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PloS One 2015In spite of the tremendous efforts dedicated to developing hypoxia-activated prodrugs, no agents yet have been approved for clinical therapy. In the present study, the...
In spite of the tremendous efforts dedicated to developing hypoxia-activated prodrugs, no agents yet have been approved for clinical therapy. In the present study, the hypoxic selective anti-cancer activity as well as the cellular target of a novel tirapazamine (TPZ) analogue, 7-methyl-3-(3-chlorophenyl)-quinoxaline-2-carbonitrile 1,4-dioxide (Q6) were investigated. Q6 implemented anti-cancer effects via poisoning topoisomerase II (topo II) under hypoxia. Modified trapped in agarose DNA immunostaining (TARDIS) assay showed more topo II-DNA cleavage complexes trapped by Q6 than TPZ at even lower concentration. In addition, by introducing ataxia-telangiectasia-mutated (ATM) kinase inhibitors caffeine and KU-60019, we displayed that Q6-triggered apoptosis was attributed, at least partially, to DNA double-strand breaks generated by the topo II-targeting effect. Collectively, Q6 stood out for its better hypoxia-selectivity and topo II-poisoning than the parental compound TPZ. All these data shed light on the research of Q6 as a promising hypoxia-activated prodrug candidate for human hepatocellular carcinoma therapy.
Topics: Apoptosis; Carcinoma, Hepatocellular; Cell Line, Tumor; Drug Delivery Systems; Humans; Hypoxia; Liver Neoplasms; Morpholines; Thioxanthenes; Topoisomerase II Inhibitors
PubMed: 26649750
DOI: 10.1371/journal.pone.0144506 -
European Journal of Nuclear Medicine... Apr 2016While methods for imaging tumor hypoxia with positron emission tomography (PET) have been developed, optimal methods for interpreting and utilizing these datasets in the... (Comparative Study)
Comparative Study
Quantitative and qualitative analysis of [(18)F]FDG and [(18)F]FAZA positron emission tomography of head and neck cancers and associations with HPV status and treatment outcome.
PURPOSE
While methods for imaging tumor hypoxia with positron emission tomography (PET) have been developed, optimal methods for interpreting and utilizing these datasets in the clinic remain unclear. In this study, we analyzed hypoxia PET images of head and neck cancer patients and compared imaging metrics with human papilloma virus (HPV) status and clinical outcome.
METHODS
Forty-one patients treated as part of a phase III trial of the hypoxic cytotoxin tirapazamine (TROG 02.02) were imaged with PET using fluorodeoxyglucose (FDG) and fluoroazomycin arabinoside (FAZA). FDG and FAZA PET images were interpreted qualitatively and quantitatively, and compared with tumor T stage, HPV status, and treatment outcome using multivariate statistics.
RESULTS
PET signals in the tumor and lymph nodes exhibited significant intra- and inter-patient variability. The FAZA hypoxic volume demonstrated a significant correlation with tumor T stage. PET-hypoxic tumors treated with cisplatin exhibited significantly worse treatment outcomes relative to PET-oxic tumors or PET-hypoxic tumors treated with tirapazamine.
CONCLUSION
Quantitative analysis of FAZA PET yielded metrics that correlated with clinical T stage and were capable of stratifying patient outcome. These results encourage further development of this technology, with particular emphasis on establishment of robust quantitative methods.
Topics: Adult; Aged; Data Interpretation, Statistical; Female; Fluorodeoxyglucose F18; Head and Neck Neoplasms; Humans; Male; Middle Aged; Nitroimidazoles; Papillomavirus Infections; Positron-Emission Tomography; Radiopharmaceuticals
PubMed: 26577940
DOI: 10.1007/s00259-015-3247-7 -
PloS One 2015Quinoxaline 1,4-di-N-oxides (QdNOs) are widely known as potent antibacterial agents, but their antibacterial mechanisms are incompletely understood. In this study, the...
