抗胰腺癌干细胞单克隆抗体的筛选和鉴定

目的：从抗胰腺癌干细胞单抗库中筛选、鉴定识别胰腺癌干细胞的功能性单抗,为胰腺癌干细胞靶向治疗提供候选抗体药物。方法：无血清悬浮培养及PKH26染色确定胰腺癌HPAC细胞系中肿瘤干细胞的存在。流式细胞术检测HPAC的干细胞标志物CD133在球体细胞中的阳性比例,检测20株杂交瘤单抗在HPAC亲本和球体细胞中的阳性表达。双色荧光标记流式细胞术检测CD133和单抗在HPAC亲本和球体细胞中的共表达比例;无血清悬浮培养法观察单抗15E9对HPAC成球细胞自我更新的影响。CCK一8法检测单抗15E9对HPAC细胞增殖和耐药的影响。结果：HPAC细胞能在无血清培养基中存活、增殖并形成细胞球,成球率为4．8％±0．6％。HPAC球体细胞中CD133’细胞的比例较亲本细胞提高至11．6倍。20株候选杂交瘤单抗中有3株单抗能识别HPAC球体细胞中CD133’细胞,其中单抗15E9共染比例为3．5％,并能显著抑制HPAC细胞的成球,抑制率达到30．4％。单抗15E9联合吉西他滨能显著抑制HPAC球体细胞的增殖,联合组和对照组Ic50分别为30．8nmol／L和58．1nmol／L。结论：本研究成功筛选出1株杂交瘤单抗可以识别胰腺癌干细胞,并且可识别CD133＋的胰腺癌干细胞;体外功能显示该抗体具有抑制HPAC干细胞的自我更新能力,抗体干预后显著降低HPAC耐药能力,可能是潜在的胰腺癌干细胞的靶向治疗抗体药物。     

Mouse induced pluripotent stem cell microenvironment generates epithelial-mesenchymal transition in mouse Lewis lung cancer cells

Induced pluripotent stem (iPS) cells may be a powerful tool in regenerative medicine, but their potential tumorigenicity is a significant challenge for the clinical use of iPS cells. Previously, we succeeded in converting miPS cells into cancer stem cells (CSCs) under the conditions of tumor microenvironment. Both stem cells and tumor cells are profoundly influenced by bi-directional communication with their respective microenvironment, which dictates cell fate determination and behavior. The microenvironment derived from iPS cells has not been well studied. In this paper, we have investigated the effects of secreted factors from Nanog-mouse iPS (miPS) cells on mouse Lewis lung cancer (LLC) cells that are found in the conditioned media. The results demonstrated that miPS cells secrete factors that can convert the epithelia phenotype of LLC cells to a mesenchymal phenotype, and that can promote tumorigenisity, migration and invasion. Furthermore, LLC cells that have been exposed to miPS conditioned medium became resistant to apoptosis. These various biological effects suggest that the miPS microenvironment contain factors that can promote an epithelial-mesenchymal transition (EMT) through an active Snail-MMP axis or by suppressing differentiation in LLC cells.     

肿瘤干细胞的研究进展

近年来随着对肿瘤研究的不断深入,以及对干细胞了解的日益加深,越来越多的证据显示肿瘤与干细胞有着密切的关系,肿瘤可能是干细胞在异常微环境中差异分化的结果,并提出了肿瘤干细胞（tumor stem cell,TSC）的学说。本文综述了肿瘤干细胞的发现、特点,以及在肿瘤的诊断、治疗和预后判断中的作用,旨在为肿瘤发生发展研究及干细胞在肿瘤治疗方面的应用提供理论依据。     

The expression pattern of PFKFB3 enzyme distinguishes between induced-pluripotent stem cells and cancer stem cells

Induced pluripotent stem cells (iPS) have become crucial in medicine and biology. Several studies indicate their phenotypic similarities with cancer stem cells (CSCs) and a propensity to form tumors. Thus it is desirable to identify a trait which differentiates iPS populations and CSCs. Searching for such a feature, in this work we compare the restriction (R) point-governed regulation of cell cycle progression in different cell types (iPS, cancer, CSC and normal cells) based on the expression profile of 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase3 (PFKFB3) and phosphofructokinase (PFK1). Our study reveals that PFKFB3 and PFK1 expression allows discrimination between iPS and CSCs. Moreover, cancer and iPS cells, when cultured under hypoxic conditions, alter their expression level of PFKFB3 and PFK1 to resemble those in CSCs. We also observed cell type-related differences in response to inhibition of PFKFB3. This possibility to distinguish CSC from iPS cells or non-stem cancer cells by PFKB3 and PFK1 expression improves the outlook for clinical application of stem cell-based therapies and for more precise detection of CSCs.     

