Activity In Cancer Cells Research Articles

Stress and its molecular consequences in cancer progression.

Stress, caused by psychological, physiological and physical factors has an adverse impact on human body homeostasis. There are two kind of stress: short-term and chronic. Cancer patients usually live under chronic stress, caused by diagnosis-related strong emotional experience and depression, resulting from various difficulties associated with disease progression and treatment. At the molecular level, stress factors induce production and secretion of stress-related hormones, such as catecholamines, glucocorticoids and dopamine (as a part of adaptational body response), which influence both normal and transformed cells through their specific receptors. The particular effects exerted by these molecules on cancer cells have been also observed in in vitro cultures and include changes in proliferation, apoptosis susceptibility and migration/invasion potential. As a result, it has been suggested that stress hormones may be responsible for progression of malignancy and thus accelerate the metastasis formation in cancer patients. However, the clinical data on correlation between stress and the patients survival, as well as the molecular analysis of stress hormone receptors expression and action in cancer cell, have not yet provided an unequivocal answer. For this reason, extensive studies, on molecular and clinical level are needed to fully determine stress impact on cancer progression and on the effectiveness of anti-cancer treatment. Nowadays, it seems reasonable that the personalization of anti-cancer therapy should also focus on mental state of cancer patients, and provide them with psychological tools or techniques for stress management.

Abstract BS3-2: The unfolded protein response: A protective pathway and therapeutic target in breast cancer

Abstract We identified BHPI, a potent first-in-class non-competitive estrogen receptor α (ERα) biomodulator that kills therapy-resistant ER positive cancer cells. In mouse xenografts, BHPI induced rapid and dramatic regression of breast cancers. We also demonstrated BHPI's effectiveness in cancer cells containing ER mutations Y537S and D538G that are common in metastatic breast cancer. We used the CRISPR-Cas9 genome editing system to isolate T47D breast cancer cell lines in which both copies of wild type ER are replaced with ERY537S or ERD538G. In anchorage independent 3-dimensional culture, the ERY537S and ERD538G cells exhibit robust proliferation in micromolar 4-hydroxytamoxifen and fulvestrant/Faslodex/ICI 182,780, but are killed by nanomolar BHPI. BHPI is so effective because it works by distorting a newly identified normal pathway of estrogen-ER action. BHPI hyperactivates the endoplasmic reticulum stress sensor, the unfolded protein response (UPR). Estrogen-ER rapidly elicits moderate and transient anticipatory activation of the UPR. Activation of this conserved pathway is critical for estrogen and epidermal growth factor (EGF) induced gene expression and cell proliferation and for VEGF regulated angiogenesis and cell survival. Moreover, in analysis of data from approximately 1,000 ER positive breast cancer patients, activation of a UPR gene signature at diagnosis was tightly correlated with subsequent tumor recurrence, tamoxifen resistance and a poor prognosis. A major mechanism by which tumors develop resistance to therapy is overexpression of pumps, such as multidrug resistance protein 1 (MDR1)/p-glycoprotein, that carry out ATP-dependent pumping of anticancer drugs out of tumor cells. Nontoxic small molecule inhibitors targeting MDR1 remain elusive. Instead, we used BHPI's novel action in cancer cells to target MDR1's substrate, ATP. Acting via ER, BHPI hyperactivates the anticipatory UPR pathway leading to an ATP-depleting futile cycle in which there is ATP-dependent pumping of calcium into the endoplasmic reticulum (EnR), but the EnR calcium channels opened by BHPI-ER action allow the calcium to leak back out. This futile cycle rapidly depletes intracellular ATP, inactivating MDR1 in multidrug resistant breast and ovarian cancer cells. BHPI restored sensitivity of multidrug resistant breast and ovarian cancer cells to killing by therapeutically relevant concentrations of several anticancer drugs. In an orthotopic ovarian cancer xenograft model using OVCAR-3 cells, that are highly resistant to diverse anticancer drugs, the taxane paclitaxel was ineffective and the paclitaxel-treated tumors were uniquely prone to metastasize to adjacent tissue. BHPI alone strongly reduced tumor growth. Notably, tumors were undetectable in mice treated with BHPI plus paclitaxel. Compared to control ovarian tumors, after the combination therapy, plasma levels of the cancer biomarker, CA125, were at least several hundred fold lower; moreover, CA125 levels progressively declined to undetectable. Targeting drug resistance in ER positive tumors through BHPI-mediated, UPR-dependent, ATP depletion represents a promising new therapeutic strategy. (Support: NIH RO1 DK 071909, DOD BCRP W81XWH-13) Citation Format: Shapiro DJ. The unfolded protein response: A protective pathway and therapeutic target in breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr BS3-2.

Novel Molecular Multilevel Targeted Antitumor Agents.

