Detection of CD133 (prominin-1) in a human hepatoblastoma cell line (HuH-6 clone 5)

Co-Expression of CD34, CD90, OV-6 and Cell-Surface Vimentin Defines Cancer Stem Cells of Hepatoblastoma, Which Are Affected by Hsp90 Inhibitor 17-AAG

Cancer stem cells (CSCs) are nowadays one of the major focuses in tumor research since this subpopulation was revealed to be a great obstacle for successful treatment. The identification of CSCs in pediatric solid tumors harbors major challenges because of the immature character of these tumors. Here, we present CD34, CD90, OV-6 and cell-surface vimentin (csVimentin) as reliable markers to identify CSCs in hepatoblastoma cell lines. We were able to identify CSC characteristics for the subset of CD34⁺CD90⁺OV-6⁺csVimentin⁺-co-expressing cells, such as pluripotency, self-renewal, increased expression of EMT markers and migration. Treatment with Cisplatin as the standard chemotherapeutic drug in hepatoblastoma therapy further revealed the chemo-resistance of this subset, which is a main characteristic of CSCs. When we treated the cells with the Hsp90 inhibitor 17-AAG, we observed a significant reduction in the CSC subset. With our study, we identified CSCs of hepatoblastoma using CD34, CD90, OV-6 and csVimentin. This set of markers could be helpful to estimate the success of novel therapeutic approaches, as resistant CSCs are responsible for tumor relapses.

Shift in the function of netrin-1 from axon outgrowth to axon branching in developing cerebral cortical neurons

BACKGROUND

Netrin-1, a multifunctional axon guidance cue, elicits axon outgrowth via one of its receptors deleted in colorectal cancer (DCC) in several types of neurons, including cerebral cortical neurons of embryonic mice. However, we and others have observed de novo formation of axon branches without axon outgrowth induced by netrin-1 in cortical culture of neonatal hamsters. These previous reports suggested the possibility that netrin-1 function might alter during development, which we here investigated using dissociated culture prepared from cerebral cortices of embryonic mice.

RESULTS

Imaging analysis revealed netrin-1-induced outgrowth in embryonic day (E) 14 axons and netrin-1-induced branching in E16 axons. Netrin-1-evoked filopodial protrusions, which sprouted on the shafts of E16 axons preceding branch formation, were visualized by a novel method called atmospheric scanning electron microscopy. Treatment with an anti-DCC function-blocking antibody affected both axon outgrowth and branching.

CONCLUSIONS

Morphological analyses suggested a possibility of a shift in the function of netrin-1 in cortical axons during development, from promotion of outgrowth to promotion of branch formation starting with filopodial protrusion. Function-blocking experiments suggested that DCC may contribute not only to axon outgrowth but branching.

Lovastatin Decreases the Expression of CD133 and Influences the Differentiation Potential of Human Embryonic Stem Cells

The lipophilic statin lovastatin decreases cholesterol synthesis and is a safe and effective treatment for the prevention of cardiovascular diseases. Growing evidence points at antitumor potential of lovastatin. Therefore, understanding the molecular mechanism of lovastatin function in different cell types is critical to effective therapy design. In this study, we investigated the effects of lovastatin on the differentiation potential of human embryonic stem (hES) cells (H9 cell line). Multiparameter flow cytometric assay was used to detect changes in the expression of transcription factors characteristic of hES cells. We found that lovastatin treatment delayed NANOG downregulation during ectodermal and endodermal differentiation. Likewise, expression of ectodermal (SOX1 and OTX2) and endodermal (GATA4 and FOXA2) markers was higher in treated cells. Exposure of hES cells to lovastatin led to a minor decrease in the expression of SSEA-3 and a significant reduction in CD133 expression. Treated cells also formed fewer embryoid bodies than control cells. By analyzing hES with and without CD133, we discovered that CD133 expression is required for proper formation of embryoid bodies. In conclusion, lovastatin reduced the heterogeneity of hES cells and impaired their differentiation potential.

