How do small GTPase signal transduction pathways regulate cell cycle entry?

1999 ◽  
Vol 11 (6) ◽  
pp. 732-736 ◽  
Author(s):  
C MARSHALL
Keyword(s):  
Cell Cycle ◽  
Signal Transduction ◽  
Small Gtpase ◽  
Signal Transduction Pathways ◽  
Cell Cycle Entry

scholarly journals Iodide- and Glucose-Handling Gene Expression Regulated by Sorafenib or Cabozantinib in Papillary Thyroid Cancer

2015 ◽  
Vol 100 (5) ◽  
pp. 1771-1779 ◽  
Author(s):  
Maomei Ruan ◽  
Min Liu ◽  
Qianggang Dong ◽  
Libo Chen
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Signal Transduction ◽  
Cell Proliferation ◽  
Thyroid Cancer ◽  
Western Blot ◽  
Glucose Transporter ◽  
Signal Transduction Pathways ◽  
Papillary Thyroid ◽  
Cycle Arrest

Abstract Context: The aberrant silencing of iodide-handling genes accompanied by up-regulation of glucose metabolism presents a major challenge for radioiodine treatment of papillary thyroid cancer (PTC). Objective: This study aimed to evaluate the effect of tyrosine kinase inhibitors on iodide-handling and glucose-handling gene expression in BHP 2-7 cells harboring RET/PTC1 rearrangement. Main Outcome Measures: In this in vitro study, the effects of sorafenib or cabozantinib on cell growth, cycles, and apoptosis were investigated by cell proliferation assay, cell cycle analysis, and Annexin V-FITC apoptosis assay, respectively. The effect of both agents on signal transduction pathways was evaluated using the Western blot. Quantitative real-time PCR, Western blot, immunofluorescence, and radioisotope uptake assays were used to assess iodide-handling and glucose-handling gene expression. Results: Both compounds inhibited cell proliferation in a time-dependent and dose-dependent manner and caused cell cycle arrest in the G0/G1 phase. Sorafenib blocked RET, AKT, and ERK1/2 phosphorylation, whereas cabozantinib blocked RET and AKT phosphorylation. The restoration of iodide-handling gene expression and inhibition of glucose transporter 1 and 3 expression could be induced by either drug. The robust expression of sodium/iodide symporter induced by either agent was confirmed, and 125I uptake was correspondingly enhanced. 18F-fluorodeoxyglucose accumulation was significantly decreased after treatment by either sorafenib or cabozantinib. Conclusions: Sorafenib and cabozantinib had marked effects on cell proliferation, cell cycle arrest, and signal transduction pathways in PTC cells harboring RET/PTC1 rearrangement. Both agents could be potentially used to enhance the expression of iodide-handling genes and inhibit the expression of glucose transporter genes.

Synergistic Killing of Leukemic Cells by Small Molecule Inhibitors of the Pim Protein Kinases and Inactivators of Additional Signal Transduction Pathways.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 409-409
Author(s):  
Yingwei Lin ◽  
Zanna M Beharry ◽  
Elizabeth G Hill ◽  
Jin H. Song ◽  
Wenxue Wang ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Signal Transduction ◽  
Cell Growth ◽  
Small Molecule ◽  
Single Agent ◽  
Signal Transduction Pathways ◽  
Pim Kinases ◽  
Cycle Arrest ◽  
Mtorc1 Pathway ◽  
P70 S6k

