重组天花粉蛋白高表达对人宫颈癌Caski细胞p73基因甲基化影响的机制研究

目的 探索重组天花粉蛋白(recombinant trichosanthin,rTCS)高表达对人宫颈癌Caski细胞p73基因甲基化影响的机制.方法 RT-PCR、QT-PCR、Western blot检测rTCS高表达后Caski细胞中DNA甲基化转移酶I(DNMT1)的表达变化,甲基化特异性PCR(MSP)法检测p73基因5′端启动子区CpG岛甲基化状态的改变.结果 宫颈癌Caski细胞p73为低表达,其启动子呈部分甲基化状态.高表达rTCS的细胞株其DNMT1mRNA及蛋白水平的表达均降低,其中mRNA水平降低0.56倍(P<0.01),p73基因启动子甲基化程度亦有所降低,p73mRNA水平表达升高.结论 高表达rTCS可能通过抑制DNMT1的表达,致使抑癌基因p73启动子去甲基化而重新表达,最终发挥抑癌基因功能抑制宫颈癌Caski细胞增殖.     

OPCML、DAPK基因甲基化与宫颈癌CasKi细胞凋亡相关性的研究

目的研究天花粉蛋白(TCS)诱导宫颈癌CasKi细胞凋亡过程中肿瘤抑制基因OPCML、DAPK甲基化的变化情况,并探讨其在宫颈癌的发生发展中的作用及细胞凋亡和抑癌基因甲基化的相关性,寻找新型的去甲基化药物。方法①应用MTT法检测TCS对CasKi细胞增殖抑制的影响;流式细胞仪分析天花粉蛋白对宫颈癌CasKi细胞诱导凋亡作用;②应用甲基化特异性PCR(MSP)技术检测人宫颈癌细胞OPCML和DAPK基因启动子CpG岛甲基化的状况及天花粉蛋白的去甲基化作用。结果TCS对宫颈癌CasKi细胞生长有明显抑制作用,流式细胞仪检测见特征性的亚二倍体凋亡峰;MSP检测表明宫颈癌CasKi细胞OPCML、DAPK基因启动子区CpG岛呈高度的甲基化状态,TCS处理后OPCML、DAPK基因启动子区CpG岛无异常甲基化表现。结论天花粉蛋白具有抑制宫颈癌CasKi细胞生长、诱导Cas-Ki细胞凋亡和对CasKi细胞OPCML、DAPK基因明显的去甲基化作用;其抑制生长和诱导凋亡作用可能与对OPCML、DAPK基因的去甲基化作用有关。TCS有可能是一种新型的甲基化抑制剂。     

紫花牡荆素对宫颈癌HeLa 细胞凋亡及DAPK 基因甲基化的影响

目的探讨紫花牡荆素(casticin)对人宫颈癌HeLa细胞的凋亡和DAPK基因甲基化以及DAPK蛋白表达的影响。方法用不同浓度的casticin处理体外培养的HeLa细胞;AnnexinV-PI染色流式细胞术定量分析细胞凋亡率;DNA琼脂糖凝胶电泳法观察细胞DNA断裂;基因甲基化特异性PCR检测DAPK基因甲基化状态;Western blotting检测DAPK蛋白表达。结果 casticin可以浓度依赖性的方式有效诱导HeLa细胞凋亡;casticin作用于宫颈癌HeLa细胞48小时后,DAPK基因甲基化程度显著降低;casticin以浓度依赖的方式上调DAPK蛋白表达。结论 casticin可能通过使DAPK基因去甲基化上调DAPK蛋白的表达,进而诱导HeLa细胞凋亡。     

