有丝分裂激活蛋白激酶在人前列腺癌细胞中的激活

目的 探讨前列腺癌（PCa)细胞中有丝分裂激活蛋白激酶（MAPK）的激活。方法 采用免疫沉淀和Western blot方法,检测人PCa细胞株LNCaP及DU－145中磷酸化MAPK的表达及雄激素或表皮生长因子（EGF）对其表达的影响。结果 在DU－145中,磷酸化MAPK表达本底水平比LNCaP高10倍。雄激素和EGF处理后8hLNCaP中MAPK激活水平升高,24h达最高,分别比本底高约10倍和5倍,在DU－145中仅EGF可促使MAPK激活水平升高,8h开始升高,24h达最高,比本底高约10倍。结论 在雄激素非依赖性人PCa细胞增生中,MAPK激活比在雄激素依赖性人PCa细胞中作用大,MAPK激活也参与了雄激素和EGF的增生刺激作用。     

EGF信号通路对雄激素非依赖性前列腺癌细胞株DU145细胞周期的影响

目的探讨EGF信号通路影响雄激素非依赖型前列腺癌细胞系DU145细胞周期分子学机理.方法MTT法检测EGF对DU145细胞增殖能力的影响,流式细胞仪检测细胞周期,Western印迹检测细胞周期调控因子的表达情况.结果EGF组细胞增殖能力显著升高,EGF组细胞在S期细胞比例为65.36%,明显高于对照组的44.32%,两者比较差异有统计学意义(P＜0.01);在蛋白质水平,EGF降低了p27表达,而CDK2、磷酸化Rb的表达不同程度增高,p16、p21表达无明显差异.结论EGF刺激导致其下游的信号通路活化,降低p27表达,并导致下游CDK2、Rb及Rb磷酸化水平的变化,最终促进了DU145细胞的增殖能力.     

p27kip1基因逆转录病毒载体的构建及其对人胃癌细胞系生长抑制作用的研究

目的：研究逆转录病毒介导的p27^kip1基因过度表达对细胞周期和细胞增殖的影响。方法：构建含人p27^kip1基因的逆转录病毒真核表达载体，应用脂质体介导法，将外源性p27^kip1基因转染人胃癌细胞系BGC－823，应用Western blot,FCM等方法，检测p27^kip1蛋白在胃癌细胞内的表达及其对细菌胶殖的影响。结果：获得含人p27^kip1 cDNA的重组逆转录病毒载体，外源性野生型p27^kip1基因整合于胃癌细胞并获稳定表达，细胞生长速度受抑制，同时出现G1期阻滞。结论：构建的p27^kip1重组逆转录病毒能有效介导外源性p27^kip1在人胃癌细胞系中高表达，抑制细胞增殖，为进一步研究以p27^kip1为目的基因的肿瘤基因治疗奠定了基础。     

Gefitinib对前列腺癌DU145细胞EGFR、MAPK、AKt及PKC蛋白表达的影响

目的探讨在Gefitinib 作用下前列腺癌DU145细胞表皮生长因子受体(EGFR)、促分裂原活化蛋白激酶(MAPK)、丝氨酸蛋白激酶(AKt)及蛋白激酶C(PKC)蛋白表达水平的变化.方法使用终浓度为10μmol/L Gefitinib体外作用于DU145细胞,Western blot检测DU145细胞EGFR、MAPK、AKt、PKC蛋白表达水平.结果 经Gefitinib作用后DU145细胞EGFR、Akt蛋白水平分别降低了69.57%和58.31%,而MAPK及PKC 蛋白分别仅降低35.93%和32.7%.结论 Gefitinib作用后DU145细胞发生生长抑制可能和EGFR、Akt蛋白表达抑制有关,而和MAPK及PKC蛋白抑制无关.     

