Cellular Growth Inhibition Research Articles

LeftyA sensitive cytosolic pH regulation and glycolytic flux in Ishikawa human endometrial cancer cells

ObjectiveLeftyA, a powerful regulator of stemness, embryonic differentiation, and reprogramming of cancer cells, counteracts cell proliferation and tumor growth. Key properties of tumor cells include enhanced glycolytic flux, which is highly sensitive to cytosolic pH and thus requires export of H+ and lactate. H+ extrusion is in part accomplished by Na+/H+ exchangers, such as NHE1. An effect of LeftyA on transport processes has, however, never been reported. The present study thus explored whether LeftyA modifies regulation of cytosolic pH (pHi) in Ishikawa cells, a well differentiated endometrial carcinoma cell model. MethodsNHE1 transcript levels were determined by qRT-PCR, NHE1 protein abundance quantified by Western blotting, pHi estimated utilizing (2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein [BCECF] fluorescence, Na+/H+ exchanger activity from Na+ dependent realkalinization after an ammonium pulse, and lactate concentration in the supernatant utilizing an enzymatic assay and subsequent colorimetry. ResultsA 2 h treatment with LeftyA (8 ng/ml) significantly decreased NHE1 transcript levels (by 99.6%), NHE1 protein abundance (by 71%), Na+/H+ exchanger activity (by 55%), pHi (from 7.22 ± 0.02 to 7.05 ± 0.02), and lactate release (by 41%). ConclusionsLeftyA markedly down-regulates NHE1 expression, Na+/H+ exchanger activity, pHi, and lactate release in Ishikawa cells. Those effects presumably contribute to cellular reprogramming and growth inhibition.

MicroRNA biogenesis and cellular proliferation

Given the fundamental roles of microRNAs (miRNAs) in physiological, developmental, and pathologic processes, we hypothesized that genes involved in miRNA biogenesis contribute to human complex traits. For 13 such genes, we evaluated the relationship between transcription and 2 classes of complex traits, namely cellular growth and sensitivity to various chemotherapeutic agents in a set of lymphoblastoid cell lines. We found a highly significant correlation between argonaute RNA-induced silencing complex catalytic component 2 (AGO2) expression and cellular growth rate (Bonferroni-adjusted P < 0.05), and report additional miRNA biogenesis genes with suggestive associations with either cellular growth rate or chemotherapeutic sensitivity. AGO2 expression was found to be correlated with multiple drug sensitivity phenotypes. Furthermore, small interfering RNA knockdown of AGO2 resulted in cellular growth inhibition in an ovarian cancer cell line (OVCAR-3), supporting the role of this miRNA biogenesis gene in cell proliferation in cancer cells. Expression quantitative trait loci mapping indicated that genetic variation (in the form of both single-nucleotide polymorphisms and copy number variations) that may regulate the expression of AGO2 can have downstream effects on cellular growth-dependent complex phenotypes.

Cytotoxic activity of ten algae from the Persian Gulf and Oman Sea on human breast cancer cell lines; MDA-MB-231, MCF-7, and T-47D.

Background:Seaweeds have proven to be a promising natural source of bioactive metabolites for drug development.Objective:This study aimed to monitor the ethanol extract of ten algae from the Persian Gulf and Oman Sea, for their in vitro cytotoxic activity on three human breast cancer cell lines.Materials and Methods:Three human breast cancer cell lines including MDA-MB-231(ER−), MCF-7(ER+), and T-47D (ER+) were treated by different concentrations of total ethanol (90%) algae extracts and the cytotoxic effects were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Doxorubicin (Ebewe, Austria) was used as a positive control. After 72 h of incubation, the cytotoxic effect of the algae was calculated and presented as 50%-inhibitory concentration (IC50).Results:The results indicated Gracilaria foliifera and Cladophoropsis sp. to be the most active algae in terms of cytotoxic effects on the investigated cancer cell lines. The IC50 values against MDA-MB-231, MCF-7, and T-47D cells were, respectively, 74.89 ± 21.71, 207.81 ± 12.07, and 203.25 ± 30.98 µg/ml for G. foliifera and 66.48 ± 4.96, 150.86 ± 51.56 and >400 µg/ml for Cladophoropsis sp. The rest of the algal extracts were observed not to have significant cytotoxic effects in the concentration range from 6.25 µg/ml to 400 µg/ml.Conclusion:Our data conclusively suggest that G. foliifera and Cladophoropsis sp. may be good candidates for further fractionation to obtain novel anticancer substances. Moreover, stronger cytotoxic effects on estrogen negative breast cancer cell line (MDA-MB-231(ER−)) in comparison to estrogen positive cells (MCF-7 and T-47D) suggest that the extract of G. foliifera and Cladophoropsis sp. may have an estrogen receptor/progesterone receptor-independent mechanism for their cellular growth inhibition.

