Showing papers on "Cell growth published in 2010"
TL;DR: Observations to date suggest that oxidative stress, chronic inflammation, and cancer are closely linked.
3,922 citations
TL;DR: The long-term growth and division patterns of Escherichia coli cells are studied by employing a microfluidic device designed to follow steady-state growth anddivision of a large number of cells at a defined reproductive age to conclude that E. coli has a robust mechanism of growth that is decoupled from cell death.
955 citations
TL;DR: In this article, a transgenic model of diphtheria-toxin-induced acute selective near-total beta-cell ablation was used to investigate whether adult mammals can differentiate (regenerate) new beta-cells after extreme, total β-cell loss, as in diabetes.
Abstract: Pancreatic insulin-producing beta-cells have a long lifespan, such that in healthy conditions they replicate little during a lifetime. Nevertheless, they show increased self-duplication after increased metabolic demand or after injury (that is, beta-cell loss). It is not known whether adult mammals can differentiate (regenerate) new beta-cells after extreme, total beta-cell loss, as in diabetes. This would indicate differentiation from precursors or another heterologous (non-beta-cell) source. Here we show beta-cell regeneration in a transgenic model of diphtheria-toxin-induced acute selective near-total beta-cell ablation. If given insulin, the mice survived and showed beta-cell mass augmentation with time. Lineage-tracing to label the glucagon-producing alpha-cells before beta-cell ablation tracked large fractions of regenerated beta-cells as deriving from alpha-cells, revealing a previously disregarded degree of pancreatic cell plasticity. Such inter-endocrine spontaneous adult cell conversion could be harnessed towards methods of producing beta-cells for diabetes therapies, either in differentiation settings in vitro or in induced regeneration.
948 citations
TL;DR: The results show for the first time that cell-produced α- Synuclein is secreted via an exosomal, calcium-dependent mechanism and suggest that α-synuclein secretion serves to amplify and propagate Parkinson's disease-related pathology.
Abstract: α-Synuclein is central in Parkinson's disease pathogenesis. Although initially α-synuclein was considered a purely intracellular protein, recent data suggest that it can be detected in the plasma and CSF of humans and in the culture media of neuronal cells. To address a role of secreted α-synuclein in neuronal homeostasis, we have generated wild-type α-synuclein and β-galactosidase inducible SH-SY5Y cells. Soluble oligomeric and monomeric species of α-synuclein are readily detected in the conditioned media (CM) of these cells at concentrations similar to those observed in human CSF. We have found that, in this model, α-synuclein is secreted by externalized vesicles in a calcium-dependent manner. Electron microscopy and liquid chromatography–mass spectrometry proteomic analysis demonstrate that these vesicles have the characteristic hallmarks of exosomes, secreted intraluminar vesicles of multivesicular bodies. Application of CM containing secreted α-synuclein causes cell death of recipient neuronal cells, which can be reversed after α-synuclein immunodepletion from the CM. High- and low-molecular-weight α-synuclein species, isolated from this CM, significantly decrease cell viability. Importantly, treatment of the CM with oligomer-interfering compounds before application rescues the recipient neuronal cells from the observed toxicity. Our results show for the first time that cell-produced α-synuclein is secreted via an exosomal, calcium-dependent mechanism and suggest that α-synuclein secretion serves to amplify and propagate Parkinson's disease-related pathology.
947 citations
TL;DR: AZD8055 is described, a novel ATP-competitive inhibitor of mTOR kinase activity, with an IC50 of 0.8 nmol/L, which results in significant growth inhibition and/or regression in xenografts, representing a broad range of human tumor types.
