乳腺癌干细胞研究现状

肿瘤干细胞理论认为肿瘤可能是由肿瘤干细胞和其所处微环境产生,而肿瘤干细胞由正常干细胞突变而来.乳腺癌干细胞是第一个在实体瘤中被鉴定的肿瘤干细胞,人们采用多种策略成功分离出乳腺癌干细胞,对其生物学行为的认识正逐渐深入.乳腺癌干细胞的自我更新、分化等特性受到微环境和许多信号转导通路的调控.如何靶向治疗乳腺癌干细胞,最终根治乳腺癌,正逐渐成为肿瘤靶向治疗研究的一个热点.     

肿瘤干细胞与滑膜肉瘤相关研究进展

20世纪50年代Makino等[1]通过肿瘤细胞自体移植实验发现肿瘤组织中极少数细胞具有干细胞特性能诱发新的肿瘤组织,首次提出肿瘤干细胞（cancerstem cells,CSCs）理论.该理论认为,肿瘤干细胞作为一类特殊的干细胞,具有自我更新能力和分化潜能,以及高致瘤性和耐药性的特点,可以通过分化为肿瘤细胞而产生肿瘤,即认为肿瘤干细胞是肿瘤启动、增殖生长、转移复发的根源.     

肿瘤干细胞及其与CD133的关系

越来越多的证据支持肿瘤干细胞理论,肿瘤可以认为是一个被少数肿瘤干细胞驱动的异常器官,它们具有自我更新和多向分化潜能.CD133在许多肿瘤中相继被报道,尽管其生物学功能还不清楚,但目前已经是一个非常有价值的分选肿瘤干细胞的标志,研究发现CD133+肿瘤细胞与肿瘤发生、侵袭、转移、耐药及复发有着密切的关系,因此深入了解CD133+肿瘤细胞的分子生物学特性对寻求有效的抗癌治疗,特别是靶向肿瘤干细胞的治疗是相当必要的.     

乳腺癌干细胞研究进展:从基础到临床

干细胞是一类具有自我更新和多向分化潜能的原始细胞,在一定条件下,可以分化成多种不同功能的细胞.基于干细胞的特性,在恶性肿瘤研究中提出了肿瘤干细胞理论,解释了肿瘤的发生、发展、复发和转移等生物学行为.乳腺癌干细胞是实体肿瘤干细胞研究进展较快的一个领域,但是乳腺癌干细胞理论及其如何应用于临床治疗尚存在较多问题.本文就这些问题及其展望进行综述.     

肿瘤干细胞研究进展

目的:了解近年来肿瘤千细胞的研究进展.方法:应用检索Pubmed数据库检索系统,以"肿瘤"、"干细胞"、"肿瘤干细胞"为关键词,检索1979-01-2008-12的相关文献,共检索到英文文献2 760条.纳入标准:1)肿瘤干细胞的表面标志、耐药机制、信号传导通路;2)肿瘤干细胞来源;3)肿瘤干细胞与肿瘤临床诊治的联系.根据纳入标准,最后精选33篇文献进行分析综述.结果:肿瘤干细胞能够自我更新和分化,具有特异的表面分子标志,对放化疗不敏感.肿瘤干细胞存在Wnt、Notch、Hedgehog、Bmi-1等调节细胞自我更新信号通路异常.肿瘤干细胞是维持肿瘤生长、复发和转移的根源,已经成为抗肿瘤研究的靶细胞.结论:肿瘤干细胞研究进展迅速,深入研究肿瘤干细胞的特性,对恶性肿瘤的诊断,治疗和预后评估具有重要意义.肿瘤干细胞理论将改变目前肿瘤的诊治模式.     

