Recent Synthesis and Discovery of Brefeldin A Analogs

The recent development of analogs of brefeldin A (BFA), a fungal metabolite, for the improvement of BFA apoptosis-inducing activity is described. BFA has been isolated from various soil or, more recently, marine fungi and has shown versatile beneficial activities. More importantly, the apoptosis-inducing activity of BFA in cancer cells highlights the possibility of further developing this natural product as an anticancer agent. Besides its biological importance, its structural features have also gathered tremendous interest from both medicinal and synthetic chemists. By a medicinal chemistry and total synthesis approach, numerous analogs from BFA have been developed to improve its inferior bioavailability and its antiproliferative ability. In this review, the recent medicinal chemistry efforts in relation to the production of BFA analogs are extensively presented.

Antitumor Effect of Pomolic Acid in Acute Myeloid Leukemia Cells Involves Cell Death, Decreased Cell Growth and Topoisomerases Inhibition

BACKGROUND

Acute myeloid leukemia (AML) represents the largest number of annual deaths from hematologic malignancy. In the United States, it was estimated that 21.380 individuals would be diagnosed with AML and 49.5% of patients would die in 2017. Therefore, the search for novel compounds capable of increasing the overall survival rate to the treatment of AML cells is urgent.

OBJECTIVES

To investigate the cytotoxicity effect of the natural compound pomolic acid (PA) and to explore the mechanism of action of PA in AML cell lines with different phenotypes.

METHODS

Three different AML cell lines, HL60, U937 and Kasumi-1 cells with different mechanisms of resistance were used to analyze the effect of PA on the cell cycle progression, on DNA intercalation and on human DNA topoisomerases (hTopo I and IIα) in vitro studies. Theoretical experiments of the inhibition of hTopo I and IIα were done to explore the binding modes of PA.

RESULTS

PA reduced cell viability, induced cell death, increased sub-G0/G1 accumulation and activated caspases pathway in all cell lines, altered the cell cycle distribution and inhibited the catalytic activity of both human DNA topoisomerases.

CONCLUSION

Finally, this study showed that PA has powerful antitumor activity against AML cells, suggesting that this natural compound might be a potent antineoplastic agent to improve the treatment scheme of this neoplasm.

Conceptually Novel Black Phosphorus/Cellulose Hydrogels as Promising Photothermal Agents for Effective Cancer Therapy

Black phosphorus (BP) has recently emerged as an intriguing photothermal agent in photothermal therapy (PTT) against cancer by virtue of its high photothermal efficiency, biocompatibility, and biodegradability. However, naked BP is intrinsically characterized by easy oxidation (or natural degradation) and sedimentation inside the tumor microenvironment, leading to a short-term therapeutic and inhomogeneous photothermal effect. Development of BP-based nanocomposites for PTT against cancer therefore remains challenging. The present work demonstrates that green and injectable composite hydrogels based on cellulose and BP nanosheets (BPNSs) are of great efficiency for PTT against cancer. The resultant cellulose/BPNS-based hydrogel possesses 3D networks with irregular micrometer-sized pores and thin, strong cellulose-formed walls and exhibits an excellent photothermal response, enhanced stability, and good flexibility. Importantly, this hydrogel nanoplatform is totally harmless and biocompatible both in vivo and in vitro. This work may facilitate the development of BP-polymer-based photothermal agents in the form of hydrogels for biomedical-related clinic applications.

Pinus Roxburghii essential oil anticancer activity and chemical composition evaluation

The present study was conducted to appraise the anticancer activity of Pinus roxburghii essential oil along with chemical composition evaluation. MTT assay revealed cytotoxicity induction in colon, leukemia, multiple myeloma, pancreatic, head and neck and lung cancer cells exposed to essential oil. Cancer cell death was also observed through live/dead cell viability assay and FACS analysis. Apoptosis induced by essential oil was confirmed by cleavage of PARP and caspase-3 that suppressed the colony-forming ability of tumor cells and 50 % inhibition occurred at a dose of 25 μg/mL. Moreover, essential oil inhibited the activation of inflammatory transcription factor NF-κB and inhibited expression of NF-κB regulated gene products linked to cell survival (survivin, c-FLIP, Bcl-2, Bcl-xL, c-Myc, c-IAP2), proliferation (Cyclin D1) and metastasis (MMP-9). P. roxburghii essential oil has considerable anticancer activity and could be used as anticancer agent, which needs further investigation to identify and purify the bioactive compounds followed by in vivo studies.

Characterization of naturally occurring pentacyclic triterpenes as novel inhibitors of deubiquitinating protease USP7 with anticancer activity in vitro

Deubiquitinating protease USP7 is a promising therapeutic target for cancer treatment, and interest in developing USP7 inhibitors has greatly increased. In the present study, we reported a series of natural pentacyclic triterpenes with USP7 inhibitory activity in vitro. Among them, both the ursane triterpenes and oleanane triterpenes were more active than the lupine triterpenes, whereas ursolic acid was the most potent with IC50 of 7.0±1.5 μmol/L. Molecular docking studies showed that ursolic acid might occupy the ubiquitin binding pocket of USP7, with the 17-carboxyl group and 3-hydroxyl group playing a vital role in the USP7-ursolic acid interaction. Using the cellular thermal shift assay, we demonstrated that ursolic acid interacted with USP7 in RPMI8226 human myeloma cells. Ursolic acid dose-dependently inhibited the proliferation of the myeloma cells with IC50 of 6.56 μmol/L, accompanied by reductions in USP7 substrates such as MDM2, UHRF1 and DNMT1. Overexpression of USP7 partially, but significantly attenuated ursolic acid-induced cell death as well as downregulation of MDM2, UHRF1 and DNMT1. In conclusion, we demonstrate for the first time that pentacyclic triterpenes represent a novel scaffold for developing USP7 inhibitors and that USP7 inhibition contributes to the anti-cancer effect of ursolic acid.

Skin Necrosis Due to the Extravasation of Irritant Anticancer Agents

A 70-year-old man with malignant lymphoma was subjected to a fourth course of chemotherapy using gemcitabine and cisplatin. During the intravenous infusion of anticancer agents, pain and redness was observed at the site of insertion. The patient was subsequently treated with the strongest topical steroids and topical cooling agents. However, 2 weeks later, the affected area turned yellow, and the histopathological findings revealed skin necrosis of the entire dermis layer. It took two and a half months to cure the lesion. Close attention should be paid to the development of skin necrosis even when irritant anticancer agents such as gemcitabine and cisplatin are administered.

Design and Synthesis of 3,4-diarylpyrrole Analogues as Potent Topoisomerase Inhibitors

BACKGROUND

The natural products containing a common 3,4-diarylpyrrole skeleton have attracted considerable attention due to their unique structures and multiplex biological activities. In our previous study, lycogarubin C was synthesized and showed cytotoxicity against MDAMB- 231, A549, PC3 and HeLa cell lines and topoisomerase II inhibitory activities.

OBJECTIVE

We present the design, synthesis and antitumor studies of 3,4-diarylprrole derivatives. Their antitumor activities and inhibitory activities against Topo I and Topo IIα of these compounds were assayed.

METHODS

A series of 3,4-diarylpyrrole analogues have been designed and synthesized. Their antiproliferation activities were evaluated by sulforhodamine B assay on human breast cancer MDAMB- 231, MDA-MB-435 and human cervical cancer HeLa cells.

