Aldehyde dehydrogenase in combination with CD133 defines angiogenic ovarian cancer stem cells that portend poor patient survival

Markers that reliably identify cancer stem cells (CSC) in ovarian cancer could assist prognosis and improve strategies for therapy. CD133 is a reported marker of ovarian CSC. Aldehyde dehydrogenase (ALDH) activity is a reported CSC marker in several solid tumors, but it has not been studied in ovarian CSC. Here we report that dual positivity of CD133 and ALDH defines a compelling marker set in ovarian CSC. All human ovarian tumors and cell lines displayed ALDH activity. ALDH(+) cells isolated from ovarian cancer cell lines were chemoresistant and preferentially grew tumors, compared with ALDH(-) cells, validating ALDH as a marker of ovarian CSC in cell lines. Notably, as few as 1,000 ALDH(+) cells isolated directly from CD133(-) human ovarian tumors were sufficient to generate tumors in immunocompromised mice, whereas 50,000 ALDH(-) cells were unable to initiate tumors. Using ALDH in combination with CD133 to analyze ovarian cancer cell lines, we observed even greater growth in the ALDH(+)CD133(+) cells compared with ALDH(+)CD133(-) cells, suggesting a further enrichment of ovarian CSC in ALDH(+)CD133(+) cells. Strikingly, as few as 11 ALDH(+)CD133(+) cells isolated directly from human tumors were sufficient to initiate tumors in mice. Like other CSC, ovarian CSC exhibited increased angiogenic capacity compared with bulk tumor cells. Finally, the presence of ALDH(+)CD133(+) cells in debulked primary tumor specimens correlated with reduced disease-free and overall survival in ovarian cancer patients. Taken together, our findings define ALDH and CD133 as a functionally significant set of markers to identify ovarian CSCs.     

ALDH+ tumor-initiating cells exhibiting gain in NOTCH1 gene copy number have enhanced regrowth sensitivity to a γ-secretase inhibitor and irinotecan in colorectal cancer

The Notch signaling pathway has been shown to be upregulated in colorectal cancer (CRC) and important for the self-renewal of cancer stem cells. In this study, we evaluated the efficacy of PF-03084014, a γ-secretase inhibitor, in combination with irinotecan to identify the effects of treatment on tumor recurrence and the tumor-initiating population in our CRC preclinical explant model. The combination of PF-03084014 and irinotecan had the greatest effect at reducing tumor growth on four CRC tumors when compared with treatment with PF-03084014 or irinotecan alone. The combination significantly reduced tumor recurrence in two CRC explants (CRC001 and CRC036) after treatment was discontinued. Both of these tumors exhibited elevated baseline levels of Notch pathway activation as well as an increase in NOTCH1 gene copy number when compared with the two CRC explants (CRC026 and CRC027) where tumors reappeared quickly after termination of treatment. Isolation and injection of aldehyde dehydrogenase (ALDH(+) and ALDH(-)) cells in an in vivo explant model demonstrated that the ALDH(+) cell population were tumorigenic. Evaluation of the ALDH(+) cells after 28 days of treatment showed that the combination reduced the ALDH(+) population in the tumors that did not regrow. Furthermore, ALDH(+) cells from CRC001 and CRC027 were injected in vivo and treated immediately for 28 days. Two months after treatment, tumors were evident in the combination treatment group for CRC027 but not for CRC036. These results indicate the combination of PF-03084014 and irinotecan may be effective in reducing tumor recurrence in CRC patients whose tumors exhibit elevated levels of the Notch pathway.     

