腺病毒介导HSV-TK／GCV自杀基因系统靶向性治疗前列腺癌实验研究

目的观察腺病毒介导单纯疱疹病毒胸苷激酶基因／丙氧鸟苷（HSV-TK／GCV）自杀基因系统在人端粒酶逆转录酶（hTERT）启动子调控下对人前列腺癌细胞的靶向性体外杀伤效应。方珐利用不同感染复数（MOI）的重组腺病毒携带增强型绿色荧光蛋白（EGFP）基因感染前列腺癌细胞LNCaP和人成纤维细胞MRC-5,荧光显微镜下观察其感染效率;利用携带不同启动子的重组腺病毒Ad-hTERT-HSV／TK以及Ad-CMV-HSV／TK感染LNCaP和MRC-5细胞,加入不同浓度GCV,MTT法观察受转染细胞的存活率。结杲重组腺病毒Ad-hTERT-EGFP能特异地转染LNCaP,其转染效率随重组病毒的MOI增加而升高（P〈0.01）,MOI为1时转染率为8.3％,MOI为1000时转染率达100％;应用GCV处理后,Ad-CMV-HSV／TK对LNCaP和MRC-5细胞均有杀伤作用,而Ad-hTERTp-HsV／TK只杀伤LNcaP（P〈0.001）,随着MOI和GCV浓度的增加,LNCaP细胞存活率明显降低（P〈0.01）,MOI为1和GCV浓度为1μmol／L时存活率为95.4％,MOI为100和GCV浓度为1000μmol／L时存活率仅为6.1％,并有旁观者效应。结论重组腺病毒携带EGFP报告基因可准确、简便地确定转染效率;hTERT启动子调控的重组腺病毒介导的HSV-TK／GCV自杀基因系统对人前列腺癌细胞有靶向杀伤作用。     

Triiodothyronine modulates cell proliferation of human prostatic carcinoma cells by downregulation of the B-cell translocation gene 2

BACKGROUND: Studies suggest that triiodothyronine (T3) and cognate nuclear receptors (hTR) are involved in regulation of prostatic cell growth and differentiation. To probe mechanisms for T3 effects, we studied prostate carcinoma cells, investigating the effect of T3 on expression of the B-cell translocation gene 2 (BTG2), which regulates the G1/S transition of the cell cycle. METHODS: Effects of T3 on cell proliferation were determined by (3)H-thymidine incorporation. T3 modulation of BTG2 expression was investigated using immunoblots, Northern blots, and transient gene expression assays. The putative T3 response element was determined by electrophoretic mobility shift assay. RESULTS: T3 (0.1-1,000 nM) enhanced threefold the proliferation of prostate carcinoma cells and human androgen-dependent prostate carcinoma cells (LNCaP), but not PC-3 cells. T3 also inhibited BTG2 gene expression in LNCaP cells. Reporter assays showed that T3 downregulates by 50% promoter activity of the BTG2 gene in LNCaP cells but not PC-3 cells or thyroid-hormone receptor (TRbeta1)-overexpression PC-3 cells. Deleting the putative thyroid hormone response element (TRE; AGCGATGACCTCAGCG) blocked the inhibitory effect of T3 on BTG2 promoter activity. Electrophoretic mobility shift assays with purified TRbeta1 from in vitro translation, or with nuclear extracts from LNCaP cells and PC-3 cells, demonstrated the presence of T3 receptor binding sites in the TRE region. CONCLUSIONS: These results suggested that the T3 upregulates proliferation of LNCaP cells by downregulating BTG2 gene expression through the consensus TRE pathway.     

