Synthetic retinoid CD437 induces S-phase arrest and apoptosis in human prostate cancer cells LNCaP and PC-3

BACKGROUND: Exposure of prostate carcinoma cell lines to retinoids, which function through the classical retinoic acid nuclear receptor, (RARs) or retinoid X receptors (RXRs), results in minimal cytostatic inhibition of cell proliferation. METHODS: Growth inhibition and various regulatory responses were investigated in two human prostate carcinoma cell lines (LNCaP and PC-3) treated with or without a synthetic retinoid, CD 437. RESULTS: Incubation of prostate carcinoma cell lines with a novel retinoid CD437 resulted in the marked inhibition of proliferation. LNCaP and PC-3 possessed IC50 values for CD437 of 375 nM and 550 nM, respectively. Incubation with 1 microM CD437 for 24 hr resulted in 100% and 60% inhibition of growth in LNCaP and PC-3 cells, respectively. Simultaneously, cell flow cytometric analyses revealed a dramatic increase of the cell population in S phase, in both LNCaP (from 38.6% up to 86.7%) and PC-3 (27.9% to 55.7%), and a decreased proportion of cells in G2 phase, in LNCaP (from 23.7% down to 1.2%) and PC-3 (14.9% to 2.2%), indicating a significant S-phase arrest. The cell growth inhibition and S-phase arrest in these cells were followed by apoptosis, as revealed by the acquisition of the characteristic cell morphology including the appearance of apoptotic bodies, and further confirmed by cellular DNA fragmentation. CD437-induced-S phase arrest was associated with upregulated mRNA levels of p21waf1/cip1/sdi1 in both LNCaP (p53+/+) and PC-3 (53-/-) cells. CONCLUSIONS: CD437 represents a unique retinoid that induces S-phase arrest and apoptosis in both androgen-dependent (LNCaP) and -independent (PC-3) human prostate cancer cells, suggesting a potential role of CD437 in the treatment of human prostate cancer.     

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.     

复方中药紫龙金对前列腺癌的体外作用

目的　探讨复方中药紫龙金对前列腺癌的体外作用机理。　方法　应用MTT法、软琼脂集落生长实验、流式细胞术和显微荧光术测定紫龙金对LNCaP、DU 1 4 5和PC 3细胞的增殖抑制、集落生长抑制、周期阻滞和诱导凋亡作用 ;应用RT PCR方法检测对前列腺特异性抗原基因PSA和雄激素受体基因AR、凋亡相关基因Bcl 2和Bax以及抑癌基因p1 6表达的影响。　结果　紫龙金对 3种前列腺癌细胞系均具有剂量依赖性增殖抑制和G0 /G1 期阻滞作用 ,作用 72h时 3种细胞IC50 分别为 0 .79、0 .4 2和 0 .5 2mg/ml;对LNCaP和DU 1 4 5细胞具有诱导凋亡作用 ,可以显著抑制DU 1 4 5细胞的集落生长 ;紫龙金可以下调LNCaP细胞PSA、AR和Bcl 2表达 ,下调DU 1 4 5细胞Bcl 2 ,上调Bax和P1 6基因表达。　结论　紫龙金可以通过抑制前列腺癌细胞增殖、抑制集落生长、G0 /G1 期阻滞、诱导凋亡、调节PSA、AR、Bcl 2、Bax和p1 6基因表达等作用机理发挥抗肿瘤作用     

1alpha,25-dihydroxyvitamin D3 induced growth inhibition of PC-3 prostate cancer cells requires an active transforming growth factor beta signaling pathway

