P53 In Cell Lines Research Articles

Reactive Oxygen Species-Mediated Apoptosis and Cytotoxicity of Newly Synthesized Pyridazin-3-Ones In P815 (Murin Mastocytoma) Cell Line.

In cancer cells, the intracellular antioxidant capacity and the redox homeostasis are mainly maintained by the glutathione- and thioredoxin-dependent systems which are considered as promising targets for anticancer drugs. Pyridazinones constitute an interesting source of heterocyclic compounds for drug discovery. The present investigation focused on studying the in-vitro antitumor activity of newly synthesized Pyridazin-3(2h)-ones derivatives against P815 (Murin mastocytoma) cell line. The in-vitro cytotoxic activities were investigated toward the P815 cell line using tetrazolium-based MTT assay. Lipid peroxidation and the specific activities of antioxidant enzymes were also determined. The newly compounds had a selective dose-dependent cytotoxic effect without affecting normal cells (PBMCs). Apoptosis was further confirmed through the characteristic apoptotic morphological changes and DNA fragmentation. Two compounds (6F: and 7H: ) were highly cytotoxic and were submitted to extend biological testing to determine the likely mechanisms of their cytotoxicity. Results showed that these molecules may induce cytotoxicity via disturbing the redox homeostasis. Importantly, the anticancer activity of 6F: and 7H: could be due to the intracellular reactive oxygen species hypergeneration through significant loss of glutathione reductase and thioredoxin reductase activities. This eventually leads to oxidative stress-mediated P815 cell apoptosis. Furthermore, the co-administration of 6F: or 7H: with Methotrexate exhibited a synergistic cytotoxic effect. considering their significant anticancer activity and chemosensitivity, 6F: and 7H: may improve the therapeutic efficacy of the current treatment for cancer.

MagA expression attenuates iron export activity in undifferentiated multipotent P19 cells.

Magnetic resonance imaging (MRI) is a non-invasive imaging modality used in longitudinal cell tracking. Previous studies suggest that MagA, a putative iron transport protein from magnetotactic bacteria, is a useful gene-based magnetic resonance contrast agent. Hemagglutinin-tagged MagA was stably expressed in undifferentiated embryonic mouse teratocarcinoma, multipotent P19 cells to provide a suitable model for tracking these cells during differentiation. Western blot and immunocytochemistry confirmed the expression and membrane localization of MagA in P19 cells. Surprisingly, elemental iron analysis using inductively-coupled plasma mass spectrometry revealed significant iron uptake in both parental and MagA-expressing P19 cells, cultured in the presence of iron-supplemented medium. Withdrawal of this extracellular iron supplement revealed unexpected iron export activity in P19 cells, which MagA expression attenuated. The influence of iron supplementation on parental and MagA-expressing cells was not reflected by longitudinal relaxation rates. Measurement of transverse relaxation rates (R2* and R2) reflected changes in total cellular iron content but did not clearly distinguish MagA-expressing cells from the parental cell type, despite significant differences in the uptake and retention of total cellular iron. Unlike other cell types, the reversible component R2′ (R2* ‒ R2) provided only a moderately strong correlation to amount of cellular iron, normalized to amount of protein. This is the first report to characterize MagA expression in a previously unrecognized iron exporting cell type. The interplay between contrast gene expression and systemic iron metabolism substantiates the potential for diverting cellular iron toward the formation of a novel iron compartment, however rudimentary when using a single magnetotactic bacterial gene expression system like magA. Since relatively few mammalian cells export iron, the P19 cell line provides a tractable model of ferroportin activity, suitable for magnetic resonance analysis of key iron-handling activities and their influence on gene-based MRI contrast.

Total Synthesis, Stereochemical Revision, and Biological Assessment of Iriomoteolide-2a.

