Emodin reverses gemcitabine resistance in pancreatic cancer cells via the mitochondrial apoptosis pathway in vitro

Gemcitabine resistance is a common problem of pancreatic cancer chemotherapy, and how to reverse it plays an important role in the treatment of pancreatic cancer. This study investigated the effect of emodin on the gemcitabine-resistant pancreatic cancer cell line SW1990/Gem, and explored the potential mechanism of its action. SW1990/Gem was obtained by culture of the pancreatic cancer cell line SW1990 in vitro by intermittently increasing the concentration of gemcitabine in the culture medium for 10 months, observing the morphology using inverted microscopy. SW1990/Gem cells were pretreated with emodin (10 μM) for different periods followed by treatment with gemcitabine (20 μM) for 48 h; cell proliferation was tested by MTT assay. SW1990/Gem cells were treated by emodin with different concentrations for 48 h, cell apoptosis was detected by flow cytometry (FCM). The expression of gene and protein, such as MDR-1 (P-gp), NF-κB, Bcl-2, Bax, cytochrome-C (cytosol), caspase-9 and -3 were measured by RT-PCR and Western blotting. The function of P-gp in SW1990/Gem cells was checked by FCM. The results showed that the SW1990/Gem cells changed greatly in morphology and the resistance index was 48.63. Emodin promoted cell apoptosis of the gemcitabine-resistant cell line SW1990/Gem in a dose-dependent manner. Emodin enhanced the SW1990/Gem cell sensitivity to gemcitabine in a time-dependent manner. Emodin monotherapy or combination with gemcitabine both decreased the gene and protein expression levels of MDR-1 (P-gp), NF-κB and Bcl-2 and inhibited the function of P-gp, but increased the expression levels of Bax, cytochrome-C (cytosol), caspase-9 and -3, and promoted cell apoptosis. This demonstrated that emodin had a reversing effect on the gemcitabine-resistant cell line SW1990/Gem, possibly via decreasing the function of P-gp and activating the mitochondrial apoptosis pathway in vitro.     

小鼠三阴性乳腺癌干样细胞对EMT 发生及其生物学行为的影响*

目的:探讨TA2 小鼠三阴性乳腺癌中乙醛脱氢酶1+（ALDH1+）和CD133+表型的乳腺癌干样细胞在上皮间充质转化（EMT ）发生中的作用,及对其生物学行为的影响。方法:使用流式细胞术分析TA2 小鼠三阴性乳腺癌组织中ALDH1 及CD133 的表达量并分选出具有ALDH1+、ALDH1-、CD133+、CD133-表型的乳腺癌细胞,将其分别接种于TA2 小鼠,根据细胞表型不同设置为AL?DH1+、ALDH1-,CD133+、CD133-组,观察肿瘤生长情况,并制成组织切片,行三阴性乳腺癌中乳腺癌干细胞表面标记物ALDH1、CD133 与EMT 相关蛋白Twist1、E-cadherin 和VE-cadherin的免疫组织化学检测,分析其表达差异。结果:乳腺癌干细胞标记物ALDH1 及CD133 在TA2 小鼠三阴性乳腺癌中表达率分别为31.2% 和6.5% 。ALDH1+、CD133+组肿瘤生成能力明显强于ALDH1-、CD133-组。免疫组织化学结果显示ALDH1、Twist1、VE-cadherin在ALDH1+组的表达明显高于ALDH1-组（均P < 0.05）,E-cadherin在ALDH1+组的表达低于ALDH1-组（P < 0.05）。 CD133、Twist1、VE-cadherin在CD133+组的表达明显高于CD133-组（均P < 0.05）,E-cadherin 在CD133+组的表达低于CD133-组（P < 0.05）。 结论:TA2 小鼠三阴性乳腺癌中ALDH1+和CD133+表型的乳腺癌干样细胞可影响EMT 相关蛋白的表达,并促进三阴性乳腺癌的形成。      