BACKGROUND: Prostate cancer growth inhibition by 1alpha,25-dihydroxyvitamin D3 (1,25(OH)2D3) is best characterized in the androgen dependent LNCaP cell line, where treatment with this hormone causes cell cycle arrest and apoptosis. 1,25(OH)2D3 also inhibits the growth of PC-3 prostate cancer cells, but not through the induction of G1 arrest or apoptosis. In this study, we have sought to elucidate the mechanism/s involved in PC-3 cell growth inhibition by 1,25(OH)2D3. EXPERIMENTAL METHODS: We determined the effect of transforming growth factor beta (TGFbeta) blocking antibodies on 1,25(OH)2D3 mediated growth inhibition of PC-3 cells. In addition, we also studied the effects of 1,25(OH)2D3 on TGFbeta signaling and receptor expression. Finally, we assessed the role of TGFbeta signaling in the induction of the growth inhibitory protein, insulin like growth factor binding protein 3 (IGFBP-3), by 1,25(OH)2D3. RESULTS: We find that 1,25(OH)2D3 action in PC-3 cells is mediated through at least two distinct pathways, the TGFbeta pathway and the IGFBP-3 pathway. We show that 1,25(OH)2D3 treatment elevates TGFbeta production and signaling, as well as receptor levels, in PC-3 cells. Further, using a blocking antibody against TGFbeta substantially reduces 1,25(OH)2D3 mediated growth inhibition without affecting IGFBP-3 induction, suggesting that IGFBP-3, alone, is insufficient to inhibit the growth of PC-3 cells.     

The role of survivin and Bcl-2 in zinc-induced apoptosis in prostate cancer cells

ObjectivesTo study the effects of zinc treatment on the gene expression levels of survivin and Bcl-2 in prostate cancer cells.Materials and methodsThe effects of zinc exposure on apoptosis were assessed using two human prostate cancer cell lines, LNCaP and PC-3. Zinc-induced apoptosis was measured by Annexin V staining. The direct effect of zinc on the expression levels of zinc transporters (ZnT-1 and ZnT-4) and apoptosis-related genes (Bax, Bcl-2, and survivin) was determined by RT-PCR analysis.ResultsWhen LNCaP and PC-3 cells were exposed to various concentrations of zinc sulfate for 48 hors, their growth was inhibited in a dose-dependent manner. The levels of zinc in both cell lines treated with zinc sulfate for 24 hours were higher than in untreated cells. Exposure to zinc induced apoptosis and necrosis in LNCaP and PC-3 cells. Apoptosis became more extensive as the treatment time with zinc increased. There was a significant increase in the gene expression levels of ZnT-1 and ZnT-4 in both cell lines treated with zinc sulfate compared with untreated cells. The expression of Bax mRNA was up-regulated, while the expression of Bcl-2 and survivin were decreased in both cell lines following zinc treatment.ConclusionsExposure to zinc sulfate in human prostate cancer cells increased intracellular levels of zinc, which resulted in increased apoptosis. The apoptogenic effect of elevated concentration of zinc could be due either to increased expression of zinc transporters and increased levels of Bax or decreased Bcl-2 and survivin expression.     

C16 ceramide accumulates following androgen ablation in LNCaP prostate cancer cells

BACKGROUND: Adenocarcinoma of the prostate is the most frequently diagnosed non-cutaneous cancer and the second leading cause of cancer-related deaths among men in the United States. The most successful therapies to date for this tumor have involved some form of androgen ablation. However, these therapies become ineffective as the tumor evolves to an androgen-insensitive state. Ceramide is a lipid second messenger that has been shown to mediate growth arrest or cell death when added exogenously to prostate cancer cells. As a first step toward understanding the events that lead to the transition of prostate cancer cells to an androgen-independent state, we considered investigating the effect of androgen ablation on endogenous ceramide levels in androgen-sensitive and androgen-insensitive prostate cancer cells. METHODS: To investigate the mechanisms of growth arrest/apoptosis in androgen-sensitive (LNCaP) and insensitive (DU-145, PC-3) cells, we used various methods including nonyl acridine orange (NAO) staining, propidium iodide (PI) staining/cell-cycle analysis, lipid analysis, and Western blotting assays. RESULTS: In this study, we demonstrate that androgen ablation drives G(0)/G(1)-phase cell-cycle arrest followed by progressive apoptosis in vitro, in LNCaP cells. Lipid analysis indicated an increase in C16 ceramide, which was generated via the de novo pathway as revealed by blockade of ceramide synthase by fumonisin B1. The addition of 5alpha-dihydrotestosterone (DHT) or fumonisin B1 rescued LNCaP cells from apoptosis induced by androgen ablation, and decreased levels of intracellular C16 ceramide. Neither apoptosis nor an increase in C16 ceramide was observed in androgen-independent cell lines following androgen ablation.     