Iriomoteolide-2a is a marine macrolide metabolite isolated from a cultured broth of the benthic dinoflagellate Amphidinium sp. HYA024 strain. This naturally occurring substance was reported to show remarkable cytotoxic activity against human cancer cell lines HeLa and DG-75 and in vivo antitumor activity against murine leukemia P388 cell line. Herein, the total synthesis, stereochemical revision, and biological assessment of iriomoteolide-2a are reported in detail. Total synthesis of the proposed structure 1 of iriomoteolide-2a featured a late-stage convergent assembly of three components by a Suzuki-Miyaura coupling, an esterification, and a ring-closing metathesis. However, the NMR data of synthetic 1 were not identical to those of the natural product. Careful analysis of the NMR data of the authentic material and synthesis/NMR analysis of appropriately designed model compounds led to consideration of four possible stereoisomers 2-5 as candidates for the correct structure. Accordingly, total syntheses of 2-5 were achieved by taking advantage of the convergent strategy, and comparison of the NMR spectra of synthetic 2-5 with those of the natural product led to the conclusion that 5 shows the correct relative configuration of iriomoteolide-2a. The absolute configuration of this natural product was finally established through chiral HPLC analysis of synthetic 5/ent-5 with the authentic sample. The antiproliferative activity of the synthetic compounds was assessed against HeLa and A549 cells to show that, in contrast to expectation, synthetic 5 and ent-5 were only marginally active in these cell lines. This work clearly underscores the vital role of total synthesis in the establishment of the structure and biological activity of natural products.

Neurogenesis Using P19 Embryonal Carcinoma Cells.

The P19 cell line derived from a mouse embryo-derived teratocarcinoma has the ability to differentiate into the three germ layers. In the presence of retinoic acid (RA), the suspension cultured P19 cell line is induced to differentiate into neurons. This phenomenon is extensively investigated as a neurogenesis model in vitro. Therefore, the P19 cell line is very useful for molecular and cellular studies associated with neurogenesis. However, protocols for neuronal differentiation of P19 cell line described in the literature are very complex. The method developed in this study are simple and will play a part in elucidating the molecular mechanisms in neurodevelopmental abnormalities and neurodegenerative diseases.

Cytotoxic Withanolides from the Whole Herb of Physalis angulata L.

Physalis angulata L. is a medicinal plant of the Solanaceae family, which is used to produce a variety of steroids. The present study reports on the cytotoxic withanolides of this plant. The species of Physalis angulata L. was identified by DNA barcoding techniques. Two new withanolides (1–2), together with six known analogues (3–8), were isolated from the whole plant of Physalis angulata L. The structures of these new compounds were determined on the basis of extensive spectroscopic data analyses and electronic circular dichroism (ECD) calculations. The withanolides exhibited strong cytotoxic activities against A549, Hela and p388 cell lines. Furthermore, compounds 1 and 2 induced typical apoptotic cell death in A549 cell line according to the evaluation of the apoptosis-inducing activity by flow cytometric analysis.

In Vitro Characterization of a Potent p53-MDM2 Inhibitor, RG7112 in Neuroblastoma Cancer Cell Lines.

Background: Neuroblastoma (NB) is one of the most aggressive and common solid tumors in pediatrics. Development of effective new therapeutics for NB is in progress to help reduce mortality and morbidity of the disease, particularly in relapsed patients. The tumor suppressor protein p53 plays a critical role in multiple signaling pathways to maintain cellular hemostasis. Dysregulation of p53 protein and/or molecular aberrations have been associated with multiple human malignancies. p53 stability and protein activity is negatively regulated by the E3 ubiquitin ligase (MDM2). Thus, targeting p53-MDM2 protein-protein interaction is a feasible and promising therapeutic strategy to restore the physiological function of p53 in cancer cells. RG7112 is a highly potent and selective small molecule inhibitor, which target a unique structure located within p53 binding motif of MDM2. Methods: The efficacy of RG7112 in vitro using NB cell lines was examined. Two wild-type (WT)-p53 NB cell lines IMR5 and LAN-5, a mutant p53 cell line SK-N-BE(2), and a WT-p53/p14 deleted cell line SH-EP were employed. Results: Data showed that RG7112 significantly reduced cellular viability of IMR5 (IC50, 562 nM) and LAN-5 (IC50, 430 nM), but not SK-N-BE(2) and SH-EP cells. Further, RG7112 restores p53 and p21 protein levels in IMR5 and LAN-5 in a dose-dependent manner. RG7112 induces cell cycle arresting (60% G1 arresting) in WT-p53 cells (IMR5), but no pronounced effect observed in SK-N-BE(2). In this study, 15 different drugs in combination with RG7112 in IMR5 cell line and identified venetoclax (Bcl-2/Bcl-xL inhibitor) as a promising candidate were evaluated. Conclusions: Taken together, these findings provide initial proof-of-concept data for further investigations of RG7112 in selected subgroups of NB patients.

