乳腺癌肿瘤内异质性的驱动因素及临床研究进展

乳腺癌是第一种根据患者肿瘤的分子特征指导临床选择治疗策略的恶性肿瘤。然而,无论是基于免疫组织化学的分子分型还是基于基因组分析的固有分型,均存在一定的缺陷,二者不能完全解释乳腺癌预后和治疗的临床异质性。肿瘤内异质性（intratumoral heterogeneity,ITH）理论与乳腺癌的分型理论不同,异质性理论是指在同一肿瘤中存在多个不同亚型（空间异质性）,并且肿瘤在不同时期不同表型间可相互转化（时间异质性）。这些异质性是由肿瘤细胞状态异质性和克隆进化驱动,同时受肿瘤微环境、代谢重编程的协同影响。对肿瘤内异质性ITH的研究可进一步解释乳腺癌转移和耐药机制,有望成为潜在的新型治疗靶点。本文将对乳腺癌ITH的驱动因素和临床意义的研究进展进行综述。      

乳腺癌的分子分型与肿瘤治疗的相关性

乳腺癌是女性最常见的肿瘤之一,因其肿瘤组织具有高度异质性、多种组织亚型,因而产生不同临床表现、不同治疗反应以及不同预后.传统评价乳腺癌预后的因素包括:发病年龄、肿瘤大小、临床分期、淋巴结转移等.近年来,基于基因表达谱不同提出的乳腺癌分子分型研究不断深入,为乳腺癌的个体化治疗提供了一个有力的依据.本文从乳腺癌的固有分子分型入手,描述不同分子分型的特点及其临床结局的差异,着重阐述不同分子分型与乳腺痛局部复发的关系,同时对其他分子分型进行简要分析,以期对乳腺癌分子分型有一个全面的了解并为临床治疗方案的制定提供依据.     

曲妥珠单抗耐药机制及HER2阳性乳腺癌耐药后的治疗策略

曲妥珠单抗治疗人表皮生长因子受体2(Human epidermal growth factor receptor 2,HER2)阳性乳腺癌的效果确切,但高耐药率限制了其临床应用。本文对HER2阳性乳腺癌曲妥珠单抗耐药机制进行回顾与总结,并分析耐药后HER2阳性乳腺癌的治疗策略,以期为进一步的研究及临床治疗方案制定提供参考。     

拉帕替尼在乳腺癌中的应用及其耐药机制研究现状

随着分子肿瘤学的发展,乳腺癌进入了分子分型时代。基于患者不同生物标志物表达的个体化医疗已经成为目前乳腺癌治疗的模式。HER2阳性乳腺癌侵袭性高、预后差,占所有乳腺癌患者的20%~30%。曲妥珠单抗作为第一个人源化单克隆抗体,以HER2为靶点,改善了这部分患者的预后,因此乳腺癌相关各大临床实践指南和专家共识明确推荐HER2阳性乳腺癌患者不同阶段均可以使用曲妥珠单抗进行抗HER2治疗。但是曲妥珠单抗的心脏毒性及原发、继发耐药等问题迫使临床医生对二线抗HER2治疗进行探索。拉帕替尼作为第一个被批准用于临床作用于HER1和HER2双靶点的酪氨酸激酶抑制剂,是曲妥珠单抗失败后的不错选择。本文对拉帕替尼在乳腺癌中的应用、相关临床研究及其耐药机制研究进行简要综述。     

miRNA在乳腺癌化疗耐药中的作用

总结近期国内外有关miRNA在乳腺癌化疗耐药中作用的研究进展。应用Pubmed和CNKI期刊全文数据库检索系统以“miRNA、乳腺癌和化疗耐药”为关键词,检索2000年1月至2012年10月有关在乳腺癌化疗耐药中作用的文献。从乳腺癌化疗耐药入手,阐述乳腺癌化疗耐药的特点、机制,并着重对miRNA在乳腺癌化疗耐药中的作用进行分析。miRNA通过多种途径参与乳腺癌的化疗耐药。本文具体综述了一些以不同机制参与肿瘤耐药的miRNA,及其具体参与耐药的途径。探讨了血清miRNA作为肿瘤标记物的潜在临床利用性。结论:深入研究血清miRNA在乳腺癌耐药中的作用和机制,必将为乳腺癌的靶向治疗掀起一个新的篇章。      

