nutlin-3a and Lung-Neoplasms

Actinomycin D and nutlin-3a (A + N) activate p53, partly through induction of phosphorylation on Ser392. The death of A549 cells induced by A + N morphologically resembles inflammation-inducing pyroptosis - cell destruction triggered by activated caspase-1. The treatment with A + N (or camptothecin) strongly upregulated caspase-1 and its two activators: IFI16 and NLRP1, however, caspase-1 activation was not detected. A549 cells may have been primed for pyroptosis, with the absence of a crucial trigger. The investigation of additional innate immunity elements revealed that A + N (or camptothecin) stimulated the expression of NLRX1, STING (stimulator of interferon genes) and two antiviral proteins, IFIT1 and IFIT3. IFI16 and caspase-1 are coded by p53-regulated genes which led us to investigate regulation of NLRP1, NLRX1, STING, IFIT1 and IFIT3 in p53-dependent mode. The upregulation of NLRP1, NLRX1 and STING was attenuated in p53 knockdown cells. The upsurge of the examined genes, and activation of p53, was inhibited by C16, an inhibitor of PKR kinase. PKR was tested due to its ability to phosphorylate p53 on Ser392. Surprisingly, C16 was active even in PKR knockdown cells. The ability of C16 to prevent activation of p53 and expression of innate immunity genes may be the source of its strong anti-inflammatory action. Moreover, cells exposed to A + N can influence neighboring cells in paracrine fashion, for instance, they shed ectodomain of COL17A1 protein and induce, in p53-dependent mode, the expression of gene for interleukin-7. Further, the activation of p53 also spurred the expression of SOCS1, an inhibitor of interferon triggered STAT1-dependent signaling. We conclude that, stimulation of p53 primes cells for the production of interferons (through upregulation of STING), and may activate negative-feedback within this signaling system by enhancing the production of SOCS1.

Topics: A549 Cells; Antibiotics, Antineoplastic; Dactinomycin; Humans; Imidazoles; Immunity, Innate; Lung Neoplasms; Piperazines; Pyroptosis; Transcriptional Activation; Tumor Suppressor Protein p53

GPRC5A, a retinoic acid induced gene, is preferentially expressed in lung tissue. Gprc5a gene deletion leads to spontaneous lung tumor development. However, the mechanism of Gprc5a-mediated lung tumor suppression is not fully understood. Here we showed that MDM2, a p53-negative regulator, was dysregulated in Gprc5a-knockout (ko) mouse tracheal epithelial cells (KO-MTEC) compared to wild type ones. Targeting MDM2 in 1601-a Gprc5a-ko mouse derived lung tumor cell line-and A549-human lung cancer cells, by MDM2 inhibitor Nutlin-3a or small hairpin RNA (sh-RNA)-restored p53 signaling pathway, reduced cancer stem cell markers, and inhibited tumorigenicity. This suggests that dysregulated MDM2 pathway is essential for the oncogenic activities of these cells. MDM2 was found to be stabilized mainly by activated EGFR signaling as targeting EGFR by Erlotinib or sh-RNA repressed MDM2 in a transcription-independent manner. Importantly, overexpression of MDM2 and reduced GPRC5A expression at both protein and mRNA levels were frequently found in clinical human lung cancer tissues. Taken together, GPRC5A deficiency contributes to dysregulated MDM2 via activated EGFR signaling, which promotes lung tumor development.

Topics: A549 Cells; Animals; Cell Line, Tumor; ErbB Receptors; Gene Expression Regulation, Neoplastic; Humans; Imidazoles; Lung Neoplasms; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Nude; Piperazines; Proto-Oncogene Proteins c-mdm2; Receptors, G-Protein-Coupled; RNA Interference; Signal Transduction; Xenograft Model Antitumor Assays

Activated p53 can promote apoptosis or cell cycle arrest. Differences in energy metabolism can influence cell fate in response to activated p53. Nutlin-3a is a preclinical drug and small molecule activator of p53. Alpha-ketoglutarate (αKG) levels were reduced in cells sensitive to Nutlin-3a-induced apoptosis and increased in cells resistant to this apoptosis. Add-back of a cell-permeable αKG analog (DMKG) rescued cells from apoptosis in response to Nutlin-3a. OGDH is a component of the αKGDH complex that converts αKG to succinate. OGDH knockdown increased endogenous αKG levels and also rescued cells from Nutlin-3a-induced apoptosis. We previously showed reduced autophagy and ATG gene expression contributes to Nutlin-3a-induced apoptosis. DMKG and OGDH knockdown restored autophagy and ATG gene expression in Nutlin-3a-treated cells. These studies indicate αKG levels, regulated by p53 and OGDH, determine autophagy and apoptosis in response to Nutlin-3a.