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。      

Notch signaling in CD66+ cells drives the progression of human cervical cancers

Human epithelial tumor progression and metastasis involve cellular invasion, dissemination in the vasculature, and regrowth at metastatic sites. Notch signaling has been implicated in metastatic progression but its roles have yet to be fully understood. Here we report the important role of Notch signaling in maintaining cells expressing the carcinoembryonic antigen cell adhesion molecule CEACAM (CD66), a known mediator of metastasis. CD66 and Notch1 were studied in clinical specimens and explants of human cervical cancer, including specimens grown in a pathophysiologically relevant murine model. Gene expression profiling of CD66(+) cells from primary tumors showed enhanced features of Notch signaling, metastasis, and stemness. Significant differences were also seen in invasion, colony formation, and tumor forming efficiency between CD66(+) and CD66(-) cancer cells. Notably, CD66(+) cells showed a marked sensitivity to a Notch small molecule inhibitor. In support of studies in established cell lines, we documented the emergence of a tumorigenic CD66(+) cell subset within a metastatic lesion-derived cervical-cancer cell line. Similar to primary cancers, CD66 expression in the cell line was blocked by chemical and genetic inhibitors of ligand-dependent nuclear Notch signaling. Collectively, our work on the oncogenic properties of CD66(+) cells in epithelial cancers provides insights into the nature of tumor progression and offers a mechanistic rationale to inhibit the Notch signaling pathway as a generalized therapeutic strategy to treat metastatic cancers.     

CD133 expression: a potential prognostic marker for non-small cell lung cancers

Background

CD133 is a membrane glycoprotein containing five transmembrane loops. Previous reports suggest that a CD133-positive subpopulation of multipotent cells with extensive proliferative and self-renewal characteristics has biological features of a cancer stem cell. In addition, the presence of CD133-positive cells was associated with a significantly poorer prognosis for some solid tumors, compared to those with CD133-negative cells. However, the clinicopathological significance of CD133 in non-small cell lung cancer (NSCLC) remains controversial.

Methods

We conducted immunohistochemical assessment of 161 NSCLCs surgically resected at Hokkaido University Hospital between 1982 and 1994 to evaluate correlations between CD133 expression and various clinicopathological features.

Results

CD133 expression was significantly correlated with pathological stages (pStages) II, III, and IV for the various NSCLC types analyzed and was an independent factor for unfavorable prognosis in this population (hazard ratio = 3.157, P = 0.015).

Conclusion

CD133 expression was correlated with pStage and was predictive of unfavorable prognosis in patients with pStages II, III, and IV NSCLC. These results suggest the possibility of using CD133 as a novel prognostic marker in these patients.     

Associated microsatellite alterations in mitochondrial DNA and in TP53 in thoracic esophageal squamous cell carcinoma

Chemoresistance and self-renewal of cancer stem cells (CSC), found in many tumors including pancreatic ductal adenocarcinoma (PDAC), are believed to underlie tumor mass regrowth. The distribution of cells carrying the putative stem-cell markers CD133, Nestin, Notch1-4, Jagged1 and 2, ABCG2 and aldehyde dehydrogenase (ALDH1) was assessed immunohistochemically using PDAC and normal pancreas tissue microarrays. The immunoreactivity was semi-quantitatively graded against the normal pancreas and was correlated with the differentiation grade and disease stage. No statistical significant differences were found between normal pancreas and PDAC in the expression of Nestin, Notch1, 3 and 4, ABCG2 or ALDH1. Notch2 and Jagged1 and 2 expression were increased in PDAC. CD133-positive cells were above-normal in PDAC, but the difference was not statistically significant. Nestin, Notch1-4, Jagged1, ABCG2 and ALDH1 immunostaining scores were not correlated with tumor grade or disease stage. CD133 and Notch2 expression was significantly inversely correlated with tumor grade, but not disease stage. Notch3 immunostaining positively correlated with tumor stage, but not with differentiation grade. Jagged2 protein expression correlated inversely with disease stage, but not with tumor grade. From the clinical standpoint, improved delineation of the tumor CSC signature, putatively responsible for tumor initiation and recurrence after initial response to chemotherapy, may offer novel therapeutic targets for this highly lethal cancer.     

