Efficacious Anticancer Drug Delivery Mediated by a pH-Sensitive Self-Assembly of a Conserved Tripeptide Derived from Tyrosine Kinase NGF Receptor

We present herein a short tripeptide sequence (Lys-Phe-Gly or KFG) that is situated in the juxtamembrane region of the tyrosine kinase nerve growth factor (Trk NGF) receptors. KFG self-assembles in water and shows a reversible and concentration-dependent switching of nanostructures from nanospheres (vesicles) to nanotubes, as evidenced by dynamic light scattering, transmission electron microscopy, and atomic force microscopy. The morphology change was associated with a transition in the secondary structure. The tripeptide vesicles have inner aqueous compartments and are stable at pH7.4 but rupture rapidly at pH approximate to 6. The pH-sensitive response of the vesicles was exploited for the delivery of a chemotherapeutic anticancer drug, doxorubicin, which resulted in enhanced cytotoxicity for both drug-sensitive and drug-resistant cells. Efficient intracellular release of the drug was confirmed by fluorescence-activated cell sorting analysis, fluorescence microscopy, and confocal microscopy.

Identification and characterization of novel indole based small molecules as anticancer agents through SIRT1 inhibition

In our pursuit to develop new potential anticancer leads, we designed a combination of structural units of indole and substituted triazole; and a library of 1-{1-methyl-2-4-phenyl-5-(propan-2-ylsulfanyl)-4H-1,2,4-triazol-3-yl ]-1H-indol-3-yl}methanamine derivatives was synthesized and characterized. Cytotoxic evaluations of these molecules over a panel of three human cancer cell lines were carried out. Few molecules exhibited potent growth inhibitory action against the treated cancer cell lines at lower micro molar concentration. An in vitro assay investigation of these active compounds using recombinant human SIRT1 enzyme showed that one of the compounds (IT-14) inhibited the deacetylation activity of the enzyme. The in vivo study of IT-14 exemplified its promising action by reducing the prostate weight to the body weight ratio in prostate hyperplasia animal models. A remarkable decrease in the disruption of histoarchitecture of the prostate tissues isolated from IT-14 treated animal compared to that of the positive control was observed. The molecular interactions with SIRT1 enzyme were also supported by molecular docking simulations. Hence this compound can act as a lead molecule to treat prostatic hyperplasia. (C) 2013 Elsevier Masson SAS. All rights reserved.

Mitochondria-Targeted Photoinduced Anticancer Activity of Oxidovanadium( IV) Complexes of Curcumin in Visible Light

Oxidovanadium(IV) complexes VO(py-aebmz)(B)]Cl (1, 2) and VO(napth-py-aebmz)(cur)]Cl 3; py-aebmz = 2-(1H-benzimidazol-2-yl)-N-(pyridin-2-ylmethylene)ethanamine, HB = acetylacetone (Hacac, 1) and curcumin (Hcur, 2), napth-py-aebmz = naphthalimide conjugated to py-aebmz ] have been prepared, characterized and their photoinduced DNA cleavage activities and photocytotoxicities studied. Complexes 1-3 each exhibited an irreversible cyclic voltammetric response of the V-IV/V-III redox couple at around -0.85 V versus SCE in dmf/0.1 M tbap. The complexes showed DNA photocleavage activity in visible light of 454, 530 and 647 nm through hydroxyl radical and singlet oxygen pathways. Fluorescence microscopy data suggest mitochondrial localization of complex 3 bearing a naphthalimide with a two-fold increase in photocytotoxicity in HaCaT cells with an IC50 value of 6.3 M and a three-fold increase in MCF-7 cells with an IC50 of 5.4 M compared with complex 2. Both 2 and 3 were non-toxic in the dark.

Advances in the molecular design of potential anticancer agents via targeting of human telomeric DNA

Telomerases are an attractive drug target to develop new generation drugs against cancer. A telomere appears from the chromosomal termini and protects it from double-stranded DNA degradation. A short telomere promotes genomic instability, like end-to-end fusion and regulates the over-expression of the telomere repairing enzyme, telomerase. The telomerase maintains the telomere length, which may lead to genetically abnormal situations, leading to cancer. Thus, the design and synthesis of an efficient telomerase inhibitor is a viable strategy toward anticancer drugs development. Accordingly, small molecule induced stabilization of the G-quadruplex structure, formed by the human telomeric DNA, is an area of contemporary scientific art. Several such compounds efficiently stabilize the G-quadruplex forms of nucleic acids, which often leads to telomerase inhibition. This Feature article presents the discovery and development of the telomere structure, function and evolution in telomere targeted anticancer drug design and incorporates the recent advances in this area, in addition to discussing the advantages and disadvantages in the methods, and prospects for the future.

