Flavopiridol Down-Regulates Genes Involved in Cell Cycle Regulation and Tumor Progression in Adults with Refractory or Poor-Risk Acute Leukemia.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 953-953 ◽  
Author(s):  
Linda Resar ◽  
Joelle Hillion ◽  
Katrina Alino ◽  
Michelle Rudek ◽  
Judith Karp
Keyword(s):  
Cell Cycle ◽  
Acute Leukemia ◽  
Rna Polymerase ◽  
Cyclin D1 ◽  
Rna Polymerase Ii ◽  
Target Genes ◽  
Mrna Levels ◽  
Cyclin Dependent Kinase ◽  
Poor Risk ◽  
Before And After

Abstract Acute leukemia in adults continues to be a formidable clinical challenge that demands further investigation to identify more rational therapies. To optimize anti-leukemia therapy, we are investigating the prototypical cyclin dependent kinase (cdk) inhibitor, flavopiridol, in refractory or poor-risk disease. Flavopiridol is a cytotoxic molecule that is thought to induce cell cycle arrest by blocking cyclin-dependent kinase (cdk) function, thereby interfering with RNA Polymerase II activity and globally down-regulating gene expression. In the setting of pan-cdk inhibition, E2F1 is released and appears to drive apoptosis in transformed cells. Consistent with these proposed mechanisms of action, a previous study from our group showed that flavopiridol induces apoptosis in vitro in leukemic blasts from patients with refractory leukemia. Administration of flavopiridol was associated with a decrease in one or more of the following proteins in the leukemic blasts: RNA Polymerase II, STAT3, cyclin D1, Bcl-2, and Mcl-1. Serum VEGF levels also decreased in most patients. We are now investigating mRNA levels of the genes encoding these proteins by quantitative, RT-PCR in leukemic blasts from adult patients with refractory or poor-risk leukemia before and after flavopiridol therapy. We have treated 26 patients with flavopiridol at an escalating, hybrid dose followed by ara-c and mitxantrone. Adequate RNA from leukemic blasts before and after flavopiridol administration was available from 8 of 11 patients studied thus far. All cases (8/8) exhibit a marked decrease in mRNA for VEGF following flavopiridol. mRNA levels for other putative flavopiridol target genes is also decreased in a subset of leukemic blast samples after therapy, as follows: E2F1 (6/8), STAT3 (6/8), Mcl-1 (6/8), RNA Polymerase subunit 2a (3/3), and cyclin D1 (2/3). In contrast, bcl-2 mRNA levels increased after flavopiridol in most cases (7/8), which could represent a compensatory mechanism of leukemic blasts to avoid apoptotic cell death. Our preliminary studies indicate that flavopiridol is cytotoxic in poor-risk and refractory acute leukemia. Studies are underway to determine if down-regulation of any putative target genes correlates with pharmacologic data or clinical responses.

scholarly journals Cell cycle-dependent regulation of RNA polymerase II basal transcription activity

1995 ◽  
Vol 23 (20) ◽  
pp. 4050-4054 ◽  
Author(s):  
Masatomo Yonaha ◽  
Taku Chibazakura ◽  
Shigetaka Kitajima ◽  
Yukio Yasukochi
Keyword(s):  
Cell Cycle ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Basal Transcription ◽  
Transcription Activity ◽  
Cycle Dependent

scholarly journals Joint changes in RNA, RNA polymerase II, and promoter activity through the cell cycle identify non-coding RNAs involved in proliferation

2021 ◽  
Author(s):  
Siv Anita Hegre ◽  
Helle Samdal ◽  
Antonin Klima ◽  
Endre B. Stovner ◽  
Kristin G. Nørsett ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Promoter Activity ◽  
Cycle Phase ◽  
Specific Expression ◽  
Chip Sequencing ◽  
Non Coding Rnas ◽  
Cycle Dependent ◽  
Rna Levels