Topics: A549 Cells; Apoptosis; Autophagy; Bone Neoplasms; Cell Line, Tumor; Gene Knockdown Techniques; Glycolysis; Humans; Imidazoles; Ketoglutarate Dehydrogenase Complex; Ketoglutaric Acids; Lung Neoplasms; Mechanistic Target of Rapamycin Complex 1; Neoplasms; Osteosarcoma; Piperazines; Tumor Suppressor Protein p53

The aim of this study was to investigate the potential biological activities of nutlin-3 in the regulation of growth and proliferation of non-small cell lung cancer (NSCLC) stem cells (CSCs), which may help in sensitizing to axitinib-induced apoptosis. Nutlin-3 induction of p53 expression was used to test its role in controlling the cell division pattern and apoptosis of NSCLC cells. A549 cells and H460 cells were pretreated with nutlin-3 and then treated with either an Akt1 activator or shRNA-GSK3β, to investigate the potential role of p53 sensitization in the biological effects of axitinib. We also determined the expression levels of GSK3β and p-Akt1 in patients with NSCLC and determined their potential association with survival data using Kaplan-Meier plots and CBIOTAL. Increased p53 expression stimulated the induction of apoptosis by axitinib and promoted asymmetric cell division (ACD) of NSCLC CSCs. The repression of Akt phosphorylation induced by nutlin-3 promoted the ACD of lung CSCs, decreasing the proportion of the stem cell population. In addition to the induction of apoptosis by axitinib through inhibition of Wnt signaling, nutlin-3 treatment further enhanced axitinib-induced apoptosis by inhibiting Akt1/GSK3β/Wnt signaling. The low expression of GSK3β and increased expression of p-Akt in patients with NSCLC were closely associated with the development of NSCLC. TP53 stimulates the induction of apoptosis in NSCLC by axitinib and the ACD of lung CSCs through its regulatory effects on the p53/Akt/GSK3β pathways.

Topics: A549 Cells; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Axitinib; Carcinoma, Non-Small-Cell Lung; Cell Proliferation; Drug Synergism; Humans; Imidazoles; Immunohistochemistry; Lung Neoplasms; Piperazines; Proto-Oncogene Proteins c-akt; Wnt Signaling Pathway

As an anticancer therapeutic, Interferon-alpha (IFNα) is used to treat a number of malignancies. However, the application of IFNα is restricted mostly due to its high toxicity. Therefore, novel combination therapeutic regimens are required to decrease the toxicity of IFNα and enhance its efficacy. Here we show that the treatment of p53-deficient human non-small lung carcinoma H1299 cells with IFNα in combination with an inhibitor of MDM2, Nutlin-3a, synergistically affects the proliferation of cancer cells. Importantly, Nutlin-3a was able to reduce the effective dose of IFNα about 3.4 times. Strikingly, this phenomenon is p53-independent, because H1299 cells lack p53, but is highly dependent on MDM2 because its ablation makes tumor cells completely insensitive to IFNα alone or in combination with Nutlin-3a. On the contrary, overexpression of MDM2 makes H1299 cells more susceptible to both IFNα and IFNα/Nutlin-3a treatments. Mechanistically, treatment with combination of IFNα and Nutlin-3a attenuates cyclin D1/CDK4 on the protein level and hence blocks cell cycle progression. This mechanism may be responsible, at least in part, for the anti-proliferative effects on H1299 cells observed. Our data suggest that the expression of MDM2 confers sensitivity of cancer cells to IFNα/Nutlin-3a treatment. Moreover, our data also confirm positive effect of Nutlin even on p53-deficient neoplasms.

Topics: Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Dose-Response Relationship, Drug; Drug Synergism; Humans; Imidazoles; Interferon-alpha; Lung Neoplasms; Piperazines; Proto-Oncogene Proteins c-mdm2; Treatment Outcome; Tumor Suppressor Protein p53

Small molecule Nutlin-3 reactivates p53 in cancer cells by interacting with the complex between p53 and its repressor Mdm-2 and causing an increase in cancer cell apoptosis. Therefore, Nutlin-3 has potent anticancer properties. Clinical and experimental studies of Nutlin-3 showed that some cancer cells may lose sensitivity to this compound. Here we analyze possible mechanisms for insensitivity of cancer cells to Nutlin-3.. We applied upstream analysis approach implemented in geneXplain platform ( genexplain.com ) using TRANSFAC® database of transcription factors and their binding sites in genome and using TRANSPATH® database of signal transduction network with associated software such as Match™ and Composite Module Analyst (CMA).. Using genome-wide gene expression profiling we compared several lung cancer cell lines and showed that expression programs executed in Nutlin-3 insensitive cell lines significantly differ from that of Nutlin-3 sensitive cell lines. Using artificial intelligence approach embed in CMA software, we identified a set of transcription factors cooperatively binding to the promoters of genes up-regulated in the Nutlin-3 insensitive cell lines. Graph analysis of signal transduction network upstream of these transcription factors allowed us to identify potential master-regulators responsible for maintaining such low sensitivity to Nutlin-3 with the most promising candidate mTOR, which acts in the context of activated PI3K pathway. These finding were validated experimentally using an array of chemical inhibitors.. We showed that the Nutlin-3 insensitive cell lines are actually highly sensitive to the dual PI3K/mTOR inhibitor NVP-BEZ235, while no responding to either PI3K -specific LY294002 nor Bcl-XL specific 2,3-DCPE compounds.