RESULTS

Four compounds showed modest inhibitory activities against the growth of the three cell lines with IC50 below 50 μM. DNA relaxation assay revealed that compound 19o showed potent inhibitory activity against Topo IIα in vitro. 19o also induced DNA breaks in MDA-MB-435 cells evidenced by comet tails and the accumulation of γ-H2AX foci. The ability of 19o in inducing DNA breaks mediated by Topo IIα resulted in G2/M phase arrest and apoptosis.

CONCLUSION

This work indicates that 3,4-diarylpyrrole derivatives represent a novel type of Topo IIα inhibitory scaffold for developing new antitumor chemotherapeutic agents.

Development and Characterization of Solid Lipid Nanoparticles Loaded with a Highly Active Doxorubicin Derivative

Solid lipid nanoparticles (SLNs) comprise a versatile drug delivery system that has been developed for the treatment of a variety of diseases. The present study will investigate the feasibility of entrapping an active doxorubicin prodrug (a squalenoyl-derivative) in SLNs. The doxorubicin derivative-loaded SLNs are spherically shaped, have a mean diameter of 300-400 nm and show 85% w/w drug entrapment efficiency. The effects on cell growth of loaded SLNs, free doxorubicin and the prodrug have been examined using cytotoxicity and colony-forming assays in both human ovarian cancer line A2780 wild-type and doxorubicin-resistant cells. Further assessments as to the treatment's ability to induce cell death by apoptosis have been carried out by analyzing annexin-V staining and the activation of caspase-3. The in vitro data demonstrate that the delivery of the squalenoyl-doxorubicin derivative by SLNs increases its cytotoxic activity, as well as its apoptosis effect. This effect was particularly evident in doxorubicin-resistant cells.

Rottlerin as a novel chemotherapy agent for adrenocortical carcinoma

Adrenocortical carcinoma (ACC) is a rare, but aggressive endocrine malignancy with a generally poor clinical outcome. There is no effective therapy for advanced and metastatic ACC. In our study, we found that an existing drug (rottlerin) exerted its tumour-suppressive function in ACC. Specifically, rottlerin inhibited cellular proliferation of ACC cell lines (NCI-H295R and SW-13) in a dose- and time-dependent manner. We also found that rottlerin induced cell apoptosis and promoted G0/G1 cell cycle arrest in ACC cell lines. The cellular migration and invasion of ACC cell lines were decreased after treatment with rottlerin. Further, the molecular expression of lipoprotein receptor related protein 6 (LRP6) and β-catenin were down-regulated in rottlerin-treated ACC cells, which indicated that Wnt/β-catenin signaling was involved in the tumour-suppressive function of rottlerin. To further confirm the anti-tumour function of rottlerin, a nude mouse ACC xenograft model was used. The xenograft growth curves and TUNEL assays demonstrated that rottlerin inhibited proliferation and induced apoptosis in the ACC xenograft model. Furthermore, we verified that rottlerin down-regulated the expression of LRP6 and β-catenin in vivo. The ACC cell line and xenograft mouse model data indicated that rottlerin significantly inhibited proliferation and induced apoptosis of ACC cells, likely via suppression of the Wnt/β-catenin signaling pathway. Our study indicated the potential therapeutic utility of rottlerin as a novel and potential chemotherapeutic agent for ACC.

Insights into novel anticancer applications for apigenin

Flavonoids, naturally occuring derivatives of 2-phenyl-benzo-γ-pyrone, are widespread in plants as coloring substances. Apigenin (4',5,7,-trihydroxyflavone (5,7-dihydroxy-2-(4-hydroxyphenyl)-4H-1-benzopyran-4-one), molecular formula C₁₅H₁₀O⁵, is a flavonoid present in many fruits and vegetables, primarily in citrus fruits, apples, parsley and celery leaves. It is also found in some medicinal plants, including chamomile flowers, thyme, oregano, peppermint, lemon balm and yarrow, as a 7-O-glycoside with anti-inflammatory and antioxidant activity. In recent years it has attracted a great deal of interest as a bioactive substance reported to have anticancer properties. According to recent literature data, apigenin is able to reduce cancer cell glucose uptake, inhibit remodeling of the extracellular matrix, inhibit cell adhesion molecules that participate in cancer progression and hinder the development of blood vessels needed by growing tumors. It is reported to protect against a wide variety of cancers. The mechanism of anticancer activity is still under investigation and further research is needed.

Effects of a Rebamipide Mouthwash on Stomatitis Caused by Cancer Chemotherapy-Evaluation of the Efficacy by Patients Themselves

 Anticancer drug-induced stomatitis develops in 30% to 40% of cancer cases that undergo chemotherapy. However, medications for this condition are not commercially available in Japan. Upon obtaining approval of the ethics committee, a mouthwash containing rebamipide as the active ingredient (rebamipide mouthwash) was administered to one inpatient and four outpatients, who had developed stomatitis caused by cancer chemotherapy. Starting from 14 d after the administration of the rebamipide mouthwash, the patients scored a stomatitis survey on oral state, pain level, and diet and recorded the number of times they gargled, as well as any stomatitis observations, in a stomatitis diary. The total scores for the points for each of the three types of survey sections were classified into Grades 0 to 4 and evaluated as a stomatitis evaluation score (SES). The SES became "0" in three out of the five patients within 14 d of treatment. No change in SES was found in one patient. In the remaining patients, SES became "0" once but increased again later. Using image analysis software (ImageJ), the area at which the stomatitis was observed was measured. When comparing SES and change in the area in patients who agreed to participate, gradual reductions in the extent of stomatitis was observed even during the period when SES did not change. Having patients fill in an observation chart was effective for grasping changes in symptoms in outpatients.

Total syntheses of the archazolids: an emerging class of novel anticancer drugs

V-ATPase has recently emerged as a promising novel anticancer target based on extensive in vitro and in vivo studies with the archazolids, complex polyketide macrolides which present the most potent V-ATPase inhibitors known to date, rendering these macrolides important lead structures for the development of novel anticancer agents. The limited natural supply of these metabolites from their myxobacterial source renders total synthesis of vital importance for the further preclinical development. This review describes in detail the various tactics and strategies employed so far in archazolid syntheses that culminated in three total syntheses and discusses the future synthetic challenges that have to be addressed.

Symmetry-based approach to oligostilbenoids: Rapid entry to viniferifuran, shoreaphenol, malibatol A, and diptoindonesin G

The recognition of the local symmetric image within benzofuran-based natural oligostilbenoids guided us to design a modular synthetic approach to these molecules by utilizing a three-step sequence consisting of Sonogashira coupling, iodocyclization, and Suzuki coupling. During our synthesis, the relative reactivities of ester, aldehyde, and alkoxy groups on the same aryl ring toward the neighboring alkyne in the iodine-mediated cyclization reactions were explored. Starting from the symmetrical 3,5-dimethoxybenzyl alcohol, this route allowed rapid access to 2,3-diarylbenzofuran, a key intermediate to several oligostilbenoid natural products, in good overall yields.

