microRNA在乳腺癌耐药中的作用

乳腺癌是危害全球女性健康的主要疾病,而乳腺癌患者对现有治疗方法产生获得性耐药成为目前乳腺癌临床治疗所面临的难题.微小RNA (miRNA)是一种内源性的非编码RNA,它参与调控多种生物学过程,包括细胞增殖、侵袭、转移、上皮间质转化和耐药等.获得性耐药包含多种复杂机制,可通过特定miRNA的异常表达影响细胞相关蛋白的表达、抗肿瘤药物与相应靶点的结合以及凋亡相关途径引起乳腺癌耐药.本文将重点关注在乳腺癌内分泌治疗、化疗、分子靶向治疗发生获得性耐药中表达异常的miRNA.相信miRNA能够成为乳腺癌临床诊断与治疗以及对抗获得性耐药的生物标志物和新的治疗靶点.     

乳腺癌耐药机制研究进展和应对策略

乳腺癌是女性最常见的恶性肿瘤之一,其分型的多样性与临床治疗密切相关。近年来随着分子生物学的快速发展,乳腺癌的治疗进展迅速,效果显著,但治疗方案产生的耐药仍是临床一线治疗最常遇到的问题。本文就不同类型的乳腺癌及其临床特征进行了分类分析,针对不同分型的治疗方案和耐药机制进行了总结和探讨,旨在通过研究治疗的分子机制和可能存在的耐药机制,对临床治疗起到引导作用。     

微小RNA在乳腺癌耐药中的研究

乳腺癌的多药耐药(MDR)是造成乳腺癌治疗失败的关键因素.微小RNA (miRNA)是一种内源性表达小分子单链RNA,通过与靶基因的信使RNA结合调控基因的转录后表达.miRNA参与乳腺癌耐药形成的多种机制,是治疗耐药乳腺癌的可行靶点.寻找新的miRNA并研究其在乳腺癌耐药中的作用已成为当今研究的热点.     

Non-coding RNA in drug resistance of gastric cancer

Gastric cancer (GC) is the third leading cause of cancer-related mortality worldwide. The poorly prognosis and survival of GC are due to diagnose in an advanced, non-curable stage and with a limited response to chemotherapy. The acquisition of drug resistance accounts for the majority of therapy failure of chemotherapy in GC patients. Although the mechanisms of anticancer drug resistance have been broadly studied, the regulation of these mechanisms has not been completely understood. Accumulating evidence has recently highlighted the role of non-coding RNAs (ncRNAs), including long non-coding RNAs and microRNAs, in the development and maintenance of drug resistance due to their regulatory features in specific genes involved in the chemoresistant phenotype of GC. We review the literature on ncRNAs in drug resistance of GC. This review summarizes the current knowledge about the ncRNAs’ characteristics, their regulation of the genes involved in chemoresistance and their potential as targeted therapies for personalized treatment in resistant GC.     

乳腺癌干细胞抵抗放射治疗及化疗的调控机制

据中国城市癌症报告统计,乳腺癌是中国城市女性发病率最高的癌症。尽管乳腺癌早期原位切除及放射治疗和化疗(简称放化疗)后,患者的5年和10年生存率较好,但依旧有小部分癌细胞逃逸、潜伏和扩散,导致乳腺癌复发和转移。未治愈乳腺癌中,约70%发生肺转移,60%发生骨转移和肝转移,15%发生脑转移。肿瘤干细胞是肿瘤组织中存在的少量具有干细胞特征的细胞亚群,有极强的再生肿瘤能力以及天然放化疗抵抗能力,被视作乳腺癌复发、转移的主要原因。靶向肿瘤干细胞的研究,为人类彻底攻克恶性肿瘤带来了希望。乳腺癌组织中具备乙醛脱氢酶(＋)、CD44^＋ CD24^－Lin^－等特征的细胞亚群已经被证实是乳腺肿瘤干细胞。笔者总结了乳腺肿瘤干细胞的鉴定、起源、特征、调控机制、放化疗不敏感的原因及临床靶向治疗的研究进展,供同行参考。     