The Effect of a Ferrocene Containing Camphor Sulfonamide DK-164 on Breast Cancer Cell Lines.

Drug resistance is a major cause of cancer treatment failure. Most cancer therapies involve multiple agents, to overcome it. Compounds that exhibit strong anti-tumor effect without damaging normal cells are more and more in the focus of research. Chemotherapeutic drugs, combining different moieties and functional groups in one molecule, can modulate different regulatory pathways in the cell and thus reach the higher efficacy than the agents, which affect only one cellular process. We tested the effect of recently synthesized ferrocene-containing camphor sulfonamide DK-164 on two breast cancer and one breast non-cancer cell lines. The cytotoxic effects were evaluated using the standard MTT-dye reduction and clonogenic assays. The apoptotic or autophagic effects were evaluated by Annexin v binding or LC3 puncta formation assays, respectively. Cell cycle arrest was determined using flow cytometry. Western blot and immunofluorescent analyses were used to estimate the localization and cellular distribution of key regulatory factors NFκB and p53. Compound DK-164 has well pronounced cytotoxicity greater to cancer cells (MDA-MB-231 and MCF-7) compared to non-cancerous (MCF-10A). The IC50 value of the substance caused a cell cycle arrest in G1 phase and induced apoptosis up to 24 hours in both tumor cells, although being more pronounced in MCF-7, a functional p53 cell line. Treatment with IC50 concentration of the compound provoked autophagy in both tumor lines but is better pronounced in the more aggressive cancer line (MDA-MB-231). The tested compound DK-164 showed promising properties as a potential therapeutic agent.

Optimizing gene set annotations combining GO structure and gene expression data

BackgroundWith the rapid accumulation of genomic data, it has become a challenge issue to annotate and interpret these data. As a representative, Gene set enrichment analysis has been widely used to interpret large molecular datasets generated by biological experiments. The result of gene set enrichment analysis heavily relies on the quality and integrity of gene set annotations. Although several methods were developed to annotate gene sets, there is still a lack of high quality annotation methods. Here, we propose a novel method to improve the annotation accuracy through combining the GO structure and gene expression data.ResultsWe propose a novel approach for optimizing gene set annotations to get more accurate annotation results. The proposed method filters the inconsistent annotations using GO structure information and probabilistic gene set clusters calculated by a range of cluster sizes over multiple bootstrap resampled datasets. The proposed method is employed to analyze p53 cell lines, colon cancer and breast cancer gene expression data. The experimental results show that the proposed method can filter a number of annotations unrelated to experimental data and increase gene set enrichment power and decrease the inconsistent of annotations.ConclusionsA novel gene set annotation optimization approach is proposed to improve the quality of gene annotations. Experimental results indicate that the proposed method effectively improves gene set annotation quality based on the GO structure and gene expression data.

