shRNA抑制c-fos表达对P-gp介导的乳腺癌多药耐药的影响

多药耐药(multidrug resistance,MDR)是导致化疗失败的重要原因,多药耐药基因(multidrug resistance gene,mdr1)产物P-糖蛋白(P-glycoprotein,P-gp)过表达是最主要的耐药机制。原癌基因c-fos在肿瘤MDR中的作用渐受重视。主要选用人乳腺癌敏感株MCF-7和阿霉素(adriamycin,ADR)筛选的、mdr1/P-gp高表达的耐药株MCF-7/ADR,探讨c-fos在P-gp介导的乳腺癌MDR中的作用。相对于MCF-7,c-fos在MCF-7/ADR高表达。采用shRNA法下调c-fos表达后,MCF-7/ADR对ADR的敏感性大大增强,且mdr1/P-gp表达减少、P-gp外排功能降低。c-fos表达下调可逆转对P-gp介导的乳腺癌MDR的实验结果,为c-fos成为逆转肿瘤耐药诊断和治疗的新靶标,对实现耐药乳腺癌的分子靶向治疗提供了理论基础。     

PI3K/AKT 通路参与调控乳腺癌多药耐药和侵袭转移的研究

目的:探讨磷脂酰肌醇-3-激酶/丝苏氨酸蛋白激酶(phosphatidylinositol 3 kinase/serine-threonine kinase,PI3K/AKT)信号通路与乳腺癌多药耐药和侵袭转移的相关性。方法:以乳腺癌细胞系MCF-7为母本,持续低浓度加药诱导建立阿霉素(Adriamycin,ADR)耐药系MCF-7/ADR’。细胞免疫荧光检测两细胞系中磷酸化AKT(phosphorylated AKT,P-AKT)、P-糖蛋白(P-Glycoprotein,P-gp)、基质金属蛋白酶2(matrix metalloproteinase-2,MMP-2)的表达。PI3K抑制剂LY294002作用两系前后,Western Blot检测P-AKT、MMP-2、P-gp的表达改变及qRT-PCR检测MMP-2、MDR1的表达改变。结果:P-AKT、P-gp(MDR1)、MMP-2在MCF-7中为低表达或不表达,MCF-7/ADR’中为高表达。LY294002作用两系后,P-AKT、P-gp(MDR1)、MMP-2在MCF-7/ADR’中的表达明显减低(P<0.05),MCF-7无明显改变。结论:抑制PI3K/AKT信号通路可有效降低MCF-7/ADR’耐药和侵袭转移能力,PI3K/AKT通路是调控乳腺癌多药耐药和侵袭转移的重要信号通路之一。     

C-erbB2与乳腺癌三苯氧胺耐药细胞生长关系的研究

目的:探讨获得性三苯氧胺(TAM)抵抗乳腺癌细胞的生长调节途径及三苯氧胺(TAM)获得性抵抗的发生机制。方法:TAM诱导野生型人乳腺癌细胞系MCF-7/WT构建TAM抵抗的细胞系MCF-7/TAMR,RT-PCR、Western blot及免疫细胞化学方法比较MCF-7/TAMR与MCF-7/WT细胞系中C-erbB2 mRNA、蛋白表达及其活化状态的不同,用C-erbB2单克隆抗体herceptin对两种细胞系进行干预,观察细胞生长变化。结果:与MCF-7/WT细胞相比,MCF-7/TAMR细胞中CerbB-2的mRNA增加3倍(P＜0．05)．蛋白增加1．5倍(P＜0．05)．Herceptin处理MCF-7/TAMR细胞,明显抑制了细胞的生长。结论:表皮生长因子受体特异性配体的自分泌释放作用可能通过CerbB-2/MAPK途径引起MCF-7/TAMR细胞的生长。     

