Overexpression of ABCC1 and ABCG2 confers resistance to talazoparib, a poly (ADP-Ribose) polymerase inhibitor.

AIMS: The overexpression of ABC transporters on cancer cell membranes is one of the most common causes of multidrug resistance (MDR). This study investigates the impact of ABCC1 and ABCG2 on the resistance to talazoparib (BMN-673), a potent poly (ADP-ribose) polymerase (PARP) inhibitor, in ovarian cancer treatment. METHODS: The cell viability test was used to indicate the effect of talazoparib in different cell lines. Computational molecular docking analysis was conducted to simulate the interaction between talazoparib and ABCC1 or ABCG2. The mechanism of talazoparib resistance was investigated by constructing talazoparib-resistant subline A2780/T4 from A2780 through drug selection with gradually increasing talazoparib concentration. RESULTS: Talazoparib cytotoxicity decreased in drug-selected or gene-transfected cell lines overexpressing ABCC1 or ABCG2 but can be restored by ABCC1 or ABCG2 inhibitors. Talazoparib competitively inhibited substrate drug efflux activity of ABCC1 or ABCG2. Upregulated ABCC1 and ABCG2 protein expression on the plasma membrane of A2780/T4 cells enhances resistance to other substrate drugs, which could be overcome by the knockout of either gene. In vivo experiments confirmed the retention of drug-resistant characteristics in tumor xenograft mouse models. CONCLUSIONS: The therapeutic efficacy of talazoparib in cancer may be compromised by its susceptibility to MDR, which is attributed to its interactions with the ABCC1 or ABCG2 transporters. The overexpression of these transporters can potentially diminish the therapeutic impact of talazoparib in cancer treatment.

Development of an Arginine Anchored Nanoglobule with Retrograde Trafficking Inhibitor (Retro-2) for the Treatment of an Enterohemorrhagic Escherichia coli Outbreak.

Enterohemorrhagic Escherichia coli O157:H7 (EHEC) or Shiga toxin-producing E. coli (STEC) is known to cause sporadic and epidemic gastrointestinal infections with several incidences of outbreaks. Antibiotic-based therapy further worsens the condition by facilitating the release of Shiga toxins (Stx) and lipopolysaccharides (LPS). Hence, there is an urgent need to develop an antibiotic-free, safe, and effective therapeutic intervention for the treatment of EHEC infections. We proposed a novel therapeutic strategy to address this clinical problem-kill, capture, and inhibit. We aimed to formulate and characterize lauroyl arginate ethyl ester (LAE) and Retro-2 loaded self-nano emulsifying drug delivery systems (SNEDDS). Retro-2 is a recently developed novel class of molecule, which can selectively inhibit retrograde transport of Stx. In this paper, we first carried out preformulation studies of Retro-2, followed by the development of SNEDDS forming arginine anchored nanoglobules (AR-NG), characterization of LPS binding to AR-NG, and finally evaluation of activity against EHEC. Retro-2 showed extremely poor solubility at all gastrointestinal pH values, susceptibility to acidic environments, and good permeability. The positively charged AR-NG spontaneously formed a globule size of 102.8 ± 1.9 nm with a surface charge of +52.15 ± 3 mV and increased the solubility of Retro-2. Further, binding and aggregation of LPS and AR-NG were confirmed by particle size, polydispersity index, zeta potential, fluorescent intensity, turbidity analysis, and a limulus amebocyte lysate (LAL) test. Additionally, a significant reduction in LPS induced TNF-α was observed in AR-NG treated macrophages. Thus, in this paper, we demonstrate a very promising and innovative therapeutic approach based on the "kill (E. Coli), capture (released LPS), and inhibit (transport of Stx)" concept.

Ciprofloxacin Enhances the Chemosensitivity of Cancer Cells to ABCB1 Substrates.

