Ng, Po Yan. / Thesis submitted in: November 2006. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 109-120). / Abstracts in English and Chinese. / Acknowledgement --- p.i / Abstract --- p.ii / 摘要 --- p.iii / Table of Contents --- p.iv / List of Figures --- p.viii / List of Tables --- p.xi / List of Abbreviation --- p.xii / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- A General Introduction to the Development and Clinical Activities of Platinum Drugs --- p.1 / Chapter 1.1.1 --- Platinum Drugs used in a Clinical Setting --- p.4 / Chapter 1.1.2 --- Platinum Drugs under Clinical Trials --- p.5 / Chapter 1.1.3 --- Platinum Compounds with Dual Mechanisms --- p.7 / Chapter 1.2 --- Platinum Drug Antitumor Mechanism --- p.9 / Chapter 1.3 --- Limitations of Platinum Drugs --- p.12 / Chapter 1.3.1 --- Toxicity --- p.12 / Chapter 1.3.2 --- Drug Resistance or Cross Resistance --- p.15 / Chapter 1.3.2.1 --- Reduced Drug Accumulation or Increased Drug Efflux --- p.16 / Chapter 1.3.2.2 --- Drug Inactivation --- p.18 / Chapter 1.3.2.3 --- Enhanced DNA Repair --- p.19 / Chapter 1.4 --- Why Combinational Therapy? --- p.21 / Chapter 1.4.1 --- Antimetabolites --- p.20 / Chapter 1.4.2 --- Topoisomerase Inhibitors --- p.22 / Chapter 1.4.3 --- Tubulin-Active Antimitotic Agents --- p.24 / Chapter 1.4.4 --- Demethylcantharidin as a potential candidate for drug combination --- p.28 / Chapter 1.5 --- Study Objectives --- p.31 / Chapter Chapter 2 --- Materials and Methods / Chapter 2.1 --- Cell Lines --- p.33 / Chapter 2.2 --- Cancer Cell Preparation / Chapter 2.2.1 --- Chemicals and Reagents --- p.33 / Chapter 2.2.2 --- Cell Culture Practice --- p.34 / Chapter 2.2.2.1 --- Subcultures --- p.35 / Chapter 2.2.2.2 --- Cryopreservation --- p.37 / Chapter 2.2.2.3 --- Thawing Cryopreservated Cells --- p.38 / Chapter 2.2.3 --- Development of Drug-Resistant Cell Lines --- p.39 / Chapter 2.3 --- Growth Inhibition Assay / Chapter 2.3.1 --- Evaluation of Cytotoxicity in vitro --- p.40 / Chapter 2.3.2 --- Drug Pretreatment --- p.43 / Chapter 2.3.3 --- Drug Pre-sensitization with Concurrent Treatment --- p.44 / Chapter 2.4 --- Calculations for Drug Combinations --- p.46 / Chapter 2.5 --- Statistical Analysis --- p.49 / Chapter Chapter 3 --- Results and Discussions / Chapter 3.1 --- In vitro Cytotoxicity and Evaluation of Drug Resistance --- p.50 / Chapter 3.2 --- Role of Leaving Ligand in a Platinum Complex --- p.58 / Chapter 3.3 --- Priority in Selecting the Most Effective Drug Combination --- p.66 / Chapter 3.4 --- Drug Combination Studies / Chapter 3.4.1 --- Drug Combination Prescreening --- p.68 / Chapter 3.4.1.1 --- Comparison of the effectiveness of the three Drug Combinations --- p.72 / Chapter 3.4.1.2 --- Rationale for Drug Combination Studies presented in Section 3.4.2 & 3.4.3 --- p.73 / Chapter 3.4.2 --- Drug Pre-sensitization Studies in Colorectal Cancer Cell Lines --- p.74 / Chapter 3.4.2.1 --- Comparison of Drug Pre-sensitization Treatment in Sensitive Colorectal Cancer Cell Lines --- p.84 / Chapter 3.4.2.2 --- Comparison of Drug Pre-sensitization Treatment in Sensitive and Oxaliplatin Resistant HCT116 Colorectal Cancer Cell Lines --- p.87 / Chapter 3.4.3 --- Drug Pre-sensitization Studies in Liver Cancer Cell Lines --- p.89 / Chapter 3.4.3.1 --- Comparison of Drug Pre-sensitization Treatment in Sensitive Liver Cancer Cell Lines --- p.99 / Chapter 3.4.3.2 --- Comparison of Drug Pre-sensitization Treatment in Sensitive and Cisplatin Resistant SK-Hepl Liver Cancer Cell Line --- p.101 / Chapter 3.5 --- Possible Explanation to the Observed Drug