Evaluation of CD44 and CD133 as cancer stem cell markers for colorectal cancer

Colorectal cancer (CRC) is a major cause of cancer-related mortality in the world. Recently, a number of studies have demonstrated that cancer stem cells (CSCs) present in colorectal cancer tissues, are responsible for resistance to conventional therapies. Therefore, effective recognition of CSCs is of great importance. In the present study, to explore the potential characterizations of CSCs by the expression of specific cell surface markers such as CD133 and CD44, we screened six CRC cell lines using western blotting, immunofluorescence and flow cytometry. SW620, one of the six cell lines analyzed, was sorted into four subpopulations by fluorescence activated cell sorting (FACS). The capability of colony formation, proliferation rate, apoptosis, drug resistance, as well as their migratory and invasion potential were detected. The results revealed that the combination of CD44 and CD133 correlates with the features of CSCs in SW620 cells. CD44?positive cells showed more robust colony formation, higher proliferation, less spontaneous apoptosis, a higher resistance to drug-induced cell death, and were enriched after drug treatment. Among CD44?positive SW620 cells, the CD133?negative subpopulation was more migratory and invasive, which means that CD44+CD133- correlates with most of features proposed for CSCs. Overall, the data presented herein showed that CRCs have a wide range of expression for CD44 and CD133; it is unlikely the CSCs can be characterized by any single marker or the same set of markers for all colon cancer cells. For SW620 cells, the CSCs are likely represented by the CD44+CD133- surface marker. This finding of CSC markers represented by one positive and one negative is in line with CSCs in other tumors, such as CD34+CD38- for acute myeloid leukemia; CD44+CD24- for breast and pancreatic tumors. The absence of surface molecule(s) on CSCs will make it even more difficult to track and target this group of minority cells.     

CD44 enhances the epithelial-mesenchymal transition in association with colon cancer invasion

The metastatic process involves the migration and invasion of cancer cells throughout the body to produce secondary tumors at distant sites. Through of epithelial-mesenchymal transition (EMT), cancer cells employ developmental processes to gain migratory and invasive properties. CD44 is the transmembrane adhesion receptor for Hyaluronan (HA) and plays a central role in the remodeling and degradation of HA that leads to cell migration, as well as to cancer invasion and metastasis. CD44 is highly expressed in primary and metastatic colon cancer but lowly expressed in normal tissues. We evaluated the impact of CD44 on EMT and invasion of colon cancer cells. The functional role of CD44 in EMT was determined by the overexpression or knockdown of CD44. CD44 was overexpressed by transfection with plasmid-RT-PCR product and knockdown of CD44 by small hairpin RNA (shRNA)-mediated depletion of CD44 in SW480 colon cancer cells. Morphological changes were evaluated by confocal laser microscopy in the culture media. The expression of EMT markers (E-cadherin/N-cadherin/vimentin/fibronectin/actin/MMPs) and CD44/EGFR/PI3K-Akt signaling were evaluated using western blotting. The influence of EMT in tumor biology was assessed with proliferation, migration and invasion assays. EMT changes increased in CD44-overexpressing SW480 cells and decreased in CD44 knockdown cells. CD44 activation induced expression of EGFR and activation of phosphatidylinositol 3' kinase (PI3K)/Akt and expression of glycogen synthase kinase-3 β (GSK-3β). In terms of EMT markers, CD44 downregulated E-cadherin expression, upregulated N-cadherin, α-actin, vimentin, fibronectin and MT1-MMP, and inhibited the formation of the membrane-associated E-cadherin-β-catenin complex, which resulted in cell invasion and migration.     

CD4+CD25+调节性T 细胞对乳腺癌细胞上皮间质转化和ALDH1+干样细胞的影响*

目的:研究CD4+CD25+调节性T 细胞（regulatory T cells ,Tregs）对乳腺癌细胞上皮间质转化（epithelial-mesenchymal transition ,EMT ）、细胞迁移侵袭能力,及ALDH1+干样细胞比例的影响。方法:采用免疫磁珠法分离乳腺癌患者外周血中CD4+CD25+Tregs,CD4+CD25+Tregs与乳腺癌BT474、MCF-7 细胞系共培养（共培养组）,BT474、MCF-7 单独培养（对照组）。 检测共培养组和对照组乳腺癌细胞EMT 相关标志物表达的变化,及细胞迁移和侵袭能力的变化。此外,检测BT474 细胞中ALDH1+干样细胞、微球形成能力和自我更新能力的变化。结果:CD4+CD25+Tregs诱导BT474 和MCF-7 细胞间质性标志物表达增高,诱导MCF-7 细胞上皮性标志物E-cadherin 表达降低。CD4+CD25+Tregs诱导BT474 和MCF-7 细胞迁移和侵袭能力上调。共培养组BT474 细胞中ALDH1+干样细胞比例、微球体形成能力、自我更新能力较对照组增强。结论:CD4+CD25+Tregs可诱导乳腺癌细胞发生EMT ,增强细胞体外迁移和侵袭能力,同时促进ALDH1+干样细胞增加。      

