Transforming growth factor β1 selectively regulates ferritin gene expression in malignant H-ras-transformed fibrosarcoma cell lines

2000 ◽  
Vol 78 (4) ◽  
pp. 527-535 ◽  
Author(s):  
James Lo ◽  
Robert AR Hurta
Keyword(s):  
Gene Expression ◽  
Cell Proliferation ◽  
Growth Factor ◽  
Malignant Transformation ◽  
Cell Lines ◽  
Transforming Growth Factor ◽  
Malignant Potential ◽  
Transformed Cells ◽  
Protein Synthesis Inhibitor ◽  
Ferritin Gene

Transforming growth factor β1 is an important growth regulator in many cell types, usually exerting a negative effect on cellular growth. Inhibition of DNA synthesis and cell proliferation is frequently lost during malignant transformation, and in some cases, tumor cell proliferation is actually stimulated by TGF-β1. The present study demonstrates a novel link between alterations in TGF-β1 regulation during malignant conversion, and the expression of ferritin, an important activity involved in a number of biological functions including iron homeostasis and cell-growth control. A series of H-ras-transformed mouse 10 T 1/2 cell lines, exhibiting increasing malignant potential, was investigated for possible TGF-β1-mediated changes in ferritin gene expression. Selective induction of gene expression was observed, since only H-ras-transformed cells with malignant potential exhibited marked elevations in ferritin gene expression, in particular, alterations in H-ferritin gene expression. The regulation of H-ferritin gene expression in response to TGF-β 1 did not involve alterations in transcription, but occurred through mechanisms of post-transcriptional stabilization of the H-ferritin mRNA. Additionally, evidence was obtained for a cycloheximide-sensitive regulator of H-ferritin gene expression, since the presence of this protein synthesis inhibitor increased H-ferritin message levels, and in combination with TGF-β1, cooperated in an additive manner to augment H-ferritin gene expression. These results show for the first time that TGF-β1 can regulate ferritin gene expression in malignant H-ras transformed cells, and suggest a mechanism for growth factor stimulation of malignant cells, in which early alterations in the control of H-ferritin gene expression are important.Key words: TGF-β1, ferritin gene expression, malignant transformation.

scholarly journals Dual Role for Transforming Growth Factor β-Dependent Signaling in Trypanosoma cruzi Infection of Mammalian Cells

2000 ◽  
Vol 68 (4) ◽  
pp. 2077-2081 ◽  
Author(s):  
Belinda S. Hall ◽  
Miercio A. Pereira
Keyword(s):  
Gene Expression ◽  
Growth Factor ◽  
Trypanosoma Cruzi ◽  
Host Cell ◽  
Cell Lines ◽  
Mammalian Cells ◽  
Transforming Growth Factor ◽  
Growth Arrest ◽  
Transforming Growth Factor Β

ABSTRACT Expression of functional transforming growth factor β (TGF-β) receptors (TβR) is required for the invasion of mammalian cells by the protozoan parasite Trypanosoma cruzi. However, the precise role of this host cell signaling complex in T. cruzi infection is unknown. To investigate the role of the TGF-β signaling pathway, infection levels were studied in the mink lung epithelial cell lines JD1, JM2, and JM3. These cells express inducible mutant TβR1 proteins that cannot induce growth arrest in response to TGF-β but still transmit the signal for TGF-β-dependent gene expression. In the absence of mutant receptor expression, trypomastigotes invaded the cells at a low level. Induction of the mutant receptors caused an increase in infection in all three cell lines, showing that the requirement for TGF-β signaling at invasion can be divorced from TGF-β-induced growth arrest. TGF-β pretreatment of mink lung cells expressing wild-type TβR1 caused a marked enhancement of infection, but no enhancement was seen in JD1, JM2, and JM3 cells, showing that the ability of TGF-β to stimulate infection is associated with growth arrest. Likewise, expression of SMAD7 or SMAD2SA, inhibitors of TGF-β signaling, did not block infection by T. cruzi but did block the enhancement of infection by TGF-β. Taken together, these results show that there is a dual role for TGF-β signaling in T. cruzi infection. The initial invasion of the host cell is independent of both TGF-β-dependent gene expression and growth arrest, but TGF-β stimulation of infection requires a fully functional TGF-β signaling pathway.

