Homo sapiens
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ABSTRACT:
PROVIDER: PRJNA152133 | ENA |
REPOSITORIES: ENA
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Project description:By selective and reversible inhibition of CDK4/CDK6, we have developed a strategy to both inhibit proliferation and enhance cytotoxic killing of cancer cells. Induction of prolonged early-G1 arrest (pG1) by CDK4/CDK6 inhibition halts gene expression in early-G1 and prevents expression of genes programmed for other cell cycle phases. S-phase synchronization upon removal of the early-G1 block (pG1-S) fails to completely restore scheduled gene expression. Consequently, coordinate loss of IRF4 and gain of Bim and Noxa expression sensitize myeloma tumor cells to bortezomib-induced apoptosis in pG1 and more profoundly in pG1-S in vitro. Induction of pG1 and pG1-S by CDK4/CDK6 inhibition augments tumor-specific bortezomib killing in myeloma xenografts. Inhibition of CDK4/CDK6 in combination therapy thus represents a novel mechanism-based cancer therapy. PD 0332991 (PD) is the only known specific and reversible CDK4/CDK6 inhibitor. Gene expression was measured in myeloma MM1.S cells treated with PD (0.25 uM) in triplicate for 12, 24 or 36 h, or in cells released from G1, induced by 24hPD, for 4 or 18 h.
2012-04-06 | E-GEOD-35728 | biostudies-arrayexpress
Project description:By selective and reversible inhibition of CDK4/CDK6, we have developed a strategy to both inhibit proliferation and enhance cytotoxic killing of cancer cells. Induction of prolonged early-G1 arrest (pG1) by CDK4/CDK6 inhibition halts gene expression in early-G1 and prevents expression of genes programmed for other cell cycle phases. S-phase synchronization upon removal of the early-G1 block (pG1-S) fails to completely restore scheduled gene expression. Consequently, coordinate loss of IRF4 and gain of Bim and Noxa expression sensitize myeloma tumor cells to bortezomib-induced apoptosis in pG1 and more profoundly in pG1-S in vitro. Induction of pG1 and pG1-S by CDK4/CDK6 inhibition augments tumor-specific bortezomib killing in myeloma xenografts. Inhibition of CDK4/CDK6 in combination therapy thus represents a novel mechanism-based cancer therapy.
2012-04-07 | GSE35728 | GEO
Project description:Induction of Prolonged Early G1 Arrest by CDK4/CDK6 Inhibition Reprograms Lymphoma Cells for Durable PI3Kδ Inhibition Through PIK3IP1
| PRJNA202455 | ENA
Project description:CDK4/6 inhibitors arrest the cell cycle in G1-phase. They are licenced to treat breast cancer and are also undergoing clinical trials against a range of other tumour types. To facilitate these efforts, it is important to understand why a temporary cell cycle arrest in G1 causes long-lasting effects on tumour growth. Here we demonstrate that a prolonged G1-arrest following CDK4/6 inhibition downregulates replisome components and impairs origin licencing. This causes a failure in DNA replication after release from that arrest, resulting in a p53-dependent withdrawal from the cell cycle. If p53 is absent, then cells bypass the G2-checkpoint and undergo a catastrophic mitosis resulting in excessive DNA damage. These data therefore link CDK4/6 inhibition to genotoxic stress; a phenotype that is shared by most other broad-spectrum anti-cancer drugs. This provides a rationale to predict responsive tumour types and effective combination therapies, as demonstrated by the fact that chemotherapeutics that cause replication stress also induce sensitivity to CDK4/6 inhibition.
