More than just proliferation: Myc function in stem cells

Functional significance of earthworm clitellum in regulating the various biological aspects of cell survival and regeneration

Earthworms are a highly abundant species in nature, with nearly 7000 different species being discovered. Despite the similarities in morphology among earthworm species, their regeneration capabilities vary based on the clitellum. The clitellum plays a crucial role in the clitellum-dependent worms, as it is involved in the processes of regeneration and reproduction in earthworms. The fascinating characteristic of the clitellum, which serves as a hub for stem cells in clitellum-dependent worms, plays a crucial role in various biological processes that require further exploration. This review focuses on the overall physiological functions and uncovers the lesser-known roles of the clitellum that have been documented in various research articles. In recent times, numerous studies have been conducted using the earthworm model to explore various areas. In that regard, the clitellum's different roles in regulating and controlling stem cells, the regeneration process, regulation of organogenesis, stress response, aging, autotomy, and various features have been briefly discussed. Ultimately, we emphasized the unique and versatile role of the clitellum in the animal model, making it an ideal choice for studying development, regeneration, stem cells, organogenesis, toxicology, autotomy, and aging response.

Suberanilohydroxamic acid (SAHA), a HDAC inhibitor, suppresses the effect of Treg cells by targeting the c-Myc/CCL1 pathway in glioma stem cells and improves PD-L1 blockade therapy

PURPOSE

A strong immunosuppressive tumor microenvironment (TME) represents the major barrier responsible for the failure of current immunotherapy approaches in treating Glioblastoma Multiforme (GBM). Within the TME, the regulatory T cells (Tregs) exert immunosuppressive effects on CD8+ T cell - mediated anti-cancer immune killing. Consequently, targeting and inhibiting their immunosuppressive function emerges as an effective therapeutic strategy for GBM. The present study aimed to investigate the mechanisms and effects of Suberanilohydroxamic Acid (SAHA), a histone deacetylase inhibitor, on immunosuppressive Tregs.

METHODS

The tumor-infiltrating immune cells in the immunocompetent GBM intracranial implanted xenograft mouse model were analyzed by immunohistochemistry and flow cytometry techniques. The mRNA expressions were assessed through the RT-qPCR method, while the related protein expressions were determined using western blot, ELISA, immunofluorescence (IF), and flow cytometry techniques. The relationship between c-Myc and C-C motif Chemokine Ligand 1 (CCL1) promotor was validated through a dual-luciferase reporter assay system and chromatin immunoprecipitation.

RESULTS

SAHA suppressed effectively tumor growth and extended significantly overall survival in the immunocompetent GBM intracranial xenograft mouse model. Additionally, it promoted the infiltration of CD8+ T lymphocytes while suppressed the infiltration of CD4+ CD25+ Tregs. Furthermore, SAHA enhanced anti-PD-L1 immune therapy in the intracranial xenograft of mice. Mechanistically, SAHA exerted its effects by inhibiting histone deacetylase 2 (HDAC2), thereby suppressing the binding between c-Myc and the CCL1 promotor.

CONCLUSION

SAHA inhibited the binding of c-Myc with the CCL1 promoter and then suppressed the transcription of CCL1.Additionally, it effectively blocked the interplay of CCL1-CCR8, resulting in reduced activity of Tregs and alleviation of tumor immunosuppression.

Brd4::Nutm1 fusion gene initiates NUT carcinoma in vivo

NUT carcinoma (NC) is an aggressive cancer with no effective treatment. About 70% of NUT carcinoma is associated with chromosome translocation events that lead to the formation of a BRD4::NUTM1 fusion gene. Because the BRD4::NUTM1 gene is unequivocally cytotoxic when ectopically expressed in cell lines, questions remain on whether the fusion gene can initiate NC. Here, we report the first genetically engineered mouse model for NUT carcinoma that recapitulates the human t(15;19) chromosome translocation in mice. We demonstrated that the mouse t(2;17) syntenic chromosome translocation, forming the Brd4::Nutm1 fusion gene, could induce aggressive carcinomas in mice. The tumors present histopathological and molecular features similar to human NC, with enrichment of undifferentiated cells. Similar to the reports of human NC incidence, Brd4::Nutm1 can induce NC from a broad range of tissues with a strong phenotypical variability. The consistent induction of poorly differentiated carcinoma demonstrated a strong reprogramming activity of BRD4::NUTM1. The new mouse model provided a critical preclinical model for NC that will lead to better understanding and therapy development for NC.

KBTBD4-mediated reduction of MYC is critical for hematopoietic stem cell expansion upon UM171 treatment

ABSTRACT

Ex vivo expansion of hematopoietic stem cells (HSCs) is gaining importance for cell and gene therapy, and requires a shift from dormancy state to activation and cycling. However, abnormal or excessive HSC activation results in reduced self-renewal ability and increased propensity for myeloid-biased differentiation. We now report that activation of the E3 ligase complex CRL3KBTBD4 by UM171 not only induces epigenetic changes through CoREST1 degradation but also controls chromatin-bound master regulator of cell cycle entry and proliferative metabolism (MYC) levels to prevent excessive activation and maintain lympho-myeloid potential of expanded populations. Furthermore, reconstitution activity and multipotency of UM171-treated HSCs are specifically compromised when MYC levels are experimentally increased despite degradation of CoREST1.

Tespa1 facilitates hematopoietic and leukemic stem cell maintenance by restricting c-Myc degradation

Hematopoietic stem cells (HSCs) and leukemia stem cells (LSCs) have robust self-renewal potential, which is responsible for sustaining normal and malignant hematopoiesis, respectively. Although considerable efforts have been made to explore the regulation of HSC and LSC maintenance, the underlying molecular mechanism remains obscure. Here, we observe that the expression of thymocyte-expressed, positive selection-associated 1 (Tespa1) is markedly increased in HSCs after stresses exposure. Of note, deletion of Tespa1 results in short-term expansion but long-term exhaustion of HSCs in mice under stress conditions due to impaired quiescence. Mechanistically, Tespa1 can interact with CSN subunit 6 (CSN6), a subunit of COP9 signalosome, to prevent ubiquitination-mediated degradation of c-Myc protein in HSCs. As a consequence, forcing c-Myc expression improves the functional defect of Tespa1-null HSCs. On the other hand, Tespa1 is identified to be highly enriched in human acute myeloid leukemia (AML) cells and is essential for AML cell growth. Furthermore, using MLL-AF9-induced AML model, we find that Tespa1 deficiency suppresses leukemogenesis and LSC maintenance. In summary, our findings reveal the important role of Tespa1 in promoting HSC and LSC maintenance and therefore provide new insights on the feasibility of hematopoietic regeneration and AML treatment.

E3 ubiquitin ligase on the biological properties of hematopoietic stem cell

Hematopoietic stem cells are a group of heterogeneity cells with the potential to differentiate into various types of mature blood cells. Their basic biological properties include quiescence, self-renewal, multilineage differentiation, and homing ability, with the homing of exogenous hematopoietic stem cells after transplantation becoming a new focus, while the first three properties share some similarity in mechanism due to connectivity. In various complex mechanisms, the role of E3 ubiquitin ligases in hematopoietic homeostasis and malignant transformation is receiving increasing attention. As a unique part, E3 ubiquitin ligases play an important role in physiological regulation mechanism of posttranslational modification. In this review, we focus on the recent progress of the crucial role of E3 ubiquitin ligases that target specific proteins for ubiquitination to regulate biological properties of hematopoietic stem cells. Additionally, this paper deals with E3 ubiquitin ligases that affect the biological properties through aging and summarizes the relevant applications of targeting E3 ligases in hematopoietic malignancies. We present some ideas on the clinical application of E3 ubiquitin ligase to regulate hematopoietic stem cells and also believe that it is meaningful to study the upstream signal of these E3 ubiquitin ligases because hematopoietic stem cell dysfunction is caused by deficiency of some E3 ligases.