Inhibition of androgen-sensitive LNCaP prostate cancer growth in vivo by melatonin: association of antiproliferative action of the pineal hormone with mt1 receptor protein expression

BACKGROUND: Potential involvement of the mt1 receptor in the antiproliferative action of melatonin on androgen-sensitive LNCaP cells, and melatonin-induced modulation of androgen-insensitive PC-3 cell growth, have been reported in vitro. The effects of melatonin on prostate cancer cell proliferation and their association with mt1 receptor expression were investigated in athymic nude mice xenograft models of LNCaP and PC-3 cells. METHODS: Daily saline or melatonin (4 microg/g body weight) was given to nude mice before or after tumor cell inoculation. Tumor volume was measured periodically, and expression of PCNA, cyclin A, PSA, and mt1 receptor was assessed by immunohisto(cyto)chemistry and/or Western blotting. RESULTS: Melatonin inhibited the growth of LNCaP tumors, without affecting the growth of PC-3 xenografts, in nude mice. It induced significant decreases in the expression of PCNA, cyclin A, and PSA in LNCaP tumors. Expression of mt1 receptor protein was demonstrated in LNCaP cells, but not in PC-3 cells, both in vivo and in vitro. CONCLUSIONS: The antiproliferative action of melatonin on LNCaP tumor growth was demonstrated in vivo, and its association with mt1 receptor protein expression suggests the potential involvement of the receptor in the antitumor activity of the pineal gland hormone.     

携带报告基因EGFP的CXCR4 RNA干扰质粒的构建及生物活性的鉴定

目的构建携带报告基因EGFP的CXCR4RNA干扰质粒,证实其高效抑制靶基因表达的生物活性。方法设计有发夹状结构的两条DNA序列,用PCR扩增CXCR4特异性小干扰RNA(smallinterferingRNA,siRNA),转入带有增强型绿色荧光蛋白(EGFP)和启动子U6的pGensil-1质粒,转化DH5a菌株,提取质粒行酶切及测序鉴定。重组质粒转染PC-3m细胞株,检测绿色荧光蛋白表达及对细胞CXCR4表达的抑制情况。结果成功构建了CXCR4靶向的RNA干扰质粒pGensil-1/siCXCR4,在靶细胞可同时表达siRNA及绿色荧光蛋白。结论pGensil-1/siCXCR4质粒的成功构建对利用基因干扰技术治疗前列腺癌转移方面的研究奠定了一定的实验基础。     

Inhibition of telomerase is related to the life span and tumorigenicity of human prostate cancer cells.

PURPOSE: Telomerase, the enzyme that catalyzes the elongation of telomeres, is illegitimately activated in the majority of cancers, including that of the prostate, where it may greatly extend the life span of malignant cells. The inhibition of telomerase by molecular intervention has been shown to lead eventually to cell death in several tumor or in vitro immortalized cell lines and in 1 case prevent tumor growth in vivo. Therefore, we tested whether a similar strategy may be used to limit the tumorigenic potential of late stage prostate cancer cells. MATERIALS AND METHODS: PC-3, LNCaP and DU-145 human prostate cancer cells were infected with a retrovirus encoding a dominant-negative version of the catalytic subunit of telomerase (DN-hTERT). Subclones or polyclonal populations were assayed for DN-hTERT expression, telomerase activity, telomere length, cell life span and in most cases tumorigenicity in nude mice. RESULTS: DN-hTERT expression levels directly correlated with cell life span and tumorigenic growth. PC-3 cells expressing high levels of DN-hTERT died rapidly and failed to form tumors in nude mice, whereas cells expressing the lowest levels proliferated the longest and generated tumors that later spontaneously regressed. Similarly the inhibition of telomerase activity in LNCaP cells was greater than in DU-145 cells and correspondingly LNCaP cells had a shorter life span. CONCLUSIONS: DN-hTERT expression limits the life span and tumorigenic potential of human prostate cancer cells, although the onset of these effects appears to be dictated by the expression level of DN-hTERT. Therefore, telomerase represents an attractive target for potentially managing prostate cancer. Nevertheless, effective means of inhibiting the enzyme may be required for a therapeutically useful outcome.     