AbstractProper regulation of the cell cycle is necessary for normal growth and development of all organisms. Conversely, altered cell cycle regulation often underlies proliferative diseases such as cancer. Long non-coding RNAs (lncRNAs) are recognized as important regulators of gene expression and are often found dysregulated in diseases, including cancers. However, identifying lncRNAs with cell cycle functions is challenging due to their often low and cell-type specific expression. We present a highly effective method that analyses changes in promoter activity, transcription, and RNA levels for identifying genes enriched for cell cycle functions. Specifically, by combining RNA sequencing with ChIP sequencing through the cell cycle of synchronized human keratinocytes, we identified 1009 genes with cell cycle-dependent expression and correlated changes in RNA polymerase II occupancy or promoter activity as measured by histone 3 lysine 4 trimethylation (H3K4me3). These genes were highly enriched for genes with known cell cycle functions and included 59 lncRNAs. We selected four of these lncRNAs – AC005682.5, RP11-132A1.4, ZFAS1, and EPB41L4A-AS1 – for further experimental validation and found that knockdown of each of the four lncRNAs affected cell cycle phase distributions and reduced proliferation in multiple cell lines. These results show that many genes with cell cycle functions have concomitant cell-cycle dependent changes in promoter activity, transcription, and RNA levels and support that our multi-omics method is well suited for identifying lncRNAs involved in the cell cycle.

scholarly journals Minireview: Cyclin D1: Normal and Abnormal Functions

Endocrinology ◽  
2004 ◽  
Vol 145 (12) ◽  
pp. 5439-5447 ◽  
Author(s):  
Maofu Fu ◽  
Chenguang Wang ◽  
Zhiping Li ◽  
Toshiyuki Sakamaki ◽  
Richard G. Pestell
Keyword(s):  
Cell Cycle ◽  
Cyclin D1 ◽  
Chromatin Remodeling ◽  
Original Description ◽  
Cellular Migration ◽  
Regulatory Subunit ◽  
Cyclin Dependent Kinase ◽  
Fat Cell ◽  
Independent Functions ◽  
Cancer Côlon

Abstract Cyclin D1 encodes the regulatory subunit of a holoenzyme that phosphorylates and inactivates the retinoblastoma protein and promotes progression through the G1-S phase of the cell cycle. Amplification or overexpression of cyclin D1 plays pivotal roles in the development of a subset of human cancers including parathyroid adenoma, breast cancer, colon cancer, lymphoma, melanoma, and prostate cancer. Of the three D-type cyclins, each of which binds cyclin-dependent kinase (CDK), it is cyclin D1 overexpression that is predominantly associated with human tumorigenesis and cellular metastases. In recent years accumulating evidence suggests that in addition to its original description as a CDK-dependent regulator of the cell cycle, cyclin D1 also conveys cell cycle or CDK-independent functions. Cyclin D1 associates with, and regulates activity of, transcription factors, coactivators and corepressors that govern histone acetylation and chromatin remodeling proteins. The recent findings that cyclin D1 regulates cellular metabolism, fat cell differentiation and cellular migration have refocused attention on novel functions of cyclin D1 and their possible role in tumorigenesis. In this review, both the classic and novel functions of cyclin D1 are discussed with emphasis on the CDK-independent functions of cyclin D1.

scholarly journals PPARβ/δ recruits NCOR and regulates transcription reinitiation of ANGPTL4

2019 ◽  
Vol 47 (18) ◽  
pp. 9573-9591 ◽  
Author(s):  
Nathalie Legrand ◽  
Clemens L Bretscher ◽  
Svenja Zielke ◽  
Bernhard Wilke ◽  
Michael Daude ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Nuclear Receptor ◽  
Transcription Initiation ◽  
Target Gene ◽  
Target Genes ◽  
Hdac Inhibition ◽  
Inverse Agonists ◽  
Transcription Reinitiation

Abstract In the absence of ligands, the nuclear receptor PPARβ/δ recruits the NCOR and SMRT corepressors, which form complexes with HDAC3, to canonical target genes. Agonistic ligands cause dissociation of corepressors and enable enhanced transcription. Vice versa, synthetic inverse agonists augment corepressor recruitment and repression. Both basal repression of the target gene ANGPTL4 and reinforced repression elicited by inverse agonists are partially insensitive to HDAC inhibition. This raises the question how PPARβ/δ represses transcription mechanistically. We show that the PPARβ/δ inverse agonist PT-S264 impairs transcription initiation by decreasing recruitment of activating Mediator subunits, RNA polymerase II, and TFIIB, but not of TFIIA, to the ANGPTL4 promoter. Mass spectrometry identifies NCOR as the main PT-S264-dependent interactor of PPARβ/δ. Reconstitution of knockout cells with PPARβ/δ mutants deficient in basal repression results in diminished recruitment of NCOR, SMRT, and HDAC3 to PPAR target genes, while occupancy by RNA polymerase II is increased. PT-S264 restores binding of NCOR, SMRT, and HDAC3 to the mutants, resulting in reduced polymerase II occupancy. Our findings corroborate deacetylase-dependent and -independent repressive functions of HDAC3-containing complexes, which act in parallel to downregulate transcription.