A MYC-ZNF148-ID1/3 regulatory axis modulating cancer stem cell traits in aggressive breast cancer

The MYC proto-oncogene (MYC) is one of the most frequently overexpressed genes in breast cancer that drives cancer stem cell-like traits, resulting in aggressive disease progression and poor prognosis. In this study, we identified zinc finger transcription factor 148 (ZNF148, also called Zfp148 and ZBP-89) as a direct target of MYC. ZNF148 suppressed cell proliferation and migration and was transcriptionally repressed by MYC in breast cancer. Depletion of ZNF148 by short hairpin RNA (shRNA) and CRISPR/Cas9 increased triple-negative breast cancer (TNBC) cell proliferation and migration. Global transcriptome and chromatin occupancy analyses of ZNF148 revealed a central role in inhibiting cancer cell de-differentiation and migration. Mechanistically, we identified the Inhibitor of DNA binding 1 and 3 (ID1, ID3), drivers of cancer stemness and plasticity, as previously uncharacterized targets of transcriptional repression by ZNF148. Silencing of ZNF148 increased the stemness and tumorigenicity in TNBC cells. These findings uncover a previously unknown tumor suppressor role for ZNF148, and a transcriptional regulatory circuitry encompassing MYC, ZNF148, and ID1/3 in driving cancer stem cell traits in aggressive breast cancer.

MTBP and MYC: A Dynamic Duo in Proliferation, Cancer, and Aging

The oncogenic transcription factor c-MYC (MYC) is highly conserved across species and is frequently overexpressed or dysregulated in human cancers. MYC regulates a wide range of critical cellular and oncogenic activities including proliferation, metabolism, metastasis, apoptosis, and differentiation by transcriptionally activating or repressing the expression of a large number of genes. This activity of MYC is not carried out in isolation, instead relying on its association with a myriad of protein cofactors. We determined that MDM Two Binding Protein (MTBP) indirectly binds MYC and is a novel MYC transcriptional cofactor. MTBP promotes MYC-mediated transcriptional activity, proliferation, and cellular transformation by binding in a protein complex with MYC at MYC-bound promoters. This discovery provided critical context for data linking MTBP to aging as well as a rapidly expanding body of evidence demonstrating MTBP is overexpressed in many human malignancies, is often linked to poor patient outcomes, and is necessary for cancer cell survival. As such, MTBP represents a novel and potentially broad reaching oncologic drug target, particularly when MYC is dysregulated. Here we have reviewed the discovery of MTBP and the initial controversy with its function as well as its associations with proliferation, MYC, DNA replication, aging, and human cancer.

Proliferative and anti‐apoptotic fractions in maturing hematopoietic cell lineages and their role in homeostasis of normal bone marrow

Recent developments in clinical flow cytometry allow the simultaneous assessment of proliferative and anti‐apoptotic activity in the different hematopoietic cell lineages and during their maturation process. This can further advance the flow cytometric diagnosis of myeloid malignancies. In this study we established indicative reference values for the Ki‐67 proliferation index and Bcl‐2 anti‐apoptotic index in blast cells, as well as maturing erythroid, myeloid, and monocytic cells from normal bone marrow (BM). Furthermore, the cell fractions co‐expressing both proliferation and anti‐apoptotic markers were quantified. Fifty BM aspirates from femoral heads of patients undergoing hip replacement were included in this study. Ten‐color/twelve‐parameter flow cytometry in combination with a software‐based maturation tool was used for immunophenotypic analysis of Ki‐67 and Bcl‐2 positive fractions during the erythro‐, myelo‐, and monopoiesis. Indicative reference values for the Ki‐67 and Bcl‐2 positive fractions were established for different relevant hematopoietic cell populations in healthy BM. Ki‐67 and Bcl‐2 were equally expressed in the total CD34 positive blast cell compartment and 30% of Ki‐67 positive blast cells also showed Bcl‐2 positivity. The Ki‐67 and Bcl‐2 positive fractions were highest in the more immature erythroid, myeloid and monocytic cells. Both fractions then gradually declined during the subsequent maturation phases of these cell lineages. We present a novel application of an earlier developed assay that allows the simultaneous determination of the Ki‐67 proliferative and Bcl‐2 anti‐apoptotic indices in maturing hematopoietic cell populations of the BM. Their differential expression levels during the maturation process were in accordance with the demand and lifespan of these cell populations. The indicative reference values established in this study can act as a baseline for further cell biological and biomedical studies involving hematological malignancies.

Genetic barcoding systematically comparing genes in del(5q) MDS reveals a central role for CSNK1A1 in clonal expansion

Csnk1a1 haploinsufficient hematopoietic stem cells outcompete other key genes in del(5q) MDS in direct competitive transplantation.

Chronic inflammatory stress increases the competitive advantage of Csnk1a1 haploinsufficient hematopoietic stem cells.

How genetic haploinsufficiency contributes to the clonal dominance of hematopoietic stem cells (HSCs) in del(5q) myelodysplastic syndrome (MDS) remains unresolved. Using a genetic barcoding strategy, we performed a systematic comparison on genes implicated in the pathogenesis of del(5q) MDS in direct competition with each other and wild-type (WT) cells with single-clone resolution. Csnk1a1 haploinsufficient HSCs expanded (oligo)clonally and outcompeted all other tested genes and combinations. Csnk1a1^−/+ multipotent progenitors showed a proproliferative gene signature and HSCs showed a downregulation of inflammatory signaling/immune response. In validation experiments, Csnk1a1^−/+ HSCs outperformed their WT counterparts under a chronic inflammation stimulus, also known to be caused by neighboring genes on chromosome 5. We therefore propose a crucial role for Csnk1a1 haploinsufficiency in the selective advantage of 5q-HSCs, implemented by creation of a unique competitive advantage through increased HSC self-renewal and proliferation capacity, as well as increased fitness under inflammatory stress.

Hydroquinone 5-O-Cinnamoyl Ester of Renieramycin M Suppresses Lung Cancer Stem Cells by Targeting Akt and Destabilizes c-Myc

Cancer stem cells (CSCs) are distinct cancer populations with tumorigenic and self-renewal abilities. CSCs are drivers of cancer initiation, progression, therapeutic failure, and disease recurrence. Thereby, novel compounds targeting CSCs offer a promising way to control cancer. In this study, the hydroquinone 5-O-cinnamoyl ester of renieramycin M (CIN-RM) was demonstrated to suppress lung cancer CSCs. CIN-RM was toxic to lung cancer cells with a half-maximal inhibitory concentration of around 15 µM. CIN-RM suppressed CSCs by inhibiting colony and tumor spheroid formation. In addition, the CSC population was isolated and treated and the CSCs were dispatched in response to CIN-RM within 24 h. CIN-RM was shown to abolish cellular c-Myc, a central survival and stem cell regulatory protein, with the depletion of CSC markers and stem cell transcription factors ALDH1A1, Oct4, Nanog, and Sox2. For up-stream regulation, we found that CIN-RM significantly inhibited Akt and consequently decreased the pluripotent transcription factors. CIN-RM also inhibited mTOR, while slightly decreasing p-GSK3β (Ser9) but rarely affected the protein kinase C (PKC) signal. Inhibiting Akt/mTOR induced ubiquitination of c-Myc and promoted degradation. The mechanism of how Akt regulates the stability of c-Myc was validated with the Akt inhibitor wortmannin. The computational analysis further confirmed the strong interaction between CIN-RM and the Akt protein with a binding affinity of −10.9 kcal/mol at its critical active site. Taken together, we utilized molecular experiments, the CSC phenotype, and molecular docking methods to reveal the novel suppressing the activity of this compound on CSCs to benefit CSC-targeted therapy for lung cancer treatment.

The Involvement of Macrophage Colony Stimulating Factor on Protein Hydrolysate Injection Mediated Hematopoietic Function Improvement

Protein hydrolysate injection (PH) is a sterile solution of hydrolyzed protein and sorbitol that contains 17 amino acids and has a molecular mass of 185.0-622.0 g/mol. This study investigated the effect of PH on hematopoietic function in K562 cells and mice with cyclophosphamide (CTX)-induced hematopoietic dysfunction. In these myelosuppressed mice, PH increased the number of hematopoietic cells in the bone marrow (BM) and regulated the concentration of several factors related to hematopoietic function. PH restored peripheral blood cell concentrations and increased the numbers of hematopoietic stem cells and progenitor cells (HSPCs), B lymphocytes, macrophages, and granulocytes in the BM of CTX-treated mice. Moreover, PH regulated the concentrations of macrophage colony stimulating factor (M-CSF), interleukin (IL)-2, and other hematopoiesis-related cytokines in the serum, spleen, femoral condyle, and sternum. In K562 cells, the PH-induced upregulation of hematopoiesis-related proteins was inhibited by transfection with M-CSF siRNA. Therefore, PH might benefit the BM hematopoietic system via the regulation of M-CSF expression, suggesting a potential role for PH in the treatment of hematopoietic dysfunction caused by cancer therapy.