A multifunctional fusion protein, IL-13.E13K-D2-NLS, effectively recognizes glioblastoma (GBM) cells and delivers its portion to the cell nucleus. IL-13.E13K-D2-NLS is composed of a cancer cell targeting ligand (IL-13.E13K), specialized cytosol translocation bacterial toxin domain 2 of Pseudomonas exotoxin A (D2) and SV40 T antigen nuclear localization signal (NLS). We have now tested whether we can produce proteins that would serve as a delivery vehicle to lysosomes and mitochondria as well. Moreover, we examined whether IL-13.E13K-D2-NLS can deliver anti-cancer drugs like doxorubicin to their nuclear site of action in cancer cells. We have thus constructed two novel proteins: IL-13.E13K-D2-LLS which incorporates lysosomal localization signal (LLS) of a human lysosomal associated membrane protein (LAMP-1) for targeting to lysosomes and IL-13-D2-KK2, which incorporates a pro-apoptotic peptide (KLAKLAK)2 (KK2) exerting its action in mitochondria. Furthermore, we have produced IL-13.E13K-D2-NLS and IL-13.E13K-D2-LLS versions containing a cysteine for site-specific conjugation with a modified doxorubicin, WP936. We found that single-chain recombinant proteins IL-13.E13K-D2-LLS and IL-13-D2-KK2 are internalized and localized mostly to the lysosomal and mitochondrial compartments, respectively, without major trafficking to cells' nuclei. We also determined that IL-13.E13K-D2-NLS-cys[WP936], IL-13.E13K-D2-LAMP-cys[WP936] and IL-13-D2-KK2 were cytotoxic to GBM cells overexpressing IL-13RA2, while much less cytotoxic to GBM cell lines expressing low levels of the receptor. IL-13.E13K-D2-NLS-cys[WP936] was the most potent of the tested anti-tumor agents including free WP936. We believe that our receptor-directed intracellular organelle-targeted proteins can be employed for numerous specific and safer treatment applications when drugs have specific intracellular sites of their action.

Abstract 4635: Comparative cancer cell line profiling differentiates the mechanism of action of different PI3K/mTOR, Aurora kinase and EZH2 inhibitors

Abstract [purpose] Profiling of drug candidates in cell line panels is an important tool to compare the selectivity and targeting of new anti-cancer agents. In addition, comparative profiling may be used to repurpose established therapeutics by identifying new mechanisms of action or cross-selectivities. [experimental procedures] A collection of more than 120 anti-cancer agents, targeting all important oncogenic signaling pathways, including classic cytotoxic agents as well as many targeted kinase inhibitors and epigenetic modulators, was profiled on a panel of 44 or 66 parallel cell line proliferation assays (Oncolines™) [1,2]. The Oncolines™ profiles of the compounds were compared by Pearson correlations of their inhibitor responses. Inhibitor sets were clustered using hierarchical trees. Response profiles were correlated to the genetic background of the cell lines by Analysis of Variance (Anova). [results] Reproducibility of the NTRC Oncolines™ cell panel was validated by monitoring cell growth rate and the variation in IC50s of replicate profiles over a period of three years. The Pearson correlation between replicates ranged between 0.60 and 0.99 for 16 different inhibitors, depending on dose-response curve shape. Correlation analyses of the > 120 profiled anti-cancer agents revealed separate clusters of, a.o., taxanes, platins, topo-isomerase inhibitors, and EGFR, ABL, MEK and BRAF inhibitors. This demonstrates that the Oncolines™ profiles are an unbiased representation of the compound's mechanisms. The profile of the BTK inhibitor ibrutinib correlated with EGFR inhibitors. In biochemical experiments we showed that this due to its cross-reactivity with EGFR. The six Aurora kinase inhibitors profiled fall into two separate clusters, which are related to their biochemical selectivity. Thus, Aurora A-selective inhibitors are relatively more active in cell lines with mutations in cell cycle checkpoint-related genes such as TP53 and RB1; whereas pan-Aurora inhibitors are more active in cell lines with mutations in growth factor signaling pathways, such as NRAS. Profiling of eleven PI3 kinase and mTOR inhibitors revealed four distinct clusters. PI3Kalpha and PI3Kdelta isoform selective inhibitors each target genetically distinct subgroups of cell lines. Rapamycin-analogs, such as everolimus, specifically target PTEN-mutant cell lines. Finally, profiling of EZH2 inhibitors indicates that there are essentially two classes and that these have a cellular profile that is distinct from HDAC, DOT1L or BET inhibitors. [conclusions] Comparative cancer cell line profiling is a powerful tool to rapidly explore the pharmacogenomics of drug action in cancer cells and to identify new or previously unnoted activities of compounds. [references]: [1] Uitdehaag et al. (2014) PLOS ONE 9(3) e92146; [2] Uitdehaag et al. (2015) PLOS ONE 10(6) e0132230. Citation Format: Joost C.M. Uitdehaag, Jeroen A.D.M. de Roos, Martine B.W. Prinsen, Judith R.F. de Vetter, Jelle Dylus, Antoon M. van Doornmalen, Suzanne J.C. van Gerwen, Jos de Man, Rogier C. Buijsman, Guido J.R. Zaman. Comparative cancer cell line profiling differentiates the mechanism of action of different PI3K/mTOR, Aurora kinase and EZH2 inhibitors. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4635.

