scholarly journals Epigenetic regulation of protein translation in KMT2A-rearranged AML

2019 ◽  
Author(s):  
Alexandra Lenard ◽  
Hongbo Michael Xie ◽  
Simone S. Riedel ◽  
Zuo-Fei Yuan ◽  
Nan Zhu ◽  
...  
Keyword(s):  
Gene Expression ◽  
Single Agent ◽  
Protein Translation ◽  
Ribosomal Gene ◽  
Clinical Activity ◽  
Protein Synthesis Inhibitor ◽  
Synthesis Inhibitor ◽  
Methyl Transferase ◽  
Antagonistic Effects ◽  
Translation Inhibitor

ABSTRACTInhibition of the histone methyl-transferase DOT1L (KMT4) has shown encouraging activity in preclinical models of KMT2A (MLL)-rearranged leukemia. The DOT1L inhibitor pinometostat (EPZ5676) was well tolerated in early phase clinical trials and showed modest clinical activity, including occasional complete responses (CRs) as single agent. These studies support the development of combinatorial therapies for KMT2A-rearranged leukemias. Here, we investigated two novel combinations: dual inhibition of the histone methyltransferases DOT1L and EZH2, and the combination of a DOT1L inhibitor with the protein synthesis inhibitor homoharringtonine (HHR).EZH2 is the catalytic histone methyltransferase in the polycomb repressive complex 2 (PRC2), and inhibition of EZH2 has reported preclinical activity in KMT2A-rearranged leukemia. We found that the H3K79 and H3K27 methyl marks are not dependent on each other, and that DOT1L and EZH2 inhibition affect largely distinct gene expression programs. In particular, the KMT2A/DOT1L target HOXA9, which is commonly de-repressed as a consequence of PRC2 loss or inhibition in other contexts, was not re-activated upon dual DOT1L/EZH2 knockout or inhibition. Despite encouraging data in murine KMT2A-MLLT3 transformed cells suggesting synergy between DOT1L and EZH2 inhibition, we found both synergistic and antagonistic effects on a panel of human KMT2A rearranged cell lines. Combinatorial inhibition of DOT1L and EZH2 is thus not a promising strategy. We identified opposing effects on ribosomal gene transcription and protein translation by DOT1L and EZH2 as a mechanism that is partially responsible for observed antagonistic effects. The effects of DOT1L inhibition on ribosomal gene expression prompted us to evaluate the combination of EPZ5676 with a protein translation inhibitor. EPZ5676 was synergistic with the protein translation inhibitor homoharringtonine (HHR), supporting further preclinical/clinical development of this combination.

Tri-iodothyronine and cycloheximide enhance insulin-like growth factor-binding protein-1 gene expression in human hepatoma cells

1993 ◽  
Vol 10 (1) ◽  
pp. 7-13 ◽  
Author(s):  
M Angervo ◽  
P Leinonen ◽  
R Koistinen ◽  
M Julkunen ◽  
M Seppälä
Keyword(s):  
Gene Expression ◽  
Thyroid Hormone ◽  
Hepatoma Cells ◽  
Protein Synthesis Inhibitor ◽  
Human Hepatoma ◽  
Human Hepatoma Cells ◽  
Synthesis Inhibitor ◽  
Genes Encoding ◽  
Protein Mediator

ABSTRACT The growth-regulating actions of IGFs are modulated by their binding proteins (IGFBPs). The serum concentration of IGFBP-1 is down-regulated by insulin, and in-vitro studies have demonstrated that IGFBP-1 secretion from various tissues and cells can be stimulated by theophylline, forskolin, oestrogen and progesterone. We have studied the effects and mechanisms of thyroid hormone action on IGFBP-1 gene expression and secretion by human hepatoma cells in vitro. Tri-iodothyronine dose-dependently enhanced IGFBP-1 secretion in serum-free HepG2 cell cultures after 24–48 h of exposure, as measured by a specific immunofluorometric assay. This was accompanied by an increase (+ 50%) in the amount of IGFBP-1 mRNA, which could be prevented by cycloheximide, a protein synthesis inhibitor. Cycloheximide transiently enhanced (+ 200%) the accumulation of IGFBP-1 mRNA at 3–12 h of incubation, when no effect of tri-iodothyronine was observed. It is concluded that thyroid hormone stimulates IGFBP-1 secretion slowly by enhancing IGFBP-1 gene expression by a protein mediator. The acute stimulation of IGFBP-1 gene transcription by cycloheximide associates this gene with a number of growth-related genes encoding growth- and tumour-associated peptides.