姜黄素调控Notch信号通路对肺癌干细胞增殖及凋亡的影响

目的:研究姜黄素对肺癌干细胞增殖及凋亡的影响。方法:利用免疫磁珠标记肺癌表面标记物乙醛脱氢酶1(ALDH1)，从肺癌A549细胞系中分离肺癌干细胞；MTT实验检测姜黄素对肺癌干细胞增殖的影响；流式细胞仪检测姜黄素对肺癌干细胞凋亡的影响；Western blot检测Notch1和Hes1蛋白的表达情况；抑制剂γ-分泌酶抑制Notch信号通路研究对肺癌干细胞增殖及凋亡的影响。结果:利用免疫磁珠分选法分选出肺癌细胞系A549中ALDH1+肺癌干细胞。MTT检测结果显示，姜黄素能够呈浓度依赖性的抑制肺癌干细胞的增殖；经姜黄素处理后的肺癌干细胞，与对照组相比，凋亡率明显升高，Notch1和Hes1蛋白的表达明显下降。经γ-分泌酶抑制剂处理肺癌干细胞后，实验结果显示，γ-分泌酶抑制剂通过下调Notch1和Hes1蛋白的表达调控Notch信号通路抑制肺癌干细胞的增殖，诱导其凋亡。结论:姜黄素抑制肺癌干细胞的增殖，诱导其凋亡与Notch信号通路有关。     

Prognostic impact of cancer stem cell-related markers in non-small cell lung cancer patients treated with induction chemoradiotherapy

The expression of several cancer stem cell (CSC)-related markers has been confirmed in non-small cell lung cancer (NSCLC). The aim of this study was to clarify the clinical role of CSC-related markers in patients with NSCLC undergoing induction chemoradiotherapy (CRT). Fifty patients with clinically diagnosed N2 or N3 NSCLC who underwent induction CRT with docetaxel and cisplatin concurrently with thoracic radiation followed by surgery were examined in this study. The expressions of CSC related markers (CD133, ALDH1, ABCG2, and Bmi-1) were examined using immunohistochemical staining in surgically resected specimens. Among the 50 patients, 20 patients had no residual tumor cells in the resected specimen when examined pathologically; CSC-related marker expressions and their correlation to survival were evaluated in the other 30 patients. After a median follow-up period of 72 months, the 5-year overall survival rate of the patients with CD133-positive or ALDH1-positive specimens was significantly worse than that of the patients with both CD133-negative and ALDH1-negative expressions (44.9% vs. 90.0%, respectively; P = 0.042). In a multivariate analysis, CD133 and ALDH1 negativity (P = 0.047) and cN2-3 single station metastasis (P = 0.03) were significant independent prognostic factors for prolonged survival. The expressions of CSC-related markers after CRT were significantly correlated with a poor prognosis in patients with NSCLC. The development of therapeutic strategies including adjuvant therapy that take CSC-related marker positivity into consideration is likely to be a key factor in further improvements of the prognosis of patients undergoing trimodality therapy.     

Cross-talk between endothelial cells and tumor via delta-like ligand 4/Notch/PTEN signaling inhibits lung cancer growth

Lung cancer is a leading cause of cancer death in many countries. Notch signaling has been demonstrated to frequently participate in the process of lung carcinogenesis. Delta-like ligand 4 (Dll4) is a vascular-specific ligand of Notch, and has a critical role in the angiogenesis of numerous cancers. However, the role of Dll4 in the cross-talk between endothelial cells (ECs) and tumor cells remains obscure. Herein, our study revealed that Dll4-expressing ECs (EC-Dll4) significantly suppressed the proliferation of neighboring non-small cell lung cancer (NSCLC) cells and attenuated the growth of NSCLC xenograft in nude mice. On the contrary, silencing endothelial Dll4 by its specific interference RNA reversed these effects of Dll4 on NSCLC cell proliferation and tumor formation. Furthermore, activation of Notch1, but not Notch2 or Notch3, was enhanced in NSCLC cells cultured with EC-Dll4, as well as in xenografts induced by a mixture of NSCLC cells and EC-Dll4. Interference of Notch1 significantly attenuated Dll4-mediated suppression of NSCLC cell proliferations, indicating that Dll4/Notch1 signaling negatively modulates the NSCLC growth. Moreover, PTEN expression in NSCLC cells was increased by EC-Dll4 or rhDll4 (recombinant human-Dll4 protein), and the induction was impaired by Notch1 interference suggesting that Dll4 could upregulate PTEN expression by Notch1. Taken together, we conclude that the cross-talk between ECs and NSCLC cells by Dll4/Notch1/PTEN signaling pathway inhibits the growth of NSCLC.     