Apoptosis-Inducing Effects of Amaryllidaceae Alkaloids.

The Amaryllidaceae occupies a privileged status amongst medicinal plants in having delivered the Alzheimer's drug galanthamine to the clinical market. Following its resounding success, there have been several positive indicators for the emergence of an anticancer drug from the family due to the potent antiproliferative activities manifested by several of its alkaloid constituents. Of these, the phenanthridones such as pancratistatin hold most promise as potential chemotherapeutics having succumbed to various phases of clinical trials. Other cytotoxic targets of the Amaryllidaceae are to be found within the lycorane and crinane groups, as exemplified by crinine and lycorine. Although the molecular targets of these alkaloids still remain elusive, much effort has gone into understanding their mode of action in cancer cells. Recent findings have shown that the apoptotic pathway may be a key factor in cancer cell death instigated by Amaryllidaceae alkaloids. As such, this review seeks to: (a) examine the apoptotic effects of Amaryllidaceae alkaloids in cancer cells; (b) explore the molecular basis to these effects; and (c) provide a pharmacophoric rationale in support of these activities.

Horner-Wadsworth-Emmons approach to piperlongumine analogues with potent anti-cancer activity.

Natural products with anti-cancer activity play a vital role in lead and target discovery. We report here the synthesis and biological evaluation of the plant-derived alkaloid, piperlongumine and analogues. Using a Horner-Wadsworth-Emmons coupling approach, a selection of piperlongumine-like compounds were prepared in good overall yield from a novel phosphonoacetamide reagent. A number of the compounds displayed potent anti-cancer activity against colorectal (HCT 116) and ovarian (IGROV-1) carcinoma cell lines, via a mechanism of action which may involve ROS generation. Contrary to previous reports, no selective action in cancer cell (MRC-5) was observed for piperlongumine analogues.

The disulfide compound α-lipoic acid and its derivatives: A novel class of anticancer agents targeting mitochondria

The endogenous disulfide α-lipoic acid (LA) is an essential mitochondrial co-factor. In addition, LA and its reduced counterpart dihydro lipoic acid form a potent redox couple with antioxidative functions, for which it is used as dietary supplement and therapeutic. Recently, it has gained attention due to its cytotoxic effects in cancer cells, which is the key aspect of this review. We initially recapitulate the dietary occurrence, gastrointestinal absorption and pharmacokinetics of LA, illustrating its diverse antioxidative mechanisms. We then focus on its mode of action in cancer cells, in which it triggers primarily the mitochondrial pathway of apoptosis, whereas non-transformed primary cells are hardly affected. Furthermore, LA impairs oncogenic signaling and displays anti-metastatic potential. Novel LA derivatives such as CPI-613, which target mitochondrial energy metabolism, are described and recent pre-clinical studies are presented, which demonstrate that LA and its derivatives exert antitumor activity in vivo. Finally, we highlight clinical studies currently performed with the LA analog CPI-613. In summary, LA and its derivatives are promising candidates to complement the arsenal of established anticancer drugs due to their mitochondria-targeted mode of action and non-genotoxic properties.

Human telomerase inhibitors from microbial source.

Telomerase enzyme inhibitors have gained attention of scientific field due to the specificity of action of telomerase based therapies. Some telomerase have good combinatorial action with certain DNA damaging drugs. Natural compounds isolated from microbes provide a new scope of screening and large scale production of telomerase inhibitors. This review emphasizes the biochemistry and mode of action of different types of telomerase inhibitors isolated from microbial sources. Also elaborates on classification of telomerase inhibitors based on their mode of action in cancer cells.

Anticancer activity of galactoxyloglucan polysaccharide-conjugated doxorubicin nanoparticles: Mechanistic insights and interactome analysis

Toxicity associated with chemotherapeutic drugs such as doxorubicin (Dox), is one of the major obstacles that is currently affecting patients. PST-Dox (Galactoxyloglucan, PST001-conjugated Dox) nanoparticles were synthesized by encapsulating Dox with polysaccharide PST001, isolated from Tamarindus indica (Ti) by ionic gelation with tripolyphosphate (TPP). Herein, we demonstrate a detailed mechanistic and interactome network analysis that is specific to PST-Dox action in cancer cells and normal lymphocytes. Our results show that PST-Dox is superior to its parental counterparts, exhibiting a greater cytotoxicity by the induction of apoptosis against a wide variety of cancers by enhanced cellular uptake of Dox from the nanoparticle conjugates. Also, PST-Dox nanoparticles were non-toxic to normal lymphocytes with limited immunostimulatory effects up to certain doses. Elucidation of molecular mechanism by whole genome microarray in cancer cells and lymphocytes revealed that a large number of genes were dysregulated specifically in cancer cells. Specifically, a unique target gene EGR1, contextually determined translational activation of P53 in the cancerous and non-cancerous cells. Most of the key downregulated genes were tyrosine kinases, indicating the potential inhibitory action of PST-Dox on tyrosine kinase oncogenic pathways. Western blotting of proteins corresponding to the genes that were altered at the genomic level was very well correlated in the majority of them, except in a few that demonstrated post-transcriptional modifications. The important findings and highly disciplined approaches highlighted in the present study will speed up the therapeutic potential of this augmented nanoparticle formulation for more robust clinical studies and testing in several cancers.