Anti-CSC Effects in Human Esophageal Squamous Cell Carcinomas and Eca109/9706 Cells Induced by Nanoliposomal Quercetin Alone or Combined with CD 133 Antiserum

CD133 was recently reported to be a cancer stem cell and prognostic marker. Quercetin is considered asa potential chemopreventive agent due to its involvement in suppression of oxidative stress, proliferation andmetastasis. In this study, the expression of CD133/CD44 in esophageal carcinomas and Eca109/9706 cells wasexplored. In immunoflurorescence the locations of CD133+ and multidrug resistance 1 (MDR 1)+ in the sameE-cancer cells were coincident, mainly in cytomembranes. In esophageal squamous cell carcinomas detected bydouble/single immunocytochemistry, small CD133+ cells were located in the basal layer of stratified squamousepithelium, determined as CSLC (cancer stem like cells); CD44+ surrounding the cells appeared in diffuse pattern,and the larger CD44+ (hi) cells were mainly located in the prickle cell layer of the epithelium, as progenitor cells.In E-cancer cells exposed to nanoliposomal quercetin (nLQ with cytomembrane permeability), down-regulationof NF-κBp65, histone deacetylase 1 (HDAC1) and cyclin D1 and up-regulation of caspase-3 were shown byimmunoblotting, and attenuated HDAC1 with nuclear translocation and promoted E-cadherin expression weredemonstrated by immunocytochemistry. In particular, enhanced E-cadherin expression reflected the reversedepithelial mesenchymal transition (EMT) capacity of nLQ, acting as cancer attenuator/preventive agent. nLQacting as an HDAC inhibitor induced apoptotic cells detected by TUNEL assay mediated via HDAC-NF-κBsignaling. Apoptotic effects of liposomal quercetin (LQ, with cytomembrane-philia) combined with CD133antiserum were also detected by CD133 immunocytochemistry combined with TUNEL assay. The combinationcould induce greater apoptotic effects than nLQ induced alone, suggesting a novel anti-CSC treatment strategy.     

吉西他滨耐药胰腺癌细胞系的耐药机制

目的探讨吉西他滨耐药胰腺癌细胞系的耐药机制。方法应用免疫组织化学方法和逆转录PCR法（RT—PCR）,对吉西他滨耐药细胞系的耐药机制进行了研究。选用沙尔威辛（SAL）进行逆转耐药实验,采用了RT—PCR法、流式细胞仪和MTT法,评估SAL逆转耐药的效果。结果免疫组织化学法显示,耐药细胞SW1990-GEM的P-糖蛋白（P—gP）表达为弱阳性,其亲本细胞SW1990为阴性。多药耐药相关蛋白（MRP）在两细胞系表达均为阴性。SW1990-GEM的多药耐药基因（mdr-1）在mRNA水平上的转录比其亲本细胞系SW1990增强;脱氧胞苷激酶（dCK）基因的转录减少;核苷酸还原酶（RR）基因的转录增强。经过SAL作用后,mdr-1在mRNA水平上的转录减少。流式细胞仪显示,经过4,30,60,90nmol／LSAL作用后,细胞内罗丹明123的蓄积累分别增加1．04,1．16,1．39,1．72倍。用4nmol／LSAL进行逆转吉西他滨耐药实验,未接受SAL处理的对照组对吉西他滨的IC50为203．72μmol／L;经SAL作用1h后再加吉西他滨组的IC50为121．36μmol／L（P=0．219）;经SAL作用24h后再加吉西他滨组的IC59为121．64μmol／L（P=0．167）。结论胰腺癌细胞对吉西他滨耐药的原因与dCK减少有关,同时也与mdr-1和RR升高相关。SAL能够下调SW1990-GEM耐药细胞的mdr-1和P—gP表达,但低浓度的SAL不能逆转SW1990-GEM对吉西他滨的耐药。     

