Isolation Of Cancer Stem-like Cells Research Articles

Abstract PR01: Identification and pharmacological targeting of treatment-resistant, stem-like breast cancer cells for combination therapy

Abstract Marker-based isolation of Cancer Stem-Like Cells (CSLCs), which can display preferential resistance to standard-of-care chemotherapy, has proven challenging, due to their very small frequency in breast cancer tissue, thus impeding their characterization, as well as identification and targeting of mechanistic dependencies. To address this challenge, we leveraged a systems biology framework for the protein-activity based characterization of CSLC biology at the single cell level and for the identification of drugs that could reprogram them to a differentiated, chemotherapy-sensitive state. To enrich for CSLCs we performed flow cytometry-based sorting of cells dissociated from 7 metastatic breast cancer patients, both TNBC and HR+, using the EpCAM and CD49f markers, followed by RNA-seq profiling. Protein activity-based clustering, using the VIPER algorithm (Alvarez et al. Nat Genet 2017), identified complementary cell states associated with high activity of either established CSLC markers (BMI1, NOTCH1, etc.) or markers of differentiated cells (GATA3, KRT18, etc.). VIPER-inferred Master Regulator (MR) proteins, identified by comparing highest versus lowest stemness score cells in each patient, were virtually identical across patients and independent of hormone receptor status. Following MR validation by pooled, CRISPR/Cas9-mediated KO followed by single cell RNA-seq profiling (CROP-seq) in cell lines comprising both CLSC and differentiated BRCA cells, we used the OncoTreat algorithm (Alvarez et al. Nat Genet 2018) to identify small molecule compounds capable of inverting their activity (MR-inverter drugs), thus potentially inducing differentiation or cell death. For this purpose, we leveraged gene expression profiles of BT-20 cells—which significantly recapitulate the CSLC MR signature—following treatment with a repertoire of 91 clinically relevant drugs. Albendazole, the top drug identified by OncoTreat, depleted CSLC population (p = 2.0 × 10−4, by Fisher’s exact test, w.r.t. CSLCs to differentiated cells ratio) without noticeable cytotoxicity in the experiment of single cell-based assays in a TNBC PDX model, at 14 days after treatment. In contrast, paclitaxel, a commonly used chemotherapeutic, significantly increase the ratio of CSLC to differentiated cells (p = 2.6 × 10−4, by Fisher’s exact test), suggesting that alternating treatment with the two drugs may abrogate the tumor-initiating potential of paclitaxel-resistant cells, while also preventing uncontrolled tumor growth. This rationale of combination therapy was confirmed by preclinical study, where treatment with multiple cycles of albendazole and paclitaxel displayed significant synergy (p = 0.00869), compared to the corresponding monotherapies. In conclusion, our systems biology framework is a proof-of-concept that drugs can be effectively repurposed to enhance the therapeutic activity of anti-tumor agents used in conventional chemotherapy, and this method can be generalizable to address the challenge of other cancers with heterogeneity. Citation Format: Jeremy Worley, Heeju Noh, Daoqi You, Mikko M Turunen, Hongxu Ding, Evan Paull, Aaron T Griffin, Adina Grunn, Kristina Guillan, Erin C Bush, Samantha J Brosius, Prabhjot S Mundi, Peter Sims, Piero Dalerba, Filemon S Dela Cruz, Andrew L Kung, Andrea Califano. Identification and pharmacological targeting of treatment-resistant, stem-like breast cancer cells for combination therapy [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Breast Cancer Research; 2023 Oct 19-22; San Diego, California. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_1):Abstract nr PR01.

