Transcription profiling of human AML cell lines treated with rapamycin treatment - evidence for Skp2 and p27 mediated G1 arrest
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
SUBMITTER: Karthik Narasimhan
PROVIDER: E-MEXP-2170 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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Project description:This SuperSeries is composed of the SubSeries listed below. Refer to individual Series
2015-07-12 | E-GEOD-67924 | biostudies-arrayexpress
Project description:SCF-Skp2 E3 ubiquitin ligase (Skp2 hereafter) targets several cell cycle regulatory proteins for degradation via the ubiquitin-dependent pathway. However, the target-specific physiological functions of Skp2 have not been fully elucidated in kidney diseases. We previously reported an increase in Skp2 in progressive nephropathy and amelioration of unilateral ureteral obstruction (UUO) renal injury associated with renal accumulation of p27 in Skp2(-/-) mice. However, it remains unclear whether the amelioration of renal injury in Skp2(-/-) mice is solely caused by p27 accumulation, since Skp2 targets several other proteins. Using Skp2(-/-)p27(-/-) mice, we investigated whether Skp2 specifically targets p27 in the progressive nephropathy mediated by UUO. In contrast to the marked suppression of UUO renal injury in Skp2(-/-) mice, progression of tubular dilatation associated with tubular epithelial cell proliferation and tubulointerstitial fibrosis with increased expression of collagen and ?-smooth muscle actin were observed in the obstructed kidneys in Skp2(-/-)p27(-/-) mice. No significant increases in other Skp2 target proteins including p57, p130, TOB1, cyclin A and cyclin D1 were noted in the UUO kidney in Skp2(-/-) mice, while p21, c-Myc, b-Myb and cyclin E were slightly increased. Contrary to the ameliorated UUO renal injure by Skp2-deficiency, the amelioration was canceled by the additional p27-deficiency in Skp2(-/-)p27(-/-) mice. These findings suggest a pathogenic role of the reduction in p27 targeted by Skp2 in the progression of nephropathy in UUO mice.
| S-EPMC3338689 | biostudies-literature
Project description:Decreased p27(Kip1) levels are a poor prognostic factor in many malignancies, and can occur through up-regulation of SCF(Skp2) E3 ligase function, resulting in enhanced p27 ubiquitination and proteasome-mediated degradation. While proteasome inhibitors stabilize p27(Kip1), agents inhibiting SCF(Skp2) may represent more directly targeted drugs with the promise of enhanced efficacy and reduced toxicity. Using high-throughput screening, we identified Compound A (CpdA), which interfered with SCF(Skp2) ligase function in vitro, and induced specific accumulation of p21 and other SCF(Skp2) substrates in cells without activating a heat-shock protein response. CpdA prevented incorporation of Skp2 into the SCF(Skp2) ligase, and induced G(1)/S cell-cycle arrest as well as SCF(Skp2)- and p27-dependent cell killing. This programmed cell death was caspase-independent, and instead occurred through activation of autophagy. In models of multiple myeloma, CpdA overcame resistance to dexamethasone, doxorubicin, and melphalan, as well as to bortezomib, and also acted synergistically with this proteasome inhibitor. Importantly, CpdA was active against patient-derived plasma cells and both myeloid and lymphoblastoid leukemia blasts, and showed preferential activity against neoplastic cells while relatively sparing other marrow components. These findings provide a rational framework for further development of SCF(Skp2) inhibitors as a novel class of antitumor agents.
| S-EPMC2343599 | biostudies-literature
Project description:This SuperSeries is composed of the SubSeries listed below. Refer to individual Series
2016-07-01 | E-GEOD-71544 | biostudies-arrayexpress
Project description:MYC is a pleiotropic transcription factor that controls a number of fundamental cellular processes required for the proliferation and survival of normal and malignant cells, including the cell cycle. MYC interacts with several central cell cycle regulators that control the balance between cell cycle progression and temporary or permanent cell cycle arrest (cellular senescence). Among these are the cyclin E/A/cyclin-dependent kinase 2 (CDK2) complexes, the CDK inhibitor p27KIP1 (p27) and the E3 ubiquitin ligase component S-phase kinase-associated protein 2 (SKP2), which control each other by forming a triangular network. MYC is engaged in bidirectional crosstalk with each of these players; while MYC regulates their expression and/or activity, these factors in turn modulate MYC through protein interactions and post-translational modifications including phosphorylation and ubiquitylation, impacting on MYC's transcriptional output on genes involved in cell cycle progression and senescence. Here we elaborate on these network interactions with MYC and their impact on transcription, cell cycle, replication and stress signaling, and on the role of other players interconnected to this network, such as CDK1, the retinoblastoma protein (pRB), protein phosphatase 2A (PP2A), the F-box proteins FBXW7 and FBXO28, the RAS oncoprotein and the ubiquitin/proteasome system. Finally, we describe how the MYC/CDK2/p27/SKP2 axis impacts on tumor development and discuss possible ways to interfere therapeutically with this system to improve cancer treatment.