Upregulated JAK/STAT Signaling Represents a Major Mode of Resistance to HDAC Inhibition In Lymphoma and Provides a Rationale for Novel Combination Therapy

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 434-434 ◽  
Author(s):  
Jason Smith ◽  
Katherine J. Walsh ◽  
Cassandra L Jacobs ◽  
Qingquan Liu ◽  
Siyao Fan ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Lines ◽  
Single Agent ◽  
Acquired Resistance ◽  
Hematologic Malignancies ◽  
Cross Resistance ◽  
Clinical Activity ◽  
Molecular Pathways ◽  
Major Mode ◽  
High Degree

Abstract Abstract 434 Background Histone deacetylase inhibitors (HDACis) have demonstrated significant clinical activity in hematologic malignancies; however, single agent response rates have ranged between 20–50% with the duration of response often measured in months, suggesting that drug resistance is a major mode of failure. The pathways through which these agents work and the means by which tumors develop resistance to them are poorly understood. Combination therapy targeting multiple oncogenic pathways holds the promise to improve upon both the depth and durability of these responses. We investigated the mechanisms of inherent and acquired resistance to HDACis in a broad range of lymphomas. By detailing the molecular pathways implicated in resistance to HDACi, we sought to identify novel combinations of compounds that could overcome potential mechanisms that confer resistance. Methods and Results We tested two separate HDACis, LBH589 and SAHA in 51 cell lines representing a wide range of lymphomas including Burkitt lymphoma, diffuse large B cell lymphoma (DLBCL), mantle cell lymphoma, and Hodgkin lymphoma. Gene expression array data was generated for all these cell lines. We then identified genes that were significantly associated with resistance to both LBH589 and SAHA (p<.01) and applied hierarchical clustering to identify the functional significance of these genes. Histology was not predictive of sensitivity to either HDACi. These data were then analyzed using gene set enrichment to identify known molecular pathways associated with resistance. Activation of JAK/STAT signaling was found to be a major determinant of resistance among the cell lines that were relatively resistant to HDACi. (P<0.001, FDR <.25). To determine whether these genes that we found to be associated with resistance reflected potential mechanisms of acquired resistance to HDACi therapy, we separately engineered resistance to LBH589 and SAHA in three DLBCL cell lines (LY3, BJAB, Farage) through incremental dose escalation over a period of up to 6 months. Each of these three cell lines demonstrated sustained growth at drug concentrations that were at or above their original IC50. Each of these cell lines were then exposed to the other HDACi and tested for cross resistance. In each case, the cell lines demonstrated complete cross-resistance to the other drug. We then profiled the gene expression of these cell lines that had acquired resistance. Similar to our previous results, these cell lines demonstrated increased signaling through the JAK/STAT pathway, suggesting that mechanisms of inherent and acquired resistance are similar. We therefore reasoned that combining HDAC and JAK inhibition may overcome both inherent and acquired resistance. To investigate this hypothesis, we tested LBH589 and INCB018424, a JAK1/2 inhibitor, alone and in combination in the LY3, TMD-8, U2932, and BJAB cell lines. While INCB018424 demonstrated no single agent cytotoxicity, it yielded a high degree of synergy when combined with LBH589 with the combination index computed by the Chou-Talalay method ranging from .19 to .9. Conclusion HDACis show single agent activity in the treatment of a number of hematologic malignancies, however most patients develop resistance to these drugs after relatively short-lived remissions. Thus, the greatest promise of these drugs may lie in combination with other agents that target molecular pathways that underlie resistance to these drugs. Using gene expression profiling of a broad range of tumor types and sensitivity to HDACis we were able to identify activation of the JAK/STAT pathway as a common feature of inherent and acquired resistance to HDACis. We combined the JAK1/2 inhibitor INCB018424 with LBH589 and demonstrated a high degree of synergy. As the number of small molecule inhibitors with clinical activity increases, the need to identify rational preclinical combinations becomes greater. Pairing gene expression profiling and resistant cell lines is a promising approach to the selection of combinations likely to maximize clinical benefit while limiting toxicity. Disclosures: No relevant conflicts of interest to declare.