Abstract A06: Cisplatin-induced DNA damage modifies the chromatin landscape of histone H2B monoubiquitination in a p53-dependent manner

Abstract Post-translational modifications (PTMs) of histone tails can function as epigenomic regulators of the cellular response to DNA damage. Monoubiquitination of histone H2B at lysine 120 (H2Bub1) is a central histone PTM involved in the DNA damage response. H2Bub1 localizes to double-strand breaks where it functions to decondense chromatin, making it accessible to DNA repair factors. H2Bub1 is also known to be enriched at coding sequences of highly expressed genes, demonstrating the fundamental importance of H2Bub1 for an open chromatin structure that facilitates transcription. H2Bub1 is a dynamic process, written predominantly by the E3 ubiquitin ligase complex of the ring finger proteins RNF20 and RNF40 and erased by multiple deubiquitinases, including those from the ubiquitin-specific peptidase subfamily USP7 and USP44. RNF20 is reported to interact with p53. Platinum drugs are used as standard-of-care for the treatment of high-grade serous ovarian cancer (HGSOC) based on their capacity to damage DNA. We sought to determine the response of ubiquitinated histone tails to a platinum drug with the goal of improving the efficacy of current best practice therapy for HGSOC. Following treatment of a wild-type p53 cell line with an IC75 dose of cisplatin, we combined H2Bub1 chromatin immunoprecipitation with massively parallel sequencing (ChIP-seq) to determine genomic enrichment of H2Bub1 in response to DNA damage. Further, we coupled this with RNA-seq (RNA sequencing) to enable correlation of genomic enrichment of H2Bub1 with levels of gene expression. KEGG pathway and gene ontology analyses demonstrated greatest H2Bub1 enrichment in response to DNA damage in p53 signalling pathway genes, including CDKN1A, BBC3, MDM2 and BAX. This correlated with increased expression of p53 target genes in response to DNA damage. Wild-type TP53 itself did not show H2Bub1 enrichment upon treatment with cisplatin. H2Bub1 ChIP experiments were repeated in HGSOC mutant p53 cell line models, specifically OVCAR-3 with the known gain-of-function TP53 mutation R248Q and Kuramochi with the missense TP53 mutation D281Y. H2Bub1 was not enriched in response to DNA damage at wild-type p53 gene targets in these cell lines, nor were these genes highly expressed. We therefore propose that DNA damage induced H2Bub1-enrichment in mutant p53 cell lines will have an entirely distinct genomic profile compared to wild-type p53 cell lines, with important roles in enabling the expression of mutant p53 target genes in HGSOC. Experiments are currently under way to directly address this hypothesis. Lastly, we have used clonogenic cell survival assays to demonstrate that downregulation of RNF20, either transiently using short interfering (si) RNA or stably,using short hairpin (sh) RNA, decreased the ability of HGSOC cells to survive treatment with cisplatin. Down-regulation of H2Bub1 by downregulation of its E3 ubiquitin ligase RNF20 may represent a novel treatment strategy to increase the efficacy of DNA damage-based therapy for HGSOC. Citation Format: Alexander J. Cole, Kristie-Ann Dickson, Christopher Liddle, Clare Stirzaker, Roderick Clifton-Bligh, Deborah J. Marsh. Cisplatin-induced DNA damage modifies the chromatin landscape of histone H2B monoubiquitination in a p53-dependent manner. [abstract]. In: Proceedings of the AACR Conference: Addressing Critical Questions in Ovarian Cancer Research and Treatment; Oct 1-4, 2017; Pittsburgh, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(15_Suppl):Abstract nr A06.

Mutant p53 gain of function induces HER2 over-expression in cancer cells

BackgroundHER2 over-expression is related with a poor prognosis in patients with invasive breast cancer tumors. Clinical associations have reported that somatic mutations of p53 more frequently detected in cases of sporadic breast cancer of the HER2 subtypes, besides a high percentage of HER2-amplifying tumors carry germline mutations of p53. The mechanisms responsible for the acquisition of oncogenic functions of p53 mutant proteins (mtp53), known as Gain of Function (GOF), over HER2 expression have not been reported. The objective of this study was to evaluate a possible relationship between p53 mutants and HER2 regulation.MethodsHER2 expression (transcription and protein), as well as HER2 protein stabilization have been evaluated after inducing or silencing of p53 mutants’ expression in cell lines. Finally, we evaluated the interaction of the p53 mutants over the HER2 receptor promoter.ResultsHigher HER2 expression in cell lines harboring endogenous mtp53 compared with wt or null expression of p53 cell lines. Transfection of p53 mutants (R248Q and R273C) in cell lines increased the expression of HER2. Silencing of p53 mutants, decrease HER2 expression. The p53 mutants R248Q and R273C significantly increase the luciferase activity on the HER2 promoter, and both mutants also promote acetylation of H3 and H4 histones binding in it.ConclusionsThese findings show for the first time that p53 mutants induce over-expression of HER2 at transcriptional level of the HER2 protein. Our results could have clinical implications in breast cancer and other types of cancer where HER2 is over-expressed and used as a therapy target.