Role of c-Myc haploinsufficiency in the maintenance of HSCs in mice

This study was conducted to determine the dosage effect of c-Myc on hematopoiesis and its distinct role in mediating the Wnt/β-catenin pathway in hematopoietic stem cell (HSC) and bone marrow niche cells. c-Myc haploinsufficiency led to ineffective hematopoiesis by inhibiting HSC self-renewal and quiescence and by promoting apoptosis. We have identified Nr4a1, Nr4a2, and Jmjd3, which are critical for the maintenance of HSC functions, as previously unrecognized downstream targets of c-Myc in HSCs. c-Myc directly binds to the promoter regions of Nr4a1, Nr4a2, and Jmjd3 and regulates their expression. Our results revealed that Nr4a1 and Nr4a2 mediates the function of c-Myc in regulating HSC quiescence, whereas all 3 genes contribute to the function of c-Myc in the maintenance of HSC survival. Adenomatous polyposis coli (Apc) is a negative regulator of the Wnt/β-catenin pathway. We have provided the first evidence that Apc haploinsufficiency induces a blockage of erythroid lineage differentiation through promoting secretion of IL6 in bone marrow endothelial cells. We found that c-Myc haploinsufficiency failed to rescue defective function of Apc-deficient HSCs in vivo but it was sufficient to prevent the development of severe anemia in Apc-heterozygous mice and to significantly prolong the survival of those mice. Furthermore, we showed that c-Myc-mediated Apc loss induced IL6 secretion in endothelial cells, and c-Myc haploinsufficiency reversed the negative effect of Apc-deficient endothelial cells on erythroid cell differentiation. Our studies indicate that c-Myc has a context-dependent role in mediating the function of Apc in hematopoiesis.

Targeting the Mevalonate Pathway in Cancer

The mevalonate synthesis inhibitors, statins, are mainstay therapeutics for cholesterol management and cardiovascular health. Thirty years of research have uncovered supportive roles for the mevalonate pathway in numerous cellular processes that support oncogenesis, most recently macropinocytosis. Central to the diverse mechanisms of statin sensitivity is an acquired dependence on one mevalonate pathway output, protein geranylgeranylation. New chemical prenylation probes and the discovery of a novel geranylgeranyl transferase hold promise to deepen our understanding of statin mechanisms of action. Further, insights into statin selection and the counterproductive role of dietary geranylgeraniol highlight how we should assess statins in the clinic. Lastly, rational combination strategies preview how statins will enter the oncology toolbox.

Awakening the HSC: Dynamic Modeling of HSC Maintenance Unravels Regulation of the TP53 Pathway and Quiescence

Hematopoietic stem cells (HSCs) provide all types of blood cells during the entire life of the organism. HSCs are mainly quiescent and can eventually enter the cell cycle to differentiate. HSCs are maintained and tightly regulated in a particular environment. The stem cell niche regulates dormancy and awakening. Deregulations of this interplay can lead to hematopoietic failure and diseases. In this paper, we present a Boolean network model that recapitulates HSC regulation in virtue of external signals coming from the niche. This Boolean network integrates and summarizes the current knowledge of HSC regulation and is based on extensive literature research. Furthermore, dynamic simulations suggest a novel systemic regulation of TP53 in homeostasis. Thereby, our model indicates that TP53 activity is balanced depending on external stimulations, engaging a regulatory mechanism involving ROS regulators and RAS activated transcription factors. Finally, we investigated different mouse models and compared them to in silico knockout simulations. Here, the model could recapitulate in vivo observed behaviors and thus sustains our results.

Constructing temporal regulatory cascades in the context of development and cell differentiation

Cell differentiation is a complex process orchestrated by sets of regulators precisely appearing at certain time points, resulting in regulatory cascades that affect the expression of broader sets of genes, ending up in the formation of different tissues and organ parts. The identification of stage-specific master regulators and the mechanism by which they activate each other is a key to understanding and controlling differentiation, particularly in the fields of tissue regeneration and organoid engineering. Here we present a workflow that combines a comprehensive general regulatory network based on binding site predictions with user-provided temporal gene expression data, to generate a a temporally connected series of stage-specific regulatory networks, which we call a temporal regulatory cascade (TRC). A TRC identifies those regulators that are unique for each time point, resulting in a cascade that shows the emergence of these regulators and regulatory interactions across time. The model was implemented in the form of a user-friendly, visual web-tool, that requires no expert knowledge in programming or statistics, making it directly usable for life scientists. In addition to generating TRCs the tool links multiple interactive visual workflows, in which a user can track and investigate further different regulators, target genes, and interactions, directing the tool along the way into biologically sensible results based on the given dataset. We applied the TRC model on two different expression datasets, one based on experiments conducted on human induced pluripotent stem cells (hiPSCs) undergoing differentiation into mature cardiomyocytes and the other based on the differentiation of H1-derived human neuronal precursor cells. The model was successful in identifying previously known and new potential key regulators, in addition to the particular time points with which these regulators are associated, in cardiac and neural development.

Synergic pro-apoptotic effects of Ferulic Acid and nanostructured lipid carrier in glioblastoma cells assessed through molecular and Delayed Luminescence studies

Herein, we assessed the effect of Ferulic Acid (FA), a natural antioxidant with anti-cancer effect, on the human glioblastoma cells through molecular and Delayed Luminescence (DL) studies. DL, a phenomenon of ultra-week emission of optical photons, was used to monitor mitochondrial assessment. The effect of FA loaded in nanostructured lipid carriers (NLCs) was also assessed. To validate NLCs as a drug delivery system for glioblastoma treatment, particular attention was focused on their effect. We found that free FA induced a significant decrease in c-Myc and Bcl-2 expression levels accompanied by the apoptotic pathway activation. Blank NLCs, even if they did not induce cytotoxicity and caspase-3 cleavage, decreased Bcl-2, ERK1/2, c-Myc expression levels activating PARP-1 cleavage. The changes in DL intensity and kinetics highlighted a possible effect of nanoparticle matrix on mitochondria, through the involvement of the NADH pool and ROS production that, in turn, activates ERK1/2 pathways. All the effects on protein expression levels and on the activation of apoptotic pathway appeared more evident when the cells were exposed to FA loaded in NLCs. We demonstrated that the observed effects are due to a synergic pro-apoptotic influence exerted by FA, whose bio-availability increases in the glioblastoma cells, and NLCs formulation.

Hemmule: A Novel Structure with the Properties of the Stem Cell Niche

Stem cells are nurtured and regulated by a specialized microenvironment known as stem cell niche. While the functions of the niches are well defined, their structure and location remain unclear. We have identified, in rat bone marrow, the seat of hematopoietic stem cells—extensively vascularized node-like compartments that fit the requirements for stem cell niche and that we called hemmules. Hemmules are round or oval structures of about one millimeter in diameter that are surrounded by a fine capsule, have afferent and efferent vessels, are filled with the extracellular matrix and mesenchymal, hematopoietic, endothelial stem cells, and contain cells of the megakaryocyte family, which are known for homeostatic quiescence and contribution to the bone marrow environment. We propose that hemmules are the long sought hematopoietic stem cell niches and that they are prototypical of stem cell niches in other organs.