ABCB1 is one of the major drug efflux transporters that is known to cause multidrug resistance (MDR) in cancer patients receiving chemotherapy for the treatment of solid tumors and hematological malignancies. Inhibition of ABCB1 efflux function is important for maintaining the intracellular concentration of chemotherapeutic drugs. Here, we evaluated ciprofloxacin for its ability to reverse MDR caused by the overexpression of ABCB1. Cytotoxicity of ciprofloxacin was determined by the MTT assay. The chemosensitizing effects of ciprofloxacin were determined in combination with ABCB1 substrates. The intracellular accumulation and efflux of ABCB1 substrates was measured by a scintillation counter, and protein expression was determined by the Western blotting. Vanadate-sensitive ATPase assay was performed to determine the effect of ciprofloxacin on the ATPase activity of ABCB1, and docking analysis was done to determine the interaction of ciprofloxacin with ABCB1. Ciprofloxacin significantly potentiated the cytotoxic effects of ABCB1 substrates in ABCB1-overexpressing cells. Furthermore, ciprofloxacin increased the intracellular accumulation and decreased the efflux of [³H]-paclitaxel without altering the expression of ABCB1. Ciprofloxacin stimulated the ATPase activity of ABCB1 in a concentration-dependent manner. Our findings showed that ciprofloxacin potently inhibits the ABCB1 efflux function and it has potential to be developed as a combination anticancer therapy.

Synthesis of N-1', N-3'-disubstituted spirohydantoins and their anticonvulsant activities in pilocarpine model of temporal lobe epilepsy.

Herein we report the synthesis and anticonvulsant activity of a library of eighteen new compounds that are structural mimics of phenytoin. These class of compounds contain a N-1', N-3'-disubstituted spirohydantoin scaffold, where the N-1' and N-3' positions are modified with an alkyl group or aryl group. Of the eighteen compounds synthesized and tested, compound 5c showed the best anticonvulsant activity. It completely prevented the precursor events of motor seizure in the pilocarpine model of temporal lobe epilepsy. Additionally, ten of the analogs were more effective than phenytoin when compared using the Racine's score in the pilocarpine model. Based on the structure activity relationship (SAR), we concluded that alkyl groups (ethyl, propyl or cyclopropyl) at N-3' position and 4-nitro phenyl group at N-1' position are desirable.

Chemical Derivatization Leads to the Discovery Of Novel Analogs of Azotochelin, a Natural Siderophore, as Promising Anticancer Agents.

Siderophores are structurally unique medicinal natural products and exhibit considerable therapeutic potential. Herein, we report the design and synthesis of azotochelin, a natural siderophore, and an extensive library of azotochelin analogs and their anticancer properties. We modified the carboxylic acid and the aromatic ring of azotochelin using various chemical motifs. We evaluated the cytotoxicity of the compounds against six different cancer cell lines (KB-3-1, SNB-19, MCF-7, K-562, SW-620, and NCI-H460) and a non-cancerous cell line (HEK-293). Among the twenty compounds tested, the IC50 values of nine compounds (14, 32, 35-40, and 54) were between 0.7 and 2.0 µM against a lung cancer cell line (NCI-H460). Moreover, several compounds showed good cytotoxicity profile (IC50 <10 µM) against the tested cancer cell lines. The flow cytometry analysis showed that compounds 36 and 38 induced apoptosis in NCI-H460 in a dose-dependent manner. The cell cycle analysis indicated that compounds 36 and 38 significantly arrested the cell cycle at the S phase to block cancer cell proliferation in the NCI-H460 cell line. The study has produced various novel azotochelin analogs that are potentially effective anticancer agents and lead compounds for further synthetic and medicinal chemistry exploration.

An efficient chemical synthesis of carboxylate-isostere analogs of daptomycin.

Herein we report a direct and efficient method for the synthesis of four new carboxylate-isostere analogs of daptomycin. The side chain carboxylic acid moieties of the aspartic acids (Asp-3, Asp-7 and Asp-9) and ß-methyl glutamic acid (MeGlu-12) were all converted into the corresponding carboxylate isosteres using direct synthetic procedures. The present study also describes an esterification protocol to overcome the possible backbone cyclization of the activated side chain carboxylic acid group of either Asp or Glu onto the backbone amide.

Novel Indolyl-Benzimidazole Compounds Promote in vitro Wound Healing and Osteogenic Differentiation of Pluripotent Cells.

