scholarly journals Metformin Enhances Nomegestrol Acetate Suppressing Growth of Endometrial Cancer Cells and May Correlate to Downregulating mTOR Activity In Vitro and In Vivo

2019 ◽  
Vol 20 (13) ◽  
pp. 3308 ◽  
Author(s):  
Can Cao ◽  
Jie-yun Zhou ◽  
Shu-wu Xie ◽  
Xiang-jie Guo ◽  
Guo-ting Li ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Endometrial Cancer ◽  
Translation Initiation Factor ◽  
Cell Counting ◽  
Initiation Factor ◽  
Antitumor Effects ◽  
Nomegestrol Acetate ◽  
Ec Cells

This study investigated the effect of a novel progestin and its combination with metformin on the growth of endometrial cancer (EC) cells. Inhibitory effects of four progestins, including nomegestrol acetate (NOMAC), medroxyprogesterone acetate, levonorgestrel, and cyproterone acetate, were evaluated in RL95-2, HEC-1A, and KLE cells using cell counting kit-8 assay. Flow cytometry was performed to detect cell cycle and apoptosis. The activity of Akt (protein kinase B), mTOR (mammalian target of rapamycin) and its downstream substrates 4EBP1 (4E-binding protein 1) and eIF4G (Eukaryotic translation initiation factor 4G) were assayed by Western blotting. Nude mice were used to assess antitumor effects in vivo. NOMAC inhibited the growth of RL95-2 and HEC-1A cells, accompanied by arresting the cell cycle at G0/G1 phase, inducing apoptosis, and markedly down-regulating the level of phosphorylated mTOR/4EBP1/eIF4G in both cell lines (p < 0.05). Metformin significantly increased the inhibitory effect of and apoptosis induced by NOMAC and strengthened the depressive effect of NOMAC on activity of mTOR and its downstream substrates, compared to their treatment alone (p < 0.05). In xenograft tumor tissues, metformin (100 mg/kg) enhanced the suppressive effect of NOMAC (100 mg/kg) on mTOR signaling and increased the average concentration of NOMAC by nearly 1.6 times compared to NOMAC treatment alone. Taken together, NOMAC suppressing the growth of EC cells likely correlates to down-regulating the activity of the mTOR pathway and metformin could strengthen this effect. Our findings open a new window for the selection of progestins in hormone therapy of EC.

scholarly journals Circadian clock control of eIF2α phosphorylation is necessary for rhythmic translation initiation

2020 ◽  
Vol 117 (20) ◽  
pp. 10935-10945 ◽  
Author(s):  
Shanta Karki ◽  
Kathrina Castillo ◽  
Zhaolan Ding ◽  
Olivia Kerr ◽  
Teresa M. Lamb ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Translation Initiation ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Nutrient Metabolism ◽  
Eif2α Phosphorylation ◽  
Eif2α Kinase ◽  
The Impact

The circadian clock in eukaryotes controls transcriptional and posttranscriptional events, including regulation of the levels and phosphorylation state of translation factors. However, the mechanisms underlying clock control of translation initiation, and the impact of this potential regulation on rhythmic protein synthesis, were not known. We show that inhibitory phosphorylation of eIF2α (P-eIF2α), a conserved translation initiation factor, is clock controlled in Neurospora crassa, peaking during the subjective day. Cycling P-eIF2α levels required rhythmic activation of the eIF2α kinase CPC-3 (the homolog of yeast and mammalian GCN2), and rhythmic activation of CPC-3 was abolished under conditions in which the levels of charged tRNAs were altered. Clock-controlled accumulation of P-eIF2α led to reduced translation during the day in vitro and was necessary for the rhythmic synthesis of select proteins in vivo. Finally, loss of rhythmic P-eIF2α levels led to reduced linear growth rates, supporting the idea that partitioning translation to specific times of day provides a growth advantage to the organism. Together, these results reveal a fundamental mechanism by which the clock regulates rhythmic protein production, and provide key insights into how rhythmic translation, cellular energy, stress, and nutrient metabolism are linked through the levels of charged versus uncharged tRNAs.