肿瘤转移干细胞与抗转移策略

肿瘤干细胞（cancer stem cell,CSC）能自我更新,分化形成异质性的肿瘤子代细胞群,是肿瘤复发与转移的主要原因。肿瘤转移干细胞（metastatic cancer stem cell,MCSC）具有CSC特性,同时伴有转移能力。肿瘤转移既发生于肿瘤晚期,也发生于早期。MCSC在起源、上皮-间质转变（epithelial-mesenchymal transition,EMT）、间质-上皮转变（mesenchymal-epithelial transition,MET）和靶器官小生境（niche）等方面与CSC不同,因而MCSC是肿瘤转移的基础。杀灭CSC、阻断EMT和MET、抑制MCSC微血管黏附和阻断MCSC依赖的小生境可构建抗肿瘤转移的治疗策略。本文主要介绍MCSC的可能来源,MCSC的生物学特性,MCSC近期研究中可能取得的突破,以及针对MCSC的抗转移策略,为肿瘤转移机制研究和抗转移研究提供参考。     

胰腺肿瘤干细胞研究新进展

胰腺肿瘤尤其是胰腺导管腺癌的恶性程度高,转移性强,预后差。以往研究表明肿瘤干细胞(cancer stem cells,CSC)在胰腺肿瘤的发生、发展过程中起重要作用,深入了解胰腺肿瘤的发病机制将有助于针对性治疗。在胰腺发育过程中,复杂的信号通路和转录因子决定了其前体细胞分化方向,在胰腺发生恶变过程中,这些因素又参与其中,因而往往可以作为追溯CSC的标志。一些研究也应用特定蛋白来筛选胰腺CSC。现就胰腺CSC的来源、鉴定和靶向治疗进行综述。     

Claudin7-dependent exosome-promoted reprogramming of nonmetastasizing tumor cells

Claudin7 (cld7) is a cancer-initiating cell (CIC) marker in gastrointestinal tumors, a cld7-knockdown (kd) being accompanied by loss of tumor progression. Tumor exosomes (TEX) restoring CIC activities, we explored the contribution of cld7. This became particularly interesting, as tight junction (TJ)- and glycolipid-enriched membrane domain (GEM)-derived cld7 is recruited into distinct TEX. TEXs were derived from CIC or cld7kd cells of a rat pancreatic and a human colon cancer line. TEX derived from pancreatic cancer cld7kd cells rescued with palmitoylation site-deficient cld7 (cld7mP) allowed selectively evaluating the contribution of GEM-derived TEX, only palmitoylated cld7 being integrated into GEM. Cld7 CIC-TEX promoted tumor cell dissemination and metastatic growth without a major impact on proliferation, apoptosis resistance and epithelial–mesenchymal transition. Instead, migration, invasion and (lymph)angiogenesis were strongly supported, only migration being selectively fostered by GEM-derived cld7 TEX. CIC-TEX coculture of cld7kd cells uncovered significant changes in the cld7kd cell protein and miRNA profiles. However, changes did not correspond to the CIC-TEX profile, CIC-TEX rather initiating integrin, protease and RTK, particularly lymphangiogenic receptor activation. CIC-TEX preferentially rescuing cld7kd-associated defects in signal transduction was backed up by an RTK inhibitor neutralizing the impact of CIC-TEX on tumor progression. In conclusion, cld7 contributes to selective steps of the metastatic cascade. Defects of cld7kd and cld7mP cells in migration, invasion and (lymph)angiogenesis are effaced by CIC-TEX that act by signaling cascade activation. Accordingly, RTK inhibitors are an efficient therapeutic defeating CIC-TEX.     

Therapeutic strategies targeting cancer stem cells

Increasing studies have demonstrated a small proportion of cancer stem cells (CSCs) exist in the cancer cell population. CSCs have powerful self-renewal capacity and tumor-initiating ability and are resistant to chemotherapy and radiation. Conventional anticancer therapies kill the rapidly proliferating bulk cancer cells but spare the relatively quiescent CSCs, which cause cancer recurrence. So it is necessary to develop therapeutic strategies acting specifically on CSCs. In recent years, studies have shown that therapeutic agents such as metformin, salinomycin, DECA-14, rapamycin, oncostatin M (OSM), some natural compounds, oncolytic viruses, microRNAs, cell signaling pathway inhibitors, TNF-related apoptosis inducing ligand (TRAIL), interferon (IFN), telomerase inhibitors, all-trans retinoic acid (ATRA) and monoclonal antibodies can suppress the self-renewal of CSCs in vitro and in vivo. A combination of these agents and conventional chemotherapy drugs can significantly inhibit tumor growth, metastasis and recurrence. These strategies targeting CSCs may bring new hopes to cancer therapy.     