Human prostate cancer cells express neuroendocrine cell markers PGP 9.5 and chromogranin A

BACKGROUND: A proportion of men with prostate cancer will progress to develop metastatic disease involving the lymph-nodes and bone. To identify novel candidates associated with metastatic progression, we compared the proteomic profiles of LNCaP (lymph-node metastatic, androgen-dependant) and PC-3 (bone metastatic, androgen-independent), human prostate cancer cells. METHODS: Two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), followed by electrospray ionisation tandem mass spectrometry (ESI-MS/MS), was used to identify differentially expressed proteins. Western blotting was used to validate the identity of any candidates. Immunohistochemistry was used to assess tissue expression. RESULTS: 2D-PAGE followed by ESI-MS/MS analyses identified the expression of glutathione S-transferase-pi (GST-pi) and protein gene product 9.5 (PGP 9.5) in PC-3 cells, but absent expression in LNCaP cells. PGP 9.5 expression in PC-3 cells was confirmed by Western blotting, in addition to expression in DU145 cells. Analysis of cell conditioned media showed that PGP 9.5 was secreted. Sequencing of the PGP 9.5 gene promoter region in bisulfite modified DNA, suggested that the regulation of expression involves promoter hypermethylation. RT-PCR analysis for Chromogranin A (ChA) mRNA (a marker of neuroendocrine cells), showed expression in PC-3 and DU145 cells but was undetectable in LNCaP cells. Immunohistochemistry localised PGP 9.5 expression exclusively within neuroendocrine cells and nerve fibres. CONCLUSIONS: Our unexpected finding that the neuroendocrine cell markers PGP 9.5 and ChA are expressed by PC-3 and DU145 cells, suggests that these cells may have been derived from metastatic adenocarcinomas which had undergone neuroendocrine differentiation or alternatively the expression occurred ectopically as a result of cell culture.     

Reduction of wild type p53 function confers a hormone resistant phenotype on LNCaP prostate cancer cells

BACKGROUND: The protein encoded by the p53 gene is required for some forms of apoptosis and loss or mutations in this gene are found with increased frequency in advanced and hormone resistant human prostate cancers. In order to better appreciate whether reduction of wildtype p53 function in prostate cancer cells might contribute to the development of therapeutic-resistance by these cells, we created stable variants of the androgen-responsive, wild type p53-expressing human prostate cancer cell line, LNCaP, by transfection with expression vectors designed to reduce expression or function of wildtype p53 in them. These cells were then tested for their ability to form tumors in castrated male nude mice. METHODS: A conditional eukaryotic expression vector (under tetracycline regulation) expressing antisense p53 cDNA was constructed and either directly transfected into LNCaP cells or tranduced into these cells using recombinant retroviruses containing the vector. Stably transfected/transduced cells (LNCaP/Asp53) were evaluated by Western blot analysis for the ability of doxycycline to reduce p53 protein expression and for their ability to form tumors in castrated male nude mice treated or untreated with doxycycline. Additionally, we derived an LNCaP subline (LNCaP/DD) stably expressing a dominant-negative form of p53 and tested these cells for their ability to form tumors in castrated male nude mice. RESULTS: LNCaP/Asp53 cells showed reduced expression of p53 protein when cultured in a medium containing doxycycline and tested sublines were able to efficiently form tumors in castrated male nude mice only when the mice were treated with doxycycline. LNCaP/DD cells were readily able to form tumors in castrated male nude mice whereas parental LNCaP cells or control-transfected LNCaP cells were not. CONCLUSION: Loss of wildtype p53 function can contribute to the phenotype of hormone resistance of prostate cancer cells.     

Expression of a model gene in prostate cancer cells lentivirally transduced in vitro and in vivo

In a preclinical model for prostate cancer gene therapy, we have tested lentiviral vectors as a practical possibility for the transfer and long-term expression of the EGFP gene both in vitro and in vivo. The human prostate cancer cell lines DU145 and PC3 were transduced using experimental conditions which permitted analysis of the expression from a single proviral vector per cell. The transduced cells stably expressed the EGFP transgene for 4 months. After injection of the transduced cell populations into Nod-SCID mice a decrease in EGFP was only observed in a minority of cases, while the majority of tumors maintained transgene expression at in vitro levels. In vivo injection of viral vector preparations directly into pre-established subcutaneous or orthotopic tumor masses, obtained by implantation of untransduced PC3 and DU145 cells led to a high transduction efficiency. While the efficiency of direct intratumoral transduction was proportional to the dose of virus injected, the results indicated some technical limitations inherent in these approaches to prostate cancer gene therapy.     