Abstract: The mammalian target of rapamycin (mTOR) kinase forms two multiprotein complexes, mTORC1 and mTORC2, which regulate cell growth, cell survival, and autophagy. Allosteric inhibitors of mTORC1, such as rapamycin, have been extensively used to study tumor cell growth, proliferation, and autophagy but have shown only limited clinical utility. Here, we describe AZD8055, a novel ATP-competitive inhibitor of mTOR kinase activity, with an IC50 of 0.8 nmol/L. AZD8055 showed excellent selectivity (approximately 1,000-fold) against all class I phosphatidylinositol 3-kinase (PI3K) isoforms and other members of the PI3K-like kinase family. Furthermore, there was no significant activity against a panel of 260 kinases at concentrations up to 10 micromol/L. AZD8055 inhibits the phosphorylation of mTORC1 substrates p70S6K and 4E-BP1 as well as phosphorylation of the mTORC2 substrate AKT and downstream proteins. The rapamycin-resistant T37/46 phosphorylation sites on 4E-BP1 were fully inhibited by AZD8055, resulting in significant inhibition of cap-dependent translation. In vitro, AZD8055 potently inhibits proliferation and induces autophagy in H838 and A549 cells. In vivo, AZD8055 induces a dose-dependent pharmacodynamic effect on phosphorylated S6 and phosphorylated AKT at plasma concentrations leading to tumor growth inhibition. Notably, AZD8055 results in significant growth inhibition and/or regression in xenografts, representing a broad range of human tumor types. AZD8055 is currently in phase I clinical trials.
727 citations
TL;DR: Control of cell size and cell cycle progression appear to be independent in mammalian cells, whereas in lower eukaryotes, 4E-BPs influence both cell growth and proliferation.
Abstract: The mammalian target of rapamycin complex 1 (mTORC1) integrates mitogen and nutrient signals to control cell proliferation and cell size. Hence, mTORC1 is implicated in a large number of human diseases--including diabetes, obesity, heart disease, and cancer--that are characterized by aberrant cell growth and proliferation. Although eukaryotic translation initiation factor 4E-binding proteins (4E-BPs) are critical mediators of mTORC1 function, their precise contribution to mTORC1 signaling and the mechanisms by which they mediate mTORC1 function have remained unclear. We inhibited the mTORC1 pathway in cells lacking 4E-BPs and analyzed the effects on cell size, cell proliferation, and cell cycle progression. Although the 4E-BPs had no effect on cell size, they inhibited cell proliferation by selectively inhibiting the translation of messenger RNAs that encode proliferation-promoting proteins and proteins involved in cell cycle progression. Thus, control of cell size and cell cycle progression appear to be independent in mammalian cells, whereas in lower eukaryotes, 4E-BPs influence both cell growth and proliferation.
666 citations
TL;DR: By manipulating micropattern shapes, cells were shown to precisely adapt their cytoskeleton architecture to the geometry of their microenvironment, revealing fundamental cell morphogenetic processes as highlighted in this review.
Abstract: In situ, cells are highly sensitive to geometrical and mechanical constraints from their microenvironment. These parameters are, however, uncontrolled under classic culture conditions, which are thus highly artefactual. Micro-engineering techniques provide tools to modify the chemical properties of cell culture substrates at sub-cellular scales. These can be used to restrict the location and shape of the substrate regions, in which cells can attach, so-called micropatterns. Recent progress in micropatterning techniques has enabled the control of most of the crucial parameters of the cell microenvironment. Engineered micropatterns can provide a micrometer-scale, soft, 3-dimensional, complex and dynamic microenvironment for individual cells or for multi-cellular arrangements. Although artificial, micropatterned substrates allow the reconstitution of physiological in situ conditions for controlled in vitro cell culture and have been used to reveal fundamental cell morphogenetic processes as highlighted in this review. By manipulating micropattern shapes, cells were shown to precisely adapt their cytoskeleton architecture to the geometry of their microenvironment. Remodelling of actin and microtubule networks participates in the adaptation of the entire cell polarity with respect to external constraints. These modifications further impact cell migration, growth and differentiation.
664 citations
TL;DR: The results suggest that self-renewal of mature Treg cells serves as a major mechanism of maintenance of the Treg cell lineage in adult mice.
Abstract: Tissue maintenance and homeostasis can be achieved through the replacement of dying cells by differentiating precursors or self-renewal of terminally differentiated cells or relies heavily on cellular longevity in poorly regenerating tissues. Regulatory T cells (T(reg) cells) represent an actively dividing cell population with critical function in suppression of lethal immune-mediated inflammation. The plasticity of T(reg) cells has been actively debated because it could factor importantly in protective immunity or autoimmunity. By using inducible labeling and tracking of T(reg) cell fate in vivo, or transfers of highly purified T(reg) cells, we have demonstrated notable stability of this cell population under physiologic and inflammatory conditions. Our results suggest that self-renewal of mature T(reg) cells serves as a major mechanism of maintenance of the T(reg) cell lineage in adult mice.
