FOXA1 expression affects the proliferation activity of luminal breast cancer stem cell populations

The expression of estrogen receptor is the key in most breast cancers (BC) and binding of estrogen receptor to the genome correlates to Forkhead protein (FOXA1) expression. We herein assessed the correlation between the cancer stem cell (CSC) population and FOXA1 expression in luminal BC. We established luminal BC cells derived from metastatic pleural effusion and analyzed the potency of CSC and related factors with established luminal BC cell lines. We also confirmed that mammosphere cultures have an increased aldehyde dehydrogenase‐positive population, which is one of the CSC markers, compared with adherent culture cells. Using a quantitative PCR analysis, we found that mammosphere forming cells showed a higher expression of FOXA1 and stemness‐related genes compared with adherent culture cells. Furthermore, the growth activity and colony‐forming activity of 4‐hydroxytamoxifen‐treated BC cells were inhibited in a mammosphere assay. Interestingly, 4‐hydroxytamoxifen‐resistant cells had significantly increased FOXA1 gene expression levels. Finally, we established short hairpin RNA of FOXA1 (shFOXA1) MCF‐7 cells and investigated the relationship between self‐renewal potential and FOXA1 expression. As a result, we found no significant difference in the number of mammospheres but decreased colony formation in shFOXA1 MCF‐7 cells compared with control. These results suggest that the expression of FOXA1 appears to be involved in the proliferation of immature BC cells rather than the induction of stemness‐related genes and self‐renewal potency of CSCs.     

EMT in breast cancer stem cell generation

The concept of cancer stem cells (CSCs) has been proposed to explain the ability of single disseminated cancer cells to reconstitute tumours with heterogeneity similar to that of the primary tumour they arise from. Although this concept is now commonly accepted, the origin of these CSCs remains a source of debate. First proposed to arise through stem/progenitor cell transformation, CSCs might also or alternatively arise from differentiated cancer cells through epithelial to mesenchymal transition (EMT), an embryonic transdifferentiation process. Using breast carcinomas as a study model, I propose revisiting the role of EMT in generating CSCs and the debate on potential underlying mechanisms and biological significance.     

乳腺癌干细胞的研究进展

乳腺癌是女性中常见的恶性肿瘤,其高度的异质性使乳腺癌患者的临床表现、形态学特征以及分子生物学表型均呈现出明显的不一致性,给诊断和治疗带来了很大的困难.肿瘤干细胞具有自我更新能力并能产生异质性的特征,与肿瘤进展、耐药、复发、转移等关系密切.本文对近年乳腺癌干细胞的研究进展作一综述.     

小白菊内酯体内杀伤小鼠乳腺癌肿瘤干细胞

目的： 探讨小白菊内酯（parthenolide,PTL）对小鼠乳腺癌肿瘤干细胞（cancer stem cell,CSC）的杀伤作用,为临床应用PTL治疗乳腺癌提供实验依据。 方法： 采用5-氟尿嘧啶（5-fluorouracil, 5-FU）化疗法制备富含CSC的小鼠4T1细胞乳腺癌模型,随机分为对照组、5-FU组、PTL组。4周后脱颈处死小鼠,检测各组小鼠肿瘤的体积和重量,流式细胞术检测小鼠肿瘤组织中CD44+CD24-/low细胞比例,Hoechst33342染色法检测侧群（side population,SP）细胞的比例,免疫组化法检测CD55和乙醛脱氢酶1（aldehyde dehydrogenase1,ALDH1）蛋白的表达,倒置显微镜观察乳腺癌细胞微球体的形成。 结果： 成功制备富含CSC的小鼠乳腺癌细胞移植瘤模型,PTL可下调小鼠肿瘤组织中CD44+CD24-/low细胞的比例\[（42.5±3.7）% vs （68.7±32）%,P<0.05\],有效降低荷瘤小鼠肿瘤组织中SP细胞的比例\[（39.2±1.8）% vs （61.3±2.6）%,P<0.05\],下调小鼠移植瘤组织中CD55和ALDH1蛋白的表达\[（18.9±1.5）% vs （30.1±1.3）%,（8.1±2.3）% vs （18.0±1.4）%;均P<0.05\],抑制小鼠肿瘤细胞在无血清培养条件下形成微球体,并可抑制小鼠移植瘤的体积和重量\[（0.625±0.159）cm3 vs （1.715±0184）cm3,（1.467±0.373）g vs （3.367±0.398）g;均P<0.05\]。 结论： PTL在荷瘤小鼠体内可以明显降低肿瘤组织CSC含量,提示PTL可用来靶向杀伤乳腺癌CSC。     