Transcriptional and posttranscriptional regulation of CSF-1 gene expression in human monocytes

1988 ◽  
Vol 8 (9) ◽  
pp. 3951-3954
Author(s):  
J Horiguchi ◽  
E Sariban ◽  
D Kufe
Keyword(s):  
Gene Expression ◽  
Protein Synthesis ◽  
Gene Transcription ◽  
Posttranscriptional Regulation ◽  
Drug Exposure ◽  
Actinomycin D ◽  
Protein Synthesis Inhibitor ◽  
Mrna Levels ◽  
Human Monocytes ◽  
Synthesis Inhibitor

Regulation of CSF-1 gene expression was investigated in human monocytes. CSF-1 transcripts were at low or undetectable levels in resting monocytes. However, in monocytes treated with 12-O-tetradecanoylphorbol-13-acetate (TPA), CSF-1 mRNA was increased by 3 h and reached maximal levels by 12 h of drug exposure. When nuclear run-on assays were used, CSF-1 gene transcription was also at low or undetectable levels in resting monocytes but was activated after TPA exposure. TPA-treated monocytes exposed to actinomycin D further demonstrated that the half-life of the CSF-1 mRNA is 0.9 h. The results also demonstrated that the protein synthesis inhibitor, cycloheximide (CHX), increases CSF-1 mRNA levels in both resting and TPA-treated monocytes. These effects of CHX occurred in the absence of detectable increases in CSF-1 gene transcription. Moreover, treatment of monocytes with CHX and actinomycin D demonstrated that inhibition of protein synthesis is associated with stabilization of the CSF-1 transcript. Taken together, these findings indicated that CSF-1 gene expression is controlled at both transcriptional and posttranscriptional levels in human monocytes.

Blast Phase Chronic Myeloid Leukemia: A Pooled Analysis of Subcutaneous Omacetaxine Mepesuccinate in Treatment-Resistant Patients

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3753-3753 ◽  
Author(s):  
H. Jean Khoury ◽  
Jorge E. Cortes ◽  
Meir Wetzler ◽  
Jeffrey H. Lipton ◽  
Michele Baccarani ◽  
...  
Keyword(s):  
Chronic Myeloid Leukemia ◽  
Disease Progression ◽  
Myeloid Leukemia ◽  
Research Funding ◽  
Chronic Phase ◽  
Clinical Activity ◽  
Protein Synthesis Inhibitor ◽  
Synthesis Inhibitor ◽  
Omacetaxine Mepesuccinate ◽  
Grade 3