乳腺癌内分泌治疗耐药相关机制的研究进展

内分泌治疗作为雌激素受体（estrogen receptor,ER）阳性乳腺癌的主要治疗方案被广泛应用。他莫西芬（tamoxifen,Tam）是乳腺癌内分泌治疗最常用的药物,它通过与雌激素竞争性结合ERα来降低雌激素的生物学活性,抑制细胞的增殖,从而治疗乳腺癌。然而,肿瘤细胞所表现出的原发性或获得性的他莫西芬耐药使得其临床应用受到了限制,寻找克服他莫西芬耐药的治疗策略已经刻不容缓。目前为止,他莫西芬耐药的相关机制已部分明确,但仍需进一步研究。有证据表明ERα、生长因子受体信号通路及microRNA的表达异常等多种机制均与他莫西芬耐药有关。本文对他莫西芬耐药的相关机制进行了具体分析,以期为ER阳性乳腺癌的治疗提供新思路。     

克服乳腺癌内分泌耐药的靶向治疗新进展

内分泌治疗是激素受体阳性乳腺癌最有效的治疗方式,然而其有效性通常受到耐药的制约,这在进展期乳腺癌患者中几乎是不可避免的。最近,有许多研究对这些耐药模式的分子机制进行了探索,但仍未阐明其确切的机制,不过许多研究都将雌激素受体和生长因子受体信号通路之间的相互作用视为雌激素依赖性乳腺癌内分泌耐药的关键点。一些研究还探讨了介导内分泌耐药的不同分子途径,并对一些治疗靶点进行了评估。尽管大多数信号通路靶向制剂都还处于Ⅰ期或小范围Ⅱ期临床试验阶段,但一些研究已取得令人鼓舞的结果。本文旨在对乳腺癌内分泌治疗耐药的新进展进行综述。     

循环肿瘤细胞人表皮生长因子受体2的检测对乳腺癌诊治意义的研究进展

乳腺癌治疗已进入分类治疗的时代。随着对乳腺癌发生发展分子机制的深入了解和乳腺癌分子标志的准确检测,对乳腺癌进行分子分型,并根据不同分子表型进行靶向治疗是目前乳腺癌治疗的重要方向。ER、PR、HER-2是临床常用的分子指标,是明确的预后指标和治疗的预测指标。     

三阳性乳腺癌的病理特征及治疗分析

三阳性乳腺癌(TPBC)是以雌激素受体(ER)、孕激素受体(PR)和人表皮生长因子受体2(HER2)均阳性表达为特征的乳腺癌.虽然发病率较低,但该类型乳腺癌腋窝淋巴结转移和远处转移都较早发生.因此,TP-BC的病理特征被国内外学者广泛关注.对于TPBC,理论上化疗、内分泌治疗、靶向治疗及联合治疗均具有敏感性,治疗效果较好,但在实际临床治疗中,TPBC的治疗情况并未达到期望效果.其独特的耐药机制引起了研究者的高度重视,如何合理地选择治疗方式,避免过早的耐药事件发生是目前临床医师工作中面临的重点、难点问题.因此,更好地研究TPBC的病理特征及耐药机制从而为其治疗提供最优方案是目前研究的热点.本文就TPBC的病理特征、耐药机制及治疗进展进行综述.     

