Down-regulation of mitochondrial F1F0-ATP synthase in human colon cancer cells with induced 5-fluorouracil resistance

5-Fluorouracil (5-FU) is widely used for treatment of advanced colorectal cancer. However, it is common for such patients to develop resistance to 5-FU, and this drug resistance becomes a critical problem for chemotherapy. The mechanisms underlying this resistance are largely unknown. To screen for proteins possibly responsible for 5-FU resistance, cells resistant to 5-FU were derived from human colon cancer cell lines and two-dimensional gel electrophoresis-based comparative proteomics was done. Two-dimensional gel electrophoresis data showed there was lower expression of the alpha subunit of mitochondrial F(1)F(0)-ATP synthase (ATP synthase) in 5-FU-resistant cells compared with parent cells. Western blotting showed that expression of other ATP synthase complex subunits was also lower in 5-FU-resistant cell lines and that these resistant cells also showed decreased ATP synthase activity and reduced intracellular ATP content. The ATP synthase inhibitor, oligomycin A, strongly antagonized 5-FU-induced suppression of cell proliferation. When 5-FU sensitivity was compared with ATP synthase activity in six different human colon cancer cell lines, a positive correlation has been found. Furthermore, suppressed ATP synthase d-subunit expression by siRNA transfection increased cell viability in the presence of 5-FU. Bioenergetic dysfunction of mitochondria has been reported as a hallmark of many types of cancers (i.e., down-regulation of ATP synthase beta-subunit expression in liver, kidney, colon, squamous oesophageal, and lung carcinomas, as well as in breast and gastric adenocarcinomas). Our findings show that ATP synthase down-regulation may not only be a bioenergetic signature of colorectal carcinomas but may also lead to cellular events responsible for 5-FU resistance.     

Suppression of heat shock protein 27 expression promotes 5-fluorouracil sensitivity in colon cancer cells in a xenograft model

The present study investigates whether the expression levels of heat shock protein?27 (HSP27) in colon cancer cells are associated with 5-fluorouracil (5-FU) sensitivity in a xenograft model, as well as the mechanism responsible for regulating 5-FU sensitivity. HCT116 cells which have a high expression of HSP27 were stably transfected with specific short hairpin RNA (shRNA) in order to suppress HSP27 expression. The association between HSP27 protein expression levels and 5-FU sensitivity was evaluated in a mouse xenograft model. The mRNA expression of 5-FU metabolic enzymes and cell apoptosis were also analyzed in the transfected cells. The suppression of HSP27 protein expression led to enhanced 5-FU sensitivity. The mRNA expression levels of dihydropyrimidine dehydrogenase and orotate phosphoribosyltransferase, but not those of thymidylate synthase, and the number of apoptotic cells increased in the transfected cells after 5-FU exposure. In conclusion, the suppression of HSP27 expression in colon cancer cells may promote 5-FU sensitivity by inducing apoptosis, despite the acceleration in 5-FU metabolism.     

Pyrotinib Sensitizes 5-Fluorouracil-Resistant HER2⁺ Breast Cancer Cells to 5-Fluorouracil