Combination Effect --- p.103 / Chapter 3.6 --- General Protocols for Drug Combinations --- p.105 / Chapter Chapter 4 --- Conclusions / Reference --- p.109 / Appendices --- p.121 / Chapter I a. --- "Raw Data of Pre-screening for HCT116 (Cisplatin, [Pt(DMC)(NH3)2] and Pt(DMC)(NH2CH3)2])" --- p.122 / Chapter I b. --- "Raw Data of Pre-screening for HCT116 ([Pt(DMC)(R,R-DACH)] and Oxaliplatin)" --- p.123 / Chapter II a. --- "Raw Data of Pre-screening for SK-Hepl (Cisplatin, [Pt(DMC)(NH3)2] and Pt(DMC)(NH2CH3)2])" --- p.124 / Chapter II b. --- "Raw Data of Pre-screening for SK-Hepl ([Pt(DMC)(R,R-DACH)] and Oxaliplatin)" --- p.125 / Chapter III a. i) --- "Isobolograms for HCT116 (Cisplatin, [Pt(DMC)(NH3)2] and Pt(DMC)(NH2CH3)2])" --- p.126 / Chapter III a. ii) --- "Raw Data for HCT116 (Cisplatin, [Pt(DMC)(NH3)2] and Pt(DMC)(NH2CH3)2])" --- p.127 / Chapter III b. i) --- "Isobolograms for HCT116 ([Pt(DMC)(R,R-DACH)] and Oxaliplatin)" --- p.128 / Chapter III b. ii) --- "Raw Data for HCT116 ([Pt(DMC)(R,R-DACH)] and Oxaliplatin)" --- p.129 / Chapter IV a. i) --- "Isobolograms for HCT1160xaR (Cisplatin, [Pt(DMC)(NH3)2] and Pt(DMC)(NH2CH3)2])" --- p.130 / Chapter IV a. ii) --- "Raw Data for HCT1160xaR (Cisplatin, [Pt(DMC)(NH3)2] and Pt(DMC)(NH2CH3)2])" --- p.131 / Chapter IV b. i) --- "Isobolograms for HCT1160xaR ([Pt(DMC)(R,R-DACH)] and Oxaliplatin)" --- p.132 / Chapter IV b. ii) --- "Raw Data for HCT1160xaR ([Pt(DMC)(R,R-DACH)] and Oxaliplatin)" --- p.133 / Chapter V a. i) --- "Isobolograms for HT29 (Cisplatin, [Pt(DMC)(NH3)2] and Pt(DMC)(NH2CH3)2])" --- p.134 / Chapter V a. ii) --- "Raw Data for HT29 (Cisplatin, [Pt(DMC)(NH3)2] and Pt(DMC)(NH2CH3)2])" --- p.135 / Chapter V b. i) --- "Isobolograms for HT29 ([Pt(DMC)(R,R-DACH)] and Oxaliplatin)" --- p.136 / Chapter V b. ii) --- "Raw Data for HT29 ([Pt(DMC)(R,R-DACH)] and Oxaliplatin)" --- p.137 / Chapter VI a. i) --- Isobolograms for Hep G2 (Cisplatin and [Pt(DMC)(NH3)2]) --- p.138 / Chapter VI a. ii) --- Raw Data for Hep G2 (Cisplatin and [Pt(DMC)(NH3)2]) --- p.139 / Chapter VI b. i) --- "Isobolograms for Hep G2 ([Pt(DMC)(R,R-DACH)] and Oxaliplatin)" --- p.140 / Chapter VI b. ii) --- "Raw Data for Hep G2 ([Pt(DMC)(R,R-DACH)] and Oxaliplatin)" --- p.141 / Chapter VII a. i) --- "isobolograms for SK Hep 1 (Cisplatin, [Pt(DMC)(NH3)2] and Pt(DMC)(NH2CH3)2])" --- p.142 / Chapter VII a. ii) --- "Raw Data for SK Hep 1 (Cisplatin, [Pt(DMC)(NH3)2] and Pt(DMC)(NH2CH3)2])" --- p.143 / Chapter VII b.i) --- "Isobolograms for SK Hep 1 ([Pt(DMC)(R,R-DACH)] and Oxaliplatin)" --- p.144 / Chapter VII b. ii) --- "Raw Data for SK Hep 1 ([Pt(DMC)(R,R-DACH)] and Oxaliplatin)" --- p.145 / Chapter VIII a. i) --- "Isobolograms for SK Hep ICisR (Cisplatin, [Pt(DMC)(NH3)2] and Pt(DMC)(NH2CH3)2])" --- p.146 / Chapter VIII a. ii) --- "Raw Data for SK Hep ICisR (Cisplatin, [Pt(DMC)(NH3)2] and Pt(DMC)(NH2CH3)2])" --- p.147 / Chapter VIII b. i) --- "Isobolograms for SK Hep ICisR ([Pt(DMC)(R,R-DACH)] and Oxaliplatin)" --- p.148 / Chapter VIII b. ii) --- "Raw Data for SK Hep ICisR ([Pt(DMC)(R,R-DACH)] and Oxaliplatin)" --- p.149