A novel therapeutic combination sequentially targeting aurora B and Bcl-xL in hepatocellular carcinoma.

Effective therapeutic combinations targeting the oncogenic pathway still are unknown in human hepatocellular carcinoma (HCC). The authors previously identified aberrant expression of aurora B kinase as the independent predictor for the lethal recurrence of HCC, showing that AZD1152 induced in vitro and in vivo apoptosis with polyploidy in human HCC cells. In this preclinical study, the combined effects of molecular-targeted therapies were evaluated based on the cellular response of aurora B inhibition. This study analyzed the expression of Bcl-2 family proteins in polyploidization induced by AZD1152 and the in vitro synergistic effects of AZD1152 with control of the Bcl-2 family pathway in human HCC cells. The in vivo effects of the combination therapy targeting the specific molecules were evaluated using subcutaneous tumor xenograft models. The findings showed that Bcl-xL was specifically overexpressed in AZD1152-induced polyploid HCC cells. The combination of AZD1152 followed by Bcl-xL/2 inhibitor ABT263 induced synergistically cellular apoptosis (p < 0.001) and growth inhibition (p < 0.0001). Interestingly, the reverse sequential administration of AZD1152 combined with pretreatment of ABT263 was less effective than the original one. In vivo studies using tumor xenografts of human HCC cells showed that combination therapy of ABT263 after AZD1152 pretreatment induced significant intratumoral apoptosis (p < 0.05) and remarkable anti-tumor effects (p < 0.05) without a severe adverse effect compared with the monotherapy. Based on Bcl-xL overexpression in polyploidy induced by aurora B inhibition, the rationale for therapeutic combinations targeting aurora B and Bcl-xL was demonstrated in the authors' preclinical studies, leading to a promising novel approach for the mechanism-based treatment of human HCC.

Identifying and validating a combined mRNA and microRNA signature in response to imatinib treatment in a chronic myeloid leukemia cell line.

Imatinib, a targeted tyrosine kinase inhibitor, is the gold standard for managing chronic myeloid leukemia (CML). Despite its wide application, imatinib resistance occurs in 20–30% of individuals with CML. Multiple potential biomarkers have been identified to predict imatinib response; however, the majority of them remain externally uncorroborated. In this study, we set out to systematically identify gene/microRNA (miRNA) whose expression changes are related to imatinib response. Through a Gene Expression Omnibus search, we identified two genome-wide expression datasets that contain expression changes in response to imatinib treatment in a CML cell line (K562): one for mRNA and the other for miRNA. Significantly differentially expressed transcripts/miRNAs post imatinib treatment were identified from both datasets. Three additional filtering criteria were applied 1) miRbase/miRanda predictive algorithm; 2) opposite direction of imatinib effect for genes and miRNAs; and 3) literature support. These criteria narrowed our candidate gene-miRNA to a single pair: IL8 and miR-493-5p. Using PCR we confirmed the significant up-regulation and down-regulation of miR-493-5p and IL8 by imatinib treatment, respectively in K562 cells. In addition, IL8 expression was significantly down-regulated in K562 cells 24 hours after miR-493-5p mimic transfection (p = 0.002). Furthermore, we demonstrated significant cellular growth inhibition after IL8 inhibition through either gene silencing or by over-expression of miR-493-5p (p = 0.0005 and p = 0.001 respectively). The IL8 inhibition also further sensitized K562 cells to imatinib cytotoxicity (p<0.0001). Our study combined expression changes in transcriptome and miRNA after imatinib exposure to identify a potential gene-miRNA pair that is a critical target in imatinib response. Experimental validation supports the relationships between IL8 and miR-493-5p and between this gene-miRNA pair and imatinib sensitivity in a CML cell line. Our data suggests integrative analysis of multiple omic level data may provide new insight into biomarker discovery as well as mechanisms of imatinib resistance.

TP53-induced glycolysis and apoptosis regulator promotes proliferation and invasiveness of nasopharyngeal carcinoma cells.