晚期雌激素受体阳性乳腺癌的治疗进展

针对晚期雌激素受体阳性乳腺癌虽然主要使用内分泌、靶向等治疗方法，但内分泌治疗的耐药问题在临床上较常见。随着对CDK4/6、PI3K-Akt1-mTOR通路等治疗靶点和耐药机制的研究，晚期雌激素受体阳性乳腺癌的靶向治疗已成为研究热点，利用基因靶向治疗等也可能成为新的突破点，同时在如何针对不同患者选择最佳治疗方案、最佳治疗时间等问题上仍存在挑战。本文将就晚期雌激素受体阳性乳腺癌的治疗进展进行综述。      

The role of efflux pumps in drug-resistant metastatic breast cancer: new insights and treatment strategies

Chemotherapy plays a vital role in the treatment and management of breast cancer and is associated with significant improvements in survival. Regimens such as CMF (cyclophosphamide/methotrexate/5-fluorouracil) and, more recently, TAC (docetaxel/doxorubicin/cyclophosphamide) have been used with good response rates and complete remissions achieved in approximately 15% of cases. However, a significant proportion of women experience a recurrence of metastatic disease, with an average survival between 1-2 years. The monoclonal antibody trastuzumab is used in the treatment of HER2/neu-positive breast cancer. Although such targeted agents have heralded an exciting new era in cancer therapy, they are limited by the fact that only a subset of patients can benefit from treatment and by the emergence of resistance. Thus, the pursuit of a strategy that modulates resistance to standard chemotherapeutics remains valid. Accumulating evidence indicates that a number of mechanisms known to contribute to clinical drug resistance might be relevant to breast cancer. Tumor cell drug resistance might arise as a result of systemic pharmacologic factors, changes in the tumor microenvironment (eg, pH), cellular pharmacokinetics, drug metabolism and detoxification, drug target modifications, DNA repair, and apoptotic mechanisms. The adenotriphosphate-binding cassette membrane transporter family contributes to clinical drug resistance, especially in breast cancer. The most frequently described of this family is P-glycoprotein, followed by multidrug resistance protein-1. This review describes the factors thought to play a role in clinical breast cancer drug resistance and describes potential methods by which it might be circumvented.     

Extracellular vesicles in breast cancer drug resistance and their clinical application

Drug resistance currently represents a daunting challenge in the treatment of breast cancer patients. With an increased understanding of the underlying mechanisms of drug resistance, the role of extracellular vesicles (EVs) in the development of chemo-insensitivity attracts extensive attention. EVs are membrane-limited, cell type-dependent vesicles that are secreted by normal or malignant cells. EVs comprise various types of contents, including genetic cargoes, proteins, and specific lipids. The characteristics of the contents determine their specific functions in not only physiological but also pathological conditions. It has been demonstrated that miRNAs and proteins in EVs are strongly correlated with breast cancer drug resistance. Additionally, they may exert an influence on de novo and acquired resistance bioprocesses. With the advances in extraction and detection technologies, EVs have also been employed to precisely diagnose and predict the outcome of therapy in breast cancer. On the other hand, they can also be exploited as efficient delivery system in future anticancer applications. In this paper, we summarized relative mechanisms concerning the relationship between EVs and breast cancer drug resistance, and then, we provide up-to-date research advances in the clinical application of EVs.     

乳腺癌芳香化酶抑制剂耐药的研究进展

乳腺癌是女性常见的恶性肿瘤,约70%的患者为雌激素受体（estrogen receptor,ER）和（或）孕激素受体（progesterone receptor,PR）阳性,内分泌治疗是激素受体（hormone receptor,HR）阳性乳腺癌的主要治疗方式之一。近几十年来,内分泌治疗药物不断发展并应用于临床,乳腺癌患者的复发转移风险显著降低,预后得到长足改善。芳香化酶抑制剂（aromatase inhibitor,AI）在乳腺癌内分泌治疗中发挥重要作用,然而绝大部分患者会发生原发性或继发性耐药,因此克服内分泌治疗药物耐药对进一步提高临床疗效至关重要。从遗传学、表观遗传学及细胞内信号转导通路等方面对HR阳性乳腺癌患者AI治疗后耐药的机制及最新的研究进展进行综述,以期为临床诊疗及科研提供参考。     