Abstract Abstract 3753 Background Subcutaneous omacetaxine mepesuccinate (“omacetaxine”) is a first-in-class cephalotaxine. Omacetaxine is a protein synthesis inhibitor that does not depend on direct binding of Bcr-Abl. Omacetaxine reduces levels of multiple oncoproteins, including Bcr-Abl, and induces apoptosis in leukemic stem cells. Omacetaxine has shown clinical activity and adequate tolerability in two phase 2, open-label, international, multicenter studies in patients with chronic myeloid leukemia (CML): the first in patients with history of T315I mutation who had failed prior imatinib and the second in patients with resistance or intolerance to ≥2 tyrosine kinase inhibitors (TKIs). This is a pooled analysis of the efficacy and safety data of omacetaxine in patients with CML in the blast phase (BP). Methods Data from patients with CML-BP were included from two phase 2 studies. All patients received omacetaxine 1.25 mg/m2 subcutaneously twice daily for up to 14 consecutive days every 28 days for induction and the same dosage for up to 7 days every 28 days as maintenance. The number of consecutive days of dosing could be adjusted, as clinically indicated. Recombinant growth factor support was allowed in the event of febrile neutropenia. The primary outcome measures were major hematologic response (MaHR) and major cytogenetic response (MCyR). MaHR was defined as complete hematologic response (CHR) lasting ≥4 weeks, no evidence of leukemia, or return to chronic phase. MCyR included confirmed or unconfirmed complete or partial response. Secondary endpoints included duration of response, time to disease progression, overall survival and safety. Results Forty-four patients with CML-BP (median age 53.5 years [range, 19–68]) received treatment with omacetaxine. Forty-two patients (96%) had ECOG status ≤2. All but 1 patient had prior treatment with imatinib; 5 (11%) patients received imatinib only, 20 (45%) received 2 approved TKIs (imatinib, dasatinib, or nilotinib), and 19 (43%) were treated with all 3 approved TKIs. Most common non-TKI agents included hydroxyurea in 18/44 (41%), anthracyclines and related agents in 17 (39%), cytarabine in 14 (32%), and interferons in 11 (25%). Mutation analysis was not performed per protocol; however, point mutations were detected in 23 patients, and 17 (74%) of these had the T315I mutation. No mutations were identified in 7 patients and 14 were not assessed for mutations. The median number of cycles of omacetaxine administered was 2 (range 1–12) with a median duration of exposure of 1.5 months (range 0–13.8). Four patients (9%) had a MaHR (3 with CHR and 1 returned to chronic phase); additional 2 patients had hematologic improvement as a best response. No patient achieved MCyR; 3 patients (7%) achieved a minimal cytogenetic response. Median duration of MaHR was 1.7 months (range 1.7–4.9 months). Median survival was 3.5 months (95% CI 2.2–4.5); in 4 patients with MaHR, median survival was not reached as of >1 year of follow-up by Kaplan-Meier analysis (95% CI 2.4 to not reached) versus 3.5 months (95% CI 2.2–3.9) in patients without MaHR (Figure). Median time to disease progression was 2.2 months (95% CI 1.5–2.9). Grade 3/4 laboratory hematologic toxicities included thrombocytopenia (43/44 patients), anemia (36/44), neutropenia (36/44), and leukopenia (29/44), with most of the thrombocytopenia and neutropenia toxicities occurring in earlier cycles and attenuating in later cycles. The most common (≥5%) grade 3/4 nonhematologic AEs were hypercalcemia and bone pain (4/44 each), followed by confusional state (3/44). The most common reasons for discontinuation were progressive disease (21 patients) and death (14 patients); 2 patients discontinued due to AEs. One patient discontinued due to transfer for stem cell transplantation (7 cycles received on study over 6.7 months). Nineteen deaths occurred on study and 19 during follow-up; disease progression was the most common cause (25/38). One death was deemed related to the study drug (sepsis). Conclusions Among heavily pretreated patients with CML-BP who had failed prior TKI therapy, omacetaxine demonstrated limited activity, although 13% of patients had hematologic improvement, 2 patients had responses with duration longer than one year. Most grade 3/4 events were hematologic; grade 3/4 nonhematologic AEs were less common. Support: Teva Pharmaceutical Industries Ltd. Disclosures: Off Label Use: Subcutaneous omacetaxine mepesuccinate (“omacetaxine”) is a protein synthesis inhibitor that does not depend on direct binding of Bcr-Abl. Omacetaxine has shown clinical activity in 2 studies of chronic myeloid leukemia (CML), one in patients with a history of the T315I Bcr-Abl mutation and the other in patients failing at least 2 tyrosine kinase inhibitors. Cortes:Pfizer: Consultancy, Research Funding; Ariad: Consultancy, Research Funding; Chemgenex (Teva): Consultancy, Research Funding; Deciphera: Research Funding; Novartis: Consultancy, Research Funding; BMS: Consultancy, Research Funding. Wetzler:BMS: Research Funding; Teva: Membership on an entity's Board of Directors or advisory committees. Baccarani:Teva: Research Funding. Douer:Teva: Consultancy. Craig:Teva: Consultancy. Kantarjian:ChemGenex (Teva): Research Funding. Akard:Celgene: Research Funding, Speakers Bureau; Millenium: Speakers Bureau; Eisai: Speakers Bureau; Pfizer: Research Funding; Merck: Research Funding; Ariad: Research Funding; Teva: Research Funding; Bristol-Myers Squibb: Research Funding, Speakers Bureau; Novartis: Research Funding, Speakers Bureau.

scholarly journals Inhibition of hormone-sensitive lipase gene expression by cAMP and phorbol esters in 3T3-F442A and BFC-1 adipocytes

1996 ◽  
Vol 318 (3) ◽  
pp. 1057-1063 ◽  
Author(s):  
Emmanuelle PLÉE-GAUTIER ◽  
Jacques GROBER ◽  
Eric DUPLUS ◽  
Dominique LANGIN ◽  
Claude FOREST
Keyword(s):  
Gene Expression ◽  
Hormonal Regulation ◽  
Phorbol Esters ◽  
Total Activity ◽  
Hormone Sensitive Lipase ◽  
Protein Synthesis Inhibitor ◽  
Synthesis Inhibitor ◽  
Lipase Gene ◽  
Mouse Cdna ◽  
Hormone Sensitive