The TP53-induced glycolysis and apoptosis regulator (TIGAR) is the protein product of the p53 target gene, C12orf5. TIGAR blocks glycolysis and promotes cellular metabolism via the pentose phosphate pathway; it promotes the production of cellular nicotinamide adenine dinucleotide phosphate (NADPH), which leads to enhanced scavenging of intracellular reactive oxygen species, and inhibition of oxidative stress-induced apoptosis in normal cells. Our previous study identified a novel nucleoside analog that inhibited cellular growth and induced apoptosis in nasopharyngeal carcinoma (NPC) cell lines via downregulation of TIGAR expression. Furthermore, the growth inhibitory effects of c-Met tyrosine kinase inhibitors were ameliorated by the overexpression of TIGAR in the NPC cell lines. These results indicate a significant role for TIGAR expression in the survival of NPCs. The present study aimed to further define the function of TIGAR expression in NPC cells. In total, 36 formalin-fixed, paraffin-embedded NPC tissue samples were obtained for the immunohistochemical determination of TIGAR expression. The effects of TIGAR expression on cell proliferation, NADPH production and cellular invasiveness were also assessed in NPC cell lines. Overall, TIGAR was overexpressed in 27/36 (75%) of the NPC tissues compared with the adjacent non-cancer epithelial cells. Similarly, TIGAR overexpression was also observed in a panel of six NPC cell lines compared with normal NP460 hTert and Het1A cell lines. TIGAR overexpression led to increased cellular growth, NADPH production and invasiveness of the NPC cell lines, whereas a knockdown of TIGAR expression resulted in significant inhibition of cellular growth and invasiveness. The expression of the two mesenchymal markers, fibronectin and vimentin, was increased by TIGAR overexpression, but reduced following TIGAR-knockdown. The present study revealed that TIGAR overexpression led to increased cellular growth, NADPH production and invasiveness, and the maintenance of a mesenchymal phenotype, in NPC tissues.

Bone Marrow Failure in Fanconi Anemia from Hyperactive TGF-β Signaling

Fanconi anemia (FA) is the most common inherited bone marrow failure syndrome. FA patients develop bone marrow failure during the first decade of life due to attrition of hematopoietic stem and progenitor cells (HSPCs). FA patients also develop other hematologic manifestations, including myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) due to clonal evolution. FA is caused by biallelic mutants in one of sixteen FANC genes, the products of which cooperate in the FA/BRCA DNA repair pathway and regulate cellular resistance to DNA cross-linking agents. Bone marrow failure in FA may result, directly or indirectly, from hyperactivation of cell autonomous or microenvironmental growth suppressive pathways induced due to genotoxic stress. Recent studies suggest that one suppressive pathway may be the hyperactive p53 response observed in HSPCs from FA patients.In order to further identify suppressive mechanisms accounting for bone marrow failure in FA, we performed a whole genome-wide shRNA screen in FA cells. Specifically, we screened for candidate genes whose knockdown would rescue cellular growth inhibition and genotoxic stress induced by a DNA cross-linking agent mitomycin C (MMC). We transduced a FA-deficient human fibroblast line with pools of shRNAs and screened for rescue of MMC-inhibited growth. Selected shRNA inserts were identified by next generation sequencing.The top hits in the screen were shRNAs directed against multiple components of the TGF-β signaling pathway. Consistent with this, disruption of the TGF-β signaling pathway by shRNA/sgRNA-mediated knockdown of SMAD3 or TGFR1 (downstream components of the TGF- β pathway) rescued growth of multiple cell lines from several FA complementation groups in presence of genotoxic agents (e.g. MMC or acetaldehyde). Pharmacologic inhibition of the TGF- β pathway using small molecule inhibitors resulted in improved survival of FA-deficient lymphoblast cells in presence of MMC or acetaldehyde, suggesting that a hyperactive, TGF-β-mediated, suppression pathway may account, at least in part, for reduced FA cell growth. Interestingly, genes encoding TGF-β pathway signaling components were highly expressed in the bone marrow from FA patients and FA mice. Moreover, disruption of the TGF- β pathway by shRNA-mediated knockdown of SMAD3 rescued the growth defects of primary HSPCs from FA-deficient murine bone marrow. To further implicate the TGF-β pathway, we established primary stromal cell lines from the bone marrow of FA-deficient mice as well as human FA patients. We confirmed that TGF-β signaling was hyperactive in these stroma cells resulting in growth suppression and elevated phospho-ERK levels due to non-canonical signaling of the pathway. Inhibitors of TGF-β signaling partially rescued the growth defects and reduced phospho-ERK levels in these FA stroma cells.The deficiency of FA DNA repair pathway leads to cellular defects in homologous recombination (HR) repair and hyperactivation of toxic non-homologous end joining (NHEJ)-mediated repair. We therefore tested whether inhibition of the TGF-β pathway in FA cells could rescue HR defects and account for the improvement of FA cellular growth. Interestingly, disruption of the TGF-β signaling pathway caused a decrease in NHEJ activity. Disruption of the TGF-β pathway also resulted in reduced MMC-mediated DNA damage and increased HR.Taken together, our results demonstrate that primary FA hematopoietic and bone marrow stromal cells exhibit hyperactive TGF-β signaling accounting at least in part for the bone marrow failure in FA. Inhibitors of the TGF-β signaling pathway may therefore be useful in the clinical treatment of patients with bone marrow failure and Fanconi anemia. DisclosuresNo relevant conflicts of interest to declare.