RNA甲基化酶WTAP对乳腺癌MCF-7和耐阿霉素MCF-7/ADR细胞迁移的影响

为了深入探讨乳腺癌治疗耐药的发生机制并寻找乳腺癌治疗耐药的潜在治疗手段,我们以乳腺癌MCF-7和耐阿霉素MCF-7/ADR细胞为研究对象,研究RNA甲基化酶WTAP对其迁移的影响。MTT试验发现阿霉素对MCF-7细胞活力的抑制作用大于对MCF-7/ADR细胞的抑制作用。qPCR和western-blot试验发现WTAP在耐阿霉素细胞MCF-7/ADR中高表达,同时transwell试验发现在MCF-7细胞中增加WTAP的表达对MCF-7细胞的迁移没有影响,而在MCF-7/ADR细胞中敲低WTAP的表达会抑制MCF-7/ADR细胞的迁移。western-blot试验进一步证明了这一作用是通过抑制上皮间质转化(EMT)来发挥的。这一发现有助于为乳腺癌的临床治疗提供新的理论依据并为乳腺癌的治疗提供新的策略。     

C—erbB2与乳腺癌三苯氧胺耐药细胞生长关系的研究

目的：探讨获得性三苯氧胺（TAM）抵抗乳腺癌细胞的生长调节途径及三苯氧胺（TAM）获得性抵抗的发生机制。方法：TAM诱导野生型人乳腺癌细胞系MCF-7/WT构建TAM抵抗的细胞系MCF-7／TAMR,RT—PCR、Westem blot及免疫细胞化学方法比较MCF-7／TAMR与MCF-7/WT细胞系中C—erbB2mRNA、蛋白表达及其活化状态的不同,用C—erbB2单克隆抗体herceptin对两种细胞系进行干预。观察细胞生长变化。结果：与MCF-7/WT细胞相比,MCF-7／TAMR细胞中cerbB-2的mRNA增加3倍（P〈0．05）,蛋白增加1．5倍（P〈0．05）。Herceptin处理MCF-7／TAMR细胞,明显抑制了细胞的生长。结论：表皮生长因子受体特异性配体的自分泌释放作用可能通过CerbB-2／MAPK途径引起MCF-7／TAMR细胞的生长。     

白血病耐药细胞系U937/ADR的建立及其生物学性状

目的：建立白血病耐药细胞系U937/ADR模型,并检测其多药耐药相关基因及其生物学性状的改变。方法：以大剂量阿霉素(IC50浓度),短时间(2h)暴露法诱导人白血病细胞系U937细胞的阿霉素耐药性。检测细胞的生长曲线,计算阿霉素耐药倍数,流式细胞术分析细胞周期分布;罗丹明123检测药物外排功能;荧光定量PCR（FQ-PCR）检测MDR1、MRP1、NF-Κb、Bcl-2、Bax mRNA水平变化;Western blot 检测Akt、p-Akt、P65、P-gp、MRP1和Bcl-2蛋白水平变化。结果：成功构建耐阿霉素U937/ADR细胞系,对阿霉素耐药指数为亲代U937细胞的11倍,U937/ADR群体倍增时间为43.6h,高于亲代细胞8.9h;流式细胞分析显示与U937细胞相比,U937/ADR的G0/G1期细胞增多,而G2/M期细胞减少。并对多种化疗药物产生交叉耐药性。罗丹明123外排试验显示,U937/ADR细胞外排明显增加。U937/ADR细胞MDR1、NF-Κb、Bcl-2 mRNA表达水平明显增加,P-gp及p-Akt、P65表达水平增加。结论：成功构建的U937/ADR细胞系其生物学特性明显不同与亲代U937细胞,对多种化疗药物产生多药耐药,高表达多药耐药蛋白P-gp,同时激活p-Akt及NF-Kb。     