Epithelial-mesenchymal transition and cancer stem cells: a dangerously dynamic duo in breast cancer progression

Aberrant activation of a latent embryonic program - known as the epithelial-mesenchymal transition (EMT) - can endow cancer cells with the migratory and invasive capabilities associated with metastatic competence. The induction of EMT entails the loss of epithelial characteristics and the de novo acquisition of a mesenchymal phenotype. In breast cancer, the EMT state has been associated with cancer stem cell properties including expression of the stem cell-associated CD44⁺/CD24^-/low antigenic profile, self-renewal capabilities and resistance to conventional therapies. Intriguingly, EMT features are also associated with stem cells isolated from the normal mouse mammary gland and human breast reduction tissues as well as the highly aggressive metaplastic and claudin-low breast tumor subtypes. This has implications for the origin of these breast tumors as it remains unclear whether they derive from cells that have undergone EMT or whether they represent an expansion of a pre-existing stem cell population that expresses EMT-associated markers to begin with. In the present review, we consider the current evidence connecting EMT and stem cell attributes and discuss the ramifications of these newly recognized links for our understanding of the emergence of distinct breast cancer subtypes and breast cancer progression.     

Cancer stem cell heterogeneity in hereditary breast cancer

The cancer stem cell hypothesis proposes that tumors arise in stem or progenitor cells generating in tumors driven by a subcomponent that retains cancer stem cell properties. Recent evidence supports the hypothesis that the BRCA1 gene involved in hereditary breast cancer plays a role in breast stem cell function. Furthermore, studies using mouse BRCA1 knockout models provide evidence for the existence of heterogeneous cancer stem cell populations in tumors generated in these mice. Although these populations may arise from different stem/progenitor cells, they share the expression of a common set of stem cell regulatory genes and show similar characteristics in in vitro mammosphere assays and xenograft models. Furthermore, these 'cancer stem cells' display resistance to chemotherapeutic agents. These studies suggest that breast tumors may display intertumor stem cell heterogeneity. Despite this heterogeneity, cancer stem cells may share common characteristics that can be used for their identification and for therapeutic targeting.     

Insights into the cell of origin in breast cancer and breast cancer stem cells

The precise cell types that give rise to tumors and mechanisms that underpin tumor heterogeneity are poorly understood. There is increasing evidence to suggest that diverse solid tumors are hierarchically organized and may be sustained by a distinct subpopulation of cancer stem cells (CSCs). The CSC hypothesis provides an attractive cellular mechanism that can account for the therapeutic refractoriness and dormant behavior exhibited by many tumor types. Breast cancer was the first solid malignancy from which CSCs were identified and isolated. Direct evidence for the CSC hypothesis has also recently emerged from mouse models of mammary tumorigenesis, although alternative models to explain heterogeneity also seem to apply. Our group has found that the luminal epithelial progenitor marker CD61/β3 integrin identified a CSC population in mammary tumors from MMTV‐wnt‐1 mice. However, no CSCs could be identified in the more homogeneous MMTV‐neu/erbB2 model, suggesting an alternate (clonal evolution or stochastic) model of tumorigenesis. It seems likely that both paradigms of tumor propagation exist in human cancer. From a clinical perspective, the CSC concept has significant implications. Quiescent CSCs are thought to be more resistant to chemotherapy and targeted therapy. Enrichment of putative CSCs has been noted in studies of chemotherapy‐treated patients, lending support to the CSC hypothesis and their potential role in chemoresistance. Although many unresolved questions on CSCs remain, ongoing efforts to identify and characterize CSCs continue to be an important area of investigation, with the potential to identify novel tumor targeting strategies.     

Lack of correlation of stem cell markers in breast cancer stem cells

Background:

Various markers are used to identify the unique sub-population of breast cancer cells with stem cell properties. Whether these markers are expressed in all breast cancers, identify the same population of cells, or equate to therapeutic response is controversial.

Methods:

We investigated the expression of multiple cancer stem cell markers in human breast cancer samples and cell lines in vitro and in vivo, comparing across and within samples and relating expression with growth and therapeutic response to doxorubicin, docetaxol and radiotherapy.

Results:

CD24, CD44, ALDH and SOX2 expression, the ability to form mammospheres and side-population cells are variably present in human cancers and cell lines. Each marker identifies a unique rather than common population of cancer cells. In vivo, cells expressing these markers are not specifically localized to the presumptive stem cell niche at the tumour/stroma interface. Repeated therapy does not consistently enrich cells expressing these markers, although ER-negative cells accumulate.