A distinct subpopulation within CD133 positive brain tumor cells shares characteristics with endothelial progenitor cells

The cell surface marker CD133 has been proposed as a brain tumor stem cell marker. However, there have been substantial controversies regarding the necessity and role of CD133 in tumorigenesis. This study aimed to characterize CD133(+) cells in brain tumors. Human brain tumor specimens and whole blood were collected from the same patients (N=12). We carried out dual FACS staining for CD133/CD34 and functional tumorigenesis and angiogenesis analyses of CD133(+) cells from different origins. We also investigated the in vivo tumorigenic potential and histological characteristics of four distinct groups on the basis of expression of CD133/CD34 markers (CD133(+), CD133(+)/CD34(+), CD133(+)/CD34(-), and CD133(-)). CD133(+) brain tumor cells coexpressed significantly higher positivity for CD34 (70.7±5.2% in CD133(+) vs. 12.3±4.2% in CD133(-) cells, P<0.001). CD133(+) brain tumor cells formed neurosphere-like spheroids and differentiated into multiple nervous system lineages unlike CD133(+) blood cells. They showed biological characteristics of endothelial cells, including vWF expression, LDL uptake and tube formation in vitro, unlike CD133(-) brain tumors cells. Pathologic analysis of brains implanted with CD133(+) cells showed large, markedly hypervascular tumors with well-demarcated boundary. CD133(+)/CD34(-) cells produced smaller but highly infiltrative tumors. Notably, pure angiogenic cell fractions (CD133(+)/CD34(+)) and CD133(-) tumor cells did not generate tumors in vivo. Our data suggest the presence of a distinct subpopulation of CD133(+) cells isolated from human brain tumors, with characteristics of endothelial progenitor cells (EPCs).     

STAT3 is necessary for proliferation and survival in colon cancer-initiating cells

STAT3 is constitutively activated in colon cancer but its contributions in cancer-initiating cells have not been explored. In this study, we characterized STAT3 in aldehyde dehydrogenase (ALDH)-positive (ALDH(+)) and CD133-positive (CD133(+)) subpopulations of human colon tumor cells that exhibited more potent tumor-initiating ability than ALDH(-)/CD133(-) cells in tumor xenograft assays in mice. We found that ALDH(+)/CD133(+) cells expressed higher levels of the active phosphorylated form of STAT3 than either ALDH(-)/CD133(-) or unfractionated colon cancer cells. STAT3 inhibition by RNA interference-mediated knockdown or small-molecule inhibitors LLL12 or Stattic blocked downstream target gene expression, cell viability, and tumorsphere-forming capacity in cancer-initiating cells. Similarly, treatment of mouse tumor xenografts with STAT3 short hairpin RNA (shRNA), interleukin 6 shRNA, or LLL12 inhibited tumor growth. Our results establish that STAT3 is constitutively activated in colon cancer-initiating cells and that these cells are sensitive to STAT3 inhibition. These findings establish a powerful rationale to develop STAT3 inhibitory strategies for treating advanced colorectal cancers.     