MDA-9/Syntenin (SDCBP) Is a Critical Regulator of Chemoresistance, Survival and Stemness in Prostate Cancer Stem Cells

Despite some progress, treating advanced prostate cancer remains a major clinical challenge. Recent studies have shown that prostate cancer can originate from undifferentiated, rare, stem cell-like populations within the heterogeneous tumor mass, which play seminal roles in tumor formation, maintenance of tumor homeostasis and initiation of metastases. These cells possess enhanced propensity toward chemoresistance and may serve as a prognostic factor for prostate cancer recurrence. Despite extensive studies, selective targeted therapies against these stem cell-like populations are limited and more detailed experiments are required to develop novel targeted therapeutics. We now show that MDA-9/Syntenin/SDCBP (MDA-9) is a critical regulator of survival, stemness and chemoresistance in prostate cancer stem cells (PCSCs). MDA-9 regulates the expression of multiple stem-regulatory genes and loss of MDA-9 causes a complete collapse of the stem-regulatory network in PCSCs. Loss of MDA-9 also sensitizes PCSCs to multiple chemotherapeutics with different modes of action, such as docetaxel and trichostatin-A, suggesting that MDA-9 may regulate multiple drug resistance. Mechanistically, MDA-9-mediated multiple drug resistance, stemness and survival are regulated in PCSCs through activation of STAT3. Activated STAT3 regulates chemoresistance in PCSCs through protective autophagy as well as regulation of MDR1 on the surface of the PCSCs. We now demonstrate that MDA-9 is a critical regulator of PCSC survival and stemness via exploiting the inter-connected STAT3 and c-myc pathways.

c-Myc Inhibitor 10074-G5 Induces Murine and Human Hematopoietic Stem and Progenitor Cell Expansion and HDR Modulator Rad51 Expression

Background:

c-Myc plays a major role in the maintenance of glycolytic metabolism and hematopoietic stem cell (HSC) quiescence.

Objective:

Targeting modulators of HSC quiescence and metabolism could lead to HSC cell cycle entry with concomitant expansion.

Methods and Results:

Here we show that c-Myc inhibitor 10074-G5 treatment leads to 2-fold increase in murine LSKCD34low HSC compartment post 7 days. In addition, c-Myc inhibition increases CD34+ and CD133+ human HSC number. c-Myc inhibition leads to downregulation of glycolytic and cyclindependent kinase inhibitor (CDKI) gene expression ex vivo and in vivo. In addition, c-Myc inhibition upregulates major HDR modulator Rad51 expression in hematopoietic cells. Besides, c-Myc inhibition does not alter proliferation kinetics of endothelial cells, fibroblasts or adipose-derived mesenchymal stem cells, however, it limits bone marrow derived mesenchymal stem cell proliferation. We further demonstrate that a cocktail of c-Myc inhibitor 10074-G5 along with tauroursodeoxycholic acid (TUDCA) and i-NOS inhibitor L-NIL provides a robust HSC maintenance and expansion ex vivo as evident by induction of all stem cell antigens analyzed. Intriguingly, the cocktail of c-Myc inhibitor 10074-G5, TUDCA and L-NIL improves HDR related gene expression.

Conclusion:

These findings provide tools to improve ex vivo HSC maintenance and expansion, autologous HSC transplantation and gene editing through modulation of HSC glycolytic and HDR pathways.

Cancer stemness, intratumoral heterogeneity, and immune response across cancers

Regulatory programs that control the function of stem cells are active in cancer and confer properties that promote progression and therapy resistance. However, the impact of a stem cell-like tumor phenotype ("stemness") on the immunological properties of cancer has not been systematically explored. Using gene-expression-based metrics, we evaluated the association of stemness with immune cell infiltration and genomic, transcriptomic, and clinical parameters across 21 solid cancers. We found pervasive negative associations between cancer stemness and anticancer immunity. This occurred despite high stemness cancers exhibiting increased mutation load, cancer-testis antigen expression, and intratumoral heterogeneity. Stemness was also strongly associated with cell-intrinsic suppression of endogenous retroviruses and type I IFN signaling, and increased expression of multiple therapeutically accessible immunosuppressive pathways. Thus, stemness is not only a fundamental process in cancer progression but may provide a mechanistic link between antigenicity, intratumoral heterogeneity, and immune suppression across cancers.

Molecular Pathology of High-Grade Prostatic Intraepithelial Neoplasia: Challenges and Opportunities

A better understanding of the early stages of prostate cancer initiation, potentially arising from precursor lesions, may fuel development of powerful approaches for prostate cancer prevention or interception. The best-known candidate for such a precursor lesion has been referred to as high-grade prostatic intraepithelial neoplasia (HGPIN). Although there is significant evidence supporting the notion that such HGPIN lesions can give rise to invasive adenocarcinomas of the prostate, there are also numerous complicating considerations and evidence that cloud the picture in many instances. Notably, recent evidence has suggested that some fraction of such lesions that are morphologically consistent with HGPIN may actually be invasive carcinomas masquerading as HGPIN-a state that we term "postinvasive intraepithelial carcinoma" (PIC). Although the prevalence of such PIC lesions is not fully understood, this and other factors can confound the potential of identifying prostate precursors that can be targeted for disease prevention, interception, or treatment. Here, we review our current understanding of the morphological and molecular pathological features of prostate cancer precursor lesions.

Gene expression profile associated with thymus regeneration in dexamethasone-treated beef cattle

Glucocorticoids (GCs) are illegally used as growth promoters in cattle, and the analytical methods officially applied most likely underestimate the precise frequency of the abuse. As a side effect, the administration of GCs causes fat infiltration, apoptosis, and atrophy of the thymus. However, gross and histological observations carried out previously showed that the thymus preserves an intrinsic ability to regenerate. The aim of this work was to study the transcriptional effects of GCs on genes likely involved in regeneration of the epithelial cell network in the cervical and thoracic thymus of beef cattle treated with dexamethasone (DEX) or prednisolone (PRD) in comparison with a control group. Moreover, the ratio of bax/bcl2 genes was examined to verify a possible antiapoptotic activity occurring at the same time. In the cervical thymus, DEX administration increased the gene expression of c-myc (P < 0.01), tcf3 (P < 0.05), tp63 (P < 0.01), and keratin 5 (krt5; P < 0.01). In the thoracic thymus of DEX-treated cattle, the gene expression of tcf3 (P < 0.01), tp63 (P < 0.01), and krt5 (P < 0.05) was increased. These results suggested that thymic regeneration is underway in the DEX-treated animals. However, the bax/bcl2 ratio was decreased in both cervical and thoracic thymus of DEX-treated cattle (P < 0.01 and P < 0.05, respectively), showing an antiapoptotic effect through the mitochondrial pathway. Conversely, PRD administration caused no change in the expression of all considered genes. These results sustain the hypothesis that regeneration occurs in the thymus parenchyma 6 d after the DEX treatment was discontinued. This hypothesis is also supported by the absence of alterations in the thymus of PRD-treated beef cattle. Indeed, previous studies showed the inability of PRD to induce macroscopic and microscopic lesions in the thymus. Therefore, in this context, it is not surprising that PRD induced no alteration of genes involved in the regeneration pathway.

Recent Advances in Antabuse (Disulfiram): The Importance of its Metal-binding Ability to its Anticancer Activity

BACKGROUND

Considerable evidence demonstrates the importance of dithiocarbamates especially disulfiram as anticancer drugs. However there are no systematic reviews outlining how their metal-binding ability is related to their anticancer activity. This review aims to summarize chemical features and metal-binding activity of disulfiram and its metabolite DEDTC, and discuss different mechanisms of action of disulfiram and their contributions to the drug's anticancer activity.

METHODS

We undertook a disulfiram-related search on bibliographic databases of peerreviewed research literature, including many historic papers and in vitro, in vivo, preclinical and clinical studies. The selected papers were carefully reviewed and summarized.

RESULTS

More than five hundreds of papers were obtained in the initial search and one hundred eighteen (118) papers were included in the review, most of which deal with chemical and biological aspects of Disulfiram and the relationship of its chemical and biological properties. Eighty one (81) papers outline biological aspects of dithiocarbamates, and fifty seven (57) papers report biological activity of Disulfiram as an inhibitor of proteasomes or inhibitor of aldehyde dehydrogenase enzymes, interaction with other anticancer drugs, or mechanism of action related to reactive oxygen species. Other papers reviewed focus on chemical aspects of dithiocarbamates.

CONCLUSION

This review confirms the importance of chemical features of compounds such as Disulfiram to their biological activities, and supports repurposing DSF as a potential anticancer agent.

