去雄激素协同辐射诱导前列腺癌细胞凋亡及凋亡通路基因的表达

目的 研究辐射和去雄激素对前列腺癌细胞凋亡通路基因表达的影响，探讨其协同诱导凋亡的机制。方法 辐射与去雄激素作用前列腺癌细胞LNCaP，MTT实验和凋亡细胞染色分别评价细胞毒性和诱导凋亡作用。收集细胞提取总RNA并合成cDNA探针，在凋亡通路特异基因cDNA膜上进行杂交反应检测基因mRNA表达，并以RT-PCR确认有关基因mRNA表达。结果 辐射与去雄激素可协同诱导前列腺癌细胞凋亡。辐射使DFFA、LTbR、mdm2、Myd88、TNFRSF8Ⅱ、TNFRSF14和TNFSF4基因mRNA表达上调，使Survivin和Bar基因mRNA表达下调。去雄激素使Mcl-1、TNFRSF14、MyD88和TNFSF4基因mRNA表达上调，使Bar、Survivin和TRAIL—R3基因mRNA表达下调。结论 去雄激素和辐射对前列腺癌细胞凋亡通路基因的表达改变不同，这与两者协同诱导凋亡作用有关。     

Novel therapeutic strategy for advanced prostate cancer using antisense oligodeoxynucleotides targeting anti-apoptotic genes upregulated after androgen withdrawal to delay androgen-independent progression and enhance chemosensitivity

Progression to androgen-independence remains the main obstacle to improving survival for patients with advanced prostate cancer. In this review, findings are summarized that have recently been demonstrated to establish novel therapeutic strategy targeting several genes playing functionally important roles after androgen withdrawal and during androgen-independent progression. The authors initially characterized changes in gene expression after androgen withdrawal in the androgen-dependent Shionogi and LNCaP tumor models using cDNA arrays. Based on these results, they focused on genes highly upregulated after androgen ablation (i.e. bcl-2, bcl-xL, TR.PM-2, IGFBP-5), which have anti-apoptotic or mitogenic activities, and thereby confer a resistance to androgen withdrawal as well as cytotoxic chemotherapy. The authors further demonstrated the efficacy of an antisense oligodeoxynucleotide (ODN) strategy for patients with advanced prostate cancer through the inhibition of target gene expression, resulting in a delay in the progression to androgen-independence by enhancing apoptotic cell death induced by androgen ablation and chemotherapy. The authors also showed the effectiveness of combined antisense ODN therapy and cytotoxic chemotherapy by achieving additive or synergistic effects. These findings provide a basic significance for the design of clinical studies using antisense ODN either alone or in combination with chemotherapeutic agents in patients with advanced prostate cancer.     

前列腺癌细胞凋亡通路基因表达与凋亡反应性的关系

目的　探讨凋亡通路基因表达改变与前列腺癌细胞凋亡反应性的关系。　方法　凋亡诱导剂鬼臼乙叉甙分别作用前列腺癌激素敏感与不敏感细胞LNCaP和PC 3,Hoechst 332 5 8染色检测凋亡发生率。收集LNCaP和PC 3细胞后提取总RNA ,合成cDNA探针并以生物素标记 ,在凋亡通路特异基因寡核苷酸片段cDNA膜上进行杂交反应 ,检测基因mRNA表达。　结果　鬼臼乙叉甙能诱导两种细胞凋亡 ,但PC 3细胞的凋亡反应性小于LNCaP细胞。与LNCaP细胞比较 ,PC 3细胞显著下调的基因为Bcl1 0、CIDE A、GADD4 5a和RIP2 ,以及Caspase 4、5和 6 ,显著上调的基因为TRAF4。两种细胞均强烈表达Caspase 1 4和TNFR2。　结论　凋亡通路基因表达改变与前列腺癌细胞凋亡反应性不同有关 ,在前列腺癌激素敏感性转化中可能有重要作用     

Prostate cancer cells generated during intermittent androgen ablation acquire a growth advantage and exhibit changes in epidermal growth factor receptor expression