BACKGROUND: Increasing or restoring Bone Morphogenetic Protein- (BMP-) signaling through administration of recombinant BMPs (rBMPs) has demonstrated therapeutic efficacy for treating bone fractures or to enhance repair following spinal surgeries. However, direct use of rBMPs has come up against significant obstacles like high cost and incidence of adverse effects. Recently, we reported our findings on the novel indolyl-benzimidazoles, SY-LB-35 and SY-LB-57, that fully activated BMP receptor signaling demonstrating activity profiles that mirrored rBMPs. Here, we explored the potential of these compounds to substitute for rBMPs in processes like wound healing and osteogenesis. METHODS: Cell-based assays including cell viability, short- and long-term phosphorylation, protein expression, wound healing and bone differentiation assays were carried out in the pluripotent myoblast C2C12 cell line with select assays performed in multiple cell lines. Several assays included conditions in the presence of a selective inhibitor of type I BMP receptor, Activin-like kinase 2 (ALK2), or inhibitors of BMP-stimulated downstream signaling. All assays were repeated at least 3 times with replicates per condition where indicated. Statistical tests were carried out using Student's two-tailed, t-test. RESULTS: Sustained activation of non-canonical BMP signaling pathways was observed after 24-hour exposure to SY-LB-35 and SY-LB-57. Moreover, this treatment increased the expression of targets of BMP-mediated transcription such as the Id1 transcription factor. SY-LB-35 and SY-LB-57 promoted substantial increases in cell viability in three distinct cell types and increased the rate of wound closure in scrape-wounded C2C12 cell cultures. Cell viability and wound closure induced by SY-LB compounds required ALK2-, PI3K- and p38-dependent pathways. In contrast, responses to SY-LB compounds were not affected by ERK inhibition. Expression of bone differentiation markers beginning at 4 hours and evidence of calcium deposition detected after 21 days in C2C12 cell cultures exposed to SY-LB-35 and SY-LB-57 demonstrated the osteogenic potential of these compounds. CONCLUSIONS: The functional similarities between these novel compounds and rBMPs indicates that SY-LB-35 or SY-LB-57, acting as potent activators of BMP receptor signaling and inducers of osteogenic processes, could potentially replace rBMPs for treating BMP-related pathologies such as bone fracture repair or other wound healing processes.

Biosynthesis of aminovinyl-cysteine-containing peptides and its application in the production of potential drug candidates.

Bacteria produce a wide array of metabolites to protect themselves from competing microbes. These antimicrobial compounds include peptides with an S-[(Z)-2-aminovinyl]-d-cysteine (AviCys) or S-[(Z)-2-aminovinyl]-(3S)-3-methyl-d-cysteine (AviMeCys) residue, which have been isolated from several different bacterial species. The peptides are structurally diverse: some feature polycyclic backbones, such as the lantibiotic epidermin, and others feature a mostly linear structure, such as cypemycin. Each of the AviCys-containing peptides characterized to date exhibit highly potent biological activities, ranging from antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA) to anticancer activity against mouse leukemia cells. The AviCys-containing peptides gallidermin and mutacin 1140 have been suggested as possible treatments of acne and of throat infections, respectively. Unfortunately, their low production yield in fermentation (typically only 10-200 mg/L) remains a major hindrance to the widespread use and clinical testing of AviCys-containing peptides for human therapeutics. Although scientists have made great strides in the total chemical synthesis of polycyclic peptides on solid support, an efficient method to form the AviCys ring has yet to be developed. In light of these difficulties, it may be possible to draw inspiration from the natural biosynthesis of AviCys-containing peptides within the producer organisms. In this Account, we examine the characteristics of the enzymes responsible for constructing AviCys to evaluate possibilities for generating high yields of bioactive AviCys- or AviMeCys-containing peptides for research and clinical use. The gene cluster for the biosynthesis of epidermin has been studied in depth, leading to the proposal for a mechanism of AviCys formation. First, a serine residue upstream of the C-terminus is enzymatically dehydrated to form a dehydroalanine residue. Then, the C-terminal cysteine residue is oxidatively decarboxylated to form an enethiolate, which subsequently cyclizes onto the dehydroalanine to give the AviCys ring. Extensive research on EpiD, the enzyme responsible for the oxidative decarboxylation reaction, has led to its purification and cocrystallization with a model substrate peptide, yielding an X-ray crystal structure. An in vitro assay of the enzyme with a library of synthetic heptapeptides has resulted in the discovery that EpiD has low absolute substrate specificity and can oxidatively decarboxylate a wide variety of C-terminal cysteine-containing peptides. Recently, the gene cluster for the biosynthesis of cypemycin was also identified. Despite certain structural similarities between cypemycin and the lantibiotic peptides, analysis of the biosynthetic genes suggests that cypemycin production is quite different from that of the lantibiotics. In particular, the AviCys residue in cypemycin is formed from two cysteine residues instead of one serine and one cysteine, and the CypD enzyme that catalyzes the oxidative decarboxylation of the C-terminal cysteine shows little homology to EpiD. The knowledge accrued from studying EpiD and CypD could be used to develop a semisynthetic methodology to produce AviCys-containing peptides. In particular, suitable precursor peptides could be synthesized on solid support before being fed to either of these enzymes in vitro to generate the C-terminal AviCys moiety. Exploring the potential of this methodology could lead to the efficient production of epidermin, cypemycin, and analogues thereof.