Topics: Apoptosis; Cell Proliferation; Drug Resistance, Neoplasm; Humans; Imidazoles; Lung Neoplasms; Phosphatidylinositol 3-Kinases; Piperazines; Protein Kinase Inhibitors; Signal Transduction; TOR Serine-Threonine Kinases; Tumor Cells, Cultured; Tumor Suppressor Protein p53

MDM2 inhibitors are promising anticancer agents that induce cell cycle arrest and tumor cells death via p53 reactivation. We examined the influence of Mycoplasma hyorhinis infection on sensitivity of human lung carcinoma cells NCI-H292 to MDM2 inhibitor Nutlin-3. In order to unveil possible mechanisms underlying the revealed effect, we investigated gene expression changes and signal transduction networks activated in NCI-H292 cells in response to mycoplasma infection.. Sensitivity of NCI-Н292 cells to Nutlin-3 was estimated by resazurin-based cell viability assay. Genome-wide transcriptional profiles of NCI-H292 and NCI-Н292. NCI-Н292. Our results provide evidence that mycoplasma infection is an important factor modulating the effect of MDM2 inhibitors on cancer cells and is able to induce EMT-related changes.

Topics: Adult; Aged; Aged, 80 and over; Carcinoma, Mucoepidermoid; Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; Drug Resistance, Neoplasm; Female; Gene Expression; Humans; Imidazoles; Lung Neoplasms; Male; Middle Aged; Mycoplasma hyorhinis; Mycoplasma Infections; Piperazines; Signal Transduction; Transcriptome; Young Adult

In addition to the involvement in white matter lesion, tripartite-motif protein family member 65 (TRIM65) has also been implicated in tumorigenesis as a potential oncogene. However, the underlining mechanisms of TRIM65 functions and its clinical implication still remain to be further elucidated. In the present study, we found that TRIM65 binds to the N-terminus of p53 tumor suppressor and thus competes with MDM2 for p53 binding. Intriguingly, analysis of the Cancer Genome Atlas (TCGA) gene alteration database revealed that elevated expression of TRIM65 is mutually exclusive to MDM2 up-regulation in human lung adenocarcinoma patients, indicating potential compensatory effect of one over the other. Indeed, overexpression of TRIM65 renders lung cancer cell line resistance to Nutlin-3a, an effective MDM2 inhibitor, as determined by p53 activation and cell proliferation assays. Furthermore, depletion of TRIM65 using siRNA in combination with Nutlin-3a treatment demonstrates enhanced anti-tumor effects on lung cancer cell line. Collectively, our findings provide the rationale for developing strategies to target TRIM65 for lung cancer intervention, potentially in combination with MDM2 inhibition.

Topics: Adenocarcinoma of Lung; Binding, Competitive; Cell Line, Tumor; Cell Survival; Drug Resistance, Neoplasm; Drug Synergism; Humans; Imidazoles; Lung Neoplasms; Piperazines; Protein Binding; Proto-Oncogene Proteins c-mdm2; Tripartite Motif Proteins; Tumor Suppressor Protein p53; Ubiquitin-Protein Ligases