Effect of Tea Polyphenol Compounds on Anticancer Drugs in Terms of Anti-Tumor Activity, Toxicology, and Pharmacokinetics

Multidrug resistance and various adverse side effects have long been major problems in cancer chemotherapy. Recently, chemotherapy has gradually transitioned from mono-substance therapy to multidrug therapy. As a result, the drug cocktail strategy has gained more recognition and wider use. It is believed that properly-formulated drug combinations have greater therapeutic efficacy than single drugs. Tea is a popular beverage consumed by cancer patients and the general public for its perceived health benefits. The major bioactive molecules in green tea are catechins, a class of flavanols. The combination of green tea extract or green tea catechins and anticancer compounds has been paid more attention in cancer treatment. Previous studies demonstrated that the combination of chemotherapeutic drugs and green tea extract or tea polyphenols could synergistically enhance treatment efficacy and reduce the adverse side effects of anticancer drugs in cancer patients. In this review, we summarize the experimental evidence regarding the effects of green tea-derived polyphenols in conjunction with chemotherapeutic drugs on anti-tumor activity, toxicology, and pharmacokinetics. We believe that the combination of multidrug cancer treatment with green tea catechins may improve treatment efficacy and diminish negative side effects.

Auranofin-mediated inhibition of PI3K/AKT/mTOR axis and anticancer activity in non-small cell lung cancer cells

Auranofin, a gold complex that has been used to treat rheumatoid arthritis in clinics and has documented pharmacokinetic and safety profiles in humans, has recently been investigated for its anticancer activity in leukemia and some solid cancers. However, auranofin's single agent activity in lung cancer is not well characterized. To determine whether auranofin has single agent activity in lung cancer, we evaluated auranofin's activity in a panel of 10 non-small cell lung cancer (NSCLC) cell lines. Cell viability analysis revealed that auranofin induced growth inhibition in a subset of NSCLC cell lines with a half maximal inhibitory concentration (IC₅₀) below 1.0 μM. Treatment with auranofin elicited apoptosis and necroptosis in auranofin-sensitive cell lines. Moreover, the susceptibility of NSCLC cells to auranofin was inversely correlated with TXNRD1 expression in the cells. Transient transfection of the TXNRD1-expressing plasmid in auranofin-sensitive Calu3 cells resulted in partial resistance, indicating that high TXNRD level is one of causal factors for resistance to auranofin. Further mechanistic characterization with proteomic analysis revealed that auranofin inhibits expression and/or phosphorylation of multiple key nodes in the PI3K/AKT/mTOR pathway, including S6, 4EBP1, Rictor, p70S6K, mTOR, TSC2, AKT and GSK3. Ectopic expression of TXNRD1 partially reversed auranofin-mediated PI3K/AKT/mTOR inhibition, suggesting that TXNRD1 may participate in the regulation of PI3K/AKT/mTOR pathway. Administration of auranofin to mice with xenograft tumors derived from NSCLC cells significantly suppressed tumor growth without inducing obvious toxic effects. Our results demonstrated feasibility of repurposing auranofin for treatment of lung cancer.

Evaluation of β-cyclodextrin-modified gemini surfactant-based delivery systems in melanoma models

Novel drug delivery systems are developed to improve the biological behavior of poorly soluble drugs and to improve therapeutic outcomes. In melanoma therapy, the goal is efficient drug delivery and mitigation of drug resistance. Melphalan (Mel), a currently used therapeutic agent for melanoma, requires solvent system for solubilization, leading to poor chemical stability. Moreover, drug resistance often renders the drug inefficient in clinical setting. A novel β-cyclodextrin-modified gemini surfactant (CDgemini) delivery system was developed to incorporate Mel in order to improve its physicochemical and biological behavior. Melphalan nanoparticles (Mel-NP) showed optimal particle size in the 200-250 nm range for endocytosis and induced significantly higher cell death compared with Mel (50% of inhibitory concentration [IC₅₀] of 36 µM for the complexes vs 82 µM for Mel). The CDgemini delivery system did not alter the pathway of the cellular death triggered by Mel and caused no intrinsic toxicity to the cells. The Mel-NP complexes induced significant cell death in melanoma cells that were rendered resistant to Mel. These findings demonstrate in principle the applicability of the CDgemini delivery system as safe and efficient alternative to the current melanoma therapy, especially in chemoresistant cases.

In vitro evaluation of a combination treatment involving anticancer agents and an aurora kinase B inhibitor

Aurora kinase B (AURKB) inhibitors are regarded as potential molecular-targeting drugs for cancer therapy. The present study evaluated the cytotoxic effect of a combination of AZD1152-hQPA, an AURKB inhibitor, and various anticancer agents on the HeLa human cervical cancer cell line, as well as its cisplatin-resistant equivalent HCP4 cell line. It was demonstrated that AZD1152-hQPA had an antagonistic effect on the cytotoxicity of cisplatin, etoposide and doxorubicin, but had a synergistic effect on that of all-trans-retinoic acid (ATRA), Am80 and TAC-101, when tested on HeLa cells. Cisplatin, etoposide and doxorubicin were shown to increase the cellular expression of AURKB, while ATRA, Am80 and TAC-101 downregulated its expression. These results suggested that AURKB expression is regulated by these anticancer agents at the transcriptional level, and that the level of expression of AURKB may influence the cytotoxic effect of AZD1152-hQPA. Therefore, when using anticancer agents, decreasing the expression of AURKB using a molecular-targeting drug may be an optimal therapeutic strategy.

The antitumour drug 7-ethyl-10-hydroxycamptothecin monohydrate and its solid-state hydrolysis mechanism on heating

7-Ethyl-10-hydroxycamptothecin [systematic name: (4S)-4,11-diethyl-4,9-dihydroxy-1H-pyrano[3',4':6,7]indolizino[1,2-b]quinoline-3,14(4H,12H)-dione, SN-38] is an antitumour drug which exerts activity through the inhibition of topoisomerase I. The crystal structure of SN-38 as the monohydrate, C₂₂H₂₀N₂O₅·H₂O, reveals that it is a monoclinic crystal, with one SN-38 molecule and one water molecule in the asymmetric unit. When the crystal is heated to 473 K, approximately 30% of SN-38 is hydrolyzed at its lactone ring, resulting in the formation of the inactive carboxylate form. The molecular arrangement around the water molecule and the lactone ring of SN-38 in the crystal structure suggests that SN-38 is hydrolyzed by the water molecule at (x, y, z) nucleophilically attacking the carbonyl C atom of the lactone ring at (x - 1, y, z - 1). Hydrogen bonding around the water molecules and the lactone ring appears to promote this hydrolysis reaction: two carbonyl O atoms, which are hydrogen bonded as hydrogen-bond acceptors to the water molecule at (x, y, z), might enhance the nucleophilicity of this water molecule, while the water molecule at (-x, y + 1/2, -z), which is hydrogen bonded as a hydrogen-bond donor to the carbonyl O atom at (x - 1, y, z - 1), might enhance the electrophilicity of the carbonyl C atom.

Recent advances in targeting the telomeric G-quadruplex DNA sequence with small molecules as a strategy for anticancer therapies

Human telomeric DNA (hTelo), present at the ends of chromosomes to protect their integrity during cell division, comprises tandem repeats of the sequence d(TTAGGG) which is known to form a G-quadruplex secondary structure. This unique structural formation of DNA is distinct from the well-known helical structure that most genomic DNA is thought to adopt, and has recently gained prominence as a molecular target for new types of anticancer agents. In particular, compounds that can stabilize the intramolecular G-quadruplex formed within the human telomeric DNA sequence can inhibit the activity of the enzyme telomerase which is known to be upregulated in tumor cells and is a major contributor to their immortality. This provides the basis for the discovery and development of small molecules with the potential for selective toxicity toward tumor cells. This review summarizes the various families of small molecules reported in the literature that have telomeric quadruplex stabilizing properties, and assesses the potential for compounds of this type to be developed as novel anticancer therapies. A future perspective is also presented, emphasizing the need for researchers to adopt approaches that will allow the discovery of molecules with more drug-like properties in order to improve the chances of lead molecules reaching the clinic in the next decade.