肿瘤干细胞的多样性起源及其相应机制的研究进展

肿瘤干细胞理论认为绝大多数肿瘤起源于肿瘤干细胞,且只有肿瘤干细胞具有无限增殖、多向分化和体内外形成异质性肿瘤的能力,然而关于肿瘤干细胞的起源仍有争论.目前的研究提示肿瘤干细胞的起源或许是多样性的,可以起源于组织干细胞、间充质干细胞以及不同程度分化了的组织细胞,甚至非成瘤的普通肿瘤细胞在一定条件下也可能转化成肿瘤干细胞.本文就肿瘤干细胞的多样性起源及其相应机制作一综述.     

甲状腺肿瘤干细胞研究进展

肿瘤干细胞已经成为肿瘤发病机制的研究热点,并且已经在很多肿瘤中发现并分离出了肿瘤干细胞.甲状腺肿瘤干细胞模型也已经被提出,越来越多的实验研究支持甲状腺肿瘤干细胞的存在,并认为他们可能来源于甲状腺干细胞.本文综述了目前甲状腺干细胞和甲状腺肿瘤干细胞的研究进展.     

肿瘤干细胞标志物与胃癌关系的研究进展

肿瘤干细胞（cancer stem cell,CSCs）是理论认为肿瘤中存在一小部分细胞具有自我更新和多向分化的潜能,具有特异性表面标志的细胞.目前已经从乳腺癌、结直肠癌、皮肤癌等多种恶性肿瘤中鉴定分离出了各自的肿瘤干细胞标志物.本文就与胃癌相关的干细胞标志物进行综述.     

肿瘤干细胞:起源与争论

近年来,随着干细胞理论在肿瘤研究中的广泛应用,人们逐渐认识到在绝大多数癌症中,肿瘤细胞很可能起源于一种肿瘤起始细胞———肿瘤干细胞,它在机体内具有自我更新并形成肿瘤的能力。肿瘤干细胞的存在已在多种肿瘤类型与细胞系中得到证实,并鉴定出相应的分选方法,但人们对它的起源却莫衷一是,干细胞突变、细胞融合、胚胎干细胞残留等都有可能是肿瘤干细胞产生的原因。通过多年对肝癌的研究,笔者提出肝癌干细胞来源的假说:认为干细胞在修复肝炎病毒所致肝损伤的过程中,在病毒与炎症的双重刺激下,干细胞与突变肝细胞之间发生细胞融合、交换,最终产生肝癌干细胞。随着相关研究的不断深入,肿瘤干细胞学说在理论与技术上也面临着诸多质疑与挑战,其中有观点认为,干细胞可能只是被趋化至癌变部位并因其可塑性而表现出恶变表型,但并未在实质上参与肿瘤的发生与发展。     

肿瘤干细胞真的存在吗?

肿瘤干细胞是个令人激动的概念,其假说似乎回答了肿瘤起源的问题.然而从肿瘤中分离出的细胞是否为真正的肿瘤干细胞还存在理论、技术和数学方面的疑问.本文分析肿瘤干细胞不存在的可能性.     

Cancer Stem Cells and Response to Therapy

The cancer stem cell (CSC) model states that cancers are organized in cellular hierarchies, which explains the functional heterogeneity often seen in tumors. Like normal tissue stem cells, CSCs are capable of self-renewal,either by symmetric or asymmetric cell division, and have the exclusive ability to reproduce malignant tumors indefinitely. Current systemic cancer therapies frequently fail to eliminate advanced tumors, which may be dueto their inability to effectively target CSC populations. It has been shown that embryonic pathways such as Wnt, Hedgehog, and Notch control self-renewal and cell fate decisions of stem cells and progenitor cells. These are evolutionary conserved pathways, involved in CSC maintenance. Targeting these pathways may be effective in eradicating CSCs and preventing chemotherapy or radiotherapy resistance.     

