Activity In Cancer Cell Lines Research Articles

Enantioselective Synthesis of Clavaminol A, Xestoaminol C and their Stereoisomers Exhibiting Cytotoxic Activity

The simple preparation of the natural sphingoid bases possessing cytotoxic activity – the marine drugs Clavaminol A and Xestoaminol C and all their unnatural stereoisomers – in high enantiomeric purity (ca. 95 % of major enantiomer) was described. The individual enantiomers were obtained by the utilization of asymmetric Henry reaction. The diastereomers of target compounds were separated by column chromatography after transformation into corresponding 2‐phenyloxazoline derivatives. The individual stereoisomers of Clavaminol A and Xestoaminol C were evaluated for antiproliferative activity in cancer cell lines (A‐549; Jurkat; SH‐SY5Y, MG‐63). From the obtained IC50 values is obvious, that the stereoisomers of Xestoaminol C are more potent inhibitors of cell proliferation than the stereoisomers of Clavaminol A. Further, it was found, that stereoisomers with syn‐configuration exhibited larger antiproliferative effects in comparison with the stereoisomers having anti‐configuration, in both sphingoid bases. Nevertheless, the values of IC50 found for individual enantiomers in each of the enantiomeric pairs are rather comparable implying a possibility of using racemic mixtures for induction of cytotoxicity.

Investigating the antiangiogenic potential of Rumex vesicarius (humeidh), anticancer activity in cancer cell lines and assessment of developmental toxicity in zebrafish embryos.

Recent trends in anticancer therapy is to use therapeutic agents which not only kill the cancer cell, but are less toxic to surrounding normal cells/tissue. One approach is to cut the nutrient supply to growing tumor cells, by blocking the formation of new blood vessels around the tumor. As the phytochemicals and botanical crude extracts have proven their efficacy as natural antiangiogenic agents with minimum toxicities, there is need to explore varieties of medicinal plants for novel antiangiogenic compounds.Rumex vesicarius L. (Humeidh), is an annual herbal plant with proven medicinal values. The antiangiogenic potential, and developmental toxicity of humeidh in experimental animal models has never been studied before. The crude extracts were prepared from the roots, stems, leaves and flowers of Rumex vesicarius L. in methanol, chloroform, ethyl acetate and n-hexane. The developmental toxicity screening in zebrafish embryos, has revealed that Rumex vesicarius was not toxic to zebrafish embryos. The chloroform stem extract showed significant level of antiangiogenic activity in zebrafish angiogenic assay on a dose dependent manner. Thirty five (35) bioactive compounds were identified by gas chromatography mass spectrophotometry (GC–MS) analysis in the stem extract of Rumex vesicarius. Propanoic acid, 2-[(trimethylsilyl)oxy]-, trimethylsilyl ester, Butane, 1,2,3-tris(trimethylsiloxy), and Butanedioic acid, bis(trimethylsilyl) ester were identified as major compound present in the stem of R. vasicarius.The anticancer activity of roots, stem, leaves and flowers crude extract was evaluated in human breast cancer (MCF7), human colon carcinoma (Lovo, and Caco-2), human hepatocellular carcinoma (HepG2) cell lines. Most of the crude extracts did not show significant level of cytotoxicity in tested cancer cells line, except, chloroform extract of stem which exhibited strong anticancer activity in all tested cancer cells with IC50 values in micro molar range.Based on these results, it is recommended that formulation prepared from R. vesicarius can further be tested in clinical trials in order to explore its therapeutic potential as an effective and safe natural anticancer product.

TR1801-ADC: a highly potent cMet antibody-drug conjugate with high activity in patient-derived xenograft models of solid tumors.