Quinoxaline 1,4-di-N-oxides (QdNOs) are widely known as potent antibacterial agents, but their antibacterial mechanisms are incompletely understood. In this study, the transcriptomic and proteomic profiles of Escherichia coli exposed to QdNOs were integratively investigated, and the results demonstrated that QdNOs mainly induced an SOS response and oxidative stress. Moreover, genes and proteins involved in the bacterial metabolism, cellular structure maintenance, resistance and virulence were also found to be changed, conferring bacterial survival strategies. Biochemical assays showed that reactive oxygen species were induced in the QdNO-treated bacteria and that free radical scavengers attenuated the antibacterial action of QdNOs and DNA damage, suggesting an oxidative-DNA-damage action of QdNOs. The QdNO radical intermediates, likely carbon-centered and aryl-type radicals, as identified by electron paramagnetic resonance, were the major radicals induced by QdNOs, and xanthine oxidase was one of the QdNO-activating enzymes. This study provides new insights into the action of QdNOs in a systematic manner and increases the current knowledge of bacterial physiology under antibiotic stresses, which may be of great value in the development of new antibiotic-potentiating strategies.
Topics: Anti-Bacterial Agents; Cell Survival; DNA Damage; Dose-Response Relationship, Drug; Escherichia coli; Gene Expression Regulation, Bacterial; Microbial Sensitivity Tests; Molecular Sequence Annotation; Oxidation-Reduction; Oxidative Stress; Protein Biosynthesis; Proteomics; Quinoxalines; Reactive Oxygen Species; SOS Response, Genetics; Structure-Activity Relationship; Tirapazamine; Triazines
PubMed: 26296207
DOI: 10.1371/journal.pone.0136450 -
Proceedings of the National Academy of... Jul 2015Free radical attack on the C1' position of DNA deoxyribose generates the oxidized abasic (AP) site 2-deoxyribonolactone (dL). Upon encountering dL, AP lyase enzymes such...
Free radical attack on the C1' position of DNA deoxyribose generates the oxidized abasic (AP) site 2-deoxyribonolactone (dL). Upon encountering dL, AP lyase enzymes such as DNA polymerase β (Polβ) form dead-end, covalent intermediates in vitro during attempted DNA repair. However, the conditions that lead to the in vivo formation of such DNA-protein cross-links (DPC), and their impact on cellular functions, have remained unknown. We adapted an immuno-slot blot approach to detect oxidative Polβ-DPC in vivo. Treatment of mammalian cells with genotoxic oxidants that generate dL in DNA led to the formation of Polβ-DPC in vivo. In a dose-dependent fashion, Polβ-DPC were detected in MDA-MB-231 human cells treated with the antitumor drug tirapazamine (TPZ; much more Polβ-DPC under 1% O2 than under 21% O2) and even more robustly with the "chemical nuclease" 1,10-copper-ortho-phenanthroline, Cu(OP)2. Mouse embryonic fibroblasts challenged with TPZ or Cu(OP)2 also incurred Polβ-DPC. Nonoxidative agents did not generate Polβ-DPC. The cross-linking in vivo was clearly a result of the base excision DNA repair pathway: oxidative Polβ-DPC depended on the Ape1 AP endonuclease, which generates the Polβ lyase substrate, and they required the essential lysine-72 in the Polβ lyase active site. Oxidative Polβ-DPC had an unexpectedly short half-life (∼ 30 min) in both human and mouse cells, and their removal was dependent on the proteasome. Proteasome inhibition under Cu(OP)2 treatment was significantly more cytotoxic to cells expressing wild-type Polβ than to cells with the lyase-defective form. That observation underscores the genotoxic potential of oxidative Polβ-DPC and the biological pressure to repair them.