Survivin启动子驱动腺病毒介导LRIG1基因治疗前列腺癌的体外实验

目的 由于去势抵抗性前列腺癌（CRPC）缺乏有效治疗方法,因此催生了探索新治疗模式的需求,其中靶向基因治疗可能是治疗CRPC的较理想模式;但是CRPC的靶向性基因治疗尚没有受到应有的关注.本课题拟研究Survivin启动子驱动的重组腺病毒Ad-Surp-LRIGl对前列腺癌细胞株的体外治疗效果.方法 用Ad-Surp-LRIGl和Ad-LRIGl分别感染人前列腺癌细胞PC-3M及人前列腺上皮细胞CRL-11609 RWPE-1,根据报告基因EGFR表达的不同计算病毒的细胞转染率.MTT法评估Ad-Surp-LRIGl和Ad-LRIGl对PC-3M细胞生长的抑制作用.结果 当MOI=25时,Ad-Surp-LRIGl在PC-3M细胞中的转染效率为81.24%,在CRL-11609 RWPE-1细胞中转染率为0,在两种细胞内的转染率比较差异有显著性意义（χ2=65.18,P=0.000）;Ad-LRIGl在PC-3M细胞中的转染效率为77.22%,在CRL-11609 RWPE-1细胞中转染率为71.68%,转染率比较差异无显著性意义（χ2=0.051,P=0.802）.Ad-Surp-LRIGl和Ad-LRIGl在PC-3M细胞中的转染率相比,差异无显著性意义（χ2=0.013,P=0.796）.在常规培养1d 后PBS组的细胞生长速度即开始超过Ad-Surp-LRIGl组和Ad-LRIGl组细胞,4 d 后细胞生长速度差异显著（χ2=15.37,P=0.001）,而Ad-Surp-LRIGl组和Ad-LRIGl组细胞生长速度无明显差异.结论 Ad-Surp-LRIGl能选择性转染人前列腺癌细胞PC-3M,能明显抑制体外前列腺癌细胞的生长.     

γ-干扰素对前列腺癌细胞粘附和侵袭能力影响的初步研究

目的：探讨γ-干扰素对前列腺癌细胞粘附和侵袭行为的影响。方法：用纤维粘连蛋白和层粘连蛋白处理细胞培养板，检测γ-干扰素对前列腺癌细胞系LNCaP和PC-3粘附作用的影响；用Transwell小室，以Matrigel和纤维粘连蛋白构建基底膜，检测γ-干扰素对前列腺癌细胞侵袭人工基底膜能力的影响；应用Western-blot法检测γ-干扰素对前列腺癌细胞膜粘连蛋白-2（annexin-2）表达的影响。结果：γ-干扰素未处理的两种人前列腺癌细胞系细胞LNCaP、PC-3粘附率分别为46％和40％，γ-干扰素处理的两种细胞系细胞LNCaP、PC-3粘附率分别为21％和23％，同种细胞系γ-干扰素处理组与未处理组间差异有显著性（P均〈0．05）。在相同细胞系γ-干扰素处理组较未处理组前列腺癌细胞24h侵袭能力明显降低（P均〈0．05）。Western印迹结果表明γ-干扰素可显著抑制annexin-2蛋白的表达（P〈0．05）。结论：γ-干扰素可能通过下调annexin-2的表达来抑制前列腺癌细胞的粘附和侵袭。     

Comparison of [18 F]fluorocholine and [18 F]fluorodeoxyglucose for positron emission tomography of androgen dependent and androgen independent prostate cancer