Artemisinin–Second Career as Anticancer Drug?

Artemisinin represents a showcase example not only for the activity of medicinal herbs deriving from traditional chinese medicine, but for phytotherapy in general. Its isolation from Sweet Wormwood (qinhao, Artemisia annua L.) represents the starting point for an unprecedent success story in the treatment of malaria worldwide. Beyond the therapeutic value against Plasmodium parasites, it turned out in recent years that the bioactivity of artemisinin is not restricted to malaria. We and others found that this sesquiterpenoid also exerts profound anticancer activity in vitro and in vivo. Artemisinin-type drugs exert multi-factorial cellular and molecular actions in cancer cells. Ferrous iron reacts with artemisinin, which leads to the formation of reactive oxygen species and ultimately to a plethora anticancer effects of artemisinins, e.g. expression of antioxidant response genes, cell cycle arrest (G1 as well as G2 phase arrests), DNA damage that is repaird by base excision repair, homogous recombination and non-homologous end-joining, as well as different modes of cell death (intrinsic and extrinsic apoptosis, autophagy, necrosis, necroptosis, oncosis, and ferroptosis). Furthermore, artemisinins inhibit neoangiogenesis in tumors. The signaling of major transcription factors (NF-κB, MYC/MAX, AP-1, CREBP, mTOR etc.) and signaling pathways are affected by artemisinins (e.g. Wnt/β-catenin pathway, AMPK pathway, metastatic pathways, nitric oxide signaling, and others). Several case reports on the compassionate use of artemisinins as well as clinical Phase I/II pilot studies indicate the clinical activity of artemisinins in veterinary and human cancer patients. Larger scale of Phase II and III clinical studies are required now to further develop artemisinin-type compounds as novel anticancer drugs. Abbreviations: ABCB6, ATP-binding Cassette Transporter B6; ABCG2, ATP Binding Cassette Transporter G2; AIF, Apoptosis Inducing Factor; AKT, V-Akt Murine Thymoma Viral Oncogene Homologue; AMPK, AMP-Activated Protein Kinase; Ang-1, Angiotensin 1; ARE, Arteether; ARM, Artemether; ARS, Artemisinin; ART, Artesunate; ATF4, Activating Transcription Factor 4; Bak, Bcl2 Antagonist/Killer 1; Bax, Bcl2-Associated X Protein, Pro-Apoptotic BH3-Only Bcl-2 Family Member; Bcl-2, B-cell CLL/lymphoma 2; Bcl-xL, B-cell CLL/Lymphoma-x Long; BCR/ABL, Breakpoint Cluster Region/Abl Proto-Oncogene; Bid, BH3-Interacting Domain Death Agonist; Bim, Pro-Apoptotic Bcl2- Family Member; BSO, Buthionine Sulfoximine; C/EBP β, CCAAT/Enhancer Binding Protein β; CAM, Chorioallantoic Membrane; CD, Cluster of Differentiation; CDC25B; CDK, Cyclin-Dependent Kinase; CHOP/DDIT, DNA Damage-Inducible Transcript; CIP1/WAF1, CDK-Interacting Protein 1/Wild-Type p53-Activated Fragment 1; c-JUN, Jun Proto-Oncogene; COX2, Cyclooxygenase 2; CREB, Cyclic ATP Responsive Element Binding Protein; DHA, Dihydroartesunate; DNA-PK, DNA-Dependent Protein Kinase; DR5, Death Receptor 5; E2F1, E2F Transcription Factor 1; EA, Ethacrynic Acid; EGFR, Epidermal Growth Factor Receptor; EMT, Epithelial to Mesenchymal Transition; EndoG, Endonuclease G; ERK, Extracellular Signal-Regulated Kinase; FAK, Focal Adhesion Kinase; FAS, Fas Cell Surface Death Receptor; Flt-1, Fms- Related Tyrosine Kinase 1; GADD153, Growth Arrest and DNA Damage-Inducible 153; GRP78, Glucose-Regulated Protein; GSK3 β, Glycogen Synthase Kinase 3 β; HIF-1α, Hypoxia-Inducible Factor-1 α; HPV39, Human Papilloma Virus 39; HR, Homologous Repair; hTERT, Human Telomerase Reverse Transcriptase; hTR, Human Telomerase; HUVEC, Human Umbilical Vein Endothelial Cells; IFN, Interferon; IL, Interleukin; IκBβ, Inhibitor of Kappa B β; JNK, c-Jun N-Terminal Kinase; KDR/flk-1, Kinase Insert Domain Receptor; LC3, Microtubule- Associated Protein 1 Light Chain 3; MAPK, Nitogen-Activated Protein Kinase; MAX, MYC-Associated Factor X; Mcl-1, Myeloid Cell Leukemia 1; MDM2, Mouse Double Minute 2 Homologue; MEK, also known as MAPKK, Mitogen-Activated Protein Kinase Kinase; MMP, Matrix Metalloproteinase; MPNST, Malignant Peripheral Nerve Sheath Tumor; mTOR, Mammalian Target of Rapamycin; MYC, Avian Myelomastosis Viral Oncogene Homologue; NAC, N-Acetyl Cysteine; NFκB, Nuclear Factor Kappa B; NHEJ, Non-Homologous End-Joining; NO, Nitric Oxide; NOXA, Also Known As PMA/P1; Phorbol-12-Myristate-13-Acetate-Induced Protein 1; PARK7, Parkinson Disease Protein 7, Protein Deglycase DJ-1; PARP, Poly ADP Ribose Polymerase; PCNA, Proliferating Cell Nuclear Antigen; PGE2, Prostaglandine E2; PI3-K, Phospoinositide-3 Kinase; PMA, Phorbol-12-Myristate-13-Acetate; RAF, Ras-Associated Factor Proto-Oncogene; RAS, Rat Sarcoma Viral Oncogene Homologue; RKIP, Raf-1 Kinase Inhibitor Protein; ROS, Reactive Oxygen Species, SMAC/DIABLO, IAP-Binding Mitochondrial Protein; TCTP, Translationally Controlled Tumor Protein; TF, Transferrin; TFRC, Transferrin Receptor 1 Gene; TGB1, Triple Gene Block Protein β, TGF-beta, Tumor Growth Factor β, TIMP, Tissue Inhibitor of Metalloproteinase, TNF-α, Tumor Necrosis Factor α, TOPO2 A, DNA Topoisomerase 2 α, TRAIL, Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand, Treg, Regulatory T Cells, VDAC2, Voltage-Dependent Anion Channel 2, VEGF, Vascular Endothelial Growth Factor, VEGFR, Vascular Endothelial Growth Factor Receptor, XIAP, X-Linked Inhibitor of Apoptosis, YY1, Yin Yang 1