cMet is a well‐characterized oncogene that is the target of many drugs including small molecule and biologic pathway inhibitors, and, more recently, antibody–drug conjugates (ADCs). However, the clinical benefit from cMet‐targeted therapy has been limited. We developed a novel cMet‐targeted ‘third‐generation’ ADC, TR1801‐ADC, that was optimized at different levels including specificity, stability, toxin–linker, conjugation site, and in vivo efficacy. Our nonagonistic cMet antibody was site‐specifically conjugated to the pyrrolobenzodiazepine (PBD) toxin–linker tesirine and has picomolar activity in cancer cell lines derived from different solid tumors including lung, colorectal, and gastric cancers. The potency of our cMet ADC is independent of MET gene copy number, and its antitumor activity was high not only in high cMet‐expressing cell lines but also in medium‐to‐low cMet cell lines (40 000–90 000 cMet/cell) in which a cMet ADC with tubulin inhibitor payload was considerably less potent. In vivo xenografts with low–medium cMet expression were also very responsive to TR1801‐ADC at a single dose, while a cMet ADC using a tubulin inhibitor showed a substantially reduced efficacy. Furthermore, TR1801‐ADC had excellent efficacy with significant antitumor activity in 90% of tested patient‐derived xenograft models of gastric, colorectal, and head and neck cancers: 7 of 10 gastric models, 4 of 10 colorectal cancer models, and 3 of 10 head and neck cancer models showed complete tumor regression after a single‐dose administration. Altogether, TR1801‐ADC is a new generation cMet ADC with best‐in‐class preclinical efficacy and good tolerability in rats.

Abstract 2172: Quantification of ERK activity in cancer cell lysates and tumor extract using differential sensing methods

Abstract The activity of protein kinases in biological samples is typically estimated by determining the phosphorylation status of either the kinase itself, or a known cellular substrate. This is typically evaluated by multi-step western blotting, or proteomics procedures. Such procedures typically provide qualitative estimates of the modifications in question. While immunoblotting and proteomics procedures can be used in a quantitative manner, their complicated workflow diminishes reproducibility. Futhermore, modifications do not necessarily correlate closely with a protein kinase’s activity. The motivation for this work was to assess the potential of a peptide array to quantify ERK activity in cancer cell lines and tumor samples, without the need to suppress related kinase activities. This work shows that a library of cross-reactive peptide-based biosensors, along with chemometric analysis can be used to profile a kinase activity in cancer cell lines. Significantly, the array is suitable for quantifying unknown levels of ERK activity in unfractionated cancer cell lysates and tumor samples using a multivariate regression model. The predicted values provided by our model were found to be comparable to those obtained by immune complex kinase assays. Note: This abstract was not presented at the meeting. Citation Format: Diana Zamora-Olivares, Tamer S. Kaoud, Lingyu Zeng, Mitchell Telles, Eric V. Anslyn, Kevin N. Dalby. Quantification of ERK activity in cancer cell lysates and tumor extract using differential sensing methods [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2172.

Preclinical Efficacy of Covalent-Allosteric AKT Inhibitor Borussertib in Combination with Trametinib in KRAS-Mutant Pancreatic and Colorectal Cancer.

Aberrations within the PI3K/AKT signaling axis are frequently observed in numerous cancer types, highlighting the relevance of these pathways in cancer physiology and pathology. However, therapeutic interventions employing AKT inhibitors often suffer from limitations associated with target selectivity, efficacy, or dose-limiting effects. Here we present the first crystal structure of autoinhibited AKT1 in complex with the covalent-allosteric inhibitor borussertib, providing critical insights into the structural basis of AKT1 inhibition by this unique class of compounds. Comprehensive biological and preclinical evaluation of borussertib in cancer-related model systems demonstrated a strong antiproliferative activity in cancer cell lines harboring genetic alterations within the PTEN, PI3K, and RAS signaling pathways. Furthermore, borussertib displayed antitumor activity in combination with the MEK inhibitor trametinib in patient-derived xenograft models of mutant KRAS pancreatic and colon cancer. SIGNIFICANCE: Borussertib, a first-in-class covalent-allosteric AKT inhibitor, displays antitumor activity in combination with the MEK inhibitor trametinib in patient-derived xenograft models and provides a starting point for further pharmacokinetic/dynamic optimization.

SHR-A1403, a novel c-Met antibody-drug conjugate, exerts encouraging anti-tumor activity in c-Met-overexpressing models.