644 citations
TL;DR: It is found that STAT3 bound to multiple genes involved in Th17 cell differentiation, cell activation, proliferation, and survival, regulating both expression and epigenetic modifications, and orchestrates multiple critical aspects of T cell function in inflammation and homeostasis.
635 citations
TL;DR: It is demonstrated that NOTCH pathway blockade depletes stem‐like cells in GBMs, suggesting that GSIs may be useful as chemotherapeutic reagents to target CSCs in malignant gliomas.
Abstract: Cancer stem cells (CSCs) are thought to be critical for the engraftment and long-term growth of many tumors, including glioblastoma (GBM). The cells are at least partially spared by traditional chemotherapies and radiation therapies, and finding new treatments that can target CSCs may be critical for improving patient survival. It has been shown that the NOTCH signaling pathway regulates normal stem cells in the brain, and that GBMs contain stem-like cells with higher NOTCH activity. We therefore used low-passage and established GBM-derived neurosphere cultures to examine the overall requirement for NOTCH activity, and also examined the effects on tumor cells expressing stem cell markers. NOTCH blockade by γ-secretase inhibitors (GSIs) reduced neurosphere growth and clonogenicity in vitro, whereas expression of an active form of NOTCH2 increased tumor growth. The putative CSC markers CD133, NESTIN, BMI1, and OLIG2 were reduced following NOTCH blockade. When equal numbers of viable cells pretreated with either vehicle (dimethyl sulfoxide) or GSI were injected subcutaneously into nude mice, the former always formed tumors, whereas the latter did not. In vivo delivery of GSI by implantation of drug-impregnated polymer beads also effectively blocked tumor growth, and significantly prolonged survival, albeit in a relatively small cohort of animals. We found that NOTCH pathway inhibition appears to deplete stem-like cancer cells through reduced proliferation and increased apoptosis associated with decreased AKT and STAT3 phosphorylation. In summary, we demonstrate that NOTCH pathway blockade depletes stem-like cells in GBMs, suggesting that GSIs may be useful as chemotherapeutic reagents to target CSCs in malignant gliomas.
628 citations
TL;DR: Angiogenic models are developed to demonstrate that EC-derived angiocrine growth factors support in vitro self-renewal and in vivo repopulation of authentic LT-HSCs, and establish an instructive vascular niche for clinical-scale expansion of LT- HSCs and a cellular platform to identify stem cell-active trophogens.
TL;DR: Pax7 is a target of two miRNAs that are induced during muscle satellite cell differentiation and repressed in response to muscle injury.
Abstract: Skeletal muscle satellite cells are adult stem cells responsible for postnatal skeletal muscle growth and regeneration. Paired-box transcription factor Pax7 plays a central role in satellite cell survival, self-renewal, and proliferation. However, how Pax7 is regulated during the transition from proliferating satellite cells to differentiating myogenic progenitor cells is largely unknown. In this study, we find that miR-1 and miR-206 are sharply up-regulated during satellite cell differentiation and down-regulated after muscle injury. We show that miR-1 and miR-206 facilitate satellite cell differentiation by restricting their proliferative potential. We identify Pax7 as one of the direct regulatory targets of miR-1 and miR-206. Inhibition of miR-1 and miR-206 substantially enhances satellite cell proliferation and increases Pax7 protein level in vivo. Conversely, sustained Pax7 expression as a result of the loss of miR-1 and miR-206 repression elements at its 3′ untranslated region significantly inhibits myoblast differentiation. Therefore, our experiments suggest that microRNAs participate in a regulatory circuit that allows rapid gene program transitions from proliferation to differentiation.
TL;DR: In this paper, the role of miR-21 in non-small cell lung cancer (NSCLC) and to clarify the regulation of PTEN by miR21 and determine mechanisms of this regulation were identified.
TL;DR: It is found that Mst1 and Mst2, the two mouse homologs of the Drosophila Hpo, control the sizes of some, but not all organs, in mice, and MSt1 andMst2 act as tumor suppressors by restricting cell proliferation and survival.