Text in English / Specially prepared 2-amino-5-bromo-3-iodoacetophenone and 5-bromo-2-hydroxy-3 iodoacetophenone were subjected to Claisen-Schmidt aldol condensation with benzaldehyde derivatives followed by sequential and/or one-pot palladium catalyzed Sonogashira cross coupling and heteroannulation of the 3-alkynylated intermediates to afford indole-chalcones and benzofuran-chalcones, respectively. The indole-chalcones derivatives were, in turn, subjected to trifluoroacetic anhydride in tetrahydrofuran under reflux to afford the corresponding 3-trifluoroacetyl substituted indole-chalcone derivatives. The coupling constant values (Jtrans) of about 16.0 Hz for the chalcone derivatives corresponding to the vinylic protons confirmed the trans geometry of the α,β-unsaturated carbonyl framework in all the cases. Their trans geometry of the chalcone derivatives was further confirmed by single crystal X-ray diffraction (XRD) analyses. Further structural elaboration of the ambident electrophilic α,β unsaturated carbonyl (chalcone) moiety of the indole-chalcones and the analogous benzofuran chalcones with 2-aminothiophenol afforded novel benzothiezapine-appended indole and benzofuran hybrids, respectively. Sonogashira cross-coupling of 5-bromo-2-hydroxy-3 iodoacetophenone with terminal acetylenes followed by heteroannulation of the intermediate 3-alkynylated 5-bromo-2-hydroxyacetophenones afforded the corresponding 7-acetyl-2-aryl-5-bromobenzofurans in a single-pot operation. The oximes derived from the 7-acetyl–substituted 2-aryl-5-bromobenzofurans were subjected to Beckmann rearrangement with triflic acid in acetonitrile under reflux. We isolated the corresponding 7-amino-2-aryl-5 bromobenzofuran derivatives formed from hydrolysis in situ of the intermediate 7-acetamide 2-aryl-5-bromobenzofurans. Amino-dechlorination of the 4-chloroquinazoline derivatives with the 7-aminobenzofurans afforded novel benzofuran 4-aminoquinazoline hybrids. The prepared compounds were characterized using a combination of nuclear magnetic resonance (1H-NMR & 13C-NMR including 19F-NMR), infrared (IR) and mass spectroscopic techniques complemented with single crystal X-ray diffraction (XRD) analyses and/or density functional (DFT) method. The benzofuran-chalcone 203a–y derivatives were evaluated for anti-growth effect against the breast cancer (MCF-7) cell line by the MTT cell viability assay. Their mode of cancer cell death (apoptosis versus necrosis) was detected by Annexin V-Cy3 SYTOX staining and caspase-3 activation. The most cytotoxic compounds 203i and 203o were also evaluated for potential to inhibit tubulin polymerization and/or epidermal growth factor receptor-tyrosine kinase (EGFR-TK) phosphorylation. The experimental results were complemented with theoretical data from molecular docking into ATP binding site of the EGFR and colchicine binding site of tubulin, respectively. The benzofuran–4-aminoquinazoline hybrids 215a–j, on the other hand, were evaluated for antiproliferative propeties in vitro against the human lung cancer (A549), epithelial colorectal adenocarcinoma (Caco-2) and hepatocellular carcinoma (C3A) cell lines. The benzofuran-aminoquinazoline hybrids were also evaluated for potential to induce apoptosis and for their capability to inhibit EGFR-TK phosphorylation complemented with molecular docking (in silico) into the ATP binding site of EGFR. Mechanistic studies demonstrated that the benzofuran-appended aminoquinazoline hybrids 215d and 215j induced apoptosis via activation of caspase-3 pathway. Moreover, compounds 215d and 215j exhibited significant and moderate inhibitory effects against EGFR (IC50 = 29.3 nM and 61.5 nM, respectively) when compared to Gefitinib (IC50 = 33.1 nM). Molecular docking of compounds 215 into EGFR-TK active site suggested that they bind to the region of EGFR like Gefitinib does. / Chemistry / D. Phil. (Chemistry)

