Restoration of PTEN expression alters the sensitivity of prostate cancer cells to EGFR inhibitors

INTRODUCTION: Prostate cancer (CaP) progression from an androgen-dependent to an androgen-independent state is associated with overexpression of EGFR family members or activation of their downstream signaling pathways, such as PI3K-Akt and MAPK. Although there are data implicating PI3K-Akt or MAPK pathway activation with resistance to EGFR inhibitors in CaP, the potential cross-talk between these pathways in response to EGFR or MAPK inhibitors remains to be examined. METHODS: Cross-talk between PTEN and MAPK signaling and its effects on CaP cell sensitivity to EGFR or MAPK inhibitors were examined in a PTEN-null C4-2 CaP cell, pTetOn PTEN C4-2, where PTEN expression was restored conditionally. RESULTS: Expression of PTEN in C4-2 cells exposed to EGF or serum was associated with increased phospho-ERK levels compared to cells without PTEN expression. Similar hypersensitivity of MAPK signaling was observed when cells were treated with a PI3K inhibitor LY294002. This enhanced sensitivity of MAPK signaling in PTEN-expressing cells was associated with a growth stimulatory effect in response to EGF. Furthermore, EGFR inhibitors gefitinib and lapatinib abrogated hypersensitivity of MAPK signaling and cooperated with PTEN expression to inhibit cell growth in both monolayer and anchorage-independent conditions. Similar cooperative growth inhibition was observed when cells were treated with the MEK inhibitor, CI1040, in combination with PTEN expression suggesting that inhibition of MAPK signaling could mediate the cooperation of EGFR inhibitors with PTEN expression. CONCLUSIONS: Our results suggest that signaling cross-talk between the PI3K-Akt and MAPK pathways occurs in CaP cells, highlighting the potential benefit of targeting both the PI3K-Akt and MAPK pathways in CaP treatment.     

Investigations of prostate epithelial stem cells and prostate cancer stem cells

Although both prostate epithelial stem cells and prostate cancer stem cells are implicated in the differentiation of the normal prostate gland and carcinogenesis of prostate cancer, there has, until recently, been little information regarding their biology. This review summarizes the recent advancements in cell biological research including various in vitro culture systems that have offered the characterization and isolation of prostate epithelial stem cells and prostate cancer stem cells. In addition, the stromal niche or microenvironment of stem cells plays an essential role in proliferation and differentiation of normal stem cells. Stroma surrounding cancer cells, which also provide another unique niche, may involve the initiation and development of cancer stem cells. Investigation of stem cells and their microenvironments in the prostate should lead to the elucidation of biological features and the development of novel treatments for prostate cancer.     

胰岛素降解酶基因单核苷酸多态性与前列腺癌的关系研究

目的研究胰岛素降解酶(IDE)基因单核苷酸多态性与前列腺癌之间的关系。方法运用TaqMan探针SNP分析法测定192例胰腺癌患者和258例正常对照IDE基因rs4646953和rs2251101两个位点基因型,并分析IDE基因多态性与前列腺癌的关系。结果病例组IDE基因rs4646953位点TT、CT以及CC3种基因型等位基因频率分别为85.4%、14.1%和0.5%;对照组3种基因型等位基因频率分别为88.4%、10.1%和1.6%。病例组rs2251101位点TT、CT以及CC3种基因型频率分别为81.8%、16.7%和1.6%;对照组3种基因型等位基因频率分别为73.6%、23.3%和3.1%。病例组IDE基因rs4646953位点的基因型分布与正常对照组比较未见统计学差异(P=0.348),rs2251101位点病例组CT和CC基因型低于正常对照组(P=0.039)。结论 IDE基因rs2251101位点变异与前列腺癌相关。     