Abstract: Control of organ size by cell proliferation and survival is a fundamental developmental process, and its deregulation leads to cancer. However, the molecular mechanism underlying organ size control remains elusive in vertebrates. In Drosophila, the Hippo (Hpo) signaling pathway controls organ size by both restricting cell growth and proliferation and promoting cell death. Here we investigated whether mammals also require the Hpo pathway to control organ size and adult tissue homeostasis. We found that Mst1 and Mst2, the two mouse homologs of the Drosophila Hpo, control the sizes of some, but not all organs, in mice, and Mst1 and Mst2 act as tumor suppressors by restricting cell proliferation and survival. We show that Mst1 and Mst2 play redundant roles, and removal of both resulted in early lethality in mouse embryos. Importantly, tumors developed in the liver with a substantial increase of the stem/progenitor cells by 6 months after removing Mst1 and Mst2 postnatally. We show that Mst1 and Mst2 were required in vivo to control Yap phosphorylation and activity. Interestingly, apoptosis induced by TNFα was blocked in the Mst1 and Mst2 double-mutant cells both in vivo and in vitro. As TNFα is a pleiotropic inflammatory cytokine affecting most organs by regulating cell proliferation and cell death, resistance to TNFα-induced cell death may also contribute significantly to tumor formation in the absence of Mst1 and Mst2.
TL;DR: It is demonstrated that a paracrine mechanism driven by DeltaEGFR is the primary means for recruiting wtEGFR-expressing cells into accelerated proliferation in vivo, and support the view that a minor tumor cell population can potently drive accelerated growth of the entire tumor mass, and thereby actively maintain tumor cell heterogeneity within a tumor mass.
Abstract: Human solid tumors frequently have pronounced heterogeneity of both neoplastic and normal cells on the histological, genetic, and gene expression levels. While current efforts are focused on understanding heterotypic interactions between tumor cells and surrounding normal cells, much less is known about the interactions between and among heterogeneous tumor cells within a neoplasm. In glioblastoma multiforme (GBM), epidermal growth factor receptor gene (EGFR) amplification and mutation (EGFRvIII/ΔEGFR) are signature pathogenetic events that are invariably expressed in a heterogeneous manner. Strikingly, despite its greater biological activity than wild-type EGFR (wtEGFR), individual GBM tumors expressing both amplified receptors typically express wtEGFR in far greater abundance than the ΔEGFR lesion. We hypothesized that the minor ΔEGFR-expressing subpopulation enhances tumorigenicity of the entire tumor cell population, and thereby maintains heterogeneity of expression of the two receptor forms in different cells. Using mixtures of glioma cells as well as immortalized murine astrocytes, we demonstrate that a paracrine mechanism driven by ΔEGFR is the primary means for recruiting wtEGFR-expressing cells into accelerated proliferation in vivo. We determined that human glioma tissues, glioma cell lines, glioma stem cells, and immortalized mouse Ink4a/Arf−/− astrocytes that express ΔEGFR each also express IL-6 and/or leukemia inhibitory factor (LIF) cytokines. These cytokines activate gp130, which in turn activates wtEGFR in neighboring cells, leading to enhanced rates of tumor growth. Ablating IL-6, LIF, or gp130 uncouples this cellular cross-talk, and potently attenuates tumor growth enhancement. These findings support the view that a minor tumor cell population can potently drive accelerated growth of the entire tumor mass, and thereby actively maintain tumor cell heterogeneity within a tumor mass. Such interactions between genetically dissimilar cancer cells could provide novel points of therapeutic intervention.
TL;DR: The study suggests that interventional tools able to revert the MØ infiltrate towards the M2 phenotype may exert an atheroprotective action.
Abstract: As in human disease, macrophages (MO) are central players in the development and progression of experimental atherosclerosis. In this study we have evaluated the phenotype of MO associated with progression of atherosclerosis in the apolipoprotein E (ApoE) knockout (KO) mouse model.We found that bone marrow-derived MO submitted to M1 and M2 polarization specifically expressed arginase (Arg) II and Arg I, respectively. This distinct arginase expression was used to evaluate the frequency and distribution of M1 and M2 MO in cross-sections of atherosclerotic plaques of ApoE KO mice. Early lesions were infiltrated by Arg I(+) (M2) MO. This type of MO favored the proliferation of smooth muscle cells, in vitro. Arg II(+) (M1) MO appeared and prevailed in lesions of aged ApoE KO mice and lesion progression was correlated with the dominance of M1 over the M2 MO phenotype. In order to address whether the M2->M1 switch could be due to a phenotypic switch of the infiltrated cells, we performed in vitro repolarization experiments. We found that fully polarized MO retained their plasticity since they could revert their phenotype. The analysis of the distribution of Arg I- and Arg II-expressing MO also argued against a recent recruitment of M1 MO in the lesion. The combined data therefore suggest that the M2->M1 switch observed in vivo is due to a conversion of cells already present in the lesion. Our study suggests that interventional tools able to revert the MO infiltrate towards the M2 phenotype may exert an atheroprotective action.