Microbial screening for quinolones residues in cow milk by bio-optical method

The use of antibiotics on lactating cows should be monitored for the possible risk of milk contamination with residues. Accordingly, Maximum Residue Levels (MRLs) are established by the European Commission to guarantee consumers safety. As pointed out by Dec 2002/657/EC, screening is the first step in the strategy for antibiotic residue control, thus playing a key role in the whole control procedure. However, current routine screening methods applied in milk chain still fail to detect residues of quinolones at concentrations of interest.This paper reports the findings of a new bio-optical method for the screening of quinolones residues in bovine milk, based on E. coli ATCC 11303 growth inhibition.The effect of blank and spiked cow milk samples (aliquots equivalents to 0.8%, v/v) is evaluated in Mueller Hinton Broth (MHb) and MHb enriched with MgSO4 2% (MHb-Mg) inoculated with the test strain at the concentration of 104CFU/mL.The presence of quinolones inhibits the cellular growth in MHb, while this effect is neutralized in MHb-Mg allowing both detection and presumptive identification of quinolones.Growth of the test strain is monitored at 37°C in a Bioscreen C automated system, and Optical Density (OD) at 600nm is recorded every 10min after shaking for 10s. Growth curves (OD vs. time) of E. coli ATCC 11303 are assessed in milk samples, with and without quinolones, and their differences in terms of ΔOD (ΔOD600nm=ODMHb-Mg−ODMHb) are calculated.The presence of quinolones is detected by the cellular growth inhibition (OD vs time, none increase in the value OD) and presumptively identified through the increase of the slope of ΔOD600nm curve (ΔOD vs. time), after about 3h of incubation.The detection limit for ciprofloxacin and enrofloxacin is at the level of MRL, for marbofloxacin is at 2-fold the MRL whereas for danofloxacin is at 4-fold the MRL. Although the sensitivity of the method could be further improved and the procedure automated, it is a promising step forward to integrate screening assays into the control process and, in particular, to fill in the gap for quinolones; moreover, these technological developments contribute to the One Health perspective through the monitoring of safe and correct use of veterinary antibiotics.

Nardostachys chinensis induces granulocytic differentiation with the suppression of cell growth through p27Kip1 protein-related G0/G1 phase arrest in human promyelocytic leukemic cells

Context: Nardostachys chinensis Batalin (Valerianaceae) has been used in Korean traditional medicine to elicit stomachic and sedative effects. However, the anti-leukemic activities of N. chinensis have not been well examined.Objective: To investigate the effect of N. chinensis on differentiation and proliferation in the human promyelocytic leukemic HL-60 cells.Materials and methods: The dried roots and stems of N. chiensis are extracted using hot water and then freeze-dried. The yield of extract was 12.82% (w/w). The HL-60 cells were treated with 25–200 μg/ml of N. chinensis for 72 h or 100 μg/ml of N. chinensis for 24–72 h.Results: Nardostachys chinensis significantly inhibited cell viability dose dependently with an IC50 of 100 μg/ml in HL-60 cells. Nardostachys chinensis induced differentiation of the cells as measured by reduction activity of NBT and expression of CD11b but not of CD14 as analyzed by flow cytometry, which indicates a differentiation toward the granulocytic lineage. Nardostachys chinensis also induced growth inhibition through G0/G1 phase arrest in the cell cycle of HL-60 cells. Among the G0/G1 phase in the cell cycle-related protein, the expression of cyclin-dependent kinase (CDK) inhibitor p27Kip1 was increased in N. chinensis-treated HL-60 cells, whereas the expression levels of CDK2, CDK4, CDK6, cyclin D1, cyclin D3, cyclin E, and cyclin A were decreased. Interestingly, N. chinensis markedly enhanced the binding of p27Kip1 with CDK2 and CDK6.Discussion and conclusion: This study demonstrated that N. chinensis is capable of inducing cellular differentiation and growth inhibition through p27Kip1 protein-related G0/G1 phase arrest in HL-60 cells.

Modified 2,4-diaminopyrimidine-based dihydrofolate reductase inhibitors as potential drug scaffolds against Bacillus anthracis

The current Letter describes the synthesis and biological evaluation of dihydrophthalazine-appended 2,4-diaminopyrimidine (DAP) inhibitors (1) oxidized at the methylene bridge linking the DAP ring to the central aromatic ring and (2) modified at the central ring ether groups. Structures 4a–b incorporating an oxidized methylene bridge showed a decrease in activity, while slightly larger alkyl groups (CH2CH3 vs CH3) on the central ring oxygen atoms (R2 and R3) had a minimal impact on the inhibition. Comparison of the potency data for previously reported RAB1 and BN-53 with the most potent of the new derivatives (19b and 20a–b) showed similar values for inhibition of cellular growth and direct enzymatic inhibition (MICs 0.5–2μg/mL). Compounds 29–34 with larger ester and ether groups containing substituted aromatic rings at R3 exhibited slightly reduced activity (MICs 2–16μg/mL). One explanation for this attenuated activity could be encroachment of the extended R3 into the neighboring NADPH co-factor. These results indicate that modest additions to the central ring oxygen atoms are well tolerated, while larger modifications have the potential to act as dual-site inhibitors of dihydrofolate reductase (DHFR).