大鼠系膜细胞增殖时S期激酶相关蛋白2表达的变化及机制

目的：探讨系膜细胞增殖时细胞周期蛋白依赖性蛋白激酶抑制物p27^kip1的降解限速蛋白——S期激酶相关蛋白2（Skp2）表达的变化及其机制。方法：原代培养的大鼠系膜细胞同步后分为无血清组、20%胎牛血清（FCS）刺激组。MTT法检测细胞增殖;实时定量PCR和Western Blot检测p27^kip1和Skp2的mRNA、蛋白表达。结果：p27^kip1在静止期系膜细胞高丰度表达,20%FCS刺激诱导细胞增殖后p27^kip1蛋白表达显著下调;实时定量PCR研究结果显示p27^kip1的mRNA表达水平差异无统计学差异,p27^kip1蛋白和mRNA表达不一致。蛋白酶体抑制剂MG-132可显著改善系膜细胞增殖时p27^kip1蛋白水平的下降。Skp2表达在静止期系膜细胞几乎检测不出,20%FCS刺激诱导细胞增殖后Skp2表达量显著上调。结论：系膜细胞Skp2表达显著上调导致p27^kip1降解增加,可能是p27^kip1蛋白水平下降、系膜细胞增殖的重要原因,为进一步阐明疾病状态下系膜细胞增殖的机制提供了新的研究靶点。     

p38信号通路对腹膜间皮细胞p27kip1和纤连蛋白的影响

目的 探讨p38有丝分裂素激活蛋白激酶(MAPK)对高糖诱导的人腹膜问皮细胞(HPMC)p27^kip1的表达和纤连蛋白(FN)分泌的影响。方法 同步化生长融合的HPMC在有或无p38 MAPK抑制剂SB203580的条件下和不同浓度的葡萄糖共同孵育。采用Bradford法测定细胞内总蛋白量。采用逆转录．聚合酶链反应(RT．PCR)方法检测p27^kip1 mRNA的表达。p27^kip1和p38 MAPK蛋白用Western印迹法测定。采用酶联免疫吸附试验(ELISA)测定细胞培养液FN水平。结果 高糖刺激HPMC时细胞内总蛋白量、p27^kip1蛋白及细胞培养液里的FN蛋白水平明显升高。抑制p38 MAPK活性可有效阻断高糖介导的腹膜间皮细胞p27^kip1的表达及FN的分泌。结论 高糖通过p38 MAPK的活化可上调HPMC p27^kip1的表达和FN的分泌。     

突变型p27kip1过表达对胆管癌细胞增殖及凋亡的影响

目的探讨外源性突变型p27^kip1高表达，对人源性胆管癌细胞增殖及凋亡的影响。方法通过携带人突变p27^kip1基因的重组腺病毒载体Ad-p27mt和重组腺病毒Ad-LacZ，转染人胆管癌细胞系QBC9。逆转录-聚合酶链反应（RT-PCR）和Western印记，检测p27^kip1在胆管癌细胞系中mRNA和蛋白的表达水平；噻唑蓝（MIT）比色法、克隆形成试验及流式细胞术（PCM），检测p27^kip1过表达对胆管癌细胞生长抑制、细胞周期和凋亡的影响。结果Ad-p27mt能显著抑制胆管癌细胞的生长，诱导G0／G1期阻滞和细胞凋亡。结论携带人突变p27^kip1基因的重组腺病毒对QBC939细胞的增殖有明显的抑制作用，并诱导强烈的G1期阻滞和细胞凋亡，是胆管癌基因治疗的新途径。     

血清和糖皮质激素诱导的蛋白激酶1对大鼠肾动脉平滑肌细胞增殖的作用及机制

目的探讨血清和糖皮质激素诱导的蛋白激酶1（SGK1）对大鼠。肾动脉平滑肌细胞增殖的作用及其可能的分子学机制。方法组织块贴壁法原代培养的大鼠平滑肌细胞（VSMCs）,将带有SGK1显性激活型突变体质粒（pIRES2-EGFP^-S422D SGK1 mutant SD）转染VSMCs,采用细胞计数,细胞流式技术、MTT比色法分析转染后平滑肌细胞增殖及细胞周期情况,应用Western Blot方法检测SGK1对细胞周期调控蛋白p27^kip1、p21^cip1、和增殖细胞核抗原（PCNA）的作用。结果SGK1能刺激平滑肌细胞增殖,使滞于G0／G1期细胞减少,周期调控蛋白p27^kip1、p21^cip1表达下降,PCNA表达升高。结论SGK1可能通过调节PCNA,p27^kip1和p21^cip1蛋白,参与细胞周期的调控,促进平滑肌细胞增殖。     