5-Fluorouracil (5-FU) is a widely used chemotherapeutic agent for breast cancer. However, acquired chemoresistance leads to a loss of its efficacy; methods to reverse are urgently needed. Some studies have shown that pyrotinib, an ErbB receptor tyrosine kinase inhibitor, is effective against HER2+ breast cancer. However, whether pyrotinib sensitizes 5-FU-resistant breast cancer cells to 5-FU is unknown. We hypothesized that the combination of pyrotinib and 5-FU would show synergistic antitumor activity, and pyrotinib could reverse 5-FU resistance in HER2+ breast cancer cells in vitro and in vivo. Our data showed that pyrotinib inhibited the growth of 5-FU-resistant SKBR-3/FU and MDA-MB-453/FU cell lines and the parental cell lines. 5-FU remarkably suppressed the growth of SKBR-3 and MAD-MB-453 cells. However, SKBR-3/FU and MADMB-453/FU cells showed resistance to 5-FU. A combination of pyrotinib and 5-FU resulted in the synergistic inhibition of the growth of the 5-FU-resistant SKBR-3/FU and MDA-MB-453/FU cell lines and the parental cell lines. Pyrotinib decreased significantly the IC50 values of 5-FU and the thymidylate synthase (TS) mRNA expression levels in the 5-FU-resistant SKBR-3/FU and MDA-MB-453/FU cell lines and the parental cell lines and increased significantly the intracellular concentration of 5-FU in SKBR-3/FU and MDA-MB-453/FU cells. In addition, pyrotinib reduced the ABCG2 mRNA and protein expression levels in SKBR-3/FU and MDA-MB- 453/FU cells and downregulated the protein expression levels of pAKT, pHER2, and pHER4 in all four cell lines. After TS or ABCG2 in 5-FU-resistant breast cancer cells was knocked down, the sensitivity of SKBR-3/ FU and MDA-MB-453/FU cells to 5-FU was restored. Moreover, in vivo experiments demonstrated that pyrotinib in combination with 5-FU more effectively inhibited SKBR-3/FU tumor growth than either pyrotinib or 5-FU alone. In conclusion, our findings suggest that pyrotinib could restore sensitivity of 5-FU-resistant HER2+ breast cancer cells to 5-FU through downregulating the expression levels of TS and ABCG2.     

Cellular response to 5-fluorouracil (5-FU) in 5-FU-resistant colon cancer cell lines during treatment and recovery

Background  

Treatment of cells with the anti-cancer drug 5-fluorouracil (5-FU) causes DNA damage, which in turn affects cell proliferation and survival. Two stable wild-type TP53 5-FU-resistant cell lines, ContinB and ContinD, generated from the HCT116 colon cancer cell line, demonstrate moderate and strong resistance to 5-FU, respectively, markedly-reduced levels of 5-FU-induced apoptosis, and alterations in expression levels of a number of key cell cycle- and apoptosis-regulatory genes as a result of resistance development. The aim of the present study was to determine potential differential responses to 8 and 24-hour 5-FU treatment in these resistant cell lines. We assessed levels of 5-FU uptake into DNA, cell cycle effects and apoptosis induction throughout treatment and recovery periods for each cell line, and alterations in expression levels of DNA damage response-, cell cycle- and apoptosis-regulatory genes in response to short-term drug exposure.     

Inhibition of autophagy augments 5-fluorouracil chemotherapy in human colon cancer in vitro and in vivo model

Although 5-fluorouracil (5-FU)-based adjuvant chemotherapy is widely used in the treatment of colorectal cancer, novel therapeutic strategies need to be explored. It has been reported that autophagy is extensively implicated in cancer. However, the function of autophagy is not fully understood. In the present study, apoptosis induced by 5-FU in 3 human colon cancer cell lines (HCT116, DLD-1, and DLD-1/5-FU (a specific 5-FU-resistant sub-line)) was measured using MTT assay, DNA fragmentation assay, Hoechst 33342 staining, and caspase-3 immunoblotting. The autophagy activation induced by 5-FU treatment was revealed by microtubule-associated protein 1 light chain 3 (LC3) immunofluorescence and immunoblotting and p62 immunoblotting. Inhibition of autophagy by 3-methyladenine (3-MA) or small interference RNA targeting Atg7 (Atg7 siRNA) significantly augmented 5-FU-induced apoptosis. This synergistic effect of 5-FU and 3-MA was further confirmed in the DLD-1 xenograft tumour model. Tumour growth was suppressed more significantly with combination treatment than 5-FU treatment alone. In conclusion, autophagy was activated as a protective mechanism against 5-FU–induced apoptosis and its inhibition could be a promising strategy for adjuvant chemotherapy in colon cancer.     