Discovery of a novel class of benzimidazoles as highly effective agonists of bone morphogenetic protein (BMP) receptor signaling.

Increasing or restoring Bone Morphogenetic Protein receptor signaling is an effective therapy for conditions such as bone fracture and pulmonary arterial hypertension. However, direct use of recombinant BMPs has encountered significant obstacles. Moreover, synthetic, full agonists of BMP receptor signaling have yet to be identified. Here, we report the discovery of a novel class of indolyl-benzimidazoles, synthesized using a one-pot synthetic methodology, which appear to mimic the biochemical and functional activity of BMPs. The first-in-series compounds, SY-LB-35 and SY-LB-57, stimulated significant increases in cell number and cell viability in the C2C12 myoblast cell line. Cell cycle analysis revealed that these compounds induced a shift toward proliferative phases. SY-LB-35 and SY-LB-57 stimulated canonical Smad and non-canonical PI3K/Akt, ERK, p38 and JNK intracellular signaling pathways, similar to BMP2-stimulated responses. Importantly, increases in Smad phosphorylation and cell viability were dependent on type I BMP receptor activity. Thus, these compounds robustly activate intracellular signaling in a BMP receptor-dependent manner and may signify the first known, full agonists of BMP receptor signaling. Moreover, discovery of small molecule activators of BMP pathways, which can be efficiently formulated and targeted to diseased or damaged areas, could potentially substitute recombinant BMPs for treatment of BMP-related pathologies.

Anticancer effect of Indanone-based thiazolyl hydrazone derivative on p53 mutant colorectal cancer cell lines: An in vitro and in vivo study.

Colorectal cancer is a major health problem, and it is the third most diagnosed cancer in the United States. The current treatment for colorectal cancer includes irinotecan, a topoisomerase I inhibitor, and other targeted drugs, such as bevacizumab and regorafenib. The low response rates and incidence of high toxicity caused by these drugs instigated an evaluation of the anticancer efficacy of a series of 13 thiazolyl hydrazone derivatives of 1-indanone, and four compounds among them show favorable anticancer activity against some of the tested colorectal cancer cell lines with IC50 values ranging from 0.41 ± 0.19 to 6.85 ± 1.44 µM. It is noteworthy that one of the indanone-based thiazolyl hydrazone (ITH) derivatives, N-Indan-1-ylidene-N'-(4-Biphenyl-4-yl-thiazol-2-yl)-hydrazine (ITH-6), has a better cytotoxicity profile against p53 mutant colorectal cancer cells HT-29, COLO 205, and KM 12 than a p53 wild-type colorectal cancer cell line, such as HCT 116. Mechanistic studies show that ITH-6 arrests these three cancer cell lines in the G2/M phase and induces apoptosis. It also causes a rise in the reactive oxygen species level with a remarkable decrease in the glutathione (GSH) level. Moreover, ITH-6 inhibits the expression of NF-κB p65 and Bcl-2, which proves its cytotoxic action. In addition, ITH-6 significantly decreased tumor size, growth rate, and tumor volume in mice bearing HT-29 and KM 12 tumor xenografts. Moreover, CRISPR/Cas9 was applied to establish an NF-κB p65 gene knockout HT-29 cell line model to validate the target of ITH-6. Overall, the results suggest that ITH-6 could be a potential anticancer drug candidate for p53 mutant colorectal cancers.

MET inhibitor tepotinib antagonizes multidrug resistance mediated by ABCG2 transporter: In vitro and in vivo study.

