scholarly journals Induction of Postmitotic Neuroretina Cell Proliferation by Distinct Ras Downstream Signaling Pathways

2000 ◽  
Vol 20 (19) ◽  
pp. 7068-7079 ◽  
Author(s):  
Carole Peyssonnaux ◽  
Sylvain Provot ◽  
Marie Paule Felder-Schmittbuhl ◽  
Georges Calothy ◽  
Alain Eychène
Keyword(s):  
Cell Proliferation ◽  
Cell Division ◽  
Signaling Pathways ◽  
Cell Transformation ◽  
Primary Cultures ◽  
Dominant Negative ◽  
Specific Gene ◽  
Mitogenic Effect ◽  
Downstream Signaling ◽  
Ras Effectors

ABSTRACT Ras-induced cell transformation is mediated through distinct downstream signaling pathways, including Raf, Ral-GEFs-, and phosphatidylinositol 3-kinase (PI 3-kinase)-dependent pathways. In some cell types, strong activation of the Ras–Raf–MEK–extracellular signal-regulated kinase (ERK) cascade leads to cell cycle arrest rather than cell division. We previously reported that constitutive activation of this pathway induces sustained proliferation of primary cultures of postmitotic chicken neuroretina (NR) cells. We used this model system to investigate the respective contributions of Ras downstream signaling pathways in Ras-induced cell proliferation. Three RasV12 mutants (S35, G37, and C40) which differ by their ability to bind to Ras effectors (Raf, Ral-GEFs, and the p110 subunit of PI 3-kinase, respectively) were able to induce sustained NR cell proliferation, although none of these mutants was reported to transform NIH 3T3 cells. Furthermore, they all repressed the promoter of QR1, a neuroretina growth arrest-specific gene. Overexpression of B-Raf or activated versions of Ras effectors Rlf-CAAX and p110-CAAX also induced NR cell division. The mitogenic effect of the RasC40–PI 3-kinase pathway appears to involve Rac and RhoA GTPases but not the antiapoptotic Akt (protein kinase B) signaling. Division induced by RasG37-Rlf appears to be independent of Ral GTPase activation and presumably requires an unidentified mechanism. Activation of either Ras downstream pathway resulted in ERK activation, and coexpression of a dominant negative MEK mutant or mKsr-1 kinase domain strongly inhibited proliferation induced by the three Ras mutants or by their effectors. Similar effects were observed with dominant negative mutants of Rac and Rho. Thus, both the Raf-MEK-ERK and Rac-Rho pathways are absolutely required for Ras-induced NR cell division. Activation of these two pathways by the three distinct Ras downstream effectors possibly relies on an autocrine or paracrine loop, implicating endogenous Ras, since the mitogenic effect of each Ras effector mutant was inhibited by RasN17.

scholarly journals Atypical Protein Kinase Cs Are the Ras Effectors That Mediate Repression of Myogenic Satellite Cell Differentiation

2002 ◽  
Vol 22 (4) ◽  
pp. 1140-1149 ◽  
Author(s):  
Yuri V. Fedorov ◽  
Nathan C. Jones ◽  
Bradley B. Olwin
Keyword(s):  
Skeletal Muscle ◽  
Cell Proliferation ◽  
Cell Differentiation ◽  
Cell Line ◽  
Satellite Cell ◽  
Myogenic Differentiation ◽  
Ectopic Expression ◽  
Dominant Negative ◽  
Dependent Inhibition ◽  
Ras Effectors

ABSTRACT Oncogenic Ha-Ras is a potent inhibitor of skeletal muscle cell differentiation, yet the Ras effector mediating this process remains unidentified. Here we demonstrate that the atypical protein kinases (aPKCs; λ and/or ζ) are downstream Ras effectors responsible for Ras-dependent inhibition of myogenic differentiation in a satellite cell line. First, ectopic expression of Ha-RasG12V induces translocation of PKCλ from the cytosol to the nucleus, suggesting that aPKCs are activated by Ras in myoblasts. The aPKCs function as downstream Ras effectors since inhibition of aPKCs by expression of a dominant negative PKCζ mutant or by treatment of cells with an inhibitor, GO6983, promotes myogenesis in skeletal muscle satellite cells expressing oncogenic Ha-Ras. Arresting cell proliferation synergistically enhances myogenic differentiation only when aPKCs are also inhibited. Thus, the repression of myogenic differentiation in a satellite cell line appears to be directly mediated by aPKCs acting as Ras effectors and indirectly mediated via stimulation of cell proliferation.