Topics: Animals; Cell Line, Tumor; DNA; DNA Damage; DNA Polymerase beta; Humans; Mice; Oxidation-Reduction
PubMed: 26124145
DOI: 10.1073/pnas.1501101112 -
Anti-cancer Agents in Medicinal... 20143-(Aminoalkylamino)-1,2,4-benzotriazine-1,4-dioxide-extended derivatives were synthesized by the structural modification of 3-amino-1,2,4-benzotriazine-1,4-dioxide...
Synthesis, preferentially hypoxic apoptosis and anti-angiogenic activity of 1,2,4-benzotrazin-3-amine 1,4-dioxide bearing alkyl linkers with 1,2,4-benzotrazin-3-amine 1-oxide derivatives.
3-(Aminoalkylamino)-1,2,4-benzotriazine-1,4-dioxide-extended derivatives were synthesized by the structural modification of 3-amino-1,2,4-benzotriazine-1,4-dioxide (tirapazamine, TPZ) that incorporated homologue-alkyl linkers, without or with an extended 3- amino-1,2,4-benzotriazine-1-oxide moiety at the 3-position of the TPZ. According to sequential evaluation of preferentially normoxic and hypoxic cytotoxicities against MCF-7, NCI-H460 and HCT-116, most of the synthesized compounds exhibited hypoxic cytotoxicity greater than or comparable to that of TPZ. Among them, compounds 9a and 9b more powerfully inhibited the proliferation of MCF-7, NCI-H460 and HCT-116 in hypoxia than did TPZ. The representative of 3-(aminoalkylamino)-1,2,4-benzotriazine-1,4-dioxide-extended derivatives, 9a exhibited greater hypoxic cytotoxicity than TPZ, mediated by cell cycle arrest. The induction of DNA damage, the activation of caspase 3/7 and cleaved poly(ADP-ribose) polymerase-related apoptosis, which were detected in HCT-116 cells in both normoxia and hypoxia. In vitro anti-angiogenic assay of co-cultured HUVECs and fibroblasts that were exposed to the selected 7b, 8g, 9a and 9b exhibited 80-90% inhibition of tube formation at 20 µM, whereas TPZ exhibited approximately 50% inhibition of tube formation at 20 µM. At 2 µM, 9a and 9b significantly reduced the areas, lengths, paths and joints of tube formation by 70-80% and 45-50%, respectively. These results reveal that most of synthesized TPZ derivatives in this study exhibited more potent anti-angiogenesis than TPZ.
PubMed: 25312508
DOI: 10.2174/1871520614666141014130554 -
The Journal of Organic Chemistry Aug 2014Tirapazamine (3-amino-1,2,4-benzotriazine 1,4-dioxide) is a heterocyclic di-N-oxide that undergoes enzymatic deoxygenation selectively in the oxygen-poor (hypoxic) cells...
Toward hypoxia-selective DNA-alkylating agents built by grafting nitrogen mustards onto the bioreductively activated, hypoxia-selective DNA-oxidizing agent 3-amino-1,2,4-benzotriazine 1,4-dioxide (tirapazamine).
Tirapazamine (3-amino-1,2,4-benzotriazine 1,4-dioxide) is a heterocyclic di-N-oxide that undergoes enzymatic deoxygenation selectively in the oxygen-poor (hypoxic) cells found in solid tumors to generate a mono-N-oxide metabolite. This work explored the idea that the electronic changes resulting from the metabolic deoxygenation of tirapazamine analogues might be exploited to activate a DNA-alkylating species selectively in hypoxic tissue. Toward this end, tirapazamine analogues bearing nitrogen mustard units were prepared. In the case of the tirapazamine analogue 18a bearing a nitrogen mustard unit at the 6-position, it was found that removal of the 4-oxide from the parent di-N-oxide to generate the mono-N-oxide analogue 17a did indeed cause a substantial increase in reactivity of the mustard unit, as measured by hydrolysis rates and DNA-alkylation yields. Hammett sigma values were measured to quantitatively assess the magnitude of the electronic changes induced by metabolic deoxygenation of the 3-amino-1,2,4-benzotriazine 1,4-dioxide heterocycle. The results provide evidence that the 1,2,4-benzotiazine 1,4-dioxide unit can serve as an oxygen-sensing prodrug platform for the selective unmasking of bioactive agents in hypoxic cells.