Abstract 5523: Allele-specific restoration of biological function of the mutant p53 by Baylis-Hillman adducts

Abstract p53 is the most frequently mutated gene in human cancer, and the p53R175 mutant is the third most frequently found missense mutant that confers resistance to anticancer drugs and apoptosis. Therefore, small-molecule reactivation of mutant p53 function(s) represents an important and novel anticancer strategy. We have previously reported that induction of oxidative protein modifications primarily underlies the mechanistic conversion of mutant to wt or wt-like p53 forms (Eur J Medchem 107:233, 2016; Int J Oncol 48:1426, 2016). Here, we describe the identification of Baylis-Hillman (BH) adducts as potent and novel mutant p53 reactivators through cell-based, high-throughput small-molecule screening procedures. An extensive structure-activity relationship studies indicated that carbon-carbon double bond and the presence of an electron-withdrawing substituent at the aromatic ring were essential for the activity. Cell lines used in this study includes SKBR3, AU565 (p53R175H), MCF7 (p53 wt), MDA-MB-231 (p53del), MDA-MB-468 (p53R273H) and MCF10a normal breast epithelial cells. BH adducts displayed preferential cytotoxicity against cancer cells expressing the allele-specific R175H mutation (SKBR3 and AU565) in comparison with the wt p53 or p53-null cancer cell lines. Additionally, the BH adducts did not show significant cytotoxicity against normal cells (MCF10a). Further, we developed isogenic cell lines expressing the p53R175H in the p53-null H1299 lung cancer cells and evaluated their sensitivities towards BH adducts; these models again verified the greater drug efficacy. To prove the hypothesis the higher efficacy of BH adduct stems from the reactivation of mutant p53, the conformation-specific antibodies (Pab1620 for wt and Pab420 for mutant) were employed. Immunoprecipitation and immunostaining using confocal microscopy showed that BH adduct treatment of p53R175H cells resulted in a marked reciprocal loss of mutant protein and gradual increase of wt-like protein. EMSA revealed a time-dependent restoration of DNA-binding of the mutant p53, which was accompanied by a distinct upregulation of pro-apoptotic signaling pathways mediated by PUMA, Bax, p21cip1 and MDM2 proteins. A strong G2/M arrest and significant apoptosis were observed with BH adduct in a time and concentration-dependent manner. Other data showed that BH adduct restores the wt-structure and function by covalently binding with the mutant p53R175H. In conclusion, BH adduct is an attractive lead compound for further development because of its potent p53 reactivation of nonfunctional mutant protein (supported by CPRIT grants RP130266 and RP170207 to KSS). Citation Format: Surendra R. Punganuru, Viswanath Arutla, Hanumantha Rao Madala, Kalkunte S. Srivenugopal. Allele-specific restoration of biological function of the mutant p53 by Baylis-Hillman adducts [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5523.