Induction of cell cycle arrest and apoptosis in human prostate carcinoma cells by a recombinant adenovirus expressing p27(Kip1)

BACKGROUND: Adp27(Kip1), a recombinant adenovirus, was evaluated for expression of p27, a cyclin-dependent kinase inhibitor (CDKI) and tumor suppressor protein, in human prostate carcinoma cells. Effects of p27(Kip1) on cell cycle and apoptosis were analyzed. METHODS: We evaluated the effects of overexpression of p27(Kip1) in the human prostate carcinoma cell lines LNCaP, DU-145, and PC-3 in vitro and in vivo. Growth curve studies, cell cycle analysis, terminal deoxynucleotidyl transferase-mediated nick end-labeling (TUNEL), and annexin V-fluorescein isothiocyanate apoptosis analyses were conducted to determine effects of p27(Kip1) on cell cycle. CDKI activity assays and Western blots were conducted to determine presence/activities of CDKIs. RESULTS: Adp27(Kip1)-induced protein levels increased in a dose-dependent manner; p27(Kip1) protein was detected within 6 hr of infection with Adp27(Kip1) and remained stable for at least 48 hr. The activities of Cdk2, Cdk4, and Cdc2 kinases were inhibited 24 hr after infection with Adp27(Kip1). Bromodeoxyuridine incorporation demonstrated a dose-dependent decrease in S-phase cells 24 hr postinfection. TUNEL analysis revealed an induction of apoptosis (10 pfu/cell) within 48 hr of infection in all cell lines. Growth curve analyses demonstrated that Adp27(Kip1) infection inhibited proliferation of all cell lines tested and decreased cell numbers for Adp27(Kip1)-infected LNCaP and PC-3 cells by 96 hr. Cell cycle analysis of DNA content demonstrated an accumulation of cells in G0/G1-phase 24-120 hr after Adp27(Kip1)-infection. In vivo studies demonstrated a reduction in LNCaP xenograft tumor growth rates in mice injected with Adp27(Kip1). CONCLUSION: Exogenous p27(Kip1) overexpression results in cell cycle regulation in the human prostate carcinoma cell lines tested, representing the first use of this vector on prostate cancer cell lines in vitro and in vivo. Moreover, p27(Kip1) expression is associated with an increase in early apoptosis, which represents a recently discovered function for this protein. It also represents the first time this association has been observed in prostate carcinoma cell lines. This study provides support for the further development of Adp27(Kip1) as a potential therapeutic vector in the treatment of adenocarcinoma of the prostate.     

Growth inhibition of androgen-insensitive human prostate carcinoma cells by a 19-norsteroid derivative agent,mifepristone

Mifepristone, also known as RU 486, is a 19-norsteroid derivative. Currently, mifepristone is being tested in clinical trials on meningioma and breast cancer. In this study we analyzed whether mifepristone could inhibit the growth of human prostate cancer cells including androgen-insensitive (PC-3 and DU145) and androgen-sensitive (LNCaP) cell lines. At 1-nM concentration, mifepristone exhibited a marginal stimulatory action on LNCaP and PC-3 cells. Nevertheless, a dose-dependent growth inhibition on those same cell lines was observed at concentrations of 1 μM and 10 μM. Twenty-day exposure to the clinically achievable concentration of 1 μM mifepristone resulted in consistent inhibition of all three cell lines studied. Furthermore, this in vitro growth inhibition was reflected in an in vivo nude mouse system. Mifepristone at the dosage of 4 mg/100 g body weight completely suppressed the growth of PC-3 tumors for 21 days, although this was followed by a growth rate similar to that of the control tumor. To understand the possible mechanism of mifepristone inhibition, PC-3 cells were exposed to mifepristone in comparison with dexamethasone (Dex), progesterone, and 5 alpha-dihydrotestosterone (DHT), each at 1-μM concentration. The results demonstrated that while both DHT and Dex alone had essentially no effect on cell growth, progesterone alone resulted in a 20% growth inhibition, while mifepristone had more than 60% inhibition with a 16-day exposure. At an equal concentration, the degree of growth inhibition of PC-3 cells by mifepristone or progesterone was partially diminished by simultaneous exposure to Dex. In conclusion, our results demonstrated that the growth of androgen-insensitive prostate cancer cells can be directly inhibited by mifepristone in cultures. This in vitro inhibition is reflected in xenografted tumors.     