Nous proposons un modèle d’automate pour le cycle cellulaire lié à l’horloge circadienne. Ce modèle est utilisé pour déterminer la toxicité de différents schémas d’administration d’agents anticancéreux selon un profil temporel déterminé, dans le but d’optimiser l’efficacité de la chronothérapie des cancers. Fondé sur les transitions séquentielles entre les phases successives du cycle cellulaire G1, S (réplication de l’ADN), G2 et M (mitose), le modèle permet de simuler la distribution des phases du cycle cellulaire et son entraînement par l’horloge circadienne. Le modèle est utilisé pour évaluer l’effet du profil d’administration circadienne de deux agents anticancéreux, le 5-fluorouracile (5-FU) et l’oxaliplatine (l-OHP). Ces médicaments diffèrent par leur mode d’action mais sont complémentaires dans le traitement du cancer colorectal. Le 5-FU, considéré en premier, exerce ses effets cytotoxiques sur les cellules en phase S. Divers profils d’administration circadienne sont comparés, qui diffèrent par le temps du maximum d’administration du 5-FU. Le modèle explique pourquoi un minimum de cytotoxicité est obtenu lorsque le temps du pic d’administration approche 4h du matin, ce qui correspond au profil temporel d’administration utilisé en pratique clinique pour le 5-FU. Nous montrons comment la cytotoxicité de l’agent anticancéreux est affectée par la variabilité de la durée des phases du cycle cellulaire et par la durée du cycle cellulaire en présence et en absence d’entraînement par l’horloge circadienne. Les résultats indiquent qu’un même profil temporel d’administration peut avoir une cytotoxicité minimale pour une population cellulaire (correspondant à une population de cellules saines), et une cytotoxicité élevée pour une seconde population (correspondant à des cellules tumorales). Ainsi le modèle permet de mettre en lumière les mécanismes susceptibles d’améliorer simultanément la chronotolérance et la chronoefficacité des agents anticancéreux. Le cas de l’oxaliplatine (l-OHP) est considéré dans un second temps. Contrairement au 5-FU, l’oxaliplatine élimine les cellules quelle que soit sa phase dans le cycle cellulaire. La phamacocinétique des thiols plasmatiques et du glutathion intracellulaire est incorporée au modèle. Ces composés interfèrent avec l’action de l’OHP en formant des complexes inactifs. Le modèle montre comment des variations circadiennes dans la cytotoxicité de l-OHP peuvent résulter de rythmes circadiens dans les niveaux de thiols plasmatiques et de glutathion. En accord avec les résultats expérimentaux et cliniques, les simulations numériques du modèle d’automate pour le cycle cellulaire montrent que les profiles temporels minimisant la cytotoxicité de l’oxaliplatine sont en antiphase avec ceux minimisant la cytotoxicité du 5-fluorouracile./We propose an automaton model for the cell cycle coupled to the circadian clock. We use this model to assess the toxicity of various circadian patterns of anticancer drug delivery so as to enhance the efficiency of cancer chronotherapy. Based on the sequential transitions between the successive phases G1, S (DNA replication), G2, and M (mitosis) of the cell cycle, the model allows us to simulate the distribution of cell cycle phases as well as its entrainment by the circadian clock. We use the model to evaluate circadian patterns of administration of two anticancer drugs, 5-fluorouracil (5-FU) and oxaliplatin (l-OHP). These drugs, which differ by their mode of action, are complementary in the clinical treatment of colorectal cancer. We first consider the case of 5-FU, which exerts its cytotoxic effects on cells in S phase. We compare various circadian patterns of drug administration differing by the time of maximum drug delivery. The model explains why minimum