Hormone-sensitive lipase (HSL) catalyses the rate-limiting step in adipocyte lipolysis. Short-term hormonal regulation of HSL activity is well characterized, whereas little is known about the control of HSL gene expression. We have measured HSL mRNA content of 3T3-F442A and BFC-1 adipocytes in response to the cAMP analogue 8-(4-chlorophenylthio)-cAMP (8-CPT-cAMP) and to the phorbol ester phorbol 12-myristate 13-acetate (PMA) by Northern blot, using a specific mouse cDNA fragment. Treatment of the cells for 12 or 6 h with, respectively, 0.5 mM 8-CPT-cAMP or 1 µM PMA produced a maximal decrease of about 60% in HSL mRNA. These effects were unaffected by the protein-synthesis inhibitor anisomycin, suggesting that cAMP and PMA actions were direct. The reduction in HSL mRNA was accompanied by a reduction in HSL total activity. The intracellular routes that cAMP and PMA follow for inducing such an effect seemed clearly independent. (i) After desensitization of the protein kinase C regulation pathway by a 24 h treatment of the cells with 1 µM PMA, PMA action was abolished whereas cAMP was still fully active. (ii) Treatment with saturating concentrations of both agents produced an additive effect. (iii) The synthetic glucocorticoid dexamethasone had no proper effect on HSL gene expression but potentiated cAMP action without affecting PMA action. cAMP inhibitory action on HSL is unexpected. Indeed, the second messenger of catecholamines is the main activator of HSL by phosphorylation. We envision that a long-term cAMP treatment of adipocytes induces a counter-regulatory process that reduces HSL content and, ultimately, limits fatty acid depletion from stored triacylglycerols.

Associations Between Baseline Mutation Status and Response to Treatment with Omacetaxine Mepesuccinate in Heavily Pretreated Patients with Chronic Myeloid Leukemia

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 4433-4433
Author(s):  
Jeffrey H. Lipton ◽  
Franck E. Nicolini ◽  
Meir Wetzler ◽  
Luke Akard ◽  
Michele Baccarani ◽  
...  
Keyword(s):  
Chronic Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Research Funding ◽  
Point Mutations ◽  
Clinical Activity ◽  
Protein Synthesis Inhibitor ◽  
Synthesis Inhibitor ◽  
Two Phase ◽  
Mutation Status ◽  
Omacetaxine Mepesuccinate