Enhanced antitumor efficacy by the combination of emodin and gemcitabine against human pancreatic cancer cells via downregulation of the expression of XIAP in vitro and in vivo

XIAP and NF-κB play an important role in chemotherapy resistance in pancreatic cancer. The purpose of this study was to explore the role of XIAP and NF-κB in potentiating the antitumor effect of gemcitabine by emodin in pancreatic cancer. SW1990 cells were treated by sodium chloride, gemcitabine, emodin or their combination (gemcitabine plus emodin). Cellular proliferation and apoptosis were detected by Cell Counting kit-8 (CCK-8) assay and flow cytometry in?vitro. The combination therapy more significantly inhibited SW1990 cell growth and induced a higher percentage of apoptosis than monotherapy. Gemcitabine upregulated the expression of XIAP and NF-κB, while emodin or emodin plus gemcitabine downregulated them compared to the control group in?vitro. SW1990 cells were used to establish orthotopic pancreatic tumor models in nude mice. Tumor-bearing mice were treated with sodium chloride, emodin, gemcitabine or their combination. After being treated for 4 weeks, the nude mice were imaged with high-resolution positron emission tomography (microPET) and fluorine-18-labeled fluorodeoxyglucose (18F-FDG) to detect the tumor/non-tumor ratio (T/NT ratio) and standard uptake value (SUV). The mice were sacrificed to determine tumor weight. The combination of emodin and gemcitabine showed more significant reduction in the T/NT ratio, SUV and tumor weight compared to monotherapy. The mRNA levels and the protein expression of XIAP and NF-κB were upregulated in the gemcitabine group, while they were downregulated in the emodin group and the combination group in?vivo. Ki-67 prolif-eration index and TUNEL assay results also showed that emodin enhanced tumor apoptosis induced by gemcitabine in?vivo. This study suggests that emodin enhances the antitumor effect of gemcitabine in SW1990 pancreatic cancer in?vitro and in?vivo, which may be via the downregulation of NF-κB expression, thus inhibiting the expression of XIAP.     

乳腺浸润性导管癌组织中ALDH1+/CD133+干细胞样细胞与血管生成的关系

目的 探讨乳腺浸润性导管癌组织中肿瘤干细胞标志物ALDH1、CD133的表达及其与肿瘤血管生成的关系。方法 应用免疫组织化学双染法检测120例乳腺浸润性导管癌组织中ALDH1⁺/CD133⁺ 干细胞样细胞,单染法检测血管性标记CD34、CD105及VEGF的表达情况。统计ALPH1⁺/CD133⁺干细胞样细胞与临床病理因素;CD34、CD105与VEGF的关系。结果 25.83％（31/120）的病例存在ALDH1⁺/CD133⁺干细胞样细胞,ALDH1⁺/CD133⁺干细胞样细胞与ER、VEGF的表达及MVD均相关（P＜0.05）,但与年龄、肿瘤直径、PR、Her-2、组织学分级及淋巴结转移均无关（P＞0.05）。结论 乳腺浸润性导管癌组织中ALDH1⁺/CD133⁺干细胞样细胞可能通过调节VEGF的表达促进肿瘤新生血管的生成。     

Oct-4 and Nanog promote the epithelial-mesenchymal transition of breast cancer stem cells and are associated with poor prognosis in breast cancer patients

Oct-4 and Nanog in regulating the epithelial-mesenchymal transition (EMT) and metastasis of breast cancer has not been clarified. We found that both Oct-4 and Nanog expression were significantly associated with tumor pathology and poor prognosis in 126 breast cancer patients. Characterization of CD44+CD24-Cancer stem cell(CSC) derived from breast cancer cells indicated that CSC rapidly formed mammospheres and had potent tumorigenicity in vivo. Furthermore, TGF-β up-regulated the expression of Oct-4, Nanog, N-cadherin, vimentin, Slug, and Snail, but down-regulated E-cadherin and cytokeratin 18 expression, demonstrating that CSC underwent EMT. Knockdown of both Oct-4 and Nanog expression inhibited spontaneous changes in the expression of EMT-related genes, while induction of both Oct-4 and Nanog over-expression enhanced spontaneous changes in the expression of EMT-related genes in CSC. However, perturbing alternation of Oct-4 and Nanog expression also modulated TGF-β-induced EMT-related gene expression in CSC. Induction of Oct-4 and Nanog over-expression enhanced the invasiveness of CSC, but knockdown of both Oct-4 and Nanog inhibited the migration of CSC in vitro. Our data suggest that both Oct-4 and Nanog may serve as biomarkers for evaluating breast cancer prognosis. Our findings indicate that Oct-4 and Nanog positively regulate the EMT process, contributing to breast cancer metastasis.     