scholarly journals Hsp90 Binds and Regulates the Ligand-Inducible α Subunit of Eukaryotic Translation Initiation Factor Kinase Gcn2

1999 ◽  
Vol 19 (12) ◽  
pp. 8422-8432 ◽  
Author(s):  
Olivier Donzé ◽  
Didier Picard
Keyword(s):  
Amino Acid ◽  
Constitutive Expression ◽  
Amino Acid Starvation ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Restrictive Temperature ◽  
Α Subunit ◽  
Macbecin I

ABSTRACT The protein kinase Gcn2 stimulates translation of the yeast transcription factor Gcn4 upon amino acid starvation. Using genetic and biochemical approaches, we show that Gcn2 is regulated by the molecular chaperone Hsp90 in budding yeast Saccharomyces cerevisiae. Specifically, we found that (i) several Hsp90 mutant strains exhibit constitutive expression of a GCN4-lacZ reporter plasmid; (ii) Gcn2 and Hsp90 form a complex in vitro as well as in vivo; (iii) the specific inhibitors of Hsp90, geldanamycin and macbecin I, enhance the association of Gcn2 with Hsp90 and inhibit its kinase activity in vitro; (iv) in vivo, macbecin I strongly reduces the levels of Gcn2; (v) in a strain expressing the temperature-sensitive Hsp90 mutant G170D, both the accumulation and activity of Gcn2 are abolished at the restrictive temperature; and (vi) the Hsp90 cochaperones Cdc37, Sti1, and Sba1 are required for the response to amino acid starvation. Taken together, these data identify Gcn2 as a novel target for Hsp90, which plays a crucial role for the maturation and regulation of Gcn2.

scholarly journals Translation initiation factor 4A from Saccharomyces cerevisiae: analysis of residues conserved in the D-E-A-D family of RNA helicases.

1991 ◽  
Vol 11 (7) ◽  
pp. 3463-3471 ◽  
Author(s):  
S R Schmid ◽  
P Linder
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Translation Initiation ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Clear Correlation ◽  
Temperature Sensitive ◽  
Rna Helicases ◽  
Initiation Of Translation

The eukaryotic translation initiation factor 4A (eIF-4A) possesses an in vitro helicase activity that allows the unwinding of double-stranded RNA. This activity is dependent on ATP hydrolysis and the presence of another translation initiation factor, eIF-4B. These two initiation factors are thought to unwind mRNA secondary structures in preparation for ribosome binding and initiation of translation. To further characterize the function of eIF-4A in cellular translation and its interaction with other elements of the translation machinery, we have isolated mutations in the TIF1 and TIF2 genes encoding eIF-4A in Saccharomyces cerevisiae. We show that three highly conserved domains of the D-E-A-D protein family, encoding eIF-4A and other RNA helicases, are essential for protein function. Only in rare cases could we make a conservative substitution without affecting cell growth. The mutants show a clear correlation between their growth and in vivo translation rates. One mutation that results in a temperature-sensitive phenotype reveals an immediate decrease in translation activity following a shift to the nonpermissive temperature. These in vivo results confirm previous in vitro data demonstrating an absolute dependence of translation on the TIF1 and TIF2 gene products.

scholarly journals Binding of eukaryotic translation initiation factor 4E (eIF4E) to eIF4G represses translation of uncapped mRNA.

1997 ◽  
Vol 17 (12) ◽  
pp. 6876-6886 ◽  
Author(s):  
S Z Tarun ◽  
A B Sachs
Keyword(s):  
Translation Initiation ◽  
Mrna Translation ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Eukaryotic Translation Initiation Factor ◽  
Eukaryotic Translation ◽  
Eukaryotic Translation Initiation ◽  
Stimulation Of