p27kip1基因表达对大鼠移植静脉内膜平滑肌细胞增殖与凋亡的影响

目的观察以聚乳酸聚乙醇酸（PLGA）纳米粒子为载体的人p27^kip1基因局部转染自体移植静脉后，对大鼠静脉内膜平滑肌细胞增殖及凋亡的影响。方法Wistar大鼠120只建立自体静脉移植模型，随机分成3组。转基因组：移植静脉转染以PLGA纳米粒子为载体的p27^kip1基因；空白对照组：转染不含有p27^kip1基因的单纯PLGA纳米粒子；单纯静脉移植组：使用生理盐水。分别于术后3、7、14、28d取材，常规HE、Verhoeff弹力纤维染色，Western blot检测p27^kip1蛋白的表达，免疫组化（SABC）法检测增殖细胞核抗原（PCNA）的表达、TUNEL法观察内膜平滑肌细胞凋亡的动态变化。结果转基因组内膜中p27^kip1蛋白表达水平高于其他组；内膜平均厚度7、14、28d低于其他2组（P〈0．01）；转基因组内膜PCNA的表达7、14d明显受到抑制（P〈0．01），平滑肌细胞的凋亡细胞百分比于7、14d较对照组明显增加（P〈0．01），单纯静脉移植组与空白对照组之间各项监测指标差异无统计学意义。结论p27^kip1基因的过表达能够有效抑制自体静脉移植后的内膜增生（IH），促进平滑肌细胞的凋亡。     

FOXN2在前列腺癌组织的表达及对前列腺癌细胞生物学的影响

探讨双头框蛋白N2（FOXN2）在前列腺癌（PCa）组织中的表达以及对PCa细胞生物学的影响。方法 选取宜宾市第二人民医院50例接受手术治疗的PCa患者的标本及癌旁组织,通过RT-qPCR实验和Western blot实验分别检测PCa组织和癌旁组织中的FOXN2 mRNA及蛋白的表达水平,并分析PCa组织中FOXN2与患者临床病理特征的相关性。通过RT-qPCR实验检测正常前列腺细胞RWPE-1、PCa细胞PC-3、DU145、LNCaP中FOXN2 mRNA的表达水平。选取PC-3细胞为研究对象,分为FOXN2过表达组、空载体对照组以及对照组,分别通过MTT实验、流式细胞实验、Transwell实验以及Western blot实验检测各组细胞增殖、凋亡、迁移和侵袭情况以及相关蛋白Bax、CyclinD1、MMP-2的表达量。结果 与癌旁组织相比,FOXN2的mRNA和蛋白表达水平显著降低（P<0.05）,与TCGA数据库中结果一致。FOXN2低表达与PCa患者淋巴转移、TNM分期以及Gleason评分有关（P=0.003、0.005、0.002）。与人正常前列腺细胞RWPE-1相比,FOXN2在PCa细胞PC-3、DU145、LNCaP中均呈现低表达（P<0.05）,其中PC-3细胞中表达量最低。与对照组和空载体对照组相比,FOXN2过表达组的PC-3细胞在作用24 、48 、72 h后增殖能力显著下降（F=290.400、57.735、113.014,P<0.05）,CyclinD1蛋白表达水平显著下降（P<0.05）;PC-3细胞的凋亡率显著升高（P<0.05）,Bax蛋白表达水平显著升高（P<0.05）;PC-3细胞的迁移和侵袭能力显著下降（P<0.05）,MMP-2蛋白表达水平显著下降（P<0.05）。结论 FOXN2在PCa组织及细胞中低表达,过表达FOXN2可抑制PCa细胞的增殖、迁移和侵袭,并促进细胞凋亡。     

PI3K/Akt signaling regulates p27(kip1) expression via Skp2 in PC3 and DU145 prostate cancer cells, but is not a major factor in p27(kip1) regulation in LNCaP and PC346 cells