Mesothelioma is resistant to conventional treatments and is often defective in p53 pathways. We then examined anti-tumor effects of metformin, an agent for type 2 diabetes, and combinatory effects of metformin and nutlin-3a, an inhibitor for ubiquitin-mediated p53 degradation, on human mesothelioma.. We examined the effects with a colorimetric assay and cell cycle analyses, and investigated molecular events in cells treated with metformin and/or nutlin-3a with Western blot analyses. An involvement of p53 was tested with siRNA for p53.. Metformin suppressed cell growth of 9 kinds of mesothelioma including immortalized cells of mesothelium origin irrespective of the p53 functional status, whereas susceptibility to nutlin-3a was partly dependent on the p53 genotype. We investigated combinatory effects of metformin and nutlin-3a on, nutlin-3a sensitive MSTO-211H and NCI-H28 cells and insensitive EHMES-10 cells, all of which had the wild-type p53 gene. Knockdown of p53 expression with the siRNA demonstrated that susceptibility of MSTO-211H and NCI-H28 cells to nutlin-3a was p53-dependent, whereas that of EHMES-10 cells was not. Nevertheless, all the cells treated with both agents produced additive or synergistic growth inhibitory effects. Cell cycle analyses also showed that the combination increased sub-G1 fractions greater than metformin or nutlin-3a alone in MSTO-211H and EHMES-10 cells. Western blot analyses showed that metformin inhibited downstream pathways of the mammalian target of rapamycin (mTOR) but did not activate the p53 pathways, whereas nutlin-3a phosphorylated p53 and suppressed mTOR pathways. Cleaved caspase-3 and conversion of LC3A/B were also detected but it was dependent on cells and treatments. The combination of both agents in MSTO-211H cells rather suppressed the p53 pathways that were activated by nutrin-3a treatments, whereas the combination rather augmented the p53 actions in NCI-H28 and EHMES-10 cells.. These data collectively indicated a possible interactions between mTOR and p53 pathways, and the combinatory effects were attributable to differential mechanisms induced by a cross-talk between the pathways.

Topics: Antineoplastic Agents; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Humans; Imidazoles; Lung Neoplasms; Mesothelioma; Mesothelioma, Malignant; Metformin; Piperazines; Signal Transduction; TOR Serine-Threonine Kinases; Tumor Suppressor Protein p53

Malignant Pleural Mesothelioma (MPM) is a chemoresistant tumor characterized by low rate of p53 mutation and upregulation of Murine Double Minute 2 (MDM2), suggesting that it may be effectively targeted using MDM2 inhibitors. In the present study, we investigated the anticancer activity of the MDM2 inhibitors Nutlin 3a (in vitro) and RG7112 (in vivo), as single agents or in combination with rhTRAIL.In vitro studies were performed using MPM cell lines derived from epithelioid (ZL55, M14K), biphasic (MSTO211H) and sarcomatoid (ZL34) MPMs. In vivo studies were conducted on a sarcomatoid MPM mouse model.In all the cell lines tested (with the exception of ZL55, which carries a biallelic loss-of-function mutation of p53), Nutlin 3a enhanced p21, MDM2 and DR5 expression, and decreased survivin expression. These changes were associated to cell cycle arrest but not to a significant induction of apoptosis. A synergistic pro-apoptotic effect was obtained through the association of rhTRAIL in all the cell lines harboring functional p53. This synergistic interaction of MDM2 inhibitor and TRAIL agonist was confirmed using a mouse preclinical model. Our results suggest that the combined targeting of MDM2 and TRAIL might provide a novel therapeutic option for treatment of MPM patients, particularly in the case of sarcomatoid MPM with MDM2 overexpression and functional inactivation of wild-type p53.

Topics: Animals; Antineoplastic Agents; Apoptosis; Biomarkers, Tumor; Cell Cycle Checkpoints; Cell Line, Tumor; Drug Synergism; Humans; Imidazoles; Lung Neoplasms; Mesothelioma; Mesothelioma, Malignant; Mice; Mutation; Piperazines; Pleural Neoplasms; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-mdm2; TNF-Related Apoptosis-Inducing Ligand

Lung adenocarcinoma accounts for ∼40% of lung cancers, the leading cause of cancer-related death worldwide, and current therapies provide only limited survival benefit. Approximately half of lung adenocarcinomas harbor mutations in

Topics: Adenocarcinoma; Adenocarcinoma of Lung; Animals; Antineoplastic Agents; Cell Cycle Checkpoints; Cell Death; Cell Line, Tumor; Disease Models, Animal; Drug Resistance, Neoplasm; Gene Expression Regulation, Neoplastic; Genotype; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Imidazoles; Lung Neoplasms; Mice; Molecular Targeted Therapy; Mutation; Piperazines; Simvastatin; Tumor Suppressor Protein p53

The p53/MDM2 interaction has been a well-studied target for new drug design leading to the development of the small molecule inhibitor Nutlin-3. Our objectives were to combine Nutlin-3 with cisplatin (CDDP), a well-known activator of the p53 pathway, in a series of non-small cell lung cancer cell lines in order to increase the cytotoxic response to CDDP. We report that sequential treatment (CDDP followed by Nutlin-3), but not simultaneous treatment, resulted in strong synergism. Combination treatment induced p53's transcriptional activity, resulting in increased mRNA and protein levels of MDM2, p21, PUMA and BAX. In addition we report the induction of a strong p53 dependent apoptotic response and induction of G2/M cell cycle arrest. The strongest synergistic effect was observed at low doses of both CDDP and Nutlin-3, which could result in fewer (off-target) side effects while maintaining a strong cytotoxic effect. Our results indicate a promising preclinical potential, emphasizing the importance of the applied treatment scheme and the presence of wild type p53 for the combination of CDDP and Nutlin-3.

