Detection of tumor stem cell markers in pancreatic carcinoma cell lines

BACKGROUND: Cancer of the pancreas is the fourth leading cause of cancer death in industrialized countries. In malignancy, actively proliferating cells may be effectively targeted and killed by anti-cancer therapies, but stem cells may survive and support re-growth of the tumor. Thus, new strategies for the treatment of cancer clearly will also have to target cancer stem cells. The goal of the present study was to determine whether pancreatic carcinoma cell growth may be driven by a subpopulation of cancer stem cells. Because previous data implicated ABCG2 and CD133 as stem cell markers in hematopoietic and neural stem/progenitor cells, we analyzed the expression of these two proteins in pancreatic carcinoma cell lines. METHODS: Five established pancreatic adenocarcinoma cell lines were analyzed. Total RNA was isolated and real- time RT-PCR was performed to determine the expression of ABCG2 and CD133. Surface expression of ABCG2 and CD133 was analyzed by flow cytometric analysis. RESULTS: All pancreatic carcinoma cell lines tested expressed significantly higher levels of ABCG2 than non-malignant fibroblasts or two other malignant non- pancreatic cell lines, i.e., SaOS2 osteosarcoma and SKOV3 ovarian cancer. Elevated CD133 expression was found in two out of five pancreatic carcinoma cell lines tested. Using flow cytometric analysis we confirmed surface expression of ABCG2 in all five lines. Yet, CD133 surface expression was detectable in the two cell lines, A818-6 and PancTu1, which exhibited higher mRNA levels.CONCLUSIONS: Two stem cell markers, ABCG2 and CD133 are expressed in pancreatic carcinoma cell lines. ABCG2 and/or CD133 positive cells may represent subpopulation of putative cancer stem cells also in this malignancy. Because cancer stem cells are thought to be responsible for tumor initiation and its recurrence after an initial response to chemotherapy, they may be a very promising target for new drug developments.

Ardisia gigantifolia ethanolic extract inhibits cell proliferation and targets cancer stem cells in gastric cancer

Objective:To evaluate the effects of ethanol extract from Ardisia gigantifolia leaves on cell proliferation and cancer stem cell(CSC)number in gastric cancer.Methods:The inhibitory effect of Ardisia gigantifolia extract on the proliferation of MKN45 and MKN74 gastric cancer cells was assessed using 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide assay.Non-adherent culture(3D)model was used to evaluate the effect of the extract on tumorsphere size and number.Moreover,the expression of CD44,ALDH,and p21 was determined by immunofluorescence analysis.Flow cytometric analysis was performed to evaluate cell cycle arrest and the expression of gastric CSC markers CD44 and ALDH.Real-time PCR analysis was also carried out to assess the effect of the extract on the expression of cell cycle-regulated genes.Results:Ardisia gigantifolia extract effectively inhibited cell proliferation with an IC_(50)of 55.7μg/m L in MKN45 cells and 123.6μg/m L in MKN74 cells.The extract also arrested cell cycle in the G_(0)/G_(1)phase as well as significantly reduced the size and number of tumorspheres.The markedly increased expression of p21 was observed at both m RNA and protein levels in the extract-treated adherent cells and tumorspheres.In addition,Ardisia gigantifolia extract significantly reduced the number of CD44-and/or ALDH-expressing gastric CSC.Conclusions:The development of gastric CSC can be inhibited by the ethanol extract of Ardisia gigantifolia.

Tissue-specific cancer stem/progenitor cells:Therapeutic implications

Surgical resection,chemotherapy,and radiation are the standard therapeutic modalities for treating cancer.These approaches are intended to target the more mature and rapidly dividing cancer cells.However,they spare the relatively quiescent and intrinsically resistant cancer stem cells(CSCs)subpopulation residing within the tumor tissue.Thus,a temporary eradication is achieved and the tumor bulk tends to revert supported by CSCs'resistant features.Based on their unique expression profile,the identification,isolation,and selective targeting of CSCs hold great promise for challenging treatment failure and reducing the risk of cancer recurrence.Yet,targeting CSCs is limited mainly by the irrelevance of the utilized cancer models.A new era of targeted and personalized anti-cancer therapies has been developed with cancer patient-derived organoids(PDOs)as a tool for establishing pre-clinical tumor models.Herein,we discuss the updated and presently available tissue-specific CSC markers in five highly occurring solid tumors.Additionally,we highlight the advantage and relevance of the threedimensional PDOs culture model as a platform for modeling cancer,evaluating the efficacy of CSC-based therapeutics,and predicting drug response in cancer patients.