Constitutive and Stimulated Production of Vegf by Human Megakaryoblastic Cell Lines: Effect on Proliferation and Signaling Pathway

2005 ◽  
Vol 18 (3) ◽  
pp. 445-455 ◽  
Author(s):  
L. Bonsi ◽  
L. Pierdomenico ◽  
M. Biscardi ◽  
C. Marchionni ◽  
S. Gavazzi ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Growth Factor ◽  
Cell Lines ◽  
Transforming Growth Factor ◽  
Transforming Growth Factor Β ◽  
Neoplastic Cell ◽  
Elisa Test ◽  
Leukemic Cells ◽  
Vegf Expression ◽  
Hel Cells

Release of vascular endothelial growth factor (VEGF) and other candidate angiogenic factors such as basic fibroblast growth factor and transforming growth factor β, may play a role in sustaining neoplastic cell proliferation and tumor growth. We evaluated VEGF expression and synthesis in the two erythro-megakaryocytic cell lines B1647, HEL and one megakaryocyte cell line MO7 expressing erythroid markers. In this study RT-PCR was performed to evaluate VEGF expression and that of its receptor KDR; VEGF production was assayed by Elisa test and western blot analysis; sensitivity to VEGF was tested by thymidine incorporation. VEGF and its receptor KDR were expressed in B1647 and HEL, both as mRNAs and as proteins, while only KDR transcript was found in MO7 cells. Only B1647 and HEL cells showed a strong spontaneous proliferating activity. In fact, measurable amounts of VEGF were present in the unstimulated cell medium, thus suggesting an autocrine production of VEGF by B1647 and HEL cells, but not by MO7, which was inhibited in mRNA-silencing conditions. This production could not be further boosted by other growth factors, whereas it was inhibited by TGF-β1. Finally, analysis of She signal transduction proteins following stimulation with VEGF indicated that only p46 was tyrosine phosphorylated. These data indicate that leukemic cells may be capable of autocrine production of VEGF which, in turn, maintains cell proliferation, possibly mediated by She p46 phosphorylation.

Selective inhibition of growth-related gene expression in murine keratinocytes by transforming growth factor beta

1988 ◽  
Vol 8 (8) ◽  
pp. 3088-3093
Author(s):  
R J Coffey ◽  
C C Bascom ◽  
N J Sipes ◽  
R Graves-Deal ◽  
B E Weissman ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Proliferation ◽  
Growth Factor ◽  
Epithelial Cell ◽  
Transforming Growth Factor Beta ◽  
Transforming Growth Factor ◽  
Epithelial Cell Line ◽  
Tgf Beta ◽  
Growth Factor Beta ◽  
Posttranscriptional Level

Transforming growth factor beta (TGF beta) is a potent inhibitor of epithelial cell proliferation. A nontumorigenic epidermal growth factor (EGF)-dependent epithelial cell line, BALB/MK, is reversibly growth arrested by TGF beta. TGF beta will also abrogate EGF-stimulated mitogenesis of quiescent BALB/MK cells. Increased levels of calcium (greater than 1.0 mM) will induce differentiation in BALB/MK cells; in contrast, TGF beta-mediated growth inhibition does not result in induction of terminal differentiation. In the present study, the effects of TGF beta and calcium on growth factor-inducible gene expression were examined. TGF beta markedly decreased c-myc and KC gene expression in rapidly growing BALB/MK cells and reduced the EGF induction of c-myc and KC in a quiescent population of cells. TGF beta exerted its control over c-myc expression at a posttranscriptional level, and this inhibitory effect was dependent on protein synthesis. TGF beta had no effect on c-fos gene expression, whereas 1.5 mM calcium attenuated EGF-induced c-fos expression in quiescent cells. Expression of beta-actin, however, was slightly increased in both rapidly growing and EGF-restimulated quiescent BALB/MK cells treated with TGF beta. Thus, in this system, TGF beta selectively reduced expression of certain genes associated with cell proliferation (c-myc and KC), and at least part of the TGF beta effect was at a posttranscriptional level.