Resistance of colon cancer cells to long-term 5-fluorouracil exposure is correlated to the relative level of Bcl-2 and Bcl-X(L) in addition to Bax and p53 status

Defects in apoptosis have been implicated in chemoresistance of colon cancer cells. We report here the ability to resist to 5-fluorouracil-induced apoptosis of 8 colon cancer cell lines differing in p53 and bax status: p53(-/0)bax(+/+) for TC7, SW480, HT-29; p53(+/+)bax(-/-) for LS174T, LoVo; p53(+/+) bax(+/-) for HCT116; p53(+/+) or p53(+/0)bax(+/+) for LS513 or HCT-EB, respectively. To approximate to the in vivo therapy, the cell lines were exposed to a long-term treatment of 5-FU. The analysis of proteins implicated in the apoptotic pathway has shown that the independent analysis of p53 or bax status was not sufficient to predict the extent of drug-resistance of all cell lines. In p53(+/+) cell lines but not in p53(-/0) cell lines, a low level of the pro-apoptotic Bax protein was correlated with a greater resistance of cells to 5-FU. In addition, we found that high levels of anti-apoptotic Bcl-2 and Bcl-x(L) proteins combined with a low level of Bax were correlated to high 5-FU resistance of wild-type p53 cell lines. The same correlation was obtained for 2 out of 3 mutated p53 cell lines. In conclusion, the relative levels of Bcl-2, Bcl-x(L) and Bax may altogether contribute to determine the resistance of a majority of colon tumor cells to long-term 5-FU treatment, whatever their p53 status.     

Molecular characterizations of derivatives of HCT116 colorectal cancer cells that are resistant to the chemotherapeutic agent 5-fluorouracil

5-Fluorouracil (5-FU) is the chemotherapeutic drug of choice for the treatment of metastatic colorectal cancer, but resistance to 5-FU remains a major obstacle to successful therapy. We generated 5-FU-resistant derivatives of the HCT116 human colon cancer cell line by serial passage of these cells in the presence of increasing 5-FU concentrations in an attempt to elucidate the biological mechanisms involved in resistance to 5-FU. Two resultant resistant derivatives, HCT116 ResB and ResD, were characterized for resistance phenotypes, genotypes, and gene expression using cells maintained long-term in 5-FU-free media. Compared to parental HCT116 cells that respond to 5-FU challenge by inducing high levels of apoptosis, ResB and ResD derivatives had significantly reduced apoptotic fractions when transiently challenged with 5-FU. ResB and ResD cells were respectively 27- and 121-fold more resistant to 5-FU, had increased doubling times, and significantly increased plating efficiencies compared to the parental cells. Both resistant derivatives retained the wild-type TP53 genotype, TP53 copy number and CGH profile characteristic of the parental line. Alterations in gene expression in the resistant derivatives compared to the parental line were assessed using oligonucleotide microarrays. Overall, the 5-FU-resistant derivatives were characterized by reduced apoptosis and a more aggressive growth phenotype, consistent with the observed up-regulation of apoptosis-inhibitory genes (e.g., IRAK1, MALT1, BIRC5), positive growth-regulatory genes (e.g., CCND3, CCNE2, CCNF, CYR61), and metastasis genes (e.g., LMNB1, F3, TMSNB), and down-regulation of apoptosis-promoting genes (e.g., BNIP3, BNIP3L, FOXO3A) and negative growth-regulatory genes (e.g., AREG, CCNG2, CDKN1A, CDKN1C, GADD45A). 5-FU metabolism-associated genes (e.g., TYMS, DTYMK, UP) and DNA repair genes (e.g., FEN1, FANCG, RAD23B) were also up-regulated in one or both resistant derivatives, suggesting that the resistant derivatives might be able to overcome both 5-FU inhibition of thymidylate synthase and the DNA damage caused by 5-FU, respectively. Development of 5-FU resistance thus appears to encompass deregulation of apoptosis-, proliferation-, DNA repair-, and metastasis-associated regulatory pathways.     