Emerging evidence demonstrates that a c-Met antibody-drug conjugate (ADC) has superior efficacy and safety profiles compared with those of currently available small molecules or antibody inhibitors for the treatment of c-Met-overexpressing cancers. Here we described both the in vitro and in vivo efficacies of SHR-A1403, a novel c-Met ADC composed of a humanized IgG2 monoclonal antibody against c-Met conjugated to a novel cytotoxic microtubule inhibitor. SHR-A1403 showed high affinity to c-Met proteins derived from human or monkey and potent inhibitory effects in cancer cell lines with high c-Met protein expression. In mice bearing tumors derived from cancer cell lines or patient HCC tissues with confirmed c-Met overexpression, SHR-A1403 showed excellent anti-tumor efficacy. Antibody binding with c-Met contributed toSHR-A1403 endocytosis; the subsequent translocation to lysosomes and cytotoxicity of the released toxin are speculated to be predominant mechanisms underlying the anti-tumor activity of SHR-A1403. In conclusion, SHR-A1403 showed significant anti-tumor activity in cancer cell lines, xenograft mouse models and an HCC PDX model, which all have high c-Met levels. These data provide references for SHR-A1403 as a potential therapy for the treatment of cancers with c-Met overexpression.

Heterologous and cross-species tropism of cancer-derived extracellular vesicles.

Extracellular vesicles (EVs) are naturally occurring cargo delivery vesicles that have recently received considerable attention for their roles in intercellular communication in many physiological and pathological processes, including tumourigenesis. EVs generated by different tissues demonstrated specific homing: in particular, cancer-derived EVs showed a selective tropism for the tumor tissue from which the vesicles originated. For this property, EVs have been proposed as drug delivery tools for anti-cancer therapies, although the limited knowledge about their in vivo tropism hinders their therapeutic applications. The current study aimed to characterize the targeting properties of cancer-derived EVs in vitro and their biodistribution in vivo, by using an imaging approach.Methods: EVs were generated from: i) murine lung (LL/2) and colon (MC-38) cancer lines, ii) human lung cancer cell line (A549) and iii) human liver biopsy samples from healthy individuals. EVs were loaded with fluorescent dyes alone or in combination with a biopharmaceutical agent, the oncolytic adenovirus (OV), characterized for charge and size and tested for their activity in cancer cell lines. Finally, optical imaging was extensively applied to study in vivo and ex vivo the biodistribution of EVs originated from different sources in different mouse models of cancer, including xenograft, syngeneic graft and the MMTV-NeuT genetically modified animal.Results: We initially demonstrated that even loading EVs even with a large biopharmaceutical oncolytic viruses (OVs) did not significantly change their charge and dimension properties, while increasing their anti-neoplastic activity compared to the virus or EVs alone. Interestingly, this activity was observed even if the EVs derived from lung cancer were applied to colon carcinoma cell lines and vice versa, suggesting that the EV uptake occurred in vitro without any specificity for the cancer cells from which the vesicles originated. When administered i.v (intravenously) to the mouse models of cancer, the tumour-derived EVs, but not the EVs derived from a healthy tissue, demonstrated a selective accumulation of the fluorescence at the tumour site 24 h after injection; adding OVs to the formulation did not change the tumour-specific tropism of the EVs also in vivo. Most interestingly, the in vivo experiments confirmed the in vitro observation of the generalized tropism of tumour-derived EVs for any neoplastic tissue, independent of the tumour type or even the species originating the vesicles.Conclusions: Taken together, our in vitro and in vivo data demonstrate for the first time a heterologous, cross-species tumour-tropism for cancer-derived EVs. This finding challenges our current view on the homing properties of EVs and opens new avenues for the selective delivery of diagnostic/therapeutic agents to solid tumours.

Exosomes as nanocarriers for the delivery of bioactive compounds from black bean extract with antiproliferative activity in cancer cell lines

Abstract Exosomes are membrane-derived nanovesicles secreted by a variety of cell types to the extracellular space for intercellular communication. Based on this biological function, exosomes have been used in numerous applications such as drug delivery. In this work, exosomes isolated from MCF7, Caco2, PC3 and HepG2 cell lines were characterized and loaded with bioactive compounds from black bean extract by electroporation. The cellular uptake and the antiproliferative activity of exosomal formulation were evaluated in cancerous cells in vitro, resulting in a maximum exosome uptake after 24 h with an enhanced antiproliferative activity. Our results suggest that exosomes are a promising alternative for the development of novel and more efficient cancer therapies.

Cytotoxic profile activities of ethanolic and methanolic extracts of chicory plant (Cichorium intybus L.)