BACKGROUND: We compared the involvement of PI3K/PTEN/Akt signaling in the regulation of the cell-cycle regulator p27(kip1) and investigated the mechanism of PI3K/PTEN/Akt modulation of p27(kip1) in the prostate cancer cell lines LNCaP, PC346, PC3, and DU145. METHODS: PI3K/PTEN/Akt signaling was manipulated by wortmannin or specific siRNA. The effects on PI3K/Akt downstream effectors and p27(kip1) expression were monitored on RNA and protein levels. RESULTS: PI3K/Akt inhibition in LNCaP and PC346 cells hardly affected p27(kip1) expression. As shown in LNCaP cells, p27(kip1) expression inversely correlated with Skp2 expression, but Skp2 was not regulated by Akt. Blocking PI3K/Akt signaling in PC3 cells resulted in decreased Skp2 protein expression and increased p27(kip1). Downregulation of PTEN in DU145 cells also showed PTEN/Akt-dependent regulation of Skp2 and p27(kip1). CONCLUSIONS: In PC3 and DU145 cells, Skp2 is the main determinant in the PI3K/Akt-dependent regulation of p27(kip1). In LNCaP and PC346 cells, PI3K/Akt signaling is not a major factor in p27(kip1) regulation.     

Resveratrol induced serine phosphorylation of p53 causes apoptosis in a mutant p53 prostate cancer cell line

PURPOSE: Resveratrol (Calbiochem, La Jolla, California) is a naturally occurring stilbene reported to cause apoptosis in various cultured cancer cells. In the current study the effect of resveratrol was determined in the androgen insensitive DU 145 prostate cancer cell line. Induction of apoptosis and activation of apoptosis related signal transduction pathways were measured. MATERIALS AND METHODS: DU 145 cells were treated with resveratrol and apoptosis was measured by determining nucleosome content. Activation of mitogen activated protein kinase (MAPK) (extracellular signal-regulated kinase 1/2), p53 content and serine-15 phosphorylation of p53 were measured by immunoblot. Electrophoretic mobility shift assay of p53 binding to DNA, and measurement of p21 and glyceraldehyde-3-phosphate dehydrogenase messenger RNA were also done. RESULTS: Resveratrol induced apoptosis in DU 145 cells. The stilbene activated MAPK and caused increased abundance of p53 and serine-15 phosphorylated p53. Resveratrol induced serine-15 phosphorylation of p53 was blocked by PD 98059 (Calbiochem), a MAPK kinase inhibitor, implicating MAPK activation in the phosphorylation of p53. PD 98059 also inhibited resveratrol induced apoptosis. These results suggest that apoptosis induction by resveratrol in DU 145 cells requires serine-15 phosphorylation of p53 by MAPK. Inhibition of MAPK dependent serine-15 phosphorylation resulted in reduced p53 binding to a p53 specific oligonucleotide on electrophoretic mobility shift assay. Pifithrin-alpha (Calbiochem), a p53 inhibitor, blocked resveratrol induced serine-15 phosphorylation of p53 and p53 binding to DNA. Resveratrol caused a p53 stimulated increase in p21 messenger RNA. Transfection of additional wild-type p53 into DU 145 cells induced apoptosis, which was further enhanced by resveratrol treatment. CONCLUSIONS: Resveratrol causes apoptosis in DU 145 prostate cancer cells. This action depends on the activation of MAPK, increase in cellular p53 content, serine-15 phosphorylation of p53 and increased p53 binding to DNA.     

澳洲茄边碱对前列腺癌细胞增殖的抑制作用及机制研究

目的：研究澳洲茄边碱(solamargine,SM)对人前列腺癌激素非依赖细胞增殖的影响及可能的作用机制.方法用不同浓度 SM(0、1、2、4、6、8、10μmol/L)处理 DU145和 PC3细胞, MTT法检测 SM 对细胞生长的影响,Western blot 检测 SM 对相关信号通路蛋白 p38 MAPK、ERK1/2 MAPK、MUC1表达的影响.结果6μmol/L SM作用24 h后DU145和PC3细胞活力分别为(52.53±9.05)％、(56.28±2.36)％,并具有时间和剂量依赖;10μmol/L SM作用24 h后细胞活力分别为(27.36±2.72)％、(32.07±2.53)％.流式细胞术分析显示不同浓度 SM(0、4、6、8μmol/L)处理 PC3细胞能引起 PC3细胞阻滞在 G1期,G1期细胞比例分别为(52.61±0.50)％、(52.96±1.49)％、(66.16±2.84)％和(69.03±2.38)％.且能激活 MAPK信号通路减少下游蛋白 MUC1的表达.结论 SM能明显抑制DU145和PC3细胞生长,该作用可能与 MAPK信号通路的激活以及下游 MUC1蛋白表达下调有关.     