转单链鼠白介素12基因前列腺癌RM-1细胞的致瘤性观察

目的：探讨前列腺癌的免疫基因治疗。方法：将mIL-12基因体外转染鼠前列腺癌RM－1细胞，接种C57BL／6小鼠，观察其致瘤性。结果：转基因RM－1细胞大部分丧失致瘤性；一侧接种转AdmIL-12的RM－1细胞，引起对侧接种野生型RM－1细胞成瘤延迟、肿瘤生长减缓。结论：IL－12可诱发抗肿瘤免疫反应。     

Association of hereditary prostate cancer gene polymorphic variants with sporadic aggressive prostate carcinoma

BACKGROUND: ELAC2, MSR1, and RNASEL are candidate genes for hereditary prostate carcinoma (HPC). While, studies have demonstrated that single nucleotide polymorphisms (SNPs) in these genes are associated with sporadic disease as well as HPC, these results are often not replicated in follow-up studies. Given that the majority of patients studied had localized disease and up to 50% of localized prostate cancer is clinically insignificant, the inability to replicate the initial findings may reflect that some subjects had indolent tumors. Herein, we examine patients with metastatic disease to determine if an association exists between HPC SNPs and unambiguously significant prostate cancer. METHODS: We examined polymorphisms within ELAC2 (S217L, A541T, E622V), MSR1 (P275A, R293X, aIVS5-59c), and RNASEL (E265X, R462Q, D541E) in 150 European-Americans with metastatic prostate cancer and 170 prostate cancer-free controls using pyrosequencing assays. RESULTS: Only ELAC2 217L (37% cases vs. 29% controls (P=0.034)) and RNASEL 541E (61% cases vs. 53% controls (P=0.045)) were over-represented. Analysis of genotypes revealed that presence of the leucine ELAC2 allele (OR 1.54: 95% CI=0.99-2.41, SS vs. SL, LL) and homozygosity for the glutamic acid RNASEL allele (OR 1.68: 95% CI=1.04-2.70, EE vs. DE, DD) were associated with increased risk. Patients with both genotypes were of particularly high-risk (OR 2.66: 95% CI=1.36-5.19). CONCLUSIONS: These results suggest that, in a European-American population, ELAC2 217L and RNASEL 541E are associated with metastatic sporadic disease. ELAC2 and RNASEL SNP analysis may prove useful in determining which patients are at risk for developing clinically significant prostate carcinoma.     

Livin靶向ASODN对前列腺癌PC3细胞生物学特性的影响

目的：合成Livin靶向的反义核苷酸（ASODN）,观察其对前列腺癌PC3细胞凋亡和增殖等生物学特性的影响。方法：合成全硫代磷酸化修饰的LivinASODN并通过脂质体转染前列腺癌PC3细胞。采用MTT法检测其对细胞增殖的影响,采用RT—PCR检测转染后Livin基因mRNA的表达情况,采用流式细胞仪检测转染后细胞的凋亡效应,采用体内成瘤实验比较细胞在裸鼠体内成瘤性的变化,采用激酶法测定Caspase-3活性的变化。结果：LivinASODN转染PC3细胞后,与对照组相比,实验组细胞内LivinmRNA的表达水平下调（P〈O．01）;细胞的增殖受到显著抑制（P〈O．01）;细胞凋亡率明显增高（P〈O．01）;肿瘤细胞在荷瘤鼠体内的成瘤体积小于对照组（P〈O．05）;Caspase-3活性明显增加（P〈0．05）。结论：靶向Livin基因的ASODN干扰了前列腺癌PC3细胞中Livin基因的表达,抑制了细胞的增殖并诱导其凋亡,延缓了肿瘤细胞的生长。     