mRNA translation in crude extracts from the yeast Saccharomyces cerevisiae is stimulated by the cap structure and the poly(A) tail through the binding of the cap-binding protein eukaryotic translation initiation factor 4E (eIF4E) and the poly(A) tail-binding protein Pab1p. These proteins also bind to the translation initiation factor eIF4G and thereby link the mRNA to the general translational apparatus. In contrast, uncapped, poly(A)-deficient mRNA is translated poorly in yeast extracts, in part because of the absence of eIF4E and Pab1p binding sites on the mRNA. Here, we report that uncapped-mRNA translation is also repressed in yeast extracts due to the binding of eIF4E to eIF4G. Specifically, we find that mutations which weaken the eIF4E binding site on the yeast eIF4G proteins Tif4631p and Tif4632p lead to temperature-sensitive growth in vivo and the stimulation of uncapped-mRNA translation in vitro. A mutation in eIF4E which disturbs its ability to interact with eIF4G also leads to a stimulation of uncapped-mRNA translation in vitro. Finally, overexpression of eIF4E in vivo or the addition of excess eIF4E in vitro reverses these effects of the mutations. These data support the hypothesis that the eIF4G protein can efficiently stimulate translation of exogenous uncapped mRNA in extracts but is prevented from doing so as a result of its association with eIF4E. They also suggest that some mRNAs may be translationally regulated in vivo in response to the amount of free eIF4G in the cell.

Targeting RNF8 Effectively Reverse Cisplatin and Doxorubicin Resistance in Endometrial Cancer

2020 ◽  
Author(s):  
Ben Yang ◽  
Wang Ke ◽  
Yingchun Wan ◽  
Tao Li
Keyword(s):  
Endometrial Cancer ◽  
Cell Lines ◽  
Quantitative Polymerase Chain Reaction ◽  
Mrna Levels ◽  
Mice Model ◽  
Expression Levels ◽  
Gynecological Malignancy ◽  
Ec Cells

Abstract Background Endometrial cancer (EC) is one of the most frequent gynecological malignancy worldwide. However, resistance to chemotherapy remains one of the major difficulties in the treatment of EC. Thus, there is an urgent requirement to understand mechanisms of chemoresistance and identify novel regimens for patients with EC. Methods Cisplatin and doxorubicin resistant cell lines were acquired by continuous exposing parental EC cells to cisplatin or doxorubicin for 3 months. Cell viability was determined by using MTT assay. Protein Expression levels of protein were examined by western blotting assay. mRNA levels were measured by quantitative polymerase chain reaction (qPCR) assay. Ring finger protein 8 (RNF8) knockout cell lines were generated by clustered regularly interspaced short palindromic repeats (CRISPR)–Cas9 gene editing assay. Nonhomologous end joining (NHEJ) efficiency were quantified by plasmid based NHEJ assay. DNA double strand breaks (DSB) were generated using laser micro-irradiation. Protein recruitment to DSB was analyzed by immunofluorescent assay. Tumor growth was examined by AN3CA xenograft mice model. Results We found that protein and mRNA expression levels of RNF8 were significantly increased in both cisplatin and doxorubicin resistant EC cells. Cell survival assay showed that RNF deficiency significantly enhanced the sensitivity of resistant EC cells to cisplatin and doxorubicin (P < 0.01). In addition, chemoresistant EC cells exhibited increased NHEJ efficiency. Knockout of RNF8 in chemoresistant EC cells significantly reduced NHEJ efficiency and prolonged Ku80 retention on DSB. Moreover, cisplatin resistant AN3CA xenograft showed that RNF8 deficiency overcame cisplatin resistance. Conclusions Our in vitro and in vivo assays provide evidence for RNF8, which is a NHEJ factor, serving as a promising, novel target in EC chemotherapy.

scholarly journals Coupled Release of Eukaryotic Translation Initiation Factors 5B and 1A from 80S Ribosomes following Subunit Joining

2007 ◽  
Vol 27 (6) ◽  
pp. 2384-2397 ◽  
Author(s):  
Jeanne M. Fringer ◽  
Michael G. Acker ◽  
Christie A. Fekete ◽  
Jon R. Lorsch ◽  
Thomas E. Dever
Keyword(s):  
Translation Initiation ◽  
Ribosomal Subunit ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Eukaryotic Translation ◽  
Cell Extracts ◽  
Eukaryotic Translation Initiation ◽  
Subunit Joining