Abstract 901: Sox2 and Oct4 activity identify CSC populations in ovarian cancer

Abstract High Grade Serous Ovarian Cancer is the most lethal gynecological cancer, mainly due to late-stage diagnosis and prevalence of chemotherapy-resistant disease. Tumors are comprised of heterogenous cancer cells, which makes targeted therapies challenging. Studies have identified a subset of cancer stem-like cells (CSCs) that, unlike bulk tumor cells, can evade chemotherapy and induce relapse. Cell surface markers such as CD133, CD44, CD117, or ALDH enzyme activity are typically used to identify and isolate CSCs; however, these markers are inconsistent across cell lines and patient samples making them unreliable for isolating CSCs. Consistent indicators of CSCs may be activity of stem cell transcription factors, such as SOX2, OCT4, and NANOG, which are known to promote long-term self-renewal and asymmetric division, processes required for tumor repopulation. We hypothesize that a reporter responding to SOX2 and OCT4 activity will represent a functionally relevant and reliable marker for identifying CSCs capable of enabling relapse. We have stably transduced a reporter (termed SORE6), which detects SOX2 and OCT4 activity, into OV90 and ACI23 ovarian cancer cells. SORE6+ cells, isolated using fluorescence assisted cell sorting (FACS), have 2 to 15-fold increases in SOX2/OCT4/NANOG transcripts, relative to SORE6- cells. Comparison of CSC markers in chemotherapy versus vehicle conditions suggests that SORE6 more consistently identifies the CSC population. Specifically, flow cytometry analysis of ACI23 cells showed a 2-fold increase in SORE6+ cells, 7-fold increase in CD117+ cells, and a 1.2-fold increase in CD133 cells in carboplatin treated cells relative to vehicle. For OV90, SORE6+ increases again by 2-fold, while CD117+ increases by 5-fold and CD133 increases by 1.5-fold. SORE6+ cells also showed significantly enhanced spheroid formation efficiency in low serum conditions and resistance to carboplatin and paclitaxel chemotherapies, relative to SORE6- cells. Finally, in vivo limiting dilution studies in mice showed a significant difference in tumorigenicity of SORE6+ cells at low dilutions in ACI23 cells, but not for OV90 cells. Flow cytometry analysis of disassociated tumors showed that tumors created using pure SORE6- cells remained SORE6-, while tumors created using pure SORE6+ cells maintained only 10% SORE6+, indicating the ability of SORE6+ cells to asymmetrically divide to create a heterogeneous tumor. In conclusion, these data suggest that the SORE6 reporter identifies a CSC population within ovarian cancer cell lines and could be a useful tool for consistent isolation of CSCs. Use of this reporter will enhance our understanding of mechanisms, such as SOX2 and OCT4 activity, that support chemoresistance and tumor repopulation. More reliable identification of CSCs will enable the design of therapies to overcome chemotherapy resistance and disease recurrence. Citation Format: Luisjesus S. Cruz, Mikella Robinson, Samuel F. Gilbert, Omar Lujano-Olazaba, Logan A. Alexander, Alex Horkowitz, Carrie D. House. Sox2 and Oct4 activity identify CSC populations in ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 901.

Isolation of cancer stem-like cells from hepatocellular carcinoma cell line HepG2 by methods of magnetic-activated cell sorting, spheroid culture, and anti-tumor drug-resistant selection: A primary evaluation

Introduction: Recently reported data have suggested that only a small subset of cancer cells possess the capability to initiate malignancies. These observations were based on investigation of cells within the primary tumors displaying a distinct surface marker pattern. CD133 marker is a putative hematopoietic and neuronal stem cell marker, which is also considered to be a tumorigenic marker in brain, prostate and liver. Recent studies have shown that a small population of CD133-positive cells, indeed, exists in human hepatocellular carcinoma (HCC) cell lines and primary HCC tissues. This study was aimed at isolating the cancer stem-like cells from hepatocellular carcinoma cell line HepG2 using three different methods: magnetic-activated cell sorting (MACS), spheroid culture (SC), and anti-tumor drug (ATD) resistant selection.
 Methods: HepG2 hepatocellular carcinoma cells were expanded to yield enough cells that could be used to isolate cancer stem-like cells by these three methods. For MACS, cancer stem-like cells were sorted using anti-CD133 monoclonal antibody. For the second method, cancer stem-like cells were enriched by selection of anti-tumor drug resistance property. Lastly, for the third method, three-dimensional (3D) culture was used to enrich for the cancer stem-like cells. The cells obtained by the three methods were expanded to obtain an adequate number of cells for confirmation of CD133 expression.
 Results: The expression of CD133+ cells in the three methods was found to be different. In the MACS method, the expanded CD133+ sorted cells cultured through 2 passages only contained 0.40 % CD133+ cells. In the 3D spheroid cell culture, of the population of cells there were 38.39 % that were CD133+ cells. Lastly, in the anti-tumor drug (doxorubicin at 150 nM) resistant selection, 66.22 % were CD133+ cells.
 Conclusion: This study shows that isolation of HepG2 derived CD133+ population by culture with doxorubicin (150 nM) yields the highest efficiency and purity of the 3 methods studied.