Methods to produce induced pluripotent stem cell-derived mesenchymal stem cells: Mesenchymal stem cells from induced pluripotent stem cells

Mesenchymal stem cells(MSCs)have received significant attention in recent years due to their large potential for cell therapy.Indeed,they secrete a wide variety of immunomodulatory factors of interest for the treatment of immune-related disorders and inflammatory diseases.MSCs can be extracted from multiple tissues of the human body.However,several factors may restrict their use for clinical applications:the requirement of invasive procedures for their isolation,their limited numbers,and their heterogeneity according to the tissue of origin or donor.In addition,MSCs often present early signs of replicative senescence limiting their expansion in vitro,and their therapeutic capacity in vivo.Due to the clinical potential of MSCs,a considerable number of methods to differentiate induced pluripotent stem cells(iPSCs)into MSCs have emerged.iPSCs represent a new reliable,unlimited source to generate MSCs(MSCs derived from iPSC,iMSCs)from homogeneous and well-characterized cell lines,which would relieve many of the above mentioned technical and biological limitations.Additionally,the use of iPSCs prevents some of the ethical concerns surrounding the use of human embryonic stem cells.In this review,we analyze the main current protocols used to differentiate human iPSCs into MSCs,which we classify into five different categories:MSC Switch,Embryoid Body Formation,Specific Differentiation,Pathway Inhibitor,and Platelet Lysate.We also evaluate common and method-specific culture components and provide a list of positive and negative markers for MSC characterization.Further guidance on material requirements to produce iMSCs with these methods and on the phenotypic features of the iMSCs obtained is added.The information may help researchers identify protocol options to design and/or refine standardized procedures for large-scale production of iMSCs fitting clinical demands.

Biliary tract cancer stem cells-translational options and challenges

Management of biliary tract cancer remains challenging. Tumors show high recurrence rates and therapeutic resistance, leading to dismal prognosis and short survival. The cancer stem cell model states that a tumor is a heterogeneous conglomerate of cells, in which a certain subpopulation of cells-the cancer stem cells-possesses stem cell properties. Cancer stem cells have high clinical relevance due to their potential contributions to development, progression and aggressiveness as well as recurrence and metastasis of malignant tumors. Consequently, reliable identification of as well as pharmacological intervention with cancer stem cells is an intensively investigated and promising research field. The involvement of cancer stem cells in biliary tract cancer is likely as a number of studies demonstrated their existence and the obvious clinical relevance of several established cancer stem cell markers in biliary tract cancer models and tissues. In the present article, we review and discuss the currently available literature addressing the role of putative cancer stem cells in biliary tract cancer as well as the connection between known contributors of biliary tract tumorigenesis such as oncogenic signaling pathways, micro-RNAs and the tumor microenvironment with cancer stem cells.

Doublecortin-like kinase 1 exhibits cancer stem cell-like characteristics in a human colon cancer cell line