Abstract 2889: Human antibodies induced by vaccination with a carbohydrate mimetic-peptide vaccine show functional anti-tumor activity on human lung-cancer cells

Abstract Introduction: Lung cancer is the most common cancer worldwide, and the leading cancer killer in both men and women in the United States. The 5-year survival rate for lung cancer ranges from <2% to about 70% depending on stage. Current treatment options including surgery, chemotherapy, and radiotherapy have limited efficacy, as over half of people with lung cancer die within a year of initial diagnosis. Tumor vaccines hold the potential to deliver durable, specific and systemic anti-tumor responses in lung-cancer patients diagnosed with advanced disease. Appearance of tumor-associated carbohydrate antigens (TACAs) is the hallmark of cancer initiation and metastasis in many cancer types, including lung cancer. We have developed active vaccination strategies that target TACAs using peptide mimetics, and successfully vaccinated stage IV breast-cancer patients. The purpose of the current study is to evaluate functionality of vaccine-induced antibodies against lung-cancer cells. Procedure: Patients with stage IV breast cancer underwent vaccination with the carbohydrate mimicking peptide P10s synthesized with the Pan T-cell peptide PADRE (P10s-PADRE). Doses of P10s-PADRE admixed with MONTANIDE™ ISA 51 VG were administered to subjects subcutaneously in rotating injection sites in the abdomen on weeks 1, 2, 3, 7 and 9. Pre-immune (week 1) and post-immune sera (weeks 4 and 7) were tested for functional activity against a non-Small Cell lung-cancer cell line (NCI-H522) and a Small Cell lung-cancer cell line (NCI-H69). Cell-surface carbohydrates were profiled and serum binding to cells was assayed by flow cytometry. Cytotoxicity, migration and invasion assays were performed to assess functional anti-lung cancer-cell activity of the sera. Results: Both cell lines express relevant TACAs that can be targeted with P10s-PADRE immunization. Vaccinated serum reacted with tumor cells, induced toxicity, and prevented tumor-cell migration and invasion in vitro. Conclusion: Our results show that P10s-PADRE vaccination of breast-cancer patients induces functional immune activity against lung-cancer cells. Accordingly, we propose to extend our successful vaccination strategy to lung-cancer patients with advanced stage III/IV disease. This group of patients has poor survival, and induction of functional antibodies can significantly increase disease control and survival rate. Citation Format: Konstantinos Arnaoutakis, Fariba Jousheghany, Issam Makhoul, Laura Hutchins, Thomas Kieber-Emmons, Behjatolah Monzavi-Karbassi. Human antibodies induced by vaccination with a carbohydrate mimetic-peptide vaccine show functional anti-tumor activity on human lung-cancer cells. [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 2889. doi:10.1158/1538-7445.AM2014-2889

Histone deacetylase inhibitor (HDACI) mechanisms of action: emerging insights.