UGCG通过调控MDR1/P-gp参与人结肠癌奥沙利铂耐药的初步研究

目的 建立人结肠癌耐奥沙利铂（L-OHP）细胞株,检测该细胞株的多药耐药性并初步探讨其可能的耐药机制。方法 以人结肠癌细胞HCT116为对象,采用药物浓度梯度递增诱导法建立人结肠癌耐奥沙利铂细胞株HCT-116/L-OHP。CCK-8法检测L-OHP、顺铂（DDP）、5-氟尿嘧啶（5-Fu）对亲本细胞和耐药细胞株的半数抑制浓度（IC50）。使用UDP-葡萄糖神经酰胺糖基转移酶（UGCG）siRNA转染HCT-116/L-OHP细胞,实时荧光定量 PCR和Western blot检测干扰前后UGCG基因和多药耐药基因1（MDR1）mRNA及其编码的蛋白表达水平。结果 HCT-116/L-OHP对L-OHP的耐药指数为10.5,与DDP有一定程度的交叉耐药,耐药指数为4.61,但对5-Fu无交叉耐药。耐药细胞HCT-116/L-OHP中UGCG、MDR1 mRNA和UGCG、P-糖蛋白（P-gp, MDR1编码的蛋白）表达均增加,相比HCT-116细胞,差异具有统计学意义（P<0.05）。UGCG siRNA成功抑制HCT-116/L-OHP细胞中UGCG的表达,各干扰组MDR1 mRNA、P-gp表达减少,与对照组相比差异具有统计学意义（P<0.05）。结论 成功构建了人结肠癌耐药细胞株;UGCG基因通过调控MDR1/P-gp的表达参与人结肠癌奥沙利铂的耐药机制的形成。     

Violacein synergistically increases 5-fluorouracil cytotoxicity, induces apoptosis and inhibits Akt-mediated signal transduction in human colorectal cancer cells

Despite recent additions to the armory of chemotherapeutic agents for colorectal cancer (CRC) treatment, the results of chemotherapy remain unsatisfactory. 5-Fluorouracil (5-FU) still represents the cornerstone of treatment and resistance to its actions is a major obstacle to successful chemotherapy. Therefore, new active agents in CRC and agents that increase the chemosensitivity of cancer cells to 5-FU are still urgently required. Violacein, a pigment isolated from Chromobacterium violaceum in the Amazon river, has a diverse spectrum of biological activities, and represents a novel cytotoxic drug with known antileukemic properties. To assess the suitability of violacein as a chemotherapeutic agent in CRC its cytotoxic effects were evaluated both as a single agent and in combination with 5-FU. Its underlying mechanisms of action were further investigated by studying its effects on the cell cycle, apoptosis and cell survival pathways [phosphatidylinositol-3-kinase/Akt, p44/42 mitogen activated protein kinase and nuclear factor kappaB (NF-kappaB)] in colon cancer cell lines. Violacein inhibits the growth of all four colon cancer cell lines tested. It induces apoptosis, and potentiates the cytotoxic effect of 5-FU in a poorly differentiated microsatellite unstable cell line (HCT116). Violacein causes cell cycle block at G(1), upregulates p53, p27 and p21 levels and decreases the expression of cyclin D1. Violacein leads to dephosphorylation of retinoblastoma protein and activation of caspases and a pancaspase inhibitor abrogates its biological activity. Our data provide evidence that violacein acts through the inhibition of Akt phosphorylation with subsequent activation of the apoptotic pathway and downregulation of NF-kappaB signaling. This leads to the increase in chemosensitivity to 5-FU in HCT116 colon cancer cells. Taken together, our findings suggest that violacein will be active in the treatment of colorectal tumors and offers new prospects for overcoming 5-FU resistance.     

