Identification of genes responsible for RelA-dependent proliferation arrest in HMEC conditionally expressing RelA
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE65040 | GEO | 2015/09/26
SECONDARY ACCESSION(S): PRJNA272772
REPOSITORIES: GEO
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Project description:Genomic aberrations of Cyclin D1 (CCND1) and CDK4 in neuroblastoma indicate that dysregulation of the G1 entry checkpoint is an important cell cycle aberration in this pediatric tumor. Here we report that analysis of Affymetrix expression data of primary neuroblastic tumors shows an extensive over-expression of Cyclin D1 and CDK4 which correlates with histological subgroups and prognosis respectively. Immunohistochemical analysis demonstrated an over-expression of Cyclin D1 in neuroblasts and a low Cyclin D1 expression in all cell types in ganglioneuroma. This suggests an involvement of G1 regulating genes in neuronal differentiation processes which we further evaluated using RNA interference against Cyclin D1 and its kinase partner CDK4 in several neuroblastoma cell lines. This resulted in pRb pathway inhibition as shown by an almost complete disappearance of CDK4 specific pRb phosphorylation; reduction of E2F transcriptional activity and a decrease of Cyclin A protein levels. The Cyclin D1 and CDK4 knock-down resulted in a significant reduction in cell proliferation, a G1 specific cell cycle arrest and moreover an extensive neuronal differentiation. Affymetrix microarray profiling of siRNA treated cells revealed a shift in expression profile towards a neuronal phenotype. Several new potential downstream players are identified. We conclude that neuroblastoma functionally depend on over-expression of G1 regulating genes to maintain their undifferentiated phenotype. Experiment Overall Design: The Cell line IMR-32 at time point 0 and transiently transfected with siRNA against GFP, Cyclin D1 and CDK4 at time point 48 hours. All experiments are biological triplicates.
2008-10-25 | E-GEOD-8866 | biostudies-arrayexpress
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:Genomic aberrations of Cyclin D1 (CCND1) and CDK4 in neuroblastoma indicate that dysregulation of the G1 entry checkpoint is an important cell cycle aberration in this pediatric tumor. Here we report that analysis of Affymetrix expression data of primary neuroblastic tumors shows an extensive over-expression of Cyclin D1 and CDK4 which correlates with histological subgroups and prognosis respectively. Immunohistochemical analysis demonstrated an over-expression of Cyclin D1 in neuroblasts and a low Cyclin D1 expression in all cell types in ganglioneuroma. This suggests an involvement of G1 regulating genes in neuronal differentiation processes which we further evaluated using RNA interference against Cyclin D1 and its kinase partner CDK4 in several neuroblastoma cell lines. This resulted in pRb pathway inhibition as shown by an almost complete disappearance of CDK4 specific pRb phosphorylation; reduction of E2F transcriptional activity and a decrease of Cyclin A protein levels. The Cyclin D1 and CDK4 knock-down resulted in a significant reduction in cell proliferation, a G1 specific cell cycle arrest and moreover an extensive neuronal differentiation. Affymetrix microarray profiling of siRNA treated cells revealed a shift in expression profile towards a neuronal phenotype. Several new potential downstream players are identified. We conclude that neuroblastoma functionally depend on over-expression of G1 regulating genes to maintain their undifferentiated phenotype. Keywords: Neuroblastoma, CCND1, Cyclin D1, CDK4
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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.
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