2021-12-20 | PXD023435 | Pride
Project description:The p53 tumour suppressor is a transcription factor that can regulate the expression of numerous genes encoding either proteins or microRNAs (miRNAs). The predominant outcomes of a typical p53 response are the initiation of apoptotic cascades and the activation of cell cycle checkpoints. HT29-tsp53 cells express a temperature sensitive variant of p53 and in the absence of exogenous DNA damage, these cells preferentially undergo G1 phase cell cycle arrest at the permissive temperature that correlates with increased expression of the cyclin-dependent kinase inhibitor p21WAF1. Recent evidence also suggests that a variety of miRNAs can induce G1 arrest by inhibiting the expression of proteins like CDK4 and CDK6. Here we used oligonucleotide microarrays to identify p53-regulated miRNAs that are induced in these cells undergoing G1 arrest. At the permissive temperature, the expression of several miRNAs was increased through a combination of either transcriptional or post-transcriptional regulation. In particular, miR-34a-5p, miR-143-3p and miR-145-5p were strongly induced and they reached levels comparable to that of reference miRNAs (miR-191 and miR-103). Importantly, miR-34a-5p and miR-145-5p are known to silence the Cdk4 and/or Cdk6 G1 cyclin-dependent kinases (cdks). Surprisingly, there was no p53-dependent decrease in the expression of either of these G1 cdks. To search for other potential targets of p53-regulated miRNAs, p53-downregulated mRNAs were identified through parallel microarray analysis of mRNA expression. Once again, there was no clear effect of p53 on the repression of mRNAs under these conditions despite a remarkable increase in p53-induced mRNA expression. Therefore, despite a strong p53 transcriptional response, there was no clear evidence that p53-responsive miRNA contributed to gene silencing. Taken together, the changes in cell cycle distribution in this cell line at the permissive temperature is likely attributable to transcriptional upregulation of the CDKN1A mRNA and p21WAF1 protein and not to the down regulation of CDK4 or CDK6 by p53-regulated miRNAs. Two independent experiments were performed with 2 samples in each experiment (1 control and 1 treatment condition). In the control sample, RNA was isolated cells maintained at the restrictive temperature (37ËC). The treatment treated sample, was incubated for 16 hours at the permissive temperature (32ËC).
2016-01-07 | E-GEOD-76576 | biostudies-arrayexpress
Project description:The p53 tumour suppressor is a transcription factor that can regulate the expression of numerous genes encoding either proteins or microRNAs (miRNAs). The predominant outcomes of a typical p53 response are the initiation of apoptotic cascades and the activation of cell cycle checkpoints. HT29-tsp53 cells express a temperature sensitive variant of p53 and in the absence of exogenous DNA damage, these cells preferentially undergo G1 phase cell cycle arrest at the permissive temperature that correlates with increased expression of the cyclin-dependent kinase inhibitor p21WAF1. Recent evidence also suggests that a variety of miRNAs can induce G1 arrest by inhibiting the expression of proteins like CDK4 and CDK6. Here we used oligonucleotide microarrays to identify p53-regulated miRNAs that are induced in these cells undergoing G1 arrest. At the permissive temperature, the expression of several miRNAs was increased through a combination of either transcriptional or post-transcriptional regulation. In particular, miR-34a-5p, miR-143-3p and miR-145-5p were strongly induced and they reached levels comparable to that of reference miRNAs (miR-191 and miR-103). Importantly, miR-34a-5p and miR-145-5p are known to silence the Cdk4 and/or Cdk6 G1 cyclin-dependent kinases (cdks). Surprisingly, there was no p53-dependent decrease in the expression of either of these G1 cdks. To search for other potential targets of p53-regulated miRNAs, p53-downregulated mRNAs were identified through parallel microarray analysis of mRNA expression. Once again, there was no clear effect of p53 on the repression of mRNAs under these conditions despite a remarkable increase in p53-induced mRNA expression. Therefore, despite a strong p53 transcriptional response, there was no clear evidence that p53-responsive miRNA contributed to gene silencing. Taken together, the changes in cell cycle distribution in this cell line at the permissive temperature is likely attributable to transcriptional upregulation of the CDKN1A mRNA and p21WAF1 protein and not to the down regulation of CDK4 or CDK6 by p53-regulated miRNAs.