外泌体传递非编码RNA调控乳腺癌耐药

耐药性是乳腺癌治疗的重大挑战之一。有多种原因和机制导致乳腺癌耐药的发生。外泌体及其内容物（DNA、mRNA、蛋白质、非编码RNA等）是细胞间通讯的重要介质,在肿瘤进展、转移、复发中发挥作用。其中,外泌体携带的非编码RNA在限制药物疗效方面起着至关重要的作用。本文对国内外关于外泌体非编码RNA与乳腺癌耐药相关的最新研究进展作一综述。     

Exosomes in development,metastasis and drug resistance of breast cancer

Transport through the cell membrane can be divided into active, passive and vesicular types (exosomes). Exosomes are nano‐sized vesicles released by a variety of cells. Emerging evidence shows that exosomes play a critical role in cancers. Exosomes mediate communication between stroma and cancer cells through the transfer of nucleic acid and proteins. It is demonstrated that the contents and the quantity of exosomes will change after occurrence of cancers. Over the last decade, growing attention has been paid to the role of exosomes in the development of breast cancer, the most life‐threatening cancer in women. Breast cancer could induce salivary glands to secret specific exosomes, which could be used as biomarkers in the diagnosis of early breast cancer. Exosome‐delivered nucleic acid and proteins partly facilitate the tumorigenesis, metastasis and resistance of breast cancer. Exosomes could also transmit anti‐cancer drugs outside breast cancer cells, therefore leading to drug resistance. However, exosomes are effective tools for transportation of anti‐cancer drugs with lower immunogenicity and toxicity. This is a promising way to establish a drug delivery system.     

托瑞米芬逆转乳腺癌耐药蛋白介导的多药耐药机制

目的 探讨托瑞米芬逆转乳腺癌耐药蛋白(BCRP)介导的多药耐药机制。方法 通过基因扩增,构建分别由BCRP启动子和巨细胞病毒(CMV)启动子启动表达BCRP的重组质粒pcDNA3-Promoter-BCRP和作为对照的质粒pcDNA3-CMV-BCRP,将其分别转染雌激素受体α（ERα）阳性的MCF-7和ERα阴性的MDA-MB-231乳腺癌细胞系,建立由BCRP启动子和CMV启动子启动表达BCRP的4种耐药细胞系MCF-7/Promoter-BCRP、MCF-7/CMV-BCRP、MDA-MB-231/PromoterBCRP和MDA-MB-231/CMV-BCRP。在耐药细胞培养基中加入托瑞米芬,通过逆转录聚合酶链反应(RT-PCR)、Western blot、外排实验以及细胞毒性实验观察托瑞米芬对不同细胞系的耐药逆转效果。结果与空白对照组（未加药物）相比,托瑞米芬以剂量依赖方式抑制BCRP mRNA的表达,0.1、1和10 μmol/L托瑞米芬处理组MCF-7/Promoter-BCRP细胞中BCRP mRNA的表达水平分别下调29.5％(P＜0.05)、68.1％ (P＜0.01)和97.4％(P＜0.01);MCF-7/Promoter-BCRP细胞经托瑞米芬和17β-雌二醇联合处理后,细胞中BCRP mRNA的相对表达水平为64.2％±1.3％,明显高于托瑞米芬单独处理组(3.8％±0.2％,P＜0.01)。托瑞米芬对各组细胞系中BCRP蛋白表达的调控作用与mRNA相似。经托瑞米芬处理后,MCF-7/Promoter-BCRP细胞内米托蒽醌的荧光强度显著增强,外排米托蒽醌的能力降低了 47.3％ (P ＜0.05);经托瑞米芬和17β-雌二醇联合处理后,MCF-7/Promoter-BCRP细胞内米托蒽醌的荧光强度明显低于托瑞米芬单独处理组,外排米托蒽醌的能力升高了61.5％。托瑞米芬可有效逆转MCF-7/Promoter-BCRP细胞对米托蒽醌的耐药性。上述作用在MCF-7/CMV-BCRP、MDA-MB-231/Promoter-BCRP和MDA-MB-231/CMV-BCRP细胞中未能体现。结论 托瑞米芬可能通过ERot的介导与BCRP启动子上游调控序列中的ERE结合,负性调节BCRP的表达,抑制BCRP蛋白的功能,在体外有效逆转BCRP介导的多药耐药。     