Overexpression of ABCG2 transporter in cancer cells has been linked to the development of multidrug resistance (MDR), an obstacle to cancer therapy. Our recent study uncovered that the MET inhibitor, tepotinib, is a potent reversal agent for ABCB1-mediated MDR. In the present study, we reported for the first time that the MET inhibitor tepotinib can also reverse ABCG2-mediated MDR in vitro and in vivo by directly binding to the drug-binding site of ABCG2 and reversibly inhibiting ABCG2 drug efflux activity, therefore enhancing the cytotoxicity of substrate drugs in drug-resistant cancer cells. Furthermore, the ABCB1/ABCG2 double-transfected cell model and ABCG2 gene knockout cell model demonstrated that tepotinib specifically inhibits the two MDR transporters. In mice bearing drug-resistant tumors, tepotinib increased the intratumoral accumulation of ABCG2 substrate drug topotecan and enhanced its antitumor effect. Therefore, our study provides a new potential of repositioning tepotinib as an ABCG2 inhibitor and combining tepotinib with substrate drugs to antagonize ABCG2-mediated MDR.

Chemical synthesis and biological evaluation of gallidermin-siderophore conjugates.

The lantibiotic gallidermin was modified at lysine residues by regioselective attachment of derivatives of pyochelin, agrobactin and desferrioxamine B with the objective of having siderophore receptors of Gram-negative bacteria transport the antibiotic-iron chelator conjugate through the outer membrane. All of the conjugates retained activity against the Gram-positive indicator strain, Lactococcus lactis subsp. cremoris HP. However, testing of the conjugates against several Gram-negative strains yielded unexpected results. Bacteria treated with 100 µM of the conjugates complexed with Fe(3+) grew better than bacteria grown in iron-free media but worse than bacteria grown in the same media supplemented with 10 µM FeCl(3). Although these findings indicate that the conjugates are unable to inhibit the growth of Gram-negative bacteria, they indicate penetration of the outer membrane and provide structure-activity information for design of other lantibiotic conjugates. The synthetic strategy is applicable for linking biomarkers or fluorescence probes to gallidermin for studies on its localization and mode of action. As there are many lantibiotics that operate with unknown mechanisms of action, this chemical approach provides a means to modify such peptides with biomarkers for biological investigations.

Ellagic Acid and Schisandrins: Natural Biaryl Polyphenols with Therapeutic Potential to Overcome Multidrug Resistance in Cancer.

Multidrug resistance (MDR) is one of the major clinical challenges in cancer treatment and compromises the effectiveness of conventional anticancer chemotherapeutics. Among known mechanisms of drug resistance, drug efflux via ATP binding cassette (ABC) transporters, namely P-glycoprotein (P-gp) has been characterized as a major mechanism of MDR. The primary function of ABC transporters is to regulate the transport of endogenous and exogenous small molecules across the membrane barrier in various tissues. P-gp and similar efflux pumps are associated with MDR because of their overexpression in many cancer types. One of the intensively studied approaches to overcome this mode of MDR involves development of small molecules to modulate P-gp activity. This strategy improves the sensitivity of cancer cells to anticancer drugs that are otherwise ineffective. Although multiple generations of P-gp inhibitors have been identified to date, reported compounds have demonstrated low clinical efficacy and adverse effects. More recently, natural polyphenols have emerged as a promising class of compounds to address P-gp linked MDR. This review highlights the chemical structure and anticancer activities of selected members of a structurally unique class of 'biaryl' polyphenols. The discussion focuses on the anticancer properties of ellagic acid, ellagic acid derivatives, and schisandrins. Research reports regarding their inherent anticancer activities and their ability to sensitize MDR cell lines towards conventional anticancer drugs are highlighted here. Additionally, a brief discussion about the axial chirality (i.e., atropisomerism) that may be introduced into these natural products for medicinal chemistry studies is also provided.

The Spleen Tyrosine Kinase Inhibitor, Entospletinib (GS-9973) Restores Chemosensitivity in Lung Cancer Cells by Modulating ABCG2-mediated Multidrug Resistance.