scholarly journals Heparanase regulates cell proliferation, apoptosis, migration and invasion of papillary thyroid carcinoma cells with multiple signaling pathways involved

2020 ◽  
Author(s):  
Chuanjia Yang ◽  
Siyang Zhang ◽  
Xiaoying Chang ◽  
Yonglian Huang ◽  
Dongxu Cui ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Papillary Thyroid Carcinoma ◽  
Thyroid Carcinoma ◽  
Signaling Pathways ◽  
Signaling Molecules ◽  
Biological Behavior ◽  
Migration And Invasion ◽  
Papillary Thyroid ◽  
Downstream Signaling ◽  
Multiple Signaling

Abstract Background Heparanase (HPSE) is an endo-β-D-glucuronidase, which is found overexpressed in various human cancers. The purpose of our work was to investigate the possible role of HPSE and the involved signaling molecules in the development of papillary thyroid carcinoma (PTC). Methods The expression of HPSE was examined in 80 samples of PTC by immunohistochemistry. In cell studies, the expression plasmid of HPSE and RNA interference with shRNA specific for HPSE were used to elucidate the effects of HPSE on proliferation, apoptosis, migration and invasion in PTC cells of B-CPAP and KTC-1. The probable downstream signaling molecules of HPSE were also explored. Results 75.0% (60 out of 80) of PTC samples was detected high expression of HPSE, which was significantly correlated with tumor size, lymph node metastasis and stage status. In cell studies, the upregulation of HPSE significantly promoted cell proliferation, migration and invasion of B-CPAP and KTC-1 cells, and interfered with cell apoptosis. On the contrary, knockdown of HPSE exhibited the opposite effects. Compared with the parental cells, HPSE silencing cells showed attenuated capabilities of proliferation, migration and invasion, yet the apoptotic rate of transfected cells was increased. The activations of various signaling molecules correlated with cell biological behavior were found to be regulated by HPSE upregulation or knockdown. Conclusions Our results suggested that HPSE probably contributed to the progression and metastasis of PTC, which were associated with multiple signaling pathways. HPSE could be a potent molecular target for the therapeutic strategy of PTC.

scholarly journals A Systematic Analysis Identifies Key Regulators Involved in Cell Proliferation and Potential Drugs for the Treatment of Human Lung Adenocarcinoma

2021 ◽  
Vol 11 ◽  
Author(s):  
Kai Wang ◽  
Man Zhang ◽  
Jiao Wang ◽  
Pan Sun ◽  
Jizhuang Luo ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Cell Division ◽  
Network Analysis ◽  
Lung Adenocarcinoma ◽  
Transcriptional Regulatory Network ◽  
Trichostatin A ◽  
Therapeutic Agents ◽  
Normal Lung ◽  
Specific Gene

Lung adenocarcinoma (LUAD) is one of the most common and malignant cancer types. Abnormal cell proliferation, exemplified by cell cycle and cell division dysregulation, is one of the most prominent hallmarks of cancer and is responsible for recurrence, metastasis, and resistance to cancer therapy. However, LUAD-specific gene regulation and clinical significance remain obscure. Here, by using both tissues and cells from LUAD and normal lung samples, 434 increased and 828 decreased genes of biological significance were detected, including 127 cell cycle-associated genes (95 increased and 32 decreased), 66 cell division-associated genes (56 increased and 10 decreased), and 81 cell proliferation-associated genes (34 increased and 47 decreased). Among them, 12 increased genes (TPX2, CENPF, BUB1, PLK1, KIF2C, AURKB, CDKN3, BUB1B, HMGA2, CDK1, ASPM, and CKS1B) and 2 decreased genes (TACC1 and MYH10) were associated with all the three above processes. Importantly, 2 (CDKN3 and CKS1B) out of the 11 increased genes (except HMGA2) are previously uncharacterized ones in LUAD and can potentially be prognostic markers. Moreover, PLK1 could be a promising therapeutic target for LUAD. Besides, protein–protein interaction network analysis showed that CDK1 and CDC20 were the hub genes, which might play crucial roles in cell proliferation of LUAD. Furthermore, transcriptional regulatory network analysis suggested that the transcription factor E2F1 could be a key regulator in controlling cell proliferation of LUAD via expression modulation of most cell cycle-, cell division-, and cell proliferation-related DEGs. Finally, trichostatin A, hycanthone, vorinostat, and mebeverine were identified as four potential therapeutic agents for LUAD. This work revealed key regulators contributing to cell proliferation in human LUAD and identified four potential therapeutic agents for treatment strategy.

scholarly journals Preproendothelin-1 expression is negatively regulated by IFNγ during hepatic stellate cell activation