Circulating tumor cells with a putative stem cell phenotype in peripheral blood of patients with breast cancer

The CD44⁺/CD24^−/low and ALDH1⁺ cell phenotypes are associated with stemness and enhanced tumorigenic potential in breast cancer. We assessed the expression of CD44, CD24 and ALDH1 on tumor cells circulating in the peripheral blood (CTCs) of patients with metastatic breast cancer using triple-marker immunofluorescence microscopy. Among a total of 1439 CTCs identified in 20 (66.7%) out of 30 patients, 35.2% had the stem-like/tumorigenic phenotype CD44⁺/CD24^−/low, whereas 17.7% of the CTCs analyzed in seven patients, were ALDH1^high/CD24^−/low. In conclusion, we report the existence of a subpopulation of CTCs with putative stem cell progenitor phenotypes in patients with metastatic breast cancer.     

CD4+ T cells in cancer stroma, not CD8+ T cells in cancer cell nests, are associated with favorable prognosis in human non-small cell lung cancers

We investigated intratumoral tumor-infiltrating lymphocytes (TILs), including CD4(+) and CD8(+) T cells, in non-small cell lung cancers (NSCLCs) and their relationships with clinicopathological variables and post-operative survival. Tumor specimens from 178 NSCLCs were consecutively obtained by surgery at the Hokkaido University Medical Hospital between 1976 and 1994. CD8(+) T cells, CD4(+) T cells and Ki-67/CD8(+) T cells were visualized immunohistochemically, and counted within cancer cell nests and in cancer stroma. CD8(+) T cells and CD4(+) T cells were observed at higher frequencies within cancer cell nests in moderately and poorly differentiated tumors compared with well differentiated tumors (P < 0.01), and in tumors with high Ki-67 expression compared with low Ki-67 expression (P < 0.01), that showed severe cellular atypia and a higher growth rate. Patients with higher numbers of CD8(+) T cells within cancer cell nests showed significantly shorter survival times compared to those with lower numbers of CD8(+) T cells within cancer cell nests (5-year survival rates, 47% and 60%, respectively; P = 0.03). Moreover, patients with higher labeling index of Ki-67/CD8(+) T cells showed significantly shorter survival than those with lower labeling index of Ki-67/CD8(+) T cells within cancer cell nests (5-year survival rates, 41% and 69%, respectively; P = 0.02), and the labeling index of Ki-67/CD8(+) T cells within cancer cell nests was found to be a significant and independent unfavorable prognostic factor by multivariate analysis (P = 0.01). On the other hand, higher numbers of CD4(+) T cells in cancer stroma, but not within cancer cell nests, were correlated with longer survival times in patients with NSCLC (5-year survival rates, 64% and 43%, respectively; P = 0.04). CD4(+) T cells in cancer stroma might reflect immune responses against cancer cells, while CD8(+) T cells do not appear to work as effectors in tumor tissues of NSCLC. Moreover, the higher labeling index of Ki-67/CD8(+) T cells within cancer cell nests is a strong indicator of unfavorable clinical outcome.     

Characterization of sphere-forming cells with stem-like properties from the small cell lung cancer cell line H446

A relatively novel paradigm in tumor biology hypothesizes that cancer growth is driven by tumor cells with stem-like properties. However, direct proof of a population of stem cells in small cell lung cancer (SCLC) remains elusive. In this study, we enriched for stem-like cells from the SCLC cell line H446 by growing them as spheres in a defined serum-free medium. Sphere-derived cells have increased in vitro clonogenic and in vivo tumorigenic potentials as well as drug-resistant properties. After enrichment for stem-like cells, we used multiple candidate stem cell markers to examine the expression profile and found that the sphere-derived cells contained a higher proportion of cells expressing the stem cell surface markers uPAR and CD133 when compared with parental cells. To identify a selectable marker for the sphere-forming cells, we evaluated the sphere-forming abilities of uPAR(+) and uPAR(-) cells as well as the sphere-forming abilities of CD133(+) and CD133(-) cells. Both CD133(+) and CD133(-) cell fractions were capable of forming spheres, and no statistically significant difference was observed in the sphere-forming efficiency between these two populations. In contrast, cells derived from the uPAR(+) fraction were capable of forming spheres, whereas cells derived from the uPAR(-) fraction remained as single cells. Moreover, uPAR(+) cells efficiently formed transplantable tumors, whereas uPAR(-) cells were unable to initiate tumors when transplanted at equivalent cell numbers. In addition, uPAR(+) cells could differentiate into CD56(+)cells, CK(+) cells, and uPAR(-) cells. These data support the existence of a population of tumor sphere-forming cells with stem cell properties in the H446 SCLC cell line. Furthermore, the stem cell population may be enriched in cells expressing the uPAR cell surface marker.     