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.     

Inactivation of the NF2 tumor suppressor protein merlin in DU145 prostate cancer cells

BACKGROUND: The neurofibromatosis 2 (NF2) tumor suppressor gene product merlin is an important regulator of contact-dependent cell proliferation. Phosphorylation of merlin at serine 518 (Ser518) by the Rac effector p21-activated kinase (PAK) inactivates merlin's growth suppressing function, and is regulated by cell-culture conditions, including cell density, cell/substrate attachment, and growth factor availability. We examined the regulation of merlin expression and merlin phosphorylation in prostate cancer cells. METHODS: Phosphorylation of merlin in five prostate cancer cell lines (LNCaP, DU145, PC3, 22RV1, and LAPC-4) was examined by Western blotting using anti-phospho-merlin (Ser518) antibody. The activity of PAK, an upstream regulator of merlin phosphorylation, was measured by Western blotting using phospho-PAK (Ser141) antibody. The effects of various cell-culture conditions on the phosphorylation levels of merlin and PAK were analyzed. RESULTS: Both merlin expression and phosphorylation were low in LNCaP, PC3, 22RV1, and LAPC-4 prostate cancer cells. In DU145 cells, total and phosphorylated merlin were abundant, but phosphorylation was not inhibited by high cell density, serum withdrawal, the addition of hyaluronic acid or inhibition of CD44 expression, all of which are reported to inhibit merlin phosphorylation in non-neoplastic cells. PAK activation was elevated in DU145 cells and the addition of a PAK-specific inhibitor peptide but not the Rac1-specific inhibitor NSC23766 inhibited both PAK and merlin phosphorylation. CONCLUSIONS: Merlin is inactivated in DU145 prostate cancer cells by PAK-mediated constitutive phosphorylation, identifying a novel mechanism of merlin inactivation in neoplastic cells.     

Radiosensitivity of prostate cancer cells is enhanced by EGFR inhibitor C225

PurposeTo determine the direct effects of the epidermal growth factor receptor (EGFR) inhibitor C225 on the radiosensitivity of human prostate cancer cells.Experimental designHuman prostate cancer DU145 cells were irradiated with ⁶⁰Co (1.953 Gy/min) at various doses in the presence or absence of C225. The cellular proliferation and cell-survival rate were evaluated by MTT and colony-forming assays after irradiation. The cell-cycle distribution, cell apoptosis, and MAPK expression were investigated using FCM. The expression of Cyclin D1, CDK2, CDK4, and Survivin were determined by RT-PCR.ResultsThe RBE in the C225 group compared with that in the control group was 1.39. Cells treated with C225 and irradiated at 4 Gy predominantly exhibited G₀/G₁ phase arrest and significant decrease in the fraction of cells in the S phase in comparison with those in the control cells, respectively. An evidently higher apoptosis rate on irradiation at 4 Gy was observed in C225-treated cells compared with that in the control cells. Decreased cell proliferation and increased cell death were further supported by the down-regulation of cyclin D1, CDK2, CDK4, and survivin in C225-treated DU145 cells, as determined by RT-PCR. Furthermore, C225 significantly inhibited the phosphorylation of P38-MAPK in DU145 cells.ConclusionsThe EGFR inhibitor C225 increased the radiosensitivity of DU145 cells through antiproliferative effect, inhibition of clonal growth, G₀/G₁ phase arrest, apoptosis induction, and inhibition of EGFR-signaling pathways by the down-regulation of MAPK activation.     