BACKGROUND: Intermittent androgen ablation is a palliative treatment option for advanced prostate cancer which is associated with less side effects, improved quality of life of patients, and reduced costs. Regulation of growth and survival of prostate cancer cells during intermittent androgen withdrawal has not been studied in appropriate models yet. METHODS: Two cycles of androgen withdrawal and supplementation were performed in human prostate cancer cells LNCaP in vitro. Proliferation of prostate cancer cell sublines established after intermittent androgen withdrawal was assessed in the absence or presence of epidermal growth factor (EGF) by protein determination. Cell cycle was analyzed with a flow cytometer. EGF was measured in the supernatants of LNCaP sublines with a commercial ELISA. EGF receptor mRNA and protein were determined by real-time PCR and Western blot, respectively. RESULTS: Basal proliferation rate of all newly generated LNCaP sublines increased over that of the parental LNCaP cell line. The highest stimulation of proliferation by exogenous EGF was observed in parental LNCaP cells. In each LNCaP derivative established during intermittent androgen withdrawal, the percentage of cells in the S phase of cell cycle was higher than that in parental LNCaP cells. EGF levels did not increase during intermittent androgen ablation. The expression of EGF receptor protein decreased following each cycle of androgen ablation and increased subsequently after androgen supplementation. EGF receptor (EGFR) mRNA was regulated in a similar manner in LNCaP derivatives established during the second cycle of intermittent withdrawal. CONCLUSIONS: Changes in the expression of the EGF receptor occur during intermittent androgen ablation but they cannot be solely responsible for increased basal proliferation. Alternatively, other ligands and receptors of the EGF system may become overexpressed during prolonged withdrawal and supplementation of androgenic hormones in prostate cancer therapy.     

Epigallocatechin-3-gallate and bicalutamide cause growth arrest and apoptosis in NRP-152 and NRP-154 prostate epithelial cells

AIM: A number of epidemiological studies have suggested that consumption of green tea reduces the risk of prostate cancer. The aim of this study was to elucidate the effects of epigallocatechin-3-gallate (EGCG), one of the major constituents of green tea, on growth inhibition and apoptosis in prostate epithelial cell lines with and without bicalutamide. METHODS: The effects of EGCG and bicalutamide alone and in combination were examined on NRP-152 and NRP-154 cells derived from the dorso-lateral prostate of the Lobund-Wistar rat. Following treatments, cell number and levels of apoptosis were assessed. RESULTS: After treatment with EGCG, both cell lines displayed a dose-dependent decrease in cell number; this effect was more pronounced in NRP-154 cells. This decrease in cell number was caused by growth arrest in NRP-152 cells and apoptosis in NRP-154 cells. The apoptotic events in the NRP-154 cells were concurrent with a loss of manganese superoxide dismutase expression. Androgen ablation was achieved by androgen withdrawal using charcoal stripped serum or treatment with bicalutamide. Bicalutamide decreased cell number and induced apoptosis in a dose-dependent manner in both cell lines; however, androgen withdrawal did not. There was a loss of androgen receptor expression in NRP-152 cells with bicalutamide treatment. However, as the NRP-154 cells are androgen receptor negative, the loss in cell number and increased apoptotic events in these cells cannot be attributed to the anti-androgenic activity of bicalutamide. Cells treated with a combination of bicalutamide and EGCG also demonstrated a dose-dependent decrease in cell number that was significantly greater than bicalutamide alone. CONCLUSIONS: This study demonstrates the potential use of EGCG and other antioxidants as therapeutic candidates for prostate cancer.     

Clusterin expression is significantly enhanced in prostate cancer cells following androgen withdrawal therapy

INTRODUCTION AND OBJECTIVES: Progression of prostate cancer to androgen independence (AI) results in part from the upregulation of anti-apoptotic genes following androgen withdrawal, and androgen-independent disease remains the primary obstacle to improved survival. Testosterone-repressed prostate message-2 (TRPM-2) encodes the anti-apoptotic protein clusterin, which is upregulated in response to cellular compromise as observed in normal and malignant tissues undergoing apoptosis. Systemic administration of antisense clusterin oligonucleotides in prostate cancer xenograft models delays progression to AI and enhances chemosensitivity. The objective of this study was to define changes in clusterin expression following neoadjuvant hormone therapy (NHT) in prostate cancer patients. MATERIALS AND METHODS: Archival radical prostatectomy (RP) specimens were obtained for 128 patients who received either no NHT or treatment for 2-8 weeks, 3 months, or 8 months. Paired needle biopsy specimens were acquired for 30 patients and all tissues were subjected to clusterin immunohistochemistry. Western blot analysis was performed on frozen tissue from 5 untreated and 5 treated patients. RESULTS: Clusterin expression in malignant prostatic tissue was significantly greater in patients who underwent preoperative NHT (P < 0.001). Needle biopsies obtained prior to NHT consistently demonstrated lower staining intensity than corresponding RP specimens (P < 0.001). Western blot analysis confirmed clusterin levels increased 17-fold beginning within 4 weeks after androgen withdrawal. CONCLUSIONS: Upregulation of clusterin levels following androgen ablation therapy may represent an adaptive cell survival response following apoptotic signals like androgen withdrawal. These findings support clusterin as a valid therapeutic target in strategies employing novel multimodality therapy for advanced prostate cancer.     