cytotoxicity is obtained when the time of peak delivery is close to 4 a.m. which corresponds to the temporal pattern of administration used clinically for 5-FU. We also determine how cytotoxicity is affected by the variability in duration of cell cycle phases and by cell cycle length, in the presence or absence of entrainment by the circadian clock. The results indicate that the same temporal pattern of drug administration can have minimum cytotoxicity toward one cell population, e.g. of normal cells, and at the same time can display high cytotoxicity toward a second cell population, e.g. of tumour cells. Thus, the model allows us to uncover factors that may contribute to improve simultaneously chronotolerance and chronoefficacy of anticancer drugs. We next consider the case of oxaliplatin (l-OHP), which, in contrast to 5-FU, kills cells in different phases of the cell cycle. We incorporate into the model the pharmacokinetics of plasma thiols and intracellular glutathione, which interfere with the action of the drug by forming with it inactive complexes. The model shows how circadian changes in l-OHP cytotoxicity may arise from circadian variations in the levels of plasma thiols and glutathione. Corroborating experimental and clinical results, the numerical simulations of the automaton model for the cell cycle account for the observation that the temporal profiles minimizing l-OHP cytotoxicity are in antiphase with those minimizing cytotoxicity for 5-FU.<p> / Doctorat en Sciences agronomiques et ingénierie biologique / info:eu-repo/semantics/nonPublished

Indiana University-Purdue University Indianapolis (IUPUI) / Signal transducer and activator of transcription 3 (STAT3) is constitutively activated in malignant tumors, and its activation is associated with high histological grade and advanced cancer stage. STAT3 has been shown to play important roles in multiple aspects of cancer aggressiveness including proliferation, survival, self-renewal, migration, invasion, angiogenesis and immune response by regulating the expression of diverse downstream target genes. Thus, inhibiting STAT3 promises to be an attractive strategy for treatment of advanced tumors with metastatic potential. We firstly identified a STAT3 inhibitor, inS3-54, by targeting the DNA-binding site of STAT3 using an in-silico screening approach; however, inS3-54 was finally found not to be appropriate for further studies because of low specificity on STAT3 and poor absorption in mice. To develop an effective and specific STAT3 inhibitor, we identified 89 analogues for the structure-activity relationship analysis. By using hematopoietic progenitor cells isolated from wild-type and STAT3 conditional knockout mice, further studies showed that three analogues (A18, A26 and A69) only inhibited STAT3-dependent colony formation of hematopoietic progenitor cells, indicating a higher selectivity for STAT3 than their parental compound, inS3-54. These compounds were found to (1) inhibit STAT3-specific DNA binding activity; (2) bind to STAT3 protein; (3) suppress proliferation of cancer cells harboring aberrant STAT3 signaling; (4) inhibit migration and invasion of cancer cells and (5) inhibit STAT3-dependent expression of downstream targets by blocking the binding of STAT3 to the promoter regions of responsive genes in cells. In addition, A18 can reduce tumor growth in a mouse xenograft model of lung cancer with little effect on body weight. Taken together, we conclude that it is feasible to inhibit STAT3 by targeting its DNA-binding domain for discovery of anticancer therapeutics.