Lipid metabolism of cancer stem cells

Cancer stem cells (CSCs), also termed cancer-initiating cells, are a special subset of cells with high self-replicating and self-renewing abilities that can differentiate into various cell types under certain conditions. A number of studies have demonstrated that CSCs have distinct metabolic properties. The reprogramming of energy metabolism enables CSCs to meet the needs of self-renewal and stemness maintenance. Increasing evidence supports the view that alterations in lipid metabolism, including an increase in fatty acid (FA) uptake, de novo lipogenesis, formation of lipid droplets and mitochondrial FA oxidation, are involved in CSC regulation. In the present review, the metabolic characteristics of CSCs, particularly in lipid metabolism, were summarized. In addition, the potential mechanisms of CSC lipid metabolism in treatment resistance were discussed. Given their significance in cancer biology, targeting CSC metabolism may serve an important role in future cancer treatment.     

多发性内分泌腺瘤病1型患者血液细胞来源特异性诱导多能干细胞的建立

目的:建立多发性内分泌腺瘤病1型(multiple endocrine neoplasia 1,MEN1)患者血液细胞来源的特异性诱导多能干细胞(induced pluripotent stem cells,iPSCs)模型.方法:将表达Oct4、Sox2、Lin28、L-Myc和Klf4转录因子的oriP/EBNA1附着体电转染MEN1患者血液细胞使其重编程获得iPSCs,并通过碱性磷酸酶染色、核型鉴定、基因测序、RT-PCR反应、畸胎瘤形成实验及类胚体形成实验检测其特性.结果:获得的iPSCs碱性磷酸酶染色呈阳性,核型正常,测序结果显示在其第9号外显子存在c.1288 G>T位点突变,表达干细胞多能性基因Sox2、Oct4、Nanog和Klf4和Lin28,体内畸胎瘤形成实验可分化为内、中、外三胚层细胞,体外可形成类胚体.结论:成功获得携带第9号外显子c.1288 G>T位点突变的MEN1患者血液细胞来源的特异性iPSCs,为后续机制研究奠定基础.     

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 in human gastrointestinal cancer

Cancer stem cells (CSCs) are thought to be responsible for tumor initiation, drug and radiation resistance, invasive growth, metastasis, and tumor relapse, which are the main causes of cancer‐related deaths. Gastrointestinal cancers are the most common malignancies and still the most frequent cause of cancer‐related mortality worldwide. Because gastrointestinal CSCs are also thought to be resistant to conventional therapies, an effective and novel cancer treatment is imperative. The first reported CSCs in a gastrointestinal tumor were found in colorectal cancer in 2007. Subsequently, CSCs were reported in other gastrointestinal cancers, such as esophagus, stomach, liver, and pancreas. Specific phenotypes could be used to distinguish CSCs from non‐CSCs. For example, gastrointestinal CSCs express unique surface markers, exist in a side‐population fraction, show high aldehyde dehydrogenase‐1 activity, form tumorspheres when cultured in non‐adherent conditions, and demonstrate high tumorigenic potential in immunocompromised mice. The signal transduction pathways in gastrointestinal CSCs are similar to those involved in normal embryonic development. Moreover, CSCs are modified by the aberrant expression of several microRNAs. Thus, it is very difficult to target gastrointestinal CSCs. This review focuses on the current research on gastrointestinal CSCs and future strategies to abolish the gastrointestinal CSC phenotype.     