Abstract Abstract 4433 Background Subcutaneous omacetaxine mepesuccinate (“omacetaxine”) is an investigational, first-in-class cephalotaxine and is a protein synthesis inhibitor that does not depend on direct binding of Bcr-Abl. Omacetaxine reduces levels of multiple oncoproteins, including Bcr-Abl, and induces apoptosis in leukemic stem cells by blocking the initial step of protein translation at the level of the ribosome. Omacetaxine has shown clinical activity and adequate tolerability in two phase 2, open-label, international, multicenter studies in patients with chronic myeloid leukemia (CML). Patients with a history of the T315I mutation who failed prior imatinib were enrolled in the first study (CML202). Patients were enrolled in the second study (CML203) if they had resistance or intolerance to ≥2 tyrosine kinase inhibitors (TKIs). Point mutations occur frequently in CML patients who develop resistance to imatinib. This is a post hoc analysis of responses to omacetaxine in patients with any phase CML by mutational status. Methods Data from patients with CML in chronic phase (CP), accelerated phase (AP), or blast phase (BP) were included from the two phase 2 studies. Omacetaxine 1.25 mg/m2was administered subcutaneously twice daily for 14 consecutive days every 28 days for induction and the same dosage for 7 days every 28 days as maintenance. An exploratory analysis was conducted to elucidate associations between mutation status and complete hematologic response (CHR) or major cytogenetic response (MCyR) following omacetaxine treatment. Results Among CP, AP, and BP patients, grade 3/4 hematologic toxicities were thrombocytopenia (in 89/105, 43/49, and 43/44 patients, respectively), neutropenia (86/106, 35/49, 36/44), leukopenia (76/106, 30/49, 29/44), and anemia (66/107, 39/49, 36/44). Common grade 3/4 nonhematologic adverse events included fatigue (5/108, 5/51, and 2/44 patients, respectively) and pneumonia (3/108, 4/51, and 2/44). Seventy-six deaths occurred during long-term follow-up (33, 24, 19); 8 were treatment-related (5, 2, 1), most commonly due to sepsis (n=3). The pooled baseline mutational analysis included 203 CML patients (108 CP, 51 AP, and 44 BP). Unknown mutations were noted in 24%, 25%, and 32% of CP, AP and BP patients, respectively. Mutations were identified in 52%, 51%, and 52% while no mutation status was recorded for 24%, 25%, and 16% of CP, AP, and BP patients, respectively. T315I was the most frequently identified mutation (Table), occurring in 36%, 24%, and 39% of patients, respectively. Multiple mutations, which include individual mutations listed separately, were detected in 12% CP, 14% AP, and 7% BP patients. Among patients with CP or AP CML, CHR rate was high in the presence of the T315I mutation. MCyR rates for CP patients were similar for patients with or without mutations but appeared to be relatively lower among patients with multiple mutations. Among AP patients, MCyR only occurred in those without mutations. Conclusions Point mutations, particularly T315I, were common in this heavily treated population of CML patients although T315I may be overrepresented due to CML202 inclusion criteria. Efficacy of omacetaxine, as measured by rates of CHR and MCyR, appeared to be largely independent of the presence or absence of point mutations. However, interpretation of these results is limited by small sample sizes in many of the groups. Support: Teva Pharmaceutical Industries Ltd. Disclosures: Off Label Use: Subcutaneous omacetaxine mepesuccinate (“omacetaxine”) is a protein synthesis inhibitor that does not depend on direct binding of Bcr-Abl. Omacetaxine has shown clinical activity in 2 studies of chronic myeloid leukemia (CML), one in patients with a history of the T315I Bcr-Abl mutation and the other in patients failing at least 2 tyrosine kinase inhibitors. Nicolini:BMS: Research Funding, Speakers Bureau; Ariad: Consultancy, Speakers Bureau; Pfizer: Consultancy; Novartis: Consultancy, Research Funding, Speakers Bureau; Teva: Speakers Bureau. Wetzler:BMS: Research Funding; Teva: Membership on an entity's Board of Directors or advisory committees. Akard:Celgene: Research Funding, Speakers Bureau; Millenium: Speakers Bureau; Eisai: Speakers Bureau; Pfizer: Research Funding; Merck: Research Funding; Ariad: Research Funding; Teva: Research Funding; Bristol-Myers Squibb: Research Funding, Speakers Bureau; Novartis: Research Funding, Speakers Bureau. Baccarani:Teva: Research Funding. Kantarjian:ChemGenex (Teva): Research Funding. Craig:Teva: Consultancy. Cortes:Chemgenex (Teva): Consultancy, Research Funding; Ariad: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Deciphera: Research Funding.

scholarly journals Transcriptional and posttranscriptional regulation of CSF-1 gene expression in human monocytes.

1988 ◽  
Vol 8 (9) ◽  
pp. 3951-3954 ◽  
Author(s):  
J Horiguchi ◽  
E Sariban ◽  
D Kufe
Keyword(s):  
Gene Expression ◽  
Protein Synthesis ◽  
Gene Transcription ◽  
Posttranscriptional Regulation ◽  
Drug Exposure ◽  
Actinomycin D ◽  
Protein Synthesis Inhibitor ◽  
Mrna Levels ◽  
Human Monocytes ◽  
Synthesis Inhibitor

Regulation of CSF-1 gene expression was investigated in human monocytes. CSF-1 transcripts were at low or undetectable levels in resting monocytes. However, in monocytes treated with 12-O-tetradecanoylphorbol-13-acetate (TPA), CSF-1 mRNA was increased by 3 h and reached maximal levels by 12 h of drug exposure. When nuclear run-on assays were used, CSF-1 gene transcription was also at low or undetectable levels in resting monocytes but was activated after TPA exposure. TPA-treated monocytes exposed to actinomycin D further demonstrated that the half-life of the CSF-1 mRNA is 0.9 h. The results also demonstrated that the protein synthesis inhibitor, cycloheximide (CHX), increases CSF-1 mRNA levels in both resting and TPA-treated monocytes. These effects of CHX occurred in the absence of detectable increases in CSF-1 gene transcription. Moreover, treatment of monocytes with CHX and actinomycin D demonstrated that inhibition of protein synthesis is associated with stabilization of the CSF-1 transcript. Taken together, these findings indicated that CSF-1 gene expression is controlled at both transcriptional and posttranscriptional levels in human monocytes.