硼替佐米增强前列腺癌细胞对NK细胞介导细胞杀伤作用的敏感性

目的:探讨硼替佐米是否能够增强前列腺癌细胞对NK细胞介导杀伤作用的敏感性,以及是否在不同类型的人前列腺癌细胞系中有相似的作用。方法:以激素依赖性的前列腺癌细胞株LNCaP和激素非依赖性的前列腺癌细胞株DU145为模型,不同浓度(0、5、10、15、20、25nmol/L)硼替佐米处理细胞后,CCK-8法检测肿瘤细胞的增殖,Annexin V/PI法检测细胞凋亡率。结果:15、20、25nmol/L硼替佐米处理DU145细胞48、72h后,各处理组细胞的增殖率分别为(82.79±2.04)%、(73.59±2.95)%、(74.16±6.16)%和(71.24±5.30)%、(51.20±2.91)%、(38.02±2.67)%,同样处理LNCaP细胞后,各处理组细胞的增殖率分别为(77.04±7.74)%、(42.61±6.62)%、(23.85±6.04)%和(36.45±7.02)%、(14.94±5.76)%、(11.65±5.87)%。与对照组相比,硼替佐米强烈抑制两种细胞系的增殖(P0.05)。15、20、25nmol/L硼替佐米处理DU145细胞24h后,DU145细胞的凋亡率分别为(14.41±1.32)%、(16.13±1.55)%、(14.48±1.42)%,而在LNCaP细胞,20、25nmol/L硼替佐米处理24h后,凋亡率为(12.77±1.28)%和(14.84±1.65)%,与对照组相比有统计学差异(P0.05),DU145细胞对硼替佐米诱导的凋亡作用较LNCaP细胞更加敏感。但是,在短期分析中硼替佐米不能致敏两种细胞系对NK细胞介导的杀伤作用。在长效分析中,用硼替佐米处理肿瘤细胞后,20nmol/L硼替佐米+NK组诱导的DU145细胞和LNCaP细胞凋亡率分别为(41.83±5.06)%和(30.31±3.62)%,较单独应用硼替佐米或者NK细胞更高(P0.05)。结论:硼替佐米能够应用于致敏前列腺癌细胞对NK细胞介导的杀伤作用的敏感性,提高当前前列腺癌的治疗水平。而且此治疗策略对雄激素非依赖性的前列腺癌患者更有效。     

Smac基因诱导前列腺癌细胞凋亡的实验研究

目的：观察Smac基因对前列腺癌细胞凋亡的影响。方法：前列腺癌细胞株（PC-3）在含小牛血清的DMEM-F12培养基中培养、传代。通过脂质体介导将Smac基因导入前列腺癌细胞株,通过RT-PCR法检测SmacmRNA的表达,同时用SABC免疫组化法分析Smac的表达。采用细胞计数法检测细胞生长抑制率,流式细胞仪观察细胞凋亡情况。结果：转染Smac基因后,RT-PCR可检测出Smac的特异条带,SABC结果转染组Smae蛋白表达显著性增强,前列腺癌细胞的生长明显受抑制（P〈0．05）。细胞周期分析可见凋亡峰,凋亡率35．2％。结论：转入Smac基因可显著促进前列腺癌细胞细胞的凋亡。     

MTA1基因调控人前列腺癌PC-3细胞失巢凋亡的研究

目的:探讨MTA1基因小干扰RNA(siRNA)对前列腺癌细胞PC-3增殖和失巢凋亡的影响。方法:应用MTA1 siRNA转染处理人前列腺癌细胞系PC-3后,采用实时定量PCR和W estern印迹检测MTA1基因mRNA和蛋白水平,采用软琼脂集落培养试验检测锚着不依赖性增殖,采用琼脂糖凝胶电泳和流式细胞术检测癌细胞失巢凋亡。结果:与对照组比较,MTA1基因siRNA转染组MTA1 mRNA和蛋白水平明显下降,且呈浓度依赖性(r=0.935,P=0.0001)。MTA1 siRNA转染组软琼脂集落形成数明显减少,且与浓度相关(r=0.901,P=0.0005)。琼脂糖凝胶电泳和流式细胞术结果显示,MTA1 siRNA转染可诱导前列腺癌细胞失巢凋亡,且与浓度相关(r=0.916,P=0.0003)。结论:MTA1 siRNA可抑制人前列腺癌细胞增殖,诱导失巢凋亡是其机制之一。     