姜黄素对雄激素依赖性前列腺癌细胞的诱导凋亡作用

目的:探讨姜黄素对雄激素依赖性前列腺癌细胞株(LNCaP)的诱导凋亡作用。方法:分别用10、25、50、75、100μmol/L浓度的姜黄素作用于LNCaP细胞,5、12、24 h后MTT法检测细胞生长活性;24 h后流式细胞仪测定细胞周期及细胞凋亡的变化,透射电镜观察细胞超微结构变化;5 h后W estern印迹法检测细胞内IκBα的表达。结果:姜黄素能显著抑制LNCaP细胞的生长,呈剂量与时间依赖性,不同浓度姜黄素组之间与不同作用时间组之间的差异均有显著性意义(P均<0.05)。姜黄素诱导LNCaP细胞出现剂量依赖性G2/M期阻滞(P<0.01),各浓度组凋亡细胞比例均显著高于空白对照组(P均<0.05),差异有显著性意义;姜黄素作用24 h后LNCaP细胞出现凋亡的形态学改变;不同浓度姜黄素作用后,LNCaP细胞内IκBα的表达无变化。结论:姜黄素能显著抑制LNCaP细胞的体外生长,并促进其凋亡。     

Mechanisms involved in resveratrol-induced apoptosis and cell cycle arrest in prostate cancer-derived cell lines

Resveratrol is a polyphenol found at high concentrations in grapes and red wine with reported anticarcinogenic effects. We studied the molecular mechanism of resveratrol-induced apoptosis and proliferation arrest in prostate derived cells PZ-HPV-7 (nontumorigenic line), LNCaP (androgen-sensitive cancer line), and PC-3 (androgen-insensitive cancer line). Apoptosis and cell cycle distribution were evaluated by flow cytometry and proliferation by MTT assay and direct cell counting. Caspases, bax, bcl-2, cyclins, Cdks, p53, p21, and p27 were measured by Western blot and kinase activities of cyclin/Cdk complexes by immunoprecipitation followed by kinase assays with appropriate substrates. Resveratrol induced a decrease in proliferation rates and an increase in apoptosis in cancer cell lines in a dose- and time-dependent manner. These effects were coincident with cell accumulation at the G0/G1 phase. In LNCaP and PC-3, the apoptosis induced by resveratrol was mediated by activation of caspases 9 and 3 and a change in the ratio of bax/bcl-2. Expressions of cyclin D1, E, and Cdk4 as well as cyclin D1/Cdk4 kinase activity were reduced by resveratrol only in LNCaP cells. In contrast, cyclin B and Cdk1 expression and cyclin B/Cdk1 kinase activity were decreased in both cell lines in the presence of resveratrol. However, modulator proteins p53, p21, and p27 were increased by resveratrol only in LNCaP cells. These effects probably result in the observed proliferation arrest and disruption of cell cycle control. In addition, the specific differences found between LNCaP and PC-3 suggest that resveratrol acts through different mechanisms upon the androgen or estrogen receptor cell status.     

