MDM2 Controls the Timely Expression of Cyclin A to Regulate the Cell Cycle

Frum, Rebecca A.; Ramamoorthy, Mahesh; Mohanraj, Lathika; Deb, Sumitra

doi:10.1158/1541-7786.mcr-08-0334

Cited by 23 publications

(41 citation statements)

References 51 publications

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“…The lentiviral vectors to express shRNA against MDM2 (shMDM2-1 and -2), p53 (shp53), or luciferase (shLuc) were generated by transfecting the respective recombinant plasmid encoding shRNA into 293T cells (ATCC) by following the supplier's protocol as described previously. 29,30 For expression of shRNA, cells were infected with lentiviruses. Infected cells were incubated for 72 hours, after which cells were harvested for RNA preparation.…”

Section: Methodsmentioning

confidence: 99%

“…2), we investigated whether knockdown of endogenous MDM2 in lung cancer H460 or lung fibroblast WI38 cells could down-regulate expression of p100/NF-κB2 transcripts. H460 and WI38 cells, both of which harbor WT p53, 28 were infected with lentiviral vectors expressing shRNA against MDM2 (shMDM2-1 and shMDM-2) or a non-endogenous luciferase gene (shLuc) as described earlier, 29 and the levels of MDM2 and p100/ NF-κB2 transcripts were determined by QPCR. As shown in Fig.…”

Section: Reduction Of Endogenous Mdm2 Expression With Shrna Against Mmentioning

confidence: 99%

“…30 The control cells were infected with a non-endogenous luciferase gene (shLuc) as described earlier. 29 The cells were selected with appropriate antibiotics encoded by the viral vectors, and the levels of . p100/NF-κ B2 expression in human lung tumors with WT and mutant p53 (A) and correlation of MDM2 and p100/NF-κB2 expression in human lung tumor samples without p53 mutation (B).…”

Section: Reduction Of Endogenous Mdm2 Expression With Shrna Against Mmentioning

confidence: 99%

“…Cell growth assays were performed as described earlier with some modifications. 29 Cells were seeded at a density of 5 × 10 4 cells per 60-mm plate 16 hours after transfection of NF-κB2 or control siRNA. Triplicate sets of plates were harvested at 24-hour intervals and counted using a Coulter counter.…”

Section: Generation Of Cdna and Quantitative Pcr (Qpcr)mentioning

confidence: 99%

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Human Oncoprotein MDM2 Up-regulates Expression of NF- B2 Precursor p100 Conferring a Survival Advantage to Lung Cells

Vaughan

Mohanraj

Singh³

et al. 2011

Genes & Cancer

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The current model predicts that MDM2 is primarily overexpressed in cancers with wild-type (WT) p53 and contributes to oncogenesis by degrading p53. Following a correlated expression of MDM2 and NF-κB2 transcripts in human lung tumors, we have identified a novel transactivation function of MDM2. Here, we report that in human lung tumors, overexpression of MDM2 was found in approximately 30% of cases irrespective of their p53 status, and expression of MDM2 and NF-κB2 transcripts showed a highly significant statistical correlation in tumors with WT p53. We investigated the significance of this correlated expression in terms of mechanism and biological function. Increase in MDM2 expression from its own promoter in transgenic mice remarkably enhanced expression of NF-κB2 compared with its non-transgenic littermates. Knockdown or elimination of endogenous MDM2 expression in cultured non-transformed or lung tumor cells drastically reduced expression of NF-κB2 transcripts, suggesting a normal physiological role of MDM2 in regulating NF-κB2 transcription. MDM2 could up-regulate expression of NF-κB2 transcripts when its p53-interaction domain was blocked with Nutlin-3, indicating that the MDM2-p53 interaction is dispensable for up-regulation of NF-κB2 expression. Consistently, analysis of functional domains of MDM2 indicated that although the p53-interaction domain of MDM2 contributes to the up-regulation of the NFκB2 promoter, MDM2 does not require direct interactions with p53 for this function. Accordingly, MDM2 overexpression in non-transformed or lung cancer cells devoid of p53 also generated a significant increase in the expression of NF-κB2 transcript and its targets CXCL-1 and CXCL-10, whereas elimination of MDM2 expression had the opposite effects. MDM2-mediated increase in p100/NF-κB2 expression reduced cell death mediated by paclitaxel. Furthermore, knockdown of NF-κB2 expression retarded cell proliferation. Based on these data, we propose that MDM2-mediated NF-κB2 up-regulation is a combined effect of p53-dependent and independent mechanisms and that it confers a survival advantage to lung cancer cells.

