CD133与肿瘤干细胞研究进展

越来越多的证据表明肿瘤中存在肿瘤干细胞(cancer stem cells),并且其与肿瘤的增殖、转移、复发和对放化疗不敏感关系密切.因此,肿瘤治疗应当针对肿瘤干细胞,通过特异表面标记分选肿瘤干细胞是研究其生长特点的前提.近年来,CD133为研究最多的在于细胞(stem cell)和多种组织肿瘤干细胞表面独立表达的特异标记分子.通过CD133可以分选干细胞、前体细胞和肿瘤干细胞.众多研究表明,CD133~+肿瘤细胞与肿瘤的自我更新、分化潜能、信号传导调控、药物耐受、复发和预后等均有相关性.CD133~+细胞有望在干细胞相关疾病的治疗和肿瘤靶向治疗中发挥巨大作用.     

Clinicopathological Significance of CD133 and ALDH1 Cancer Stem Cell Marker Expression in Invasive Ductal Breast Carcinoma

Background: Biomarkers in breast neoplasms provide invaluable information regarding prognosis and help determining the optimal treatment. We investigated the possible correlation between cancer stem cell (CSC) markers (CD133, and ALDH1) in invasive ductal breast carcinomas with some clinicopathological parameters. Aim: To assess the correlation between expression of cancer stem cell (CSC) markers (CD133, and ALDH1) and clinicopathological parameters of invasive ductal breast carcinomas. Materials and Methods: Immunohistochemical analysis of CD133 and ALDH1 was performed on a series of 120 modified radical mastectomy (MRM) specimens diagnosed as invasive ductal breast carcinoma. Results: Expression of both CD133 and ALDH1 was significantly changed and related to tumor size, tumor stage (TNM), and lymph node metastasis. A negative correlation between CD133 and ALDH1 was found. Conclusions: Detecting the expression of CD133 and ALDH1 in invasive ductal breast carcinomas may be of help in more accurately predicting the aggressive properties and determining the optimal treatment.     

肿瘤干细胞标志物CD133、CD44、OCT-4在小细胞肺癌中的表达及其临床意义

目的：探讨肿瘤干细胞标志物CD133、CD44、OCT-4与小细胞肺癌临床病理特征之间的相关性及临床意义。方法应用免疫荧光技术检测小细胞肺癌细胞株NCI-H82中肿瘤干细胞标志物CD133、CD44、OCT-4的表达;同时应用免疫组织化学法检测79例小细胞肺癌组织中CD133、CD44、OCT-4的表达。结果在小细胞肺癌细胞株NCI-H82中,CD133和CD 44的荧光信号为阳性表达,OCT-4的荧光信号为阴性表达。小细胞肺癌组织中CD133和CD44表达与肿瘤直径、淋巴结转移和临床分期相关,差异具有统计学意义（P＜0.05）。小细胞肺癌组织中OCT-4为阴性表达。结论 CD133和CD44可能是小细胞肺癌肿瘤干细胞的标志物,对小细胞肺癌的诊断和治疗有一定的临床意义。     

Cancer stem/progenitor cells are highly enriched in CD133+CD44+ population in hepatocellular carcinoma

Both our previous study and other reports have suggested that CD133, originally classified as a hematopoietic stem cell marker, could be used for enrichment of cancer stem cells (CSCs) in human hepatocellular carcinoma (HCC). It was also noted that not all of CD133⁺ cells were representative of CSCs. Further identification and characterization of CSCs or tumor‐initiating cells in HCC are necessary to better understand hepatocarcinogenesis. In present study, we demonstrated that CSC phenotype could be precisely defined by co‐expression of CD133 and CD44 cell surface markers. CD133⁺CD44⁺ HCC cells showed stem cell properties, including extensive proliferation, self‐renewal, and differentiation into the bulk of cancer cells. In vivo xenograft experiments revealed that, actually, the highly tumorigenic capacity of CD133⁺ cells as previously described was primarily attributed to CD133⁺CD44⁺ cell subpopulation, instead of their CD133⁺CD44^? counterparts. Moreover, cells double‐positive for CD133 and CD44 exhibited preferential expression of some stem cell‐associated genes and were more resistant to chemotherapeutic agents due to the upregulation of ATP‐binding cassette (ABC) superfamily transporters, including ABCB1, ABCC1, and ABCG2, further supporting these cells as HCC cell origin. Our findings suggest that CD133⁺CD44⁺ cells might represent true cancer stem/progenitor cells in HCC, which could allow a better understanding of HCC initiation and progression, as well as establish a precise target for the development of more effective therapies.     