HSP 70反义寡核苷酸逆转LNCaP和PC-3m细胞耐药性的研究

目的：探讨热休克蛋白（HSP70）反义寡核苷酸逆转入前列腺LNCaP及PC－3m耐药性的作用。方法用MTT法和成集落试验测定了10μmol/L,HSP70反义寡核苷酸作用后不同浓度阿霉素、丝裂霉素C对LNCaP和PC－3m生长抑制率的影响。结果10μmol/LHSP70反义寡核苷酸可以显著增加4－12μg/ml阿霉素和10－100μg/ml丝裂霉素－C对PC－3m的生长抑制率以及0．01－0．08μg/ml阿霉素和1－6μg/ml丝裂霉素C对LNCaP的生长抑制率,差别有显著性意义（P＜0．05）。抑制率均超过505。结论HPS70与前列腺癌细胞的耐药性有关;HSP70反意义（P＜0．05）。报制率均超过505。结论HSP70与前列腺部细胞的耐药性有关;HSP70反义寡核苷酸可以特异性地逆转二种不同生物学特性的前列腺癌细胞的耐药性。为临床前列腺癌化疗提供了新方法。     

Effect of permixon on human prostate cell growth: lack of apoptotic action

BACKGROUND: Permixon, a phytotherapeutic agent derived from the saw palmetto or Serenoa repens plant, is a lipid/sterol extract that is believed to interfere with 5alpha-reductase activity, thus inhibiting prostate growth. In this study, we investigated the magnitude and specificity of the effect of Permixon on cell proliferation and apoptosis in human prostate cancer cells. METHODS: The effect of Permixon was examined in androgen-independent PC-3 prostate cancer cells, androgen-sensitive LNCaP prostate cancer cells, and MCF-7 breast cancer cells in vitro. Cell growth, apoptosis induction, and cell proliferation was studied after exposure to Permixon at two concentrations (10 and 100 microg/ml). Cell proliferation and cell cycle progression were determined after 24 hr on the basis of (3)[H]-thymidine incorporation assay and flowcytometric analysis, respectively. Apoptosis induction was evaluated in treated and untreated cultures using the Hoescht staining and caspase-3 activation. RESULTS: Exposure of prostate and breast cancer cells to a high dose of Permixon (100 microg/ml) resulted in a significant decrease in the rate of cell growth; an effect that was not time-dependent and was not associated with cell cycle arrest. Permixon treatment (at either high or low dose) had no effect on apoptosis induction in prostate cancer cell lines (P > 0.6). Furthermore, in vitro Permixon was a weak inhibitor of 5alpha-reductase activity type 2 in prostatic homogenates. CONCLUSIONS: The results indicate the ability of Permixon to affect prostate cancer cell growth without inducing apoptosis or cell cycle arrest. This effect was not prostate-specific and was only manifested at high concentrations of Permixon. Furthermore our findings indicate that Permixon is weak inhibitor of 5alpha-reductase compared to finasteride. This study challenges previous evidence on the anti-growth effect of Permixon in the prostate and its ability to inhibit 5alpha-reductase activity, while questioning apoptosis as a mechanism of action of this phytotherapeutic against prostate growth, a concept that may have therapeutic significance.     

STAT3 mediates IL-6-induced neuroendocrine differentiation in prostate cancer cells

BACKGROUND: In the human prostate cancer cell line LNCaP, interleukin (IL)-6 has been shown to regulate both growth and neuroendocrine (NE) differentiation. We recently observed that IL-6 mediated growth arrest in LNCaP by activating STAT 3. Since differentiation and growth arrest are often associated processes, we investigated whether STAT3 also mediated NE differentiation in this prostate cancer cell line. METHODS: We treated previously characterized clones LNCaP-neo (neomycin-resistant LNCaP) and LNCaP-SF (LNCaP-STAT3 dominant negative mutant) with IL-6 and screened for NE differentiation by observing morphological changes and immunoblotting for two NE markers, neuron-specific enolase (NSE) and chromogranin A (ChA). To characterize further the role of STAT3 in growth arrest and differentiation, we transfected a wild-type STAT3 vector into PC-3 cells and generated a subclone PC-3-S3. In this clone, we assessed differentiation by observing morphological changes and determined growth responses by cell counting and clonogenic assays. RESULTS: We observed that IL-6 induced formation of neurite extensions, morphologic features associated with NE differentiation, and enhanced expression of neuronal markers ChA and NSE in LNCaP-neo cells. In contrast, LNCaP-SF, possessing a dominant negative mutant form of STAT3, exhibited no characteristics of IL-6 induced NE differentiation. Furthermore, expression of a constitutively phosphorylated wild-type STAT3 in PC-3 cells inhibited growth and induced the formation of neurite extensions and NSE expression. CONCLUSIONS: These results indicate that STAT3 is a mediator of both NE differentiation and growth inhibition in LNCaP and PC-3, suggesting a connection between growth inhibition and NE differentiation in prostate cancer.     