Abstract LB-135: Selective small molecule inhibition of the N-terminal BET bromodomain

Abstract Introduction: The bromodomain acetyl-lysine ‘readers’ is an emerging target class with particular interest centered around the BET family proteins BRD2, 3, and 4. Pre-clinical target validation experiments of BET proteins using genetic tools and/or small molecule bromodomain inhibitors have demonstrated strong disease linkage in several cancers, and a number of BET inhibitors are currently in early clinical trials within oncology. BET proteins contain a unit of tandem bromodomains (BD1 and BD2), each capable of binding to acetylated lysines within partner proteins. However, the contribution of individual bromodomains and of specific BET isoforms to biological activity is currently unclear, and domain-specific inhibition (intra- and/or inter-BET) of BET proteins has been insufficiently explored. Here we report and characterize the first BD1-selective BET inhibitors. Methods: Chemetics DNA-encoding small molecule libraries was used to identify small molecule BET inhibitors. Binding of hit compounds to bromodomains was investigated using AlphaScreen and FRET assays. Compounds were then assayed for AML cell growth inhibition using MTS and CellTiter-Glo assays, and for inhibition of cytokine release from human PBMCs following LPS stimulation. Results: To discover novel inhibitors of BET bromodomains, we screened ∼300 million small molecule compounds for binding towards BD1 of human BRD4. Representative hits from several chemical series were resynthesized and confirmed for binding to BRD4 in the high nM range. Chemical optimization of one series yielded compounds with low nM affinity against BRD4 BD1 with comparable affinity against the BD1s of other BET proteins. Interestingly, the compounds display marked intra-BET BD selectivity, with a strong preference (10-40 fold) for binding to BD1. In cellular growth inhibition assays, the compounds selectively target MLL-translocated AML cell lines. LPS-induced cytokine release from human PBMCs is strongly inhibited by both the pan-BET inhibitors JQ-1/I-BET762 and our BD1-selective compounds. In contrast, the BD2-selective compound RVX-208 show limited activity in the cell models tested here. Conclusions: Using DNA-encoding technology, we discovered low nM small molecule compounds that selectively inhibit the first bromodomain of BET proteins. The compounds strongly inhibit BET-dependent cellular processes. Furthermore, our data suggest that a number of BET biological activities are mediated pimarily by BD1, and that BD1 blockade is sufficient to elicit BET inhibition. Efforts to understand the mechanism and potential therapeutic utility of BD1-selectivity are ongoing. Citation Format: Jimmi G. Seitzberg, Margit H. Hansen, Tine T. Akinleminu Kronborg, Christina R. Underwood, Gitte Friberg, Berit Tonnesen, Lene Teuber, Thomas Franch, Søren J. Nielsen. Selective small molecule inhibition of the N-terminal BET bromodomain. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr LB-135. doi:10.1158/1538-7445.AM2014-LB-135

Size-controlled biodegradable nanoparticles: Preparation and size-dependent cellular uptake and tumor cell growth inhibition

Biodegradable nanoparticles with diameters below 1000nm are of great interest in the contexts of targeted delivery and imaging. In this study, we prepared PLGA nanoparticles with well-defined sizes of ∼70nm (NP70), ∼100nm (NP100), ∼200nm (NP200), ∼400nm (NP400), ∼600nm (NP600) and ∼1000nm (NP1000) using facile fabrication methods based on a nanoprecipitation and solvent evaporation techniques. The nanoparticles showed a narrow size distribution with high yield. Then the size-controlled biodegradable nanoparticles were used to investigate how particle size at nanoscale affects interactions with tumor cells and macrophages. Interestingly, an opposite size-dependent interaction was observed in the two cells. As particle size gets smaller, cellular uptake increased in tumor cells and decreased in macrophages. We also found that paclitaxel (PTX)-loaded nanoparticles showed a size-dependent inhibition of tumor cell growth and the size-dependency was influenced by cellular uptake and PTX release. The size-controlled biodegradable nanoparticles described in this study would provide a useful means to further elucidate roles of particle size on various biomedical applications.

Antiproliferative effect of ASC-J9 delivered by PLGA nanoparticles against estrogen-dependent breast cancer cells.