5-Fluorouracil induces apoptosis in human colon cancer cell lines with modulation of Bcl-2 family proteins.

Recently, apoptosis has been implicated as one of the end points of cells exposed to chemotherapeutic agents. The p53 and Bcl-2 family of proteins are involved in chemotherapy-induced apoptosis, but in a cell type-dependent manner. We sought to determine the roles played by the p53 and Bcl-2 family of proteins in 5-fluorouracil (5-FU)-induced apoptosis of human colon cancer cell lines. We first studied the p53 genetic and functional status, and then 5-FU, at inhibitory concentration of 50% (IC50) doses, was used to induce apoptosis, which was confirmed by morphological analysis and enzyme-linked immunosorbent assay (ELISA). Bcl-2, Bcl-X(L), Bax, Bad, Bak and p53 protein expression was analysed by Western blotting. Using five human colon cancer cell lines, we found that equitoxic (IC50) doses of 5-FU induced apoptosis in both wild-type p53 and mutant p53 cells. Analysis of the steady-state levels of Bcl-2 family proteins showed high expression of Bcl-X(L) in all of the cell lines except Colo320. Bcl-2 was expressed in two of them. Bax presented with the lowest basal expression and Bad showed homogeneous expression. On the other hand, Bak expression varied more than fivefold among these cells. In cells containing wild-type p53 (e.g. LoVo), 5-FU-induced apoptosis was accompanied by increased expression of Bax and Bak without consistent modulation of other bcl-2 family proteins. In contrast in cells containing mutant p53 (e.g. DLD1), Bak expression was remarkably increased. There was a significant correlation between chemosensitivity and Bcl-X(L) to Bax ratio, rather than Bcl-2 to Bax. In conclusion, these results suggest that some members of the Bcl-2 family of proteins, in human colon cancer cell lines, are modulated by 5-FU and that the ratio of Bcl-X(L) to Bax may be related to chemosensitivity to 5-FU.     

Down-regulation of cIAP2 enhances 5-FU sensitivity through the apoptotic pathway in human colon cancer cells

Currently 5-fluorouracil (5-FU) plays a central role in the chemotherapeutic regimens for colorectal cancers and thus it is important to understand the mechanisms that determine 5-FU sensitivity. The expression profiles of human colon cancer cell line DLD-1, its 5-FU-resistant subclone DLD-1/FU and a futher 21 types of colon cancer cell lines were compared to identify the novel genes defining the sensitivity to 5-FU and to estimate which population of genes is responsible for 5-FU sensitivity. In the hierarchical clustering, DLD-1 and DLD-1/FU were most closely clustered despite over 100 times difference in their 50% inhibitory concentration of 5-FU. In DLD-1/FU, the population of genes differentially expressed compared to DLD-1 was limited to 3.3%, although it ranged from 4.8% to 24.0% in the other 21 cell lines, thus indicating that the difference of 5-FU sensitivity was defined by a limited number of genes. Next, the role of the cellular inhibitor of apoptosis 2 ( cIAP2) gene, which was up-regulated in DLD-1/FU, was investigated for 5-FU resistance using RNA interference. The down-regulation of cIAP2 efficiently enhanced 5-FU sensitivity, the activation of caspase 3/7 and apoptosis under exposure to 5-FU. The immunohistochemistry of cIAP2 in cancer and corresponding normal tissues from colorectal cancer patients in stage III revealed that cIAP2 was more frequently expressed in cancer tissues than in normal tissues, and cIAP2-positive patients had a trend toward early recurrence after fluorouracil-based chemotherapy. Although the association between drug sensitivity and the IAP family in colorectal cancer has not yet been discussed, cIAP2 may therefore play an important role as a target therapy in colorectal cancer. ( Cancer Sci 2009; 100: 903–913)     

Lovastatin augments apoptosis induced by chemotherapeutic agents in colon cancer cells.