Conclusions:

Commonly employed methods identify different cancer cell sub-populations with no consistent therapeutic implications, rather than a single population of cells. The relationships of breast cancer stem cells to clinical parameters will require identification of specific markers or panels for the individual cancer.     

Mammary stem cell number as a determinate of breast cancer risk

The 'cancer stem cell hypothesis' posits that cancers, including breast cancer, arise in tissue stem or progenitor cells. If this is the case, then it follows that the risk for developing breast cancer may be determined in part by the number of breast stem/progenitor cells that can serve as targets for transformation. Stem cell number may be set during critical windows of development, including in utero, adolescence, and pregnancy. The growth hormone/insulin-like growth factor-1 axis may play an important role in regulating breast stem cell number during these developmental windows, suggesting an important link between this signaling pathway and breast cancer risk.     

Dynamic equilibrium between cancer stem cells and non-stem cancer cells in human SW620 and MCF-7 cancer cell populations

Background:

Cancer stem cells (CSCs) paradigm suggests that CSCs might have important clinical implications in cancer therapy. Previously, we reported that accumulation efficiency of CSCs is different post low- and high-LET irradiation in 48 h.

Methods:

Cancer stem cells and non-stem cancer cells (NSCCs) were sorted and functionally identified through a variety of assays such as antigen profiles and sphere formation. Inter-conversion between CSCs and NSCCs were in situ visualised. Cancer stem cells proportions were assayed over multiple generations under normal and irradiation surroundings. Supplement and inhibition of TGF-β1, as well as immunofluorescence assay of E-cadherin and Vimentin, were performed.

Results:

Surface antigen markers of CSCs and NSCCs exist in an intrinsic homoeostasis state with spontaneous and in situ visualisable inter-conversions, irrespective of prior radiations. Supplement with TGF-β1 accelerates the equilibrium, whereas inhibition of TGF-β signalling disturbs the equilibrium and significantly decreases CSC proportion. Epithelial mesenchymal transition (EMT) might be activated during the process.

Conclusion:

Our results indicate that the intrinsic inter-conversion and dynamic equilibrium between CSCs and NSCCs exist under normal and irradiation surroundings, and TGF-β might have important roles in the equilibrium through activating EMT.     

By promoting cell differentiation,miR-100 sensitizes basal-like breast cancer stem cells to hormonal therapy

Basal-like breast cancer is an aggressive tumor subtype with a poor response to conventional therapies. Tumor formation and relapse are sustained by a cell subset of Breast Cancer Stem Cells (BrCSCs). Here we show that miR-100 inhibits maintenance and expansion of BrCSCs in basal-like cancer through Polo-like kinase1 (Plk1) down-regulation. Moreover, miR-100 favors BrCSC differentiation, converting a basal like phenotype into luminal. It induces the expression of a functional estrogen receptor (ER) and renders basal-like BrCSCs responsive to hormonal therapy. The key role played by miR-100 in breast cancer free-survival is confirmed by the analysis of a cohort of patients’ tumors, which shows that low expression of miR-100 is a negative prognostic factor and is associated with gene signatures of high grade undifferentiated tumors. Our findings indicate a new possible therapeutic strategy, which could make aggressive breast cancers responsive to standard treatments.     

乳腺癌化疗耐药中肿瘤干细胞的作用及其机制

目的:了解肿瘤干细胞在乳腺癌化疗耐药中的作用及其相关机制的研究进展。方法:应用检索Pubmed及CNKI数据库检索系统,以肿瘤、干细胞、乳腺癌、化疗和耐药等为关键词,检索1999-01-2011-05的相关文献,纳入标准:肿瘤干细胞与乳腺癌化疗耐药。根据纳入标准分析42篇文献。结果:肿瘤干细胞是导致乳腺癌化疗耐药和治疗失败的主要细胞,其耐药的机制包括ATP结合盒转运子的过度表达、细胞解毒酶的过度活化、细胞存活和凋亡相关信号转导通路的异常激活、肿瘤壁龛对肿瘤干细胞的保护作用以及大部分肿瘤干细胞处于静止期。通过对这些耐药机制的干预,可以逆转肿瘤干细胞的耐药性。结论:肿瘤干细胞是导致乳腺癌化疗耐药的关键细胞,对其耐药机制的研究有助于展开针对肿瘤干细胞的靶向治疗,改善患者的预后。     