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.     

喉癌细胞CD44+CD133+高致瘤亚群的生物学特性

目的 筛选喉癌细胞中的高致瘤亚群,探讨其作为肿瘤干细胞的生物学特性.方法 原代培养喉癌细胞,采用流式细胞仪分选CD44+、CD133+、CD44+CD133+、CD44+CD133-细胞,并分别以1×106、1×105、1×104、1×102个/只接种于裸小鼠左腋皮下,观察各亚群成瘤时间、成瘤率、平均瘤重及肿瘤体积,筛选出在极低细胞浓度下的高致瘤亚群.采用Boyden小室体外侵袭实验,检测各亚群细胞的侵袭能力.采用免疫细胞化学染色检测各亚群细胞中干细胞抗原-1(SCA-1)及整合素β1的表达.采用逆转录聚合酶链反应(RT-PCR)和Westem blot法,检测各亚群细胞中Bmi-1基因的表达.结果 CD44+CD133+细胞以1×103个/只接种于裸小鼠,可以成瘤.当各亚群细胞以1×106个/只接种于裸小鼠4周后,CD44+CD133+细胞接种组棵小鼠的肿瘤体积和重量分别为(7726.81±196.93)mm3和(5.51±0.12)g,均大于CD44+、CD44+CD133-及未分选细胞接种组(均P<0.05),而与CD133+细胞接种组裸小鼠的肿瘤体积和重量差异无统计学意义(P>0.05).CD44+CD133+细胞24 h的侵袭细胞数为83.62±1.61,显著高于其他各亚群喉癌细胞.CD44+CD133+细胞高表达整合素β1和SCA-1.Bmi-1 mRNA在CD44+CD133+细胞中的表达水平为0.951±0.112,显著高于CD44+CD133-细胞和未分选的喉癌细胞(0.532±0.214和0.268±0.193,均P<0.01);Bmi-1蛋白在CD133+和CD44+CD133+细胞中高表达,而在CD44+、CD44+CDi33-和未分选的喉癌细胞中仅有少量表达.结论 CD44+CD133+喉癌细胞具有高致瘤性及肿瘤干细胞的生物学特性,可能是喉癌恶性增殖的根源,并有望成为喉癌治疗的新靶点.     

LIN28B suppresses microRNA let-7b expression to promote CD44+/LIN28B+ human pancreatic cancer stem cell proliferation and invasion

Although the highly proliferative, migratory, and multi-drug resistant phenotype of human pancreatic cancer stem cells (PCSCs) is well characterized, knowledge of their biological mechanisms is limited. We used CD44 and LIN28B as markers to screen, isolate, and enrich CSCs from human primary pancreatic cancer. Using flow cytometry, we identified a human primary pancreatic cancer cell (PCC) subpopulation expressing high levels of both CD44 and LIN28B. CD44+/LIN28B+ PCSCs expressed high levels of stemness marker genes and possessed higher migratory and invasive ability than CD44-/LIN28B- PCCs. CD44+/LIN28B+ PCSCs were more resistant to growth inhibition induced by the chemotherapeutic drugs cisplatin and gemcitabine hydrochloride, and readily established tumors in vivo in a relatively short time. Moreover, microarray analysis revealed significant differences between the cDNA expression patterns of CD44+/LIN28B+ PCSCs and CD44-/LIN28B- PCCs. Following siRNA interference of endogenous LIN28B gene expression in CD44+/LIN28B+ PCSCs, not only was their proliferation decreased, there was also cell cycle arrest due to suppression of cyclin D1 expression following the stimulation of miRNA let-7b expression. In conclusion, CD44+/LIN28B+ cells, which possess CSC characteristics, can be reliably sorted from human primary PCCs and represent a valuable model for studying cancer cell physiology and multi-drug resistance.