以肿瘤干细胞为靶的免疫治疗

肿瘤干细胞(cancer stem cell,CSC)是肿瘤发生和转移的种子细胞,CSC具有自我更新、增殖和不完全分化的能力。CSC对化疗/放疗的抵抗以及免疫逃逸成为肿瘤复发的根源,要提高肿瘤治愈率必须彻底清除CSC。认识CSC的标记特征和"干性"调节关键分子才能有效和特异地攻击CSC。免疫治疗具有抗原识别的靶向性和时空效应性,是以CSC为靶的治疗的基础;以单克隆抗体和致敏的免疫细胞为主要治疗技术的免疫治疗清除CSC具有可实践性和挑战性。     

前列腺癌干细胞与去势抵抗性前列腺癌放射性耐受的研究进展

前列腺癌经过去势治疗后有进展为去势抵抗性前列腺癌的可能。去势抵抗性前列腺癌对临床医生最大的挑战为其治疗抵抗特性。针对放疗耐受,相关研究认为与前列腺癌干细胞及前列腺癌干细胞相关miRNA相关。下文从去势抵抗性前列腺癌进展机制、前列腺癌干细胞及前列腺癌干细胞相关miRNA等方面介绍去势抵抗性前列腺癌放射性耐受的研究进展。     

肿瘤干细胞的临床意义

肿瘤干细胞(cancer stem cell, CSC)是近年来在许多肿瘤组织中发现的一类特殊干细胞。肿瘤干细胞具有自我更新和分化的能力,可以通过不断分化肿瘤细胞使新的肿瘤产生;肿瘤干细胞具有很强的耐药性和放射抗拒,这可以用来解释肿瘤的复发和转移。肿瘤干细胞可用于对肿瘤的诊断和治疗：通过对肿瘤干细胞标志物的鉴定可实现对一些肿瘤的早期诊断;一些新的治疗手段则通过作用于肿瘤干细胞的信号转导途径、表面标记和其生存的微环境,以及诱导其分化,从而达到靶向治疗肿瘤的目的。深入研究肿瘤干细胞的耐药性以及确定更多的肿瘤干细胞标志物,可为肿瘤治疗提供新途径。     

Alpha-fetoprotein-producing pancreatic cancer cells possess cancer stem cell characteristics

We aimed to demonstrate the existence of cancer stem cells in human pancreatic cancer, and to clarify that they are alpha-fetoprotein (AFP) producing cells. Six cell lines derived from human pancreatic cancers were examined, and AsPC-1 and PANC-1 were noted to express AFP. Single cell culture assays and xenotransplantation revealed that the AFP-producing cells had the capacity for self-renewal and differentiation, and that these cells were tumorigenic. Furthermore, they were resistant to anti-cancer agents. The ABCA12 transporter was expressed in the AFP-producing cells at a level more than twice as high as that in the non-AFP-producing cells. The AFP-producing cells were shown to be putative pancreatic cancer stem cells. Furthermore, the expression of ABCA12 appears to be associated with drug resistance.     

SOX2 is required to maintain cancer stem cells in ovarian cancer

Ovarian cancer cells can form spheroids under serum‐free suspension culture conditions. The spheroids, which are enriched in cancer stem cells, can result in tumor dissemination and relapse. To identify new targetable molecules in ovarian cancer spheroids, we investigated the differential expression of genes in spheroids compared with that under monolayer culture conditions by qPCR microarray. We identified that SOX2 is overexpressed in spheroids. We then proved that SOX2 expression was increased in successive spheroid generations. Besides, knockdown of SOX2 expression in SKOV3 or HO8910 ovarian cancer spheroid cells decreased spheroid formation, cell proliferation, cell migration, resistance to Cisplatin treatment, tumorigenicity, and the expression of stemness‐related genes and epithelial to mesenchymal transition‐related genes, whereas overexpression of SOX2 in SKOV3 or HO8910 ovarian cancer cells showed the opposite effects. In addition, we found that SOX2 expression was closely associated with chemo‐resistance and poor prognosis in EOC patients. These results strongly suggest that SOX2 is required to maintain cancer stem cells in ovarian cancer. Targeting SOX2 in ovarian cancer may be therapeutically beneficial.     

Complexity of cancer stem cells

Heterogeneity of tumor tissue has been accounted for in recent years by a hierarchy‐based model in which cancer stem cells (CSCs) have the ability both to self‐renew and to give rise to differentiated tumor cells and are responsible for the overall organization of a tumor. Research into CSCs has progressed rapidly and concomitantly with recent advances in the biology of normal tissue stem cells, resulting in the identification of CSCs in a wide range of human tumors. Studies of mouse models of human cancer have provided further insight into the characteristics of CSCs as well as a basis for the development of novel therapies targeted to these cells. However, recent studies have revealed complexities, such as plasticity of stem cell properties and clonal diversity of CSCs, in certain tumor types that have led to revision of the original CSC model. In this review, we summarize the history of the discovery and characterization of CSCs, as well as address recent advances that have revealed the complexity of these cells and their therapeutic implications.