Initially regarded as "epigenetic modifiers" acting predominantly through chromatin remodeling via histone acetylation, HDACIs, alternatively referred to as lysine deacetylase or simply deacetylase inhibitors, have since been recognized to exert multiple cytotoxic actions in cancer cells, often through acetylation of non-histone proteins. Some well-recognized mechanisms of HDACI lethality include, in addition to relaxation of DNA and de-repression of gene transcription, interference with chaperone protein function, free radical generation, induction of DNA damage, up-regulation of endogenous inhibitors of cell cycle progression, e.g., p21, and promotion of apoptosis. Intriguingly, this class of agents is relatively selective for transformed cells, at least in pre-clinical studies. In recent years, additional mechanisms of action of these agents have been uncovered. For example, HDACIs interfere with multiple DNA repair processes, as well as disrupt cell cycle checkpoints, critical to the maintenance of genomic integrity in the face of diverse genotoxic insults. Despite their pre-clinical potential, the clinical use of HDACIs remains restricted to certain subsets of T-cell lymphoma. Currently, it appears likely that the ultimate role of these agents will lie in rational combinations, only a few of which have been pursued in the clinic to date. This review focuses on relatively recently identified mechanisms of action of HDACIs, with particular emphasis on those that relate to the DNA damage response (DDR), and discusses synergistic strategies combining HDACIs with several novel targeted agents that disrupt the DDR or antagonize anti-apoptotic proteins that could have implications for the future use of HDACIs in patients with cancer.

Cytotoxic neviotane triterpene-type from the red sea sponge Siphonochalina siphonella.

Background:Siphonochalina siphonella is a marine sponge collected from saudi Red Sea water and scare study from this region.Objective:To isolate the anticancer triterpenes with potent cytotoxicity from marine sponge, Siphonochalina siphonella and state the mode of action in cancer cell lines.Materials and Methods:The sponge material was collected, extracted with organic solvent, and fractionated on different adsorbents. The structure of the pure metabolites were elucidated employing different spectroscopic techniques including 1D (1H and 13C) and 2D (COSY, HMQC and HMBC) NMR, and MS spectroscopy.Results:A new Neviotine-C (1) was obtained, along with four known metabolites (2-5). All compounds, except 5, were tested towards MCF-7, PC-3 and A549 and showed effects with IC50 in range 7.9-87 μM, whilst, 3 showed potent anti-proliferative activity against PC-3 and A549 with IC50 = 7.9 ± 0.120 and 8.9 ± 0.010 μM, respectively.Conclusion:Compounds (1-4) showed significant cytotoxic activities, while 3 showed potent effect. The antiproliferative of 3 was attributed to significant S-phase cell cycle arrest.

Manganoporphyrins Increase Ascorbate-Induced Cytotoxicity by Enhancing H2O2 Generation

Renewed interest in using pharmacological ascorbate (AscH-) to treat cancer has prompted interest in leveraging its cytotoxic mechanism of action. A central feature of AscH- action in cancer cells is its ability to act as an electron donor to O2 for generating H2O2. We hypothesized that catalytic manganoporphyrins (MnP) would increase AscH- oxidation rates, thereby increasing H2O2 fluxes and cytotoxicity. Three different MnPs were tested (MnTBAP, MnT2EPyP, and MnT4MPyP), exhibiting a range of physicochemical and thermodynamic properties. Of the MnPs tested, MnT4MPyP exerted the greatest effect on increasing the rate of AscH- oxidation as determined by the concentration of ascorbate radical [Asc•-] and the rate of oxygen consumption. At concentrations that had minimal effects alone, combining MnPs and AscH- synergized to decrease clonogenic survival in human pancreatic cancer cells. This cytotoxic effect was reversed by catalase, but not superoxide dismutase, consistent with a mechanism mediated by H2O2. MnPs increased steady-state concentrations of Asc•- upon ex vivo addition to whole blood obtained either from mice infused with AscH- or patients treated with pharmacologic AscH-. Finally, tumor growth in vivo was inhibited more effectively by combining MnT4MPyP with AscH-. We concluded that MnPs increase the rate of oxidation of AscH- to leverage H2O2 flux and ascorbate-induced cytotoxicity.