异硫氰酸苯己酯诱导Molt-4细胞p15基因去甲基化及机制研究

研究新型组蛋白去乙酰化酶抑制剂异硫氰酸苯己酯（PHI）对急性T淋巴细胞性白血病Molt-4细胞p15基因的去甲基化作用及诱导沉默基因重新表达作用,并进一步探讨其作用机制。应用甲基化特异性聚合酶链反应（MSP）检测PHI作用前后Molt-4细胞株p15基因甲基化状态的变化;半定量逆转录-聚合酶链反应（RT-PCR）检测Molt-4细胞经过PHI处理后DNA甲基转移酶DNMT1、DNMT3A、DNMT3B、p15基因的mRNA的表达变化;用蛋白免疫印迹（Western blotting）检测Molt-4细胞经过PHI处理后的P15蛋白的表达。结果显示,PHI作用于Molt-4细胞5 d后,p15基因的甲基化程度减弱,p15基因的异常高甲基化现象被逆转,沉默的p15基因重新表达,p15 mRNA、P15蛋白表达增加,并呈浓度依赖性;PHI可下调DNMT1和DNMT3B的mRNA表达（P < 0.05）,而对DNMT3A的mRNA表达作用不明显（P > 0.05）。PHI可能通过抑制DNA甲基转移酶DNMT1和DNMT3B的活性,诱导p15基因产生去甲基化,或者（和）是通过改变p15基因附近组蛋白的乙酰化水平,导致染色体空间结构发生变化,增加转录因子的进入,从而诱导p15基因重新表达。
     

The Study of E-cadherin Gene Promoter Demethylation in Nude Mice Burdended-Ovarian Cancer

目的:观察DNA甲基化转移酶(DNMT)抑制剂5-氮杂-2'-脱氧胞苷(5-Aza-CdR)联合组蛋白去乙酰化酶(HDAC)抑制剂苯丁酸钠(SPB)对荷卵巢癌细胞系SKOV3裸鼠上皮钙黏素(E-cad)表达的影响.方法:在已建立的卵巢癌裸鼠腹腔移植瘤模型上,分别应用及两者联合应用5-Aza-CdR、SPB,免疫组化法检测腹腔移植瘤中DNMT1、HDAC1及E-cad的表达变化情况;检测各组移植瘤E-cad基因启动子区5'CpG岛甲基化状况及移植瘤E-cad mRNA和蛋白的表达情况.结果:(1)在对照组中,DNMT1和HDAC1的阳性表达较多,5-Aza-CdR能抑制DNMT1的表达,SPB能抑制HDAC1的表达,差异有统计学意义(P＜0.05).(2)5-Aza-CdR能够诱导E-cad基因去甲基化,使E-cadmRNA及蛋白恢复表达或者表达增强,联合应用5-Aza-CdR和SPB可更大程度上诱导甲基化的E-cad基因去甲基化而恢复mRNA和E-cad蛋白的表达.结论:5-Aza-CdR能够降低E-cad基因启动子区的甲基化,可恢复其表达;联合应用5-Aza-CdR和SPB可产生协同效应,对卵巢癌的治疗有重要作用.     

荷卵巢癌裸鼠肿瘤E-cad启动子去甲基化的研究

目的：观察DNA甲基化转移酶（DNA methyltransferase,DNMT）抑制剂5-氮杂-2'-脱氧胞苷（5-Aza-2'-deoxycytidine,5-Aza-CdR）联合组蛋白去乙酰化酶（histone deacetylase,HDAC）抑制剂苯丁酸钠（Sodium 4-Phenylbutyrate,SPB）对荷卵巢癌细胞系SKOV3裸鼠上皮性钙黏素（epithelial cadherin,E-cad）表达的影响。 方法：在已建立的卵巢癌裸鼠腹腔移植瘤模型上,分别应用或二者联合应用5-Aza-CdR、SPB,免疫组化法检测腹腔移植瘤中DNMT1、HDAC1以及E-cad的表达变化情况;检测各组移植瘤E-cad基因启动子区5’CpG岛甲基化状况及各组移植瘤E-cad mRNA和蛋白的表达变化情况。 结果：①在移植瘤组织中,DNMT1和HDAC1呈高表达,5-Aza-CdR能抑制DNMT1的表达,SPB能抑制HDAC1的表达,与对照组相比,差异显著（P<0.05）。②5-Aza-CdR能够诱导甲基化的E-cad基因去甲基化,从而mRNA及E-cad蛋白恢复表达或者表达增强,联合应用5-Aza-CdR和SPB可更大程度上诱导甲基化的E-cad基因去甲基化而恢复mRNA和E-cad蛋白的表达。 结论：5-Aza-CdR能够降低E-cad基因启动子区的甲基化,可恢复其表达;联合应用5-Aza-CdR和SPB可产生协同效应,显著增强甲基化的E-cad基因的表达,对卵巢癌的治疗有重要作用。     