Tyrosine kinase inhibitors (TKIs) are important in managing lymphoid malignancies by targeting B-cell receptor signaling pathways. Entospletinib (GS-9973) is an oral, selective inhibitor of spleen tyrosine kinase (Syk), currently in the phase II clinical trials for the treatment of chronic lymphocytic leukemia. Syk is abundantly present in the cells of hematopoietic lineage that mediates cell proliferation, differentiation, and adhesion. In this current study, we evaluated the efficacy of GS-9973 to overcome multidrug resistance (MDR) due to the overexpression of the ABCG2 transporter in the non-small cell lung cancer (NSCLC) cell line, NCI-H460/MX20. In vitro, 3 µM of GS-9973 reversed the drug resistance of NCI-H460/MX20 cell line to mitoxantrone or doxorubicin. GS-9973, at 3 µM reverses ABCG2-mediated MDR by blocking ABCG2 efflux activity and downregulating ABCG2 expression at the protein level but did not alter the ABCG2 mRNA expression and subcellular localization of the ABCG2 protein compared to drug-resistant cells incubated with the vehicle. GS-9973 produced a moderate concentration-dependent increase in the ATPase activity of ABCG2 (EC50 = 0.42 µM) and molecular docking data indicated that GS-9973 had a high affinity (-10.226 kcal/mol) for the substrate-binding site of ABCG2. Finally, HPLC analysis proved that the intracellular concentration of GS-9973 is not significantly different in both parental and resistant cell lines. In conclusion, our study suggests that in vitro, GS-9973 in combination with certain anticancer drugs, represent a strategy to overcome ABCG2-mediated MDR cancers.

Exploration of Antibiotic Activity of Aminoglycosides, in Particular Ribostamycin Alone and in Combination With Ethylenediaminetetraacetic Acid Against Pathogenic Bacteria.

The emergence of infections caused by bacterial pathogens that are resistant to current antibiotic therapy is a critical healthcare challenge. Aminoglycosides are natural antibiotics with broad spectrum of activity; however, their clinical use is limited due to considerable nephrotoxicity. Moreover, drug-resistant bacteria that cause infections in human as well as livestock are less responsive to conventional antibiotics. Herein, we report the in vitro antibacterial evaluation of five different aminoglycosides, including ribostamycin, against a panel of Gram-positive and Gram-negative pathogens. Eight of the tested bacterial strains are linked to gastrointestinal (GI) infections. The minimum inhibitory concentration (MIC) of ribostamycin against three different Escherichia coli strains is in the range of 0.9-7.2 µM and against a strain of Haemophilus influenzae is 0.5 µM. We also found that the MIC of ribostamycin was considerably enhanced from 57.2 to 7.2 µM, an 8-fold improvement, when bacteria were treated with a combination of ribostamycin and ethylenediaminetetraacetic acid (EDTA). These findings demonstrate a promising approach to enhance the clinical potential of ribostamycin and provide a rational for its antibiotic reclassification from special level to non-restricted level.

Preclinical development of a novel BCR-ABL T315I inhibitor against chronic myeloid leukemia.

Chronic Myeloid Leukemia (CML) is a myeloproliferative neoplasm primarily due to the presence of the BCR-ABL fusion gene that produces the constitutively active protein, BCR-ABL. Imatinib, a BCR-ABL-targeted drug, is a first-line drug for the treatment of CML. Resistance to imatinib occurs as a result of mutations in the BCR-ABL kinase domains. In this study, we evaluated S116836, a novel BCR-ABL inhibitor, for its anti-cancer efficacy in the wild-type (WT) and T315I mutant BCR-ABL. S116836 was efficacious in BaF3 cells with WT or T315I mutated BCR-ABL genotypes. S116836 inhibits the phosphorylation of BCR-ABL and its downstream signaling in BaF3/WT and BaF3/T315I cells. Mechanistically, S116836 arrests the cells in the G0/G1 phase of cell cycle, induces apoptosis, increases ROS production, and decreases GSH production in BaF3/WT and BaF3/T315I cells. Moreover, in mouse tumor xenografts, S116836 significantly inhibits the growth and volume of tumors expressing the WT or T315I mutant BCR-ABL without causing significant cardiotoxicity. Overall, our results indicate that S116836 significantly inhibits the imatinib-resistant T315I BCR-ABL mutation and could be a novel drug candidate for treating imatinib-resistant CML patients.

Synthesis and Biological Evaluation of Structurally Diverse Benzimidazole Scaffolds as Potential Chemotherapeutic Agents.

