A novel triazolonaphthalimide induces apoptosis and inhibits tumor growth by targeting DNA and DNA-associated processes.
ABSTRACT: DNA and DNA-associated processes have been classes of the most important targets of chemotherapeutic drugs. As classic DNA intercalators and topoisomerase inhibitors, naphthalimides have been extensively investigated as potential anti-cancer drugs. We recently synthesized a novel series of triazolonaphthalimides with excellent anti-cancer activities. In the present study, one of the most potent triazolonaphthalimides, LSS-11, was investigated. LSS-11 bound to DNA in vitro and in cell mainly by minor groove binding and significantly increased the stability of DNA, which could be fundamental for the biological activities of LSS-11. In addition to inhibiting DNA topoisomerase II-catalyzed decatenation of knotted circulated DNA, LSS-11 dramatically inhibited DNA replication mediated by polymerase chain reaction and isothermal helicase-dependent amplification, as well as the expression of luciferase driven by a minimal TA promoter in cell. Furthermore, LSS-11 exhibited strong cytotoxicity in selected human colon cancer cell lines by inducing cell cycle arrest and apoptosis, which was accompanied by DNA damage response. Finally, LSS-11 potently inhibited the growth of S180 murine sarcoma and SW480 human colorectal cancer xenografts in vivo without significant major toxicities. These results suggest that LSS-11 deserves further research and development as a novel anti-cancer agent, and provided new understandings of mechanisms by which LSS-11 inhibited multiple DNA-associated processes and tumor growth.
Project description:Background: In the discovery of DNA intercalators, ?-carbolines compose one member of the most interesting alkaloid family and are of clinical importance. In the efforts, N-(3-benzyloxycarbonyl-?-carboline-1-yl)ethyl-Ser-Ala-OBzl (BCESA) was designed as a nano-scaled DNA intercalator without Dox-like toxicity. Methods: Based on the structural analysis and CDOCKER energy comparison, BCESA was rationally designed as such a nano-scaled intercalator. The anti-tumor activity, the toxicity and the tumor targeting action of BCESA were evaluated on mouse models. Results: The in vitro proliferation of cancer cells, but not non-cancer cells, was effectively inhibited by BCESA. On S180 mouse model BCESA dose-dependently slowed the tumor growth, and 0.01 ?mol/kg/day was found as a minimal effective dose. Both BCESA and its moiety were found in the tumor tissue, but not in the organs and the blood, of S180 mice. Conclusion: BCESA should be a nano-scaled intercalator capable of targeting tumor tissue to release anti-tumoral ?-carboline-3-carboxylic acid and its 1-methyl derivative, while Ser-Ala-OBzl is a simple and desirable carrier.
Project description:Multidrug resistance (MDR) is a major cause of the inefficacy and poor response to paclitaxel-based chemotherapy. The combination of conventional cytotoxic drugs has been a plausible strategy for overcoming paclitaxel resistance. Herein, we investigated the cytotoxic effects and underlying mechanism of LSS-11, a novel naphthalimide derivative-based topoisomerase inhibitor, in paclitaxel-resistant A549 (A549/T) lung cancer cells. LSS-11 enhanced cell death in A549/T cells by inducing apoptosis through increasing the DR5 protein level and PARP1 cleavage. Importantly, LSS-11 dose-dependently reduced STAT3 phosphorylation and downregulated its target genes MDR1 and MRP1, without affecting P-gp transport function. Chromatin coimmunoprecipitation (ChIP) assay further revealed that LSS-11 hindered the binding of STAT3 to the MDR1 and MRP1 promoters. Additionally, pharmacological inhibition of p-STAT3 by sulforaphane downregulated MDR1 and MRP1, resulting in A549/T cell death by triggering apoptosis. Collectively, our data show that LSS-11 is a potent naphthalimide-based chemosensitizer that could enhance cell death in paclitaxel-resistant lung cancer cells through the DR5/PARP1 pathway and STAT3/MDR1/MRP1 STAT3 inhibition.
Project description:Many anti-tumor drugs function by intercalating into DNA. The xanthine alkaloid caffeine can also intercalate into DNA as well as form ?-? molecular complexes with other planar alkaloids and anti-tumor drugs. The presence of caffeine could interfere with the intercalating anti-tumor drug by forming ?-? molecular complexes with the drug, thereby blocking the planar aromatic drugs from intercalating into the DNA and ultimately lowering the toxicity of the drug to the cancer cells. The cytotoxic activities of several known DNA intercalators (berberine, camptothecin, chelerythrine, doxorubicin, ellipticine, and sanguinarine) on MCF-7 breast cancer cells, both with and without caffeine present (200 ?g/mL) were determined. Significant attenuation of the cytotoxicities by caffeine was found. Computational molecular modeling studies involving the intercalating anti-tumor drugs with caffeine were also carried out using density functional theory (DFT) and the recently developed M06 functional. Relatively strong ?-? interaction energies between caffeine and the intercalators were found, suggesting an "interceptor" role of caffeine protecting the DNA from intercalation.