Abstract 3954: Anti-cancer agent P306 restores p53 pathway through PUMA

Abstract The tumor-suppressor p53 prevents cancer development via initiating cell-cycle arrest, cell death, repair, or anti-angiogenesis processes. Over 50% of human cancers harbor cancer-causing mutations in p53. p53 mutations not only abrogate its tumor-suppressor function, but also endow mutant p53 with a gain of function (GOF), creating a proto-oncogene that contributes to tumorigenesis, tumor progression, and chemo- or radiotherapy resistance. Thus, targeting mutant p53 and/or restoring a wild-type p53 signaling pathway provides an attractive strategy for cancer therapy. We previously showed that P01, a natural product, has potent anti-cancer activity against tumors with mutated p53. Based on the structure of the pharmacophore of the P01 family, we designed and synthesized new analogues. The novel synthetic analogue, P306, is potent in reducing both short-term and long-term proliferation in a broad panel of mutant p53 cell lines, including HT29, SW480, DLD-1, MDA-MB-231, MDA-MB-468, U251, FaDu, CAL-27, PANC-1, ASPC-1 and H1975, with IC50 values in the range of 33.9 to 242 nM. In this study, we have characterized a distinct mechanism of P306 that engages the apoptosis pathway by upregulating pro-apoptotic proteins including PUMA in a time-and dose-dependent manner in colorectal cancer cell lines. PUMA is necessary for the apoptotic effects of P306 in colorectal cancer cells with PUMA-mediated caspase 8 activation mediating P306-induced apoptosis. P306 not only restores p53 pathway but also depletes mutant p53 protein in various mutant p53-expressing cancer cells regardless of what kinds of mutation. P306 treatment potently downregulates c-Myc protein level, and apoptosis induced by P306 is dependent on the c-Myc-PUMA pathway. Our results provide novel mechanistic insights into the tumor cell death promoting activity of a candidate therapeutic agent for cancer. Citation Format: Xiaobing Tian, Amriti R. Lulla, Shengling Zhang, Avital Lev, Philip Abbosh, Rahmat Sikder, David T. Dicker, Wafik S. El-Deiry. Anti-cancer agent P306 restores p53 pathway through PUMA [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3954.

Cytotoxic Profiling of Endogenous Metabolites Relevant to Chronic Fatigue Immune Dysfunction Syndrome (CFIDS) on p53 Variant Human Colon Carcinoma Cell Lines.

Chemoprophylatic strategies against development of multifactorial diseases utilize compounds to block the multistep events in chronic inflammation and carcinogenesis. The successful chemopreventative candidate must therefore selectively inhibit growth of transformed cells and be administered frequently to confer maximal protection with minimal side effects. In addition to synthetic and exogenous natural compounds, endogenous metabolites represent another class of compounds that exhibit anticarcinogenic and anti-inflammatory properties contributing to proper cell function. To assess the effectiveness of these compounds warrants an understanding of their cytotoxic mode of action. In this study, p53 variant human colon carcinoma cell lines were chronically exposed to varying concentrations of the endogenous metabolites—phenyl acetate, ursodeoxycholate, and tauroursodeoxycholate—to determine the role of p53-induced cytotoxicity, with p53 mutant and deficient cell lines representing precancerous lesions. Cytotoxicity was assessed using clonogenic assays, and macroscopic colony counts were used to quantify cell survival. The results demonstrate that the bile acids, ursodeoxycholate and tauroursodeoxycholate, exhibit selective cytotoxicity toward nonfunctional p53 cell lines suggesting a p53-mediated role in inhibition of cell clonogenicity and potential chemopreventative properties. Although each compound displays this described effect, the tauroursodeoxycholate demonstrates high significance suggesting it might have practical uses in vivo.

Elucidation of the Relationship between CD Cotton Effects and the Absolute Configuration of Sixteen Stereoisomers of Spiroheterocyclic-Lactams.

As part of research to search for antitumor agents in fungi originating from marine organisms, cephalimysins E–L were isolated from a culture broth of Aspergillus fumigatus that was separated from the marine fish Mugil cephalus. One- and two-dimensional nuclear magnetic resonance spectra revealed their planar structures, which are diastereomers of each other. Their absolute stereostructures were established by epimerization at C-8 with acidic methanol, nuclear Overhauser effect spectroscopy (NOESY), and circular dichroism (CD) spectroscopy. These demonstrated the detailed relationships between absolute configuration and CD Cotton effects. Additionally, in the growth inhibition assay against P388, HL-60, L1210, and KB cell lines, some of the fungal metabolites or reaction products exhibited moderate activities.

Resveratrol prevents p53 aggregation in vitro and in breast cancer cells.