肝细胞性肝癌组织CD133+细胞肿瘤干细胞特性的研究

目的 越来越多的研究表明,肝癌细胞系中能检测到肿瘤干细胞(cancer stem cells,CSCs)的存在.本研究旨在探讨从肝细胞性肝癌(hepatocellular carcinoma,HCC)组织样本中分离获得的CD133+细胞是否具有CSCs特性.方法 将2014-02-01-2015-06-30广西医科大学附属肿瘤医院肝胆外科25例手术获得的新鲜HCC组织和对应癌旁组织,采用酶消化法分别消化成单个肝癌细胞和单个肝细胞,利用流式细胞术检测部分单个肝癌细胞和单个肝细胞CD133的表达率.用剩余的单个肝癌细胞进行原代培养,流式细胞术将培养获得的肝癌细胞分选为CD133+和CD133-细胞,通过平板克隆形成实验、肿瘤球形成实验和裸鼠移植瘤形成实验对比分析这两组细胞的CSCs特性.结果 25例HCC组织中CD133的表达率为3.8％～8.3％,平均值为(5.8±1.6)％,而癌旁组织CD133的表达率为0.1％～0.4％,平均值为(0.2±0.1)％,两者比较差异有统计学意义,t=17.12,P＜0.001.CD133+和CD133-细胞的平均克隆率分别为(25.2±0.8)％和(7.6±0.8)％,两者比较差异有统计学意义,t=81.95,P＜0.001.CD133+和CD133-细胞的平均成球率分别为(20.3±0.6)％和(12.5±1.4)％,两者比较差异有统计学意义,t=68.17,P＜0.001.CD133+细胞的裸鼠移植瘤形成能力明显高于CD133-细胞.结论 从HCC组织样本中分离获得的CD133+细胞具有明显的CSCs特性.     

CD133 negative glioma cells form tumors in nude rats and give rise to CD133 positive cells

CD133 is a cell surface marker expressed on progenitors of haematopoietic and endothelial cell lineages. Moreover, several studies have identified CD133 as a marker of brain tumor-initiating cells. In this study, human glioblastoma multiforme biopsies were engrafted intracerebrally into nude rats. The resulting tumors were serially passaged in vivo, and monitored by magnetic resonance imaging. CD133 expression was analyzed at various passages. Tumors initiated directly from the biopsies expressed little or no CD133, and showed no contrast enhancement suggesting an intact blood-brain barrier. During passaging, the tumors gradually displayed more contrast enhancement, increased angiogenesis and a shorter survival. Real-time qPCR and immunoblots showed that this was accompanied by increased CD133 expression. Primary biopsy spheroids and xenograft tumors were subsequently dissociated and flow sorted into CD133 negative and CD133 positive cell populations. Both populations incorporated BrdU in cell culture, and expressed the neural precursor marker nestin. Notably, CD133 negative cells derived from 6 different patients were tumorgenic when implanted into the rat brains. For 3 of these patients, analysis showed that the resulting tumors contained CD133 positive cells. In conclusion, we show that CD133 negative glioma cells are tumorgenic in nude rats, and that CD133 positive cells can be obtained from these tumors. Upon passaging of the tumors in vivo, CD133 expression is upregulated, coinciding with the onset of angiogenesis and a shorter survival. Thus, our findings do not suggest that CD133 expression is required for brain tumor initiation, but that it may be involved during brain tumor progression.     