Abstract Abstract 409 The serine/threonine Pim kinases are up regulated in specific hematologic neoplasms, and play an important role in key signal transduction pathways, including those regulated by c-Myc, N-Myc, FLT3-ITD, BCR-ABL, HOXA9, and EWS fusions. Pim protein kinases were first identified as a proviral integration site in c-Myc overexpressor mice and function to greatly enhance lymphoma development. Here we demonstrate that SMI-4a, a novel benzylidene-thiazolidine-2, 4-dione small molecule inhibitor of the Pim kinases supplied by Vortex Biotechnology (Mt. Pleasant, SC), kills a wide range of both myeloid and lymphoid cell lines with precursor T-cell lymphoblastic leukemia/lymphoma (pre T-LBL/T-ALL) being the most sensitive. Incubation of pre T-LBL cells with SMI-4a induced G1 phase cell cycle arrest secondary to a dose dependent induction of p27Kip1, apoptosis through the mitochondrial pathway, inhibition of mTORC1 pathway based on decreases in phosphorylation of p70 S6K and 4E-BP1, two substrates of this enzyme, and down regulation of c-myc. We demonstrate that treatment with 60 mg/kg twice daily by oral gavage of SMI-4a inhibits subcutaneous growth of pre T-LBL tumors by an average of 47.9% (p< .05) in immuno-deficient animals without notable toxicity to weight, blood counts, cell morphology, or blood chemistries. To enhance the killing effect of SMI-4a we have examined a number of potential combination therapies. First, because we find in animals and cell culture that single agent SMI-4a treatment up regulates the ERK pathway and in the spleen and thymus of Pim1/2/3 knock out mice there is increased phosphorylation of ERK1/2, we combined SMI-4a and a MEK1/2 inhibitor, U0126 or PD184352. Our results demonstrate that this combination is highly synergistic in killing pre T-LBL cells in culture. Secondly, because SMI-4a shares a number of important properties with γ-secretase inhibitors (GSI), Notch1 pathway inhibitor, including inhibition of pre T-LBL cell growth, cell cycle arrest, induction of p27Kip1, mTORC1 inhibition, and c-Myc down regulation, we tested the possibility that these agents could be synergistic. We find that single agent treatment with SMI-4a at 5 μM or treatment with the GSI Z-IL-CHO at 10 μM kills less than 20% of pre T-LBL cells, whereas in combination these drugs kill 78% of these cells, suggesting a high degree of synergy. Finally, because SMI-4a inhibits the mTORC1 pathway decreasing the phosphorylation of two mTOR substrates, p70 S6K and 4E-BP1, and because Pim plays an essential role in the FLT3/ITD signaling pathway, we examined the activity of SMI-4a with or without rapamycin in myeloid leukemic MV4-11 carrying both MLL-AF4 and FLT3-ITD and the RS4-11 cell line containing only MLL-AF4. We find that these two agents are highly synergistic in culture. SMI-4a alone inhibited growth 18% and rapamycin 40% but when combined 76% of the cell growth was blocked. SMI-4a had no effect on RS 4-11 cells. Our results demonstrate that unique combinations of a potent Pim inhibitor, SMI-4a, and small molecule blockade of either the mTORC1, ERK or Notch pathways has promise as a novel combination strategies for the treatment of human leukemia. Disclosures: No relevant conflicts of interest to declare.

Effect of Erythropoietin Treatment on Lipid Signalling Pathways in Low-Risk MDS Patients.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 2384-2384
Author(s):  
Matilde Y Follo ◽  
Sara Mongiorgi ◽  
Cristina Clissa ◽  
Francesca Chiarini ◽  
Stefania Paolini ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Signal Transduction ◽  
Rapid Evolution ◽  
Low Risk ◽  
Signalling Pathways ◽  
Signal Transduction Pathways ◽  
Akt Activation ◽  
Lipid Signalling ◽  
Gene And Protein Expression ◽  
Allelic Deletion