Regulated Hox Gene Expression Reveals a Novel Role for Hox Genes in Myeloid Cell Proliferation and Survival

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 5323-5323
Author(s):  
Marika Salmanidis ◽  
Gabi Brumatti ◽  
Anissa M Jabbour ◽  
Benjamin D Green ◽  
John Silke ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Proliferation ◽  
Cell Death ◽  
Growth Factor ◽  
Myeloid Leukaemia ◽  
Cell Lines ◽  
Hox Genes ◽  
Hox Gene ◽  
Myeloid Progenitor ◽  
Dependent Cell

Abstract The Hox family of homeodomain transcription factors are essential for the regulation of hematopoiesis and deregulated expression of some Hox gene is associated with the development of myeloproliferative disorders and leukaemia. In mammals, 39 Hox genes are organized into four clusters (A, B, C or D). The expression of these genes is tightly regulated at particular differentiation points in haematopoiesis. Importantly, the over-expression of Hox genes, HoxB4, HoxA9 and HoxA10 is frequent in acute myeloid leukaemia, and may arise as a result of MLL rearrangements or from translocations fusing Hox genes to the nucleoporin Nup98. Overexpression of murine HoxB8 together with IL-3 results in myeloid leukaemia in mice. Primary myeloid progenitor cells can be immortalised using retroviral expression of Homeobox genes HoxB8 or HoxA9 in the presence of exogenous growth factors Interleukin-3 (IL-3) or GM-CSF. We have exploited this observation to generate IL-3 dependent cell lines from gene-deleted mice to identify which members of the Bcl-2 family of apoptosis regulators are required for apoptosis provoked by IL-3 deprivation (Blood, 2006 108:1461-8). Using a unique lentiviral expression system we have now generated IL-3 dependent myeloid progenitor cell lines in which we can regulate the expression of wild-type (untagged) HoxB8 or HoxA9 using 4-hydroxy tamoxifen (4HT), to determine how these genes immortalise myeloid cells. The mechanisms of action of Hox proteins in leukaemiagenesis remain to be determined but are thought, in part at least, to result from a block in myeloid differentiation. Conditional (growth-factor dependent) immortalisation of myeloid progenitors was possible only in the presence of induced Hox gene expression and surprisingly, withdrawal of HoxB8 expression did not result in terminal differentiation of all cells. Instead, loss of Hox expression, even in the presence of IL-3, induced Go/G1 cell cycle arrest and caspase-dependent cell death. This death was substantially slower that that induced by IL-3 deprivation, indicating that for some time at least, survival signals transduced by IL-3 remained intact. Thus whilst the IL-3 survival signal persisted, the proliferative signal was inhibited. We also show that HoxB8 regulates expression of the pro-apoptotic Bcl-2 family member Bim, since loss of HoxB8 resulted in substantially increased Bim expression and the cell death induced by loss of HoxB8 expression was inhibited in Bim-deficient cells. Importantly, re-addition of 4HT to cell cultures after various periods of no HoxB8 expression restored HoxB8 expression and resulted in an increase in cell viability, cell proliferation and decrease of Bim expression, indicating that at least some cells without HoxB8 expression have not terminally differentiated and retain the ability to proliferate. Our results suggest that overexpression of Hox genes such as HoxB8 (or HoxA9) contribute to myeloid transformation by coupling a growth factor signal to proliferation and also regulate the apoptotic machinery. Using this system will be able to provide proof of principal that leukemia-associated Hox genes are valid therapeutic targets.

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