Characterization of brain tumor initiating cells isolated from an animal model of CNS primitive neuroectodermal tumors

CNS Primitive Neuroectodermal tumors (CNS-PNETs) are members of the embryonal family of malignant childhood brain tumors, which remain refractory to current therapeutic treatments. Current paradigm of brain tumorigenesis implicates brain tumor-initiating cells (BTIC) in the onset of tumorigenesis and tumor maintenance. However, despite their significance, there is currently no comprehensive characterization of CNS-PNETs BTICs. Recently, we described an animal model of CNS-PNET generated by orthotopic transplantation of human Radial Glial (RG) cells - the progenitor cells for adult neural stem cells (NSC) - into NOD-SCID mice brain and proposed that BTICs may play a role in the maintenance of these tumors. Here we report the characterization of BTIC lines derived from this CNS-PNET animal model. BTIC’s orthotopic transplantation generated highly aggressive tumors also characterized as CNS-PNETs. The BTICs have the hallmarks of NSCs as they demonstrate self-renewing capacity and have the ability to differentiate into astrocytes and early migrating neurons. Moreover, the cells demonstrate aberrant accumulation of wild type tumor-suppressor protein p53, indicating its functional inactivation, highly up-regulated levels of onco-protein cMYC and the BTIC marker OCT3/4, along with metabolic switch to glycolysis - suggesting that these changes occurred in the early stages of tumorigenesis. Furthermore, based on RNA- and DNA-seq data, the BTICs did not acquire any transcriptome-changing genomic alterations indicating that the onset of tumorigenesis may be epigenetically driven. The study of these BTIC self-renewing cells in our model may enable uncovering the molecular alterations that are responsible for the onset and maintenance of the malignant PNET phenotype.

MiR-146b-5p overexpression attenuates stemness and radioresistance of glioma stem cells by targeting HuR/lincRNA-p21/β-catenin pathway

A stem-like subpopulation existed in GBM cells, called glioma stem cells (GSCs), might contribute to cancer invasion, angiogenesis, immune evasion, and therapeutic resistance, providing a rationale to eliminate GSCs population and their supporting niche for successful GBM treatment. LincRNA-p21, a novel regulator of cell proliferation, apoptosis and DNA damage response, is found to be downregulated in several types of tumor. However, little is known about the role of lincRNA-p21 in stemness and radioresistance of GSCs and its regulating mechanisms. In this study, we found that lincRNA-p21 negatively regulated the expression and activity of β-catenin in GSCs. Downregulation of lincRNA-p21 in GSCs was resulted from upregulation of Hu antigen R (HuR) expression caused by miR-146b-5p downregulation. MiR-146b-5p overexpression increased apoptosis and radiosensitivity, decreased cell viability, neurosphere formation capacity and stem cell marker expression, and induced differentiation in GSCs. Moreover, knock-down lincRNA-p21 or HuR and β-catenin overexpression could rescue the phenotypic changes resulted from miR-146b-5p overexpression in GSCs. These findings suggest that targeting the miR-146b-5p/HuR/lincRNA-p21/β-catenin signaling pathway may be valuable therapeutic strategies against glioma.

cMyc Regulates the Size of the Premigratory Neural Crest Stem Cell Pool

The neural crest is a transient embryonic population that originates within the central nervous system (CNS) and then migrates into the periphery and differentiates into multiple cell types. The mechanisms that govern neural crest stem-like characteristics and self-renewal ability are poorly understood. Here, we show that the proto-oncogene cMyc is a critical factor in the chick dorsal neural tube, where it regulates the size of the premigratory neural crest stem cell pool. Loss of cMyc dramatically decreases the number of emigrating neural crest cells due to reduced self-renewal capacity, increased cell death, and shorter duration of the emigration process. Interestingly, rather than via E-Box binding, cMyc acts in the dorsal neural tube by interacting with another transcription factor, Miz1, to promote self-renewal. The finding that cMyc operates in a non-canonical manner in the premigratory neural crest highlights the importance of examining its role at specific time points and in an in vivo context.

Isolation, characterization, and expression of proto-oncogene cMyc in large yellow croaker Larimichthys crocea

cMyc is a vital transcription factor that involves in the regulation of cell proliferation, growth, differentiation, and apoptosis. In the present study, cMyc in Larimichthys crocea (Lc-cMyc) was cloned and analyzed for investigating its function. The full-length cDNA of Lc-cMyc was 2089 bp encoding a 440-amino-acid protein (Lc-cMyc). Lc-cMyc had the characteristic helix-loop-helix-leucine-zipper (HLH-LZ) DNA-binding domain and highly conservative in evolution. The expression of Lc-cMyc was detected by quantitative real-time PCR (qRT-PCR) and in situ hybridization, respectively. In tissues, the gender differences of Lc-cMyc expression existed only in gonad and Lc-cMyc was extremely significantly expressed in ovary with the highest level in 635-dph ovary, especially in stages II (late) and III (early) oocytes. A certain degree of expression was examined in head kidney of both sexes and testis with high expression in spermatocyte. In embryos, Lc-cMyc was expressed at all embryonic stages. In early embryogenesis (from two-cell stage to mutiple-cell stage), Lc-cMyc was expressed very highly with a peak at two-cell stage. In late embryogenesis (from blastula stage to 1-day-post-hatching stage), the high expression of Lc-cMyc was detected as the following order: 1-day-post-hatching stage > pre-hatching stage > the appearance-of-optic-vesicles stage = mutiple-cell stage > beginning-of-heart-pulsation stage. The distribution of Lc-cMyc concentrated gradually in the back of embryos until in the head. In conclusion, the spatio-temporal expression patterns of Lc-cMyc indicated an essential role in oogenesis and embryogenesis and contributed to insight into the molecular mechanisms of regulating pluripotency in large yellow croaker.

Implication of connexin30 on the stemness of glioma: connexin30 reverses the malignant phenotype of glioma by modulating IGF-1R, CD133 and cMyc

Gap-junctional intercellular communication (GJIC) plays a major role in the malignant growth of glioma. Although the mechanistic aspects of GJIC have been extensively studied, the role of connexins in the regulation of the malignant behavior of glioma stem cells (GSCs) remains unclear. In our previous studies, we have shown that connexin30 can interfere with the insulin-like growth factor 1 receptor (IGF-1R), which is known for self-renewal and pluripotency. Following our earlier in vitro observation, in this work, we aimed to study the consequence of this influence of Cx30 on IGF-1R by evaluating the marker of GSCs, CD133 and oncoprotein, cMyc. We strengthened our basis by examining human glioma samples of different grades as well as rat C6 xenografts (Cx30-transfected and -non-transfected C6 cells) along with the sphere formation assays in vitro. Investigation of stemness-related CD133 and cMyc in human samples and rat xenografts exhibited a reciprocal relationship between Cx30 and IGF-1R in the low and high grades (HG) of glioma. Cx30 was completely abolished in HG; levels of IGF-1R, CD133 and cMyc expression were positively correlated with HG. Cx30 transfection could attenuate the malignant burden of glioma in rat xenografts. Cx30 transfection also altered the tumor sphere formation of C6 glioma cells in vitro, an important property of GSCs, and there was a significant reduction of CD133 and cMyc expression by Cx30 both in vitro and in vivo. These factors indicate that dysfunction of Cx30 plays a crucial role in the prevention of the stemness of glioma, and the exploitation of this feature will help in the management of glioma.

Myc mediates cancer stem-like cells and EMT changes in triple negative breast cancers cells

Women with triple negative breast cancer (TNBC) have poor prognosis compared to other breast cancer subtypes. There were several reports indicating racial disparity in breast cancer outcomes between African American (AA) and European American (EA) women. For example, the mortality rates of AA breast cancer patients were three times higher than of EA patients, even though, the incidence is lower in AA women. Our in vitro studies indicate that cancer stem-like cells (CSCs) derived from AA TNBC cell lines have significantly higher self-renewal potential (mammosphere formation) than CSCs derived from EA cell lines. TNBC tumors express high levels of Myc compared to luminal A or HER2 expressing breast cancers. We studied the effects of c-Myc overexpression on CSCs and chemotherapy in AA, and EA derived TNBC cell line(s). Overexpression of c-Myc in AA derived MDA-MB-468 (Myc/MDA-468) cells resulted in a significant increase in CSCs and with minimal changes in epithelial-to-mesenchymal transition (EMT) compared to the control group. In contrast, overexpression of c-Myc in EA derived MDA-MB-231(Myc/MDA-231) cells led to increased epithelial-to-mesenchymal transition (EMT), with a minimal increase in CSCs compared to the control group. Myc/MDA-468 cells were resistant to standard chemotherapeutic treatments such as iniparib (PARP inhibitor) plus cisplatin, / iniparib, cisplatin, paclitaxel and docetaxel. However, Myc/MDA-231 cells, which showed EMT changes responded to iniparib with cisplatin, but were resistant to other drugs, such as iniparib, cisplatin, paclitaxel and docetaxel. Collectively, our results indicate that intrinsic differences in the tumor biology may contribute to the breast cancer disparities.