耐药基因对乳腺癌化疗的影响

化疗耐药已成为提高乳腺癌患者治愈率的重要障碍。经典的多药耐药基因（mdrl）及多药耐药相关蛋白（MRP1）等耐药途径和非经典的谷胱甘肽-硫-转移酶π（GST-π）以及DNA拓扑异构酶Ⅱ（TopoⅡ）等耐药途径在影响化疗疗效中均有重要作用。     

多种耐药基因蛋白在初治乳腺癌中的表达

目的:观察乳腺癌多种常见耐药相关基因蛋白的表达情况,探讨乳腺癌原发性耐药的状态及可能机制。方法:选取术前未行化疗及内分泌治疗的369例乳腺癌标本,采用免疫组化法检测LRP、GST、P190及P170的表达情况,观察上述指标之间以及与肿瘤大小、淋巴结转移的相关性。结果:这些基因蛋白表达的阳性率分别为:LRP57.99%,GST32.79%、P1905.96%和P17038.12%;多基因共表达率为40.10%;LRP与P170之间呈正相关(r=0.1702,P<0.001);4种耐药相关基因蛋白表达与肿瘤大小及淋巴结转移之间均无相关性(P>0.05)。结论:初治乳腺癌中存在多个耐药相关基因蛋白表达及共表达,可能反映了乳腺癌的原发性耐药状态及其复杂的机制。     

A literature review of molecular markers predictive of clinical response to cytotoxic chemotherapy in patients with breast cancer

Background  We aimed to identify, through a review of the literature, candidate genes for a prospective predictive chemosensitivity test in patients with breast cancer. Methods  Papers demonstrating an association between gene alterations in tumor tissue and clinical chemosensitivity in breast cancer patients were selected by Medline searches. We calculated odds ratios (ORs) and their 95% confidence intervals (CIs) of response rates for patients who had tumors with or without gene alteration. Combined ORs and CIs were estimated using the DerSimonian-Laird method. Results  A total of 18 genes were evaluated for association with clinical chemosensitivity in 6378 patients registered in 69 studies. The median (range) number of patients in each study was 73 (29–319). Overexpression of ABCB1 (P-glycoprotein) was associated with poor responses to first-line chemotherapy (combined OR [CI], 0.16 [0.05–0.59]; n = 322). Overexpression and amplification of TOP2A (topoisomerase II-alfa) were more frequently observed in patients who responded to first-line chemotherapy (combined OR [CI], 2.73 [1.02–7.27]; n = 323). Overexpression of ERBB2 (c-erbB2) was associated with favorable responses in patients treated with both first-line anthracycline-based chemotherapy and second-line taxane-based chemotherapy (combined ORs [CIs], 1.60 [1.19–2.17]; n = 1807 and 2.24 [1.06–4.74]; n = 259, respectively). BCL2 overexpression was associated with resistance to first-line chemotherapy (combined OR [CI], 0.44 [0.21–0.91]; n = 816). Conclusion   ABCB1, TOP2A, ERBB2, and BCL2 were good candidates for future clinical trials of predictive chemosensitivity tests in patients with breast cancer.     