Topics: Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; Cisplatin; Drug Administration Schedule; Drug Synergism; Humans; Imidazoles; Lung Neoplasms; Piperazines; Proto-Oncogene Proteins c-mdm2; RNA, Messenger; Transcriptional Activation; Tumor Suppressor Protein p53

Triple-negative breast cancers (TNBC) are typically resistant to treatment, and strategies that build upon frontline therapy are needed. Targeting the murine double minute 2 (Mdm2) protein is an attractive approach, as Mdm2 levels are elevated in many therapy-refractive breast cancers. The Mdm2 protein-protein interaction inhibitor Nutlin-3a blocks the binding of Mdm2 to key signaling molecules such as p53 and p73α and can result in activation of cell death signaling pathways. In the present study, the therapeutic potential of carboplatin and Nutlin-3a to treat TNBC was investigated, as carboplatin is under evaluation in clinical trials for TNBC. In mutant p53 TMD231 TNBC cells, carboplatin and Nutlin-3a led to increased Mdm2 and was strongly synergistic in promoting cell death in vitro. Furthermore, sensitivity of TNBC cells to combination treatment was dependent on p73α. Following combination treatment, γH2AX increased and Mdm2 localized to a larger degree to chromatin compared with single-agent treatment, consistent with previous observations that Mdm2 binds to the Mre11/Rad50/Nbs1 complex associated with DNA and inhibits the DNA damage response. In vivo efficacy studies were conducted in the TMD231 orthotopic mammary fat pad model in NOD.Cg-Prkdc(scid)Il2rg(tm1Wjl)/SzJ (NSG) mice. Using an intermittent dosing schedule of combined carboplatin and Nutlin-3a, there was a significant reduction in primary tumor growth and lung metastases compared with vehicle and single-agent treatments. In addition, there was minimal toxicity to the bone marrow and normal tissues. These studies demonstrate that Mdm2 holds promise as a therapeutic target in combination with conventional therapy and may lead to new clinical therapies for TNBC.

Topics: Animals; Carboplatin; Cell Death; Clinical Trials as Topic; Disease Models, Animal; DNA Damage; DNA-Binding Proteins; Histones; Humans; Imidazoles; Lung Neoplasms; MCF-7 Cells; Mice; Neoplasm Metastasis; Nuclear Proteins; Piperazines; Proto-Oncogene Proteins c-mdm2; Triple Negative Breast Neoplasms; Tumor Protein p73; Tumor Suppressor Protein p53; Tumor Suppressor Proteins

Introducing an aryl moiety to our previous pyrrolidone scaffold by molecule fusing strategy afforded two sets of isopropylether-pyrrolidone and α-phenylethylamine-pyrrolidone derivatives. Two novel compounds 8b and 8g of the latter serial showed potent p53-MDM2 inhibitory activities with Ki values of 90nM which were three-time higher than that of the parent compound. We also confirmed compound 8b can activate p53 proteins in lung cancer A549 cells. The results offered us valuable information for further lead optimization.

Topics: Antineoplastic Agents; Cell Line, Tumor; Drug Design; Humans; Imidazolines; Lung Neoplasms; Proto-Oncogene Proteins c-mdm2; Pyrrolidinones; Tumor Suppressor Protein p53

Malignant mesothelioma, a very aggressive tumor associated to asbestos exposure, is expected to increase in incidence, and unfortunately, no curative modality exists. Reactivation of p53 is a new attractive antitumoral strategy. p53 is rarely mutated in mesothelioma, but it is inactivated in most tumors by the lack of p14(ARF). Here, we evaluated the feasibility of this approach in pleural mesothelioma by testing RITA and nutlin-3, two molecules able to restore p53 function through a different mechanism, on a panel of mesothelioma cell lines representing the epithelioid (NCI-H28, NCI-H2452, IST-MES 2), biphasic (MSTO-211H), and sarcomatoid (NCI-H2052) histotypes compared with the normal mesothelial HMC-hTERT. RITA triggered robust caspase-dependent apoptosis specifically in epithelioid and biphasic mesothelioma cell lines, both through wild-type and mutant p53, concomitant to p21 downregulation. Conversely, nutlin-3 induced a p21-dependent growth arrest, rather than apoptosis, and was slightly toxic on HMC-hTERT.   Interestingly, we identified a previously undetected point mutation of p53 (p.Arg249Ser) in IST-MES 2, and showed that RITA is also able to reactivate this p53 mutant protein and its apoptotic function. RITA reduced tumor growth in a MSTO-211H-derived xenograft model of mesothelioma and synergized with cisplatin, which is the mainstay of treatment for this tumor. Our data indicate that reactivation of p53 and concomitant p21 downregulation effectively induce cell death in mesothelioma, a tumor characterized by a high intrinsic resistance to apoptosis. Altogether, our findings provide the preclinical framework supporting the use of p53-reactivating agents alone, or in combination regimens, to improve the outcome of patients with mesothelioma.