Retinoblastoma gene mutations in primary human prostate cancer

Structural alterations in the entire coding regions (exons 1 to 27) of the retinoblastoma (RB) gene in primary human prostate cancers were investigated, using polymerase chain reaction and single strand conformational polymorphism analysis of RNA. Of 25 samples obtained from patients, four (16.4%) were found to have RB alterations. DNA sequencing of the PCR products revealed point mutations resulting in single amino-acid substitutions of exons 6 and 19 in two cases, and base deletions of exons 8 and 17 in two cases. Two of four cases with RB mutations were moderately differentiated localized tumors and other two with RB mutations were poorly differentiated tumors with metastases. Our results suggest that RB gene mutation is involved in progression steps of prostate carcinogenesis. © 1995 Wiley-Liss, Inc.     

Bisphosphonate induces apoptosis and inhibits pro-osteoclastic gene expression in prostate cancer cells

AIM: Bisphosphonates are well established for the management of cancer-induced skeletal complications. Recent studies suggest that bisphosphonates promote apoptosis of cancer cells as well as osteoclasts in bone metastatic sites. To determine the direct effects of bisphosphonate on prostate cancer, we examined the effects of minodronate on prostatic cancer cell growth and the expression of apoptosis-related proteins and osteoclastogenic factors. METHODS: PC-3, DU145 and LNCaP cells were treated with amino-bisphosphonate minodronate. Then proliferation, apoptosis and expression of bcl-2, bax, poly (ADP)-ribose polymerase (PARP), caspase-3, receptor activator of nuclear factor-kappaB ligand (RANKL), osteoprotegerin (OPG), matrix metalloproteinases-2 (MMP-2), and parathyroid hormone related protein (PTHrP) were assessed. RESULTS: The proliferation of prostatic cancer cells was inhibited by minodronate. DNA fragmentation and TUNEL-positive nuclei were observed in minodronate-treated PC-3 cells. Minodronate decreased bcl-2 expression and induced bax expression, caspase-3 activity and degradation of PARP in DU145 and PC-3 cells. Minodronate decreased expression of RANKL, PTHrP and MMP-2 in PC-3 cells. CONCLUSIONS: Our results suggest that bisphosphonate not only promotes apoptosis directly but also decreases pro-osteoclastic gene expression in prostate cancer cells.     

环巴胺对人前列腺癌LNCaP细胞增殖和凋亡作用及对PCA3基因表达的影响

目的:探讨环巴胺对人前列腺癌LNCaP细胞增殖和凋亡的作用及对PCA3基因表达的影响。方法:不同浓度环巴胺(1、5、10、15μmol/L)干预LNCaP细胞,以只加入RPMI 1640培养液为空白对照组,分别在不同作用时间(24、48、72h),用MTT法检测其对细胞增殖的抑制、流式细胞术观察细胞凋亡率变化、Hoechst染色观察凋亡细胞形态变化、实时荧光定量逆转录聚合酶链反应(FQ-RT-PCR)观察对PCA3基因表达的影响。结果:5、10、15μmol/L环巴胺对LNCaP细胞增殖均有显著抑制作用,与空白对照组相比差异有显著性(P0.01),10μmol/L组于48h达到半数抑制量(IC50);10、15μmol/L组24、48、72hLNCaP细胞的凋亡率分别为37.21%、57.38%、57.98%和21.16%、71.31%、72.90%,与空白对照组相比差异均有显著性(P0.01)。随着环巴胺浓度增大和作用时间的延长,LNCaP细胞凋亡显著增加。PCA3基因的表达随着环巴胺浓度的上升呈现明显的递减趋势,较空白对照组显著降低(P0.01)。浓度为10μmol/L时,不同作用时间PCA3基因的表达均极低。结论:环巴胺浓度为10、15μmol/L作用48、72h时能够明显抑制LNCaP细胞的增殖,诱导细胞凋亡,并显著下调LNCaP细胞PCA3基因的表达。