ABSTRACT The translation initiation GTPase eukaryotic translation initiation factor 5B (eIF5B) binds to the factor eIF1A and catalyzes ribosomal subunit joining in vitro. We show that rapid depletion of eIF5B in Saccharomyces cerevisiae results in the accumulation of eIF1A and mRNA on 40S subunits in vivo, consistent with a defect in subunit joining. Substituting Ala for the last five residues in eIF1A (eIF1A-5A) impairs eIF5B binding to eIF1A in cell extracts and to 40S complexes in vivo. Consistently, overexpression of eIF5B suppresses the growth and translation initiation defects in yeast expressing eIF1A-5A, indicating that eIF1A helps recruit eIF5B to the 40S subunit prior to subunit joining. The GTPase-deficient eIF5B-T439A mutant accumulated on 80S complexes in vivo and was retained along with eIF1A on 80S complexes formed in vitro. Likewise, eIF5B and eIF1A remained associated with 80S complexes formed in the presence of nonhydrolyzable GDPNP, whereas these factors were released from the 80S complexes in assays containing GTP. We propose that eIF1A facilitates the binding of eIF5B to the 40S subunit to promote subunit joining. Following 80S complex formation, GTP hydrolysis by eIF5B enables the release of both eIF5B and eIF1A, and the ribosome enters the elongation phase of protein synthesis.

scholarly journals The identity and methylation status of the first transcribed nucleotide in eukaryotic mRNA 5′ cap modulates protein expression in living cells

2020 ◽  
Vol 48 (4) ◽  
pp. 1607-1626 ◽  
Author(s):  
Pawel J Sikorski ◽  
Marcin Warminski ◽  
Dorota Kubacka ◽  
Tomasz Ratajczak ◽  
Dominika Nowis ◽  
...  
Keyword(s):  
Protein Expression ◽  
Methylation Status ◽  
Structural Diversity ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
In Vitro Susceptibility ◽  
Mammalian Cell Lines ◽  
Expression Characteristic

Abstract 7-Methylguanosine 5′ cap on mRNA is necessary for efficient protein expression in vitro and in vivo. Recent studies revealed structural diversity of endogenous mRNA caps, which carry different 5′-terminal nucleotides and additional methylations (2′-O-methylation and m6A). Currently available 5′-capping methods do not address this diversity. We report trinucleotide 5′ cap analogs (m7GpppN(m)pG), which are utilized by RNA polymerase T7 to initiate transcription from templates carrying Φ6.5 promoter and enable production of mRNAs differing in the identity of the first transcribed nucleotide (N = A, m6A, G, C, U) and its methylation status (±2′-O-methylation). HPLC-purified mRNAs carrying these 5′ caps were used to study protein expression in three mammalian cell lines (3T3-L1, HeLa and JAWS II). The highest expression was observed for mRNAs carrying 5′-terminal A/Am and m6Am, whereas the lowest was observed for G and Gm. The mRNAs carrying 2′-O-methyl at the first transcribed nucleotide (cap 1) had significantly higher expression than unmethylated counterparts (cap 0) only in JAWS II dendritic cells. Further experiments indicated that the mRNA expression characteristic does not correlate with affinity for translation initiation factor 4E or in vitro susceptibility to decapping, but instead depends on mRNA purity and the immune state of the cells.

New targeted anti CDK4/6 peptide MM-D37K.

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. e13545-e13545 ◽  
Author(s):  
Vladimir Konstantinovich Bozhenko ◽  
Tatyana Michailovna Kulinich ◽  
Elena Aleksandrovna Kudinova ◽  
Andrey Boldyrev ◽  
Vladimir Alekseevich Solodkij
Keyword(s):  
Cell Cycle ◽  
Cell Lines ◽  
Full Range ◽  
Mrna Level ◽  
Xenograft Model ◽  
Specific Inhibitor ◽  
Antitumor Effects ◽  
Mcf 7