新辅助化疗对乳腺癌细胞周期及干细胞的影响

目的：探讨新辅助化疗对乳腺癌患者细胞周期中 G0-G1期细胞比例以及三磷酸腺苷结合转运蛋白 G 超家族成员2（ABCG2）、CD44＋CD24－／low表达的影响。方法选取2013年5月至2014年3月收治的60例经空芯针穿刺活检明确病理诊断的初治乳腺浸润性导管癌患者为研究对象,比较化疗前后乳腺癌细胞周期中 G0-G1期细胞比例及 ABCG2、CD44＋CD24－／low 含量的变化。结果患者化疗后ABCG2为（25．10±1．50）％,CD44＋CD24－／low 为（36．40±3．80）／105,G0-G1期细胞比例为（70．50±1．50）％,均高于化疗前的（15．88±1．22）％、（25．00±3．40）／105、（60．65±1．30）％,差异具有统计学意义（t ＝8．685,P ＜0．05;t ＝9．226,P ＜0．05;t ＝8．898,P ＜0．05）。所有患者完成4个疗程的化疗后,cCR率、cPR 率、SD 率分别为18．3％（11／60）、73．3％（44／60）、8．3％（5／60）。结论新辅助化疗后患者肿瘤细胞发生周期阻滞,肿瘤干细胞比例上升,疗效确切,具有临床推广价值。     

Separation of breast cancer stem cell and its heterogeneity

The successful separation of breast cancer stem cell (BCSC) is the foundation of BCSC research. At present, people could gather BCSC to some extent in a number of ways. However, as more and more biomarkers are found in BCSC separation, the heterogeneity becomes a hot spot. How to gather BCSC as much as possible and how to explain the heterogeneity could provide new insights in the treatment of breast cancer.     

乳腺癌干细胞的分离方法探讨

乳腺癌干细胞是首次被分离出的实体肿瘤干细胞,由于缺乏特异的细胞表面标志,如何获得纯化的乳腺癌干细胞已经成为乳腺癌研究的热点.目前存在的几种常用的乳腺癌干细胞的分离方法都各有利弊,现就乳腺癌干细胞的分离方法作一综述.     

乳腺癌干细胞的分离方法探讨

乳腺癌干细胞是首次被分离出的实体肿瘤干细胞,由于缺乏特异的细胞表面标志,如何获得纯化的乳腺癌干细胞已经成为乳腺癌研究的热点。目前存在的几种常用的乳腺癌干细胞的分离方法都各有利弊,现就乳腺癌干细胞的分离方法作一综述。     

乳腺癌干细胞分选及其异质性

乳腺癌干细胞的成功分选是进行乳腺癌干细胞研究的基础,目前人们可以通过多种方法使乳腺癌干细胞得到一定程度的富集.然而,在越来越多乳腺癌干细胞表面标志物被发现的同时,其异质性也成为人们关注的热点.如何最大程度地富集乳腺癌干细胞及解释其异质性,将为乳腺癌的干细胞治疗提供新思路.     

造血干细胞移植治疗乳腺癌研究进展

乳腺癌对化放疗敏感，常规的综合治疗可使相当部分患者长期无病生存，但对复发和高危乳腺癌患者效果不佳。造血干细胞移植（HSCT）技术为晚期、高危乳腺癌的治疗带来了新的选择。     

乳腺癌干细胞乙醛脱氢酶1分子表型与化疗预后的相关性研究

目的探讨乳腺癌干细胞乙醛脱氢酶1(ALDH1)分子表型与临床特征及不同化疗方案预后的相关性。方法选取2014年2月至2016年12月间河北省沧州市人民医院收治的140例乳腺浸润性导管癌患者,采用免疫组化法对癌组织石蜡块进行ALDH1+分子表型检测。采用随机数表法分为观察组与对照组,每组70例。观察组患者采用表阿霉素+紫杉醇(ET方案)治疗,对照组患者采用环磷酰胺+表阿霉素+氟尿嘧啶(CEF方案)治疗,采用免疫组化法分析乳腺癌干细胞分子表型与新辅助化疗预后的相关性。结果患者ALDH1阳性率为26.4%,ALDH1表达水平与患者组织学分级、肿瘤直径和淋巴结转移有关,差异均有统计学意义(均P<0.05)。两组患者的总有效率比较,差异无统计学意义(P>0.05)。对37例ALDH1阳性患者采用不同化疗方案短期疗效进行比较,其中接受CEF方案治疗的17例患者总有效率为58.8%,20例接受ET方案治疗患者的总有效率为85.0%,差异有统计学意义(P<0.05)。结论乳腺癌组织ALDH1阳性表达可能是该类患者短期预后相关的独立影响因素,ALDH1+乳腺癌患者对ET化疗方案敏感性更高。