miR-34c逆转乳腺癌耐药细胞株MCF-7/DOX耐药性的研究

miR-34在肿瘤发生发展中起着至关重要的作用,然而,mi R-34在肿瘤耐药中的作用研究不多。该研究将合成的mi R-34c成熟序列转染乳腺癌阿霉素(doxorubicin,DOX)耐药细胞MCF-7/DOX,探讨mi R-34c体外逆转MCF-7/DOX细胞耐药性作用及其可能的机制。采用Real-time RT-PCR检测mi R-34c在乳腺癌耐药细胞株MCF-7/DOX中的表达,MTS法检测miR-34c对MCF-7/DOX细胞阿霉素耐药性的影响,流式细胞术检测miR-34c对MCF-7/DOX细胞周期和凋亡的影响,Real-time RT-PCR和Western blot法检测多药耐药相关蛋白MDR、MRP以及细胞周期与凋亡相关蛋白Bcl-2、E2F3的表达。结果显示,mi R-34c在乳腺癌MCF-7/DOX耐药细胞中低表达,转染mi R-34c可明显增加耐药细胞对阿霉素的敏感性;流式分析发现,miR-34c可以促进耐药细胞G2期细胞周期阻滞和凋亡;与对照组相比较,miR-34c转染组细胞MDR、MRP蛋白表达无明显变化,而Bcl-2、E2F3 mRNA和蛋白表达均明显下调。研究表明,miR-34c直接靶向抑制Bcl-2和E2F3的表达,诱导细胞周期G2期阻滞和凋亡,进而增强MCF-7/DOX耐药细胞对阿霉素的敏感性。     

沉默AEG-1基因逆转乳腺癌MCF-7/ADM细胞耐药性

本研究旨在分析星形细胞上调基因1(astrocyte elevated gene-1,AEG-1)对乳腺癌MCF-7/ADM细胞化疗药物耐药性的影响,并探讨其作用机制。将MCF-7/ADM细胞在含1.0 mg/L阿霉素(adriamycin,ADM)的培养液中培养以维持细胞的耐药性;应用shRNA技术沉默乳腺癌MCF-7/ADM细胞中AEG-1基因表达;采用MTT比色法检测ADM对MCF-7/ADM的细胞耐毒作用,据以计算ADM的半数抑制浓度(IC50);流式细胞术检测细胞凋亡;Western blot方法检测AEG-1、p53和多药耐药基因1(multidrug resistance gene 1,MDR1)蛋白的表达水平以及Akt、MDM2和Bad的磷酸化水平。结果显示,乳腺癌MCF-7/ADM细胞的AEG-1蛋白水平显著高于MCF-7细胞(P0.05),经shRNA干扰后AEG-1蛋白水平显著降低(P0.05);沉默AEG-1基因能显著降低ADM对MCF-7/ADM细胞的IC50(P0.05),促进MCF-7/ADM细胞凋亡(P0.05),并增强ADM对MCF-7/ADM细胞的促凋亡作用,抑制Akt、MDM2和Bad的磷酸化(P0.05),促进p53蛋白表达(P0.05),降低MDR1蛋白表达水平(P0.05)。结果表明,沉默AEG-1基因可通过促进MCF-7/ADM细胞凋亡和下调MDR1蛋白表达,以逆转MCF-7/ADM细胞对ADM的耐药性。     

上皮细胞黏附分子增强细胞间紧密连接促进乳腺癌细胞耐药

乳腺癌是致死率很高的恶性肿瘤,由ABCG2 (ATP-binding cassette G2)介导的多药耐药(multidrug resistance,MDR)是导致其化疗失败的重要原因,探讨ABCG2介导的耐药机制并探寻其关键分子是当前亟待解决的难题。上皮细胞黏附分子(epithelial cell adhesion molecule,EpCAM)参与多种肿瘤耐药,且与乳腺癌MDR密切相关,但它在ABCG2介导的乳腺癌耐药中的作用尚未阐明。本研究目的在于探究EpCAM对于ABCG2介导的乳腺癌细胞的多药耐药的调节作用及其机制。CCK8细胞毒性结果证实,相对于人乳腺癌药物敏感株MCF-7,耐药株MCF-7/MX对米托蒽醌(mitoxantrone,MX)的耐药性显著增强;Western 印迹结果显示,与MCF-7相比,MCF-7/MX细胞中ABCG2高表达,EpCAM表达上调。siRNA法敲低MCF-7/MX细胞中EpCAM可下调其ABCG2表达,并恢复对MX的敏感性。倒置显微镜观察细胞形态,发现敲低EpCAM可减少MCF-7/MX细胞间连接。免疫荧光双染法观察到EpCAM与密封蛋白1(claudin 1)在MCF-7/MX细胞共定位;进一步Western 印迹结果表明,敲低EpCAM减少MCF-7/MX细胞中密封蛋白1表达。综上所述,EpCAM可能通过与密封蛋白1相互作用,增强细胞间紧密连接,促进ABCG2介导的乳腺癌多药耐药。     