Design of a novel theranostic nanomedicine: synthesis and physicochemical properties of a biocompatible polyphosphazene-platinum(II) conjugate

To develop a theranostic nanomedicine involving the antitumor-active moiety (dach)Pt(II) (dach: trans-(±)-1,2-diaminocyclohexane) of oxaliplatin (OX), a new biocompatible polyphosphazene carrier polymer was designed by grafting with a methoxy poly(ethylene glycol) (MPEG) to increase duration of circulation in the blood and with aminoethanol (AE) as a spacer group. The antitumor (dach)Pt moiety was conjugated to the carrier polymer using cis-aconitic acid (AA) as a linker, resulting in a polymer conjugate formulated as [NP(MPEG550)(AE-AA)Pt(dach)]_n, named “Polyplatin” (PP). PP was found to self-assemble into very stable polymeric nanoparticles with a mean diameter of 55.1 nm and a critical aggregation concentration of 18.5 mg/L in saline. PP could easily be labeled with a fluorescence dye such as Cy5.5 for imaging studies. The time-dependent ex vivo image studies on organ distributions and clearance of Cy-labeled PP have shown that PP accumulated in the tumor with high selectivity by the enhanced permeability and retention effect but was cleared out from all the major organs including the liver in about 4 weeks postinjection. Another time-dependent bioimaging study on distribution and clearance of PP in mouse kidney using laser ablation inductively coupled plasma mass spectroscopy has shown that PP accumulates much less in kidney and is more rapidly excreted than monomeric OX, which is in accord with the very low acute toxicity of PP as shown by its high LD₅₀ value of more than 2000 mg/kg. The pharmacokinetic study of PP has shown that it has a much longer half-life (t_1/2β) of 13.3 hours compared with the 5.21 hours of OX and about a 20 times higher area under the curve value of 42,850.8 ng h/mL compared with the 2,320.4 ng h/mL of OX. The nude mouse xenograft trials of PP against the gastric MKN-28 tumor cell line exhibited remarkably better tumor efficacy compared with OX at the higher tolerated dose, with lower systemic toxicity.

ER maleate is a novel anticancer agent in oral cancer: implications for cancer therapy

ER maleate [10-(3-Aminopropyl)-3, 4-dimethyl-9(10H)-acridinone maleate] identified in a kinome screen was investigated as a novel anticancer agent for oral squamous cell carcinoma (OSCC). Our aim was to demonstrate its anticancer effects, identify putative molecular targets and determine their clinical relevance and investigate its chemosensitization potential for platinum drugs to aid in OSCC management. Biologic effects of ER maleate were determined using oral cancer cell lines in vitro and oral tumor xenografts in vivo. mRNA profiling, real time PCR and western blot revealed ER maleate modulated the expression of polo-like kinase 1 (PLK1) and spleen tyrosine kinase (Syk). Their clinical significance was determined in oral SCC patients by immunohistochemistry and correlated with prognosis by Kaplan-Meier survival and multivariate Cox regression analyses. ER maleate induced cell apoptosis, inhibited proliferation, colony formation, migration and invasion in oral cancer cells. Imagestream analysis revealed cell cycle arrest in G2/M phase and increased polyploidy, unravelling deregulation of cell division and cell death. Mechanistically, ER maleate decreased expression of PLK1 and Syk, induced cleavage of PARP, caspase9 and caspase3, and increased chemosensitivity to carboplatin; significantly suppressed tumor growth and increased antitumor activity of carboplatin in tumor xenografts. ER maleate treated tumor xenografts showed reduced PLK1 and Syk expression. Clinical investigations revealed overexpression of PLK1 and Syk in oral SCC patients that correlated with disease prognosis. Our in vitro and in vivo findings provide a strong rationale for pre-clinical efficacy of ER maleate as a novel anticancer agent and chemosensitizer of platinum drugs for OSCC.

Comparison of the crystal structures of the potent anticancer and anti-angiogenic agent regorafenib and its monohydrate

Regorafenib {systematic name: 4-[4-({[4-chloro-3-(trifluoromethy)phenyl]carbamoyl}amino)-3-fluorophenoxy]-1-methylpyridine-2-carboxamide}, C21H15ClF4N4O3, is a potent anticancer and anti-angiogenic agent that possesses various activities on the VEGFR, PDGFR, raf and/or flt-3 kinase signaling molecules. The compound has been crystallized as polymorphic form I and as the monohydrate, C21H15ClF4N4O3·H2O. The regorafenib molecule consists of biarylurea and pyridine-2-carboxamide units linked by an ether group. A comparison of both forms shows that they differ in the relative orientation of the biarylurea and pyridine-2-carboxamide units, due to different rotations around the ether group, as measured by the C-O-C bond angles [119.5 (3)° in regorafenib and 116.10 (15)° in the monohydrate]. Meanwhile, the conformational differences are reflected in different hydrogen-bond networks. Polymorphic form I contains two intermolecular N-H...O hydrogen bonds, which link the regorafenib molecules into an infinite molecular chain along the b axis. In the monohydrate, the presence of the solvent water molecule results in more abundant hydrogen bonds. The water molecules act as donors and acceptors, forming N-H...O and O-H...O hydrogen-bond interactions. Thus, R4(2)(28) ring motifs are formed, which are fused to form continuous spiral ring motifs along the a axis. The (trifluoromethyl)phenyl rings protrude on the outside of these motifs and interdigitate with those of adjacent ring motifs, thereby forming columns populated by halogen atoms.

Mode of action and resistance studies unveil new roles for tropodithietic acid as an anticancer agent and the γ-glutamyl cycle as a proton sink

While we have come to appreciate the architectural complexity of microbially synthesized secondary metabolites, far less attention has been paid to linking their structural features with possible modes of action. This is certainly the case with tropodithietic acid (TDA), a broad-spectrum antibiotic generated by marine bacteria that engage in dynamic symbioses with microscopic algae. TDA promotes algal health by killing unwanted marine pathogens; however, its mode of action (MoA) and significance for the survival of an algal-bacterial miniecosystem remains unknown. Using cytological profiling, we herein determine the MoA of TDA and surprisingly find that it acts by a mechanism similar to polyether antibiotics, which are structurally highly divergent. We show that like polyether drugs, TDA collapses the proton motive force by a proton antiport mechanism, in which extracellular protons are exchanged for cytoplasmic cations. The α-carboxy-tropone substructure is ideal for this purpose as the proton can be carried on the carboxyl group, whereas the basicity of the tropylium ion facilitates cation export. Based on similarities to polyether anticancer agents we have further examined TDA's cytotoxicity and find it to exhibit potent, broad-spectrum anticancer activities. These results highlight the power of MoA-profiling technologies in repurposing old drugs for new targets. In addition, we identify an operon that confers TDA resistance to the producing marine bacteria. Bioinformatic and biochemical analyses of these genes lead to a previously unknown metabolic link between TDA/acid resistance and the γ-glutamyl cycle. The implications of this resistance mechanism in the context of the algal-bacterial symbiosis are discussed.