No / The orally active microtubule-disrupting agent (S)-1-ethyl-3-(2-methoxy-4-(5-methyl-4-((1-(pyridin-3-yl)butyl)amino)pyrimidin-2- yl)phenyl)urea (CYT997), reported previously by us (Bioorg Med Chem Lett 19:4639-4642, 2009; Mol Cancer Ther 8:3036-3045, 2009), is potently cytotoxic to a variety of cancer cell lines in vitro and shows antitumor activity in vivo. In addition to its cytotoxic activity, CYT997 possesses antivascular effects on tumor vasculature. To further characterize the vascular disrupting activity of CYT997 in terms of dose and temporal effects, we studied the activity of the compound on endothelial cells in vitro and on tumor blood flow in vivo by using a variety of techniques. In vitro, CYT997 is shown to potently inhibit the proliferation of vascular endothelial growth factor-stimulated human umbilical vein endothelial cells (IC(50) 3.7 +/- 1.8 nM) and cause significant morphological changes at 100 nM, including membrane blebbing. Using the method of corrosion casting visualized with scanning electron microscopy, a single dose of CYT997 (7.5 mg/kg i.p.) in a metastatic cancer model was shown to cause destruction of tumor microvasculature in metastatic lesions. Furthermore, repeat dosing of CYT997 at 10 mg/kg and above (intraperitoneally, b.i.d.) was shown to effectively inhibit development of liver metastases. The time and dose dependence of the antivascular effects were studied in a DLD-1 colon adenocarcinoma xenograft model using the fluorescent dye Hoechst 33342. CYT997 demonstrated rapid and dose-dependent vascular shutdown, which persists for more than 24 h after a single oral dose. Together, the data demonstrate that CYT997 possesses potent antivascular activity and support continuing development of this promising compound.

No / OBJECTIVE: Development of treatment resistance and adverse toxicity associated with classical chemotherapeutic agents highlights the need for safer and effective therapeutic approaches. Herein, we examined the effectiveness of a combination treatment regimen of 5-fluorouracil (5-FU) and curcumin in colorectal cancer (CRC) cells. METHODS: Wild type HCT116 cells and HCT116+ch3 cells (complemented with chromosome 3) were treated with curcumin and 5-FU in a time- and dose-dependent manner and evaluated by cell proliferation assays, DAPI staining, transmission electron microscopy, cell cycle analysis and immunoblotting for key signaling proteins. RESULTS: The individual IC50 of curcumin and 5-FU were approximately 20 microM and 5 microM in HCT116 cells and 5 microM and 1 microM in HCT116+ch3 cells, respectively (p<0.05). Pretreatment with curcumin significantly reduced survival in both cells; HCT116+ch3 cells were considerably more sensitive to treatment with curcumin and/or 5-FU than wild-type HCT116 cells. The IC50 values for combination treatment were approximately 5 microM and 1 microM in HCT116 and 5 microM and 0.1 microM in HCT116+ch3, respectively (p<0.05). Curcumin induced apoptosis in both cells by inducing mitochondrial degeneration and cytochrome c release. Cell cycle analysis revealed that the anti-proliferative effect of curcumin and/or 5-FU was preceded by accumulation of CRC cells in the S cell cycle phase and induction of apoptosis. Curcumin potentiated 5-FU-induced expression or cleavage of pro-apoptotic proteins (caspase-8, -9, -3, PARP and Bax), and down-regulated anti-apoptotic (Bcl-xL) and proliferative (cyclin D1) proteins. Although 5-FU activated NF-kappaB/PI-3K/Src pathway in CRC cells, this was down-regulated by curcumin treatment through inhibition of IkappaBalpha kinase activation and IkappaBalpha phosphorylation. CONCLUSIONS: Combining curcumin with conventional chemotherapeutic agents such as 5-FU could provide more effective treatment strategies against chemoresistant colon cancer cells. The mechanisms involved may be mediated via NF-kappaB/PI-3K/Src pathways and NF-kappaB regulated gene products.

No / We identify cytochrome P450 1A1 (CYP1A1) as a target for tumor-selective drug development in bladder cancer and describe the characterization of ICT2700, designed to be metabolized from a prodrug to a potent cytotoxin selectively by CYP1A1. Elevated CYP1A1 expression was shown in human bladder cancer relative to normal human tissues. RT112 bladder cancer cells, endogenously expressing CYP1A1, were selectively chemosensitive to ICT2700, whereas EJ138 bladder cells that do not express CYP1A1 were significantly less responsive. Introduction of CYP1A1 into EJ138 cells resulted in 75-fold increased chemosensitivity to ICT2700 relative to wild-type EJ138. Negligible chemosensitivity was observed in ICT2700 in EJ138 cells expressing CYP1A2 or with exposure of EJ138 cells to CYP1B1- or CYP3A4-generated metabolites of ICT2700. Chemosensitivity to ICT2700 was also negated in EJ138-CYP1A1 cells by the CYP1 inhibitor alpha-naphthoflavone. Furthermore, ICT2700 did not induce expression of the AhR-regulated CYP1 family, indicating that constitutive CYP1A1 expression is sufficient for activation of ICT2700. Consistent with the selective activity by CYP1A1 was a time and concentration-dependent increase in gamma-H2AX protein expression, indicative of DNA damage, associated with the activation of ICT2700 in RT112 but not EJ138 cells. In mice-bearing CYP1A1-positive and negative isogenic tumors, ICT2700 administration resulted in an antitumor response only in the CYP1A1-expressing tumor model. This antitumor response was associated with detection of the CYP1A1-activated metabolite in tumors but not in the liver. Our findings support the further development of ICT2700 as a tumor-selective treatment for human bladder cancers.

