Topic
Cell growth
About: Cell growth is a research topic. Over the lifetime, 104237 publications have been published within this topic receiving 3751303 citations. The topic is also known as: GO:0016049 & cellular growth.
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TL;DR: H19’s main physiological role is in limiting growth of the placenta before birth, by regulated processing of miR-675, which may also allow rapid inhibition of cell proliferation in response to cellular stress or oncogenic signals.
Abstract: The H19 large intergenic non-coding RNA (lincRNA) is one of the most highly abundant and conserved transcripts in mammalian development, being expressed in both embryonic and extra-embryonic cell lineages, yet its physiological function is unknown. Here we show that miR-675, a microRNA (miRNA) embedded in H19's first exon, is expressed exclusively in the placenta from the gestational time point when placental growth normally ceases, and placentas that lack H19 continue to grow. Overexpression of miR-675 in a range of embryonic and extra-embryonic cell lines results in their reduced proliferation; targets of the miRNA are upregulated in the H19 null placenta, including the growth-promoting insulin-like growth factor 1 receptor (Igf1r) gene. Moreover, the excision of miR-675 from H19 is dynamically regulated by the stress-response RNA-binding protein HuR. These results suggest that H19's main physiological role is in limiting growth of the placenta before birth, by regulated processing of miR-675. The controlled release of miR-675 from H19 may also allow rapid inhibition of cell proliferation in response to cellular stress or oncogenic signals.
711 citations
TL;DR: It is concluded that a form of IGF binding protein that is present in extracellular fluids and is secreted by many types of cells can markedly potentiate the cellular response to IGF-I.
Abstract: The insulin-like growth factors IGF-I and IGF-II circulate in blood bound to carrier proteins. The higher molecular mass IGF-binding protein complex (150 kDa) is composed of subunits, and one subunit that forms this complex is growth hormone dependent. In addition, many cell types and tissues secrete another form of IGF binding protein that is not growth hormone dependent. Both forms of the IGF binding protein are believed to inactivate the IGFs and to function as delivery systems to tissues. This conclusion was based on studies that determined the effects of impure preparations of these binding proteins or that examined the effect of these proteins only on the insulin-like actions of the IGFs. We report here that a pure preparation of the extracellular form of the IGF binding protein (purified from human amniotic fluid) markedly potentiated replication of several cell types in response to human IGF-I. Secondary cultures of human, mouse, and chicken embryo fibroblasts as well as porcine aortic smooth muscle cells showed marked enhancement of their DNA synthesis response (2.8- to 4.4-fold increases) to IGF-I in the presence of this protein. These responses were synergistic since the sum of the responses to either IGF-I or to the binding protein alone was between 8 and 17% of the increase obtained in cultures exposed to both peptides. The binding protein not only potentiated the DNA synthesis response but also enhanced the increase in cell number in response to IGF-I. This stimulation is specific for growth factors that bind to the binding protein since incubation with insulin, which binds to the type I IGF receptor but not to the binding protein, did not result in potentiation of this response. We conclude that a form of IGF binding protein that is present in extracellular fluids and is secreted by many types of cells can markedly potentiate the cellular response to IGF-I.
707 citations
TL;DR: It is reported that dying tumor cells use the apoptotic process to generate potent growth-stimulating signals to stimulate the repopulation of tumors undergoing radiotherapy, and activated caspase 3, a key executioner in apoptosis, is involved in the growth stimulation.
Abstract: In cancer treatment, apoptosis is a well-recognized cell death mechanism through which cytotoxic agents kill tumor cells. Here we report that dying tumor cells use the apoptotic process to generate potent growth-stimulating signals to stimulate the repopulation of tumors undergoing radiotherapy. Furthermore, activated caspase 3, a key executioner in apoptosis, is involved in the growth stimulation. One downstream effector that caspase 3 regulates is prostaglandin E(2) (PGE(2)), which can potently stimulate growth of surviving tumor cells. Deficiency of caspase 3 either in tumor cells or in tumor stroma caused substantial tumor sensitivity to radiotherapy in xenograft or mouse tumors. In human subjects with cancer, higher amounts of activated caspase 3 in tumor tissues are correlated with markedly increased rate of recurrence and death. We propose the existence of a cell death-induced tumor repopulation pathway in which caspase 3 has a major role.
707 citations
TL;DR: Current data on the structural and functional properties of CD44, the known roles for CD44 in tumorigencity, the regulation ofCD44 expression, and the potential for targeting CD44 for cancer therapy are reviewed.
Abstract: CD44, a non-kinase transmembrane glycoprotein, is overexpressed in several cell types including cancer stem cells and frequently shows alternative spliced variants that are thought to play a role in cancer development and progression. Hyaluronan, the main ligand for CD44, binds to and activates CD44 resulting in activation of cell signaling pathways that induces cell proliferation, increases cell survival, modulates cytoskeletal changes, and enhances cellular motility. The different functional roles of CD44 standard (CD44s) and specific CD44 variant (CD44v) isoforms are not fully understood. CD44v contain additional peptide motifs that can interact with and sequester growth factors and cytokines at the cell surface thereby functioning as coreceptors to facilitate cell signaling. Moreover, CD44v were expressed in metastasized tumors, whereas switching between CD44v and CD44s may play a role in regulating epithelial to mesenchymal transition (EMT) and in the adaptive plasticity of cancer cells. Here, we review current data on the structural and functional properties of CD44, the known roles for CD44 in tumorigencity, the regulation of CD44 expression, and the potential for targeting CD44 for cancer therapy.
707 citations
TL;DR: This analysis identifies JIP-1 as a specific inhibitor of the JNK signal transduction pathway and establishes protein targeting as a mechanism that regulates signaling by stress-activated MAP kinases.
Abstract: The c-Jun amino-terminal kinase (JNK) is a member of the stress-activated group of mitogen-activated protein (MAP) kinases that are implicated in the control of cell growth. A murine cytoplasmic protein that binds specifically to JNK [the JNK interacting protein-1 (JIP-1)] was characterized and cloned. JIP-1 caused cytoplasmic retention of JNK and inhibition of JNK-regulated gene expression. In addition, JIP-1 suppressed the effects of the JNK signaling pathway on cellular proliferation, including transformation by the Bcr-Abl oncogene. This analysis identifies JIP-1 as a specific inhibitor of the JNK signal transduction pathway and establishes protein targeting as a mechanism that regulates signaling by stress-activated MAP kinases.
706 citations