雄激素依赖性前列腺癌细胞在其雄激素受体阻断后细胞周期基因表达的改变

目的　测定前列腺癌细胞系LNCaP在雄激素受体 (AR)阻断前后细胞周期基因表达的变化 ,探讨AR对细胞周期基因表达的影响。方法　在LNCaP细胞中加入氟他胺 ,然后抽提正常LNCaP细胞和加入氟他胺的LNCaP细胞中的mRNA制备cDNA探针 ,应用基因芯片技术观察两者细胞周期基因表达差异情况。结果　TRIZOL法提取细胞mRNA合格 ,从 8465个点位中筛选出差异表达基因共 3 2 6个 ,占 3 .93 % ;其中 97条下调 ,2 19条上调。其中与细胞周期明显相关的共有 8条基因 ,分别为CDC10、NRAS、BTG1、Wee1hu、CLK3、DKFZP5 64A12 2、CDKN1A和Btg2。其中尤以Btg1和CDKN1A表达水平较高。结论　雄激素受体在前列腺癌细胞中对细胞周期有着巨大影响。雄激素受体引起的前列腺癌细胞周期变化有多种基因参与。其中 ,CDKN1A基因和Btg1基因作用较大 ,并可能以p5 3非依赖途径作用于前列腺癌细胞。     

Clusterin is not essential for androgen-regulated involution and regeneration of the normal mouse prostate

BACKGROUND: Inhibition of clusterin expression has been shown to enhance the sensitivity of prostate cancer cells to chemo and hormone therapy. Clusterin antisense oligonucleotides (ASOs) are currently in phase II human clinical trials for treatment of hormone refractory prostate cancer. However, the role of clusterin in androgen-regulated involution and regeneration of the normal prostate gland has not been established. METHODS: Prostate involution and regeneration was examined in clusterin-deficient mice undergoing up to three cycles of androgen withdrawal and restoration. RESULTS: Surprisingly, clusterin deficiency did not affect the apoptotic index, and the temporal biochemical and morphological changes associated with involution and regeneration of the normal adult prostate following multiple rounds of androgen withdrawal and replacement. CONCLUSION: Clusterin is not critical for normal prostate development or androgen-regulated involution and regrowth of the mouse prostate gland, suggesting that clusterin may have distinct functions in malignant versus normal prostatic epithelial cells.     

Androgen receptor-dependent regulation of Bcl-xL expression: Implication in prostate cancer progression

BACKGROUND: Recently we reported that silencing the androgen receptor (AR) gene reduced Bcl-xL expression that was associated with a profound apoptotic cell death in prostate cancer cells. In this study we further investigated AR-regulated Bcl-xL expression. METHODS: Prostate cancer cell line LNCaP and its sublines, LNCaP/PURO and LNCaP/Bclxl, were used for cell proliferation assay and xenograft experiments in nude mice. Luciferase gene reporters driven by mouse or human bcl-x gene promoter were used to determine androgen regulation of Bcl-xL expression. RT-PCR and Western blot assays were conducted to assess Bcl-xL gene expression. Chromatin immunoprecipitation assay was performed to determine AR interaction with Bcl-xL promoter. Bcl-xL-induced alteration of gene expression was examined using cDNA microarray assay. RESULTS: In cultured prostate cancer LNCaP cells, androgen treatment significantly increased Bcl-xL expression at mRNA and protein levels via an AR-dependent mechanism. Promoter analyses demonstrated that the AR mediated androgen-stimulated bcl-x promoter activation and that the AR interacted with bcl-x promoter. Enforced expression of Bcl-xL gene dramatically increased cell proliferation in vitro and promoted xenograft tumor growth in vivo. Genome-wide gene profiling analysis revealed that Bcl-xL expression was significantly higher in metastatic and castration-resistant diseases compared to normal prostate tissues or primary cancers. Bcl-xL overexpression significantly increased the expression of cyclin D2, which might be responsible for Bcl-xL-induced cell proliferation and tumor growth. CONCLUSIONS: Taken together, our data strongly suggest that androgen stimulates Bcl-xL expression via the AR and that increased Bcl-xL expression plays a versatile role in castration-resistant progression of prostate cancer.     