Microfluidic Isolation of Circulating Tumor Cells and Cancer Stem-Like Cells from Patients with Pancreatic Ductal Adenocarcinoma.

Background: Pancreatic ductal adenocarcinoma (PDAC) requires multimodal therapeutic approaches and disease monitoring for effective treatment. Liquid biopsy biomarkers, including circulating tumor cells (CTCs) and cancer stem-like cells (CSCs), hold promise for evaluating treatment response promptly and guiding therapeutic modifications.Methods: From 24 patients with metastatic PDAC (stage IV, M1) undergoing active systemic treatment, we collected 78 blood samples at different time points for CTC and CSC isolation using a microfluidic platform functionalized with antibodies against a CTC biomarker, epithelial cell adhesion molecule (EpCAM), or a CSC biomarker, CD133. These isolated cells were further verified, via fluorescent staining and imaging, using cytokeratin (CK), CD45, and nucleic acid stain 4',6-diamidino-2-phenylindole (DAPI).Results: The majority (84.4%) of patient blood samples were positive for CTCs (EpCAM+CK+CD45-DAPI+) and 70.8% of patient blood samples were positive for CSCs (CD133+CK+CD45-DAPI+), using the highest baseline value of healthy samples as threshold. The CTC subtypes (EpCAM+CK+CD45-DAPI+CD133+ and EpCAM+CK+CD45-DAPI+CD133-) and CSC subtypes (CD133+CK+CD45-DAPI+EpCAM+ and CD133+CK+CD45-DAPI+EpCAM-) were also analyzed using immunochemical methods. In several cases, CSCs exhibited cytokeratin expression that did not express EpCAM, indicating that they will not be detected using EpCAM-based isolation.Conclusion: The microfluidic platform enabled the reliable isolation of CTCs and CSCs from PDAC patient samples, as well as their subtypes. Complementary assessment of both CTCs and CSCs appears advantageous to assess the profile of tumor progressing in some cases. This research has important implications for the application and interpretation of approved methods to detect CTCs.

Development of a novel and economical agar-based non-adherent three-dimensional culture method for enrichment of cancer stem-like cells

BackgroundNon-adherent or ultra-low attachment three-dimensional (3D) culture, also called sphere formation assay, has been widely used to assess the malignant phenotype and stemness potential of transformed or cancer cells. This method is also popularly used to isolate the cancer stem-like cells (CSCs) or tumor-initiating cells based on their unique anchorage-independent growth or anoikis-resistant capacity. Different non-adhesive coating agents, such as poly-2-hydroxyethyl methacrylate (poly-HEMA) and synthetic hydrogels, have been used in this non-adherent 3D culture. However, preparation of non-adherent culture-ware is labor-intensive and technically demanding, and also costs of commercial non-adherent culture-ware prepared with various coating agents are relatively expensive and the culture-ware cannot be used repeatedly.MethodsIn this study, we developed a non-adherent 3D culture method based on agar coating for growing tumor spheres derived from various cancer cell lines and primary prostate cancer tissues under a non-adherent and serum-free condition. The tumor spheres generated by this 3D culture method were analyzed on their expression profiles of CSC-associated markers by reverse transcription quantitative polymerase chain reaction, presence and relative proportion of CSCs by fluorescence-activated cell sorting (CD133+/CD44+ cell sorting) and also a CSC-visualizing reporter system responsive to OCT4 and SOX2 (SORE6), and in vivo tumorigenicity. The repeated use of agar-coated plates for serial passages of tumor spheres was also evaluated.ResultsOur results validated that the multicellular tumor spheres generated by this culture method were enriched of CSCs, as evidenced by their enhanced expression profiles of CSC markers, presence of CD133+/CD44+ or SORE6+ cells, enhanced self-renewal capacity, and in vivo tumorigenicity, indicating its usefulness in isolation and enrichment of CSCs. The agar-coated plates could be used multiple times in serial passages of tumor spheres.ConclusionsThe described agar-based 3D culture method offers several advantages as compared with other methods in isolation of CSCs, including its simplicity and low-cost and repeated use of agar-coated plates for continuous passages of CSC-enriched spheres.

