MicroRNAs (miRNAs) are small non-coding RNAs that regulate messenger RNAs at the post-transcriptional level. They play an important role in the control of cell physiological functions, and their alterations have been related to cancer, where they can function as oncogenes or tumor suppressor genes. Recently, they have emerged as key regulators of "stemness", collaborating in the maintenance of pluripotency, control of self-renewal, and differen-tiation of stem cells. The miRNA pathway has been shown to be crucial in embryonic development and in embryonic stem (ES) cells, as shown by Dicer knockout analysis. Specific patterns of miRNAs have been reported to be expressed only in ES cells and in early phases of embryonic development. Moreover, many cancers present small populations of cells with stem cell characteristics, called cancer stem cells (CSCs). CSCs are responsible for relapse and treatment failure in many cancer patients, and the comparative analysis of expression patterns between ES cells and tumors can lead to the identification of a miRNA signature to define CSCs. Most of the key miRNAs identified to date in ES cells have been shown to play a role in tumor diagnosis or prognosis, and may well prove to be essential in cancer therapy in the foreseeable future.
Embryonic Stem Cells/cytology/*metabolism ; Humans ; MicroRNAs/genetics/*metabolism ; Models, Biological ; Neoplastic Stem Cells/cytology/*metabolism ; Signal Transduction/genetics/*physiology

As pioneer of tumor stem cell research, leukemia stem cell research has not only important theoretical significance, but also clinical application potential. The survival and development of stem cells are directly impacted by their microenvironment. The research on leukemia stem cells and their microenvironment are now becoming a hot topic. The author presumes that stem cells are a population with heterogenecity and hierarchy; any single cell from the population is difficult to form a clone; the interaction between the leukemia stem cell and its microenvironment can be described by the concept of leukemia stem cell niche. In this article, the leukemia cell population with heterogenecity and hierarchy as well as leukemia stem cell niche were summarized and discussed.
Cell Line, Tumor ; Humans ; Leukemia ; genetics ; pathology ; Neoplastic Stem Cells ; metabolism ; pathology ; Stem Cell Niche ; cytology ; Stromal Cells ; cytology ; immunology

Actins ; metabolism ; Breast ; cytology ; metabolism ; Breast Neoplasms ; metabolism ; pathology ; Cell Differentiation ; Female ; Humans ; Keratins ; metabolism ; Neoplastic Stem Cells ; metabolism ; pathology ; Signal Transduction ; Stem Cells ; cytology ; metabolism

Stem cells use asymmetric and symmetric cell division to generate progeny. Symmetric cell division is defined as the generation of daughter cells that are destined to acquire the same fate. Stem cells divide asymmetrically to generate one daughter with a stem-cell fate and one daughter with different fate. Disruption of the machinery that regulates asymmetric division may be a reason for the generation of cancer. The asymmetric mechanism is maintained by cell polarity factors, cell fate determinants, and the spindle apparatus. The mutation or dysregulation of these factors may change stem cells from asymmetric to symmetric cell division, then leading to tumorigenesis. Therefore, further study is needed on the mechanisms of stem cell control between asymmetric and symmetric cell division, as well as the relationships among stem cells, cancer stem cells, and tumor cells. It may bring us a new approach for the resistance, recurrence, and metastasis of tumors.
Animals ; Cell Division ; physiology ; Cell Polarity ; Cell Transformation, Neoplastic ; Drosophila ; cytology ; Humans ; Neoplasms ; pathology ; Neoplastic Stem Cells ; pathology ; Neurons ; cytology ; Spindle Apparatus ; metabolism ; Tumor Suppressor Proteins ; metabolism