The anticancer activity of alpha-tomatine against mammary adenocarcinoma in mice

To evaluate the anticancer effect of alpha-tomatine (i.p.) either alone or in combination with doxorubicin (i.v.) in a mouse tumour model. We studied the effect of repeated alpha-tomatine (0.1 - 9 mg/kg) and/or doxorubicin (2 mg/kg) on the growth and mitotic activity of the solid Ehrlich tumour in vivo, as well as on the survival of the tumour-bearing mice. Monotherapy with alpha-tomatine had a significant dose-dependent anticancer effect which peaked at 1mg/kg. This was shown by both slowed tumour growth and reduced tumour cell proliferation. We also provide the first evidence that the combination alpha-tomatine (1 mg/kg) and doxorubicin (2 mg/kg) had a synergistic effect and significantly prolonged the survival of the mice. Neither alpha-tomatine nor doxorubicin influenced the infiltration of tumours with CD3+ lymphocytes; nor were we able to find an in vivo modulation of the key molecules of two regulatory pathways reported in vitro as the principal anti-cancer mechanisms of alpha-tomatine, i.e. iNOS and phosphorylated ERK2. However, alpha-tomatine still led to intracellular DNA inhibition and protein synthesis in Ehrlich tumour cells in a short-term culture ex vivo with IC50 values of 8.7 and 6.6 µM. The results suggest that ΤΟΜ, especially in combination with doxorubicin, may be a promising agent for the treatment of malignant solid tumours. Despite growing knowledge of the mechanisms of ΤΟΜ action in cancer cells, most aspects remain unclear. Parallel organ toxicity, especially potential liver effects, requires careful attention when performing in vivo studies in the future.

IGFBP-2 nuclear translocation is mediated by a functional NLS sequence and is essential for its pro-tumorigenic actions in cancer cells

IGFBP-2 is highly expressed in both the serum and tumor tissues of most cancers, and is considered one of the most significant genes in the signature of major cancers. IGFBP-2 mainly modulates IGF actions in the pericellular space; however, there is considerable evidence to suggest that IGFBP-2 may also act independently of the IGFs. These IGF-independent actions of IGFBP-2 are exerted either via interactions at the cell surface or intracellularly, via interaction with cytoplasmic or nuclear-binding partners. The precise mechanism underlying the intracellular/intranuclear localization of IGFBP-2 remains unclear. In this study, we investigated IGFBP-2 nuclear localization in several common cancer cells with the aim of dissecting the mechanism of its nuclear trafficking. IGFBP-2 is detected in the nuclei of common cancer cells, including breast, prostate and several neuroblastoma cell lines, using cell fractionation and confocal microscopy. Via nuclear import assays, we show that nuclear entry of IGFBP-2 is mediated by the classical nuclear import mechanisms, primarily through importin-α, as demonstrated by the use of blocking, competition and co-immunoprecipitation assays. Bioinformatics analysis of the IGFBP-2 protein sequence with PSORT II identified a classical nuclear localization signal (cNLS) sequence at 179PKKLRPP185, within the IGFBP-2 linker domain, mutagenesis of which abolishes IGFBP-2 nuclear import. Accordingly, the NLSmutIGFBP-2 fails to activate the VEGF promoter, which would otherwise occur in the presence of wild-type IGFBP-2. As a consequence, no activation of angiogenic processes were observed in NLSmutIGFBP-2 expressing SHEP cells when implanted onto our in vivo quail chorio-allantoic membrane model. Taken together, these data show for the first time that IGFBP-2 possesses a functional NLS sequence and that IGFBP-2 actively translocates into the nucleus by a classical nuclear import mechanism, involving formation of IGFBP-2 complexes with importin-α. Nuclear IGFBP-2 is required for the activation of VEGF expression and consequent angiogenesis.

L1CAM stimulates glioma cell motility and proliferation through the fibroblast growth factor receptor

The L1CAM cell adhesion/recognition molecule (L1, CD171) and fibroblast growth factor receptor (FGFR) both are expressed by human high-grade glioma cells, but their potential actions in controlling cell behavior have not been linked. L1 actions in cancer cells have been attributed mainly to integrin receptors, and we demonstrated previously that L1-stimulated glioma cell migration correlates with integrin expression, increased focal adhesion kinase activation and focal complex turnover. Our analyses of datasets revealed FGFR is overexpressed in glioma regardless of grade, while ADAM10 metalloprotease expression increases with glioma grade. Here, we used dominant-negative and short hairpin RNA approaches to inhibit the activation of FGFR1 and expression of L1, respectively. An L1 peptide that inhibits L1-FGFR interaction and PD173074, a chemical inhibitor of FGFR1 activity, also were used to elucidate the involvement of L1-FGFR interactions on glioma cell behavior. Time-lapse cell motility studies and flow cytometry cell cycle analyses showed that L1 operates to increase glioma cell motility and proliferation through FGFR activation. Shutdown of both L1 expression and FGFR activity in glioma cells resulted in a complete termination of cell migration in vitro. These studies show for the first time that soluble L1 ectodomain (L1LE) acts on glioma cells through FGFRs, and that FGFRs are used by glioma cells for increasing motility as well as proliferation in response to activation by L1LE ligand. Thus, effective treatment of high-grade glioma may require simultaneous targeting of L1, FGFRs, and integrin receptors, which would reduce glioma cell motility as well as proliferation.