Ferrocenyl-L-amino acid copper(II) complexes showing remarkable photo-induced anticancer activity in visible light

Ferrocene-conjugated copper(II) complexes Cu(Fc-aa)(aip)](ClO4) (1-3) and (Cu(Fc-aa)(pyip)](ClO4) (4-6) of L-amino acid reduced Schiff bases (Fc-aa), 2-(9-anthryl)-1H-imidazo4,5-f]1,10]phenanthroline (aip) and 2-(1-pyrenyl)-1H-imidazo4,5-f] 1,10]phenanthroline (pyip), where Fc-aa is ferrocenylmethyl-L-tyrosine (Fc-Tyr in 1, 4), ferrocenylmethyl-L-tryptophan (Fc-Trp in 2, 5) and ferrocenylmethyl-L-methionine (Fc-Met in 3, 6), were prepared and characterized, and their photocytotoxicity was studied (Fc = ferrocenyl moiety). Phenyl analogues, viz. (Cu(Ph-Met)(aip)](ClO4) (7) and (Cu(Ph-Met)(pyip)](ClO4) (8), were prepared and used as control compounds. The bis-imidazophenanthroline copper(II) complexes, viz. (Cu(aip)(2)(NO3)](NO3) (9) and Cu(pyip)(2)(NO3)](NO3) (10), were also prepared and used as controls. Complexes 1-6 having a redox inactive cooper(II) center showed the Fc(+)-Fc redox couple at similar to 0.5 V vs. SCE in DMF-0.1 mol (Bu4N)-N-n](ClO4). The copper(II)-based d-d band was observed near 600 nm in DMF-Tris-HCl buffer (1 :1 v/v). The ferrocenyl complexes showed low dark toxicity, but remarkably high photocytotoxicity in human cervical HeLa and human breast adenocarcinoma MCF-7 cancer cells giving an excellent photo-dynamic effect while their phenyl analogues were inactive. The photo-exposure caused significant morphological changes in the cancer cells when compared to the non-irradiated ones. The photophysical processes were rationalized from the theoretical studies. Fluorescence microscopic images showed 3 and 6 localizing predominantly in the endoplasmic reticulum (ER) of the cancer cells, thus minimizing any undesirable effects involving nuclear DNA.

Substitution-Modulated Anticancer Activity of Half-Sandwich Ruthenium(II) Complexes with Heterocyclic Ancillary Ligands

Ten new organometallic half-sandwich ruthenium complexes with heterocyclic ligands have been synthesized (H1-H10). The substituents on the ancillary heterocyclic ligands were varied to understand the effect of substitution on anticancer activity. The crystallographic characterization of five complexes confirms that they adopt three-legged piano-stool structures and are stabilized by intramolecular hydrogen bonding. Complexes H2 and H3 also exhibit halogen bonding in the solid state. In aqueous media, the complexes form dinuclear ruthenium species. Complex H1 with a noncytotoxic heterocycle, 6-fluoro-2-mercaptobenzothiazole, and complex H11 with the unsubstituted 2-mercaptobenzothiazole are the most active against A2780 and KB cell lines. The substitution of the H atoms on the ancillary ligand with Cl or Br atoms leads to a decrease in the anticancer activity. With the exception of fluorine-substituted H5, the complexes with mercaptobenzoxazole (H6-H9) are inactive against all of the tested cell lines. Ruthenium complexes with mercaptonaphthimidazole (H10) and mercaptobenzimidazole (H13) do not show any anticancer activity. The active complexes show a biphasic melting curve when incubated with calf thymus (CT) DNA. These complexes only inhibit thioredoxin reductase (TrxR) enzyme activity to a small extent. The substitution of hydrogen atoms with fluorine atoms in the aromatic heterocyclic ligands on organometallic half-sandwich ruthenium complexes has the most beneficial effect on their anticancer activity.

Dual enzyme responsive and targeted nanocapsules for intracellular delivery of anticancer agents

We report the fabrication of dual enzyme responsive hollow nanocapsules which can be targeted to deliver anticancer agents specifically inside cancer cells. The enzyme responsive elements, integrated in the nanocapsule walls, undergo degradation in the presence of either trypsin or hyaluronidase leading to the release of encapsulated drug molecules. These nanocapsules, which were crosslinked and functionalised with folic acid, showed minimal drug leakage when kept in pH 7.4 PBS buffer, but released the drug molecules at a rapid rate in the presence of either one of the triggering enzymes. Studies on cellular interactions of these nanocapsules revealed that doxorubicin loaded nanocapsules were taken up by cervical cancer cells via folic acid receptor medicated endocytosis. Interestingly the nanocapsules were able to disintegrate inside the cancer cells and release doxorubicin which then migrated into the nucleus to induce cell death. This study indicates that these nanocapsules fabricated from biopolymers can serve as an excellent platform for targeted intracellular drug delivery to cancer cells.