两株耐紫杉醇人乳腺癌细胞MCF-7的比较

建立稳定的肿瘤多药耐药(MDR)细胞株是肿瘤MDR机制研究的基础,以MCF-7细胞林为亲本细胞株,采用低浓度加量持续诱导和高浓度短期作用分别建立MCF-7/Taxola和MCF-7/Taxolb细胞模型,并对其耐药谱、动力学周期变化、表形变化、细胞侧群分布、药物蓄积等生物学特性比较评价.结果表明,MCF-7/Taxola和MCF-7/Taxolb细胞的紫杉醇(paclitaxel/Taxol)半数抑制浓度(IC50)分别是亲代MCF-7细胞的525倍和330倍,并且都对多种化疗药物交叉耐药;MCF-7/Taxola细胞S期细胞显著增加,G,期细胞减少;MCF-7/Taxolb细胞各个期变化不大;MCF-7/Taxola细胞P-糖蛋白(P-gP)、肺耐药相关蛋白(LRP)和还原型谷胱甘肽-S转移酶(GSTπ)的表达水平较亲代有显著增加,而MCF-7/Taxolb细胞GSTπ的表达水平较亲代也有显著增加,另外,拓扑异构酶Ⅱ(ToPoⅡ)在两株耐药细胞中表达都明显下降,而两株细胞雌激素受体(ER)、孕激素受体(PR)阳性都表达丢失;光镜下耐药细胞MCF-7/Taxola明显变大并且形态不规则而MCF-7/Taxolb变化不大;电镜下MCF-7/Taxolb表面纤绒毛成小球状隆起和絮状,而MCF-7/Taxolb表面成絮状:MCF-7/Taxola撤药10天后细胞中有紫杉醇蓄积,而MCF-7/Taxolb中没有紫杉醇蓄积.两个模型都具有MDR的基本生物学特性,可用于肿瘤MDR机制的研究,通过两种耐药细胞的比较,推测MCF-7/Taxolb细胞是MCF-7/Taxola细胞的一个亚群.     

Small-molecule synthetic compound norcantharidin reverses multi-drug resistance by regulating Sonic hedgehog signaling in human breast cancer cells

Multi-drug resistance (MDR), an unfavorable factor compromising treatment efficacy of anticancer drugs, involves upregulated ATP binding cassette (ABC) transporters and activated Sonic hedgehog (Shh) signaling. By preparing human breast cancer MCF-7 cells resistant to doxorubicin (DOX), we examined the effect and mechanism of norcantharidin (NCTD), a small-molecule synthetic compound, on reversing multidrug resistance. The DOX-prepared MCF-7R cells also possessed resistance to vinorelbine, characteristic of MDR. At suboptimal concentration, NCTD significantly inhibited the viability of DOX-sensitive (MCF-7S) and DOX-resistant (MCF-7R) cells and reversed the resistance to DOX and vinorelbine. NCTD increased the intracellular accumulation of DOX in MCF-7R cells and suppressed the upregulated the mdr-1 mRNA, P-gp and BCRP protein expression, but not the MRP-1. The role of P-gp was strengthened by partial reversal of the DOX and vinorelbine resistance by cyclosporine A. NCTD treatment suppressed the upregulation of Shh expression and nuclear translocation of Gli-1, a hallmark of Shh signaling activation in the resistant clone. Furthermore, the Shh ligand upregulated the expression of P-gp and attenuated the growth inhibitory effect of NCTD. The knockdown of mdr-1 mRNA had not altered the expression of Shh and Smoothened in both MCF-7S and MCF-7R cells. This indicates that the role of Shh signaling in MDR might be upstream to mdr-1/P-gp, and similar effect was shown in breast cancer MDA-MB-231 and BT-474 cells. This study demonstrated that NCTD may overcome multidrug resistance through inhibiting Shh signaling and expression of its downstream mdr-1/P-gp expression in human breast cancer cells.     