PURPOSE: Positron emission tomography (PET) imaging is used for the metabolic evaluation of cancer. [18F]fluorodeoxyglucose (FDG) is commonly used as a radiotracer but its low cellular uptake rate in prostate cancer limits its usefulness. We evaluated the novel choline analog [18F]fluorocholine (FCH) for detecting androgen dependent and androgen independent prostate cancer, and its metastases. MATERIALS AND METHODS: The cellular uptake of FCH and FDG was compared in cultured prostate cancer cells (LNCaP and PC-3). FCH and FDG were injected into nude mice xenografts (CWR-22 and PC-3) and radiotracer uptake in various organs were evaluated. Patients with androgen dependent (9) and independent (9) prostate cancer were studied by FCH and FDG PET. RESULTS: FCH uptake was 849% and 60% greater than FDG uptake in androgen dependent (LNCaP) and independent (PC-3) cells, respectively. The addition of hemicholinium-3 (5 mM.) 30 minutes before radiotracer administration inhibited FCH uptake by 79% and 70% in LNCaP and PC-3 cells, respectively, whereas FDG uptake was not significantly affected. Although nude mice xenografts showed that FDG uptake was equal to or greater than FCH uptake, clinical imaging in patients demonstrated 2 to 4-fold higher uptake of FCH in those with androgen and androgen independent prostate carcinoma (p <0.001). More lesions were detected by FCH than by FDG in primary tumors, osseous metastases and soft tissue metastases. CONCLUSIONS: In vitro data demonstrated greater FCH than FDG uptake in androgen dependent (LNCaP) and androgen independent (PC-3) prostate cancer cells. Although the murine xenograft data showed greater accumulation of FDG than FCH in PC-3 tumors, PET in humans showed that FCH was better than FDG for detecting primary and metastatic prostate cancer. Overall the data from this study suggest that FCH is preferable to FDG for PET of prostate carcinoma and support the need for future validation studies in a larger number of subjects.     

Lentivirus-mediated SMO RNA interference inhibits SMO expression and cell proliferation,and affects the cell cycle in LNCaP and PC3 cancer cell lines

Smoothened （SMO） is an important member of the Hedgehog signaling pathway. We constructed a specific recombinant lentiviral vector for RNA interference,targeting the SMO gene （NM_005631） to observe its effect on SMO expression,cell proliferation and the cell cycle in the human androgen-sensitive prostate cancer cell line,LNCaP,and in the androgen-independent prostate cancer cell line,PC3. Four siRNA sequences were designed and inserted into a lentiviral vector pGCSIL-GFP to construct four recombinant vectors. The vector with the highest interfering efficiency was co-transfected with packaging vectors （pHelper1.0 and pHelper2.0） in 293T cells to assemble lentivirus particles by liposome for infecting LNCaP and PC3 cell lines,respectively. The expression level of SMO mRNA,tumor cell proliferation and cell cycle were measured by quantitative realtime polymerase chain reaction （qRT-PCR）,3-（4,5）-dimethylthiahiazo （-z-yl）-3,5-di-phenytetrazoliumromide （MTT） assay and flow eytometry,respectively. Sequence results showed that recombinant lentiviral vectors were constructed successfully.pGCSIL-GFP-723 had the highest interfering efficiency,named Lv-SIL-SMO723 after co-transfection,with which LNCaP and PC3 cell lines were infected. Compared with the control groups,results showed significantly decreased （P〈0.05） SMO mRNA expressions of LNCaP and PC3,lower mean percentage of S-phase cells and higher mean percentage of G_2/M phase cells,as well as obviously slow proliferation （P〈0.01） of LNCaP in the infected group. Yet,the proliferation of PC3 was not altered （P〉0.05）. In conclusion,the recombinant lentivirus particles were able to suppress SMO expression,regulate the cell cycle in the LNCaP and PC3 cell lines and markedly inhibit proliferation of LNCaP cells but not PC3 cells.     