hsa-miRNA27a和hsa-miRNA451通过调控MDRl/P-gp的表达和功能参与卵巢癌和乳腺癌细胞耐药

背景与目的：肿瘤细胞耐药是临床化疗失败的主要原因,微小RNA(microRNA,miRNA)在肿瘤细胞中的异常表达与耐药关系密切。本研究旨在探讨卵巢癌及乳腺癌细胞中hsa-miRNA27a和hsa-miRNA451的表达差异及其与耐药的关系。方法：用浓度递增法建立卵巢癌耐紫杉醇细胞系A2780/Taxol;颈环状引物实时定量聚合酶链反应(stem-loop quantitative real-time PCR,stem-loop RT-PCR)检测卵巢癌耐紫杉醇细胞A2780/Taxol和亲本细胞A2780以及乳腺癌耐阿霉素细胞MCF-7/ADM和亲本细胞MCF-7中hsa-miRNA27a和hsa-miRNA451的表达;利用Lipofectamine^TM 2000分别将成熟miRNA27a的模拟物、阻遏物及阴性对照(negative control,NC)RNA转染A2780和A2780/Taxol细胞,将成熟miRNA451的模拟物及NC转染MCF-7/ADM细胞;RT-PCR技术检测细胞MDR1 mRNA表达;蛋白[质]印迹法(Western blot)检测细胞中P-糖蛋白(P-glycoprotein,P-gp)的表达;采用四甲基偶氮唑蓝(MTT)法检测细胞增殖情况。结果：miRNA27a在A2780/Taxol细胞中高表达,与A2780细胞相比,表达增高2.2±0.30倍,差异有统计学意义(P<0.05);miRNA451在MCF-7/ADM细胞中低表达,与MCF-7细胞相比,表达降低84%,差异有统计学意义(P<0.05)。A2780/Taxol细胞转染miRNA27a阻遏物后,MDR1 mRNA表达明显下降,与转染NC组相比,表达下降(39±0.14)%,差异有统计学意义(P<0.05)。P-gp相对表达量［(26±5.3)%)］与转染NC组的P-gp相对表达量［(43±6.7)%］比较,下降39%,差异有统计学意义(P<0.05)。对紫杉醇的敏感性增加,半数抑制浓度(IC₅₀)为0.53 μmol/L,与转染NC组IC50(6.8 μmol/L)相比,差异有统计学意义(P<0.05)。A2780细胞转染miRNA27a模拟物后,细胞的MDR1 mRNA表达升高,与转染NC组相比,升高(121±0.11)%,差异有统计学意义(P<0.05);细胞对紫杉醇的敏感性下降,IC₅₀为0.2 μmol/L,与转染NC组IC₅₀(0.06 μmol/L)相比,差异有统计学意义(P<0.05)。MCF-7/ADM细胞转染miRNA451模拟物后,MDR1 mRNA表达明显下降,与转染NC组细胞相比,表达下降(65±12)%,差异有统计学意义(P<0.05);P-gp相对表达量［(31±19)%)］与转染NC组细胞P-gp相对表达量［(83±12)%］相比,下降62%,差异有统计学意义(P<0.05);对阿霉素的敏感性增加,IC₅₀为4.61 μmol/L,与转染NC组细胞IC₅₀(26 μmol/L)相比,差异有统计学意义(P<0.05)。结论：在卵巢癌耐紫杉醇细胞A2780/Taxol和乳腺癌耐阿霉素细胞MCF-7/ADM中,miRNA27a和miRNA451分别异常表达,它们可能分别通过间接或直接作用于MDR1/P-gp,参与肿瘤细胞耐药的发生、发展。     

Current progress in the prediction of chemosensitivity for breast cancer

Advances in chemotherapy have improved the prognosis of patients with breast cancer significantly. Individualization is important for optimization of chemotherapy. The prediction of tumor sensitivity to anticancer agents has been intensively investigated for that purpose. There have been 2 approaches to predict the efficacy of drugs against individual tumors, drug-sensitivity tests and molecular marker genes. Although some of these tests are already available clinically, the prediction of chemosensitivity remains a goal to be achieved. Several studies with microarrays revealed that comprehensive analyses of genes may provide useful information for determining the chemosensitivity of cancer. We have started to use a cDNA microarray to study the chemosensitivity of breast cancer. Taken together with recent data, studies for drug sensitivity should provide insights into the mechanisms of drug sensitivity and the optimal design of more effective treatment strategies in breast cancer.     