Among polymeric nanoparticles designed for cancer therapy, PLGA nanoparticles have become one of the most popular polymeric devices for chemotherapeutic-based nanoformulations against several kinds of malignant diseases. Promising properties, including long-circulation time, enhanced tumor localization, interference with "multidrug" resistance effects, and environmental biodegradability, often result in an improvement of the drug bioavailability and effectiveness. In the present work, we have synthesized 1,7-bis(3,4-dimethoxyphenyl)-5-hydroxyhepta-1,4,6-trien-3-one (ASC-J9) and developed uniform ASC-J9-loaded PLGA nanoparticles of about 120 nm, which have been prepared by a single-emulsion process. Structural and morphological features of the nanoformulation were analyzed, followed by an accurate evaluation of the in vitro drug release kinetics, which exhibited Fickian law diffusion over 10 days. The intracellular degradation of ASC-J9-bearing nanoparticles within estrogen-dependent MCF-7 breast cancer cells was correlated to a time- and dose-dependent activity of the released drug. A cellular growth inhibition associated with a specific cell cycle G2/M blocking effect caused by ASC-J9 release inside the cytosol allowed us to put forward a hypothesis on the action mechanism of this nanosystem, which led to the final cell apoptosis. Our study was accomplished using Annexin V-based cell death analysis, MTT assessment of proliferation, radical scavenging activity, and intracellular ROS evaluation. Moreover, the intracellular localization of nanoformulated ASC-J9 was confirmed by a Raman optical imaging experiment designed ad hoc. PLGA nanoparticles and ASC-J9 proved also to be safe for a healthy embryo fibroblast cell line (3T3-L1), suggesting a possible clinical translation of this potential nanochemotherapeutic to expand the inherently poor bioavailability of hydrophobic ASC-J9 that could be proposed for the treatment of malignant breast cancer.

Loss of SNAIL inhibits cellular growth and metabolism through the miR-128-mediated RPS6KB1/HIF-1α/PKM2 signaling pathway in prostate cancer cells.

SNAIL is a promising target for the treatment of cancer because it is known to promote epithelial-mesenchymal transition. Recent studies suggest that SNAIL also takes part in metabolic reprogramming and chemotherapy resistance in some cancers. In prostate cancer (PCa), SNAIL has been proved to be required for hypoxia-induced invasion and as a potential marker for predicting the recurrence. However, the role of SNAIL in PCa aberrant metabolism is poorly understood. In this study, we identified that SNAIL regulated cellular growth and energy metabolism through the miR-128-mediated ribosomal protein S6 kinase 1 (RPS6KB1)/HIF-1α/PKM2 signaling pathway which played a key role in the reprogramming of cancer metabolism. Using quantitative RT-PCR (qRT-PCR), we found that SNAIL expression was elevated in castration-resistant prostate cancer tissues compared with androgen-dependent prostate cancer tissues and nontumorous tissues. Depletion of SNAIL increased miR-128 expression levels, inhibited cell growth, reduced glucose consumption and lactate production, and repressed the expression of RPS6KB1, HIF-1α, and PKM2 in PCa cells. Luciferase reporter assays showed the SNAIL regulated miR-128 expression at the transcriptional level and miR-128 modulated RPS6KB1 expression at the translational level. Furthermore, down-expression of miR-128 partially restored the effect of si-SNAIL on the suppression of cellular growth, metabolism, and RPS6KB1/HIF-1α/PKM2 signaling pathway. To our knowledge, it is the first time to demonstrate that SNAIL/miR-128/RPS6KB1 pathway plays a critical role in the progression of PCa.

Gadolinium-functionalized nanographene oxide for combined drug and microRNA delivery and magnetic resonance imaging

The delivery of anti-cancer therapeutics to tumors at clinically effective concentrations, while avoiding nonspecific toxicity, remains a major challenge for cancer treatment. Here we present nanoparticles of poly(amidoamine) dendrimer-grafted gadolinium-functionalized nanographene oxide (Gd-NGO) as effective carriers to deliver both chemotherapeutic drugs and highly specific gene-targeting agents such as microRNAs (miRNAs) to cancer cells. The positively charged surface of Gd-NGO was capable of simultaneous adsorption of the anti-cancer drug epirubicin (EPI) and interaction with negatively charged Let-7g miRNA. Using human glioblastoma (U87) cells as a model, we found that this conjugate of Let-7g and EPI (Gd-NGO/Let-7g/EPI) not only exhibited considerably higher transfection efficiency, but also induced better inhibition of cancer cell growth than Gd-NGO/Let-7g or Gd-NGO/EPI. The concentration of Gd-NGO/Let-7g/EPI required for 50% inhibition of cellular growth (IC50) was significantly reduced (to the equivalent of 1.3 μg/mL EPI) compared to Gd-NGO/EPI (3.4 μg/mL EPI). In addition, Gd-NGO/Let-7g/EPI could be used as a contrast agent for magnetic resonance imaging to identify the location and extent of blood–brain barrier opening and quantitate drug delivery to tumor tissues. These results suggest that Gd-NGO/Let-7g/EPI may be a promising non-viral vector for chemogene therapy and molecular imaging diagnosis in future clinical applications.