Temporal pattern of rat small intestinal gene expression with refeeding

1994 ◽  
Vol 266 (1) ◽  
pp. G83-G89 ◽  
Author(s):  
R. A. Hodin ◽  
J. R. Graham ◽  
S. Meng ◽  
M. P. Upton
Keyword(s):  
Gene Expression ◽  
Molecular Mechanisms ◽  
Early Response ◽  
Protein Synthesis Inhibitor ◽  
Chow Diet ◽  
Intestinal Alkaline Phosphatase ◽  
Synthesis Inhibitor ◽  
Adult Rats ◽  
Fed State ◽  
Small Intestinal

Studies were carried out to elucidate the molecular mechanisms underlying small intestinal epithelial growth. Adult rats were fasted for 4 days and then refed a chow diet for up to 48 h. Histological examination confirmed the sequential occurrence of mucosal atrophy and hyperplasia. Northern blot analyses of RNA derived from small intestinal mucosal scrapings revealed a striking pattern of alterations in the expression of two different categories of genes. There were very early increases in the expression of c-fos and c-jun, reflecting the mitogenic response to refeeding that occurs within the crypt compartment. Studies using the protein synthesis inhibitor cycloheximide suggest that c-fos and c-jun are part of the “immediate-early” response of the small intestine. At later time points after the refeeding stimulus, differential changes occurred in the expression of the brush-border enzymes, lactase, and intestinal alkaline phosphatase (IAP). Refeeding caused a decrease in lactase gene expression and an increase in the expression of the 3.0-kb IAP mRNA species, reflecting a return of the villus phenotype to the normal fed state. Thus we have demonstrated a complex and temporally related pattern of gene expression within the small intestinal epithelium upon refeeding. The results provide insight into the relationship between the processes of intestinal growth and differentiation.

Apoptosis of Dedifferentiated Hepatoma Cells is Independent of NF-κB Activation in Response to LPS

2007 ◽  
Vol 27 (4-5) ◽  
pp. 235-246
Author(s):  
M. Ryan Reidy ◽  
Janette Ellis ◽  
Erin A. Schmitz ◽  
David M. Kraus ◽  
Gary A. Bulla
Keyword(s):  
Gene Expression ◽  
Cell Death ◽  
Protein Synthesis ◽  
Cell Survival ◽  
Cell Types ◽  
Hepatoma Cells ◽  
Protein Synthesis Inhibitor ◽  
Protein Synthesis Inhibitors ◽  
Synthesis Inhibitor ◽  
Dedifferentiated Hepatoma

Dedifferentiated hepatoma cells, in contrast to most other cell types including hepatoma cells, undergo apoptosis when treated with lipopolysaccharide (LPS) plus the protein synthesis inhibitor cycloheximide (CHx). We recently reported that the dedifferentiated hepatoma cells also exhibit a strong and prolonged NF-κB induction phenotype upon exposure to LPS, suggesting that NF-κB signaling may play a pro-survival role, as reported in several other cell systems. To test the role of NF-κB in preventing LPS-mediated apoptosis, we examined the dedifferentiated cell line M38. Results show that antioxidants strongly inhibited LPS + CHx-mediated cell death in the M38 cells, yet only modestly inhibited NF-κB induction. In addition, inhibition of NF-κB translocation by infection of the M38 cells with an adenoviral vector expressing an IκBα super-repressor did not result in LPS-mediated cell death. These results suggest that unlike TNFα induction, the cell survival pathway activated in response to LPS is independent of NF-κB translocation in the dedifferentiated cells. Addition of inhibitors of JNK, p38 and ERK pathways also failed to elicit LPS-mediated apoptosis similar to that observed when protein synthesis is prevented. Thus, cell survival pathways other than those involving NF-κB inducible gene expression or other well-known pathways appear to be involved in protecting the dedifferentiated hepatoma variant cells from LPS-mediated apoptosis. Importantly, this pro-apoptotic function of LPS appears to be a function of loss of hepatic gene expression, as the parental hepatoma cells resist LPS-mediated apoptosis in the presence of protein synthesis inhibitors.

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