RNA aptamers targeting cancer stem cell marker CD133

The monoclonal antibody against the AC133 epitope of CD133 has been widely used as a cell surface marker of cancer stem cells in several different cancer types. Here, we describe the isolation and characterisation of two RNA aptamers, including the smallest described 15 nucleotide RNA aptamer, which specifically recognise the AC133 epitope and the CD133 protein with high sensitivity. As well, both these aptamers show superior tumour penetration and retention when compared to the AC133 antibody in a 3-D tumour sphere model. These novel CD133 aptamers will aid future development of cancer stem cell targeted therapeutics and molecular imaging.     

下调CD133表达对肝癌干细胞上皮间质化和侵袭能力影响及机制探讨

目的 肿瘤干细胞是肿瘤复发和转移的原因.探讨CD133基因RNA干扰(RNA interference,RNAi)的重组质粒,对人肝癌细胞株MHCC-H的CD133基因表达、上皮间质化和侵袭能力的影响.方法 通过免疫磁珠分选MHCC-H细胞中的CD133阳性细胞,设计并合成特异性靶向CD133的小分子干扰RNA(small interfering RNA,siRNA)片段,并构建pSuper retro GFP-neo-siRNA-CD133表达质粒,将其转入MHCC-H-CD133+细胞,并设空白对照组、阳性对照组.通过G418筛选出稳定株.通过粘附实验、Boyden小室实验和软琼脂克隆形成实验观察各细胞株侵袭能力的变化.采用明胶酶法测定肝癌细胞的基质金属蛋白酶-2(matrix metalloproteinase-2,MMP 2)和MMP-9的含量,蛋白质印迹法检测上皮间质化相关基因的变化.结果 通过免疫磁珠分选后的MHCC-H细胞中CD133表达率为83.5％.qRT-PCR结果显示,shCD133组相对空白对照组的CD133表达量下降了80％,P＜0.05.蛋白质印迹法检测结果显示,shCD133组的CD133表达明显下降,约为空白对照组的12％和shNC组的10％,均P＜0.05.shCD133组的粘附能力为86.9±12.4,较空白对照组的568.5±53.2和shNC组的538.8±35.6明显下降,P＜0.05.Boyden小室实验发现,shCD133组穿膜细胞数为(80.6±11.4)个,较空白对照组的(228.5±33.2)个和shNC组的(230.8±32.9)个明显减少,P＜0.05.软琼脂克隆形成率的检测发现,shCD133的细胞克隆形成(60±5)个,比空白对照组的(178±23)个和shNC组的(168±25)个明显下降,P＜0.05.明胶酶法检测发现,shCD133组MMP-2和MMP-9相对活性为0.4±0.14和0.6±0.16,较shNC组的1.03±0.19和1.3±0.16明显下降,P＜0.05.蛋白质印迹法检测结果表明,shCD133组N-cadherin蛋白表达为36.3±4.5,Snail为53.6±6.7,Slug为41.63±5.6,Twist为39.4±3.9,均明显低于空白对照组的87.6±8.6、80.6±7.5、81.9±9.2和83.9±9.1,也明显低于shNC组的89.4±9.6、83.5±8.9、85.1±8.7和87.6±9.3,均P＜0.05;而shCD133组E-cadherin表达为88.4±9.2,较空白对照组的57.6±8.7和shNC组的53.9±8.9明显上调,P＜0.05.结论 沉默MHCC-H细胞CD133基因的表达能有效抑制其上皮间质化和侵袭能力,CD133基因可能成为肝癌基因治疗的有效靶点.     