人工合成小分子RNA对前列腺癌细胞周期及增殖的影响

目的 研究人工合成的dsP21-555对前列腺癌细胞株PC-3和LNCaP细胞周期和增殖的影响。方法 合成dsP21-555（实验组）和dsControl（阴性对照组）,分别转染至PC-3和LNCaP。使用Real-time PCR及Western blotting分别检测分析前列腺癌细胞转染后的p21mRNA及p21蛋白的表达情况。流式细胞术检测细胞周期分布,使用MTT实验及集落形成实验检测细胞的活力及增殖能力。结果 转染dsP21-555后PC-3和LNCaP细胞中的p21 mRNA水平分别上调至2.90倍(P<0.01)和2.05倍(P<0.01)。Western blotting实验结果符合这一趋势。流式细胞术检测显示,转染dsP21-555后,在S期和G2/M期的细胞比例下降,在G0/G1期的细胞比例则增加。MTT实验显示,与dsControl组相比,转染dsP21-555后,PC-3和LNCaP细胞的活力明显降低。集落形成实验显示,dsP21-555组的集落的数量较少,细胞增殖能力降低。结论 人工合成的dsP21-555能明显激活前列腺癌细胞中p21基因的表达,并显著抑制前列腺癌细胞周期的进展和增殖。     

苏拉明对前列腺癌PC-3M细胞生长的影响

目的 :观察苏拉明对激素非依赖性前列腺癌 (HRPC)PC 3M细胞生长、细胞周期和凋亡的影响 ,初步探讨其作用机制。　方法 :锥虫蓝活细胞拒染法和四甲基偶氮唑盐 (MTT)比色法检测不同浓度小牛血清 (2 %、5 %、1 0 % )、不同浓度的苏拉明 (1 0、50、1 0 0、2 0 0 μmol/L)对PC 3M细胞增殖的影响 ;流式细胞术 (FCM )测定苏拉明对PC 3M细胞增殖周期分布和凋亡的影响。　结果 :高浓度 (2 0 0 μmol/L)苏拉明可杀伤PC 3M细胞 ,低浓度 (1 0、50、1 0 0μmol/L)条件下则主要发挥生长抑制作用。高浓度 (1 0 % )小牛血清存在时苏拉明仍可发挥抑制和杀伤作用 ,但较低浓度 (5 %、2 % )小牛血清时弱。苏拉明可使PC 3M细胞发生细胞周期G0 /G1 期阻滞 ,并在 2 0 0 μmol/L浓度时诱导细胞凋亡。　结论 :苏拉明较为明显地抑制PC 3M细胞生长 ,并在高浓度时杀伤癌细胞 ;除抑制或阻断细胞因子和生长因子调控的增殖作用外 ,可能参与阻滞细胞周期分布和诱导细胞凋亡     