Abstract Abstract 2384 Poster Board II-361 Introduction: Phosphoinositide-phospholipase (PI-PLC) C beta1, PI-PLCgamma1 and Akt are key enzymes in nuclear signal transduction pathways, affecting both cell cycle and differentiation in normal physiology and neoplastic transformation. Our group previously showed not only that the Akt/mTOR axis is activated in patients with high-risk MDS (Follo MY et al, Cancer Res 2007), but also that there is an inverse correlation between PI-PLCbeta1 expression and Akt activation (Follo MY et al, Leukemia 2008). Moreover, we recently demonstrated that patients belonging to all of the IPSS risk groups can display a PI-PLCbeta1 mono-allelic deletion, and that this cytogenetic alteration is associated with a higher risk of evolution into Acute Myeloid Leukemia (AML) (Follo MY et al, J Clin Oncol 2009). Erythropoietin (EPO) is an effective treatment of anemia in 40-60% of low-risk MDS, often inducing a prolonged response. Interestingly, the activation of the EPO receptor has been correlated to the PI3K/Akt axis, which in turn is linked to either PI-PLCbeta1 or PI-PLCgamma1 signalling, so that EPO could affect cell proliferation and apoptosis. The aim of this study was therefore to clarify the relationship between EPO treatment and lipid signalling pathways, to investigate their role as molecular targets or predictive factors during EPO therapy. In fact, in patients who are refractory or lose response to EPO there could be a specific activation or inhibition of pathways involved in both cell cycle and differentiation. Patients and Methods: In this study we examined the effect of EPO treatment on lipid signal transduction pathways in MDS patients. The study included 16 patients (IPSS risk: low or intermediate-1), with a favourable response to EPO in 8/16 (50%) of the cases. For each patient we had the opportunity to analyze the expression of PI-PLCbeta1, PI-PLCgamma1, p-Akt and PIP2, which is involved in both PI-PLCbeta1 and PI3K/Akt activation processes, before and during EPO treatment, in order to detect every change in both clinical and biological features. By FISH analysis, we firstly assessed the presence of PI-PLCbeta1 mono-allelic deletion. Then, we quantified PI-PLCbeta1 and PI-PLCgamma1 gene and protein expression, as well as PIP2 and the degree of Akt activation; mRNA levels were quantified by real-time PCR, whereas the protein amount was detected by both a immunocytochemical and a flow cytometric detection approach. Results: The PI-PLCbeta1 mono-allelic deletion was found in 5/16 (31%) low-risk MDS patients: 2 of them showed a rapid evolution into AML, whilst the remaining 3 cases did not respond to EPO treatment. The molecular analyses showed a specific increase in Akt/PI-PLCgamma1 pathway for responder patients, whereas most of the patients refactory to EPO displayed a slight decrease in p-Akt levels and an activation of PI-PLCbeta1 signalling during EPO administration, so that these patients seem to counteract the lack of one PI-PLCbeta1 allele by increasing PI-PLCbeta1 gene and protein expression. Conclusions: Our results, although obtained in a small number of cases, confirm the possible involvement of PI-PLCbeta1 pathways in the EPO signalling. Moreover, our data suggest that the presence of the PI-PLCbeta1 mono-allelic deletion is associated with a worse clinical outcome and with a lack of response to EPO treatment, even in low-risk MDS patients who apparently have a good response profile for EPO (recent diagnosis, absence of long-term transfusion dependence, low or intermediate-1 IPSS risk, serum EPO levels<500 U/L). In fact, in our series, patients with the PI-PLCbeta1 mono-allelic deletion showed an unfavourable outcome (either a rapid evolution into AML or refractoriness to EPO treatment). Moreover, our findings indicate that not only PI-PLCbeta1, but also Akt/PI-PLCgamma1 pathways are critical for cell survival and proliferation in MDS patients treated with EPO. Therefore, these signal transduction pathways could become in the future an important target for the development of innovative strategies for MDS. Disclosures: Finelli: Celgene: Consultancy.

The Acquirement Of Rituximab Resistance Is Associated With De-Regulation Of The PI3K/Akt/mTOR Signaling Pathway Leading To Chemotherapy Resistance In Burkitt Lymphoma Pre-Clinical Models

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 5144-5144 ◽  
Author(s):  
Sarah Frys ◽  
Andrew Skomra ◽  
Natalie M Czuczman ◽  
Cory Mavis ◽  
Delphine C.M. Rolland ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Signal Transduction ◽  
Flow Cytometry ◽  
Cell Viability ◽  
Cell Lines ◽  
Burkitt Lymphoma ◽  
Chemotherapy Resistance ◽  
Signal Transduction Pathways ◽  
Mtor Signaling Pathway ◽  
Cycle Arrest