| S-EPMC5541307 | biostudies-other
Project description:In the ubiquitin proteasome system, the E3 ligase SCF-Skp2 and its accessory protein, Cks1, promote proliferation largely by inducing the degradation of the CDK inhibitor p27. Overexpression of Skp2 in human cancers correlates with poor prognosis, and deregulation of SCF-Skp2-Cks1 promotes tumorigenesis in animal models. We identified small molecule inhibitors specific to SCF-Skp2 activity using in silico screens targeted to the binding interface for p27. These compounds selectively inhibited Skp2-mediated p27 degradation by reducing p27 binding through key compound-receptor contacts. In cancer cells, the compounds induced p27 accumulation in a Skp2-dependent manner and promoted cell-type-specific blocks in the G1 or G2/M phases. Designing SCF-Skp2-specific inhibitors may be a novel strategy to treat cancers dependent on the Skp2-p27 axis.
| S-EPMC3530153 | biostudies-literature
Project description:Skp2 is a member of the F-box family of proteins that serve as substrate-specific adaptors in Skp1-CUL1-ROC1-F-box (SCF) E3 ubiquitin ligases. Skp2 (Fbxl1) directly binds to the tumor suppressor p27 in the context of the SCFSkp2 E3 ubiquitin ligase to ubiquitylate and target-phosphorylated p27 for proteasomal degradation. As p27 is a powerful suppressor of growth in a variety of cells, and as Skp2 is also overexpressed in many human cancers, Skp2 is considered an oncogene and an intriguing drug target. However, despite 20 years of investigation, a valid chemical inhibitor of Skp2-mediated degradation of p27 has not been identified. Recently, an increasing number of compounds designed to have this bioactivity have been reported. Here, we conduct a meta-analysis of the evidence regarding bioactivity, structure, and medicinal chemistry in order to evaluate and compare these Skp2 inhibitor compounds. Despite chemically diverse compounds with a wide array of Skp2-mediated p27 ubiquitylation inhibition properties reported by several independent groups, no current chemical probe formally qualifies as a validated pharmaceutical hit compound. This finding suggests that our knowledge of the structural biochemistry of the Skp2-p27 complex remains incomplete and highlights the need for novel modes of inquiry.
| S-EPMC6072517 | biostudies-literature
Project description:The expression level of microRNAs in FLT3-ITD+ AML is unknown. Using empty vector (EV) lentiviral CRISPR-Cas9 infected FLT3-ITD+ AML cell lines (MV4-11 cells), we performed next generation RNA sequencing on small RNAs to determine microRNA expression level in these cells. We found a variety of evolutionarily conserved and non-conserved microRNAs expressed in our cells of interest. Small RNAseq on EV lentiviral CRISPR-Cas9 infected MV4-11 cell lines was performed on triplicate cultures.
2016-07-01 | E-GEOD-71543 | biostudies-arrayexpress
Project description:Epigenomic profiling by ChIP-seq is a prevailing methodology used to investigate chromatin-based regulation in biological systems, such as human disease, yet the lack of an empirical methodology to normalize amongst experiments has limited the usefulness of this technique. Here we describe a “spike-in” normalization method that allows the quantitative comparison of histone modification status across cell populations using defined quantities of a reference epigenome. We demonstrate the utility of this method in measuring epigenomic changes following chemical perturbations and show how control normalization of ChIP-seq experiments enables discovery of disease-relevant changes in histone modification occupancy. ChIP-Seq of histone modifications H3K79me2 and H3K4me3 in human samples treated with EPZ-5676 with/without reference epigenome spike-in.
2014-10-30 | E-GEOD-60104 | biostudies-arrayexpress
Project description:BackgroundExcessive growth of keratinocytes is the critical event in the etiology of psoriasis. However, the underlying molecular mechanism of psoriatic keratinocyte hyperproliferation is still unclear.ObjectiveThis study aimed to figure out the potential contributory role of S-phase kinase-associated protein 2 (SKP2) in promoting the hyperproliferation of keratinocytes in psoriasis.MethodsWe analyzed microarray data (GSE41662) to investigate the gene expression of SKP2 in psoriatic lesion skins compared with their adjacent non-lesional skin. Then, we further confirmed the mRNA and protein expression of SKP2 in human psoriatic skin tissues, imiquimod (IMQ)-induced psoriatic mice back skins and tumor necrosis factor α (TNF-α), interleukin (IL)-17A and IL-6-stimulated keratinocytes by using real-time quantitative polymerase chain reaction and western blot (WB). Furthermore, we explored the potential pathogenic role and its underlying cellular mechanism of SKP2 in promoting keratinocytes hyperproliferation through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, cell cycle detection, 5-ethynyl-2'-deoxyuridine staining and WB. Finally, we determined whether inhibition of SKP2 can effectively alleviate the keratinocytes hyperproliferation in vivo.ResultsWe identified that SKP2 is aberrantly upregulated in the psoriatic lesion skin and cytokines-stimulated keratinocytes. Moreover, upregulated SKP2 augments cytokines-induced keratinocytes hyperproliferation. Mechanistically, enhanced SKP2 increased the S phase ratio through inhibiting Cyclin-Dependent Kinase Inhibitor p27 (P27 Kip1) expression. Correspondingly, suppression of SKP2 with SMIP004 can significantly ease the epidermis hyperplasia in vivo.ConclusionOur results suggest that elevated SKP2 can empower keratinocytes proliferation and psoriasis-like epidermis hyperplasia via downregulation of P27 Kip1. Therefore, targeting SKP2-P27 Kip1 axis might be a promising therapeutic strategy for the treatment of psoriasis in future.
| S-EPMC11439983 | biostudies-literature