Isolation and characterization of cancer stem-like cells from ACHN renal cancer cells

Objective To isolate and identify stem-like cells (CSCs) from human ACHN renal cell carcinoma cell line. Methods ACHN cancer stem cells CSCs were enriched by serum-free culture condition. Methyl thiazolyl tetrazolium (MTT) method was performed to draw the growth curve. Flow cytometry was performed to evaluate the expressions of two CSCs markers, CD133 and CD44. Real-time polymerase chain reaction (RT-PCR) was performed to evaluate the expression of stem-related genes (Oct3/4, Bmi, Nanog, and β-catenin). The tumorigenicity in vivo was also examined. Results ACHN CSCs were formed by sphere-forming culturing. The data demonstrated that there were stronger capacities of proliferation in ACHN tumor spheres than that of ACHN cells. And the expressions of CD133 and CD44 were also significantly enhanced in tumor spheres. The data showed that four genes (Oct3/4, Bmi, Nanog, and β-catenin) were upregulated in sphere-forming cells. Sphere-forming cells had a higher tumorigenic potential in vivo than incubated cells. Conclusions Human ACHN renal cell carcinoma cell line sphere-forming cells can be enriched by serum-free culture condition and exhibits several characteristic cancer stem cells properties. Key words: Kidney neoplasms; Neoplastic stem cells

Isolation and Characterization of a Head and Neck Squamous Cell Carcinoma Subpopulation Having Stem Cell Characteristics

Despite advances in the understanding of head and neck squamous cell carcinomas (HNSCC) progression, the five-year survival rate remains low due to local recurrence and distant metastasis. One hypothesis to explain this recurrence is the presence of cancer stem-like cells (CSCs) that present inherent chemo- and radio-resistance. In order to develop new therapeutic strategies, it is necessary to have experimental models that validate the effectiveness of targeted treatments and therefore to have reliable methods for the identification and isolation of CSCs. To this end, we present a protocol for the isolation of CSCs from human HNSCC cell lines that relies on the combination of two successive cell sortings performed by fluorescence activated cell sorting (FACS). The first one is based on the property of CSCs to overexpress ATP-Binding Cassette (ABC) transporter proteins and thus exclude, among others, vital DNA dyes such as Hoechst 33342. The cells sorted with this method are identified as a "side population" (SP). As the SP cells represent a low percentage (<5%) of parental cells, a growing phase is necessary in order to increase their number before the second cell sorting. The next step allows for the selection of cells that possess two other HNSCC stem cell characteristics i.e. high expression level of the cell surface marker CD44 (CD44high) and the over-expression of aldehyde dehydrogenase (ALDHhigh). Since the use of a single marker has numerous limitations and pitfalls for the isolation of CSCs, the combination of SP, CD44 and ALDH markers will provide a useful tool to isolate CSCs for further analytical and functional assays requiring viable cells. The stem-like characteristics of CSCs was finally validated in vitro by the formation of tumorispheres and the expression of β-catenin.

Isolation and Characterization of a Head and Neck Squamous Cell Carcinoma Subpopulation Having Stem Cell Characteristics.