Secreted Frizzled-related protein 4 (sFRP4) chemo-sensitizes cancer stem cells derived from human breast, prostate, and ovary tumor cell lines

This study investigated molecular signals essential to sustain cancer stem cells (CSCs) and assessed their activity in the presence of secreted frizzled-related protein 4 (sFRP4) alone or in combination with chemotherapeutic drugs. SFRP4 is a known Wnt antagonist, and is also pro-apoptotic and anti-angiogenic. Additionally, sFRP4 has been demonstrated to confer chemo-sensitization and improve chemotherapeutic efficacy. CSCs were isolated from breast, prostate, and ovary tumor cell lines, and characterized using tumor-specific markers such as CD44⁺/CD24⁻/CD133⁺. The post-transcription data from CSCs that have undergone combinatorial treatment with sFRP4 and chemotherapeutic drugs suggest downregulation of stemness genes and upregulation of pro-apoptotic markers. The post-translational modification of CSCs demonstrated a chemo-sensitization effect of sFRP4 when used in combination with tumor-specific drugs. SFRP4 in combination with doxorubicin/cisplatin reduced the proliferative capacity of the CSC population in vitro. Wnt/β-catenin signaling is important for proliferation and self-renewal of CSCs in association with human tumorigenesis. The silencing of this signaling pathway by the application of sFRP4 suggests potential for improved in vivo chemo-responses.

Lawsonia intracellularis exploits β-catenin/Wnt and Notch signalling pathways during infection of intestinal crypt to alter cell homeostasis and promote cell proliferation

Lawsonia intracellularis is an obligate intracellular bacterial pathogen that causes proliferative enteropathy (PE) in pigs. L. intracellularis infection causes extensive intestinal crypt cell proliferation and inhibits secretory and absorptive cell differentiation. However, the affected host upstream cellular pathways leading to PE are still unknown. β-catenin/Wnt signalling is essential in maintaining intestinal stem cell (ISC) proliferation and self-renewal capacity, while Notch signalling governs differentiation of secretory and absorptive lineage specification. Therefore, in this report we used immunofluorescence (IF) and quantitative reverse transcriptase PCR (RTqPCR) to examine β-catenin/Wnt and Notch-1 signalling levels in uninfected and L. intracellularis infected pig ileums at 3, 7, 14, 21 and 28 days post challenge (dpc). We found that while the significant increase in Ki67+ nuclei in crypts at the peak of L. intracellularis infection suggested enhanced cell proliferation, the expression of c-MYC and ASCL2, promoters of cell growth and ISC proliferation respectively, was down-regulated. Peak infection also coincided with enhanced cytosolic and membrane-associated β-catenin staining and induction of AXIN2 and SOX9 transcripts, both encoding negative regulators of β-catenin/Wnt signalling and suggesting a potential alteration to β-catenin/Wnt signalling levels, with differential regulation of the expression of its target genes. We found that induction of HES1 and OLFM4 and the down-regulation of ATOH1 transcript levels was consistent with the increased Notch-1 signalling in crypts at the peak of infection. Interestingly, the significant down-regulation of ATOH1 transcript levels coincided with the depletion of MUC2 expression at 14 dpc, consistent with the role of ATOH1 in promoting goblet cell maturation. The lack of significant change to LGR5 transcript levels at the peak of infection suggested that the crypt hyperplasia was not due to the expansion of ISC population. Overall, simultaneous induction of Notch-1 signalling and the attenuation of β-catenin/Wnt pathway appear to be associated with the inhibition of goblet cell maturation and enhanced crypt cell proliferation at the peak of L. intracellularis infection. Moreover, the apparent differential regulation of apoptosis between crypt and lumen cells together with the strong induction of Notch-1 signalling and the enhanced SOX9 expression along crypts 14 dpc suggest an expansion of actively dividing transit amplifying and/or absorptive progenitor cells and provide a potential basis for understanding the development and maintenance of PE.

Potential Role of CD133 Expression in the Susceptibility of Human Liver Cancer Stem-Like Cells to TRAIL

Hepatocellular carcinoma (HCC) is one of the most common malignancies, with a poor prognosis and high recurrence rate. In the present study, we identified CD133, one of the markers of cancer stem cells, as a novel molecular target of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). In four human HCC cell lines established from primary HCC tumors, we found that CD133-high human liver cancer stem-like cells (CD133hi) derived from the SNU-475 cell line were highly susceptible to TRAIL compared to other HCC cell lines with a small population of CD133. CD133hi SNU-475 cells showed upregulation of TRAIL receptor DR5 and stemness-related genes such as c-Myc and ABC transporters compared to their CD133-low (CD133lo) cells. Hypersensitivity of CD133hi cells to TRAIL was associated with c-Myc-mediated upregulation of DR5 and downregulation of c-FLIPL in the cells. Knockdown of CD133 expression in CD133hi cells resulted in the downregulation of c-Myc, and depletion of c-Myc caused a decrease in the cell surface expression of DR5 and an increase in the expression of c-FLIPL and, consequently, attenuated TRAIL-induced cytotoxicity and apoptosis of CD133hi cells. These results suggest that TRAIL may provide a new strategy for CD133hi CSCs of HCC-targeted therapies and, potentially, for therapies of other CD133-expressing types of cancer.

Radiofrequency ablation-increased CXCL10 is associated with earlier recurrence of hepatocellular carcinoma by promoting stemness

Radiofrequency ablation (RFA) represents a valuable choice in hepatocellular carcinoma (HCC); however, local recurrence of HCC is common after RFA. Here, 20 primary HCC patients treated by RFA were enrolled. Before (termed 0d) and after RFA treatment for 1 and 7 days (termed 1d and 7d, respectively), plasma and noncancerous tissue were collected. ELISA assay showed that plasma C-X-C motif chemokine 10 (CXCL10) was increased in ten patients (type I patients) but decreased in the other 10 patients (type II patients). The mean interval for HCC recurrence in type I patients was less than the mean interval in type II patients. Interestingly, a significant negative correlation between interval for HCC recurrence and fold change of plasma CXCL10 (1d/0d or 7d/0d) was identified, suggesting that RFA-induced CXCL10 is associated with earlier HCC recurrence. Immunofluorescence assay showed that the receptor of CXCL10, chemokine (C-X-C motif) receptor 3 (CXCR3), was significantly increased in type I, but not type II, patients after RFA. In vitro assay demonstrated that CXCL10 stimulus increased the rate of CD133(+) cancer stem cells (CSCs) in HepG2 cells by binding to CXCR3 and then inducing c-Myc expression. Many studies have reported that induction of CD133(+) CSCs contributes to HCC recurrence. Thus, CXCL10-increased CD133(+) CSCs by activating CXCR3/c-Myc pathway might accelerate HCC recurrence after RFA. These data might have potential implications for HCC therapy.

Myc regulates programmed cell death and radial glia dedifferentiation after neural injury in an echinoderm

Background

Adult echinoderms can completely regenerate major parts of their central nervous system even after severe injuries. Even though this capacity has long been known, the molecular mechanisms that drive fast and complete regeneration in these animals have remained uninvestigated. The major obstacle for understanding these molecular pathways has been the lack of functional genomic studies on regenerating adult echinoderms.

Results

Here, we employ RNA interference-mediated gene knockdown to characterize the role of Myc during the early (first 48 hours) post-injury response in the radial nerve cord of the sea cucumber Holothuria glaberrima. Our previous experiments identified Myc as the only pluripotency-associated factor, whose expression significantly increased in the wounded CNS. The specific function(s) of this gene, however, remained unknown. Here we demonstrate that knockdown of Myc inhibits dedifferentiation of radial glia and programmed cell death, the two most prominent cellular events that take place in the regenerating sea cucumber nervous system shortly after injury.