2012 ◽  
Vol 302 (9) ◽  
pp. G948-G957 ◽  
Author(s):  
Tianxia Li ◽  
Zengdun Shi ◽  
Don C. Rockey
Keyword(s):  
Cell Proliferation ◽  
Mrna Expression ◽  
Signaling Pathways ◽  
Cell Activation ◽  
Stellate Cell ◽  
Intraperitoneal Administration ◽  
Stellate Cells ◽  
In Vivo Model ◽  
Specific Gene

Endothelin-1 (ET-1), a powerful vasoconstrictor peptide, is produced by activated hepatic stellate cells (HSC) and promotes cell proliferation, fibrogenesis, and contraction, the latter of which has been thought to be mechanistically linked to portal hypertension in cirrhosis. Interferon-γ (IFNγ), a Th1 cytokine produced by T cells, inhibits stellate cell proliferation, fibrogenesis, and muscle-specific gene expression. Whether IFNγ-induced inhibitory effects are linked to regulation of ET-1 expression in activated stellate cells remains unknown. Here we examined IFNγ's effects on preproET-1 mRNA expression and the signaling pathways underlying this process. We demonstrated that preproET-1 mRNA expression in HSCs was prominently increased during cell culture-induced activation; IFNγ significantly inhibited both preproET-1 mRNA expression and ET-1 peptide production. Similar results were found in an in vivo model of liver injury and intraperitoneal administration of IFNγ. PreproET-1 promoter analysis revealed that IFNγ-induced inhibition of preproET-1 mRNA expression was closely linked to the AP-1 and Smad3 signaling pathways. Furthermore, IFNγ reduced JNK phosphorylation, which tightly was associated with decreased phosphorylation of downstream factors c-Jun and Smad3 and decreased binding activity of c-Jun and Smad3 in the preprpET-1 promoter. Importantly, IFNγ reduced both c-Jun mRNA and protein levels. Given the important role of ET-1 in wound healing, our results suggest a novel negative signaling network by which IFNγ inhibits preproET-1 expression, highlighting one potential molecular mechanism for IFNγ-induced host immunomodulation of liver fibrogenesis.

scholarly journals CAPERα Is a Novel Rel-TAD-Interacting Factor That Inhibits Lymphocyte Transformation by the Potent Rel/NF-κB Oncoprotein v-Rel

2008 ◽  
Vol 82 (21) ◽  
pp. 10792-10802 ◽  
Author(s):  
Jui Dutta ◽  
Gaofeng Fan ◽  
Céline Gélinas
Keyword(s):  
Transcription Factors ◽  
Protein Interactions ◽  
Transcriptional Repression ◽  
Cell Transformation ◽  
Lymphocyte Transformation ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Specific Gene ◽  
Viral Oncoprotein ◽  
Transforming Activity

ABSTRACT The Rel/NF-κB transcription factors are constitutively activated in many human cancers. The Rel proteins in this family are implicated in leukemia/lymphomagenesis, but the mechanism is not completely understood. Previous studies showed that the transcription activation domains (TADs) of the viral oncoprotein v-Rel and its cellular Rel/NF-κB homologues c-Rel and RelA are key determinants of their different transforming activities in primary lymphocytes. Substitution of a Rel TAD for that of RelA conferred a strong transforming phenotype upon RelA, which otherwise failed to transform cells. To gain insights into protein interactions that influence cell transformation by the Rel TADs, we identified factors that interact with the TAD of v-Rel, the most oncogenic member of the Rel/NF-κB family. We report that the coactivator for transcription factors AP-1 and estrogen receptors, CAPERα, interacts with the v-Rel TAD and potently synergizes v-Rel-mediated transactivation. Importantly, coexpression of CAPERα markedly reduced and delayed v-Rel's transforming activity in primary lymphocytes, whereas a dominant-negative mutant enhanced the kinetics of v-Rel-mediated transformation. Furthermore, small interfering RNA-mediated knockdown of CAPERα in v-Rel-transformed lymphocytes significantly enhanced colony formation in soft agar. Since the potency of Rel-mediated transactivation is an important determinant of lymphocyte transformation, as is Rel's ability to induce transcriptional repression, these data suggest that CAPERα's interaction with the Rel TAD could modulate Rel/NF-κB's transforming activity by facilitating expression or dampening repression of specific gene subsets important for oncogenesis. Overall, this study identifies CAPERα as a new transcriptional coregulator for v-Rel and reveals an important role in modulating Rel's oncogenic activity.

scholarly journals Requirement for Ras/Rac1-Mediated p38 and c-Jun N-Terminal Kinase Signaling in Stat3 Transcriptional Activity Induced by the Src Oncoprotein