Lenti-TK介导间充质干细胞对鼻咽癌CD133+干细胞的靶向迁移及杀伤作用

目的： 观察慢病毒-胸苷激酶（lentivirus-thymidine kinase,Lenti-TK)/间充质干细胞(mesenchymal stem cell,MSC）对鼻咽癌CD133+干细胞的靶向迁移及杀伤作用。 方法： 构建包含TK基因的重组慢病毒表达载体Lenti-TK,感染MSC后得到Lenti-TK-MSC,RT-PCR及Western blotting检测Lenti-TK-MSC中HA-TK的表达。免疫磁珠法从鼻咽癌5-8F细胞中分选CD133+细胞;Transwell小室迁移实验检测Lenti-TK-MSC对CD133+5-8F细胞的趋向性;Lenti-TK-MSC联合更昔洛韦（ganciclovir,Lenti-TK-MSC/GCV）与CD133+5-8F细胞共培养,CCK-8试剂盒检测其对细胞的杀伤作用和旁观者效应。 结果： 成功构建重组慢病毒载体Lenti-TK,其滴度为1×108UT/ml,Lenti-TK（MOI=50）感染MSC 72 h时,感染效率达（95.1±01）%。Lenti-TK-MSC迁移至CD133+5-8F细胞组的细胞数明显多于CD133-5-8F细胞组、未分选5-8F细胞组\[（83.0±8.7） vs （29.6±53）、（38.3±5.2）,P=0.000\]。Lenti-TK-MSC/GCV处理组与单独GCV处理组、Lenti-TK-MSC/GCV条件培养液（即Lenti-TK-MSC加入1 mg/L GCV培养48 h的培养上清）处理组相比,CD133+5-8F细胞的存活率明显降低\[（37.2±2.3）% vs （98.5±3.1）%、（83.8±34）%,P=0.000\]。Lenti-TK-MSC数量达到混合细胞总数（Lenti-TK-MSC和CD133+5-8F细胞)的20%时,CD133+5-8F细胞存活率为（68.2±2.3）%,表现出明显的旁观者杀伤效应。 结论： Lenti-TK感染后MSC对鼻咽癌CD133+5-8F细胞具有靶向迁移及杀伤作用。     

Expression patterns of cancer stem cell markers ALDH1 and CD133 correlate with a high risk of malignant transformation of oral leukoplakia

Molecular markers for predicting oral cancer development in premalignant oral leukoplakia (OL) are urgently needed. The objective of this study was to examine the expression patterns of cancer stem cell markers ALDH1 and CD133 in samples from patients with OL, and determine their prognostic values for subsequent development of oral cancer. Immunohistochemistry for ALDH1 and CD133 was performed in samples from a cohort of 141 patients with biopsy‐proven OL who received a mean follow‐up of 5.5 years. Patient clinicopathologic and follow‐up data were analyzed. Expression of ALDH1 and CD133 was observed in 54 (38.3%) and 32 (22.7%) of 141 patients with OL, respectively. Kaplan–Meier analysis showed that 48.1% patients with ALDH1‐positivity developed oral cancer compared with 12.6% those with ALDH1‐negativity (p < 0.001). Meanwhile, 59.4% patients with CD133‐positivity developed oral cancer compared with 16.5% those with CD133‐negativity (p < 0.001). Multivariate analysis revealed that ALDH1 and CD133 expression was associated with 4.17‐fold [95% confidence interval (CI), 1.96–8.90; p < 0.001] and 2.86‐fold (95% CI, 1.48‐5.55; p = 0.002) increased risk of OL transformation, respectively. Collectively, these data demonstrated for the first time that the expression of ALDH1 and CD133 correlated with malignant transformation in a large series of patients with OL who received a long‐term follow‐up, which suggests that they may serve as predictors to identify OL with a high risk of oral cancer development.     

CD133+ liver cancer stem cells modulate radioresistance in human hepatocellular carcinoma

CD133 is a cancer stem-cell (CSC) marker associated with radioresistance and chemoresistance in various cancers. In the present study, CD133-expressing liver cancer cells following radiation exposure showed higher activation of MAPK/PI3K signaling pathway and reduction in reactive oxygen species levels compared to CD133⁻ cells. The in vivo study with a xenograft model showed increased tumor formation in irradiated CD133⁺ cell-injected nude mice compared to the CD133⁻ group, suggesting that CD133 contributes to radioresistance in HCC. Therefore, CD133-expressing liver cancer cells have anti-apoptotic and radioresistance properties that may be useful to improve anti-cancer treatments, including chemotherapy/radiotherapy of HCC.     