晚期乳腺癌紫杉类耐药及其新型抗微管治疗

紫杉类药物原发性或继发性耐药已成为不可避免的棘手难题.伊沙匹隆对经多线治疗包括紫杉类耐药的乳腺癌患者有效.艾日布林用于治疗接受过二线以上化疗的晚期乳腺癌患者.新型抗微管药物有望成为既往接受过紫杉类药物标准化疗的晚期乳腺癌患者的有效方案.     

Diminished feedback regulation of proteasome expression and resistance to proteasome inhibitors in breast cancer cells

Clinical trials with proteasome inhibitor Bortezomib (also named Velcade or PS-341) has shown promising results for some cancers. However, other types of cancers including breast cancer do not respond well to Bortezomib. To understand the cause of the drug resistance, we compared the regulation of proteasome expression and the sensitivity to proteasome inhibitors between human breast cancer cells and nontumorigenic mammary epithelial cells. We found that, while the endogenous expression level is much higher, the potential of feedback expression in response to proteasome inhibitors is much lower in the breast cancer cells. Furthermore, the breast cancer cells are much more resistant to proteasome inhibitors compared to the nontumorigenic mammary epithelial cells. Biochemical analysis showed that the pathway of Bortezomib-induced apoptosis is apparently defective in the breast cancer cells. Together, these results provide an explanation for the inefficacy of Bortezomib in the clinical trials for breast cancer patients. The likelihood of combination therapy with Bortezomib and other anti-cancer agents for breast cancer is also discussed.     

miR-155对乳腺癌细胞增殖、凋亡及耐药蛋白表达的调控作用研究

目的 探讨microRNA-155（miR-155）对乳腺癌MCF-7细胞增殖、凋亡及乳腺癌耐药相关蛋白表达的调控作用。方法 采用实时荧光定量PCR（qRT-PCR）法检测MCF-7细胞和人乳腺正常上皮细胞中miR-155的表达水平。将MCF-7细胞分为4组：对照组、空转染组、抑制（转染miR-155 inhibitor）组和过表达（转染miR-155 mimics）组,采用qRT-PCR检测转染24、48、72及96 h后各组的转染效果,噻唑蓝（MTT）法检测各组转染24、48、72及96 h的增殖能力,采用流式细胞仪PI／Annexin V双染色法检测各组转染24、48 h后的凋亡率,Western blotting法检测各组转染48 h后乳腺癌耐药蛋白（BCRP）、P-糖蛋白（P-gp）及多药耐药相关蛋白1（MRP1）的表达水平。结果 乳腺癌MCF-7细胞中的miR 155水平高于人乳腺正常上皮细胞（P＜0.05）,且转染miR-155 inhibitor或mimics可呈时间依赖的方式降低或升高MCF-7细胞的miR-155水平（P＜0.05）。与对照组相比,抑制组转染后的细胞增殖率及BCRP、P-gp和MRP1的表达水平均降低,凋亡率升高（P＜0.05）;而过表达组的细胞增殖率及BCRP、P gp和MRP1的表达水平均升高,凋亡率降低（P＜0.05）。结论 MCF-7细胞中miR-155呈高表达,下调miR-155表达可抑制其增殖及耐药相关蛋白的表达,同时诱导凋亡。     