Despite advances in the understanding of head and neck squamous cell carcinomas (HNSCC) progression, the five-year survival rate remains low due to local recurrence and distant metastasis. One hypothesis to explain this recurrence is the presence of cancer stem-like cells (CSCs) that present inherent chemo- and radio-resistance. In order to develop new therapeutic strategies, it is necessary to have experimental models that validate the effectiveness of targeted treatments and therefore to have reliable methods for the identification and isolation of CSCs. To this end, we present a protocol for the isolation of CSCs from human HNSCC cell lines that relies on the combination of two successive cell sortings performed by fluorescence activated cell sorting (FACS). The first one is based on the property of CSCs to overexpress ATP-Binding Cassette (ABC) transporter proteins and thus exclude, among others, vital DNA dyes such as Hoechst 33342. The cells sorted with this method are identified as a "side population" (SP). As the SP cells represent a low percentage (<5%) of parental cells, a growing phase is necessary in order to increase their number before the second cell sorting. The next step allows for the selection of cells that possess two other HNSCC stem cell characteristics i.e. high expression level of the cell surface marker CD44 (CD44(high)) and the over-expression of aldehyde dehydrogenase (ALDH(high)). Since the use of a single marker has numerous limitations and pitfalls for the isolation of CSCs, the combination of SP, CD44 and ALDH markers will provide a useful tool to isolate CSCs for further analytical and functional assays requiring viable cells. The stem-like characteristics of CSCs was finally validated in vitro by the formation of tumorispheres and the expression of β-catenin.

CD133-positive cancer stem cells from Colo205 human colon adenocarcinoma cell line show resistance to chemotherapy and display a specific metabolomic profile.

During the past decade, cancer stem-like cells (CSCs) have drawn substantial interest in cancer research since they have been described as major targets to improve treatment of tumors and to prevent recurrence and metastasis. In this paper, we report on the search for CSCs within the Colo205 human adenocarcinoma cell line. We describe that CD133 (prominin) was the only reliable marker for the isolation and characterization of CSCs within a Colo205 cell population. CD133-positive cells displayed many CSC characteristics, such as tumorsphere formation ability, expression of early-stage development markers, high invasiveness, raised tumor initiation potential and resistance to cisplatin chemotherapy treatment. In vitro analyses also highlighted a specific metabolomic profile of CD133-positive cells and we concluded that the chemotherapy resistance of CSCs could be related to the quiescence of such cells associated with their reduced metabolism. Furthermore, in vivo metabolome analyses suggested that a high level of circulating glutathione molecules could also promote treatment resistance. From the perspective of metabolomics, we also discuss the controversial use of serum-free in vitro cultures for CSC enrichment prior to further phenotype characterization.

Isolation and identification of lung cancer stem-like cells based on a 3D cell culture system

Isolation and identification of lung cancer stem-like cells based on a 3D cell culture system

CD44 and SSEA-4 positive cells in an oral cancer cell line HSC-4 possess cancer stem-like cell characteristics

Cancer may be derived from cancer stem-like cells (CSCs), which are tumor-initiating cells that have properties similar to those of stem cells. Identification and isolation of CSCs needs to be improved further. CSCs markers were examined in human oral cancer cell lines by flow cytometry. The stem cell properties of subpopulations expressing different markers were assessed further by in vitro sphere formation assays, expression of stemness genes, drug resistance assays, and the ability to form tumors in nude mice. We demonstrated that CSCs could be isolated by the cell surface markers CD44 and stage-specific embryonic antigen-4 (SSEA-4). CD44+SSEA-4+ cells exhibited cancer stem-like properties, including extensive self-renewal into the bulk of cancer cells. In vivo xenograft experiments indicated that CD44+SSEA-4+ cells exhibit the highest tumorigenic capacity compared with the remaining subpopulations and parental cells. Double-positive cells for CD44 and SSEA-4 exhibited preferential expression of some stemness genes and were more resistant to the anticancer drugs, cisplatin and 5-fluorouracil (5-FU). In addition, cells expressing CD44 and SSEA-4 were detected in all tumor specimens analyzed, while coexpression of CD44 and SSEA-4 was not detectable in normal oral mucosa. Our findings suggest that CD44+SSEA-4+ cells exhibit the characteristics of CSCs in oral squamous cell carcinoma and provide a target for the development of more effective therapies.