The aim of this study was to detect the presence of human AML leukemia stem cells (LSC) in childhood patients with acute leukemia (AL) and analyze the correlation between LSC concentrations and minimal residual disease (MRD) levels in AML cases after remission. The multi-parameter flow cytometry (FCM) and a panel of monoclonal antibody combination were used to detect the AML LSC or AML LSC immunophenotype-identical cell (AML LSC-IPIC) concentrations in childhood AML or ALL leukemia both at new diagnosis and at remission and correlated AML LSC to the MRD levels at different time points after remission. The results indicated that the AML LSC or AML LSC-IPIC concentrations [in average 166 (range 14 - 1459)/100 000 mononuclear cells (MNCs)] in AML at initial diagnosis were significantly higher than those in ALL [7 (range 0 - 560)/100 000 MNCs, p < 0.017] and control [0 (range 0 - 6)/100 000 MNCs, p < 0.017], respectively. The AML LSC concentrations in AML at non-CR were in average 36 (range 5 - 224)/100 000 MNCs. No statistical difference (p > 0.05) was found between the AML LSC or AML LSC-IPIC concentrations in AML (in average 6 (range 0 - 41)/100, 000 MNCs) and ALL [10 (range 0 - 105)/100, 000 MNCs] after CR. The significantly negative correlation was noticed between AML LSC concentrations and MRD levels. It is concluded that the AML LSCs exist in newly diagnosed AML, which are significantly reduced when complete remission has achieved, but the low levels of these populations still remain. The phenotypically similar (CD34(+)CD38⁻CD123(+)) AML LSC populations have also been found in the bone marrow from ALL patients, but their concentrations are not significantly different when CR has achieved. The significantly negative correlation between AML LSC concentrations and MRD levels is observed in AML patients after remission.
Adolescent ; Child ; Child, Preschool ; Female ; Flow Cytometry ; Humans ; Immunophenotyping ; Leukemia, Myeloid, Acute ; immunology ; metabolism ; Male ; Neoplasm, Residual ; immunology ; metabolism ; Neoplastic Stem Cells ; cytology ; Tumor Stem Cell Assay

Stem cells and progenitor cells are the cells of origin for multi-cellular organisms and organs. They play key roles during development and their dysregulation gives rise to human diseases such as cancer. The recent development of induced pluripotent stem cell (iPSC) technology which converts somatic cells to stem-like cells holds great promise for regenerative medicine. Nevertheless, the understanding of proliferation, differentiation, and self-renewal of stem cells and organ-specific progenitor cells is far from clear. Recently, the Hippo pathway was demonstrated to play important roles in these processes. The Hippo pathway is a newly established signaling pathway with critical functions in limiting organ size and suppressing tumorigenesis. This pathway was first found to inhibit cell proliferation and promote apoptosis, therefore regulating cell number and organ size in both Drosophila and mammals. However, in several organs, disturbance of the pathway leads to specific expansion of the progenitor cell compartment and manipulation of the pathway in embryonic stem cells strongly affects their self-renewal and differentiation. In this review, we summarize current observations on roles of the Hippo pathway in different types of stem cells and discuss how these findings changed our view on the Hippo pathway in organ development and tumorigenesis.
Animals ; Cell Differentiation ; Cell Proliferation ; Drosophila ; Drosophila Proteins ; metabolism ; Humans ; Intracellular Signaling Peptides and Proteins ; metabolism ; Mesenchymal Stem Cells ; cytology ; metabolism ; Neoplastic Stem Cells ; cytology ; metabolism ; Nuclear Proteins ; metabolism ; Protein-Serine-Threonine Kinases ; metabolism ; Signal Transduction ; Stem Cells ; cytology ; metabolism ; Transcription Factors ; metabolism

BACKGROUND AND OBJECTIVEDetection of label retaining cells (LRCs) has been a method to confirm existence of stem cells, and bromodeoxyuridine (BrdU) has commonly been used for labeling. In this study, to verify stem cells in nasopharyngeal carcinoma (NPC), LRCs were established and detected in NPC cell line 5-8F.

METHODSThe 5-8F cells were cultured with BrdU and inoculated subcutaneously into nude mice. By immunohistochemistry, immunocytochemistry, and immunofluorescence, BrdU was detected in 5-8F cells and xenograft tumors.

RESULTSBrdU was strongly positive in cells on the 2nd and the 7th day after being added BrdU, while negative when cells were cultured without BrdU. However, only sporadic cells were positive on the 14th day after BrdU being washed out, and these cells were thought to be LRCs. The average percentage of LRCs was (0.67 +/- 0.32)%. After being cultivated with BrdU for 48 h, 5-8F cells were inoculated into nude mice subcutaneously. After chasing 8 weeks, only sporadic LRCs were detected in xenograft tumors, with a proportion of (0.55 +/- 0.36)%, and these LRCs were located at cancer margin.

CONCLUSIONThe existence of LRCs in 5-8F cells indicates the existence of cancer stem cells in NPC.