PC-SPES: a unique inhibitor of proliferation of prostate cancer cells in vitro and in vivo

BACKGROUND: Management of prostate cancer that has spread beyond the capsule is a difficult problem. Innovative and nontoxic approaches to the disease are urgently required. Recently, a commercially available herbal mixture called PC-SPES showed potent antitumor activities on a variety of malignant cells in vitro. METHODS: PC-SPES was evaluated for its ability to inhibit clonal growth, and to induce cell cycle arrest of three human prostate cancer cell lines (LNCaP, PC-3, and DU 145). Western blot analysis examined the effect of PC-SPES on levels of p21(waf1), p27(kip1), Bcl-2, and E-cadherin in the three cell lines; and telomerase activity was examined by telomeric repeat amplification protocol (TRAP) assay. Furthermore, the effect of oral PC-SPES (250 mg/kg/day) on growth of PC-3 and DU 145 tumors present in male BNX nu/nu triple immunodeficient mice was studied. LNCaP cells were not analyzed in mice because they grow only with difficulty in these immunodeficient mice. RESULTS: PC-SPES markedly inhibited clonal growth of LNCaP, PC-3, and DU 145 prostate cancer cells, with a 50% inhibition (ED50) at approximately 2 microl/ml. Pulse-exposure studies showed that a 5-day pulse-exposure to PC-SPES (2 microl/ml) in liquid culture achieved a 50% inhibition of PC-3 clonal growth in soft agar, suggesting that the growth inhibition mediated by the extracts remained after removal of PC-SPES. Cell cycle analysis using the prostate cancer cell lines found that PC-SPES induced a significant increase in the number of cells in G0-G1 and G2/M, with a concomitant decrease in the number of cells in S phase. PC-SPES (2 microl/ml, 4 days) increased slightly the levels of p21(waf1) in the three cell lines, decreased by 40% the levels of Bcl-2 in PC-3, and the levels of p27(kip1) and E-cadherin and telomerase were unchanged in each of the lines. In vivo treatment with oral PC-SPES of male BNX mice having DU 145 tumors produced significant inhibition of their growth (P < 0.001), with no objective side effects including blood chemistries, weights, or autopsy analysis. The PC-SPES showed no statistical effect on the in vivo growth of PC-3 cells. CONCLUSIONS: PC-SPES inhibits clonal proliferation of human prostate cancer cells both in vitro and in vivo, using a murine model.     

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.     

应用RNA干扰技术阻断PC-3细胞中survivin基因的表达

目的:用真核转录载体pS ilencerTM3.1-H1 neo构建针对survivin基因的重组真核转录载体,并转染前列腺癌细胞系PC-3,通过RNA干扰(RNA i)阻断PC-3细胞中survivin基因的表达,并研究survivin基因沉默后对PC-3细胞凋亡产生的影响。方法:将合成的DNA正义链及反义链变性、退火,形成的双链DNA与pS ilencerTM3.1-H1 neo线性质粒用T4DNA连接酶连接,重组质粒经酶切及DNA测序鉴定后,用脂质体法转染PC-3细胞,通过RT-PCR、免疫印迹和免疫组织化学染色实验检测survivin的表达变化,并用流式细胞术检测转染后PC-3细胞的凋亡变化,MTT法检测细胞生长速度的变化。结果:酶切及测序证实设计合成的DNA已正确插入载体。RT-PCR、免疫印迹和免疫组织化学染色实验表明,pS ilencer3.1-SVV2和pS ilencer3.1-SVV3重组载体有效地阻断了PC-3细胞中survivin基因的表达,survivin基因在mRNA和蛋白水平上的表达明显下调(P<0.01),转染后PC-3细胞的凋亡增加了10%~15%,细胞生长速度明显变慢。结论:成功构建了针对survivin基因的真核转录载体pS ilencer3.1-SVV1、pS ilencer3.1-SVV2和pS ilencer3.1-SVV3,后两者可有效地阻断前列腺癌细胞系PC-3细胞中survivin基因的表达,并使转染后PC-3细胞的凋亡增加了10%~15%,细胞生长速度明显变慢。