1999 ◽  
Vol 19 (11) ◽  
pp. 7519-7528 ◽  
Author(s):  
James Turkson ◽  
Tammy Bowman ◽  
Jalila Adnane ◽  
Yi Zhang ◽  
Julie Y. Djeu ◽  
...  
Keyword(s):  
Gene Regulation ◽  
Signaling Pathways ◽  
Transcriptional Activity ◽  
Dominant Negative ◽  
Serine Phosphorylation ◽  
Specific Gene ◽  
Kinase Signaling ◽  
Src Tyrosine Kinase ◽  
Stat3 Phosphorylation

ABSTRACT Signal transducers and activators of transcription (STATs) are transcription factors that mediate normal biologic responses to cytokines and growth factors. However, abnormal activation of certain STAT family members, including Stat3, is increasingly associated with oncogenesis. In fibroblasts expressing the Src oncoprotein, activation of Stat3 induces specific gene expression and is required for cell transformation. Although the Src tyrosine kinase induces constitutive Stat3 phosphorylation on tyrosine, activation of Stat3-mediated gene regulation requires both tyrosine and serine phosphorylation of Stat3. We investigated the signaling pathways underlying the constitutive Stat3 activation in Src oncogenesis. Expression of Ras or Rac1 dominant negative protein blocks Stat3-mediated gene regulation induced by Src in a manner consistent with dependence on p38 and c-Jun N-terminal kinase (JNK). Both of these serine/threonine kinases and Stat3 serine phosphorylation are constitutively induced in Src-transformed fibroblasts. Furthermore, inhibition of p38 and JNK activities suppresses constitutive Stat3 serine phosphorylation and Stat3-mediated gene regulation. In vitro kinase assays with purified full-length Stat3 as the substrate show that both JNK and p38 can phosphorylate Stat3 on serine. Moreover, inhibition of p38 activity and thus of Stat3 serine phosphorylation results in suppression of transformation by v-Src but not v-Ras, consistent with a requirement for Stat3 serine phosphorylation in Src transformation. Our results demonstrate that Ras- and Rac1-mediated p38 and JNK signals are required for Stat3 transcriptional activity induced by the Src oncoprotein. These findings delineate a network of tyrosine and serine/threonine kinase signaling pathways that converge on Stat3 in the context of oncogenesis.

scholarly journals Novel HSP90-PI3K Dual Inhibitor Suppresses Melanoma Cell Proliferation by Interfering with HSP90-EGFR Interaction and Downstream Signaling Pathways

2020 ◽  
Vol 21 (5) ◽  
pp. 1845 ◽  
Author(s):  
Qian Zhao ◽  
Hong-Ping Zhu ◽  
Xin Xie ◽  
Qing Mao ◽  
Yan-Qing Liu ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Signaling Pathways ◽  
Molecular Mechanisms ◽  
Migration And Invasion ◽  
Dual Inhibitor ◽  
Downstream Signaling ◽  
Cycle Arrest ◽  
Through Flow ◽  
Melanoma Xenograft

Melanoma is the deadliest form of skin cancer, and its incidence has continuously increased over the past 20 years. Therefore, the discovery of a novel targeted therapeutic strategy for melanoma is urgently needed. In our study, MTT-based cell proliferation assay, cell cycle, and apoptosis assays through flow cytometry, protein immunoblotting, protein immunoprecipitation, designing of melanoma xenograft models, and immunohistochemical/immunofluorescent assays were carried out to determine the detailed molecular mechanisms of a novel HSP90-PI3K dual inhibitor. Our compound, named DHP1808, was found to suppress A375 cell proliferation through apoptosis induction by activating the Fas/FasL signaling pathway; it also induced cell-cycle arrest and inhibited the cell migration and invasion of A375 cells by interfering with Hsp90-EGFR interactions and downstream signaling pathways. Our results indicate that DHP1808 could be a promising lead compound for the Hsp90/PI3K dual inhibitor.

scholarly journals Stat3 Activation by Src Induces Specific Gene Regulation and Is Required for Cell Transformation

1998 ◽  
Vol 18 (5) ◽  
pp. 2545-2552 ◽  
Author(s):  
James Turkson ◽  
Tammy Bowman ◽  
Roy Garcia ◽  
Eric Caldenhoven ◽  
Rolf P. De Groot ◽  
...  
Keyword(s):  
Gene Expression ◽  
Gene Regulation ◽  
Signaling Pathways ◽  
Cell Transformation ◽  
Specific Gene ◽  
3T3 Cells ◽  
Focus Formation ◽  
Stat3 Signaling ◽  
Nih 3T3 ◽  
Nih 3T3 Cells