鱼藤素诱导人前列腺癌细胞凋亡及其机制研究

目的 观察鱼藤素对于激素抵抗型前列腺癌(HRPC)细胞PC3和DU145增殖、细胞周期和凋亡的影响并探讨其机制.方法 设阴性对照组(有细胞但不加药),空白对照组(无细胞仅有培养液),阳性对照组(渥曼青霉素100 nmoL/L),及鱼藤素分别10、100、1 ìmol/L共6组.CCK-8法进行细胞毒性实验,检测细胞生长抑制率.流式细胞术检测细胞周期和凋亡,Westem-blot检测Akt、MAPK及其磷酸化蛋白表达,探讨药物作用机制.结果 10 nmol/L～1 ìmol/L鱼藤素对PC3细胞均有生长抑制作用,呈现明显的时间、浓度依赖性,对DU145细胞则无此作用.鱼藤素使PC3细胞出现G2/M期阻滞现象并引起浓度依赖性的凋亡,而未改变DU145细胞的周期分布也不能诱导其凋亡.鱼藤素能够阻断P13K/AKT通路而对MAPK通路无影响.结论 鱼藤素通过阻断PI3K/AKT通路实现抑制PC3细胞增殖、诱导凋亡的作用.两株细胞间实验结果 的差异是因为其PI3K/AKT通路活化状态的差异造成的.     

p27kip1高表达对前列腺癌PC-3细胞增殖和侵袭转移的影响

目的　探讨外源性人p2 7kip1的高表达对前列腺癌PC 3细胞增殖和侵袭能力的影响。方法　利用携带人p2 7kip1基因的腺病毒 (Ad p2 7kip1)体外转染人前列腺癌PC 3细胞 ,逆转录 聚合酶链反应 (RT PCR)、Western印迹法分别检测目的基因不同水平的表达 ,通过细胞生长试验、流式细胞仪分析技术以及Boyden小室法检测PC 3转染前后细胞增殖、细胞周期、细胞凋亡和细胞体外侵袭力的变化。以Ad X gal病毒作为对照。 结果　RT PCR、Western印迹法检测转染Ad p2 7kip1后PC 3细胞的p2 7kip1 mRNA(3 2 0bp)、p2 7蛋白 (2 7× 10 3 )表达阳性 ,转染后对PC 3细胞的生长有抑制作用 ,出现明显的G0 G1期阻滞 ,早期细胞凋亡率有所增加 ,与对照组比较差异有显著性 ,Boyden小室法检测转染后体外侵袭力受到明显抑制。结论　重组腺病毒介导的人 p2 7kip1基因在体外对前列腺癌细胞系PC 3的细胞增殖和侵袭力有明显抑制作用 ,可望作为前列腺癌基因治疗的有效工具。     

Mitogenic and anti-apoptotic actions of adipocyte-derived hormone leptin in prostate cancer cells

OBJECTIVE

To investigate the proliferative and anti‐apoptotic effects of leptin on human prostate cancer cells, and the role of related signalling pathways in mediating these actions, as obesity is a possible risk factor for prostate cancer and leptin, an adipocyte‐derived hormone, has mitogenic action in various cell types.

MATERIALS AND METHODS

Two human prostate cancer cell lines, DU145 and PC‐3, were treated with leptin (5–100 ng/mL) for up to 48 h. Under serum‐free conditions, cell proliferation was measured using a colorimetric tetrazolium assay and apoptosis by an enzyme‐linked immunosorbent assay measuring cell death. Also, the phosphorylation of ERK1/2 and Akt was detected by Western blotting, and specific inhibitors of mitogen‐activated protein kinase (MAPK) (PD98059; 40 µm ) and phosphatidylinositol 3‐kinase (PI3‐K, LY294002; 40 µm ) were used to evaluate the role of these signalling pathways.

RESULTS

Leptin dose‐dependently increased the cell number in both cell lines for up to 48 h of incubation, the mean (sem ) percentage of the control being 189 (4.3)% for DU145 and 173 (7.5)% for PC‐3 (100 ng/mL leptin, 48 h; P < 0.01). Leptin also significantly reduced the number of apoptotic cells after 24 h of treatment, dose‐dependently caused ERK1/2 and Akt phosphorylation; pretreatment with inhibitors of MAPK and PI3‐K inhibited these responses.

CONCLUSION

These results show that chronic increases in leptin might enhance the growth of prostate cancer via the MAPK and PI3‐K pathways. Further studies are needed to investigate whether the ability of leptin to stimulate mitogenic/anti‐apoptotic signal transduction pathways could represent a target for anticancer drug discovery.