The inhibitory effect of kokusaginine on the growth of human breast cancer cells and MDR-resistant cells is mediated by the inhibition of tubulin assembly

The emergence of multidrug resistance (MDR) is a significant challenge in breast carcinoma chemotherapy. Kokusaginine isolated from Dictamnus dasycarpus Turcz. has been reported to show cytotoxicity in several human cancer cell lines including breast cancer cells MCF-7. In this study, kokusaginine showed the potent inhibitory effect on MCF-7 multidrug resistant subline MCF-7/ADR and MDA-MB-231 multidrug resistant subline MDA-MB-231/ADR. Kokusaginine markedly induced apoptosis in a concentration-dependent manner in MCF-7/ADR cells. Furthermore, kokusaginine reduced P-gp mRNA and protein levels, and suppressed P-gp function especially in MCF-7/ADR cells. In addition, kokusaginine showed to inhibit tubulin assembly and the binding of colchicine to tubulin by binding directly to tubulin and affects tubulin formation in vitro. Taken together, these results support the potential therapeutic value of kokusaginine as an anti-MDR agent in chemotherapy for breast carcinoma.     

Chloride channel-3 mediates multidrug resistance of cancer by upregulating P-glycoprotein expression

Chloride channel-3 (ClC-3), a member of the ClC family of voltage-gated Cl⁻ channels, is involved in the resistance of tumor cells to chemotherapeutic drugs. Here, we report a new mechanism for ClC-3 in mediating multidrug resistance (MDR). ClC-3 was highly expressed in the P-glycoprotein (P-gp)-dependent human lung adenocarcinoma cell line (A549)/paclitaxel (PTX) and the human breast carcinoma cell line (MCF-7)/doxorubicin (DOX) resistant cells. Changes in the ClC-3 expression resulted in the development of drug resistance in formerly drug-sensitive A549 or MCF-7 cells, and drug sensitivity in formerly drug-resistant A549/Taxol and MCF-7/DOX cells. Double transgenic MMTV-PyMT/CLCN3 mice with spontaneous mammary cancer and ClC-3 overexpression demonstrated drug resistance to PTX and DOX. ClC-3 expression upregulated the expression of MDR1 messenger RNA and P-gp by activating the nuclear factor-κB (NF-κB)-signaling pathway. These data suggest that ClC-3 expression in cancer cells induces MDR by upregulating NF-κB-signaling-dependent P-gp expression involving another new mechanism for ClC-3 in the development of drug resistance of cancers.     

KLF4 overcomes tamoxifen resistance by suppressing MAPK signaling pathway and predicts good prognosis in breast cancer