TL;DR: Analysis of plasma kynurenine/tryptophan levels in patients with cancer affirms that the IDO pathway is activated in multiple tumor types and suggests that selective inhibition of IDO1 may represent an attractive cancer therapeutic strategy via up-regulation of cellular immunity.
TL;DR: Differences in metabolic and cell-cycle regulation between HSCs and some other haematopoietic progenitors are revealed, revealed through AMPK-dependent and AM PK-independent mechanisms.
Abstract: Little is known about metabolic regulation in stem cells and how this modulates tissue regeneration or tumour suppression. We studied the Lkb1 tumour suppressor and its substrate AMP-activated protein kinase (AMPK), kinases that coordinate metabolism with cell growth. Deletion of the Lkb1 (also called Stk11) gene in mice caused increased haematopoietic stem cell (HSC) division, rapid HSC depletion and pancytopenia. HSCs depended more acutely on Lkb1 for cell-cycle regulation and survival than many other haematopoietic cells. HSC depletion did not depend on mTOR activation or oxidative stress. Lkb1-deficient HSCs, but not myeloid progenitors, had reduced mitochondrial membrane potential and ATP levels. HSCs deficient for two catalytic α-subunits of AMPK (AMPK-deficient HSCs) showed similar changes in mitochondrial function but remained able to reconstitute irradiated mice. Lkb1-deficient HSCs, but not AMPK-deficient HSCs, exhibited defects in centrosomes and mitotic spindles in culture, and became aneuploid. Lkb1 is therefore required for HSC maintenance through AMPK-dependent and AMPK-independent mechanisms, revealing differences in metabolic and cell-cycle regulation between HSCs and some other haematopoietic progenitors.
TL;DR: It is shown that miR396 attenuates cell proliferation in developing leaves, through the repression of GRF activity and a decrease in the expression of cell cycle genes, and can regulate cell proliferation and the size of the meristem.
Abstract: Cell proliferation is an important determinant of plant form, but little is known about how developmental programs control cell division. Here, we describe the role of microRNA miR396 in the coordination of cell proliferation in Arabidopsis leaves. In leaf primordia, miR396 is expressed at low levels that steadily increase during organ development. We found that miR396 antagonizes the expression pattern of its targets, the GROWTH-REGULATING FACTOR (GRF) transcription factors. miR396 accumulates preferentially in the distal part of young developing leaves, restricting the expression of GRF2 to the proximal part of the organ. This, in turn, coincides with the activity of the cell proliferation marker CYCLINB1;1. We show that miR396 attenuates cell proliferation in developing leaves, through the repression of GRF activity and a decrease in the expression of cell cycle genes. We observed that the balance between miR396 and the GRFs controls the final number of cells in leaves. Furthermore, overexpression of miR396 in a mutant lacking GRF-INTERACTING FACTOR 1 severely compromises the shoot meristem. We found that miR396 is expressed at low levels throughout the meristem, overlapping with the expression of its target, GRF2. In addition, we show that miR396 can regulate cell proliferation and the size of the meristem. Arabidopsis plants with an increased activity of the transcription factor TCP4, which reduces cell proliferation in leaves, have higher miR396 and lower GRF levels. These results implicate miR396 as a significant module in the regulation of cell proliferation in plants.
TL;DR: The structure and function of integrins, their roles in disease and the chequered history of the approved integrin antagonists are discussed.