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Section: Methodsmentioning

confidence: 99%

Section: Reduction Of Endogenous Mdm2 Expression With Shrna Against Mmentioning

confidence: 99%

Section: Reduction Of Endogenous Mdm2 Expression With Shrna Against Mmentioning

confidence: 99%

Section: Generation Of Cdna and Quantitative Pcr (Qpcr)mentioning

confidence: 99%

See 2 more Smart Citations

Human Oncoprotein MDM2 Up-regulates Expression of NF- B2 Precursor p100 Conferring a Survival Advantage to Lung Cells

Vaughan

Mohanraj

Singh³

et al. 2011

Genes & Cancer

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“…To determine how NVP-BEZ235 induces G 1 arrest in GSCs, we examined the expression of endogenous cyclins in SU-2 cells after 48 h of treatment with IR (8 Gy) and NVP-BEZ235 (10 nmol/L). Cyclin A is involved in meiotic progression and has markedly lower expression in cells arrested in the G 1 phase [33][34][35] . Cyclin D1 is a key regulator of the G 1 to S phase progression and is aberrantly expressed in numerous human cancers [36] .…”

Section: G 1 Phase Block Induced By Ir and Nvp-bez235mentioning

confidence: 99%

NVP-BEZ235, a novel dual PI3K/mTOR inhibitor, enhances the radiosensitivity of human glioma stem cells in vitro

et al. 2013

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Aim: NVP-BEZ235 is a novel dual PI3K/mTOR inhibitor and shows dramatic effects on gliomas. The aim of this study was to investigate the effects of NVP-BEZ235 on the radiosensitivity and autophagy of glioma stem cells (GSCs) in vitro. Methods: Human GSCs (SU-2) were tested. The cell viability and survival from ionizing radiation (IR) were evaluated using MTT and clonogenic survival assay, respectively. Immunofluorescence assays were used to identify the formation of autophagosomes. The apoptotic cells were quantified with annexin V-FITC/PI staining and flow cytometry, and observed using Hoechst 33258 staining and fluorescence microscope. Western blot analysis was used to analyze the expression levels of proteins. Cell cycle status was determined by measuring DNA content after staining with PI. DNA repair in the cells was assessed using a comet assay. Results: Treatment of SU-2 cells with NVP-BEZ235 (10-320 nmol/L) alone suppressed the cell growth in a concentration-dependent manner. A low concentration of NVP-BEZ235 (10 nmol/L) significantly increased the radiation sensitivity of SU-2 cells, which could be blocked by co-treatment with 3-MA (50 µmol/L). In NVP-BEZ235-treated SU-2 cells, more punctate patterns of microtubule-associated protein LC3 immunoreactivity was observed, and the level of membrane-bound LC3-II was significantly increased. A combination of IR with NVP-BEZ235 significantly increased the apoptosis of SU-2 cells, as shown in the increased levels of BID, Bax, and active caspase-3, and decreased level of Bcl-2. Furthermore, the combination of IR with NVP-BEZ235 led to G 1 cell cycle arrest. Moreover, NVP-BEZ235 significantly attenuated the repair of IR-induced DNA damage as reflected by the tail length of the comet. Conclusion: NVP-BEZ235 increases the radiosensitivity of GSCs in vitro by activating autophagy that is associated with synergistic increase of apoptosis and cell-cycle arrest and decrease of DNA repair capacity.

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Gain-of-function p53 activates multiple signaling pathways to induce oncogenicity in lung cancer cells

et al. 2017

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Gain‐of‐function (GOF) mutants of p53 upregulate genes implicated in cell proliferation and oncogenesis. Here, we report that GOF p53 induces tumorigenicity through simultaneous activation of key oncogenic pathways including those controlling putative tumor‐initiating cell functions. We determined that in cells expressing p53‐R273H, GOF p53 simultaneously upregulates genes from multiple signaling pathways by recognizing promoters containing distinct transcription factor (TF) binding sites. Our analytical data support a model in which GOF p53 complexes with two TFs on the promoter—a mediator protein, Med17, and a histone acetyl transferase, activating histone acetylation—and enhances gene expression to signal cell proliferation and oncogenesis. Thus, therapeutic inhibition of one GOF p53‐induced pathway would be insufficient to prevent tumor growth as the oncoprotein activates a multitude of parallel pathways. This discovery suggests enormous selection advantage for cancer cells with GOF p53 to induce oncogenic growth, highlighting the problems of cancer therapy.

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MDM2 Controls the Timely Expression of Cyclin A to Regulate the Cell Cycle

Cited by 23 publications

References 51 publications

Human Oncoprotein MDM2 Up-regulates Expression of NF- B2 Precursor p100 Conferring a Survival Advantage to Lung Cells

Human Oncoprotein MDM2 Up-regulates Expression of NF- B2 Precursor p100 Conferring a Survival Advantage to Lung Cells

NVP-BEZ235, a novel dual PI3K/mTOR inhibitor, enhances the radiosensitivity of human glioma stem cells in vitro

Gain-of-function p53 activates multiple signaling pathways to induce oncogenicity in lung cancer cells

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