CD133 is indicative for a resistance phenotype but does not represent a prognostic marker for survival of non‐small cell lung cancer patients

Despite advances in anticancer treatment, lung cancer still has poor prognosis. Recently, a cancer stem cell (CSC) hypothesis has emerged describing a small subset of tumor cells with stem cell properties. CSCs found in many solid tumors express CD133 antigen on the cell surface. The presence of CSC is correlated with poor survival of patients with glioblastomas, colon or prostate cancers. In this study, we evaluated whether CD133 expression in non‐small cell lung cancer (NSCLC) has a prognostic value in patients' survival. We also analyzed whether CD133 positivity of NSCLC correlates with the expression of resistance‐related proteins, angiogenic factors, oncogenes, proliferative activity or apoptosis. CD133 expression was retrospectively examined in a total of 88 cases of previously untreated NSCLC by immunohistochemistry. We found no correlation between CD133 positivity or the amount of CD133⁺ cells with NSCLC patients' survival, expression of oncogenes c‐myc, c‐N‐ras, c‐jun, c‐fos, c‐erbB1, c‐erbB2 or p53, angiogenic factors VEGF, VEGFR‐1, FGF, FGFR‐1, tissue factor and with proliferative activity or apoptosis in NSCLC tissues. However, there was a significant association between the expression of resistance‐related proteins glutathione S‐transferase, thymidylate synthase, catalase, O⁶‐methylguanine‐DNA methyltransferase and p170 and CD133. Because CD133 expression is linked to a resistant phenotype, detection of CD133⁺ cells may be useful to predict efficacy of cytotoxic therapy but CD133 is not a strong prognostic parameter for survival of patients with NSCLC.     

Cisplatin selects for CD133+cells in lung cancer cells

Objective Platinum-based chemotherapy is the first-line treatment for non-small cell lung cancer,but the chemoresistance of tumor cells continues to be a considerable challenge in the management of NSCLCs,leading to recurrence of most patients.CD133(prominin-1)is a five-transmembrane glycoprotein,and recent evidence suggests that CD133+cells are the cause of drug resistance and tumor recurrence.In this study,the correlation between cisplatin and CD133+cells was investigated systematically.Methods Four lung cancer cell lines,including A549,H460,801D and H1299,were treated with different concentrations of cisplatin.Cell viability was determined by MTT assay.Sphere-forming assay was performed to detect the capability of sphere-forming.CD133+cells was detected by BD FACScaliber flow cytometer.Results The results showed that cisplatin could increase the number of CD133+cells in both time-and dose-dependent manner.The enrichment would weaken but the proportion of CD133+cells was still higher than the basic level as incubation time extended after cisplatin was withdrawn.Compared with adherent culture,the proportion of CD133+cells was higher when the cells were maintained suspension culture.The proportion of CD133+cells significantly increased when cisplatin was provided in suspension culture.Conclusion These results revealed that cisplatin induces the enrichment of CD133+cells and CD133 is a new therapeutic target.Our data partially explained drug resistance to second-line chemotherapy in cisplatin-treated patients with NSCLCs.