Epigallocatechin‐3‐gallate sensitizes therapeutic efficacy of doxorubicin involving autophagy inhibition in hepatoma Hep3B cells (655.2)

The green tea component (‐)‐Epigallocatechin‐3‐O‐gallate(EGCG), has promisingly been found to enhance the efficacy of several chemotherapy agents in hepatocellular carcinoma (HCC) treatment and its detailed mechanisms remain unclear. Herein, this study aimed to confirm the synergistic interaction of EGCG and DOX on Hep3B cells and to define whether the autophagic flux is involved in this cooperated fashion. Firstly, by MTT and trypan blue assay, both EGCG and DOX exhibited cellular growth inhibition and cell death induction effects. However, by western blotting and real time RT‐PCR, DOX dramatically induced the expression of Atg5 and beclin1, the autophagic signaling molecules, whereas EGCG presented a markedly and dose‐dependently inhibitory role in autophagy signaling. Secondly, EGCG and DOX combined treatment amazingly caused a synergistic effect of about 50% increment on cell death and about 45% augmentation on apoptosis versus monotherapy pattern. Interestingly, the DOX‐induced autophagy was abolished by this combination therapy. Thirdly, the anticancer effect of either DOX or combination with EGCG treatment was substantially impaired by either rapamycin, an autophagic agonist, or Atg5 as well as beclin1 siRNAs. Consistently, significantly tumor growth reduction and apoptosis increment were found in combination therapy compared with DOX alone in vitro study. And immunohistochemisty analysis indicated that the suppressed tendency of autophagic hallmark LC3 expression was consistent with thus combined usage in vitro. Taken together, the current study suggested that EGCG emerges as a chemotherapeutic augmenter and synergistically enhances DOX anticancer effects involving autophagy inhibition in HCC.Grant Funding Source: Supported by NSFC Grants 881172260, 30630145, 81360077 to G.Z. &amp; 81102495 to L.C.

Highlights of This Issue

Despite the clinical success of selective BRAF-targeted agents in melanoma, strategies to counteract the invariable development of resistance are not yet established. Acquaviva and colleagues show that HSP90 inhibition using the investigational drug ganetespib resulted in superior cytotoxic activity and antitumor efficacy over targeted BRAF or MEK inhibitors in preclinical models of mutant BRAF-driven melanoma. Importantly, ganetespib treatment readily overcame mechanisms of intrinsic and acquired resistance to vemurafenib, and dual targeting of BRAFV600E or MEK with ganetespib afforded combinatorial benefit in vitro and in vivo. Thus, HSP90 blockade may represent an alternative, and potentially complementary strategy, for therapeutic intervention in mutant-BRAF disease.An oncogenic fusion protein, EML4-ALK is involved in the pathogenesis of a subset of non–small cell lung cancer (NSCLC). The ALK/MET inhibitor crizotinib has already shown efficacy in ALK-driven NSCLC patients, but the treatment is not curative with rapid acquisition of resistance. In this report, Mori and colleagues have demonstrated that ASP3026, a novel small-molecule ALK inhibitor, induced tumor regression and prolonged survival in mice with ALK-driven NSCLC tumors, for which crizotinib showed limited efficacy, including the L1196M ‘gatekeeper’ mutant. These findings highlight the therapeutic potential of ASP3026 against cancer in patients with ALK abnormality.Although inhibition of IGF-1R was expected to eliminate a key resistance mechanism to anticancer therapies, clinical results to date have been disappointing. Fitzgerald and colleagues show that adaptive ErbB3 signaling is a key factor limiting the utility of anti-IGF-1R agents. The authors describe a novel bispecific tetravalent antibody, MM-141, that co-blocks IGF and heregulin-induced signaling and induces degradation of receptor complexes containing IGF-1R and ErbB3, including their heterodimers with insulin receptor and ErbB2. MM-141 shows superior cellular and xenograft growth inhibition to antibody monotherapies and potentiates the effect of mTOR inhibitors and taxanes, supporting its ongoing clinical development.It is challenging to predict patients' responses to cancer treatment and mTOR inhibitors are no exception. Wang and colleagues used androgen receptor (AR) expression as a marker to evaluate breast cancers' sensitivity to NVP-BEZ235, an experimental mTOR inhibitor, and investigated the beneficial effect of combining NVP-BEZ235 with dihydrotestosterone (DHT), an unaromatizable androgen. AR-positive breast cancer cell lines are more sensitive to NVP-BEZ235 compared with AR-negative cells. DHT/NVP-BEZ235 combination achieved therapeutic effects superior to either drug alone and reversed therapy-induced side effects. It suggests that AR expression may be used to predict NVP-BEZ235 response and AR induction could benefit NVP-BEZ235 treatment for breast carcinomas.