Topics: Antineoplastic Agents; Apoptosis; Cell Cycle; Cell Line, Tumor; Cell Survival; Cisplatin; Drug Synergism; Furans; Heterografts; Humans; Imidazoles; Lung Neoplasms; Mesothelioma; Mesothelioma, Malignant; Mutation; Piperazines; Pleural Neoplasms; rho GTP-Binding Proteins; Tumor Suppressor Protein p53

Arsenic trioxide has been demonstrated as an effective anti-cancer drug against leukemia and solid tumors both in vitro and in vivo. However, recent phase II trials demonstrated that single agent arsenic trioxide was poorly effective against hepatocellular carcinoma (HCC), which might be due to drug resistance.. Mutation detection of p53 gene in arsenic trioxide resistant HCC cell lines was performed. The therapeutic effects of arsenic trioxide and Nutlin-3 on HCC were evaluated both in vitro and in vivo. A series of experiments including MTT, apoptosis assays, co-Immunoprecipitation, siRNA transfection, lentiviral infection, cell migration, invasion, and epithelial-mesenchy-mal transition (EMT) assays were performed to investigate the underlying mechanisms.. The acquisition of p53 mutation contributed to arsenic trioxide resistance and enhanced metastatic potential of HCC cells. Mutant p53 (Mutp53) silence could re-sensitize HCC resistant cells to arsenic trioxide and inhibit the metastatic activities, while mutp53 overexpression showed the opposite effects. Neither arsenic trioxide nor Nutlin-3 could exhibit obvious effects against arsenic trioxide resistant HCC cells, while combination of them showed significant effects. Nutlin-3 can not only increase the intracellular arsenicals through inhibition of p-gp but also promote the p73 activation and mutp53 degradation mediated by arsenic trioxide. In vivo experiments indicated that Nutlin-3 can potentiate the antitumor activities of arsenic trioxide in an orthotopic hepatic tumor model and inhibit the metastasis to lung.. Acquisitions of p53 mutations contributed to the resistance of HCC to arsenic trioxide. Nutlin-3 could overcome arsenic trioxide resistance and inhibit tumor metastasis through p73 activation and promoting mutant p53 degradation mediated by arsenic trioxide.

Topics: Animals; Antineoplastic Agents; Arsenic Trioxide; Arsenicals; Carcinoma, Hepatocellular; Cell Line, Tumor; DNA-Binding Proteins; Drug Resistance, Neoplasm; Drug Synergism; Epithelial-Mesenchymal Transition; Gene Expression Regulation, Neoplastic; Humans; Imidazoles; Liver Neoplasms; Lung Neoplasms; Mice; Mice, Nude; Mutation; Neoplasm Transplantation; Nuclear Proteins; Oxides; Piperazines; Signal Transduction; Tumor Protein p73; Tumor Suppressor Protein p53; Tumor Suppressor Proteins

Radiotherapy is routinely used for the treatment of lung cancer. However, the mechanisms underlying ionizing radiation (IR)-induced senescence and its role in lung cancer treatment are poorly understood. Here, we show that IR suppresses the proliferation of human non-small cell lung cancer (NSCLC) cells via an apoptosis-independent mechanism. Further investigations reveal that the anticancer effect of irradiation correlates well with IR-induced premature senescence, as evidenced by increased senescence-associated β-glactosidase (SA-β-gal) staining, decreased BrdU incorporation and elevated expression of p16(INK4a) (p16) in irradiated NSCLC cells. Mechanistic studies indicate that the induction of senescence is associated with activation of the p53-p21 pathway, and that inhibition of p53 transcriptional activity by PFT-α attenuates IR-induced tumor cell killing and senescence. Gain-of-function assays demonstrate that restoration of p53 expression sensitizes H1299 cells to irradiation, whereas knockdown of p53 expression by siRNA inhibits IR-induced senescence in H460 cells. Furthermore, treatment with Nutlin-3a, a small molecule inhibitor of MDM2, enhances IR-induced tumor cell killing and senescence by stabilizing the activation of the p53-p21 signaling pathway. Taken together, these findings demonstrate for the first time that pharmacological activation of p53 by Nutlin-3a can sensitize lung cancer cells to radiation therapy via promoting IR-induced premature senescence.