Tumor-initiating stem cells in liver cancer

It is widely accepted that cancer is a disease of stem cells. Definite evidence suggests that tumors harbor a small population of cancer stem cells (CSC) that both give rise to the bulk of the tumor and are tumorigenic in experimental models. Mounting evidence suggests that these cells are responsible for regrowth of a tumor following unsuccessful treatment and for the establishment of metastases. The concept of CSC has been demonstrated in several human cancers including leukemia, breast, prostate, lung, pancreas, colon and brain tumors. Recently, several studies have demonstrated that liver cancer, like other tumors, are derived from a small population of liver cancer stem/progenitor cells. Although still controversial, Liver CSC will likely become the most crucial target in the treatment of liver cancer, and a thorough understanding of its origin, molecular profile and particularly of how the Liver CSC differs from the normal stem cells, might allow it to be targeted selectively and eliminated, thus improving therapeutic outcome. In this review we will summarize the recent evidence for Liver CSC, the relationship between normal and liver stem cells, and the possibility that transformation of different cell types in the liver may generate different types of liver cancers.     

胃癌干细胞与微环境的研究进展

胃癌目前是仅次于肺癌的第二大致死性肿瘤,目前胃癌的发病机制还不是很清楚。近年来随着对肿瘤干细胞（CSC）和肿瘤生物学的研究,目前已经在多种实体瘤中发现CSC,但是由于胃癌干细胞缺乏特异性的标志物,因此还有很多空白待探究。虽然已发现一些胃癌干细胞表面标志物如CD44、CD133等,但缺乏特异性,仍需进一步探究更具特异性的胃癌干细胞标志物。CSC生存的环境在肿瘤的进程中也起重要的作用。文章对胃癌干细胞和微环境进行研究将有助于胃癌的诊断和治疗。     

Formation and regulation of the cancer stem cell niche

It is widely accepted that tumors contain cancer stem cells (CSC) possessing self‐renewal potential as well as the ability to generate numerous cancer cells. Cancer stem cells are resistant to conventional cancer therapy and have greater invasive and metastatic behavior. It has been suggested that blood vessels provide a niche that maintains stemness in normal organs. This role also extends to the field of cancer biology. Cancer stem cells have been isolated from leukemias and solid cancers. Identification of these cells and their niche is critical for identifying molecular targets in order to inhibit their growth and to destroy their niche. For this purpose, sorting of living CSC is required to monitor their presence in the presumptive niche to establish whether a CSC candidate actually shows malignant features. Based on and referring to analyses in normal tissues, molecules including nitric oxide, Wnt, neuropilin‐1, hepatocyte growth factor and others involved in the maintenance of CSC have been isolated. Stem cells might affect niche cells and niche cells produce stemness factors on such stimulation. Therefore, the niche might be flexible to support self‐renewal or differentiation of stem cells even in the same niche cells. (Cancer Sci 2012; 103: 1177–1181)     

Targeting breast cancer stem cells

The cancer stem cell (CSC) hypothesis postulates that tumors are maintained by a self‐renewing CSC population that is also capable of differentiating into non‐self‐renewing cell populations that constitute the bulk of the tumor. Although, the CSC hypothesis does not directly address the cell of origin of cancer, it is postulated that tissue‐resident stem or progenitor cells are the most common targets of transformation. Clinically, CSCs are predicted to mediate tumor recurrence after chemo‐ and radiation‐therapy due to the relative inability of these modalities to effectively target CSCs. If this is the case, then CSC must be efficiently targeted to achieve a true cure. Similarities between normal and malignant stem cells, at the levels of cell‐surface proteins, molecular pathways, cell cycle quiescence, and microRNA signaling present challenges in developing CSC‐specific therapeutics. Approaches to targeting CSCs include the development of agents targeting known stem cell regulatory pathways as well as unbiased high‐throughput siRNA or small molecule screening. Based on studies of pathways present in normal stem cells, recent work has identified potential “Achilles heals” of CSC, whereas unbiased screening provides opportunities to identify new pathways utilized by CSC as well as develop potential therapeutic agents. Here, we review both approaches and their potential to effectively target breast CSC.     