Topics: Alkylating Agents; Antineoplastic Agents; Cyclic N-Oxides; DNA Damage; Gas Chromatography-Mass Spectrometry; Hypoxia; Mechlorethamine; Molecular Structure; Oxidation-Reduction; Prodrugs; Tirapazamine; Triazines
PubMed: 25029663
DOI: 10.1021/jo501252p -
Frontiers in Oncology Dec 2013Hypoxia contributes to resistance of tumors to some cytotoxic drugs and to radiotherapy, but can in principle be exploited with hypoxia-activated prodrugs (HAP). HAP in... (Review)
Review
Hypoxia contributes to resistance of tumors to some cytotoxic drugs and to radiotherapy, but can in principle be exploited with hypoxia-activated prodrugs (HAP). HAP in clinical development fall into two broad groups. Class I HAP (like the benzotriazine N-oxides tirapazamine and SN30000), are activated under relatively mild hypoxia. In contrast, Class II HAP (such as the nitro compounds PR-104A or TH-302) are maximally activated only under extreme hypoxia, but their active metabolites (effectors) diffuse to cells at intermediate O2 and thus also eliminate moderately hypoxic cells. Here, we use a spatially resolved pharmacokinetic/pharmacodynamic (SR-PK/PD) model to compare these two strategies and to identify the features required in an optimal Class II HAP. The model uses a Green's function approach to calculate spatial and longitudinal gradients of O2, prodrug, and effector concentrations, and resulting killing in a digitized 3D tumor microregion to estimate activity as monotherapy and in combination with radiotherapy. An analogous model for a normal tissue with mild hypoxia and short intervessel distances (based on a cremaster muscle microvessel network) was used to estimate tumor selectivity of cell killing. This showed that Class II HAP offer advantages over Class I including higher tumor selectivity and greater freedom to vary prodrug diffusibility and rate of metabolic activation. The model suggests that the largest gains in class II HAP antitumor activity could be realized by optimizing effector stability and prodrug activation rates. We also use the model to show that diffusion of effector into blood vessels is unlikely to materially increase systemic exposure for realistic tumor burdens and effector clearances. However, we show that the tumor selectivity achievable by hypoxia-dependent prodrug activation alone is limited if dose-limiting normal tissues are even mildly hypoxic.
PubMed: 24409417
DOI: 10.3389/fonc.2013.00314 -
Journal of Clinical Oncology : Official... Feb 2014This prospective, randomized phase III intergroup trial of the Gynecologic Oncology Group and National Cancer Institute of Canada Clinical Trials Group was designed to... (Comparative Study)
Comparative Study Randomized Controlled Trial
Phase III randomized trial of weekly cisplatin and irradiation versus cisplatin and tirapazamine and irradiation in stages IB2, IIA, IIB, IIIB, and IVA cervical carcinoma limited to the pelvis: a Gynecologic Oncology Group study.
PURPOSE
This prospective, randomized phase III intergroup trial of the Gynecologic Oncology Group and National Cancer Institute of Canada Clinical Trials Group was designed to test the effectiveness and safety of adding the hypoxic cell sensitizer tirapazamine (TPZ) to standard cisplatin (CIS) chemoradiotherapy in locally advanced cervix cancer.
PATIENTS AND METHODS
Patients with locally advanced cervix cancer were randomly assigned to CIS chemoradiotherapy versus CIS/TPZ chemoradiotherapy. Primary end point was progression-free survival (PFS). Secondary end points included overall survival (OS) and tolerability.