This study aims to highlight the antioxidant and cytotoxic effects of Cichorium intybus L.. The cytotoxic activity for cancer cell lines was evaluated by MTT assay. Total phenol and flavonoid conte...

Identification of Novel Pyruvate Dehydrogenase Kinase 1 (PDK1) Inhibitors by Kinase Activity-Based High-Throughput Screening for Anticancer Therapeutics.

Warburg effect, a preference of aerobic glycolysis for energy production even in the presence of adequate oxygen, is one of the most prominent distinctions of cancer cells from their normal equivalents. Upregulated pyruvate dehydrogenase kinase 1 (PDK1) was found to dominate the pivotal switch from mitochondrial respiration to aerobic glycolysis by inactivating pyruvate dehydrogenase (PDH) in cancer cells. PDK1 inhibition may lead to an unfavorable environment for cancer cells, which presents an opportunity for anticancer therapy. However, up to now, only limited number of PDK1 inhibitors were reported. In this work, we reported our attempt to discover novel small molecules from a diverse chemical library containing 15 000 small molecules selected from the Chembridge screening library. We developed a kinase activity-based high throughput screening (HTS) assay for initial screening of PDK1 inhibitors. Seven PDK1 inhibitory compounds were identified with IC50 values range from 0.68 and 45.69 μM. Follow up evaluations on these compounds revealed good PDK1 binding affinity and antiproliferative activities in cancer cell lines, with two novel hits (9 and 10) clearly outperformed others compounds in terms of PDK1 inhibition and the suppression of cancer cell proliferation. 9 and 10 may serve as new chemistry starting points for further structural modifications to improve the potency on PDK1 inhibition for anticancer treatment.

Inferences of individual drug responses across diverse cancer types using a novel competing endogenous RNA network

Differences in individual drug responses are an obstacle to progression in cancer treatment, and predicting responses would help to plan treatment. The accumulation of cancer molecular profiling and drug response data provides opportunities and challenges to identify novel molecular signatures and mechanisms of tumor responsiveness to drugs. This study evaluated drug responses with a competing endogenous RNA (ceRNA) system that depended on competition between diverse RNA species. We identified drug response‐related ceRNA (DRCEs) by combining the sequence and expression data of long noncoding RNA (lncRNA), microRNA (miRNA), and messenger RNA (mRNA), and the survival data of cancer patients treated with drugs. We constructed a patient–drug two‐layer integrated network and used a linear weighting method to predict individual drug responses. DRCEs were found to be significantly enriched in known cancer and drug‐associated data resources, involved in biological processes known to mediate drug responses, and correlated to drug activity in cancer cell lines. The dysregulation of DRCE expression influenced drug response‐associated functions and pathways, suggesting DRCEs as potential therapeutic targets affecting drug responses. A further case study in breast invasive carcinoma (BRCA) found that DRCE expression was consistent with the drug response pattern and the aberrant expression of the two NEAT1‐related DRCEs may lead to poor response to tamoxifen therapy for patients with TP53 mutations. In summary, this study provides a framework for ceRNA‐based evaluation of clinical drug responses across multiple cancer types. Understanding the underlying molecular mechanisms of drug responses will allow improved response to chemotherapy and outcomes of cancer treatment.

Abstract 685: Structural study of the 3'-end G-quadruplex formed in the human PDGFR-β promoter: Insight into a transcriptional inhibitor element