姜黄素对前列腺癌细胞核转录因子抑制蛋白表达的影响

目的观察姜黄素对前列腺癌细胞核转录因子抑制蛋白(IkBα)表达的影响,探讨姜黄素抑制前列腺癌细胞增殖的作用机制。方法分别用10、25、50、75和100μmol/L 浓度的姜黄素对雄激素依赖性及雄激素非依赖性前列腺癌细胞株 LNCaP 和 PC3进行干预,5、12和24 h 后采用噻唑蓝(MTT)比色法观察细胞增殖情况;采用流式细胞术测定24 h 后细胞周期变化;5 h 后 Western 印迹法检测细胞中 IkBα的表达。结果姜黄素显著抑制 LNCaP 及 PC3细胞的生长,呈剂量和时间依赖性;姜黄素将两种前列腺癌细胞阻滞于 G_2、M 期[LNCaP 与 PC3细胞,空白对照分别为(11.4±1.3)%与(17.3±1.7)%,100μmol/L 姜黄素作用后分别为(27.3±2.8)%与(33.4±4.0)%],从而诱导肿瘤细胞凋亡;姜黄素作用于 LNCaP 细胞后,细胞中 IkBα表达无变化(F=0.129,P>0.05);但作用于 PC3细胞后,细胞中 IkBα的表达明显增强,呈现出显著的剂量依赖性(F=31.618,P<0.05)。结论姜黄素通过活化 IkBα在 PC3细胞中的表达发挥抑制 PC3细胞增殖的作用。对于 LNCaP 细胞,姜黄素可能通过抗氧化、抑制细胞内代谢产物形成等方式抑制 LNCaP 细胞增殖。     

Stable expression of full length human androgen receptor in PC-3 prostate cancer cells enhances sensitivity to retinoic acid but not to 1alpha,25-dihydroxyvitamin D3

BACKGROUND: PC-3 prostate cancer cell growth is inhibited by 1alpha,25-dihydroxyvitamin D(3) (1,25 D) and retinoids, but not to the same extent as the androgen receptor (AR) positive LNCaP prostate cancer cells. Previous reports suggest a role for AR in growth inhibition of LNCaP cells by 1,25 D and retinoids. PC-3 cells do not express AR. We therefore asked whether re-expression of AR would enhance the response of PC-3 cells to 1,25 D and retinoids. METHODS: PC-3 cells were stably transfected with wild type human AR cDNA. Pooled cells expressing AR protein at levels comparable to LNCaP cells were used to analyze response to 1,25 D, retinoids, androgens, and anti-androgens. RESULTS: AR re-expression in PC-3 cells restored response to androgens and anti-androgens, but growth inhibition by 1,25 D was not significantly altered. However, cells were sensitized to low levels of retinoids, and, in contrast to the parental PC-3 cells, sub-optimal levels of 1,25 D and retinoids caused additive growth inhibition. CONCLUSIONS: Restoring AR expression and activity in PC-3 cells results in enhanced sensitivity to low levels of retinoids while the response to 1,25 D remains unaltered. Thus, the involvement of AR in prostate cancer growth inhibition by 1,25 D appears to be cell line specific.     

紫杉醇和吉西他滨对前列腺癌PC-3细胞的作用

目的 :观察紫杉醇协同吉西他滨对前列腺癌细胞系PC 3的体外作用 ,并探讨其可能的作用机制。　方法 :应用光镜形态学、噻唑蓝 (MTT)法、流式细胞仪和免疫细胞化学法观察 10 -6、10 -7、10 -8mol/L浓度紫杉醇和 10 -7、10 -8、10 -9mol/L浓度吉西他滨在体外单独或协同用药对前列腺癌细胞系PC 3的作用 ,对细胞DNA含量及CyclinD1表达的影响。　结果 :10 -8mol/L以上浓度吉西他滨作用 4 8h ,可增强 10 -7mol/L以上浓度紫杉醇对前列腺癌PC 3细胞系的生长抑制 [抑制率≥ (5 0 .8± 4 .2 ) % ,P <0 .0 5 ]及诱导凋亡作用 [凋亡率≥ (2 2 .9± 2 .3) % ,P <0 .0 5 ],下调CyclinD1的表达 [表达率≤ (9.6± 1.6 ) % ],与阳性对照组CyclinD1表达率 (2 5 .5± 4 .1) %相比差异有显著性 (P<0 .0 1)。吉西他滨使紫杉醇所致的G2 /M期细胞周期阻滞比例由 (70 .3± 9.7) %变为 (38.2± 4 .2 ) % ,部分地逆转了其G2 /M期细胞周期阻滞 (P <0 .0 1)。　结论 :紫杉醇和吉西他滨可以协同增强对前列腺癌细胞系PC 3的生长抑制和诱导凋亡作用 ,显示了紫杉醇和吉西他滨协同用于治疗激素非依赖性前列腺癌的可能性 ,并部分地说明了其作用机制。     