Anticancer Effects of Brominated Indole Alkaloid Eudistomin H from Marine Ascidian Eudistoma viride Against Cervical Cancer Cells (HeLa)

Marine invertebrates called ascidians are prolific producers of bioactive substances. The ascidian Eudistoma viride, distributed along the Southeast coast of India, was investigated for its in vitro cytotoxic activity against human cervical carcinoma (HeLa) cells by the MTT assay. The crude methanolic extract of E. viride, with an IC50 of 53 mu g/ml, was dose-dependently cytotoxic. It was more potent at 100 mu g/ml than cyclohexamide (1 mu g/ml), reducing cell viability to 9.2%. Among nine fractions separated by chromatography, ECF-8 exhibited prominent cytoxic activity at 10 mu g/ml. The HPLC fraction EHF-21 of ECF-8 was remarkably dose- and time-dependently cytotoxic, with 39.8% viable cells at 1 mu g/ml compared to 51% in cyclohexamide-treated cells at the same concentration; the IC50 was 0.49,mu g/ml. Hoechst staining of HeLa cells treated with EHF-2I at 0.5 mu g/ml revealed apoptotic events such an cell shrinkage, membrane blebbing, chromatin condensation and formation of apoptotic bodies. Cell size and granularity study showed changes in light scatter, indicating the characteristic feature of cells dying by apoptosis. The cell-cycle analysis of HeLa cells treated with fraction EHF-21 at 1 mu g/ml showed the marked arrest of cells in G(0)/G(1), S and G(2)/M phases and an increase in the sub G(0)/G(1) population indicated an increase in the apoptotic cell population. The statistical analysis of the sub-G(1) region showed a dose-dependent induction of apoptosis. DNA fragmentation was also observed in HeLa cells treated with EHF-21. The active EHF-2I fraction, a brominated indole alkaloid Eudistomin H, led to apoptotic death of HeLa cells.

Predicting clinical response to anticancer drugs using an ex vivo platform that captures tumour heterogeneity

Predicting clinical response to anticancer drugs remains a major challenge in cancer treatment. Emerging reports indicate that the tumour microenvironment and heterogeneity can limit the predictive power of current biomarker-guided strategies for chemotherapy. Here we report the engineering of personalized tumour ecosystems that contextually conserve the tumour heterogeneity, and phenocopy the tumour microenvironment using tumour explants maintained in defined tumour grade-matched matrix support and autologous patient serum. The functional response of tumour ecosystems, engineered from 109 patients, to anticancer drugs, together with the corresponding clinical outcomes, is used to train a machine learning algorithm; the learned model is then applied to predict the clinical response in an independent validation group of 55 patients, where we achieve 100% sensitivity in predictions while keeping specificity in a desired high range. The tumour ecosystem and algorithm, together termed the CANScript technology, can emerge as a powerful platform for enabling personalized medicine.

Pluronic copolymer encapsulated SCR7 as a potential anticancer agent

Nonhomologous end joining (NHEJ) of DNA double strand breaks (DSBs) inside cells can be selectively inhibited by 5,6-bis-(benzylideneamino)-2-mercaptopyrimidin-4-ol (SCR7) which possesses anticancer properties. The hydrophobicity of SCR7 decreases its bioavailability which is a major setback in the utilization of this compound as a therapeutic agent. In order to circumvent the drawback of SCR7, we prepared a polymer encapsulated form of SCR7. The physical interaction of SCR7 and Pluronic (R) copolymer is evident from different analytical techniques. The in vitro cytotoxicity of the drug formulations is established using the MTT assay.