Abstract Aberrant expression of PDGFR-β promotes multiple hallmarks of cancer, and its transcriptional regulation provides an attractive means to inhibit the PDGFR-β signaling pathway. The human PDGFR-β promoter nuclease hypersensitive element (NHE) can form multiple G-quadruplexes. While the most stable G-quadruplex formed in the human PDGFR-β promoter NHE region is the 5'-mid G-quadruplex, the 3'-end sequence that contains a 3'-GGA run forms a less stable G-quadruplex. Interestingly, the G-quadruplex formed in the 3'-end region of the NHE is recently found to be a transcriptional repressor of PDGFR-β, and a small molecule ellipticine, GSA1129, is shown to selectively stabilize the 3'-end G-quadruplex and repress PDGFR-β activity in cancer cell lines and in a preclinical animal model. Therefore, understanding the molecular structure of the 3'-end G-quadruplex is important for small molecule targeting in PDGFR-β gene regulation. Using Nuclear Magnetic Resonance (NMR) spectroscopy, we found that the 3'-end G-quadruplex formed in the extended PDGFR-β NHE 3'-end sequence consists of two novel intramolecular end-insertion G-quadruplexes, one with a 3'-non-adjacent flanking guanine inserted into the 3'-external tetrad (3'-insertion-G4), and another with a 5'-non-adjacent flanking guanine inserted into the 5'-external tetrad (5'-insertion-G4), respectively. The two guanines in the GGA-run move up or down within the G-quadruplex to accommodate the inserted guanine. The two end-insertion G-quadruplexes co-exist in equilibrium under physiological salt conditions. In the 3'-insertion-G4, the 3' non-adjacent guanine G20 is involved in the formation of the 3'-external G-tetrad, with the two guanines from the GGA-run involved in the formation of the 5'-external and middle G-tetrads, thereby inducing the formation of a bulge loop structure from the 3'-flanking strand. In the 5'-insertion-G4, the 5'-non-adjacent flanking guanine G0 is involved in the formation of the 5'-external G-tetrad, with the two guanines from the GGA-run involved in the formation of the middle and 3'-external G-tetrads, thereby inducing the formation of a lateral loop from the 5'-flanking residues on top of the 5'-external tetrad. The loop interactions and capping structures of the two end-insertion G-quadruplexes appear to be different. For the 3'-insertion-G4, only the 5'-flanking bases stabilize the structure. For the 5'-insertion-G4, the flanking residues at both the 5'- and 3'-ends stabilize the structure, and a favorable capping structure appears to be adopted by the 5'-lateral loop. Significantly, the formation of two equilibrating end-insertion G-quadruplexes appears to depend on the GGA-run and the guanine-containing flanking sequences. The unique end-insertion structures and capping conformations may provide a specific platform for small molecule targeting. Citation Format: Buket Onel, Clement Lin, Danzhou Yang. Structural study of the 3'-end G-quadruplex formed in the human PDGFR-β promoter: Insight into a transcriptional inhibitor element [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 685.

Estradiol dimer inhibits tubulin polymerization and microtubule dynamics

Microtubule dynamics is one of the major targets for new chemotherapeutic agents. This communication presents the synthesis and biological profiling of steroidal dimers based on estradiol, testosterone and pregnenolone bridged by 2,6-bis(azidomethyl)pyridine between D rings. The biological profiling revealed unique properties of the estradiol dimer including cytotoxic activities on a panel of 11 human cell lines, ability to arrest in the G2/M phase of the cell cycle accompanied with the attenuation of DNA/RNA synthesis. Thorough investigation precluded a genomic mechanism of action and revealed that the estradiol dimer acts at the cytoskeletal level by inhibiting tubulin polymerization. Further studies showed that estradiol dimer, but none of the other structurally related dimeric steroids, inhibited assembly of purified tubulin (IC50, 3.6 μM). The estradiol dimer was more potent than 2-methoxyestradiol, an endogenous metabolite of 17β-estradiol and well-studied microtubule polymerization inhibitor with antitumor effects that was evaluated in clinical trials. Further, it was equipotent to nocodazole (IC50, 1.5 μM), an antimitotic small molecule of natural origin. Both estradiol dimer and nocodazole completely and reversibly depolymerized microtubules in interphase U2OS cells at 2.5 μM concentration. At lower concentrations (50 nM), estradiol dimer decreased the microtubule dynamics and growth life-time and produced comparable effect to nocodazole on the microtubule dynamicity. In silico modeling predicted that estradiol dimer binds to the colchicine-binding site in the tubulin dimer. Finally, dimerization of the steroids abolished their ability to induce transactivation by estrogen receptor α and androgen receptors. Although other steroids were reported to interact with microtubules, the estradiol dimer represents a new structural type of steroid inhibitor of tubulin polymerization and microtubule dynamics, bearing antimitotic and cytotoxic activity in cancer cell lines.