Project description:Ovarian cancer is the most lethal gynecological malignancy, often because of the frequent insurgence of chemoresistance to the drugs currently used. Thus, new therapeutical agents are needed. We tested the toxicity of 16 new DNA-intercalating agents to cisplatin (cDDP)-sensitive human ovarian carcinoma cell lines and their resistant counterparts. The compounds were the complexes of Pt(II) or Pd(II) with bipyridyl (bipy) and phenanthrolyl (phen) and with four different thiourea ancillary ligands. Within each of the four series of complexes characterized by the same thiourea ligand, the Pd(phen) drugs invariably showed the highest anti-proliferative efficacy. This paralleled both a higher intracellular drug accumulation and a more efficient DNA intercalation than all the other metal-bidentate ligand combinations. The consequent inhibition of topoisomerase II activity led to the greatest inhibition of DNA metabolism, evidenced by the inhibition of the expression of the folate cycle enzymes and a marked perturbation of cell-cycle distribution in both cell lines. These findings indicate that the particular interaction of Pd(II) with phenanthroline confers the best pharmacokinetic and pharmacodynamic properties that make this class of DNA intercalators remarkable inhibitors, even of the resistant cell growth.
Project description:To discover novel drugs for neuroblastoma treatment, we have previously screened a panel of drugs and identified 30 active agents against neuroblastoma cells. Here we performed microarray gene expression analysis to monitor the impact of these agents on a neuroblastoma cell line and used the connectivity map (cMAP) to explore putative mechanism of action of unknown drugs. We first compared the expression profiles of 10 compounds shared in both our dataset and cMAP database and observed the high connectivity scores for 7 of 10 matched drugs regardless of the differences of cell lines utilized. The screen of cMAP for uncharacterized drugs indicated the signature of Epoxy anthraquinone derivative (EAD) matched the profiles of multiple known DNA targeted agents (topoisomerase I/II inhibitors, DNA intercalators, and DNA alkylation agents) as predicted by its structure. Similar result was obtained by querying against our internal NB-cMAP (http://pob.abcc.ncifcrf.gov/cgi-bin/cMAP), a database containing the profiles of 30 active drugs. These results suggest that Epoxy anthraquinone derivative may inhibit neuroblastoma cells by targeting DNA replication inhibition. Experimental data also demonstrate that Epoxy anthraquinone derivative indeed induces DNA double-strand breaks through DNA alkylation and inhibition of topoisomerase activity. Our study indicates that Epoxy anthraquinone derivative may be a novel DNA topoisomerase inhibitor that can be potentially used for treatment of neuroblastoma or other cancer patients.
Project description:Topoisomerase II poisons are in clinical use as anti-cancer therapy for decades and work by stabilizing the enzyme-induced DNA breaks. In contrast, catalytic inhibitors block the enzyme before DNA scission. Although several catalytic inhibitors of topoisomerase II have been described, preclinical concepts for exploiting their anti-proliferative activity based on molecular characteristics of the tumor cell have only recently started to emerge. Topoisomerase II is an ATPase and uses the energy derived from ATP hydrolysis to orchestrate the movement of the DNA double strands along the enzyme. Thus, interfering with ATPase function with low molecular weight inhibitors that target the nucleotide binding pocket should profoundly affect cells that are committed to undergo mitosis.Here we describe the discovery and characterization of a novel purine diamine analogue as a potent ATP-competitive catalytic inhibitor of topoisomerase II. Quinoline aminopurine compound 1 (QAP 1) inhibited topoisomerase II ATPase activity and decatenation reaction at sub-micromolar concentrations, targeted both topoisomerase II alpha and beta in cell free assays and, using a quantitative cell-based assay and a chromosome segregation assay, displayed catalytic enzyme inhibition in cells. In agreement with recent hypothesis, we show that BRCA1 mutant breast cancer cells have increased sensitivity to QAP 1.The results obtained with QAP 1 demonstrate that potent and selective catalytic inhibition of human topoisomerase II function with an ATP-competitive inhibitor is feasible. Our data suggest that further drug discovery efforts on ATP-competitive catalytic inhibitors are warranted and that such drugs could potentially be developed as anti-cancer therapy for tumors that bear the appropriate combination of molecular alterations.