Cytometry in stem cell research and therapy

recent Nobel Prize in medicine was awarded to two stemcell researchers, John Gurdon and Shinya Yamanaka, for theirachievements in stem cell research and reprogramming ofsomatic cells. Flow cytometry is by nature the ideal tool toidentify, characterize, and isolate stem and progenitor cells forresearch and potential clinical use (1). The major strength offlow cytometry is its ability to rapidly perform highlymultiplexed quantitative measurements on single cells withina heterogeneous cell population. However, when the cell typeof interest is extremely rare, as most stem and progenitor cellsare, several sources of artifact must be addressed. The impor-tance of flow cytometry as a driving force for stem cellresearch was demonstrated in a focused issue of the journalexactly three years ago (1). This current focus issue of Cytome-try A is devoted to the topic of stem cells due to numerouscurrent innovations and discoveries.Applications of stem cells include several disciplines,from embryogenesis, adult tissue maintenance, and repair,and more recently, cancer as well as for toxicity screening anddisease modeling. All of these topics are represented in thisissue, with special emphasis on the role of analytic and pre-parative flow cytometry in the elucidation of stem cell pheno-type and function, and best laboratory practices as they applyto flow cytometry. Image and flow cytometry together withcell sorting have revolutionized the study of stem cell biologyand the implications of these cells and their progeny indevelopmental biology, tissue engineering, and cellulartherapy. The number of parameters and the speed of theirsimultaneous measurements in single cells has continued toincrease with advances in hardware, reagents, and analyticalsoftware (2).

Abstract 4185: Isolation of cancer stem-like cells from a novel orthotopic xenograt model of supratentorial primitive neuroectodermal tumor that is susceptible to oncolytic Seneca Valley Virus

Abstract Purpose: Supratentorial primitive neuroectodermal tumor (PNET) accounts for 2-3% of all pediatric brain tumors. Despite multimodality therapies, the clinical outcome remains poor, and the 5-year progression free survival rate is less than 40%. Clinically relevant animal models are needed for understanding tumor biology and developing more effective therapies. Here we report our recent development of a clinically relevant animal model, isolation and characterization of cancer stem-like cells in the xenograft tumors, and preclinical investigation of the antitumor efficacy of a novel picorna oncolytic virus Seneca Valley Virus-001 (SVV-001) both in vitro and vivo, especially in cancer stem-like cells. Experimental Design: Orthotopic xenograft mouse model was developed by direct injection of 105 tumor cells from a freshly resected brain PNET tumor specimen into the right cerebrum of Rag2/severe combined immunodeficient mice. CD133+ cells were quantitatively analyzed and isolated with FACS using human-specific antibodies against CD133. Antitumor activity of SVV-001was evaluated in vitro in cultured xenograft tumor cells and in vivo in mice bearing pre-formed xenograft tumors. Results: A novel transplantable PNET xenograft model IC-2664PNT was established. The xenograft tumors not only replicate the biologic phenotypes but also preserve cancer stem-like cell pools. The IC-2664PNET neurospheres, which expressed high levels of CD133 and nestin, were efficiently infected and killed by SVV-001 (0.5-25 virus particle/ cell). A single tail vein injection of SVV-001 (5×1012 virus particle/kg) prolonged survival time of PNET xenograft model. Conclusions: We have established the first clinically relevant animal model for childhood supratentorial PNET. It replicated the major histopathological features of the original patient tumor, and preserved a CD133+ stem cells pool during serial subtransplantations. SVV-001 has potent antitumor efficacy in PNET, especially selectively kill cancer stem-like cells, and prolong survival in vivo. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4185.