Abstract: The integrins are a large family of cell adhesion molecules that are essential for the regulation of cell growth and function The identification of key roles for integrins in a diverse range of diseases, including cancer, infection, thrombosis and autoimmune disorders, has revealed their substantial potential as therapeutic targets However, so far, pharmacological inhibitors for only three integrins have received marketing approval This article discusses the structure and function of integrins, their roles in disease and the chequered history of the approved integrin antagonists Recent advances in the understanding of integrin function, ligand interaction and signalling pathways suggest novel strategies for inhibiting integrin function that could help harness their full potential as therapeutic targets
TL;DR: Overexpression of miR-451 sensitized cells to glucose deprivation, suggesting that its downregulation is necessary for robust activation of LKB1 in response to metabolic stress, and this may represent a fundamental mechanism that contributes to cellular adaptation in Response to altered energy availability.
TL;DR: It is shown that “senescent” mouse fibroblasts, which arrested growth after repeated passage under standard culture conditions, do not express a human-like SASP, and differ from similarly cultured human cells in other respects, but when cultured in physiological oxygen and induced to senesce by radiation, mouse cells more closely resemble human cells, including expression of a robust SASP.
Abstract: Cellular senescence irreversibly arrests cell proliferation in response to oncogenic stimuli. Human cells develop a senescence-associated secretory phenotype (SASP), which increases the secretion of cytokines and other factors that alter the behavior of neighboring cells. We show here that “senescent” mouse fibroblasts, which arrested growth after repeated passage under standard culture conditions (20% oxygen), do not express a human-like SASP, and differ from similarly cultured human cells in other respects. However, when cultured in physiological (3%) oxygen and induced to senesce by radiation, mouse cells more closely resemble human cells, including expression of a robust SASP. We describe two new aspects of the human and mouse SASPs. First, cells from both species upregulated the expression and secretion of several matrix metalloproteinases, which comprise a conserved genomic cluster. Second, for both species, the ability to promote the growth of premalignant epithelial cells was due primarily to the conserved SASP factor CXCL-1/KC/GRO-α. Further, mouse fibroblasts made senescent in 3%, but not 20%, oxygen promoted epithelial tumorigenesis in mouse xenographs. Our findings underscore critical mouse-human differences in oxygen sensitivity, identify conditions to use mouse cells to model human cellular senescence, and reveal novel conserved features of the SASP.
TL;DR: The results challenge the current paradigm that B cell activation plays an overall protective role in atherogenesis and identify new antiatherogenic strategies based on B cell modulation.
Abstract: B cell depletion significantly reduces the burden of several immune-mediated diseases. However, B cell activation has been until now associated with a protection against atherosclerosis, suggesting that B cell-depleting therapies would enhance cardiovascular risk. We unexpectedly show that mature B cell depletion using a CD20-specific monoclonal antibody induces a significant reduction of atherosclerosis in various mouse models of the disease. This treatment preserves the production of natural and potentially protective anti-oxidized low-density lipoprotein (oxLDL) IgM autoantibodies over IgG type anti-oxLDL antibodies, and markedly reduces pathogenic T cell activation. B cell depletion diminished T cell-derived IFN-gamma secretion and enhanced production of IL-17; neutralization of the latter abrogated CD20 antibody-mediated atheroprotection. These results challenge the current paradigm that B cell activation plays an overall protective role in atherogenesis and identify new antiatherogenic strategies based on B cell modulation.
TL;DR: Enhanced understanding of the regulation of PG metabolism and the involvement of PGs in cancer may offer a novel approach to cancer therapy by targeting the tumor microenvironment.
Abstract: The expression of proteoglycans (PGs), essential macromolecules of the tumor microenvironment, is markedly altered during malignant transformation and tumor progression. Synthesis of stromal PGs is affected by factors secreted by cancer cells and the unique tumor-modified extracellular matrix may either facilitate or counteract the growth of solid tumors. The emerging theme is that this dual activity has intrinsic tissue specificity. Matrix-accumulated PGs, such as versican, perlecan and small leucine-rich PGs, affect cancer cell signaling, growth and survival, cell adhesion, migration and angiogenesis. Furthermore, expression of cell-surface-associated PGs, such as syndecans and glypicans, is also modulated in both tumor and stromal cells. Cell-surface-associated PGs bind various factors that are involved in cell signaling, thereby affecting cell proliferation, adhesion and motility. An important mechanism of action is offered by a proteolytic processing of cell-surface PGs known as ectodomain shedding of syndecans; this facilitates cancer and endothelial cell motility, protects matrix proteases and provides a chemotactic gradient of mitogens. However, syndecans on stromal cells may be important for stromal cell/cancer cell interplay and may promote stromal cell proliferation, migration and angiogenesis. Finally, abnormal PG expression in cancer and stromal cells may serve as a biomarker for tumor progression and patient survival. Enhanced understanding of the regulation of PG metabolism and the involvement of PGs in cancer may offer a novel approach to cancer therapy by targeting the tumor microenvironment. In this minireview, the implication of PGs in cancer development and progression, as well as their pharmacological targeting in malignancy, are presented and discussed.