Abstract Treatment with multi-agent chemotherapy regimens has significantly improved survival in pediatric Burkitt Lymphoma (BL) leading to long-term survival in over 80% of cases. The incorporation of rituximab in the treatment of pediatric B-cell non-Hodgkin lymphoma (B-NHL) has been slower than in adults, but may improve clinical outcomes in high risk pediatric BL patients when combined with chemotherapy regimens. On the other hand, BL patients with primary refractory or relapsed disease have a dismal prognosis, stressing the need to identify the mechanism(s) resulting in chemotherapy/rituximab resistance and to develop novel therapeutic approaches. To this end, we exposed a BL cell line (Raji) to escalating doses of rituximab with or without human serum and generated/characterized several BL rituximab-resistant (Raji 7R and Raji 8RH) (RRCL) or rituximab-chemotherapy resistant (Raji 2R and Raji 4RH) (RCRCL) cell lines. Subsequently, we screened for aberrant activation of signal transduction pathways between RSCL (Raji), RRCL (Raji 7R and Raji 8RH), or RCRCL (Raji 2R and Raji 4RH) in an attempt to define what pathways were associated with resistance to both rituximab and chemotherapy agents. This was accomplished by the analysis of phosphorylation patterns on key-regulatory members of pre-defined signal transduction pathways using Western blotting, phospho-flow cytometry studies and phosphoproteomics. Effects on cell viability or cell cycle distribution of RRCL or RCRCL following pharmacological inhibition of key-regulatory pathways identified was then performed using the alamar blue reduction assay or flow cytometry respectively. While total Akt (Protein kinase B) expression was similar between all the types of BL cell lines tested, we found that RCRCL (Raji 2R and Raji 4RH) had an increase in basal phosphorylation levels of Akt at the Ser473 and Thr308 phosphorylation sites when compared to RSCL (Raji cells) or RRCL (Raji 7R and Raji 8RH). These findings were confirmed by phospho-flow cytometry studies. Phosphoproteomic analysis comparing Raji (RSCL) against Raji 4RH (RCRCL) cells identified an increase of at least 2 fold in the phosphorylation of 315 proteins in RCRCL including several direct targets of AKT such as GSK3B, WEE1, FOXO1 and PRAS40. Altered phosphorylation of multiple Akt/mTOR downstream proteins (BAD, 4EBP1, GSK3B and ERK) was detected by western blot in RCRCLs (Raji 2R and Raji 4RH) compared to RSCL and RRCLs. In vitro exposure of RCRCL (Raji 2R and Raji 4RH) to escalating doses of MK-2206, a selective Akt inhibitor, or idelalisib, a selective PI3 kinase delta inhibitor, resulted in a dose- and time-dependent decrease in cell viability of RCRCL and to a lesser degree RRCL and RSCL (RCRCL vs. RRCL/RSCL, p<0.05). The IC50 of MK-2206 was lower in RCRCL (Raji-2R = 2.6µM and Raji-4RH = 3.2µM) than in RSCL (Raji= 4.4µM) or RRCL (Raji 7R = 4.0µM and Raji 8RH = 5.2µM). Similarly, the IC50 for idelalisib was lower in RCRCL (Raji-2R = 61µM and Raji-4RH = 149µM) than in RSCL (Raji= 341µM) or RRCL (Raji 7R = 195µM and Raji 8RH = 318µM). In addition, PI3K/Akt/m-TOR inhibition with either MK-2206 or idelalisib induced cell cycle arrest in G1 phase in RSCL/RRCL, but G2/M cell cycle arrest was observed in RCRCL. In BL cells pre-treated with idelalisib (10µM and 50µM) for 24 hours prior to exposure to doxorubicin (1µM, 10µM or 20µM) for 48 hours, the RCRCL Raji 2R exhibited an increased sensitivity to doxorubicin compared to non-idelalisib exposed controls (untreated vs. idelalisib 10µM vs. idelalisib 50µM: doxorubicin 10µM=78% vs. 69% vs. 56%, p<0.05; doxorubicin 20µM=61% vs. 49% vs. 43%, p<0.05). Raji and Raji 7R cells pre-treated with idelalisib did not exhibit an increase in doxorubicin sensitivity. Together our data suggest that constitutive phosphorylation/activation of the PI3K/Akt signal transduction pathway is associated with the development of resistance and may play a role in shared resistant pathways that lead to the acquirement of chemotherapy resistance observed in some rituximab-resistant cell lines. Additionally, inhibition of the PI3K/Akt/mTOR pathway may partially re-sensitize chemotherapy resistant cells to the cytotoxic effects of chemotherapeutic agents. Targeting the PI3K/Akt/mTOR signaling pathway may be clinically relevant in some patients with relapsed/refractory BL. (Research supported by a grant from Hyundai Hope on Wheels and a St. Baldrick’s Foundation Scholar Award) Disclosures: Czuczman: Genetech, Onyx, Celgene, Astellas, Millennium, Mundipharma: Advisory Committees Other.