Beta-hydroxy-beta-methylglutaryl coA reductase inhibitors (HRIs) inhibit isoprenylation of several members of the Ras superfamily of proteins and therefore have important cellular effects, including the reduction of proliferation and increasing apoptosis. Significant toxicity at high doses has precluded the use of HRIs as a monotherapy for cancers. We therefore studied whether combinations of the HRI lovastatin with standard chemotherapeutic agents would augment apoptosis in colon cancer cells. In the colon cancer cell lines SW480, HCT116, LoVo, and HT29, lovastatin induced apoptosis with differing sensitivity. Pretreatment with lovastatin significantly increased apoptosis induced by 5-fluorouracil (5-FU) or cisplatin in all four cell lines. Lovastatin treatment resulted in decreased expression of the antiapoptotic protein bcl-2 and increased the expression of the proapoptotic protein bax. The addition of geranylgeranylpyrophospate (10 microM) prevented lovastatin-induced augmentation of 5-FU and cisplatin-induced apoptosis; mevalonate (100 microM) was partially effective, whereas cotreatment with farnesyl pyrophosphate (100 microM) had no effect. These data imply that lovastatin acts by inhibiting geranylgeranylation and not farnesylation of target protein(s). Our data suggest that lovastatin may potentially be combined with 5-FU or cisplatin as chemotherapy for colon cancers.     

PERK信号通路介导结肠癌细胞对5-氟尿嘧啶耐药机制的研究

目的:观察PERK蛋白对结肠癌细胞药物敏感性的影响,并进一步探讨其相关作用机制。方法:结肠癌细胞系HCT116分为三组:空白对照（Control）组、下调PERK表达（si-PERK）组、阴性对照（si-NC）组;采用免疫荧光及RT-PCR验证转染效率;利用CCK-8实验检测下调PERK表达后结肠癌细胞对化疗药物5-FU的敏感性变化;Annexin V-FITC凋亡实验检测下调PERK表达对结肠癌细胞凋亡的影响;利用RT-PCR及Western Blot实验检测PERK信号通路中关键分子eIF2α、ATF4、CHOP、XIAP的mRNA及蛋白表达变化。结果:RT-PCR实验表明:与正常对照组相比,si-PERK 组mRNA的表达显著下降（P＜0.05）,免疫荧光提示转染效率达80%以上;CCK-8实验发现与si-NC组相比,5-FU对 si-PERK组细胞的半数抑制浓度（IC50）明显降低（P＜0.01）;Annexin V-FITC凋亡实验发现与si-NC组相比,si-PERK组细胞的凋亡发生率显著升高（P＜0.05）;RT-PCR及Western Blot实验发现与si-NC组相比,si-PERK组细胞中PERK信号通路下游关键分子eIF2α、ATF4、CHOP的mRNA及蛋白表达均明显降低（P＜0.05）。结论:在结肠癌细胞中,抑制PERK表达后,其可能通过下调eIF2α、ATF4、CHOP的表达促进细胞发生凋亡,从而促进细胞对化疗药物5-FU的敏感性。     