Discovery of a Direct Ras Inhibitor by Screening a Combinatorial Library of Cell-Permeable Bicyclic Peptides

Cyclic peptides have great potential as therapeutic agents and research tools. However, their applications against intracellular targets have been limited, because cyclic peptides are generally impermeable to the cell membrane. It was previously shown that fusion of cyclic peptides with a cyclic cell-penetrating peptide resulted in cell-permeable bicyclic peptides that are proteolytically stable and biologically active in cellular assays. In this work, we tested the generality of the bicyclic approach by synthesizing a combinatorial library of 5.7 × 10⁶ bicyclic peptides featuring a degenerate sequence in the first ring and an invariant cell-penetrating peptide in the second ring. Screening of the library against oncoprotein K-Ras G12V followed by hit optimization produced a moderately potent and cell-permeable K-Ras inhibitor, which physically blocks the Ras-effector interactions in vitro, inhibits the signaling events downstream of Ras in cancer cells, and induces apoptosis of the cancer cells. Our approach should be generally applicable to developing cell-permeable bicyclic peptide inhibitors against other intracellular proteins.

2-Deoxyglucose conjugated platinum (II) complexes for targeted therapy: design, synthesis, and antitumor activity

Malignant neoplasms exhibit an elevated rate of glycolysis over normal cells. To target the Warburg effect, we designed a new series of 2-deoxyglucose (2-DG) conjugated platinum (II) complexes for glucose transporter 1 (GLUT1)-mediated anticancer drug delivery. The potential GLUT1 transportability of the complexes was investigated through a comparative molecular docking analysis utilizing the latest GLUT1 protein crystal structure. The key binding site for 2-DG as GLUT1's substrate was identified with molecular dynamics simulation, and the docking study demonstrated that the 2-DG conjugated platinum (II) complexes can be recognized by the same binding site as potential GLUT1 substrate. The conjugates were synthesized and evaluated for in vitro cytotoxicity study with seven human cancer cell lines. The results of this study revealed that 2-DG conjugated platinum (II) complexes are GLUT1 transportable substrates and exhibit improved cytotoxicities in cancer cell lines that over express GLUT1 when compared to the clinical drug, Oxaliplatin. The correlation between GLUT1 expression and antitumor effects are also confirmed. The study provides fundamental information supporting the potential of the 2-DG conjugated platinum (II) complexes as lead compounds for further pharmaceutical R&D.

Nanofabrication of methylglyoxal with chitosan biopolymer: a potential tool for enhancement of its anticancer effect

Purpose

The normal metabolite methylglyoxal (MG) specifically kills cancer cells by inhibiting glycolysis and mitochondrial respiration without much adverse effect upon normal cells. Though the anticancer property of MG is well documented, its gradual enzymatic degradation in vivo has prompted interest in developing a nanoparticulate drug delivery system to protect it and also to enhance its efficacy.

Materials and methods

MG-conjugated chitosan nanoparticles (Nano-MG) were prepared by conjugating the carbonyl group of MG with the amino group of chitosan polymer (Schiff’s base formation). Nano-MG were characterized in detail using the dynamic light scattering method, zeta potential measurement, Fourier transform infrared spectroscopy, and transmission electron microscopic analysis. Amount of MG anchored to Nano-MG, stability of Nano-MG, and in vitro release of MG from Nano-MG were estimated spectrophotometrically. Ehrlich ascites carcinoma (EAC) cells, human breast cancer cell line HBL-100, and lung epithelial adenocarcinoma cell line A549 were used as test systems to compare Nano-MG with bare MG in vitro. Cytotoxicity to EAC cells was evaluated by the trypan blue dye exclusion test, and cell viability of HBL-100 and A549 cells were studied using 3-(4,5-dimethylthiazol-2-yl) 2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis of HBL-100 cells was assessed by flow cytometry and confocal microscopy. In vivo studies were performed on both EAC cells inoculated and also in sarcoma-180-induced solid tumor-bearing Swiss albino mice to assess the anticancer activity of Nano-MG in comparison to bare MG with varying doses, times, and administrative routes.

Results

Fourier transform infrared spectroscopy revealed the presence of imine groups in Nano-MG due to conjugation of the amino group of chitosan and carbonyl group of MG with diameters of nanoparticles ranging from 50–100 nm. The zeta potential of Nano-MG was +21 mV and they contained approximately 100 μg of MG in 1 mL of solution. In vitro studies with Nano-MG showed higher cytotoxicity and enhanced rate of apoptosis in the HBL-100 cell line in comparison with bare MG, but no detrimental effect on normal mouse myoblast cell line C2C12 at the concerned doses. Studies with EAC cells also showed increased cell death of nearly 1.5 times. Nano-MG had similar cytotoxic effects on A549 cells. In vivo studies further demonstrated the efficacy of Nano-MG over bare MG and found them to be about 400 times more potent in EAC-bearing mice and nearly 80 times more effective in sarcoma-180-bearing mice. Administration of ascorbic acid and creatine during in vivo treatments augmented the anticancer effect of Nano-MG.

Conclusion

The results clearly indicate that Nano-MG may constitute a promising tool in anticancer therapeutics in the near future.

Switch in Site of Inhibition: A Strategy for Structure-Based Discovery of Human Topoisomerase IIα Catalytic Inhibitors

A study of structure-based modulation of known ligands of hTopoIIα, an important enzyme involved in DNA processes, coupled with synthesis and in vitro assays led to the establishment of a strategy of rational switch in mode of inhibition of the enzyme's catalytic cycle. 6-Arylated derivatives of known imidazopyridine ligands were found to be selective inhibitors of hTopoIIα, while not showing TopoI inhibition and DNA binding. Interestingly, while the parent imidazopyridines acted as ATP-competitive inhibitors, arylated derivatives inhibited DNA cleavage similar to merbarone, indicating a switch in mode of inhibition from ATP-hydrolysis to the DNA-cleavage stage of catalytic cycle of the enzyme. The 6-aryl-imidazopyridines were relatively more cytotoxic than etoposide in cancer cells and less toxic to normal cells. Such unprecedented strategy will encourage research on "choice-based change" in target-specific mode of action for rapid drug discovery.

Impact of clinical pharmacy services in a hematology/oncology inpatient setting

BACKGROUND/AIM

Clinical pharmacists are contributing to safe medication use by providing comprehensive management to patients and medical staff. However, little is known regarding their impact in oncology. The aim of this study was to document and evaluate the role of clinical pharmacy services in a hematology/oncology department.

PATIENTS AND METHODS

A prospective, descriptive, observational study was carried out from May 2012 to May 2013. Medication reviews concerning hospitalized adult cancer patients were performed twice a week. Medication problems, pharmaceutical interventions and acceptance rate by the oncologists were recorded by a clinical pharmacist.

RESULTS

A total of 4,393 prescriptions (including chemotherapy and support) of 489 adult cancer patients (mean age=63 years) were analyzed. The pharmacist identified 552 drug-related problems (12.6% of the prescriptions) primarily related to anti-infective agents (59.5%). Medication problems included inappropriate medications (20.6%), untreated indications (14.8%), inappropriate administrations (14.1%), underdosing (11.7%), drug-drug interactions (14.3%), lack of monitoring (9.6%), overdosing (8.9%), administration omissions (3.5%) and side-effects (2.5%). Interventions (n=552) led to treatment discontinuation (26.2%), drug dosing adjustments (21.5%), drug additions (16.9%), alternate routes of administration (11.7%), replacement of a drug by another one (10.7%), therapeutic drug monitoring (10.3%) and optimizing administration (2.6%). Most (96%) of the interventions were accepted and implemented by the medical staff.