Objective： Colon cancer stem cells （CSCs） are implicated in colorectal cancer carcinogenesis, metastasis, and therapeutic resistance. The identification of these cells could help to develop novel therapeutic strategies. Doublecortin-like kinase 1 （DCLK1） has been viewed as a marker for gastrointestinal stem cells that fuel the self-renewal process, however others view them as a marker of Tuft cells or as an enteroendocrine subtype. The purpose of this study was to use a colon cancer cell line to identify and characterize the stem-like characteristics of the DCLKI＋ cell population. Methods： To enrich stem-like cells, HCT116 cells （derived from colon adenocarcinomas） were cultured using serum-free media to form spheres under both normal oxygen and hypoxia condition. DCLK1 transcript expression in the adherent parental cells and spheroids was quantified using quantitative real time reverse transcription- polymerase chain reaction [（q）RT-PCR]. DCLK1 protein expression was determined using flow cytometry. Self-renewal capability from adherent parental cells and spheroids was determined using extreme limiting dilution analysis （ELDA）. Results： Under both normal oxygen and hypoxia condition, the adherent parental cells were composed of cells that express low levels of DCLK1. However, spheroids exhibited an increased frequency of cells expressing DCLK1 on both mRNA and protein levels. Cells derived from spheroids also possess stronger self-renewal capability. Conclusions： The higher fraction of DCLK1 ＋ cells exhibited by spheroids and hypoxia reflects the stem- like characteristics of these cells. DCLK1 may represent an ideal marker to study and develop effective strategies to overcome chemo-resistance and relapse of colon cancer.

ABC transporters,neural stem cells and neurogenesis - a different perspective

Stem cells intrigue. They have the ability to divide exponentially, recreate the stem cell compartment, as well as create differentiated cells to generate tissues. Therefore, they should be natural candidates to provide a renewable source of cells for transplantation applied in regenerative medicine. Stem cells have the capacity to generate specific tissues or even whole organs like the blood, heart, or bones. A subgroup of stem cells, the neural stem cells （NSCs）, is characterized as a self-renewing population that generates neurons and glia of the developing brain. They can be isolated, genetically manipulated and differentiated in vitro and reintroduced into a developing, adult or a pathologically altered central nervous system. NSCs have been considered for use in cell replacement therapies in various neurodegenerative diseases such as Parkinson＇s disease and Alzheimer＇s disease. Characterization of genes with tightly controlled expression patterns during differentiation represents an approach to understanding the regulation of stem cell commitment. The regulation of stem cell biology by the ATP-binding cassette （ABC） transporters has emerged as an important new field of investigation. As a major focus of stem cell research is in the manipulation of cells to enable differentiation into a targeted cell population; in this review, we discuss recent literatures on ABC transporters and stem cells, and propose an integrated view on the role of the ABC transporters, especially ABCA2, ABCA3, ABCB 1 and ABCG2, in NSCs＇ proliferation, differentiation and regulation, along with comparisons to that in hematopoietic and other stem cells.

Reporter gene systems for the identification and characterization of cancer stem cells

Cancer stem cells(CSCs)are tumor cells that share functional characteristics with normal and embryonic stem cells.CSCs have increased tumor-initiating capacity and metastatic potential and lower sensitivity to chemo-and radiotherapy,with important roles in tumor progression and the response to therapy.Thus,a current goal of cancer research is to eliminate CSCs,necessitating an adequate phenotypic and functional characterization of CSCs.Strategies have been developed to identify,enrich,and track CSCs,many of which distinguish CSCs by evaluating the expression of surface markers,the initiation of specific signaling pathways,and the activation of master transcription factors that control stemness in normal cells.We review and discuss the use of reporter gene systems for identifying CSCs.Reporters that are under the control of aldehyde dehydrogenase 1A1,CD133,Notch,Nanog homeobox,Sex-determining region Y-box 2,and POU class 5 homeobox can be used to identify CSCs in many tumor types,track cells in real time,and screen for drugs.Thus,reporter gene systems,in combination with in vitro and in vivo functional assays,can assess changes in the CSCs pool.We present relevant examples of these systems in the evaluation of experimental CSCs-targeting therapeutics,demonstrating their value in CSCs research.

Human dental pulp stem cells express many pluripotency regulators and differentiate into neuronal cells

Stem cells were isolated from human dental pulp using an optimized method, in which pulp pieces were digested by enzymes and immobilized to enhance cell outgrowth. Stem cell marker expression was detected by reverse transcription-PCR （RT-PCR）, and differentiation markers were detected by real-time quantitative RT-PCR and immunocytochemistry. Results showed that dental pulp stem cells actively expressed nanog, oct4, nucleostemin slain-l, jmjdla, jmjd2c, and cyclin DI. When stem cells were induced to differentiate into neurons, nucleostemin, nanog, and cyclin D1 expression significantly decreased, whereas expression of neuronal markers, such as microtubule associated protein-2 and neurofilament-heavy, significantly increased. These results suggested that stem cells exited a pluripotent state and entered a neuronal differentiation pathway. In addition, results demonstrated that human dental pulp serves as a reservoir of stem cells that express defined stem cell markers; these cells were easily isolated and were induced to differentiate towards a desired cell lineage.