Topics: Apoptosis; Cell Line, Tumor; Cell Proliferation; Cellular Senescence; Cyclin-Dependent Kinase Inhibitor p16; Cyclin-Dependent Kinase Inhibitor p21; Humans; Imidazoles; Lung Neoplasms; Piperazines; Proto-Oncogene Proteins c-mdm2; Radiation-Sensitizing Agents; Radiation, Ionizing; Signal Transduction; Tumor Suppressor Protein p53

Overexpression of DNA 5'-cytosine-methyltransferase 3A (DNMT3A), which silences genes including tumor suppressor genes (TSG), is involved in many cancers. Therefore, we examined whether the transcriptional deregulation of RB/MDM2 pathway was responsible for DNMT3A overexpression and analyzed the therapeutic potential of MDM2 antagonist for reversing aberrant DNA methylation status in lung cancer.. The regulation of DNMT3A expression and TSG methylation status by RB/MDM2 was assessed in cancer cell lines and patients. The effects of Nutlin-3, an MDM2 antagonist, on tumor growth in relation to DNMT3A expression and TSG methylation status were examined by xenograft model.. We found that RB suppressed DNMT3A promoter activity and mRNA/protein expression through binding with E2F1 protein to the DNMT3A promoter, leading to the decrease of methylation level globally and TSG specifically. In addition, MDM2 dramatically induced DNMT3A expression by negative control over RB. In clinical study, MDM2 overexpression inversely correlated with RB expression, while positively associating with overexpression of DNMT3A in samples from patients with lung cancer. Patients with high MDM2 and low RB expression showed DNMT3A overexpression with promoter hypermethylation in TSGs. Treatment with Nutlin-3, an MDM2 antagonist, significantly suppressed tumor growth and reduced DNA methylation level of TSGs through downregulation of DNMT3A expression in xenograft studies.. This study provides the first cell, animal, and clinical evidence that DNMT3A is transcriptionally repressed, in part, by RB/E2F pathway and that the repression could be attenuated by MDM2 overexpression. MDM2 is a potent target for anticancer therapy to reverse aberrant epigenetic status in cancers.

Topics: Animals; Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; Chromatin; DNA (Cytosine-5-)-Methyltransferases; DNA Methylation; DNA Methyltransferase 3A; E2F1 Transcription Factor; Female; Gene Expression; Gene Expression Regulation, Neoplastic; Genes, Retinoblastoma; Humans; Imidazoles; Lung Neoplasms; Mice; Mice, Inbred BALB C; Mice, Nude; Piperazines; Promoter Regions, Genetic; Protein Binding; Proto-Oncogene Proteins c-mdm2; Signal Transduction; Transcription, Genetic

Mutations within the tumor suppressor TP53 gene are one of the most common genetic alterations present at high frequency in human tumors and have been shown to be associated with resistance to radio-chemotherapy. The lack of the wild type TP53 gene in cancer cells could be exploited for therapeutic advantage using a sequence of two antagonistic drugs. The aim of this study was to selectively kill p53 deficient cells (FaDu and H1299) by taxol and to protect p53 wild type cells (A549) by the prior administration of nutlin-3 in comparison to certain known anticancer drugs (5-fluorouracil, camptothecin, roscovitine).. Cytotoxic and cytostatic properties of 5-fluorouracil, camptothecin, roscovitine and nutlin-3 administrating alone or in combination with taxol were investigated in vitro by flow cytometry.. It was found that nutlin-3 induced growth arrest and protected A549 cells from taxol. FaDu and H1299 cells responded to the same treatments with mitotic arrest and massive apoptosis. Other compounds (5-fluorouracil, camptothecin and roscovitine) revealed weaker selectivity and elevated toxicity in comparison to nutlin-3.. We propose a therapeutic strategy protecting normal cells from taxol while increasing apoptosis selectively in p53-deficient cells using nutlin-3.

Topics: Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Camptothecin; Cell Line, Tumor; Drug Screening Assays, Antitumor; Flow Cytometry; Fluorouracil; Gene Expression Regulation, Neoplastic; Humans; Imidazoles; Lung Neoplasms; Models, Genetic; Mutation; Piperazines; Purines; Roscovitine; Tumor Suppressor Protein p53

Nutlins were identified as the first potent and specific small molecule Mdm2 antagonists that inhibit the p53-Mdm2 interaction. We show in this study that Nutlin-3 can downregulate TNFalpha induced activation of the NFkappaB reporter in lung cancer cells. Activation of p53 dependent transcription is not compromised when Nutlin-3 is combined with TNFalpha. Instead, this combination treatment decreases cell viability in a p53 dependent manner. We show that Nutlin-3 strikingly inhibits the protein expression of NFkappaB target genes ICAM-1 and MCP-1 while other targets like Bcl-xL and FLIP are not affected, thereby suggesting that the inhibition is promoter specific. This inhibition of ICAM-1 and MCP-1 by Nutlin-3 is again dependent on the p53 status in cells. Furthermore, we show that Nutlin-3 strongly inhibits protein expression of ICAM-1 and MCP-1 induced by IL1, another NFkappaB activating stimuli. Nutlin-3 does not inhibit Akt phosphorylation, IkappaB alpha phosphorylation, IkappaB alpha degradation, p65 modification or p65 DNA binding in the cell lines tested. This study suggests the potential of Nutlin-3 as a bitargeted anti-cancer drug by simultaneously causing p53 activation and NFkappaB suppression. It also suggests that Nutlin-3 could be evaluated for treatment of lung cancer as a single agent or in combination therapy by targeting its effect on ICAM-1 and MCP-1 which are known to be critical for cancer cell invasion, thereby downregulating tumor formation and metastasis. This study also suggests biomarkers of response for evaluation of Nutlin-3 in the clinic.