CONCLUSION

The integration of clinical pharmacy services resulted in drug-specific interventions in 12.6 % of the prescriptions of hospitalized adult patients with cancer. Medication problems mostly concerned anti-infective agents. The intervention acceptance rate by oncologists was high. The outcome of care in the hematology/oncology inpatient setting remains to be measured.

Methyl jasmonate and its potential in cancer therapy

Methyl jasmonate (MeJa) is a naturally occurring hydrophobic oxylipin phytohormone. Early findings obtained from cancer cell lines suggest that MeJa is endowed with anticancer capabilities. It has been recently proposed that MeJa represents a novel agent that exhibits direct and selective actions against tumor cells without affecting normal human cells. In a previous study, I reported that MeJa itself is enough to result in the dysfunction of mitochondria and chloroplasts, as well as to activate cell death program (apoptosis), in the normal protoplasts of Arabidopsis thaliana. Indeed, this also holds true for other living plant systems in which senescence, hypersensitive response and oxidative stress have been found under MeJa action. Therefore, in this addendum to my previous article, I would like to stress that much more attention should be paid to the potential effect(s) of MeJa, or its derivatives, on healthy cells and tissues before it is used for clinical anticancer drugs, whether being used alone or in combination with other agents.

A novel diblock of copolymer of (monomethoxy poly [ethylene glycol]-oleate) with a small hydrophobic fraction to make stable micelles/polymersomes for curcumin delivery to cancer cells

Curcumin is a potent natural anticancer agent, but its effectiveness is limited by properties such as very low solubility, high rate of degradation, and low rate of absorption of its hydrophobic molecules in vivo. To date, various nanocarriers have been used to improve the bioavailability of this hydrophobic biomaterial. This study investigates the encapsulation of curcumin in a novel nanostructure of monomethoxy poly(ethylene glycol)-oleate (mPEG-OA) and its anticancer effect. Tests were done to determine the critical micelle concentration (CMC), encapsulation efficiency, drug-loading efficiency, and cytotoxicity (against U87MG brain carcinoma cells and HFSF-PI3 cells as normal human fibroblasts) of some nanodevice preparations. The results of fluorescence microscopy and cell-cycle analyses indicated that the in vitro bioavailability of the encapsulated curcumin was significantly greater than that of free curcumin. Cytotoxicity evaluations showed that half maximal inhibitory concentrations of free curcumin and curcumin-loaded mPEG-OA for the U87MG cancer cell line were 48 μM and 24 μM, respectively. The Annexin-V-FLUOS assay was used to quantify the apoptotic effect of the prepared nanostructures. Apoptosis induction was observed in a dose-dependent manner after curcumin-loaded mPEG-OA treatments. Two common self-assembling structures, micelles and polymersomes, were observed by atomic force microscopy and dynamic light scattering, and the abundance of each structure was dependent on the concentration of the diblock copolymer. The mPEG-OA micelles had a very low CMC (13.24 μM or 0.03 g/L). Moreover, atomic force microscopy and dynamic light scattering showed that the curcumin-loaded mPEG-OA polymersomes had very stable structures, and at concentrations 1,000 times less than the CMC, at which the micelles disappear, polymersomes were the dominant structures in the dispersion with a reduced size distribution below 150 nm. Overall, the results from these tests revealed that this nanocarrier can be considered as an appropriate drug delivery system for delivering curcumin to cancer cells.

Relationship between progression-free survival and overall survival in patients with advanced non-small cell lung cancer treated with anticancer agents after first-line treatment failure

AIM

The hazard ratio of progression-free survival (PFS-HR) generally does not reflect that of overall survival (OS-HR) in advanced non-small cell lung cancer (NSCLC) patients treated with first-line therapy. Short survival post-progression (SPP) better reflects the PFS-HR and OS-HR in simulations. We aimed to evaluate whether the PFS-HR reflects the OS-HR in NSCLC clinical trials for post-first-line treatments.

METHOD

We reviewed clinical studies of post-first-line anticancer agents for NSCLC. We examined the sample size of the experimental arm (EA), median PFS (mPFS) or median time to progression in the EA, median overall survival (mOS) in the EA, the PFS-HR and the OS-HR. SPP was defined as the difference between mOS and mPFS. The association between mPFS and SPP, mPFS and mOS, and the PFS-HR and OS-HR was tested. We sought for the optimal point of correlation of PFS-HR and OS-HR by every 1 month of SPP.

RESULTS

We identified 32 trials (34 arms). mPFS and mOS were weakly correlated (correlation coefficient [r] = 0.376; P = 0.0286). The PFS-HR and OS-HR were also moderately correlated (r = 0.415; P = 0.015). The maximum r value was 0.770 (SPP < 6 months; P < 0.0001) when we tested the associations between the PFS-HR and OS-HR for SPP using 1-month increments. The estimated regression equation at this point was OS-HR = 0.679 × (PFS-HR) + 0.349.

CONCLUSION

The PFS-HR and OS-HR were strongly correlated in advanced NSCLC patients treated with post-first-line anticancer agents, with a SPP of less than 6 months.

The psymberin story--biological properties and approaches towards total and analogue syntheses

Psymberin is a marine natural product which has attracted a great deal of interest since its isolation: While the highly cytotoxic compound was detected early on as an ingredient in a marine sponge, it took over a decade and 600 additional samples for the structure to eventually be assigned. In the last eight years fascinating synthetic and biosynthetic investigations have led to a more detailed understanding as well as a new starting point for structure-activity studies towards new antitumor compounds. The Review gives an in-depth insight into the progress in the field of the marine polyketide psymberin and demonstrates how organic synthesis is influencing neighboring scientific subjects.

Design, synthesis and in vitro anticancer evaluation of a stearic acid-based ester conjugate

AIM

Chemical synthesis and characterization of a lipophilic ester conjugate, propofol stearate and evaluation of its anticancer efficacy on human breast cancer cell lines MDA-MB-361, MCF-7 and MDA-MB-231.

MATERIALS AND METHODS

The chemical structure of the synthesized conjugate was characterized by spectroscopic studies. Its anticancer potential was evaluated on the basis of growth inhibition, cancer cell adhesion and migration and apoptosis induction.

RESULTS

Propofol stearate exhibited significant (p<0.05) growth inhibition of breast cancer cells in a concentration-dependent manner. MDA-MB-231 cells showed highest susceptibility towards the inhibitory effect of the conjugate. Moreover, treatment of MDA-MB-231 cancer cells with 25 μM propofol stearate potentially suppressed their adhesion (~34%) and migration (~41%), and induced apoptosis (~25%).

CONCLUSION

Exogenously-applied stearic acid as an ester derivative, inhibits the growth of human breast cancer cells and shows a beneficial role in the treatment of breast cancer, in vitro.