Tamoxifen resistance represents a daunting challenge to the successful treatment for breast cancer. Krüppel-like factor 4 has critical roles in the development and progression of breast cancer, but its expression, function and regulation in the efficacy of TAM therapy in breast cancer have yet to be investigated. Here, we examined the clinical significance and biologic effects of KLF4 in breast cancer. Firstly, higher expression of KLF4 correlated with increased TAM sensitivity in breast cancer cells, and analysis of GEO datasets indicated that KLF4 expression was positively correlated with ERα and enhanced expression of KLF4 sensitized breast cancer patients to endocrine therapy. Knockdown of KLF4 in MCF-7 and BCAP37 cells led to increased TAM resistance, while ectopic KLF4 expression promoted the responsiveness to TAM in T47D and TAM-resistant MCF-7/TAM cells. Secondly, ectopic KLF4 overexpression suppressed MCF-7/TAM cell growth, invasion and migration. Moreover, KLF4 expression was down-regulated in breast cancer tumor tissues and high expression of KLF4 was associated with favorable outcomes. Mechanistically, KLF4 may enhance the responsiveness of breast cancer cells to TAM through suppressing mitogen-activated protein kinase (MAPK) signaling pathway. We found that ERK and p38 were more activated in MCF-7/TAM compared with MCF-7, and treatment with MAPK-specific inhibitors significantly suppressed cell viability. Knockdown of KLF4 activated ERK and p38 and drove MCF-7 cells to become resistant to TAM. Conversely, overexpression of KLF4 in MCF-7/TAM cells suppressed ERK and p38 signaling and resulted in increased sensitivity to TAM. Therefore, our findings suggested that KLF4 contributed to TAM sensitivity in breast cancer via phosphorylation modification of ERK and p38 signaling. Collectively, this study highlighted the significance of KLF4/MAPK signal interaction in regulating TAM resistance of breast cancer, and suggested that targeting KLF4/MAPK signaling may be a potential therapeutic strategy for breast cancer treatment, especially for the TAM-resistant patients.     

Metabolomic approach to evaluating adriamycin pharmacodynamics and resistance in breast cancer cells

Continuous exposure of breast cancer cells to adriamycin induces high expression of P-gp and multiple drug resistance. However, the biochemical process and the underlying mechanisms for the gradually induced resistance are not clear. To explore the underlying mechanism and evaluate the anti-tumor effect and resistance of adriamycin, the drug-sensitive MCF-7S and the drug-resistant MCF-7Adr breast cancer cells were used and treated with adriamycin, and the intracellular metabolites were profiled using gas chromatography mass spectrometry. Principal components analysis of the data revealed that the two cell lines showed distinctly different metabolic responses to adriamycin. Adriamycin exposure significantly altered metabolic pattern of MCF-7S cells, which gradually became similar to the pattern of MCF-7Adr, indicating that metabolic shifts were involved in adriamycin resistance. Many intracellular metabolites involved in various metabolic pathways were significantly modulated by adriamycin treatment in the drug-sensitive MCF-7S cells, but were much less affected in the drug-resistant MCF-7Adr cells. Adriamycin treatment markedly depressed the biosynthesis of proteins, purines, pyrimidines and glutathione, and glycolysis, while it enhanced glycerol metabolism of MCF-7S cells. The elevated glycerol metabolism and down-regulated glutathione biosynthesis suggested an increased reactive oxygen species (ROS) generation and a weakened ability to balance ROS, respectively. Further studies revealed that adriamycin increased ROS and up-regulated P-gp in MCF-7S cells, which could be reversed by N-acetylcysteine treatment. It is suggested that adriamycin resistance is involved in slowed metabolism and aggravated oxidative stress. Assessment of cellular metabolomics and metabolic markers may be used to evaluate anti-tumor effects and to screen for candidate anti-tumor agents.     

Sensitization of multidrug-resistant malignant cells by liposomes co-encapsulating doxorubicin and chloroquine through autophagic inhibition