TL;DR: It is demonstrated thatmiR-221 and miR-222 regulate radiosensitivity, and cell growth and invasion of SGC7901 cells, possibly via direct modulation of PTEN expression.
Abstract: MicroRNAs (miRNAs) can function as either oncogenes or tumor suppressor genes via regulation of cell proliferation and/or apoptosis. MiR-221 and miR-222 were discovered to induce cell growth and cell cycle progression via direct targeting of p27 and p57 in various human malignancies. However, the roles of miR-221 and miR-222 have not been reported in human gastric cancer. In this study, we examined the impact of miR-221 and miR-222 on human gastric cancer cells, and identified target genes for miR-221 and miR-222 that might mediate their biology. The human gastric cancer cell line SGC7901 was transfected with AS-miR-221/222 or transduced with pMSCV-miR-221/222 to knockdown or restore expression of miR-221 and miR-222, respectively. The effects of miR-221 and miR-222 were then assessed by cell viability, cell cycle analysis, apoptosis, transwell, and clonogenic assay. Potential target genes were identified by Western blot and luciferase reporter assay. Upregulation of miR-221 and miR-222 induced the malignant phenotype of SGC7901 cells, whereas knockdown of miR-221 and miR-222 reversed this phenotype via induction of PTEN expression. In addition, knockdonwn of miR-221 and miR-222 inhibited cell growth and invasion and increased the radiosensitivity of SGC7901 cells. Notably, the seed sequence of miR-221 and miR-222 matched the 3'UTR of PTEN, and introducing a PTEN cDNA without the 3'UTR into SGC7901 cells abrogated the miR-221 and miR-222-induced malignant phenotype. PTEN-3'UTR luciferase reporter assay confirmed PTEN as a direct target of miR-221 and miR-222. These results demonstrate that miR-221 and miR-222 regulate radiosensitivity, and cell growth and invasion of SGC7901 cells, possibly via direct modulation of PTEN expression. Our study suggests that inhibition of miR-221 and miR-222 might form a novel therapeutic strategy for human gastric cancer.
TL;DR: It is suggested that β‐caryophyllene facilitates the passage of paclitaxel through the membrane and thus potentiates its anticancer activity, and induces intracellular accumulation of calcein but not verapamil, an inhibitor of P‐glycoprotein and multidrug resistance related protein transporters, suggesting that β-caryphyllene promotes drug accumulation by a different mechanism of action.
Abstract: beta-caryophyllene is a sesquiterpene widely distributed in essential oils of various plants. Several biological activities are attributed to beta-caryophyllene, such as anti-inflammatory, antibiotic, antioxidant, anticarcinogenic and local anaesthetic activities. In this work, the potentiating effect of beta-caryophyllene on the anticancer activity of alpha-humulene, isocaryophyllene and paclitaxel against MCF-7, DLD-1 and L-929 human tumour cell lines was evaluated. A non-cytotoxic concentration of beta-caryophyllene significantly increased the anticancer activity of alpha-humulene and isocaryophyllene on MCF-7 cells: alpha-humulene or isocaryophyllene alone (32 microg mL(-1)) inhibited cell growth by about 50% and 69%, respectively, compared with 75% and 90% when combined with 10 microg mL(-1) beta-caryophyllene. Moreover, beta-caryophyllene potentiated the anticancer activity of paclitaxel on MCF-7, DLD-1 and L-929 cell lines. The highest potentiating effect was obtained in DLD-1 cells treated with paclitaxel combined with 10 microg mL(-1) beta-caryophyllene, which increased the paclitaxel activity about 10-fold. The intracellular accumulation of paclitaxel-oregon green was evaluated in combination with concentrations of beta-caryophyllene ranging from 2.5 to 40 microg mL(-1). beta-Caryophyllene (10 microg mL(-1)) significantly increased the intracellular accumulation of paclitaxel-oregon green (about 64% over controls). Moreover, beta-caryophyllene induced intracellular accumulation of calcein but not verapamil, an inhibitor of P-glycoprotein and multidrug resistance related protein transporters, suggesting that beta-caryophyllene promotes drug accumulation by a different mechanism of action. These results suggest that beta-caryophyllene facilitates the passage of paclitaxel through the membrane and thus potentiates its anticancer activity.