Gemcitabine hydrochloride-loaded functionalised carbon nanotubes as potential carriers for tumour targeting

The objective of the present work was to formulate gemcitabine hydrochloride loaded functionalised carbon nanotubes to achieve tumour targeted drug release and thereby reducing gemcitabine hydrochloride toxicity. Multiwalled carbon nanotubes were functionalised using 1,2-distearoylphosphatidyl ethanolamine-methyl polyethylene glycol conjugate 2000. Optimised ratio 1:2 of carbon nanotubes:1,2-distearoylphosphatidyl ethanolamine-methyl polyethylene glycol conjugate 2000 was taken for loading of gemcitabine hydrochloride. The formulation was evaluated for different parameters. The results showed that maximum drug loading efficiency achieved was 41.59% with an average particle size of 188.7 nm and zeta potential of -10-1 mV. Scanning electron microscopy and transmission electron microscopy images confirmed the tubular structure of the formulation. The carbon nanotubes were able to release gemcitabine hydrochloride faster in acidic pH than at neutral pH indicating its potential for tumour targeting. Gemcitabine hydrochloride release from carbon nanotubes was found to follow Korsmeyer-Peppas kinetic model with non-Fickian diffusion pattern. Cytotoxic activity of formulation on A549 cells was found to be higher in comparison to free gemcitabine hydrochloride. Stability studies indicated that lyophilised samples of the formulation were more stable for 3 months under refrigerated condition than at room temperature. Thus carbon nanotubes can be promising carrier for the anticancer drug gemcitabine hydrochloride.

Synthesis and Biological Evaluation of Novel 3'-Difluorovinyl Taxoids

A series of 3'-difluorovinyl taxoids with C10 modifications, as well as those with C2 and C10 modifications, were strategically designed to block the metabolism by cytochrome P-450 3A4 enzyme and synthesized. These novel difluorovinyl taxoids were evaluated for their cytotoxicity against drug-sensitive human breast (MCF7), multidrug-resistant (MDR) human ovarian (NCI/ADR), human colon (HT-29) and human pancreatic (PANC-1) cancer cell lines. 3'-Difluorovinyl taxoids exhibit several to 16 times better activity against MCF7, HT-29 and PANC-1 cell lines and up to three orders of magnitude higher potency against NCI/ADR cell line as compared to paclitaxel. Structure-activity relationship study shows the critical importance of the C2 modifications on the activity against MDR cancer cell line, while the C10 modifications have a rather minor effect on the potency with some exceptions. The effect of the C2 modifications on potency against MCF7 cell line increases in the following order: H < F < Cl Collapse

Key Words

• anticancer agent
• taxoid
• fluoro-taxoid
• β-lactam synthon method
• difluorovinyl
• baccatin
• structure-activity relationship
• microtubules

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MESH Headings Collapse

Grants

• R01 CA077263 NCI NIH HHS
• R01 CA083185 NCI NIH HHS
• R01 CA103314 NCI NIH HHS

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Affiliation(s)

Larissa Kuznetsova Department of Chemistry, State University of New York at Stony Brook, Stony Brook, NY 11794-3400
Liang Sun Department of Chemistry, State University of New York at Stony Brook, Stony Brook, NY 11794-3400
Jin Chen Department of Chemistry, State University of New York at Stony Brook, Stony Brook, NY 11794-3400
Xianrui Zhao Department of Chemistry, State University of New York at Stony Brook, Stony Brook, NY 11794-3400
Joshua Seitz Department of Chemistry, State University of New York at Stony Brook, Stony Brook, NY 11794-3400
Manisha Das Department of Chemistry, State University of New York at Stony Brook, Stony Brook, NY 11794-3400
Yuan Li Department of Chemistry, State University of New York at Stony Brook, Stony Brook, NY 11794-3400
Jean M. Veith Department of Experimental Therapeutics, Grace Cancer Drug Center, Roswell Park Memorial Institute, Elm and Carlton Streets, Buffalo, New York, 14263
Paula Pera Department of Experimental Therapeutics, Grace Cancer Drug Center, Roswell Park Memorial Institute, Elm and Carlton Streets, Buffalo, New York, 14263
Ralph J. Bernacki Department of Experimental Therapeutics, Grace Cancer Drug Center, Roswell Park Memorial Institute, Elm and Carlton Streets, Buffalo, New York, 14263
Shujun Xia Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461
Susan B. Horwitz Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461
Iwao Ojima Department of Chemistry, State University of New York at Stony Brook, Stony Brook, NY 11794-3400 Institute of Chemical Biology & Drug Discovery, State University of New York at Stony Brook, Stony Brook, NY 11794-3400

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Grafting of a novel gold(III) complex on nanoporous MCM-41 and evaluation of its toxicity in Saccharomyces cerevisiae

The goal of this research was to investigate the potential of newly synthesized gold complex trichloro(2,4,6-trimethylpyridine)Au(III) as an anticancer agent. The gold(III) complex was synthesized and grafted on nanoporous silica, MCM-41, to produce AuCl(3)@PF-MCM- 41 (AuCl(3) grafted on pyridine-functionalized MCM-41). The toxicity of trichloro(2,4,6- trimethylpyridine)Au(III) and AuCl(3)@PF-MCM-41 in Saccharomyces cerevisiae (as a model system) was studied. The gold(III) complex showed a mid cytotoxic effect on yeast viability. Using the drug delivery system, nanoporous MCM-41, the gold(III) complex became a strong inhibitor for growth of yeast cells at a very low concentration. Furthermore, the animal tests revealed a high uptake of AuCl(3)@PF-MCM-41 in tumor cells. The stability of the compound was confirmed in human serum.

Bax-derived membrane-active peptides act as potent and direct inducers of apoptosis in cancer cells

Although many cancer cells are primed for apoptosis, they usually develop resistance to cell death at several levels. Permeabilization of the outer mitochondrial membrane, which is mediated by proapoptotic Bcl-2 family members such as Bax, is considered as a point of no return for initiating apoptotic cell death. This crucial role has placed Bcl-2 family proteins as recurrent targets for anticancer drug development. Here, we propose and demonstrate a new concept based on minimal active versions of Bax to induce cell death independently of endogenous Bcl-2 proteins. We show that membrane-active segments of Bax can directly induce the release of mitochondria-residing apoptogenic factors and commit tumor cells promptly and irreversibly to caspase-dependent apoptosis. On this basis, we designed a peptide encompassing part of the Bax pore-forming domain, which can target mitochondria, induce cytochrome c release and trigger caspase-dependent apoptosis. Moreover, this Bax-derived 'poropeptide' produced effective tumor regression after peritumoral injection in a nude mouse xenograft model. Thus, peptides derived from proteins that form pores in the mitochondrial outer membrane represent novel templates for anticancer agents.

Discovery of substituted N'-(2-oxoindolin-3-ylidene)benzohydrazides as new apoptosis inducers using a cell- and caspase-based HTS assay

We report the discovery of a series of substituted N'-(2-oxoindolin-3-ylidene)benzohydrazides as inducers of apoptosis using our proprietary cell- and caspase-based ASAP HTS assay. Through SAR studies, N'-(4-bromo-5-methyl-2-oxoindolin-3-ylidene)-3,4,5-trimethoxybenzohydrazide (3g) was identified as a potent apoptosis inducer with an EC(50) value of 0.24microM in human colorectal carcinoma HCT116 cells, more than a 40-fold increase in potency from the initial screening hit N'-(5-bromo-2-oxoindolin-3-ylidene)-3,4,5-trimethoxybenzohydrazide (2a). Compound 3g also was found to be highly active in a growth inhibition assay with a GI(50) value of 0.056microM in HCT116 cells. A group of potentially more aqueous soluble analogs were prepared and found to be highly active. Among them, compound 4e incorporating a methyl piperazine moiety was found to have EC(50) values of 0.17, 0.088 and 0.14microM in human colorectal carcinoma cells HCT116, hepatocellular carcinoma cancer SNU398 cells and human colon cancer RKO cells, respectively. Compounds 3g and 4e were found to function as inhibitors of tubulin polymerization.