One potential target for cancer therapeutics is the tumor suppressor p53, which is mutated in more than 50% of malignant tumors. Loss of function (LoF), dominant negative (DN) and gain of function (GoF) mutations in p53 are associated with amyloid aggregation. We tested the potential of resveratrol, a naturally occurring polyphenol, to interact and prevent the aggregation of wild-type and mutant p53 in vitro using fluorescence spectroscopy techniques and in human breast cancer cells (MDA-MB-231, HCC-70 and MCF-7) using immunofluorescence co-localization assays. Based on our data, an interaction occurs between resveratrol and the wild-type p53 core domain (p53C). In addition, resveratrol and its derivatives pterostilbene and piceatannol inhibit mutant p53C aggregation in vitro. Additionally, resveratrol reduces mutant p53 protein aggregation in MDA-MB-231 and HCC-70 cells but not in the wild-type p53 cell line MCF-7. To verify the effects of resveratrol on tumorigenicity, cell proliferation and cell migration assays were performed using MDA-MB-231 cells. Resveratrol significantly reduced the proliferative and migratory capabilities of these cells. Our study provides evidence that resveratrol directly modulates p53, enhancing our understanding of the mechanisms involved in p53 aggregation and its potential as a therapeutic strategy for cancer treatment.

Mitochondrial ROS direct the differentiation of murine pluripotent P19 cells

ROS are frequently associated with deleterious effects caused by oxidative stress. Despite the harmful effects of non-specific oxidation, ROS also function as signal transduction molecules that regulate various biological processes, including stem cell proliferation and differentiation. Here we show that mitochondrial ROS level determines cell fate during differentiation of the pluripotent stem cell line P19. As stem cells in general, P19 cells are characterized by a low respiration activity, accompanied by a low level of ROS formation. Nevertheless, we found that P19 cells contain fully assembled mitochondrial electron transport chain supercomplexes (respirasomes), suggesting that low respiration activity may serve as a protective mechanism against ROS. Upon elevated mitochondrial ROS formation, the proliferative potential of P19 cells is decreased due to longer S phase of the cell cycle. Our data show that besides being harmful, mitochondrial ROS production regulates the differentiation potential of P19 cells: elevated mitochondrial ROS level favours trophoblast differentiation, whereas preventing neuron differentiation. Therefore, our results suggest that mitochondrial ROS level serves as an important factor that directs differentiation towards certain cell types while preventing others.

Delanzomib Interacts with Ritonavir Synergistically to Cause Endoplasmic Reticulum Stress in Renal Cancer Cells.

To investigate the efficacy against renal cancer cells of combining the HIV protease inhibitor ritonavir with the novel proteasome inhibitor delanzomib. Renal cancer cell lines 769-P, 786-O, Caki-2 and Renca were treated with ritonavir and delanzomib in vitro and in vivo, and the efficacy of combination was evaluated. The combination of ritonavir and delanzomib synergistically inhibited renal cancer growth and suppressed colony formation. It induced robust apoptosis evidenced by increased cell population in the sub-G1 fraction and increased number of annexin-V-positive cells. A 13-day treatment with the combination was well tolerated in the mouse model and inhibited tumor growth significantly. Mechanistically, the combination synergistically induced endoplasmic reticulum stress and inhibited the mammalian target of rapamycin (mTOR) pathway. The effectiveness of combination of ritonavir and delanzomib appears to be due to the induction of ER stress and inhibition of the mTOR pathway.

Increased IL-27/IL-27R expression in association with the immunopathology of murine ocular toxoplasmosis.