Animals ; Bromodeoxyuridine ; metabolism ; Cell Line, Tumor ; Female ; Humans ; Mice ; Mice, Inbred BALB C ; Mice, Nude ; Nasopharyngeal Neoplasms ; metabolism ; pathology ; Neoplasm Transplantation ; Neoplastic Stem Cells ; cytology ; metabolism

OBJECTIVETo investigate the role of bone morphogenetic protein 4 (BMP4) on the proliferation and apoptosis in glioma stem cells.

METHODSStem cells were isolated from a human glioma cell line U87 by using vincristine and characterized by immunofluorescence assay. Proliferation and apoptosis were determined by soft agar colony assay and flow cytometry; Cyclin D1, Bcl-2 and Bax were detected by Western blot analysis.

RESULTSBMP4 inhibited cell proliferation and promoted apoptosis in U87 glioma stem cells. Moreover, Bcl-2 and Cyclin D1 expression were decreased by BMP4, while Bax level was elevated.

CONCLUSIONBMP4 can inhibit U87 glioma stem cells proliferation through downregulating Cyclin D1 level, and promote apoptosis through induction of Bax expression and inhibition of Bcl-2 level. It suggests that BMP4 plays an important role in human glioma stem cell biology.

Apoptosis ; Bone Morphogenetic Protein 4 ; genetics ; metabolism ; Cell Line, Tumor ; Cell Proliferation ; Cyclin D1 ; genetics ; metabolism ; Gene Expression Regulation, Neoplastic ; Glioma ; genetics ; metabolism ; physiopathology ; Humans ; Neoplastic Stem Cells ; cytology ; metabolism ; Proto-Oncogene Proteins c-bcl-2 ; genetics ; metabolism

Tumor stem/progenitor cells are the cells with the characteristics of self-renewal, differentiating to all the other cell populations within tumor, which are also regarded as the source of tumor relapse, drug-resistance and metastasis. As a subtype of acute myeloid leukemia, acute promyelocytic leukemia (APL) represents the target of therapy due to the good response of the oncogenic protein PML-RARα to all-trans retinoic acid (ATRA) and arsenic trioxide (ATO). This review summarizes the latest research results of APL as follows: (1) there probably are two APL stem/progenitor cell populations within APL, and self-renewal and survival of APL stem/progenitor cells highly depend on PML-RARα expression, cell cycle inhibitor p21, self-renewal associated molecules and chemokines; and (2) ATRA and ATO eradicate APL stem/progenitor cells mainly by PML-RARα degradation, FOXO3A activation and the inhibition of self-renewal-associated signaling pathway of sonic hedgehog. These findings are helpful to improve other tumor therapy.
Cell Survival ; Cyclin-Dependent Kinase Inhibitor p21 ; Humans ; Leukemia, Promyelocytic, Acute ; metabolism ; pathology ; Neoplastic Stem Cells ; cytology ; Oncogene Proteins, Fusion ; Signal Transduction ; Tumor Cells, Cultured

OBJECTIVETo isolate and culture tumor stem cells from glioma tissues obtained at surgical operation and to study their biological characteristics.

METHODSGlioma tissues obtained from surgically resected specimens of 8 patients were fully chopped, trypsinized, and filtered to prepare single cell suspensions. The cells were cultured in serum-free medium with EGF, LIF and bFGF. CD133(+) cells were purified by magnetic cell sorting, and cultured continuously in vitro to obtain tumor cell spheres. Tumor stem cells of the 5th passage were induced to differentiate with 10% FBS, and expression of cell differentiation markers such as Nestin, MAP2, GFAP was evaluated with immunocytochemistry techniques.

RESULTSCD133(+) cells were successfully separated and cultured from one anasplastic mixed astrocyte-ependymocyte type glioma specimen. These cells maintained a sphere-like growth status in vitro (3 months, 14 passages), and can self-renew, proliferate and conditionally differentiate into MAP2(+) and GFAP(+) cells. However, CD133(-) cells did not possess these properties.

CONCLUSIONGlioma tissue contains tumor stem cells. Those cells can be cultured and passaged in vitro for a long term, and therefore to offer new approaches for studying cellular and molecular biology of glioma.

AC133 Antigen ; Antigens, CD ; metabolism ; Brain Neoplasms ; pathology ; Cell Differentiation ; Cell Proliferation ; Cell Separation ; Cells, Cultured ; Glial Fibrillary Acidic Protein ; metabolism ; Glioma ; pathology ; Glycoproteins ; metabolism ; Humans ; Microtubule-Associated Proteins ; metabolism ; Neoplastic Stem Cells ; cytology ; metabolism ; Peptides ; metabolism