Optimized dissociation protocol for isolating human glioma stem cells from tumorspheres via fluorescence-activated cell sorting

Fluorescence-activated cell sorting (FACS) based on the surface marker CD133 is the most common method for isolating glioma stem cells (GSCs) from heterogeneous glioma cell populations. Optimization of this method will have profound implications for the future of GSC research. Five commonly used digestion reagents, Liberase-TL, trypsin, TrypLE, Accutase, and non-enzymatic cell dissociation solution (NECDS), were used to dissociate glioma tumorspheres derived from two primary glioma specimens (091214 and 090116) and the cell lines U87 and T98G. The dissociation time, cell viability, retention of CD133, and stemness capacity were assessed. The results showed that single cells derived from the Liberase-TL (200 µg/ml) group exhibited high viability and less damage to the antigen CD133. However, the efficiency of NECDS for dissociating the tumorspheres into single cells was fairly low. Meanwhile, the use of this digestion reagent resulted in obvious cellular and antigenic impairments. Taken together, Liberase-TL (200 µg/ml) is an ideal reagent for isolating GSCs from tumorspheres. In contrast, the use of NECDS for such a protocol should be carefully considered.

Aldehyde Dehydrogenase 1 (ALDH1) Is a Potential Marker for Cancer Stem Cells in Embryonal Rhabdomyosarcoma

Cancer stem cells (CSCs) are defined as a small population of cancer cells with the properties of high self-renewal, differentiation, and tumor-initiating functions. Recent studies have demonstrated that aldehyde dehydrogenase 1 (ALDH1) is a marker for CSCs in adult cancers. Although CSCs have been identified in some different types of pediatric solid tumors, there have been no studies regarding the efficacy of ALDH1 as a marker for CSCs. Therefore, in order to elucidate whether ALDH1 can be used as a marker for CSCs of pediatric sarcoma, we examined the characteristics of a population of cells with a high ALDH1 activity (ALDH1high cells) in rhabdomyosarcoma (RMS), the most common soft tissue sarcoma in children. We used the human embryonal RMS (eRMS) cell lines RD and KYM-1, and sorted the cells into two subpopulations of ALDH1high cells and cells with a low ALDH1 activity (ALDH1low cells). Consequently, we found that the ALDH1high cells comprised 3.9% and 8.2% of the total cell population, respectively, and showed a higher capacity for self-renewal and tumor formation than the ALDH1low cells. With regard to chemoresistance, the survival rate of the ALDH1high cells was found to be higher than that of the ALDH1low cells following treatment with chemotherapeutic agents for RMS. Furthermore, the ALDH1high cells exhibited a higher degree of pluripotency and gene expression of Sox2, which is one of the stem cell markers. Taken together, the ALDH1high cells possessed characteristics of CSCs, including colony formation, chemoresistance, differentiation and tumor initiation abilities. These results suggest that ALDH1 is a potentially useful marker of CSCs in eRMS.

Aberrant expression of cancer stem cell markers (CD44, CD90, and CD133) contributes to disease progression and reduced survival in hepatoblastoma patients: 4-year survival data

Hepatoblastoma (HB) is an embryonal tumor of the liver in children. Prognosis and response to treatment in HB are highly variable. Cancer stem cells (CSCs) constitute a population of cells, which contribute to the development and progression of many tumors. However, their role in HB is not well defined yet. We assessed the prognostic and predictive values of some CSC markers in HB patients. Protein and messenger RNA expressions of the CSC markers CD133, CD90, and CD44 were assessed in 43 HB patients and 20 normal hepatic tissues using immunohistochemistry and quantitative real-time polymerase chain reaction. The expression levels of these markers were correlated to standard prognostic factors, patients' response to treatment, overall survival (OS), and disease-free survival (DFS). CD44, CD90, and CD133 proteins were detected in 48.8%, 32.6%, and 48.8% compared with 46.5%, 41.7%, and 58.1% RNA, respectively (concordance, 77.8%-96%). None of the normal tissue samples was positive for any of the markers. Significant correlations were reported between α-fetoprotein and both CD44 and CD133 (P = 0.02) as well as between tumor types CD90 and CD133 (P = 0.009). Reduced OS correlated with CD44, CD90, and CD133 expressions (P < 0.001), advanced stage (P < 0.001), response to treatment (P < 0.001), and total excision of the tumor. Reduced DFS correlated with CD44 and CD133 expressions (P < 0.001) only. In conclusion, CD133, CD44, and CD90 could be used as prognostic and predictive markers in HB. High expression of these markers is significantly associated with poor response to treatment and reduced survival. Moreover, complete surgical resection and systemic chemotherapy are essential to achieve good response and prolonged survival, especially in early stage patients.