2016-01-07 | GSE76576 | GEO
Project description:Given the intimate link between inflammation and dysregulated cell proliferation in cancer we investigated cytokine-triggered gene expression in different cell cycle stages. High density microarray analysis revealed that G1 release primes and cooperates with the cytokine-driven gene response. This effect is transmitted through CDK6 which shares the ability to regulate expression of inflammatory genes with its functional homologue CDK4. CDK6 contributes to the regulation of inflammatory gene expression by physical and functional cooperation with the NF-κB subunit p65 in the nucleus. ChIPSeq experiments showed a tight co-recruitment of CDK6 and p65 to enhancers and promoters of many transcriptionally active NF-κB target genes. While CDK6 recruitment to distinct chromatin regions of inflammatory target genes had no effect on histone modifications, it was essential for proper loading of NF-κB p65 to its cognate binding sites and for the function of p65 coactivators such as TRIP6. Furthermore, cytokine-inducible nuclear translocation and chromatin association of CDK6 depends on the kinase activity of TAK1 and p38. These results have widespread biological implications, as aberrant CDK6 expression or activation that is frequently observed in human tumors cooperates with NF-κB to shape the cytokine- and chemokine-repertoire in chronic inflammation and cancer. Four sets of experiments were performed in total (Exp1-4). Within each of these sets biological duplicates (Rep1-2) were included and analyzed. HeLa control cells or cells with established shRNA-mediated knockdown of CDK4 or CDK6 were analyzed. Cells were subjected to cell cycle arrest or were released from the arrested state for 6h. Cells were treated for 30 minutes with Interleukin-1-alpha at the arrested state or after release or were left untreated.
2013-12-31 | E-GEOD-52465 | biostudies-arrayexpress
Project description:We report a novel resistance mechanism to CDK4/6 inhibition in Hedgehog-associated medulloblastoma where cell models and mouse models demonstrate that prolonged inhibition of CDK4/6 inhibits ribosome biogenesis, activates the unfolded protein response, and increases the amount of Smoothened-activating lipids. This RNA-Sequencing dataset represents genomically-engineered mouse medulloblastoma models that either have wild-type Cdk6 or genomic knockout of Cdk6. We find that tumors that grew despite genetic loss of Cdk6 have suppresed ribosome biogenesis.
2021-01-06 | GSE164311 | GEO
Project description:Cell size and the cell cycle are intrinsically coupled and abnormal increases in cell size are associated with senescence and permanent cell cycle arrest. The mechanism by which overgrowth primes cells to withdraw from the cell cycle remains unknown. We investigate this here using CDK4/6 inhibitors that arrest cell cycle progression during G0/G1 and are used in the clinic to treat ER+/HER2- metastatic breast cancer. We demonstrate that CDK4/6 inhibition promotes cellular overgrowth during G0/G1, causing p38MAPK-p53-p21-dependent cell cycle withdrawal. We find that cell cycle withdrawal is triggered by two waves of p21 induction. First, overgrowth during a long-term G0/G1 arrest induces an osmotic stress response. This stress response produces the first wave of p21 induction. Second, when CDK4/6 inhibitors are removed, a fraction of cells escape long term G0/G1 arrest and enter S-phase where overgrowth-driven replication stress results in a second wave of p21 induction that causes cell cycle withdrawal from G2, or the subsequent G1. We propose a model whereby both waves of p21 induction contribute to promote permanent cell cycle arrest. This model could explain why cellular hypertrophy is associated with senescence and why CDK4/6 inhibitors have long-lasting effects in patients.
2023-11-27 | PXD036519 | Pride
Project description:CDK4/6 inhibitors (CDK4/6i) are effective in metastatic breast cancer, but they have been only modestly effective in most other tumor types. Here we show that tumors expressing low CDK6 rely on CDK4 function, and are exquisitely sensitive to CDK4/6i. In contrast, tumor cells expressing both CDK4 and CDK6 have increased reliance on CDK6 to ensure cell cycle progression. We discovered that CDK4/6i and CDK4/6 degraders potently bind and inhibit CDK6 selectively in tumors in which CDK6 is highly thermo-unstable and strongly associated with the HSP90/CDC37 complex. In contrast, CDK4/6i and CDK4/6 degraders are ineffective in antagonizing tumor cells expressing thermostable CDK6, due to their weaker binding to CDK6 in these cells. Thus, we uncover a general mechanism of intrinsic resistance to CDK4/6i and CDK4/6i-derived degraders and the need for novel inhibitors targeting the CDK4/6i-resistant, thermostable form of CDK6 for application as cancer therapeutics.
2022-02-16 | PXD023137 | Pride