TL;DR: In this article, the authors show that miR-145 exerts its function in a cell-specific manner, which is in part due to the silencing of the metastasis gene mucin 1 (MUC1).
Abstract: MicroRNAs are important gene regulators that could play a profound role in tumorigenesis. Our previous studies indicate that miR-145 is a tumor suppressor capable of inhibiting tumor cell growth both in vitro and in vivo. In this study, we show that miR-145 exerts its function in a cell-specific manner. Although miR-145 inhibits cell growth in MCF-7 and HCT-116 cells, it has no significant effect on cell growth in metastatic breast cancer cell lines. However, miR-145 significantly suppresses cell invasion in these cells; in contrast, the antisense oligo against miR-145 increases cell invasion. miR-145 is also able to suppress lung metastasis in an experimental metastasis animal model. This miR-145–mediated suppression of cell invasion is in part due to the silencing of the metastasis gene mucin 1 (MUC1). Using luciferase reporters carrying the 3′-untranslated region of MUC1 combined with Western blot and immunofluorescence staining, we identify MUC1 as a direct target of miR-145. Moreover, ectopic expression of MUC1 enhances cell invasion, which can be blocked by miR-145. Of interest, suppression of MUC1 by miR-145 causes a reduction of β-catenin as well as the oncogenic cadherin 11. Finally, suppression of MUC1 by RNAi mimics the miR-145 action in suppression of invasion, which is associated with downregulation of β-catenin and cadherin 11. Taken together, these results suggest that as a tumor suppressor, miR-145 inhibits not only tumor growth but also cell invasion and metastasis. Cancer Res; 70(1); 378–87
Journal Article•
TL;DR: In this article, the role of microRNA miR396 in the coordination of cell proliferation in Arabidopsis leaves was investigated and shown to be a significant module in the regulation of plant proliferation in plants.
Abstract: Cell proliferation is an important determinant of plant form, but little is known about how developmental programs control cell division. Here, we describe the role of microRNA miR396 in the coordination of cell proliferation in Arabidopsis leaves. In leaf primordia, miR396 is expressed at low levels that steadily increase during organ development. We found that miR396 antagonizes the expression pattern of its targets, the GROWTH-REGULATING FACTOR (GRF) transcription factors. miR396 accumulates preferentially in the distal part of young developing leaves, restricting the expression of GRF2 to the proximal part of the organ. This, in turn, coincides with the activity of the cell proliferation marker CYCLINB1;1. We show that miR396 attenuates cell proliferation in developing leaves, through the repression of GRF activity and a decrease in the expression of cell cycle genes. We observed that the balance between miR396 and the GRFs controls the final number of cells in leaves. Furthermore, overexpression of miR396 in a mutant lacking GRF-INTERACTING FACTOR 1 severely compromises the shoot meristem. We found that miR396 is expressed at low levels throughout the meristem, overlapping with the expression of its target, GRF2. In addition, we show that miR396 can regulate cell proliferation and the size of the meristem. Arabidopsis plants with an increased activity of the transcription factor TCP4, which reduces cell proliferation in leaves, have higher miR396 and lower GRF levels. These results implicate miR396 as a significant module in the regulation of cell proliferation in plants.
TL;DR: In this article, the authors investigated how these cell polarity regulators control proliferation and survival in Drosophila neoplastic tumor suppressor pathway. And they showed that Lgl depletion or aPKC overexpression results in comislocalization of Hippo and Ras-associated domain family protein (RASSF), consistent with RASSF's ability to block Hippo activation by Salvador.
TL;DR: In this paper, the identification and characterization of tumor-initiating cells (TICs) from hepatocellular carcinoma (HCC) using the marker CD133 was described.