Yes / Topoisomerase inhibitors are in common use as chemotherapeutic agents although they can display reduced efficacy in chemotherapy-resistant tumours, which have inactivated DNA damage response (DDR) genes, such as ATM and TP53. Here, we characterise the cellular response to the dual-acting agent, Alchemix (ALX), which is a modified anthraquinone that functions as a topoisomerase inhibitor as well as an alkylating agent. We show that ALX induces a robust DDR at nano-molar concentrations and this is mediated primarily through ATR- and DNA-PK- but not ATM-dependent pathways, despite DNA double strand breaks being generated after prolonged exposure to the drug. Interestingly, exposure of epithelial tumour cell lines to ALX in vitro resulted in potent activation of the G2/M checkpoint, which after a prolonged arrest, was bypassed allowing cells to progress into mitosis where they ultimately died by mitotic catastrophe. We also observed effective killing of lymphoid tumour cell lines in vitro following exposure to ALX, although, in contrast, this tended to occur via activation of a p53-independent apoptotic pathway. Lastly, we validate the effectiveness of ALX as a chemotherapeutic agent in vivo by demonstrating its ability to cause a significant reduction in tumour cell growth, irrespective of TP53 status, using a mouse leukaemia xenograft model. Taken together, these data demonstrate that ALX, through its dual action as an alkylating agent and topoisomerase inhibitor, represents a novel anti-cancer agent that could be potentially used clinically to treat refractory or relapsed tumours, particularly those harbouring mutations in DDR genes.

Indiana University-Purdue University Indianapolis (IUPUI) / ALDH isoenzymes are known to impact the sensitivity of certain neoplastic cells toward cyclophosphamides and its analogs. Despite its bone marrow toxicity, cyclophos-phamide is still used to treat various recalcitrant forms of cancer. When activated, cyclo-phosphamide forms aldophosphamide that can spontaneously form the toxic phospho-ramide mustard, an alkylating agent unless detoxified by ALDH isozymes to the carbox-yphosphamide metabolite. Prior work has demonstrated that the ALDH1A1 and ALDH3A1 isoenzymes can convert aldophosphamide to carboxyphosphamide. This has also been verified by over expression and siRNA knockdown studies. Selective small molecule inhibitors for these ALDH isoenzymes are not currently available. We hypothe-sized that novel and selective small molecule inhibitors of ALDH3A1 would enhance cancer cells’ sensitivity toward cyclophosphamide. If successful, this approach can widen the therapeutic treatment window for cyclophosphamides; permitting lower effective dos-ing regimens with reduced toxicity. An esterase based absorbance assay was optimized in a high throughput setting and 101, 000 compounds were screened and two new selective inhibitors for ALDH3A1, which have IC50 values of 0.2 µM (CB7) and 16 µM (CB29) were discovered. These two compounds compete for aldehyde binding, which was vali-dated both by kinetic and crystallographic studies. Structure activity relationship dataset has helped us determine the basis of potency and selectivity of these compounds towards ALDH3A1 activity. Our data is further supported by mafosfamide (an analog of cyclo-phosphamide) chemosensitivity data, performed on lung adenocarcinoma (A549) and gli-oblastoma (SF767) cell lines. Overall, I have identified two compounds, which inhibit ALDH3A1’s dehydrogenase activity selectively and increases sensitization of ALDH3A1 positive cells to aldophosphamide and its analogs. This may have the potential in improving chemotherapeutic efficacy of cyclophosphamide as well as to help us understand better the role of ALDH3A1 in cells. Future work will focus on testing these compounds on other cancer cell lines that involve ALDH3A1 expression as a mode of chemoresistance.