Arterial calcification: Finger-pointing at resident and circulating stem cells

The term "Stammzelle"(stem cells) originally appeared in 1868 in the works of Ernst Haeckel who used it to describe the ancestor unicellular organism from which he presumed all multicellular organisms evolved. Since then stem cells have been studied in a wide spectrum of normal and pathological conditions; it is remarkable to note that ectopic arterial calcification was considered a passive deposit of calcium since its original discovering in 1877; in the last decades, resident and circulating stem cells were imaged to drive arterial calcification through chondro-osteogenic differentiation thus opening the idea that an active mechanism could be at the basis of the process that clinically shows a Janus effect: calcifications either lead to the stabilization or rupture of the atherosclerotic plaques. A review of the literature underlines that 130 years after stem cell discovery, antigenic markers of stem cells are still debated and the identification of the osteoprogenitor phenotype is even more elusive due to tissue degradation occurring at processing and manipulation. It is necessary to find a consensus to perform comparable studies that implies phenotypic recognition of stem cells antigens. A hypothesis is based on the singular morphology and amitotic mechanism of division of osteoclasts: it constitutes the opening to a new approach on osteoprogenitors markers and recognition. Our aim was to highlight all the present evidences of the active calcification process, summarize the different cellular types involved, and discuss a novel approach to discover osteoprogenitor phenotypes in arterial wall.

Nestin in gastrointestinal and other cancers: Effects on cells and tumor angiogenesis

Nestin is a class Ⅵ intermediate filament protein that was originally described as a neuronal stem cell marker during central nervous system (CNS) development, and is currently widely used in that capacity. Nestin is also expressed in non-neuronal immature or progenitor cells in normal tissues. Under pathological conditions, nestin is expressed in repair processes in the CNS, muscle, liver, and infarcted myocardium. Furthermore, increased nestin expression has been reported in various tumor cells, including CNS tumors, gastrointestinal stromal tumors, pancreatic cancer, prostate cancer, breast cancer, malignant melanoma, dermatofibrosarcoma protuberances, and thyroid tumors. Nestin is reported to correlate with aggressive growth, metastasis, and poor prognosis in some tumors; however, the roles of nestin in cancer cells have not been well characterized. Furthermore, nestin is more specifically expressed in proliferating small-sized tumor vessels in glioblastoma and gastric, colorectal, and prostate cancers than are other tumor vessel markers. These findings indicate that nestin may be a marker for newly synthesized tumor vessels and a therapeutic target for tumor angiogenesis. It has received a lot of attention recently as a cancer stem cell marker in various cancer cells including brain tumors, malignant rhabdoid tumors, and uterine, cervical, prostate, bladder, head and neck, ovarian, testicular, and pancreatic cancers. The purpose of this review is to clarify the roles of nestin in cancer cells and in tumor angiogenesis, and to examine the association between nestin and cancer stem cells. Nestin has the potential to serve as a molecular target for cancers with nestin-positive cancer cells and nestin-positive tumor vasculature.