Adenosine triphosphate (ATP)-binding cassette (ABC) transporters play a key role in the development of multidrug resistance (MDR) in cancer cells. P-glycoprotein (P-gp) and multidrug resistance-associated protein 1 (MRP1) are important proteins in this superfamily which are widely expressed on the membranes of multidrug resistance (MDR) cancer cells. Besides, upregulation of cellular autophagic responses is considered a contributing factor for MDR in cancer cells. We designed a liposome system co-encapsulating a chemotherapeutic drug (doxorubicin hydrochloride, DOX) and a typical autophagy inhibitior (chloroquine phosphate, CQ) at a weight ratio of 1:2 and investigated its drug resistance reversal mechanism. MTT assay showed that the IC₅₀ of DOX/CQ co-encapsulated liposome in DOX-resistant human breast cancer cells (MCF7/ADR) was 4.7?±?0.2?μM, 5.7-fold less than that of free DOX (26.9?±?1.9 μM), whereas it was 19.5-fold in doxorubicin-resistant human acute myelocytic leukemia cancer cells (HL60/ADR) (DOX/CQ co-encapsulated liposome 1.2?±?0.1?μM, free DOX 23.4?±?2.8?μM). The cellular uptake of DOX increased upon addition of free CQ, indicating that CQ may interact with P-gp and MRP1; however, the expressions of P-gp and MRP1 remained unchanged. In contrast, the expression of the autophagy-related protein LC3-II increased remarkably. Therefore, the mechanism of MDR reversal may be closely related to autophagic inhibition. Evaluation of anti-tumor activity was achieved in an MCF-7/ADR multicellular tumor spheroid model and transgenic zebrafish model. DOX/CQ co-encapsulated liposome exerted a better anti-tumor effect in both models than that of liposomal DOX or DOX alone. These findings suggest that encapsulating CQ with DOX in liposomes significantly improves the sensitivity of DOX in DOX-resistant cancer cells.     

Systematic expression analysis of genes related to multidrug-resistance in isogenic docetaxel- and adriamycin-resistant breast cancer cell lines

Docetaxel (Doc) and adriamycin (Adr) are two of the most effective chemotherapeutic agents in the treatment of breast cancer. However, their efficacy is often limited by the emergence of multidrug resistance (MDR). The purpose of this study was to investigate MDR mechanisms through analyzing systematically the expression changes of genes related to MDR in the induction process of isogenic drug resistant MCF-7 cell lines. Isogenic resistant sublines selected at 100 and 200 nM Doc (MCF-7/100 nM Doc and MCF-7/200 nM Doc) or at 500 and 1,500 nM Adr (MCF-7/500 nM Adr and MCF-7/1,500 nM) were developed from human breast cancer parental cell line MCF-7, by exposing MCF-7 to gradually increasing concentrations of Doc or Adr in vitro. Cell growth curve, flow cytometry and MTT cytotoxicity assay were preformed to evaluate the MDR characteristics developed in the sublines. Some key genes on the pathways related to drug resistance (including drug-transporters: MDR1, MRP1 and BCRP; drug metabolizing-enzymes: CYP3A4 and glutathione S-transferases (GST) pi; target genes: topoisomerase II (TopoIIα) and Tubb3; apoptosis genes: Bcl-2 and Bax) were analyzed at RNA and protein expression levels by real time RT-qPCR and western blot, respectively. Compared to MCF-7/S (30.6 h), cell doubling time of MCF-7/Doc (41.6 h) and MCF-7/Adr (33.8 h) were both prolonged, and the cell proportion of resistant sublines in G1/G2 phase increased while that in S-phase decreased. MCF-7/100 nM Doc and MCF-7/200 nM Doc was 22- and 37-fold resistant to Doc, 18- and 32-fold to Adr, respectively. MCF-7/500 nM Adr and MCF-7/1,500 nM Adr was 61- and 274-fold resistant to Adr, three and 12-fold to Doc, respectively. Meantime, they also showed cross-resistance to the other anticancer drugs in different degrees. Compared to MCF-7/S, RT-qPCR and Western blot results revealed that the expression of MDR1, MRP1, BCRP, Tubb3 and Bcl-2 were elevated in both MCF-7/Doc and MCF-7/Adr, and TopoIIα, Bax were down-regulated in both the sublines, while CYP3A4, GST pi were increased only in MCF-7/Doc and MCF-7/Adr respectively. Furthermore, the changes above were dose-dependent. The established MCF-7/Doc or MCF-7/Adr has the typical MDR characteristics, which can be used as the models for resistance mechanism study. The acquired process of MCF-7/S resistance to Doc or Adr is gradual, and is complicated with the various pathways involved in. There are some common resistant mechanisms as well as own drug-specific changes between both the sublines.