异硫氰酸苯已酯诱导骨髓瘤U266细胞P16基因去甲基化

目的研究异硫氰酸苯己酯(PHI)对骨髓瘤U266细胞株P16基因的去甲基化作用并探讨其作用机制。方法应用半定量逆转录-聚合酶链反应检测U266细胞经过PHI处理后DNA甲基转移酶DNMT1、DNMT3a和DNMT3b基因的mRNA的表达变化,用甲基化特异性聚合酶链反应检测PHI作用前后U266细胞株P16基因甲基化状态的变化。结果使用不同浓度的PHI处理U266细胞72h后,U266细胞表达DNMT1、DNMT3a、DNMT3bmRNA的水平明显降低并呈浓度依赖性。以不同浓度的PHI处理U266细胞10d后,P16基因的甲基化状态被逐渐逆转。结论 PHI可能通过抑制DNA甲基转移酶的表达水平诱导P16基因产生去甲基化,使失活的抑癌基因重新激活,诱导瘤细胞凋亡。     

宫颈癌细胞系中RASSF2A基因启动子区甲基化状态的研究

目的拟通过检测4株不同宫颈癌细胞系HeLa、CaSki、SiHa和C33A中RASSF2A基因启动子区甲基化水平,以及分析去甲基化前后RASSF2A基因mRNA和蛋白表达水平、甲基化状态及细胞生物活性的变化,探讨宫颈癌发生的可能机制及治疗对策。方法采用实时定量聚合酶链反应方法检测去甲基化药物5-杂氮-2′-脱氧胞苷（5-aza-dC）作用前后RASSF2A基因的表达;甲基化特异性PCR（MSP）法检测4株宫颈癌细胞系中RASSF2A启动子区甲基化状态;免疫细胞化学方法检测RASSF2A基因表达变化,并用MTT法和流式细胞术观察细胞生物活性的变化。结果宫颈癌细胞系HeLa和SiHa表现为完全甲基化状态,细胞系CaSki和C33A表现为部分甲基化状态。5-aza-dC可使宫颈癌细胞系部分去甲基化,并使RASSF2A基因在宫颈癌细胞中mRNA和蛋白水平表达均显著升高。通过对宫颈癌细胞系HeLa的生物学行为检测发现,通过5-aza-dC的诱导作用,其增殖能力和抗凋亡能力明显下降。结论甲基化是导致宫颈癌细胞中RASSF2A基因表达缺失或降低的重要原因之一。去甲基化药物5-aza-dC能够逆转宫颈癌细胞系RASSF2A基因启动子异常甲基化水平,提高RASSF2A基因的mRNA和蛋白表达水平,提示RASSF2A基因的甲基化水平可以作为评估去甲基化干预是否有效的分子学标志物,为宫颈癌的临床治疗提供新的分子靶点。     

Phenylhexyl isothiocyanate induces gene p16 demethylation by down-regulating DNA methyltransferases in U266 cells

目的 研究异硫氰酸苯己酯(PHI)对骨髓瘤U266细胞株P16基因的去甲基化作用并探讨其作用机制.方法 应用半定量逆转录-聚合酶链反应检测U266 细胞经过PHI 处理后DNA 甲基转移酶DNMT1、DNMT3a 和DNMT3b基因的mRNA 的表达变化,用甲基化特异性聚合酶链反应检测PHI 作用前后U266细胞株P16 基因甲基化状态的变化.结果 使用不同浓度的PHI处理U266细胞72 h后,U266细胞表达DNMT1、DNMT3a、DNMT3b mRNA的水平明显降低并呈浓度依赖性.以不同浓度的PHI处理U266细胞10d后,P16基因的甲基化状态被逐渐逆转.结论 PHI 可能通过抑制DNA 甲基转移酶的表达水平诱导P16 基因产生去甲基化,使失活的抑癌基因重新激活,诱导瘤细胞凋亡.     