Cancer stem cells and the cellular hierarchy in haematological malignancies

Malignancies in the haematopoietic system seem to depend on a small subset of so-called cancer stem cells (CSC) for their continued growth and progression – this was first described as the “sleeper-feeder theory” for leukaemia. The leukaemia stem cell was the first of such subsets to be described although the origins of these cells have been difficult to dissect. Consequently, their biology is not fully elucidated, which also holds true for the normal-tissue counterparts.The stem cell concept describes stem cells to be of low frequency, self renewing and with multilineage potential based on phenomenology – a definition which may not hold strictly true for CSCs when studied in animals and humans in vivo and in vitro. Several studies have analysed the cellular hierarchy of the haematopoietic system by cell sorting of few and even single cells, tracking acquired genetic changes and performing transplantation model studies to document subsets within the differentiating hierarchy as potential CSC compartments.In leukaemia the CSC has been described in the bone marrow compartment of haematopoietic stem cells (HSC); however, in other bone marrow disorders like multiple myeloma it is likely that the cell of origin is a more differentiated cell, like post-germinal memory B cells or plasmablasts. Studies performed so far have even indicated that the genetic events may occur in different B cell subsets in accordance with the stepwise oncogenesis of the disease.Although our understanding of the nature and biology of these initiating cells remains unknown, the obvious existence of such cells has implications for understanding initial malignant transformation and disease metastasis or progression and, most important, the selection of individualised therapeutic strategies targeting the subsets harbouring the CSC function.In the present review on stem cells in haematological malignancies we have focused on two topics, first, describing the stem cell concept in health and disease, and its “phenomenology”, and second, describing the CSC compartments in leukaemia and multiple myeloma.     

Safely targeting cancer stem cells via selective catenin coactivator antagonism

Throughout our life, long‐lived somatic stem cells (SSC) regenerate adult tissues both during homeostatic processes and repair after injury. The role of aberrant regulation of SSC has also recently gained prominence in the field of cancer research. Following malignant transformation, so termed cancer stem cells (CSC), endowed with the same properties as SSC (i.e. the ability to both self‐renew and generate differentiated progenitors), play a major part in tumor initiation, therapy resistance and ultimately relapse. The same signaling pathways involved in regulating SSC maintenance are involved in the regulation of CSC. CSC exist in a wide array of tumor types, including leukemias, and brain, breast, prostate and colon tumors. Consequently, one of the key goals in cancer research over the past decade has been to develop therapeutic strategies to safely eliminate the CSC population without damaging the endogenous SSC population. A major hurdle to this goal lies in the identification of the key mechanisms that distinguish CSC from the normal endogenous tissue stem cells. This review will discuss the discovery of the specific CBP/catenin antagonist ICG‐001 and the ongoing clinical development of the second generation CBP/catenin antagonist PRI‐724. Importantly, specific CBP/catenin antagonists appear to have the ability to safely eliminate CSC by taking advantage of an intrinsic differential preference in the way SSC and CSC divide.     

小细胞肺癌干细胞信号通路的研究进展

小细胞肺癌是具有高度侵袭性的肺肿瘤,其主要临床特征是化疗有效率高但易在短时间内复发转移,这一特点可能与肿瘤干细胞的存在有关。肿瘤干细胞被认为是恶性肿瘤发生发展、耐药、复发及转移的根源。目前多认为肿瘤干细胞与正常干细胞有着相同的信号通路,如Hedgehog、Notch、Wnt等通路。本文就这几条信号通路在小细胞肺癌干细胞中所起的作用以及针对这几条信号通路治疗药物的研究进展和可能的信号通路交互作用等方面进行综述。     

上皮间质转化参与CSC生成及其调控

肿瘤组织中存在一小部分具有无限增殖、自我更新、分化潜能、放化疗耐受以及高致瘤能力等干细胞特性的肿瘤干细胞（cancer stem cells,CSC）,它们是肿瘤无法治愈并不断进展的重要原因。许多与诱导肿瘤细胞上皮间质转化（epithelial-to-mesenchymal transition,EMT）相关的信号通路与CSC 的生成及调控相关。本综述简要阐述了EMT 与CSC 生成及调控相关的研究进展。