Bitter gourd (Momordica charantia) as a rich source of bioactive components to combat cancer naturally: Are we on the right track to fully unlock its potential as inhibitor of deregulated signaling pathways

Research over decades has progressively explored pharmacological actions of bitter gourd (Momordica charantia). Biologically and pharmacologically active molecules isolated from M. charantia have shown significant anti-cancer activity in cancer cell lines and xenografted mice. In this review spotlight was set on the bioactive compounds isolated from M. charantia that effectively inhibited cancer development and progression via regulation of protein network in cancer cells. We summarize most recent high-quality research work in cancer cell lines and xenografted mice related to tumor suppressive role-play of M. charantia and its bioactive compounds. Although M. charantia mediated health promoting, anti-diabetic, hepatoprotective, anti-inflammatory effects have been extensively investigated, there is insufficient information related to regulation of signaling networks by bioactive molecules obtained from M. charantia in different cancers. M. charantia has been shown to modulate AKT/mTOR/p70S6K signaling, p38MAPK-MAPKAPK-2/HSP-27 pathway, cell cycle regulatory proteins and apoptosis-associated proteins in different cancers. However, still there are visible knowledge gaps related to the drug targets in different cancers because we have not yet developed comprehensive understanding of the M. charantia mediated regulation of signal transduction pathways. To explore these questions, experimental platforms are needed that can prove to be helpful in getting a step closer to personalized medicine.

VDAC1 Mediated Anticancer Activity of Gallic Acid in Human Lung Adenocarcinoma A549 Cells.

Gallic acid (GA) is generally distributed in a variety of plants and foods, and possesses cell growth-inhibiting activities in cancer cell lines. In the present study, the impact of GA on cell viability, apoptosis induction and possible molecular mechanisms in cultured A549 lung carcinoma cells was investigated. In vitro experiments showed that treating A549 cells with various concentrations of GA inhibited cell viability and induced apoptosis in a dose-dependent manner. In order to understand the mechanism by which GA inhibits cell viability, comparative proteomic analysis was applied. The changed proteins were identified by Western blot and siRNA methods. Two-dimensional electrophoresis revealed changes that occurred to the cells when treated with or without GA. Four up-regulated protein spots were clearly identified as malate dehydrogenase (MDH), voltagedependent, anion-selective channel protein 1(VDAC1), calreticulin (CRT) and brain acid soluble protein 1(BASP1). VDAC1 in A549 cells was reconfirmed by western blot. Transfection with VDAC1 siRNA significantly increased cell viability after the treatment of GA. Further investigation showed that GA down regulated PI3K/Akt signaling pathways. These data strongly suggest that up-regulation of VDAC1 by GA may play an important role in GA-induced, inhibitory effects on A549 cell viability.

Inhibitors Targeting IGF‐1r and mTOR Induce Synergistic Cell Growth Inhibition and Enhance Apoptotic Activity in Cancer Cell Lines

Insulin‐like growth factor I (IGF‐1) and its cognate receptor (IGF‐1r) show prominent molecular irregularities in many tumor types. Autocrine function for the growth factor is documented in multiple cancers and cell lines. In experimental settings the cell lines show a spectrum of dependency on IGF‐1. Presence of IGF‐1 inhibits programmed cell death with its activation of Akt through the PI3‐Akt‐mTOR signaling pathway. The inhibition extends to chemotherapy‐induced cell death as reported in instances where mammalian target of Rapamycin (mTOR) inhibitors are used pharmacologically for induction of apoptosis. We investigated the effects of concurrent targeting of IGF‐1r and mTOR with potent small molecule inhibitors in cancer cell lines that are dependent on IGF‐1 for cell growth. We show that the drug combination synergistically inhibited cell growth and induced apoptosis at inhibitor concentrations that are minimally toxic to normal lung fibroblast cells but potently inhibits PI3‐Akt activation.Support or Funding InformationUSDA/NIFA # SCX‐311‐17‐14 (1890 research program @SCSU)NIGMS/NIH IDeA SC INBRE P20 RR‐016461This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

72P - Up-regulation of miR-1266-5p suppressed hTERT expression and telomerase activity in cancer cell lines

72P - Up-regulation of miR-1266-5p suppressed hTERT expression and telomerase activity in cancer cell lines

Identification and characterization of SSE15206, a microtubule depolymerizing agent that overcomes multidrug resistance