长链非编码RNA在乳腺癌中的研究进展

乳腺癌为女性最常见的恶性肿瘤，是女性癌症相关死亡的第二大原因。乳腺癌缺乏特异性的肿瘤标志物，目前影像学和传统的血清标志物难以及时有效的监测肿瘤的发生发展及耐药的发生，导致临床治疗效果不佳，因此早期诊断、早期治疗提高临床治疗效益，使患者生存率及生活质量提高尤其重要。多项研究证实长链非编码RNA(long non-coding RNA，lncRNA)在乳腺癌中异常表达，并与乳腺癌的发生发展、预后、耐药等密切相关，lncRNA可以作为治疗或是诊断乳腺癌新的生物靶点。本文通过总结lncRNA近年来的研究进展，旨在为乳腺癌的诊治过程提供新的方案。     

Metformin in breast cancer: preclinical and clinical evidence

Metformin, a well-acknowledged biguanide, safety profile and multiaction drug with low cost for management of type 2 diabetes, makes a first-class candidate for repurposing. The off-patent drug draws huge attention for repositioned for anticancer drug delivery recently. Still few unanswered questions are challenging, among them one leading question; can metformin use as a generic therapy for all breast cancer subtypes? And is metformin able to get over the problem of drug resistance? The review focused on the mechanisms of metformin action specifically for breast cancer therapy and overcoming the resistance; also discusses preclinical and ongoing and completed clinical trials. The existing limitation such as therapeutic dose specifically for cancer treatment, resistance of metformin in breast cancer and organic cation transporters heterogeneity of the drug opens up a new pathway for improved understanding and successful application as repurposed effective chemotherapeutics for breast cancer. However, much more additional research is needed to confirm the accurate efficacy of metformin treatment for prevention of cancer and its recurrence.     

Inhibition of metadherin sensitizes breast cancer cells to AZD6244

The development of systemic therapy drug resistance for breast cancer treatment is an ongoing problem, thus, so are the potential molecular mechanisms of it. AZD6244 is a novel ATP-uncompetitive inhibitor to MAP/ERK kinase (MEK) 1/2 which has been demonstrated to be potent, selective and safe in the clinical trials and previous studies. However, the precise role of resistance to AZD6244 is largely unknown. We and other groups have reported that the novel oncogene Metadherin (MTDH) is associated with multiple drug resistance, but there is no report about its role in treatment of AZD6244. Here we report that the resistance to AZD6244 can be reserved by downregulating MTDH in breast cancer cell lines. When the MTDH was downregulated, the breast cancer cells exhibited a significantly increased sensitivity to AZD6244 as measured by MTT assay. After treated with AZD6244 the MTDH-knockdown cells showed more apoptosis rate and growth inhibition. We also showed that knockdown of MTDH cannot only increase expression of FOXO3a but also activate it by promoting its translocation via MTDH/ERK1/2/FOXO3a pathway rather than MTDH/AKT/FOXO3a pathway. In conclusion knockdown MTDH can enhance the breast cancer cells sensitivity to AZD6244 via regulating the expression and activity of FOXO3a. These indicate us that MTDH is a candidate marker to predict the clinical efficacy of AZD6244 and targeting MTDH could overcome the resistance to AZD6244 in breast cancer cells.     

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.     

Mechanisms and consequences of chemotherapy resistance in breast cancer

Resistance to chemotherapy is a substantial clinical problem limiting the effectiveness of anticancer drug treatment. Resistance accounts for treatment failure in more than 90% of patients with metastatic disease. Overcoming mechanisms of resistance is crucial for the effective management of breast cancer, particularly once the disease has metastasised. However, approaches to reverse multi-drug resistance (MDR) have so far met with limited success. Targeted therapies are now well established in the clinic. Developmental agents with improved specificity for tumour cells also show promise. In addition, novel cytotoxics such as the epothilones, which have low susceptibility to some of the common types of drug resistance and have demonstrated activity in taxane-resistant breast cancer, also show promise. We are now in a new era for cancer therapeutics where there are increasing treatment options for oncology patients. There is, therefore, some optimism for the improvement in the management and survival of patients with metastatic breast cancer.