Existing prostate cancer cell lines have limitations. METHODS: Cells were characterized using Western blotting, immunohistochemistry, invasion into Matrigel, and by studying xenograft tumors. RESULTS: We describe a cell line (PacMetUT1) isolated from a lymph node of a 57-year-old male with prostate cancer. Compared to existing prostate cancer cell lines, the growth rate of PacMetUT1 xenograft tumors is slower with tumors occurring at injection sites and with metastases to lung and liver. Androgen receptor (AR) was detected in vivo by Western blotting and the cells responded to methyltrienolone (R1881). PacMetUT1 cells are more invasive in Matrigel than DU-145, PC-3, and LNCaP cells, and showed greater anchorage-independent growth in soft agar. The cells do not express prostate specific antigen (PSA) in vitro or in xenografts. However, the green fluorescent protein (GFP) gene was introduced and stably expressed in PacMetUT1 cells, allowing tumor imaging in vivo. Xenograft tumors show epithelial features and are positive for keratin, epithelial membrane antigen, EGF receptor, and E cadherin. In contrast, fibroblast markers vimentin, desmin, and Factor VIII, were negative. Karyotyping showed losses of 6p, 7q, 8p, 18q, and 22q, and gains of 8q and 9q; additional genetic material was observed at 2q and 12p. CONCLUSION: The PacMetUT1 cell line allows metastases to be assessed using a single animal model. Because of its slower growth, PacMetUT1 more closely mimics the human disease. Studies of tumor progression or metastasis can be conducted over a longer period of time.     

Transactivation of epidermal growth factor receptor after heparin-binding epidermal growth factor-like growth factor shedding in the migration of prostate cancer cells promoted by bombesin

BACKGROUND: A pathway consisting of bombesin, G-protein coupling receptors (GPCRs), metalloproteases, pro-heparin-binding epidermal growth factor (proHB-EGF), and epidermal growth factor receptor (EGFR) has been reported in prostate cancer cells. The occurrence of HB-EGF shedding from proHB-EGF in this pathway, however, has not been proven directly. In addition, it is still unclear how much this pathway contributes to the migration of prostate cancer cells. In this study, we tried to directly elucidate HB-EGF shedding in this pathway and to determine its contribution to the migration of prostate cancer cells. METHODS: RT-PCR and indirect immunofluorescence staining for HB-EGF and its receptors, such as EGFR and HER4/erbB4, were performed on PC-3 cells. The influences of bombesin, anti-EGFR neutralizing monoclonal antibody, HB-EGF, and HB-EGF shedding inhibitor on the migration of PC-3 cells were studied by means of in vitro wound assays. The amount of HB-EGF shed from PC-3 cells with alkaline phosphatase-tagged HB-EGF in the presence of bombesin was determined by measuring AP activity. Immunoprecipitations and phosphotyrosine Western blotting were performed to detect EGFR transactivated by bombesin. RESULTS: PC-3 expressed HB-EGF and EGFR, but not HER4/erbB4. PC-3 migrated in the presence of bombesin, but its migration was partly inhibited by the neutralizing antibody against EGFR. PC-3 also migrated in the presence of HB-EGF, but HB-EGF shedding inhibitor partly inhibited this phenomenon. HB-EGF was shed from PC-3 cells in the presence of bombesin, and this shedding was inhibited by HB-EGF shedding inhibitor. In addition, the EGFR on PC-3 was activated in the presence of bombesin and inactivated in the presence of HB-EGF shedding inhibitor. CONCLUSIONS: These results indicated that HB-EGF shedding and the following transactivation of EGFR occurs in this pathway and that this pathway partly contributes to the migration of prostate cancer cells.     

培养液中胆固醇缺乏对前列腺癌PC-3细胞生长和凋亡的影响

目的:探讨培养液中胆固醇水平对人前列腺癌PC-3细胞生长抑制及凋亡调控的作用。方法:前列腺癌PC-3细胞分别培养于普通和胆固醇缺乏培养液中,再分别加入不同剂量血小板源性生长因子PDGF或EGF作用后,倒置显微镜观察细胞形态,MTT法检测细胞的增殖抑制情况,流式细胞仪进行细胞凋亡率及细胞周期时相分析。结果:与普通培养液组比较,胆固醇缺乏培养液组细胞明显变圆、体积缩小、脱壁细胞增多。MTT法检测显示,胆固醇缺乏培养液组细胞增殖显著抑制,并呈剂量依赖性。流式细胞分析显示胆固醇缺乏培养液组细胞凋亡率同普通培养液组相比无显著差异。当加入PDGF或EGF刺激细胞增殖时,普通培养液组细胞数目显著增加,而在胆固醇缺乏培养液组脱壁细胞增加,细胞凋亡增多,同普通培养液组相比存在显著差异。流式细胞术分析细胞周期显示,同普通培养液组相比,胆固醇缺乏培养液组停滞在G0/G1期细胞增加,而S、G2/M期细胞减少。结论:胆固醇缺乏对PC-3细胞增殖有显著抑制作用,其作用机制并不是简单增加细胞凋亡,而可能是在不利增殖条件下,PC-3细胞的一种自我调节机制。