Isolation of cancer stem-like cells from a side population of a human glioblastoma cell line, SK-MG-1

Accumulating evidence suggests that in several types of brain tumors, including glioma, only a phenotypic subset of tumor cells called brain cancer stem cells (BCSCs) may be capable of initiating tumor growth. Recently, the isolation of side population (SP) cells using Hoechst dye has become a useful method for obtaining cancer stem cells in various tumors. In this study, we isolated cancer stem-like cells from human glioma cell lines using the SP technique. Flow cytometry analysis revealed that SK-MG-1, a human glioblastoma cell line, contained the largest number of SP cells among the five glioma cell lines that were analyzed. The SP cells had a self-renewal ability and were capable of forming spheres in a neurosphere culture medium containing EGF and FGF2. Spheres derived from the SP cells differentiated into three different lineage cells: neurons, astrocytes and oligodendrocytes. RT-PCR analysis revealed that the SP cells expressed a neural stem cell marker, Nestin. The SP cells generated tumors in the brains of NOD/SCID mice at 8 weeks after implantation, whereas the non-SP cells did not generate any tumors in the brain. These results indicate that SP cells isolated from SK-MG-1 possess the properties of cancer stem cells, including their self-renewal ability, multi-lineage differentiation, and tumorigenicity. Therefore, the SP cells from SK-MG-1 may be useful for analyzing BCSCs because of the ease with which they can be handled and their yield.

Replacing Hoechst33342 with Rhodamine123 in isolation of cancer stem-like cells from the MHCC97 cell line

The side population (SP) is commonly applied to analyzing cancer stem cells (CSCs) biology. However, the Hoechst33342 (Hoechst) dye, which is used for SP isolation, is demonstrated to be toxic to cells. The aim of this study was to identify a dye that might replace or offer an alternative to Hoechst use. In the trial group, by FACS binding Rhodamine123 (Rho), Rho low (low Rho fluorescence) and Rho high (high Rho fluorescence) were sorted from the MHCC97 cell line. In the control group, SP (low Hoechst fluorescence) and NSP (high Hoechst fluorescence) were obtained through Hoechst/FACS. The percentages of subpopulations were as following: Rho low 2.1%, Rho high 97.9%, SP 1.4%, NSP 98.6%. The proliferative abilities in vitro (growth rate, soft agar clone formation rate), expressions of stem cell markers (early hepatic marker AFP and CSCs marker CD133), and tumorigenicities in vivo were significantly higher in the Rho low and SP cells than those in the Rho high and NSP cells, respectively ( P < 0.05). In addition, each result was the same between the Rho low and SP cells ( P > 0.05). Taken together, Rho/FACS may not be as effective as Hoechst/FACS for CSCs sorting, but given its low toxicity and cost, it may be a useful method for CSCs identification.

Isolation and identiffcation of cancer stem-like side population cells in pancreatic cancer

Objective To isolate and identify side population(SP)cells in pancreatic cancer.Methods We detected the number of SP cells in 5 pancreatic cancer cell lines and 3 clinical samples by Hoechst33342 dyeing and FACS analysis.The clone formation efficiency and tumorigenicity were compared between SP cels and non-SP ceils by clone formation assay and NOD/SCID xenograft transplantation experiment.The differentiation ability of SP ceils was studied by flow cytometry reanalysis of SP-derived tumors and cultured SP ceils.Results All cell lines and clinical samples were found to exhibit verapamilsensitive SP cells except BXPC-3.Using SP cells sorted from PANC-1 as a model.SP ceUs were demonstratcd to exhibit higher colony-formation ability than non-SP cells [(43.67±3.10)% vs (8.33±1.63)%.P＜0.01].And flow cytometry reanalysis indicated SP ceHs could generate both SP and non-SP cells with a fraction size comparable with the original population.In addition.SP cells were enriched in tumorigenicity by at least 100-fold compared with non-SP cells.and had the capacity to generate nontumorigenic non-SP cells through asymmetrical cell division in vivo.Conclusion SP phenotype iS a potential marker for pancreatic cancer stem cells. Key words: Pancreatic carcinoma; Tumor stem cells; Identifieation