scholarly journals The DNA Damage-Induced Cell Cycle Checkpoints

2000 ◽  
Vol 2 (4) ◽  
pp. 237-243
Author(s):  
Piotr Widlak
Keyword(s):  
Cell Cycle ◽  
Signal Transduction ◽  
Dna Damage ◽  
Tumor Suppressor ◽  
Cell Cycle Progression ◽  
P53 Protein ◽  
Critical Role ◽  
Cell Cycle Checkpoints ◽  
Signal Transduction Pathways ◽  
Cycle Progression

The proliferation of eukaryotic cells is driven by a process called the cell cycle. Proper regulation of this process, leading to orderly execution of sequential steps within the cycle, ensures normal development and homeostasis of the organism. On the other hand, perturbations of the cell cycle are frequently attributed to cancer cells. Mechanisms that ensure the order and fidelity of events in the cell cycle are called checkpoints. The checkpoints induced by damaged DNA delay the cell cycle progression, providing more time for repair of lesion before DNA replication and segregation. The DNA damage-induced checkpoints can be recognized as signal transduction pathways that communicate information between DNA lesion and components of the cell cycle. Proteins involved in the cell cycle, as well as components of the signal transduction pathways communicating with the cell cycle, are frequently products of oncogenes and tumor suppressor genes. Malfunction of these genes plays a critical role in the development of human cancers. The key component in the checkpoint machinery is tumor suppressor gene p53, involved in either regulation of the cell cycle progression (e.g. Gl arrest of cells treated with DNA damaging factor) or activation of programmed cell death (apoptosis). It is postulated that p53 protein is activated by DNA damage detectors. One of the candidates for this role is DNA-dependent protein kinase (DNA-PK) which recognizes DNA strand breaks and phosphorylates p53 protein.

scholarly journals The Saccharomyces cerevisiae RanGTP-Binding Protein Msn5p Is Involved in Different Signal Transduction Pathways

Genetics ◽  
1999 ◽  
Vol 153 (3) ◽  
pp. 1219-1231
Author(s):  
Paula M Alepuz ◽  
Dina Matheos ◽  
Kyle W Cunningham ◽  
Francisco Estruch
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Signal Transduction ◽  
Signal Transduction Pathway ◽  
Small Gtpase ◽  
Signal Transduction Pathways ◽  
Phenotypic Analysis ◽  
Yeast Saccharomyces Cerevisiae ◽  
Extracellular Signals ◽  
External Conditions ◽  
Gtpase Ran

Abstract In eukaryotes, control of transcription by extracellular signals involves the translocation to the nucleus of at least one component of the signal transduction pathway. Transport through the nuclear envelope requires the activity of an import or export receptor that interacts with the small GTPase Ran. We have cloned the MSN5 gene of the yeast Saccharomyces cerevisiae that is postulated to encode one of these receptors. Msn5p belongs to a family of proteins with a conserved N-terminal sequence that acts as a RanGTP-binding domain. The results presented here provide genetic data supporting Msn5p involvement in several different signal transduction pathways. All of these pathways include changes in gene expression, and regulated nucleocytoplasmic redistribution of a component in response to external conditions has already been described in some of them. We have cloned MSN5 following two different strategies. Msn5p was constitutively localized in the nucleus. Phenotypic analysis of the msn5 mutant demonstrated that this protein participates in processes such as catabolite repression, calcium signaling, mating, and cell proliferation, as well as being involved in previously characterized phosphate utilization. Therefore, Msn5p could be a receptor for several proteins involved in different signaling pathways.

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