Autophagy Inhibition Contributes to the Synergistic Interaction between EGCG and Doxorubicin to Kill the Hepatoma Hep3B Cells

(-)-Epigallocatechin-3-O-gallate(EGCG), the highest catechins from green tea, has promisingly been found to sensitize the efficacy of several chemotherapy agents like doxorubicin (DOX) in hepatocellular carcinoma (HCC) treatment. However, the detailed mechanisms by which EGCG augments the chemotherapeutic efficacy remain unclear. Herein, this study was designed to determine the synergistic impacts of EGCG and DOX on hepatoma cells and particularly to reveal whether the autophagic flux is involved in this combination strategy for the HCC. Electron microscopy and fluorescent microscopy confirmed that DOX significantly increased autophagic vesicles in hepatoma Hep3B cells. Western blot and trypan blue assay showed that the increasing autophagy flux by DOX impaired about 45% of DOX-induced cell death in these cells. Conversely, both qRT-PCR and western blotting showed that EGCG played dose-dependently inhibitory role in autophagy signaling, and that markedly promoted cellular growth inhibition. Amazingly, the combined treatment caused a synergistic effect with 40 to 60% increment on cell death and about 45% augmentation on apoptosis versus monotherapy pattern. The DOX-induced autophagy was abolished by this combination therapy. Rapamycin, an autophagic agonist, substantially impaired the anticancer effect of either DOX or combination with EGCG treatment. On the other hand, using small interference RNA targeting chloroquine autophagy-related gene Atg5 and beclin1 to inhibit autophagy signal, hepatoma cell death was dramatically enhanced. Furthermore, in the established subcutaneous Hep3B cells xenograft tumor model, about 25% reduction in tumor growth as well as 50% increment of apoptotic cells were found in combination therapy compared with DOX alone. In addition, immunohistochemistry analysis indicated that the suppressed tendency of autophagic hallmark microtubule-associated protein light chain 3 (LC3) expressions was consistent with thus combined usage in vitro. Taken together, the current study suggested that EGCG emerges as a chemotherapeutic augmenter and synergistically enhances DOX anticancer effects involving autophagy inhibition in HCC.

Co-targeting the MAPK and PI3K/AKT/mTOR pathways in two genetically engineered mouse models of schwann cell tumors reduces tumor grade and multiplicity.

Malignant peripheral nerve sheath tumors (MPNSTs) are soft tissue sarcomas that occur spontaneously, or from benign plexiform neurofibromas, in the context of the genetic disorder Neurofibromatosis Type 1 (NF1). The current standard treatment includes surgical resection, high-dose chemotherapy, and/or radiation. To date, most targeted therapies have failed to demonstrate effectiveness against plexiform neurofibromas and MPNSTs. Recently, several studies suggested that the mTOR and MAPK pathways are involved in the formation and progression of MPNSTs. Everolimus (RAD001) inhibits the mTOR and is currently FDA approved for several types of solid tumors. PD-0325901 (PD-901) inhibits MEK, a component of the MAPK pathway, and is currently in clinical trials. Here, we show in vitro than MPNST cell lines are more sensitive to inhibition of cellular growth by Everolimus and PD-901 than immortalized human Schwann cells. In combination, these drugs synergistically inhibit cell growth and induce apoptosis. In two genetically engineered mouse models of MPNST formation, modeling both sporadic and NF1-associated MPNSTs, Everolimus, or PD-901 treatment alone each transiently reduced tumor burden and size, and extended lifespan. However, prolonged treatment of each single agent resulted in the development of resistance and reactivation of target pathways. Combination therapy using Everolimus and PD-901 had synergistic effects on reducing tumor burden and size, and increased lifespan. Combination therapy allowed persistent and prolonged reduction in signaling through both pathways. These data suggest that co-targeting mTOR and MEK may be effective in patients with sporadic or NF1-associated MPNSTs.

Facile synthesis of a novel mono-organoimido functionalized polyoxometalate cluster [(n-C4H9)4N]2[Mo6O18([tbnd]NAr)] (Ar = p-C2H5C6H4): Crystal structure, spectral characterization and initial antitumor activity

A novel mono-functionalized arylimido derivative of hexamolybdate bearing the electron-donating ethyl group, [Bu4N]2[Mo6O18(NAr)], has been synthesized by an improved reaction of octamolybdate ion with 4-ethylaniline hydrochloride using DCC (N,N′-dicyclohexylcarbodi-imide) as the dehydrating agent. Detailed assignments were achieved for the title compound by elemental analysis, IR, 1H NMR, UV–visible and single-crystal X-ray diffraction analysis. Preliminary antitumor activity test showed that the title compound has some effects on the cellular growth inhibition to K562 cells.