Microtubules are highly dynamic structures that form spindle fibres during mitosis and are one of the most validated cancer targets. The success of drugs targeting microtubules, however, is often limited by the development of multidrug resistance. Here we describe the discovery and characterization of SSE15206, a pyrazolinethioamide derivative [3-phenyl-5-(3,4,5-trimethoxyphenyl)-4,5-dihydro-1H-pyrazole-1-carbothioamide] that has potent antiproliferative activities in cancer cell lines of different origins and overcomes resistance to microtubule-targeting agents. Treatment of cells with SSE15206 causes aberrant mitosis resulting in G2/M arrest due to incomplete spindle formation, a phenotype often associated with drugs that interfere with microtubule dynamics. SSE15206 inhibits microtubule polymerization both in biochemical and cellular assays by binding to colchicine site in tubulin as shown by docking and competition studies. Prolonged treatment of cells with the compound results in apoptotic cell death [increased Poly (ADP-ribose) polymerase cleavage and Annexin V/PI staining] accompanied by p53 induction. More importantly, we demonstrate that SSE15206 is able to overcome resistance to chemotherapeutic drugs in different cancer cell lines including multidrug-resistant KB-V1 and A2780-Pac-Res cell lines overexpressing MDR-1, making it a promising hit for the lead optimization studies to target multidrug resistance.

Oncogene Expression Modulation in Cancer Cell Lines by DNA G-Quadruplex-Interactive Small Molecules.

Nucleic acids are prone to structural polymorphism and a number of structures may be formed in addition to the well-known DNA double helix. Among these is a family of nucleic acid four-stranded structures known as G-quadruplexes (G4). These quadruplex structures can be formed by sequences containing repetitive guanine-rich tracks and the analysis of Non-B-DNA database indicated an enrichment of these sequences in genomic regions controlling cellular proliferation, such as for example in the promoter regions of c- MYC, k-RAS, c-KIT, HSP90 and VEGF among others. The broad concept of G4 targeting with small molecules is now generally accepted as a promising novel approach to anticancer therapy and several small molecules with antiproliferative activity in cancer cell lines have also been shown to stabilize these DNA structures, thus suggesting a potential application of G4-interactive small molecules as new anticancer drugs. Herein we review, by targeted oncogene and main chemical scaffold, those G4-interactive small molecules with reported gene expression modulatory activity in cancer cell lines. The data obtained so far are encouraging but further efforts are needed to validate G4 as drug targets and optimize the structure of G4- interactive small molecules into new anticancer drugs.

Comparative solution equilibrium and structural studies of half-sandwich ruthenium(II)(η6-toluene) complexes of picolinate derivatives

Five Ru(II)(η6-toluene) complexes formed with 2-picolinic acid and its various derivatives have been synthesized and characterized. X-ray structures of four complexes are also reported. Complex formation processes of [Ru(II)(η6-toluene)(H2O)3]2+ organometallic cation with the metal-free ligands were studied in aqueous solution in the presence of chloride ions by the combined use of 1H NMR spectroscopy, UV–visible spectrophotometry and pH-potentiometry. Solution stability, chloride ion affinity and lipophilicity of the complexes were characterized together with in vitro cytotoxic and antiproliferative activity in cancer cell lines being sensitive and resistant to classic chemotherapy and in normal cells as well. Formation of mono complexes such as [Ru(η6-toluene)(L)(Z)]+/0 (L: completely deprotonated ligand; Z = H2O/Cl−) with high stability and [Ru(η6-toluene)(L)(OH)] was found in solution. The pKa values (8.3–8.7) reflect the formation of low amount of mixed hydroxido species at pH 7.4 at 0.2 M KCl ionic strength. The complexes are fairly hydrophilic and show moderate chloride ion affinity and fast chloride-water exchange processes. The studied complexes exhibit no cytotoxic activity in human cancer cells (IC50 > 100 μM), only complexes formed with 2-picolinic acid (1) and its 3-methyl derivative (2) represented a moderate antiproliferative effect (IC50 = 84.8 (1), 79.2 μM (2)) on a multidrug resistant colon adenocarcinoma cell line revealing considerable multidrug resistant selectivity. Complexes 1 and 2 bind to human serum albumin covalently and relatively slowly with moderate strength at multiple binding sites without ligand cleavage.