Protamine-carboxymethyl cellulose magnetic nanocapsules for enhanced delivery of anticancer drugs against drug resistant cancers

Multidrug resistance is a major therapeutic challenge faced in the conventional chemotherapy. Nanocarriers are beneficial in the transport of chemotherapeutics by their ability to bypass the P-gp efflux in cancers. Most of the P-gp inhibitors under phase II clinical trial are facing failures and hence there is a need to develop a suitable carrier to address P-gp efflux in cancer therapy. Herein, we prepared novel protamine and carboxymethyl cellulose polyelectrolyte multi-layered nanocapsules modified with Fe3O4 nanoparticles for the delivery of doxorubicin against highly drug resistant HeLa cells. The experimental results revealed that improved cellular uptake, enhanced drug intensity profile with greater percentage of apoptotic cells was attained when doxorubicin loaded magnetic nanocapsules were used in the presence of external magnetic field. Hence, we conclude that this magnetic field assisted nanocapsule system can be used for delivery of chemotherapeutics for potential therapeutic efficacy at minimal dose in multidrug resistant cancers. From the Clinical Editor: Many cancer drugs fail when cancer cells become drug resistant. Indeed, multidrug resistance (MDR) is a major therapeutic challenge. One way that tumor cells attain MDR is by over expression of molecular pumps comprising of P-glycoprotein (P-gp) and multidrug resistant proteins (MRP), which can expel chemotherapeutic drugs out of the cells. In this study, the authors prepared novel protamine and carboxymethyl cellulose polyelectrolyte multi-layered nanocapsules modified with Fe3O4 nanoparticles for the delivery of doxorubicin. The results show that there was better drug delivery and efficacy even against MDR tumor cells. (C) 2015 Elsevier Inc. All rights reserved.

Synthesis and evaluation of the biological activity of N `-2-oxo-1,2 dihydro-3H-indol-3-ylidene] benzohydrazides as potential anticancer agents

New N'-2-oxo-1,2-dihydro-3H-indol-3-ylidene]benzohydrazide derivatives were synthesized and evaluated for their cytotoxic properties against murine leukemia, L1210, human leukemia, REH and K562, human T-cell leukemia, CEM and human cervix carcinoma, HeLa cells. Among the tested compounds, the 3,4,5-trimethoxy-N'-5-methyl-2-oxo-1,2-dihydro-3H-indol-3-ylidene]ben zohydrazide derivative (5t) emerged as the most potent inhibitor against all the tumor cell lines evaluated. To investigate the mechanism of action, 5t was further studied by cell cycle analysis, mitochondrial membrane potential analysis, DNA fragmentation and Annexin V-FITC flow cytometric analysis, which suggested that 5t was able to induce apoptosis at submicromolar range.

Metal Complexes of Curcumin for Cellular Imaging, Targeting, and Photoinduced Anticancer Activity

CONSPECTUS: Curcumin is a polyphenolic species. As an active ingredient of turmeric, it is well-known for its traditional medicinal properties. The therapeutic values include antioxidant, anti-inflammatory, antiseptic, and anticancer activity with the last being primarily due to inhibition of the transcription factor NF-kappa B besides affecting several biological pathways to arrest tumor growth and its progression. Curcumin with all these positive qualities has only remained a potential candidate for cancer treatment over the years without seeing any proper usage because of its hydrolytic instability involving the diketo moiety in a cellular medium and its poor bioavailability. The situation has changed considerably in recent years with the observation that curcumin in monoanionic form could be stabilized on binding to a metal ion. The reports from our group and other groups have shown that curcumin in the metal-bound form retains its therapeutic potential. This has opened up new avenues to develop curcumin-based metal complexes as anticancer agents. Zinc(II) complexes of curcumin are shown to be stable in a cellular medium. They display moderate cytotoxicity against prostate cancer and neuroblastoma cell lines. A similar stabilization and cytotoxic effect is reported for (arene)ruthenium(II) complexes of curcumin against a variety of cell lines. The half-sandwich 1,3,5-triaza-7-phosphatricyclo-3.3.1.1]decane (RAPTA)-type ruthenium(II) complexes of curcumin are shown to be promising cytotoxic agents with low micromolar concentrations for a series of cancer cell lines. In a different approach, cobalt(III) complexes of curcumin are used for its cellular delivery in hypoxic tumor cells using intracellular agents that reduce the metal and release curcumin as a cytotoxin. Utilizing the photophysical and photochemical properties of the curcumin dye, we have designed and synthesized photoactive curcumin metal complexes that are used for cellular imaging by fluorescence microscopy and damaging the cancer cells on photoactivation in visible light while being minimally toxic in darkness. In this Account, we have made an attempt to review the current status of the chemistry of metal curcumin complexes and present results from our recent studies on curcumin complexes showing remarkable in vitro photocytotoxicity. The undesirable dark toxicity of the complexes can be reduced with suitable choice of the metal and the ancillary ligands in a ternary structure. The complexes can be directed to specific subcellular organelles. Selectivity by targeting cancer cells over normal cells can be achieved with suitable ligand design. We expect that this methodology is likely to provide an impetus toward developing curcumin-based photochemotherapeutics for anticancer treatment and cure.