肿瘤干细胞标志物CD133在胃癌中的表达及其临床意义

目的：探讨CD133在胃癌组织中的表达及其临床意义。方法：采用半定量逆转录聚合酶链反应（RT—PCR）检测38例手术切除的胃癌原发组织、癌旁正常胃粘膜组织和其中8例肝转移灶组织中CD133mRNA的表达,免疫组织化学方法检测肿瘤组织中CD133蛋白的表达情况,分析CD133的表达与临床病理参数的关系。结果：胃癌癌旁、原发、转移组织中CD133mRNA的灰度相对值分别为0．189±0．149、0．3054-0．118和0．359±0．139,癌旁与原发组织之间差异有统计学意义（P〈0．01）,原发与转移组织之间差异无统计学意义（P〉0．05）。免疫组化检测肿瘤组织中CD133蛋白表达,阳性细胞稀少。原发组织CD133mRNA的表达与肿瘤大小和Ki-67表达相关（P〈0．05）,与性别、年龄、浸润深度、淋巴结转移分期、TNM分期、组织分化程度及p53表达均无关（P〉0．05）。结论：CD133的表达与胃癌的发生有关,与转移的关系有待进一步研究,可能在胃癌的诊断中起一定的作用。     

Prognostic impact of the expression of putative cancer stem cell markers CD133, CD166, CD44s, EpCAM, and ALDH1 in colorectal cancer

Background:

The aim of this study was to elucidate the prognostic impact of putative cancer stem cell markers CD133, CD166, CD44s, EpCAM, and aldehyde dehydrogenase-1 (ALDH1) in colorectal cancer.

Methods:

A tissue microarray of 1420 primary colorectal cancers and 57 normal mucosa samples was immunostained for CD133, CD166, CD44s, EpCAM, and ALDH1 in addition to 101 corresponding whole tissue sections. Invasive potential of three colorectal cancer cell lines was tested.

Results:

Differences between normal tissue and cancer were observed for all markers (P<0.001). Loss of membranous CD166 and CD44s were linked to higher pT (P=0.002, P=0.014), pN (P=0.004, P=0.002), an infiltrating growth pattern (P<0.001, P=0.002), and worse survival (P=0.015, P=0.019) in univariate analysis only. Loss of membranous EpCAM expression was also linked to higher pN (P=0.023) and infiltrating growth pattern (P=0.005). The CD44s, CD166, and EpCAM expression were lost towards the invasive front. The CD44−/CD166− cells from three colorectal cancer cell lines exhibited significantly higher invasive potential in vitro than their positive counterparts.

Conclusions:

Loss, rather than overexpression, of membranous CD44s, CD166, and EpCAM is linked to tumour progression. This supports the notion that the membranous evaluation of these proteins assessed by immunohistochemistry may be representative of their cell adhesion rather than their intra-cellular functions.     

Active glycolytic metabolism in CD133(+) hepatocellular cancer stem cells: regulation by MIR-122

Although altered metabolic pathway is an important diagnostic maker and therapeutic target in cancer, it is poorly understood in cancer stem cells (CSCs). Here we show that the CD133 (+) hepatocellular CSCs have distinct metabolic properties, characterized by more active glycolysis over oxidative phosphorylation, compared to the CD133 (−) cells. Inhibition of PDK4 and LDHA markedly suppresses CD133 (+) stemness characteristics and overcome resistance to sorafenib (current chemotherapeutic agent for hepatocellular cancer). Addition of glucose or lactate to CD133 (−) cells promotes CSC phenotypes, as evidenced by increased CD133 (+) cell population, elevated stemness gene expression and enhanced spheroid formation. Furthermore, the liver-specific miRNA, miR-122, inhibits CSC phenotypes by regulating glycolysis through targeting PDK4. Our findings suggest that enhanced glycolysis is associated with CD133 (+) stem-like characteristics and that metabolic reprogramming through miR-122 or PDK4 may represent a novel therapeutic approach for the treatment of hepatocellular cancer.     