e13545 Background: MM-D37K is a synthetic peptide which consists of p16INK4a-specific inhibitor of complex cyclin D- CDK4 and CDK6 and cell penetrating peptide (CPP) – Antp (Penetratin). We investigated in vitro and in vivo cytotoxic, cytostatic and antitumor activity of MM-D37K. The level of cyclin A, Ki67,bax, bcl-2 and pRb phosphorylation was investigated. Full range of Toxicology tests and Pharmacokinetics experiments in mice, rats and rabbits were performed. Methods: Different cell lines (Jurcat, Raji, A549, MCF-7, Hct-116, Ht-29, HEK293) were incubated with 0.1-100 mM MM-D37K for 24-48 hrs. Proliferation (MTT), DNA-content, cell cycle (flow cytometry) and mRNA level of appropriate proteins (RT PCR) were investigated. In vivo experiments were conducted on xenograft model of HCT116, A-549 at concentration 5 and 10 mg/kg of MM-D37K. Toxicology experiments were made under RF Law and included 3 types of animals. LC-MS MMD37K method of detection in plasma was developed. Results: MM-D37K prevented pRb phosphorilation and proliferation activation in all investigated cell lines. Cell cycle was blocked in G1 phase. Cytostatic effect did not depend on p16 mutation or expression. MM-D37K induced apoptosis in 20-82% of investigated cells at 40 mM with lowest level for MCF-7. LD10 for rats was 100 mg/kg and no deaths were registered for rabbits (highest dose was 50 mg/kg). Concentration of MMD-37K in plasma after 2 min and bolus i.v. injection in dose 10 mg/kg was 72.16±5.64 mcg/ml. Concentration decreased in two phases. 1st – t1/2 = 2.39±0.39 min and for 2nd t1/2=2.39±0.39 hr. Antitumor effects in xenograft model were 53% for A-549 and 67% for HCT116. Conclusions: Our results proved cytotoxic, cytostatic and antitumor effects of MM-D37K in investigated cell lines in vitro and in vivo. Toxicological and pharmacokinetics results allow us recommend for I/IIa Phase clinical trial. (Support: MetaMax Ltd., RFFI, Minpromtorg RF.)

Lentivirus-Mediated RNA Interference Targeting the Long Noncoding RNA HOTAIR Inhibits Proliferation and Invasion of Endometrial Carcinoma Cells In Vitro and In Vivo

2014 ◽  
Vol 24 (4) ◽  
pp. 635-642 ◽  
Author(s):  
Jiaming Huang ◽  
Peiqi Ke ◽  
Luyan Guo ◽  
Wei Wang ◽  
Hao Tan ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Endometrial Cancer ◽  
Endometrial Carcinoma ◽  
Cancer Cells ◽  
Long Noncoding Rna ◽  
Noncoding Rna ◽  
Proliferation And Invasion

ObjectiveThe overexpression of long noncoding RNA HOTAIR is associated with various aggressive solid carcinomas. However, its relationship with endometrial carcinoma has not been reported. The present study aimed to investigate the expression of the long noncoding RNA HOTAIR in endometrial carcinoma, its relationship with the carcinoma’s clinicopathologic features, and the biological function of HOTAIR in regulating endometrial cancer cell proliferation and invasion in vitro and in vivo.MethodsThe expression of HOTAIR was detected in different tissues and cell lines by real-time PCR. Lentivirus-mediated HOTAIR-specific shRNAvectors were transfected into endometrial cancer HEC-1A cells. Cell proliferation and colony formation were examined by CCK-8 assays and colony formation assays, respectively. Invasion and migration were examined by Transwell assays. Flow cytometry assay was used to examine the cell cycle. In addition, xenograft model assays were performed to analyze the growth of endometrial cancer cells in vivo.ResultsOur data showed that HOTAIR expression was higher in endometrial cancer cells and tissues than in normal endometrial tissues. HOTAIR expression was closely related to the tumor stage (P= 0.045), myometrial invasion (P= 0.014), and lymph node metastasis (P= 0.033). The down-regulation of HOTAIR resulted in a significant inhibition of cell proliferation, migration, and invasion and in cell cycle arrest at the G0/G1 phase. Furthermore, HOTAIR depletion significantly suppressed the endometrial cancer tumorigenesis in vivo.ConclusionsThis study is the first to suggest that HOTAIR plays an important role in the carcinogenesis of endometrial cancer. Targeting HOTAIR may be a novel therapeutic strategy for endometrial cancer.

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