scholarly journals Postrecruitment Regulation of RNA Polymerase II Directs Rapid Signaling Responses at the Promoters of Estrogen Target Genes

2008 ◽  
Vol 29 (5) ◽  
pp. 1123-1133 ◽  
Author(s):  
Miltiadis Kininis ◽  
Gary D. Isaacs ◽  
Leighton J. Core ◽  
Nasun Hah ◽  
W. Lee Kraus
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Target Genes ◽  
Elongation Factor ◽  
Estrogen Signaling ◽  
Gene Promoters ◽  
Pol Ii ◽  
Activator Proteins ◽  
Classical Models ◽  
Target Promoters

ABSTRACT Under classical models for signal-dependent transcription in eukaryotes, DNA-binding activator proteins regulate the recruitment of RNA polymerase II (Pol II) to a set of target promoters. However, recent studies, as well as our results herein, show that Pol II is widely distributed (i.e., “preloaded”) at the promoters of many genes prior to specific signaling events. How Pol II recruitment and Pol II preloading fit within a unified model of gene regulation is unclear. In addition, the mechanisms through which cellular signals activate preloaded Pol II across mammalian genomes remain largely unknown. We show here that the predominant genomic outcome of estrogen signaling is the postrecruitment regulation of Pol II activity at target gene promoters, likely through specific changes in Pol II phosphorylation rather than through recruitment of Pol II to the promoters. Furthermore, we show that negative elongation factor binds to estrogen target promoters in conjunction with preloaded Pol II and represses gene expression until the appropriate signal is received. Finally, our studies reveal that the estrogen-dependent activation of preloaded Pol II facilitates rapid gene regulatory responses which play important physiological roles in regulating estrogen signaling itself. Our results reveal a broad use of postrecruitment Pol II regulation by the estrogen signaling pathway, a mode of regulation that is likely to apply to a wide variety of signal-regulated pathways.

scholarly journals Both estrogen and raloxifene cause G1 arrest of vascular smooth muscle cells

2003 ◽  
Vol 178 (2) ◽  
pp. 319-329 ◽  
Author(s):  
K Takahashi ◽  
M Ohmichi ◽  
M Yoshida ◽  
K Hisamoto ◽  
S Mabuchi ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Cyclin D1 ◽  
Vascular Smooth Muscle Cells ◽  
Muscle Cells ◽  
G1 Arrest ◽  
Cyclin Dependent Kinase ◽  
Inhibitory Effects

The proliferation of vascular smooth muscle cells (VSMC) is a crucial pathophysiological process in the development of atherosclerosis. Although estrogen is known to inhibit the proliferation of VSMC, the mechanism responsible for this effect remains to be elucidated. In addition, the effect of raloxifene on VSMC remains unknown. We have shown here that 17beta-estradiol (E(2)) and raloxifene significantly inhibited the platelet-derived growth factor (PDGF)-stimulated proliferation of cultured human VSMC. Flow cytometry demonstrated that PDGF-stimulated S-phase progression of the cell cycle in VSMC was also suppressed by E(2) or raloxifene. We found that PDGF-induced phosphorylation of retinoblastoma protein (pRb), whose hyperphosphorylation is a hallmark of the G1-S transition in the cell cycle, was significantly inhibited by E(2) and raloxifene. These effects were associated with a decrease in cyclin D1 expression, without a change in cyclin-dependent kinase 4 or cyclin-dependent kinase inhibitor, p27(kip1) expression. ICI 182,780 abolished the inhibitory effects of E(2) and raloxifene on PDGF-induced pRb phosphorylation. Next, we examined which estrogen receptor (ER) is necessary for these effects of E(2) and raloxifene. Since VSMC express both ERalpha and ERbeta, A10, a rat aortic smooth muscle cell line that expresses ERbeta but not ERalpha, was used. The dose-dependent stimulation of A10 cell proliferation by PDGF was not inhibited by E(2) or raloxifene in contrast to the results obtained in VSMC. Moreover, E(2) and raloxifene significantly inhibited the PDGF-induced cyclin D1 promoter activity in A10 cells transfected with cDNA for ERalpha but not in the parental cells. These results suggested that E(2) and raloxifene exert an antiproliferative effect in VSMC treated with PDGF, at least in part through inhibition of pRb phosphorylation, and that the inhibitory effects of E(2) and raloxifene may be mainly mediated by ERalpha.

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