吸入氢气对脓毒症小鼠海马组织 DNA甲基化的影响

目的 评价吸入氢气对脓毒症小鼠海马组织的 DNA甲基化状态的影响。方法 54只健康雄性 C57BL/6小鼠采用随机数字表法分为 3组：假手术组（Sham组）、脓毒症组（Sepsis组）和氢气治疗组（Sepsis+H2组）,每组 18只。Sepsis组和 Sepsis+H2组采用盲肠结扎穿孔法（CLP）制备小鼠脓毒症模型,Sepsis+H2组小鼠于手术后 1 h和 6 h吸入用空气混合的 2%氢气 1 h,Sham组只开腹不进行盲肠结扎和穿孔。3组小鼠于假手术或 CLP后 1、3、7 d取小鼠海马组织,比色法测定全基因组 DNA甲基化水平;实时定量 PCR法检测 DNA甲基化转移酶（DNMTs,包括 DNMT1、DNMT3a和 DNMT3b）的 mRNA水平;Western blot法检测 DNMT1、DNMT3a和 DNMT3b蛋白表达水平。结果 与 Sham组比较,Sepsis组小鼠在建模后 1、3、7 d海马组织全基因组甲基化水平明显下降（P＜0.05）,DNMT1和 DNMT3a的 mRNA和蛋白表达水平升高,DNMT3b的 mRNA和蛋白表达水平降低（P＜0.05）;与 Sepsis组比较,Sepsis+H2组全基因组甲基化水平升高（P＜0.05）,DNMT1和 DNMT3a的 mRNA和蛋白表达水平下降,DNMT3b的 mRNA和蛋白表达水平升高（P＜0.05）。结论 吸入氢气可纠正脓毒症小鼠海马组织的 DNA甲基化紊乱状态,改善 DNA甲基化紊乱状态是氢气治疗脓毒症相关性脑病的重要机制之一。     

Aberrant methylation accounts for cell adhesion-related gene silencing during 3-methylcholanthrene and diethylnitrosamine induced multistep rat lung carcinogenesis associated with overexpression of DNA methyltransferases 1 and 3a

To evaluate the significance of alterations in cell adhesion-related genes methylation during lung multistep carcinogenesis induced by the genotoxic carcinogens 3-methylcholanthrene (MCA) and diethylnitrosamine (DEN), tissue samples microdissected from MCA/DEN-induced rat lung carcinogenesis model were subjected to methylation-specific PCR to evaluate the DNA methylation status of CADM1, TIMP3, E-cadherin and N-cadherin. Immunohistochemistry was used to determine protein expression of CADM1, TIMP3, N-cadherin and the DNA methyltransferases (DNMTs) 1, 3a and 3b. E-cadherin hypermethylation was not detected in any tissue. CADM1, TIMP3 and N-cadherin hypermethylation was correlated with the loss of their protein expression during the progression of pathologic lesions. The prevalence of DNA methylation of at least one gene and the average number of methylated genes increased with the histological progression. DNMT1 and DNMT3a protein expression increased progressively during the stages of lung carcinogenesis, whereas DNMT3b overexpression was only found in several samples. Furthermore, DNMT1 protein expression levels were correlated with CADM1 methylation, and DNMT3a protein expression levels were correlated with CADM1, TIMP3 and N-cadherin methylation. The average number of methylated genes during carcinogenesis was significantly correlated with DNMT1 and DNMT3a protein expression levels. Moreover, mRNA expression of CADM1 significantly increased after treatment with DNMT inhibitor 5-aza-2′-deoxycytidine in CADM1-methylated primary tumor cell lines. Our findings suggest that an accumulation of hypermethylation accounts for cell adhesion-related gene silencing is associated with dynamic changes in the progression of MCA/DEN-induced rat lung carcinogenesis. We suggest that DNMT1 and DNMT3a protein overexpression may be responsible for this aberrant DNA methylation.     

Effects of subchronic cadmium poisoning on DNA methylation in hens

Cadmium is a persistent pollutant that poses a threat to most biological organisms including birds. Although toxicity of cadmium is mainly linked to cancer, the mechanism of its carcinogenic activity remains poorly understood. Since DNA methylation is linked to cancer, we have examined the effect of cadmium on DNA methylation and DNMTs mRNA expression in hen liver and kidney. Sixty 50-day-old hyline-white hens were randomly allocated into 3 equal groups; a control group fed a basal diet, a low-dose group fed the basal diet spiked with 140 mg/kg CdCl₂, and a high-dose group fed the basal diet spiked with 210 mg/kg CdCl₂. After 60 days, liver and kidney samples were analysed for cadmium by FAAS, DNA methylation level by HPLC and DNMTs mRNA levels by semi-quantitative RT-PCR. The DNA methylation levels and the expressions of DNMT1 and DNMT3a mRNA in liver and kidney were significantly elevated by the cadmium treatment but there was no change in the expression of DNMT3b mRNA in the two tissues. The fact that cadmium increases DNA methylation and the expressions of DNMT1 and DNMT3a mRNA in liver and kidney suggests DNA methylation may be involved in the carcinogenic action of cadmium.     