The influence of opioid peptides on matrix metalloproteinase-9 and urokinase plasminogen activator expression in three cancer cell lines

Matrix metalloproteinases (MMPs) and urokinase plasminogen activator (uPA) regulate proteolysis of the extracellular matrix (ECM) and as a consequence are involved in a number of physiological and pathological states, including cancer. A crucial feature of cancer progression and metastasis is the disruption of the ECM and spreading of proliferating cancer cells. Over-expression of MMPs and uPA is common for most types of cancers and correlates well with the adverse prognosis. Compounds able to modulate the activity of these proteolytic enzymes may become important agents in cancer therapy. In the present study, we examined the effect of the mu-opioid receptor selective peptide, morphiceptin, and its two synthetic analogs on mRNA and protein levels of MMP-9 and uPA in three human cancer cell lines: MCF-7, HT-29, and SH-SY5Y. Our findings indicate that in all three cell lines morphiceptin and its analogs attenuated MMP-9 expression and secretion and that this effect is not mediated by opioid receptors but is under control of the nitric oxide system. On the other hand, tested opioids up-regulated uPA levels through a mechanism that involved opioid-receptors. Different pathways by which opioid peptides exert their actionin cancer cells can explain their contradictory influence on the level of cancer markers.

Diethyldithiocarbamate complex with copper: the mechanism of action in cancer cells

The idea of "repurposing" of existing drugs provides an effective way to develop and identify new therapies. Disulfiram (Antabuse), a drug commonly used for the treatment of alcoholism, shows promising anticancer activity in both preclinical and clinical studies. In the human body, disulfiram is rapidly converted to its reduced metabolite, diethyldithiocarbamate. If copper ions are available, a bis(diethyldithiocarbamate)-copper(II) complex is formed. Disulfiram's selective anticancer activity is attributed to the copper(II) complex's ability to inhibit the cellular proteasome. It is assumed that the complex inhibits the proteasome by a mechanism that is distinct to the clinically used drug bortezomib, targeting the 19S rather than the 20S proteasome. This difference could be explained by inhibition of the JAMM domain of the POH1 subunit within the lid of the 19S proteasome.

P37 Pro-apoptotic effect of hydrogen sulphide in human melanoma cell lines: A signal transduction analysis

Background The need for new drugs in melanoma treatment is of great relevance. Indeed, current therapies for the treatment of metastatic melanoma offer a limited clinical benefit and only in recent years there has been an advancement due to the identification of new molecular targets [1] . Hydrogen sulphide (H 2 S) is endogenously produced by the action of three enzymes CBS, CSE and the newly discovered 3-MST [2] . While H 2 S is cytoprotective at physiological concentrations, it seems to have pro-apoptotic actions in cancer cells [3] . However, to date there are not definitive reports on the role played by H 2 S in cancer development. Aim of this study was to determine the possible involvement of H 2 S in human melanoma. Methods The study has been performed by using some relevant human melanoma cell lines such as A375, WM115 and SK-Mel-28. HaCat, a normal human fibroblast cell line, has been used as control. Cellular proliferation was evaluated by the MTT assay. Apoptosis was assayed by flow cytometry analysis by double staining with Annexin V and propidium iodide (PI). NF-kB/DNA-binding activity was evaluated by electrophoretic mobility shift assay. Expression of CBS, CSE, 3-MST was assayed by quantitative real time RT-PCR, expression of Bcl-2, XIAP, c-FLIP, caspase 3, PARP, IKBa and Akt/p-Akt was determined by western blotting. Levels of H 2 S in the supernatant and in total cellular extracts were assayed by colorimetric assay. Results Diallyl trisulfide (DATS) is a garlic-derived polysulfide able to release H 2 S [4] . Our results demonstrate that DATS greatly suppressed, in a time and concentration-dependent manner, proliferation of the three human melanoma cell lines used. The most striking effect was obtained on the A375 cell line whose proliferation was inhibited, following incubation with DATS (10–30–100 μM, 72 h) by 30%, 70%, and 78% respectively ( p 2 S levels found in both supernatants and cellular lysates. Conversely, DATS up to 300 μM did not affect proliferation of HaCat. DATS-induced inhibition of A375 proliferation (10–100 μM, 72 h) was almost completely reversed by haemoglobin (10 μM; p 2 S. Moreover, DATS-induced inhibition of A375 proliferation was due to the induction of apoptosis as demonstrated by FACS analysis with Annexin V/PI staining and further confirmed by the inhibition of Bcl-2, XIAP, FLIP, as well as by the cleavage and consequent activation of caspase-3 and inactivation of poly (ADP ribose) polymerase (PARP-1). Constitutive NF-kB and activated Akt expression have been described in melanoma [5] . We also demonstrated that H 2 S released by DATS suppressed both constitutive NF-kB/DNA-binding activity and Akt phosphorylation suggesting that the apoptotic effect observed following exposure to H 2 S was consistent with the signal transduction pathways activated. Conclusion In conclusion, we demonstrate that H 2 S triggers, in relevant human melanoma cell lines, an apoptotic effect. This effect, in turn, activates downstream a signal pattern that candidates H 2 S as a possible novel therapeutic/target or diagnostic tool.