ABSTRACT While signal transducers and activators of transcription (STATs) were originally discovered as intracellular effectors of normal signaling by cytokines, increasing evidence also points to a role for STAT transcription factors in oncogenesis. Previous studies have demonstrated that one STAT family member, Stat3, possesses constitutively elevated tyrosine phosphorylation and DNA-binding activity in fibroblasts stably transformed by the Src oncoprotein. To determine if this Stat3 activation by Src could induce Stat3-mediated gene expression, luciferase reporter constructs based on synthetic and authentic promoters were transfected into NIH 3T3 cells. Activation of endogenous cellular Stat3 by the Src oncoprotein induced gene expression through a Stat3-specific binding element (TTCCCGAA) of the C-reactive protein gene promoter. A naturally occurring splice variant of human Stat3 protein, Stat3β, with a deletion in the C-terminal transactivation domain abolished this gene induction in a dominant negative manner. Expression of Stat3β did not have any effect on a reporter construct based on the c-fos serum response element, which is not dependent on Stat3 signaling, indicating that Stat3β does not nonspecifically inhibit other signaling pathways or Src function. Transfection of vectors expressing Stat3β together with Src blocked cell transformation by Src as measured in a quantitative focus formation assay using NIH 3T3 cells. By contrast, Stat3β had a much less pronounced effect on focus formation induced by the Ras oncoprotein, which does not activate Stat3 signaling. In addition, three independent clones of NIH 3T3 cells stably overexpressing Stat3β were generated and characterized, demonstrating that Stat3β overexpression does not have a toxic effect on cell viability. These Stat3β-overexpressing clones were shown to be deficient in Stat3-mediated signaling and refractory to Src-induced cell transformation. We conclude that Stat3 activation by the Src oncoprotein leads to specific gene regulation and that Stat3 is one of the critical signaling pathways involved in Src oncogenesis. Our findings provide evidence that oncogenesis-associated activation of Stat3 signaling is part of the process of malignant transformation.

scholarly journals Heat shock factor 1 suppression induces spindle abnormalities and sensitizes cells to antimitotic drugs

Cell Division ◽  
2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Hsiao-Hui Kuo ◽  
Zhi-Rou Su ◽  
Jing-Yuan Chuang ◽  
Ling-Huei Yih
Keyword(s):  
Cell Proliferation ◽  
Cell Death ◽  
Heat Shock ◽  
Cell Transformation ◽  
Heat Shock Factor ◽  
Dominant Negative ◽  
Heat Shock Factor 1 ◽  
Mitotic Spindles ◽  
Drug Induced ◽  
Transactivation Activity

Abstract Background Heat shock factor 1 (HSF1) is the master regulator of the heat shock response and supports malignant cell transformation. Recent work has shown that HSF1 can access the promoters of heat shock proteins (HSPs) and allow HSP expression during mitosis. It also acts as a mitotic regulator, controlling chromosome segregation. In this study, we investigated whether the transactivation activity of HSF1 is required for the assembly of mitotic spindles. Results Our results showed that phosphorylation of HSF1 at serine 326 (S326) and its transactivation activity were increased during mitosis. Inhibition of the transactivation activity of HSF1 by KRIBB11 or CCT251263 during mitosis significantly increased the proportion of mitotic cells with abnormal spindles. It also hampered the reassembly of spindle microtubules after nocodazole treatment and washout by impeding the formation of chromosomal microtubule asters. Depletion of HSF1 led to defects in mitotic spindle assembly, subsequently attenuating cell proliferation and anchorage-independent cell growth (AIG). These HSF1 depletion-induced effects could be rescued by ectopically expressing wild-type HSF1 or a constitutively active mutant (∆202-316, caHSF1) but not the S326A or dominant negative (∆361-529, dnHSF1) mutants. In addition, overexpression of HSP70 partially reduced HSF1 depletion-induced spindle abnormalities. These results indicate that HSF1 may support cell proliferation and AIG by maintaining spindle integrity through its transactivation activity. Furthermore, inhibition of HSF1 transactivation activity by KRIBB11 or CCT251236 can enhance diverse anti-mitosis drug-induced spindle defects and cell death. Conclusions The increased transactivation activity of HSF1 during mitosis appears to be required for accurate assembly of mitotic spindles, thereby supporting cell viability and probably AIG. In addition, inhibition of the transactivation activity of HSF1 may enhance the mitotic errors and cell death induced by anti-mitosis drugs.

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