乳腺癌上皮-间质转化后引发BCRP介导的多药耐药的研究

背景与目的:研究发现肿瘤的侵袭浸润和转移增强是上皮-间质转化(epithelial mesenchymal transition, EMT)所致,而EMT的发生也与肿瘤细胞多药耐药现象的发生密切相关.本研究通过分析乳腺癌组织和细胞中EMT与乳腺癌耐药蛋白表达的相关性,探讨EMT对乳腺癌中乳腺癌耐药蛋白(breast cancer resistant protein, BCRP)介导多药耐药的影响.方法:免疫组织化学方法检测乳腺癌组织中Snail、BCRP的表达:构建Snail真核表达载体pCDNA3.1-Snail,转染至MCF-7细胞,采用免疫荧光、Western blot、Real-time PCR检测转录抑制因子snail、上皮标志物E-钙粘素、间质标志物vimentin以及多药耐药蛋白BCRP的表达;MTT法检测细胞对米托蒽醌的耐药指数.结果:免疫组化结果显示乳腺癌组织中Snail、BCRP的表达呈显著相关:免疫荧光、Western blot、Real-time PCR显示与亲本MCF-7细胞相比,转染Snail后的MCF-7细胞中E-cadherin表达水平明显降低,而snail、vimentin和BCRP的表达水平明显增加;MTT结果显示细胞对米托蒽醌的耐药指数增加至9.93.结论:转染snail真核表达载体pCDNA3.1-snail可使乳腺癌MCF-7细胞发生EMT, 并导致细胞中BCRP表达增加,引发BCRP介导的多药耐药.     

Small interfering RNA targeting the subunit ATP6L of proton pump V-ATPase overcomes chemoresistance of breast cancer cells

One of the mechanisms of multiple drug resistance (MDR) is inappropriate sequestration of basic chemotherapeutic agents in acidic endo-lysosomes of cells. The protonation, sequestration, and secretion (PSS) model indicates that drug distribution can be affected by intracellular pH such as lysosomal pH. The vacuolar-H⁺-ATPase (V-ATPase) plays an important role in regulation of intracellular pH by pumping protons into acidic endosomes via an ATP-driven process. In this study, ATP6L, the 16 kDa subunit of V-ATPase, was knocked-down by anti-ATP6L small interfering RNA (siRNA) to study the effect on chemosensitivity in the human drug-resistant breast cancer cells MCF-7/ADR. Introduction of anti-ATP6L small interfering RNA duplex into drug-resistant cancer cells significantly inhibited the expression of ATP6L mRNA and protein, as detected by qRT-PCR and Western blot. Inhibition of ATP6L expression by siRNA in MCF-7/ADR sensitized the cells to the cytotoxicity of basic chemotherapeutic agents like doxorobicin, 5-fluorourocil and vincristine. This effect was mediated by a significant increase in lysosomal pH and retention of anticancer drugs into nuclei of cells. These results support the role of tumor acidity in resistance to chemotherapy and provide a rationale for the use of tumor pH modifier agents as coadjuvants in novel anticancer therapies.     

Pregnancy associated breast cancer

Background

Breast carcinoma during pregnancy put the health of the mother in conflict with that of the foetus. The aim is to give optimal treatment to the mother to maximise the chances of survival, whilst minimising the risk of harm of the foetus.We report the epidemiology, pathology, clinical picture, therapeutic management and foetal outcome of pregnant women with breast cancer treated in our institution.

Patients and methods

Twenty-two pregnant breast cancer patients were treated in our hospital from January 1996 to October 2006. Parents were surveyed by mail or telephone regarding outcomes of children exposed to chemotherapy in uterus.

Results

The treatment of breast cancer pregnancy should conform as closely as possible to standardised protocols for patients without concomitant pregnancy. Most of the patients underwent surgery during pregnancy In four cases diagnosed during the first trimester chemotherapy was initiated during the 10th week when organogenesis period was finished. None of the children exposed to chemotherapy during this trimester presented congenital malformations. All 11 cases diagnosed during second and third trimester were treated with Doxorrubicin, Fluoracil and Cyclophosphamide and four cases were treated with taxanes. No congenital malformations were detected.

Conclusion

Breast cancer can be treated with FAC chemotherapy during the second and third trimesters without significant complications for the children exposed to chemotherapy in uterus. We report four cases treated with taxanes after the first trimester and no congenital anomalies were observed.     

紫杉类药物在乳腺癌治疗中的耐药机制

目前研究提示紫杉类耐药可能与多药耐药相关蛋白(MRP)表达增高、Ⅲβ-微管过表达、微管相关蛋白tau的过表达有关,而与HER2的表达成负相关.针对这些耐药靶点可逆转或者延缓紫杉类药物耐药的发生,为临床上更好地使用紫杉类药物提供一定参考.