DNA甲基转移酶 凋亡抑制蛋白在肺癌组织中的表达及意义

目的观察DNA甲基转移酶(DNMT)1、DNMT3β和凋亡抑制蛋白-2(IAP2)在肺癌组织中的表达及与肺癌的临床病理特征关系。方法采用组织微阵列和免疫组织化学技术检测DNMT1、DNMT3β在60例肺癌组织及30名健康人正常肺组织中的表达。结果肺癌组织中DNMT1、DNMT3β、IAP2表达的阳性率均高于正常对照组(P<0.01);3种蛋白的表达在性别、吸烟史、年龄、淋巴结转移、肿瘤分期之间差异无统计学意义(P>0.05);DNMT1、DNMT3β表达与IAP-2的表达明显相关(P<0.01)。结论 DNMT1、DNMT3β表达升高是肺癌形成、发展中的普遍事件,可作为诊断的有效指标,DNMT1与DNMT3β的表达可能存在共同调节机制;且可能参与了凋亡抑制蛋白IAP2调节作用。     

硼替佐米对K562细胞株DNA甲基转移酶表达的影响

目的探讨蛋白酶体抑制剂硼替佐米(bortezomib,商品名:万珂)对K562细胞株DNA甲基转移酶(DNMTs)表达、细胞凋亡的影响。方法常规体外培养白血病K562细胞株,随机将处于对数生长期的细胞分为12、24、36h3个作用时间组,予以不同浓度的硼替佐米:0,6,20,60nmol/L,蛋白印迹法检测胞内DNMT1的表达,流式细胞术检测细胞凋亡。结果与阴性对照组相比,硼替佐米可显著抑制DNMT1表达。硼替佐米作用于细胞12、24、36h后细胞凋亡率逐渐增加,60nmol/L硼替佐米作用36h后细胞凋亡率为(61.68±3.20)%。结论硼替佐米抑制K562细胞株DNMT1表达,诱导细胞凋亡,该作用呈浓度依赖性。     

Epigenetic CpG Demethylation of the Promoter and Reactivation of the Expression of Neurog1 by Curcumin in Prostate LNCaP Cells

Curcumin (CUR), a major bioactive polyphenolic component from turmeric curry, Curcuma longa, has been shown to be a potent anti-cancer phytochemical with well-established anti-inflammatory and anti-oxidative stress effects. Chromatin remodeling-related epigenetic regulation has emerged as an important mechanism of carcinogenesis, chemoprevention, and chemotherapy. CUR has been found to inhibit histone acetyltransferase activity, and it was also postulated to be a potential DNA methyltransferase (DNMT) and histone deacetylase (HDAC) inhibitor. In this study, we show that when human prostate LNCaP cells were treated with CUR, it led to demethylation of the first 14 CpG sites of the CpG island of the Neurog1 gene and restored the expression of this cancer-related CpG-methylation epigenome marker gene. At the protein level, CUR treatment had limited effects on the expression of epigenetic modifying proteins MBD2, MeCP2, DNMT1, and DNMT3a. Using ChIP assay, CUR decreased MeCP2 binding to the promoter of Neurog1 dramatically. CUR treatment showed different effects on the protein expression of HDACs, increasing the expression of HDAC1, 4, 5, and 8 but decreasing HDAC3. However, the total HDAC activity was decreased upon CUR treatment. Further analysis of the tri-methylation of histone 3 at lysine 27 (H3K27me3) showed that CUR decreased the enrichment of H3K27me3 at the Neurog1 promoter region as well as at the global level. Taken together, our present study provides evidence on the CpG demethylation ability of CUR on Neurog1 while activating its expression, suggesting a potential epigenetic modifying role for this phytochemical compound in human prostate cancer cells.     

5-Aza-2′-deoxycytidine,a DNA methylation inhibitor,induces cytotoxicity,cell cycle dynamics and alters expression of DNA methyltransferase 1 and 3A in mouse hippocampus-derived neuronal HT22 cells