Small interference RNA targeting heat-shock protein 27 inhibits the growth of prostatic cell lines and induces apoptosis via caspase-3 activation in vitro

OBJECTIVES: To evaluate synthetic small interference RNA (siRNA) compounds targeting heat-shock protein 27 (Hsp27) as an alternative approach to Hsp27 'knockdown' in prostate cancer cells, as Hsp27 expression is highly up-regulated in prostate cancer cells after androgen withdrawal or chemotherapy, to become uniformly highly expressed in androgen-independent (AI) prostate cancer. MATERIALS AND METHODS: We recently showed that targeting Hsp27 by a 2'-methoxyethyl modified phosphorothioate antisense oligonucleotide, OGX-427, inhibits Hsp27 expression and enhances hormone- and chemotherapy in prostate cancer xenograft models. In the present study, a 'gene walk' screening different siRNAs was initially used in PC-3 and LNCaP cells to determine the most potent sequence to down-regulate Hsp27 mRNA and protein levels. The effects of Hsp27 silencing on in vitro growth rates were studied by tetrazolium-blue and crystal violet assays. Apoptosis was determined by single-stranded DNA nuclear and cleaved caspase-3 immunostaining, as well as flow cytometry. Spotted microarrays with 14,000 human oligonucleotides were used to examine changes in gene expression. RESULTS: Low concentrations of 1 nm siRNA decreased Hsp27 mRNA levels by 19-fold and suppressed protein expression to undetectable levels. Silencing of Hsp27 in prostate cancer cells by siRNA # 2 increased apoptotic rates 2.4-4 fold and caused 40-76% inhibition of cell growth in LNCaP and PC-3 cells. Characteristic cleavage of caspase-3 occurred after treatment with Hsp27 siRNA (1 nm). cDNA microarray analysis from LNCaP and PC-3 cell lines revealed differential gene expression profiles after Hsp27 down-regulation that could be used to identify various survival pathways involved in androgen-dependent and AI growth. CONCLUSIONS: These findings illustrate the potential utility of Hsp27-silencing therapy and highlight Hsp27 siRNA strategies as a novel and highly effective tool, with the potential for future targeted therapy in enhancing the efficacy of chemotherapy in advanced prostate cancer.     

KLK31P is a novel androgen regulated and transcribed pseudogene of kallikreins that is expressed at lower levels in prostate cancer cells than in normal prostate cells

BACKGROUND: Fifteen human tissue kallikrein (KLK) genes have been identified as a cluster on chromosome 19. KLK expression is associated with various human diseases including cancers. Noncoding RNAs such as PCA3/DD3 and PCGEM1 have been identified in prostate cancer cells. METHODS: Using massively parallel signature sequencing (MPSS) technology, RT-PCR, and 5' rapid amplification of cDNA ends (RACE), we identified and cloned a novel gene that maps to the KLK locus. RESULTS: We have characterized this gene, named as KLK31P by the HUGO Gene Nomenclature Committee, as an unprocessed KLK pseudogene. It contains five exons, two of which are KLK-derived while the rest are "exonized" interspersed repeats. KLK31P is expressed abundantly in prostate tissues and is androgen regulated. KLK31P is expressed at lower levels in localized and metastatic prostate cancer cells than in normal prostate cells. CONCLUSIONS: KLK31P is a novel androgen regulated and transcribed pseudogene of kallikreins that may play a role in prostate carcinogenesis or maintenance.     

Radiation Therapy Oncology Group P-0014: a phase 3 randomized study of patients with high-risk hormone-naive prostate cancer: androgen blockade with 4 cycles of immediate chemotherapy versus androgen blockade with delayed chemotherapy

Currently, approximately 30,000 men die annually of metastatic, hormone-refractory prostate cancer. Androgen blockade is palliative and is generally effective for an average of 2 to 3 years until a patient develops androgen-independent disease. Newer chemotherapeutic regimens can induce remissions in approximately 50% of patients; however, median survival for patients with androgen-independent disease is still 8 to 12 months. The strategy of using chemotherapy regimens after androgen blockade has been proved noncurative, and new approaches are needed to attempt to cure patients with advanced disease. It has been demonstrated in the preclinical setting that androgen withdrawal induces apoptosis in cancer cells in both the Shinogi breast cancer model and the LNCaP prostate cancer model. In both of these models, androgen withdrawal was not curative, and the tumors grew back in a hormone-independent state. It is possible that the addition of chemotherapy at the time of initial androgen ablation will improve cell kill by potentiating apoptosis, thereby killing cells that might otherwise have mutated to the androgen-independent state if allowed to continue to cycle and grow. The rationale behind Radiation Therapy Oncology Group (RTOG) P-0014 is to demonstrate in a randomized phase 3 trial that giving patients chemotherapy at the beginning of androgen blockade may improve patient survival.