BACKGROUND AND OBJECTIVE: Drug resistance and adverse effects are immense healthcare challenges in cancer therapy. Benzimidazole ring-based small molecules have been effective anticancer agents in drug development. In an effort to develop novel chemotherapeutics, we synthesized and assessed the anticancer and antibacterial activities of a small library of structurally unique benzimidazoles. METHODS: The benzimidazoles were derived from indole, N-alkyl indole, fatty acid, and alpha-amino acid scaffolds providing a panel of diverse structures. The compounds were tested in three different cancer cell lines for cytotoxicity: HepG2 (human hepatocellular carcinoma), HeLa (human cervical carcinoma), and A549 (human lung carcinoma). Mechanism of cell death induced by benzimidazoles was evaluated using fluorescent dye-based apoptosis-necrosis assay, immunoblotting for active caspases, topoisomerase-II activity assay, and cell cycle assay. RESULTS: Cell viability testing revealed that indole- and fatty acid-based benzimidazoles were most potent followed by the amino acid derivatives. Many compounds induced cytotoxicity in a concentration-dependent manner with cellular cytotoxicity (CC50) <20µM in the cell lines tested. Most compounds exhibited cytotoxicity via apoptosis through the intrinsic pathway. Inhibition of topoisomerase activity and cell cycle alterations were not the primary mechanisms of cytotoxicity. In addition, several compounds showed promising activity against S. aureus and S. epidermidis (Minimum Inhibitory Concentration (MIC) of as low as 0.04µmol/mL). CONCLUSION: The reported benzimidazole derivatives possess promising anticancer and antibacterial properties. Additionally, we discovered apoptosis to be the primary mechanism for cancer cell death induced by the tested benzimidazoles. Our findings suggest that further development of these scaffolds could provide drug leads towards new chemotherapeutics.

Fracturing rings to understand lantibiotics.

Haloduracin is a bacterially produced antibiotic system of two alkali-stable peptides (Halalpha and Halbeta) that have extensive posttranslational modifications, including lanthionine rings. Now, Cooper et al. (2008) revise the structure of Halbeta and demonstrate that some of the lanthionine rings are not essential for bioactivity.

Tyrosine kinase inhibitor conjugated quantum dots for non-small cell lung cancer (NSCLC) treatment.

Non-small cell lung cancer is a major sub-type of lung cancer that is associated with a poor diagnosis resulting in poor therapy for the disorder. In order to achieve a better prognosis, innovative multi-functional systems need to be developed which will aide in diagnosis as well as therapy for the disorder. One such multi-functional delivery system fabricated is Quantum Dots (QDs). QDs are photo-luminescent inorganic nanoparticles utilized for tumor detection, preclinically. Erlotinib hydrochloride, a tyrosine kinase inhibitor, is a first-generation drug developed to treat NSCLC. Its active metabolite, Desmethyl Erlotinib (OSI-420), exhibits similar anticancer activity as erlotinib. OSI-420 was conjugated to QDs to fabricate a delivery system and was then characterized by FT-IR, H NMR, UV-VIS, particle size, zeta potential, fluorescence spectroscopy and TEM. Drug loading was estimated using UV-VIS spectroscopy (52.2 ±â€¯7.5%). A concentration-dependent release of OSI-420 was achieved using esterase enzymes, which was further confirmed using LC-MS. A cellular uptake study revealed the internalization potential of QDs and QD-OSI 420. A cellular recovery study was performed to confirm the internalization potential. Cell viability studies revealed that QD-OSI 420 conjugates had significantly better efficacy than pure drugs in all tested cell lines. QD conjugated OSI-420 demonstrated an IC60 of 2.5 µM in erlotinib-resistant A549 cell lines, where erlotinib or OSI-420 alone could not exhibit 60% inhibition when evaluated up to 20 µM. Similar cytotoxic enhancement of erlotinib was seen with QD-OSI 420 in other NSCLC cell lines as well. These results were strengthened by 3D-SCC model of A549 which revealed that QD-OSI 420 was significantly better in reducing in-vitro 3D tumor volume, as compared to pure drugs. This study, being one of its kind, explores the feasibility of conjugating OSI-420 with QDs as an alternative to traditional anti-cancer therapy, by improving intracellular drug delivery.