Project description:Hemocyanin is a multifunctional glycoprotein, which also plays multiple roles in immune defense. While it has been demonstrated that hemocyanin from some mollusks can induce potent immune response and is therefore undergoing clinical trials to be used in anti-tumor immunotherapy, little is currently known about how hemocyanin from arthropods affect tumors. In this study we investigated the anti-tumor activity of hemocyanin from Litopenaeus vannamei on Sarcoma-180 (S180) tumor-bearing mice model. Eight days treatment with 4mg/kg bodyweight of hemocyanin significantly inhibited the growth of S180 up to 49% as compared to untreated. Similarly, histopathology analysis showed a significant decrease in tumor cell number and density in the tissues of treated mice. Moreover, there was a significant increase in immune organs index, lymphocyte proliferation, NK cell cytotoxic activity and serum TNF-? level, suggesting that hemocyanin could improve the immunity of the S180 tumor-bearing mice. Additionally, there was a significant increase in superoxide dismutase (SOD) activity and a decrease in the level of malondialdehyde (MDA) in serum and liver, which further suggest that hemocyanin improved the anti-oxidant ability of the S180 tumor-bearing mice. Collectively, our data demonstrated that L. vannamei hemocyanin had a significant antitumor activity in mice.
Project description:Arterial thrombosis is one of the major complications of cancer and can seriously worsen the prognosis of the patients. These clinical findings encouraged this paper to correlate P-selectin inhibition and DNA intercalation in cancer therapy and complicated thrombosis. By designing and docking 12 derivatives of bisindole- 2-carboxylic acids into the active sites of P-selectin and d(CGATCG)2 9 derivatives were assigned to receive in vivo anti-tumor assay, and finally provided dimethyl 2,2'-[(2,2'-(ethane-1,1-diyl)bis(1H-indole-3,2-diyl)]diacetate (DEBIC) to receive assays. DEBIC intercalated DNA and inhibited proliferation of tumor cells but not non-tumor cells. It slowed tumor growth of S180 mice at a dose of 0.36 ?mol/kg, and slowed tumor growth of A549 bearing BABL/C mice at a dose of 8.9 ?mol/kg. DEBIC was also found to inhibit arterial thrombosis by down regulating P-selectin effectively at a dose of 0.36 ?mol/kg.
Project description:DNA topoisomerase II (Top2) is the target of some of the most effective anticancer DNA intercalators. To determine the effect of intercalating ligands at defined positions relative to a known DNA cleavage site for human Top2alpha, we synthesized oligodeoxynucleotides containing single trans-opened benzo[a]pyrene 7,8-diol 9,10-epoxide (DE) deoxyadenosine (dA) adducts of known absolute configuration, placed at specific positions in a duplex sequence containing staggered Top2 cleavage sites on both strands. Because the orientations of the intercalated hydrocarbon are known from NMR solution structures of duplex oligonucleotides containing these dA adducts, a detailed analysis of the relationship between the position of intercalation and trapping of Top2 is possible. Our findings demonstrate that (i) Top2 cleavage complexes are trapped by intercalation of the hydrocarbon at either of the staggered cleavage sites or immediately adjacent to the base pairs flanking the cleavage sites within the stagger; (ii) both concerted and nonconcerted cleavage by both subunits of a Top2 homodimer were detected depending on the position of the benzo[a]pyrene DE dA adduct; and (iii) intercalation immediately outside of the staggered Top2 cleavage site, and to a lesser extent in the middle of the stagger, prevents Top2 from cleaving DNA at this site, consistent with the effect of some intercalators as suppressors of Top2-mediated DNA cleavage. These results identify specific binding sites for intercalators that result in trapping of Top2. Such poisoning of Top2 by bulky polycyclic aromatic hydrocarbon DE adducts constitutes a potential mechanism for their carcinogenic activity.
Project description:We have previously demonstrated that polymerases such as telomerase can be inhibited by molecules (e.g., intercalators) that target the key RNA/DNA duplex substrate. In this work we show that this also holds true for reverse transcriptase, and show that the lead intercalators can be modified to increase inhibition efficacy. Specifically, we use the strategy of multiple simultaneous intercalation, by linking two intercalators with a variable linker. The rationale behind this design is that a specific linker has the potential to increase affinity and specificity for the target duplex. We have synthesized a library of 45 ethidium bis-intercalators in which the distance between intercalators is systematically varied. We observe that members of the dimer library have improved telomerase and reverse transcriptase inhibition, relative to the monomeric leads. We show that this improvement in inhibition over mono-intercalators is most prominent when non-productive sites of inhibitor binding are limited in the assay mix. When this is done, a 400-fold increase in inhibition efficacy is observed.