Observation of tissues in open aqueous solution by atmospheric scanning electron microscopy: applicability to intraoperative cancer diagnosis

In the atmospheric scanning electron microscope (ASEM), a 2- to 3-μm layer of the sample resting on a silicon nitride-film window in the base of an open sample dish is imaged, in liquid, at atmospheric pressure, from below by an inverted SEM. Thus, the time-consuming pretreatments generally required for biological samples to withstand the vacuum of a standard electron microscope are avoided. In the present study, various mouse tissues (brain, spinal cord, muscle, heart, lung, liver, kidney, spleen and stomach) were fixed, stained with heavy metals, and visualized in radical scavenger D-glucose solution using the ASEM. While some stains made the nuclei of cells very prominent (platinum-blue, phosphotungstic acid), others also emphasized cell organelles and membranous structures (uranium acetate or the NCMIR method). Notably, symbiotic bacteria were sometimes observed on stomach mucosa. Furthermore, kidney tissue could be stained and successfully imaged in <30 min. Lung and spinal cord tissue from normal mice and mice metastasized with breast cancer cells was also examined. Cancer cells present in lung alveoli and in parts of the spine tissue clearly had larger nuclei than normal cells. The results indicate that the ASEM has the potential to accelerate intraoperative cancer diagnosis, the diagnosis of kidney diseases and pathogen detection. Importantly, in the course of the present study it was possible to increase the observable tissue area by using a new multi-windowed ASEM sample dish and sliding the tissue across its eight windows.

Immuno-electron microscopy of primary cell cultures from genetically modified animals in liquid by atmospheric scanning electron microscopy

High-throughput immuno-electron microscopy is required to capture the protein-protein interactions realizing physiological functions. Atmospheric scanning electron microscopy (ASEM) allows in situ correlative light and electron microscopy of samples in liquid in an open atmospheric environment. Cells are cultured in a few milliliters of medium directly in the ASEM dish, which can be coated and transferred to an incubator as required. Here, cells were imaged by optical or fluorescence microscopy, and at high resolution by gold-labeled immuno-ASEM, sometimes with additional metal staining. Axonal partitioning of neurons was correlated with specific cytoskeletal structures, including microtubules, using primary-culture neurons from wild type Drosophila, and the involvement of ankyrin in the formation of the intra-axonal segmentation boundary was studied using neurons from an ankyrin-deficient mutant. Rubella virus replication producing anti-double-stranded RNA was captured at the host cell's plasma membrane. Fas receptosome formation was associated with clathrin internalization near the surface of primitive endoderm cells. Positively charged Nanogold clearly revealed the cell outlines of primitive endoderm cells, and the cell division of lactic acid bacteria. Based on these experiments, ASEM promises to allow the study of protein interactions in various complexes in a natural environment of aqueous liquid in the near future.

Multidrug resistance and cancer stem cells in neuroblastoma and hepatoblastoma

Chemotherapy is one of the major modalities in treating cancers. However, its effectiveness is limited by the acquisition of multidrug resistance (MDR). Several mechanisms could explain the up-regulation of MDR genes/proteins in cancer after chemotherapy. It is known that cancer stem cells (CSCs) play a role as master regulators. Therefore, understanding the mechanisms that regulate some traits of CSCs may help design efficient strategies to overcome chemoresistance. Different CSC phenotypes have been identified, including those found in some pediatric malignancies. As solid tumors in children significantly differ from those observed in adults, this review aims at providing an overview of the mechanistic relationship between MDR and CSCs in common solid tumors, and, in particular, focuses on clinical as well as experimental evidence of the relations between CSCs and MDR in neuroblastoma and hepatoblastoma. Finally, some novel approaches, such as concomitant targeting of multiple key transcription factors governing the stemness of CSCs, as well as nanoparticle-based approaches will also be briefly addressed.

Detection of the Hematopoietic Stem and Progenitor Cell Marker CD133 during Angiogenesis in Three-Dimensional Collagen Gel Culture

We detected the hematopoietic stem and progenitor cell marker CD133 using immunogold labeling during angiogenesis in a three-dimensional collagen gel culture. CD133-positive cells were present in capillary tubes newly formed from aortic explants in vitro. The CD133-positive cell population had the capacity to form capillary tubes. Lovastatin strongly inhibited cell migration from aortic explants and caused the degradation of the capillary tubes. The present study provides insight into the function of CD133 during angiogenesis as well as an explanation for the antiangiogenic effect of statins.