Epigenetic processes such as DNA methylation are essential for processes of gene expression in normal mammalian development. DNA methyltransferases (DNMT) are responsible for initiating and maintaining DNA methylation. It is known that 5-Aza-CdR, an inhibitor of DNMT induces cytotoxicity by reducing DNMT activity in various tumor cell lines. However, disturbances in neuronal DNA methylation may also play a role in altered brain functions. Thus, it was of interest to determine whether alterations in DNA methylation might be associated with neuronal functions by using 5-Aza-CdR, on mouse hippocampus-derived neuronal HT22 cell line. In particular, the aim of this study was to investigate the effects of 5-Aza-CdR on cell growth inhibition, cell cycle arrest, apoptosis as well as the expression levels of DNMT in HT22 cells. HT22 cells were incubated with 5 or 20 μmol/L 5-Aza-CdR for 24 h. Data showed that 5-Aza-CdR at both concentrations significantly inhibited proliferation of HT22 cells and exacerbated cytoplasmic vacuolization. Flow cytometry analysis demonstrated that 5-Aza-CdR treatment at both concentrations decreased early apoptosis but enhanced late apoptosis. Cell cycle analysis illustrated that 5-Aza-CdR treatment induced S phase arrest. Further, incubation with 5-Aza-CdR produced a down-regulation in expression of mRNA and protein DNMT1 and 3A but no marked changes were noted in DNMT 3B and p21 expression. In addition, DNMT1 activity was significantly decreased at both 5-Aza-CdR concentrations. Evidence indicates that 5-Aza-CdR induced cytotoxicity was associated with altered mRNA and protein expression of DNMT 1 and 3A associated with reduced DNMT1 activity in HT22 cells which might affect brain functions.     

Mithramycin A inhibits DNA methyltransferase and metastasis potential of lung cancer cells

Abnormal CpG island hypermethylation of multiple tumor-suppressor genes (TSGs) can lead to the initiation and progression of human cancer. The cytosine of the CpG island on the promoter region is methylated by 5'-cytosine-methyltransferases (DNMTs). Pharmacologic inhibitors of CpG island methylation provide a rational approach to reactivate the TSGs in tumor cells and to restore the critical cellular pathways in cancer cells. Mithramycin A (MMA) is known to be a GC- and CG-rich DNA-binding agent. We sought to determine whether MMA could inhibit CpG island methylation and DNMT expression in lung cancer cells. We found that MMA reduced the CpG island methylation of antimetastasis TSGs, including SLIT2 and TIMP-3 genes, and was associated with the prevention of metastasis. When highly metastatic CL1-5 lung cancer cells were treated with low doses (10 nmol/l) of MMA for 14 days, they reexpressed mRNA levels for these genes. MMA also inhibited the invasion phenotypes of CL1-5 cells as indicated by its inhibition of cancer cell migration using wound-healing and transwell assays. Molecular docking of MMA onto the DNMT1 catalytic domain revealed that MMA might interact with the catalytic pocket of DNMT1. Western blots showed that DNMT1 protein levels were depleted after MMA. These data support the idea that MMA has demethylation and antimetastasis effects on lung cancer cells. This mechanism might be mediated by the interaction of MMA and DNMT1, leading to the depletion of the DNMT1 protein and the reversal of the metastasis phenotype in lung cancer cells.     

Ibandronate increases the expression of the pro-apoptotic gene FAS by epigenetic mechanisms in tumor cells

There is growing evidence that aminobisphosphonates like ibandronate show anticancer activity by an unknown mechanism. Biochemically, they prevent posttranslational isoprenylation of small GTPases, thus inhibiting their activity. In tumor cells, activated RAS-GTPase, the founding member of the gene family, down-regulates the expression of the pro-apoptotic gene FAS via epigenetic DNA-methylation by DNMT1. We compared ibandronate treatment in neoplastic human U-2 osteosarcoma and in mouse CCL-51 breast cancer cells as well as in the immortalized non-neoplastic MC3T3-E1 osteoblastic cells. Ibandronate attenuated cell proliferation in all cell lines tested. In the neoplastic cells we found up-regulation of caspases suggesting apoptosis. Further we found stimulation of FAS-expression as a result of epigenetic DNA demethylation that was due to down-regulation of DNMT1, which was rescued by re-isoprenylation by both geranylgeranyl-pyrophosphate and farnesylpyrophosphate. In contrast, ibandronate did not affect FAS and DNMT1 expression in MC3T3-E1 non-neoplastic cells. Data suggest that bisphosphonates via modulation of the activity of small-GTPases induce apoptosis in neoplastic cells by DNA-CpG-demethylation and stimulation of FAS-expression. In conclusion the shown epigenetic mechanism underlying the anti-neoplastic activity of farnesyl-transferase-inhibition, also explains the clinical success of other drugs, which target this pathway.