Conclusions

In this study, we show that Myc overexpression is required for proper dedifferentiation of radial glial cells and for triggering the programmed cell death in the vicinity of the injury. Myc is thus the first transcription factor, whose functional role has been experimentally established in echinoderm regeneration.

Electronic supplementary material

The online version of this article (doi:10.1186/s12861-015-0071-z) contains supplementary material, which is available to authorized users.

Mechanisms determining the fate of hematopoietic stem cells

Successful in vitro expansion of hematopoietic stem cells (HSCs) will facilitate the application of HSC transplantation for the treatment of various diseases, including hematological malignancies. To achieve this expansion, the molecular mechanisms that control the fate of HSCs must be deciphered. Leukemia-initiating cells (LICs) or leukemia stem cells (LSCs) may originate from normal HSCs, which suggest that the dysregulation of the mechanisms that regulate the cell fate of HSCs may underlie leukemogenesis. Here we review the recent progress in the application of HSCs, the regulatory mechanisms of the fate of HSCs, and the origins of leukemia.

Cloning and characterization of rabbit POU5F1, SOX2, KLF4, C-MYC and NANOG pluripotency-associated genes

While the rabbit (Oryctolagus cuniculus) is an important research model for aspects of human development and disease that cannot be studied in rodents, the lack of data on the genetic regulation of rabbit preimplantation development is a limitation. To assist in the understanding of this process, our aim was to isolate and characterize genes necessary for the induction and maintenance of cellular pluripotency. We are the first to report the isolation of complete coding regions of rabbit SOX2, KLF4, C-MYC and NANOG, which encode transcription factors that play crucial regulatory roles during early mammalian embryonic development. We determined the exon-intron boundaries and chromosomal localization of these genes using computational analysis. The sequences of mRNA and translated protein of the newly identified genes and those of POU5F1 were aligned to their mammalian orthologs to determine the degree of evolutionary conservation. Furthermore, the expression of these genes in embryonic and adult cells was studied at the mRNA and protein levels. We found the sequences and the expression pattern of these pluripotency-associated genes to be highly conserved between human and rabbit, indicating that the rabbit would be a valuable model for human preimplantation development. Implementing the newly identified genes either as biomarkers or as reprogramming factors might also pave the way towards the creation of stable pluripotent rabbit cell lines.

Latexin inhibits the proliferation of CD133+ miapaca-2 pancreatic cancer stem-like cells

Background

An increasing number of evidence suggests that pancreatic cancer contains cancer stem cells (CSCs), which may be relevant to the resistance of chemotherapy. Latexin (Lxn) is a negative regulator of stem cell proliferation and we investigate the effects of Lxn on CD133+ pancreatic cancer stem-like cells.

Methods

CD133+ miapaca-2 cells, a human pancreatic carcinoma cell line, were isolated and sorted by magnetic activated cell sorting and flow cytometry. The capacity for self-renewal, proliferation, and tumorigenicity of CD133+ miapaca-2 cells was determined by the floating spheres test and tumor xenograft assays. Protein and mRNA expression of Lxn in CD133+ and CD133- miapaca-2 cells were detected by Western blotting and qRT-PCR, respectively. After CD133+ miapaca-2 cells were treated with Lxn in serum-free medium (SFM), cell proliferation was assayed with a Cell Counting Kit 8 (CCK-8) and apoptosis was analyzed by flow cytometry. The protein and mRNA expression levels of Bcl-2, bax, and c-myc were also analyzed.

Results

We successfully isolated CD133+ miapaca-2 cells that exhibited the capacity for self-renewal in SFM, a proliferation potential in DMEM supplemented with FBS, and high tumorigenicity in nude mice. Lxn protein and mRNA expression levels in CD133+ miapaca-2 cells were significantly lower than those in CD133- cells. Lxn-treated CD133+ miapaca-2 cells exhibited increased apoptosis and low proliferation activity, down-regulation of Bcl-2 and c-myc expression, and up-regulation of Bax expression in a dose-dependent manner.

Conclusions

Lxn induces apoptosis and inhibits the proliferation of CD133+ miapaca-2 cells. These changes are associated with down-regulation of Bcl-2 and c-myc and up-regulation of Bax.

Transcriptome-wide profiling and posttranscriptional analysis of hematopoietic stem/progenitor cell differentiation toward myeloid commitment

Hematopoietic stem cells possess lifelong self-renewal activity and generate multipotent progenitors that differentiate into lineage-committed and subsequently mature cells. We present a comparative transcriptome analysis of ex vivo isolated mouse multipotent hematopoietic stem/progenitor cells (Lin(neg)SCA-1(+)c-KIT(+)) and myeloid committed precursors (Lin(neg)SCA-1(neg)c-KIT(+)). Our data display dynamic transcriptional networks and identify a stem/progenitor gene expression pattern that is characterized by cell adhesion and immune response components including kallikrein-related proteases. We identify 498 expressed lncRNAs, which are potential regulators of multipotency or lineage commitment. By integrating these transcriptome with our recently reported proteome data, we found evidence for posttranscriptional regulation of processes including metabolism and response to oxidative stress. Finally, our study identifies a high number of genes with transcript isoform regulation upon lineage commitment. This in-depth molecular analysis outlines the enormous complexity of expressed coding and noncoding RNAs and posttranscriptional regulation during the early differentiation steps of hematopoietic stem cells toward the myeloid lineage.

Knockdown of miR-210 decreases hypoxic glioma stem cells stemness and radioresistance

Glioma contains abundant hypoxic regions which provide niches to promote the maintenance and expansion of glioma stem cells (GSCs), which are resistant to conventional therapies and responsible for recurrence. Given the fact that miR-210 plays a vital role in cellular adaption to hypoxia and in stem cell survival and stemness maintenance, strategies correcting the aberrantly expressed miR-210 might open up a new therapeutic avenue to hypoxia GSCs. In the present study, to explore the possibility of miR-210 as an effective therapeutic target to hypoxic GSCs, we employed a lentiviral-mediated anti-sense miR-210 gene transfer technique to knockdown miR-210 expression and analyze phenotypic changes in hypoxic U87s and SHG44s cells. We found that hypoxia led to an increased HIF-2α mRNA expression and miR-210 expression in GSCs. Knockdown of miR-210 decreased neurosphere formation capacity, stem cell marker expression and cell viability, and induced differentiation and G0/G1 arrest in hypoxic GSCs by partially rescued Myc antagonist (MNT) protein expression. Knockdown of MNT could reverse the gene expression changes and the growth inhibition resulting from knockdown of miR-210 in hypoxic GSCs. Moreover, knockdown of miR-210 led to increased apoptotic rate and Caspase-3/7 activity and decreased invasive capacity, reactive oxygen species (ROS) and lactate production and radioresistance in hypoxic GSCs. These findings suggest that miR-210 might be a potential therapeutic target to eliminate GSCs located in hypoxic niches.

Stem cell and extracellular matrix-related molecules increase following melatonin treatment in the skin of postmenopausal rats

The menopause has a negative effect in the skin. Melatonin affects skin functions and structures through actions mediated by cell-surface and putative-nuclear receptors expressed in skin cell. We have therefore determined the effects of melatonin treatment on stem cell in the epidermis and extracellular matrix related molecules in the dermis the skin of postmenopausal rats. A total of 45 female rats were divided into 5 groups: control group, group A [ovariectomy (OVX)], group B (OVX +10 mg/kg/day melatonin), group C (OVX +30 mg/kg/day melatonin), group S (sham operated + 10 mg/kg/day melatonin). Ventral skin samples were excised at 12th week after ovariectomy. Hematoxylin-eosin, periodic acid- methylamine silver, elastic van Gieson staining techniques were used to measure histomorphometrically the thickness of elastic fibers and basement membrane, depths of the epidermis, dermis, and subcutaneous fat layer. Immunohistochemical staining methods were used for fibroblast growth factor β (FGF β), collagen type I, fibronectin, β-catenin, c-kit, c-Myc evaluation. Epidermal thickness, subcutaneous fat layer, and elastic fibers were significantly decreased in group C, and there was a significant increase after melatonin treatment. Although there was no difference in dermal thickness of group C, melatonin also significantly increased the dermal thickness. High FGF β, type I collagen, fibronectin, β-catenin, c-Myc immunoreactivity developed following melatonin in all groups. Thus melatonin treatment of postmenopausal rats was mostly due to the decrease of stem cell and extracellular matrix-related molecules in the skin.