Downregulation of androgen receptor expression by luteolin causes inhibition of cell proliferation and induction of apoptosis in human prostate cancer cells and xenografts

BACKGROUND: Androgen receptor (ARs) play a crucial role in the development and progression of prostate cancer. Recent studies have suggested that prostate cancer cell proliferation is inhibited by AR downregulation. Our aim was to investigate how luteolin, a natural flavonoid, affects cell growth and AR expression in prostate cancer cells and xenografts. METHODS: We assessed prostate cancer cell (LNCaP, DU145, and PC-3) proliferation and apoptosis by MTT assay, flow cytometric analysis, and Western analysis. AR function was measured by evaluating the AR target molecule, prostate-specific antigen (PSA), by RT-PCR, Western blotting, and enzyme-linked immunosorbent assay. We determined the mechanism of AR downregulation with cycloheximide chase assays, proteasome inhibitor, and coimmunoprecipitation experiments. The effects of luteolin on growth inhibition in vivo were examined by LNCaP xenografts in SCID mice. RESULTS: Luteolin significantly repressed prostate cancer cell proliferation and induced apoptosis in LNCaP cells. PC-3 and DU145 cells were less susceptible to luteolin-mediated growth inhibition. Luteolin simultaneously suppressed intracellular and secreted PSA levels and repressed AR mRNA and protein expression in a dose- and time-dependent manner. Luteolin reduced the association between AR and heat-shock protein 90, causing AR degradation through a proteasome-mediated pathway in a ligand-independent manner. Luteolin also suppressed LNCaP xenograft tumor growth in SCID mice. CONCLUSION: Luteolin-mediated AR downregulation contributes to the inhibition of cell proliferation and the induction of apoptosis in LNCaP human prostate cancer cells, suggesting that AR is a molecular target for luteolin-mediated anticancer activity. Luteolin may act as a chemopreventive or chemotherapeutic agent for prostate cancer.     

雷帕霉素抑制人前列腺癌细胞增殖及其作用机制

目的 观察雷帕霉素(Rapamycin)对体外培养的人前列腺癌PC-3M-2B4细胞增殖及凋亡的影响,探讨其机制.方法 分别用不同浓度的雷帕霉素(100、200、400、800μg/L)对细胞进行干预后,采用噻唑蓝(MTT)比色法检测细胞增殖变化,流式细胞术检测细胞凋亡变化,Western blot 法检测凋亡相关蛋白bcl-2及bax表达的变化.结果 雷帕霉素能明显抑制PC-3M-2B4细胞的增殖活性,此作用呈现量-效、时-效关系.雷帕霉素呈浓度依赖性诱导细胞凋亡.雷帕霉素作用PC-3M-2B4细胞后,细胞内凋亡抑制蛋白bcl-2的表达明显降低,bax蛋白的表达明显增加.结论 雷帕霉素能够通过调节凋亡相关蛋白bcl-2和bax的表达比例,诱导前列腺癌细胞凋亡,从而抑制肿瘤生长.

Abstract：

Objective To investigate the effects of Rapamycin on the growth and apoptosis of human prostate carcinoma cell line PC-3M-2B4. Methods The inhibitory effect of Rapamycin was observed at 100,200,400,800μg/L on the growth of human prostate carcinoma cell line PC-3M-2B4 in serum-free medium for different concentrations by methyl thiazol tetrazolium (MTF) assays. Flow cytometry (FCM)analysis was used to study the changes of cell apoptosis. The expression level of bcl-2 and bax was determined by Western blotting. Results Rapamycin caused dose-dependent inhibition on the growth of human prostate carcinoma cell line PC-3M-2B4 in a concentration-and time dependent manner. Rapamycin induced the apoptosis of PC-3M-2B4 cells in a concentration-dependent manner. The levels of bcl-2 protein were reduced gradually with the increase of concentration or action time. Conclusion Rapamycin, a mTOR inhibitor, inhibits the growth of human prostate cancer cell and induces apoptosis of human prostate cancer cell. mTOR might be a potential target for anti-prostate cancer.