Interleukin 27 (IL-27) is a member of the IL-6/IL-12 family, and IL-27 receptor (IL-27R) consists of WSX-1 (the IL-27Rα subunit) and the signal-transducing subunit gp130. Human and mouse mast cells (MCs) express the IL-27R. To explore the expressions of IL-27/IL-27R subunits (WSX-1 and gp130) during acute ocular toxoplasmosis (OT), we established mouse model by intraocular injection of 500 Toxoplasma gondii RH strain tachyzoites. Histopathological changes were analyzed, MCs were counted by toluidine blue staining, and tryptase+/IL-27+ MCs were examined by immunofluorescence double-staining in the eyes and cervical lymph nodes (CLNs) of T. gondii-infected mice. The mRNA expressions of IL-27p28, WSX-1, gp130, and tachyzoite specific surface antigen 1 (SAG1) in the eyes and CLNs of T. gondii-infected mice, and the expressions of WSX-1 and gp130 in the murine mastocytoma cell line P815 infected with T. gondii tachyzoites in vitro were examined by using quantitative real-time reverse transcription-polymerase chain reaction. Our results showed that, after T. gondii infection, severe histopathological changes, increased numbers of total MCs and degranulated MCs, elevated expressions of IL-27p28, WSX-1, and gp130 were found in the eyes and CLNs, and significant correlations between the levels of IL-27 and SAG1 existed in the eyes and CLNs of T. gondii-infected mice. In addition, increased levels of WSX-1 and gp130 were examined in T. gondii-infected P815 cells. Our data suggested that IL-27/IL-27R expression induced by T. gondii infection may regulate MC-mediated immune response during acute OT in mouse model.

Autocatalytic synthesis of 3-ethyl-3-hydroxy-indole-2-ones and their neuroprotection and antitumor activities' evaluation

In this study, a series of 3-ethyl-3-hydroxy-indole-2-ones were synthesized through the addition reaction of Et 2 Zn and N-substituted isatin by an autocatalytic process. The synthesized compounds were characterized by NMR spectroscopy and mass spectrometry, and the reaction mechanism was discussed. The antitumor and neuroprotection activities of these compounds were evaluated. The results showed that several compounds display protection activity on H 2 O 2 -induced apoptosis of PC12 cells, which are more effective than that of (±)-α-tocopherol Vitamin E (VE). Moreover, these compounds also show antitumor activity against A549 and P388 cell lines.

Inverse expression of survivin and reprimo correlates with poor patient prognosis in gastric cancer.

BACKGROUNDThe objective of the study was to determine the relationship between Survivin and Reprimo transcript/protein expression levels, and gastric cancer outcome.METHODSIn silico correlations between an agnostic set of twelve p53-dependent apoptosis and cell-cycle genes were explored in the gastric adenocarcinoma TCGA database, using cBioPortal. Findings were validated by regression analysis of RNAseq data. Separate regression analyses were performed to assess the impact of p53 status on Survivin and Reprimo. Quantitative reverse-transcription PCR (RT-qPCR) and immunohistochemistry confirmed in silico findings on fresh-frozen and paraffin-embedded gastric cancer tissues, respectively. Wild-type (AGS, SNU-1) and mutated p53 (NCI-N87) cell lines transfected with pEGFP-Survivin or pCMV6-Reprimo were evaluated by RT-qPCR and Western blotting. Kaplan-Meier method and Long-Rank test were used to assess differences in patient outcome.RESULTScBioPortal analysis revealed an inverse correlation between Survivin and Reprimo expression (Pearson’s r= −0.3, Spearman’s ρ= −0.55). RNAseq analyses confirmed these findings (Spearman’s ρ= −0.37, p<4.2e-09) and revealed p53 dependence in linear regression models (p<0.05). mRNA and protein levels validated these observations in clinical samples (p<0.001). In vitro analysis in cell lines demonstrated that increasing Survivin reduced Reprimo, while increasing Reprimo reduced Survivin expression, but only did so in p53 wild-type gastric cells (p<0.05). Survivin-positive but Reprimo-negative patients displayed shorter overall survival rates (p=0.047, Long Rank Test) (HR=0.32; 95%IC: 0.11-0.97; p=0.044).CONCLUSIONSTCGA RNAseq data analysis, evaluation of clinical samples and studies in cell lines identified an inverse relationship between Survivin and Reprimo. Elevated Survivin and reduced Reprimo protein expression correlated with poor patient prognosis in gastric cancer.