CD133-positive tumor cell content is a predictor of early recurrence in colorectal cancer

Background

The aims of this study were to demonstrate the tumorigenicity of CD133+ colon cancer cells in vitro, analyze the correlations between spheroid formation and clinicopathologic variables, and screen for overexpressed genes in CD133+ colon cancer stem cells. Moreover, the aim of this study was to establish a living tumor tissue bank using surgically resected specimens.

Methods

Using LoVo cell line, we isolated CD133+ cells and performed clonogenic assay and animal experiment to test tumorigenicity of CD133+ cells. Twenty-nine surgical samples were freshly collected from 27 patients who received curative or palliative surgery, and the samples were mechanically and enzymatically dissociated into single cells.

Results

We confirmed the enhanced tumorigenicity of CD133+ cells isolated from LoVo cell line both in vitro and in vivo. Of these 29 samples, 8 (28%) contained >3% CD133+ cells. Sphere formation was significantly higher in samples from patients with lymphatic invasion than in those without lymphatic invasion [54.5% (6/11) vs. 12.5% (2/16); P=0.033] and in samples containing >3% of CD133+ cells than in those containing ≤3% of CD133+ cells [36.4% (4/11) vs. 0% (0/16); P=0.019].

Conclusions

These findings indicate that CD133 is a valid marker for identifying cancer stem cells from fresh surgically resected colorectal cancer tissues. Furthermore, we successfully established a living tumor tissue bank using surgically resected colorectal tissues with a viability of >70%.     

上皮源性卵巢癌干细胞的研究进展

肿瘤干细胞(cancer stem cells,CSCs)是肿瘤组织内具有自我更新能力以及无限增殖和多向分化潜能的一群细胞,对化疗药物耐受.卵巢癌干细胞(epithelial ovarian cancer stem cells,EOCSCs)在卵巢癌的发生发展、侵袭转移和耐药复发过程中都起到了重要作用.传统的肿瘤细胞减灭术联合顺铂、紫杉醇全身化疗对减小肿瘤体积,缓解临床症状具有一定的作用,但治疗后残留的EOCSCs能够短时间内重建肿瘤组织,是卵巢癌复发和难治的根本原因.深入了解EOCSCs的生物学特性,探索EOCSCs的发生发展机制,研究针对EOCSCs的靶向治疗药物,是抗肿瘤治疗的关键.     

肝癌细胞系Huh-7中CD133阳性细胞亚群的分离及其特性的研究

目的：研究CD133在人肝癌细胞系Huh-7中的表达,初步探讨肝癌中CD133阳性细胞亚群的干细胞特性。方法：流式细胞荧光激活分选技术纯化肝癌细胞系Huh-7中CD133肿瘤细胞,体外培养并观察其增殖、体内成瘤及分化能力。结果i流式细胞仪检测肝癌细胞系Huh-7中有62．3％的细胞CD133呈阳性表达,流式细胞荧光激活分选的CD133肿瘤细胞在无血清培养基中第3、5、7d的吸光度（OD值）分别为0．310、0．362、0．564,均高于相同条件下未分选细胞和CD133阴性细胞;CD133阳性细胞亚群成瘤能力明显强于阴性细胞亚群;CD133阳性细胞亚群在培养体系中的比例逐日下降,至培养的第8天,由第1天的92．3％下降至61．4％。结论：肝癌细胞系Huh-7中CD133阳性细胞亚群比其它细胞亚群具有较强增殖、成瘤和分化能力,是具有肝癌干细胞特性的细胞亚群。     

CD133 expression in circulating tumor cells from breast cancer patients: Potential role in resistance to chemotherapy