Topics: Animals; Cell Line, Tumor; Cell Survival; Chemokine CCL2; DNA; Dose-Response Relationship, Drug; Drug Synergism; Electrophoretic Mobility Shift Assay; Genes, Reporter; Humans; I-kappa B Proteins; Imidazoles; Intercellular Adhesion Molecule-1; Interleukin-1; Lung Neoplasms; Mice; NF-kappa B; NF-KappaB Inhibitor alpha; Phosphorylation; Piperazines; Protein Binding; Protein Processing, Post-Translational; Proto-Oncogene Proteins c-akt; Time Factors; Transcription Factor RelA; Tumor Necrosis Factor-alpha; Tumor Suppressor Protein p53

p53 plays a critical role in cell cycle arrest and induction of apoptosis. Certain malignancies carry wild-type p53, which is frequently down-regulated by murine double minute 2 (MDM2) overexpression. Availability of a small-molecule inhibitor against MDM2, nutlin, has made it feasible to evaluate the anti-MDM2-based therapeutic strategies. The rationale for the current study is that functional p53 has been linked with improved responses to radiation treatment. Hence, this study evaluates the use of nutlin, a small-molecule inhibitor that blocks the interaction of p53 and MDM2, in sensitizing cancer cells to radiation. Expression of MDM2, p53, and p21 in both p53 wild-type and p53-defective lung cancer cell lines was examined. Clonogenic and 7-amino-actinomycin D studies were used to determine possible mechanisms of cell death. The combined effect of MDM2 inhibition and radiation on cell cycle was also studied. We found that radiosensitization by nutlin occurs in lung cancer cells with wild-type p53. There were increased apoptosis and cell cycle arrest following administration of nutlin and radiation. Furthermore, the combination of nutlin and radiation decreased the ability of endothelial cells to form vasculature, as shown by Matrigel assays. Our data suggest that nutlin is an effective radiosensitizer of p53 wild-type cells. The radiosensitizing effect seems to be at least partially due to induction of apoptosis and cell cycle arrest. In addition, nutlin may be an effective radiosensitizer of tumor vasculature.

Topics: Cell Cycle; Endothelium, Vascular; Humans; Imidazoles; Lung Neoplasms; Piperazines; Proto-Oncogene Proteins c-mdm2; Radiation Tolerance; Radiation-Sensitizing Agents; Stereoisomerism; Tumor Cells, Cultured; Tumor Suppressor Protein p53

The hdm-2 oncogene is overexpressed in several types of malignancies including osteosarcomas, soft tissue sarcomas and gliomas and hdm-2 has been associated with accelerated tumor formation in both hereditary and sporadic cancers. Among the other key binding partners, hdm-2 forms a complex with the tumor suppressor p53, resulting in a rapid proteasome-mediated degradation of the p53 protein. This positions the hdm-2-p53 complex as an attractive target for the development of anticancer therapy and recently the first small molecule hdm-2 antagonist has been reported. Development of hdm-2 antagonists is currently focused on malignancies containing a wild-type p53 genotype, which is the case in approximately half of human cancer indications. However, hdm-2 has also been implicated in oncogenesis in the absence of p53. We therefore studied the effect of hdm-2 antagonists in p53-deficient human H1299 lung carcinoma cells. The hdm-2 antagonistic peptide caused G1 cell cycle arrest, inhibited colony growth and induced expression of G1 checkpoint regulatory proteins, such as p21(waf1,cip1). These data demonstrate that hdm-2 regulates the G1 cell cycle checkpoint in a p53-independent manner, suggesting that hdm-2 antagonists represent a novel class of anticancer therapeutics with broad applicability towards tumors with different p53 genetic backgrounds.

Topics: Carcinoma; Cell Cycle; Cell Proliferation; Gene Expression Regulation, Neoplastic; Green Fluorescent Proteins; Humans; Imidazoles; Lung Neoplasms; Peptides; Piperazines; Proto-Oncogene Proteins c-mdm2; Recombinant Fusion Proteins; Tumor Cells, Cultured; Tumor Suppressor Protein p53