阻断己糖激酶-Ⅱ基因表达对结肠癌化疗的影响及其机制

目的：观察阻断己糖激酶-Ⅱ（ＨＫ-Ⅱ）基因表达对结肠癌ＬｏＶｏ细胞化疗敏感性的影响及其机制。方法：应用质粒介导的短发夹ＲＮＡ（ｓｈＲＮＡ）真核表达法特异性阻断ＨＫ-Ⅱ基因表达。通过半定量逆转录 聚合酶链反应（ＲＴ-ＰＣＲ）和Ｗｅｓｔｅｒｎ印迹法分析ＲＮＡ干扰效应。ＭＴＴ法检测氟尿嘧啶（５-ＦＵ）和奥沙利铂（Ｌ-ＯＨＰ）对ＬｏＶｏ细胞的半数抑制浓度（ＩＣ５０）;底物比色法测定半胱氨酸蛋白水解酶（ｃａｓｐａｓｅ）-３活性;Ｗｅｓｔｅｒｎ印迹法检测胸苷酸合成酶（ＴＳ）表达变化。结果：ＲＮＡ干扰技术特异性下调结肠癌ＬｏＶｏ细胞ＨＫ-Ⅱ基因表达,ｍＲＮＡ和蛋白质水平的表达抑制率分别为７２.１％和７１.２％。阻断ＨＫ-Ⅱ基因表达后,结肠癌ＬｏＶｏ细胞５-ＦＵ和Ｌ-ＯＨＰ的ＩＣ５０值分别为（４.７０±０.４０）μｇ／ｍｌ和（６.２７±０.５９）μｇ／ｍｌ,均明显低于正常培养细胞的（１１.９３±０.１５）μｇ／ｍｌ和（９.７７±０.６０）μｇ／ｍｌ（Ｐ＜０.０１）;与正常培养细胞相比,ＲＮＡ干扰的ＬｏＶｏ细胞ｃａｓｐａｓｅ-３活性明显增高,ＴＳ蛋白表达下降。结论：阻断ＨＫ-Ⅱ基因表达可能通过活化ｃａｓｐａｓｅ-３和降低ＴＳ表达的途径来增加结肠癌ＬｏＶｏ细胞化疗敏感性。     

结肠癌 COLO 耐药株的构建及其与肿瘤干细胞的关系

目的：构建结肠癌 COLO 耐药株,探索其功能特性及其与肿瘤干细胞的关系。方法通过逐渐递增化疗药5-氟尿嘧啶（5-FU）浓度的方法,构建了耐0．10μmol／ml 和0．20μmol／ml 5-FU 的结肠癌 COLO 耐药株各1株,分别命名为 COLO／5-FU-1、COLO／5-FU-2。从增殖能力、克隆形成能力、迁移和侵袭能力、微球体形成能力、干性基因的表达、交叉耐药等方面与亲本结肠癌细胞株 COLO 进行对比。结果在存活检测中,常规培养后第4天,结肠癌耐药株 COLO／5-FU-2、COLO／5-FU-1、亲本 COLO 细胞的 A 值分别为0．61±0．13、0．54±0．07、0．41±0．09,差异有统计学意义（F ＝63．43,P ＝0．033）。随着耐5-FU 药物浓度的增加,COLO 耐药株的克隆形成率逐渐增强,COLO／5-FU-2、COLO／5-FU-1、亲本 COLO的克隆形成率依次为（87．6±12．7）％、（65．3±9．7）％、（38．5±7．6）％,差异有统计学意义（F ＝33．64, P ＝0．017）。COLO／5-FU-2、COLO／5-FU-1、亲本 COLO 每高倍视野中迁移穿过基底膜的细胞数分别为（482±39）个、（434±45）个、（373±38）个,侵袭穿过基底膜的细胞数分别为（174±42）个、（112±31）个、（87±29）个,差异均有统计学意义（F ＝109．61,P ＝0．009;F ＝67．31,P ＝0．032）。与亲本结肠癌细胞株COLO 比较,耐药株表达更高的干性基因,差异有统计学意义（F ＝47．31,P ＝0．042）;且耐药株对其他化疗药如米托蒽醌存在交叉耐药[如给药96 h,米拖蒽醌对亲本 COLO 的抑制率高于 COLO／5-FU-1、COLO／5-FU-2（0．749±0．042、0．423±0．024、0．342±0．018）,差异有统计学意义（F ＝12．61,P ＝0．028）]。COLO／5-FU-2、COLO／5-FU-1、亲本 COLO 细胞的微球体形成率依次为（8．90±0．97）％、（6．20±0．75）％、（3．90±0．32）％,差异有统计学意义（F ＝164．32,P ＝0．006）。结论结肠癌 COLO耐药株有肿瘤干细胞样细胞的特点,是富集了的肿瘤干细胞。