CD133 has been associated with cell properties such as self renewal, migration and vasculogenic mimicry, potentially involved in generation of circulating tumor cells (CTCs). We characterized CD133 expression in CTCs of 98 nometastatic breast cancer (BC) patients. CTCs were isolated by immunomagnetic techniques using magnetic beads labeled with a multicytokeratin(CK)‐specific antibody (CK3‐11D5) and CTCs and CD133 detection through immunocytochemical methods. CK⁺/CD133⁺ CTCs were identified in 65% of patients at baseline and 47.8% after systemic therapy (p = 0.53). Correlation of CD133 status in CTCs with classical clinicopathological characteristics and response to therapy was performed. Her2 not amplified and low Ki‐67 index were positively correlated with presence of CK⁺/CD133⁺ CTCs. Before any treatment, CK⁺/CD133⁺ CTCs were more frequently isolated in patients with luminal BC subtype. No statistically significant differences were found between proportion of CK⁺/CD133⁺ CTCs and BC subtypes after systemic therapy, implying a relative enrichment of CK⁺/CD133⁺ CTCs in triple negative and HER2‐amplified tumors. While CK⁺/CTCs decreases after chemotherapy when analyzing the whole population, CK⁺/CD133⁺ CTCs were enriched in post‐treatment samples in nonluminal BC subtypes. These findings suggest the potential role of CD133 as a promising marker of chemoresistance in nonluminal BC patients. Further prospective studies and extensive preclinical modeling will be needed to confirm whether CD133 is a marker of resistance to chemotherapy, and its role as a target for novel anticancer therapies targeting cancer stem cells and tumor vasculature.     

Characterization of the conversion between CD133+ and CD133- cells in colon cancer SW620 cell line

The state of cancer stem cells (CSC) under reversible fluctuations, which has been revealed in breast cancer cells most recently, suggests that subpopulations with distinct phenotypes and functions within cancer cells can undergo inter-conversion. To investigate the possibility in colon cancer cells, we employed CD133 as the CSC marker, and characterized CD133 expression pattern and the biological features of the CD133⁺ and CD133^- subsets. Flow cytometry revealed that CD133 was bimodally expressed in SW620 cells among eight colon cancer cell lines. The CD133⁺ clonal SW620 cells displayed a differential gene expression profile, higher cellular reactive oxygen species (ROS), enhanced tumorigenesis and resistance to 5-fluorouracil. The conversion in term of the CD133 phenotype of the sorted cells was observed in vitro and in vivo. The fraction of the CD133⁺ cells decreased from 99% to 80% in the sorted CD133⁺ population while rising from 5 to 10% in the sorted CD133^- population during the first 20-day cultivation and then stayed almost unchanged. A fraction (about 20%) of the CD133⁺ clonal cells lost their CD133 marker while about 10% of the CD133^- clonal cells acquired the CD133 marker. 5-Azacytidine enhanced the fraction of the CD133⁺ cells in both of the CD133⁺ and CD133^- clonal cells. Our data demonstrate that CD133 expression is dynamic and reversible, and reveal the inter-conversion between the CD133⁺ and the CD133^- SW620 cells, suggesting that the CD133 phenotype of SW620 cell population is retained by the conversion between the two cell subsets.     

CD24 negative lung cancer cells,possessing partial cancer stem cell properties,cannot be considered as cancer stem cells

Cancer stem cells (CSCs) play vital role in lung cancer progression, resistance, metastasis and relapse. Identifying lung CSCs makers for lung CSCs targeting researches are critical for lung cancer therapy. In this study, utilizing previous identified lung CSCs as model, we compared the expression of CD24, CD133 and CD44 between CSCs and non-stem cancer cells. Increased ratio of CD24- cells were found in CSCs. CD24- cells were then sorted by flow cytometry and their proliferative ability, chemo-resistance property and in vivo tumor formation abilities were detected. A549 CD24- cells formed smaller colonies, slower proliferated in comparison to A549 CD24+ cells. Besides, A549 CD24- exhibited stronger resistance to chemotherapy drug. However, A549 CD24- didn’t exert any stronger tumor formation ability in vivo, which is the gold standard of CSCs. These results showed that CD24- A549 cells showed some properties of CSCs but not actually CSCs. This study provides evidence that CD24 cannot be considered as lung CSCs marker.