Globose basal cells for spinal cord regeneration

Spinal cord injury （SCI） is a devastating condition with loss of motor and sensory functions below the injury level. Cell based therapies are experimented in pre-clinical studies around the world. Neural stem cells are located intra-craniafly in subventricular zone and hippocampus which are highly invasive sourc- es. The olfactory epithelium is a neurogenic tissue where neurogenesis takes place throughout the adult life by a population of stem/progenitor cells. Easily accessible olfactory neuroepithelial stem/progenitor cells are an attractive cell source for transplantation in SCI. Globose basal cells （GBCs） were isolated from rat olfactory epithelium, characterized by flow cytometry and immunohistochemically. These ceils were further studied for neurosphere formation and neuronal induction. T10 laminectomy was done to create drop-weight SCI in rats. On the 9th day following SCI, 5 × 105 cells were transplanted into injured rat spinal cord. The outcome of transplantation was assessed by the Basso, Beattie and Bresnahan （BBB） locomotor rating scale, motor evoked potential and histological observation. GBCs expressed neural stem cell markers nestin, SOX2, NCAM and also mesenchymal stem cell markers （CD29, CD54, CD90, CD73, CD105）. These cells formed neurosphere, a culture characteristics of NSCs and on induction, differentiated cells expressed neuronal markers ~III tubulin, microtubule-associated protein 2, neuronal nuclei, and neurofilament. GBCs transplanted rats exhibited hindlimb motor recovery as confirmed by BBB score and gastrocnemius muscle electromyography amplitude was increased compared to controls. Green fluorescent protein labelled GBCs survived around the injury epicenter and differentiated into βⅢ tubulin-immunoreactive neuron-like cells. GBCs could be an alternative to NSCs from an accessible source for autologous neurotransplantation after SCI without ethical issues.

Therapeutic targets against gastric cancer stem cells interacting with tumor microenvironment

Gastric cancer(GC)is a major cause of cancer-related deaths worldwide.The existe nee of cancer stem cells(CSCs)is known to be the main reas on for resista nee to an ticanceragents as well as for the development of distant metastases.Although CSCs themselves harbor self-renewal and differentiation abilities,the tumor microenvironment that surrounds CSCs provides secreted factors and supports angiogenesis and is thus responsible for the maintenance of their CSC properties.The current review provides information regarding the impact of the tumor microenvironment on gastric CSCs,which will support the development of novel therapeutic strategies for targeting gastric CSCs.

The response of intestinal stem cells and epithelium after alemtuzumab administration

Qiurong Li1,Qiang Zhang1,Chenyang Wang1,Shaojun Jiang2,Ning Li1,Jieshou Li1 Intestinal stem cells may have important roles in the maintenance of epithelial integrity during tissue repair.Alemtuzumab is a humanized anti-CD52 lymphocytic antibody that is increasingly being used to induce immunosuppression;intestinal barrier function is impaired during treatment with alemtuzumab.We investigated the response of intestinal stem cells to epithelial damage resulting from alemtuzumab treatment.Intestinal epithelial cell loss and abnormal Paneth cell morphology were found following a single dose of alemtuzumab.The animals receiving alemtuzumab exhibited increased apoptosis in the villi 3 days after alemtuzumab treatment and in the crypt on day 9,but apoptosis was scarce on day 35.We assessed expression of Musashi-1-and Lgr5-positive stem cells following alemtuzumab treatment.Increased numbers of cells staining positive for both Musashi-1 and Lgr5 were found in the stem cell zone after alemtuzumab treatment for 3 and 9 days.These data indicated that the epithelial cells were injured following alemtuzumab treatment,with the associated expansion of intestinal stem cells.After alemtuzumab treatment for 35 days,the numbers of intestinal epithelial cells and intestinal stem cells returned to normal.This study suggests that alemtuzumab treatment induced the increase in stem cells,resulting in the availability of more enterocytes for repair.

Molecular insights into colorectal cancer stem cell regulation by environmental factors

Colorectal cancer remains a signifi cant cause of cancer-related mortality worldwide,mainly because of tumor relapse and metastases.Cancer stem cells(CSCs)are considered to be the main cause of resistance to chemotherapeutic agents,as well as being responsible for distant metastases.Although CSCs themselves possess innate abilities for self-renewal and differentiation,the environment surrounding CSCs provides oxygen,nutrients and secreted factors,and also supports angiogenesis,thus it's responsible for maintaining their CSC properties.Furthermore,extensive investigations have revealed that obesity,accompanied by excess visceral adipose tissue,induces chronic infl ammation,and is linked to the risk and progression of several gastrointestinal cancers,through modulating the capacities of the CSCs.This review presents the evidence linking colorectal CSCs and their environment and summarizes our current understanding of the molecular mechanisms underlying this relationship.