Posttranscriptional regulation of c-Myc expression in adult murine HSCs during homeostasis and interferon-α-induced stress response

Previous studies have established pivotal roles for c-Myc and its homolog N-Myc in hematopoietic stem cell (HSC) maintenance and niche-dependent differentiation. However, it remains largely unclear how c-Myc expression is regulated in this context. Here, we show that HSCs and more committed progenitors express similar levels of c-myc transcripts. Using knock-in mice expressing a functional enhanced green fluorescent protein-c-Myc fusion protein under control of the endogenous c-myc locus, c-Myc protein levels were assessed. Although HSCs express low levels of c-Myc protein, its expression increases steadily during progenitor differentiation. Thus, mRNA and protein expression patterns differ significantly in stem/progenitor cells, suggesting that c-Myc expression is largely controlled posttranscriptionally. Moreover, interferon-α exposure, which activates dormant HSCs, strongly induces c-Myc expression at the protein level but not at the transcript level. This posttranscriptional mechanism of c-Myc regulation provides the blood system with a rapid way to adjust c-Myc expression according to demand during hematopoietic stress.

More than just a GPCR ligand: structure-based discovery of thioridazine derivatives as Pim-1 kinase inhibitors

A structure-based hierarchical virtual screening method was employed to identify a GPCR ligand, thioridazine, as a Pim-1 kinase inhibitor.

The novel myxofibrosarcoma cell line MUG-Myx1 expresses a tumourigenic stem-like cell population with high aldehyde dehydrogenase 1 activity

BACKGROUND

Myxofibrosarcoma comprises a spectrum of malignant neoplasms withprominent myxoid stromata, cellular pleomorphism, and distinct curvilinear vascular patterns. These neoplasms mainly affect patients in the sixth to eighth decades of life and the overall 5-year survival rate is 60-70%.

METHODS

After the establishment of the novel myxofibrosarcoma cell lines MUG-Myx1, cells were characterized using short tandem repeat (STR), copy number variation (CNV), and genotype/loss-of-heterozygosity (LOH) analyses. The growth behaviour of the cells was analyzed with the xCELLigence system and an MTS assay. The tumourigenicity of MUG-Myx1 was proved in NOD/SCID mice. Additionally, a stem-like cell population with high enzymatic activity of aldehyde dehydrogenase 1 (ALDH1(high)) was isolated for the first time from myxofibrosarcoma cells using the Aldefluor® assay followed by FACS analysis.

RESULTS

The frozen primary parental tumour tissue and the MUG-Myx1 cell line showed the same STR profile at the markers D3S1358, TH01, D21S11, D18S51, Penta E, D5S818, D13S317, D7S820, D16S539, CSF1PO, Penta D, Amelogenin, D8S1179, TPOX, and FGY. Typically, myxofibrosarcoma gain and/or amplification was mapped to 7p21.3-q31.1, q31.1-q31.33, q33-q36.2, p21.3, p21.2, p14.1-q11.23, q31.33-q33, p21.2-p14.1, q11.23-q21.3, q36.2-q36.3, which, respectively are known to harbour tumour-associated genes, including TIF, BRAF, MLL3, SMO, and MET. Typically an LOH for myxofibrosarcoma on chr5 q21 was found. In addition, MUG-Myx1 ALDH1(high) cells showed an upregulation of the ABC transporter ABCB1 and ABCG2; higher c-Myc, E-cadherin and SOX-2 expression; and a higher potential for tumourigenicity and proliferation levels.

CONCLUSION

The new myxofibrosarcoma cell line MUG-Myx1 was established to enrich the bank of publicly available cell lines, with respect to providing comprehensive genetic and epigenetic characterization. Furthermore, because of their tumourigenicity, the cell line is also suitable for in vivo experiments.

Quantitative control of intracellular signaling activity through chimeric receptors incorporating multiple identical tyrosine motifs

Controlling activation levels and durations of native signaling molecules is important for efficiently controlling cellular fates. Previously we developed single-chain Fv (scFv)/cytokine receptor chimeras incorporating tyrosine motifs in the intracellular domain, which artificially control the activation of specific intracellular signaling proteins. In this study, to quantitatively control the activation levels of signaling molecules with an extended dynamic range, we constructed scFv/receptor chimeras incorporating multiple identical motifs at the different positions in the intracellular domain. We used retroviral transduction to express chimeric receptors with multiple STAT3 binding motifs connected with or without flexible linkers in a murine IL-3-dependent pro-B cell line, Ba/F3. Our results showed that the chimeric receptors can control the activation levels of STAT3 depending on ligand concentration and the number of motifs. The existence of linkers between the motifs also affected the signal intensity. Furthermore, the STAT3 activation levels significantly depended on the number of motifs rather than the distance from the JAK-binding region to the tyrosine motif.

The ubiquitin ligase FBXW7 modulates leukemia-initiating cell activity by regulating MYC stability

Sequencing efforts led to the identification of somatic mutations that could affect the self-renewal and differentiation of cancer-initiating cells. One such recurrent mutation targets the binding pocket of the ubiquitin ligase Fbxw7. Missense FBXW7 mutations are prevalent in various tumors, including T cell acute lymphoblastic leukemia (T-ALL). To study the effects of such lesions, we generated animals carrying regulatable Fbxw7 mutant alleles. Here, we show that these mutations specifically bolster cancer-initiating cell activity in collaboration with Notch1 oncogenes but spare normal hematopoietic stem cell function. We were also able to show that FBXW7 mutations specifically affect the ubiquitylation and half-life of c-Myc protein, a key T-ALL oncogene. Using animals carrying c-Myc fusion alleles, we connected Fbxw7 function to c-Myc abundance and correlated c-Myc expression to leukemia-initiating activity. Finally, we demonstrated that small-molecule-mediated suppression of MYC activity leads to T-ALL remission, suggesting an effective therapeutic strategy.

Molecular Characteristics in MRI-Classified Group 1 Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is a clinically and pathologically heterogeneous brain tumor. Previous studies of transcriptional profiling have revealed biologically relevant GBM subtypes associated with specific mutations and dysregulated pathways. Here, we applied a modified proteome to uncover abnormal protein expression profile in a MRI-classified group I GBM (GBM1), which has a spatial relationship with one of the adult neural stem cell niches, subventricular zone (SVZ). Most importantly, we identified molecular characteristics in this type of GBM that include up-regulation of metabolic enzymes, ribosomal proteins, and heat shock proteins. As GBM1 often recurs at great distances from the initial lesion, the rewiring of metabolism, and ribosomal biogenesis may facilitate cancer cells’ growth and survival during tumor progression. The intimate contact between GBM1 and the SVZ raises the possibility that tumor cells in GBM1 may be most related to SVZ cells. In support of this notion, we found that markers representing SVZ cells are highly expressed in GBM1. Emerged findings from our study provide a specific protein expression profile in GBM1 and offer better prediction or therapeutic implication for this multifocal GBM.

Multimodal actions of neural stem cells in a mouse model of ALS: a meta-analysis

Amyotrophic lateral sclerosis (ALS) is a lethal disease characterized by the unremitting degeneration of motor neurons. Multiple processes involving motor neurons and other cell types have been implicated in its pathogenesis. Neural stem cells (NSCs) perform multiple actions within the nervous system to fulfill their functions of organogenesis and homeostasis. We test the hypothesis that transplanted, undifferentiated multipotent migratory NSCs may help to ameliorate an array of pathological mechanisms in the SOD1(G93A) transgenic mouse model of ALS. On the basis of a meta-analysis of 11 independent studies performed by a consortium of ALS investigators, we propose that transplanted NSCs (both mouse and human) can slow both the onset and the progression of clinical signs and prolong survival in ALS mice, particularly if regions sustaining vital functions such as respiration are rendered chimeric. The beneficial effects of transplanted NSCs seem to be mediated by a number of actions including their ability to produce trophic factors, preserve neuromuscular function, and reduce astrogliosis and inflammation. We conclude that the widespread, pleiotropic, modulatory actions exerted by transplanted NSCs may represent an accessible therapeutic application of stem cells for treating ALS and other untreatable degenerative diseases.