Structure-activity studies on the lycorine pharmacophore: A potent inducer of apoptosis in human leukemia cells

The direct chemoselective differential functionalization of the ring-C hydroxyl groups present in the Amaryllidaceae alkaloid lycorine is described allowing for selective manipulation of the 1,2-hydroxyl groups. A mini-library comprised of synthetic and natural lycorane alkaloids was prepared and their apoptosis-inducing activity investigated in human leukemia (Jurkat) cells. Further insights into the nature of this interesting apoptosis-inducing pharmacophore are described, including the requirement of both free hydroxyl groups in ring-C.

Nanovectors for anticancer agents based on superparamagnetic iron oxide nanoparticles

During the last decade, the application of nanotechnologies for anticancer drug delivery has been extensively explored, hoping to improve the efficacy and to reduce side effects of chemotherapy. The present review is dedicated to a certain kind of anticancer drug nanovectors developed to target tumors with the help of an external magnetic field. More particularly, this work treats anticancer drug nanoformulations based on superparamagnetic iron oxide nanoparticles coated with biocompatible polymers. The major purpose is to focus on the specific requirements and technological difficulties related to controlled delivery of antitumoral agents. We attempt to state the problem and its possible perspectives by considering the three major constituents of the magnetic therapeutic vectors: iron oxide nanoparticles, polymeric coating and anticancer drug.

An overview on the development of newcastle disease virus as an anti-cancer therapy

Newcastle disease virus (NDV) is one of the most economically important avian virus which affects the poultry industry worldwide. Although NDV is being very actively studied in Malaysia, there are still no studies on its potential as an anticancer agent, a new approach to treating cancer known as virotherapy. Currently, a collaborative research is being undertaken between Universiti Putra Malaysia (UPM), Universiti Sains Malaysia (USM) and Majlis Kanser Nasional (MAKNA) in characterising various local NDV isolates as anticancer agent. This paper describes an overview of the research that have been carried out worldwide in the use of NDV for cancer treatment and also some of our findings in characterising local NDVs with oncolytic properties.

Evaluation of the relative cytotoxic effects of anticancer agents in serum-supplemented versus serum-free media using a tetrazolium colorimetric assay

Most cell culture and in vitro drug sensitivity assays utilize serum-supplemented media (SSM). However, fully defined serum-free media (SFM) offer several advantages and are being used increasingly for initiation and maintenance of cell cultures. Because serum inhibits the in vitro cytotoxicity of certain antineoplastic agents, we investigated the inter-relationships between medium type, cell proliferation and cytotoxic effect. Twenty-four human lung cancer cell lines were tested with nine anticancer agents in both media types. A semi-automated tetrazolium (MTT) colorimetric assay was used for assaying cell survival. Cell lines initiated and maintained in SFM preferentially proliferated in that medium type or proliferated equally well in both media types. In contrast, cell lines established in SSM varied considerably in their medium of preference. There appeared to be a direct correlation or trend between cell proliferative rate and cytotoxicity of all drugs with the possible exceptions of methotrexate and carmustine. In general, the cell lines were more sensitive to anticancer agents when they were exposed in the culture medium in which they preferentially proliferated. Therefore, to determine the influence of culture media on cytotoxicity, we analyzed the data only from lines that replicated equally efficiently in both media. After correction for cell proliferative rate, SSM had a negative effect on the cytotoxic action of some drugs (especially methotrexate, 5-fluorouracil and, to a lesser extent, mitomycin-C). Our results demonstrate that fully defined SFM may be suitable for initiating cell lines and for use in in vitro cytotoxicity assays for selection of individualized therapy or for screening of new anti-neoplastic agents, and thus may increase the number of antineoplastic agents that can be tested satisfactorily.

Stereo (C7)-dependent topoisomerase II inhibition and tumor growth suppression by a new quinolone, BO-2367

A new antimicrobial quinolone (-)BO-2367, (-)-7-[(1R*, 2R*, 6R*)-2-amino-8-azabicyclo[4.3.0.]-non-3-en-8-yl]-1- cyclopropyl-6,8-difluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid, strongly inhibited both mammalian and bacterial topoisomerase II. The IC50 values of (-)BO-2367 against the DNA relaxation activity of L1210 topoisomerase II and the supercoiling activities of Escherichia coli gyrase and Micrococcus luteus gyrase were 3.8, 0.5, and 1 microM, respectively. This compound enhanced double-stranded DNA cleavage mediated by topoisomerase II not only with purified enzyme, but also with intact L1210 cells. All these activities of (-)BO-2367 were more than 2-fold stronger than those of VP-16. Intriguingly, (+)BO-2367, which has an enantiomeric substituent at the C7 position of (-)BO-2367, did not affect the activity of the mammalian topoisomerase II, while it inhibited E. coli gyrase. Intraperitoneal injection of (-)BO-2367 at 0.08 mg/kg increased the lifespan of CDF1 female mice bearing ascitic L1210 leukemia by 2.4 times, and subcutaneous injection at 1.25 mg/kg completely inhibited the growth of colon 26 carcinoma implanted subcutaneously. These results suggest that (-)BO-2367 is a potent antitumor agent which targets topoisomerase II. These enantiomers should be a useful tool for studying drug-topoisomerase II interactions.

Inhibitory effects of sizofiran on anticancer agent- or X-ray-induced sister chromatid exchanges and mitotic block in murine bone marrow cells

The inhibitory effects of a biological response modifier (BRM), sizofiran, on sister chromatid exchanges (SCEs) in the bone marrow cells of mice treated with various anticancer agents or irradiation were investigated. Sizofiran (10 mg/kg i.m.) inhibited SCEs induced by mitomycin C (2 mg/kg i.v.), adriamycin (20 mg/kg i.v.) and cyclophosphamide (20 mg/kg i.v.) by about 20%, respectively. Analysis of the SCEs in vivo after irradiation plus sizofiran indicated that SCE levels were significantly lower than those observed in mice exposed to irradiation without sizofiran. Moreover, the effects of sizofiran were dependent on the timing of administration. Our results indicated that sizofiran should be administered simultaneously or soon after irradiation in order to minimize damage. Sizofiran also markedly restored the bone marrow cell mitosis which had been suppressed by anticancer agents, and this action was closely correlated with the prevention of increase in SCEs. These results indicate that in addition to immunopotentiating activity, sizofiran may play a role in preventing chromosomal damage induced by cancer chemotherapy and radiotherapy.

Effect of anticancer agents neothramycin, aclacinomycin, FK-565 and FK-156 on the release of interleukin-2 and interleukin-1 in vitro

Four anticancer agents, neothramycin, aclacinomycin, FK-565 and FK-156, were tested for their effects on concanavalin-A-induced interleukin-2 release from rat splenocytes in vitro. Neothramycin showed an enhancement of the release of interleukin-2, whereas aclacinomycin had no effect. FK-565 and FK-156 were found to inhibit the release of interleukin-2 under similar conditions. The inhibition was much more marked with FK-565. These drugs were also tested for their effects on the release of interleukin-1 from rat peritoneal exudate cells stimulated by lipopolysaccharide in vitro. Neothramycin and aclacinomycin did not affect the release of interleukin-1; however, both FK-565 and FK-156 resulted in its enhanced release under these conditions.