RESULTS
PFS was evaluable in 387 of 402 patients randomly assigned over 36 months, with enrollment ending in September 2009. Because of the lack of TPZ supply, the study did not reach its original target accrual goal. At median follow-up of 28.3 months, PFS and OS were similar in both arms. Three-year PFS for the TPZ/CIS/RT and CIS/RT arms were 63.0% and 64.4%, respectively (log-rank P = .7869). Three-year OS for the TPZ/CIS/RT and CIS/RT arms were 70.5% and 70.6%, respectively (log-rank P = .8333). A scheduled interim safety analysis led to a reduction in the starting dose for the TPZ/CIS arm, with resulting tolerance in both treatment arms.
CONCLUSION
TPZ/CIS chemoradiotherapy was not superior to CIS chemoradiotherapy in either PFS or OS, although definitive commentary was limited by an inadequate number of events (progression or death). TPZ/CIS chemoradiotherapy was tolerable at a modified starting dose.
Topics: Adenocarcinoma; Adult; Aged; Antineoplastic Combined Chemotherapy Protocols; Canada; Carcinoma, Adenosquamous; Carcinoma, Squamous Cell; Chemoradiotherapy; Chi-Square Distribution; Cisplatin; Disease Progression; Disease-Free Survival; Female; Humans; Kaplan-Meier Estimate; Middle Aged; Neoplasm Staging; Proportional Hazards Models; Prospective Studies; Time Factors; Tirapazamine; Treatment Outcome; Triazines; United States; Uterine Cervical Neoplasms
PubMed: 24395863
DOI: 10.1200/JCO.2013.51.4265 -
Molecules (Basel, Switzerland) Dec 2013In this work, a sensitive analytical method to study the stability of two new series of synthesized heterocyclic compounds, the benzimidazole-4,7-diones 5 and N-oxide...
In this work, a sensitive analytical method to study the stability of two new series of synthesized heterocyclic compounds, the benzimidazole-4,7-diones 5 and N-oxide benzimidazole-4,7-dione derivatives 6 was established and validated. These derivatives were developed as potential anticancer substances to be activated under hypoxic conditions. At this point we were concerned with establishing their stability in some specific environments for further biological studies. For that, we developed and validated an RP-UPLC method. Next, selected compounds were tested in vitro for possible anticancer activity. Their effect on A549 tumour cell lines under normoxia and hypoxia conditions was determined by a WST-1 test. Four of the examined compounds (compounds 5a-c and 6c) showed very good antiproliferative effects and three of them (compounds 6a, 6b and 6d) were specific for hypoxia conditions. The hypoxia/normoxia cytotoxic coefficient of compound 6b is close to that of tirapazamine--a reference compound in our experiments--and this parameter locates it between mitomycin C and 2-nitroimidazole (misonidazole).
Topics: Antineoplastic Agents; Benzimidazoles; Cell Hypoxia; Cell Line, Tumor; Cell Proliferation; Chromatography, Liquid; Drug Stability; Humans; Inhibitory Concentration 50; Molecular Structure; Reproducibility of Results; Structure-Activity Relationship
PubMed: 24384922
DOI: 10.3390/molecules19010400 -
PloS One 2013Many cancer research efforts focus on exploiting genetic-level features that may be targeted for therapy. Tissue-level features of the tumour microenvironment also...
Many cancer research efforts focus on exploiting genetic-level features that may be targeted for therapy. Tissue-level features of the tumour microenvironment also represent useful therapeutic targets. Here we investigate the presence of low oxygen tension and sensitivity to NOS inhibition of tumour vasculature as potential tumour-specific features that may be targeted by hypoxic cytotoxins, a class of therapeutics currently under investigation. We have previously demonstrated that tirapazamine (TPZ) mediates central vascular dysfunction in tumours. TPZ is a hypoxic cytotoxin that is also a competitive inhibitor of NOS. Here we further investigated the vascular-targeting activity of TPZ by combining it with NOS inhibitor L-NNA, or with low oxygen content gas breathing. Tumours were analyzed via multiplex immunohistochemical staining that revealed irreversible loss of perfusion and enhanced tumour cell death when TPZ was combined with either low oxygen or a NOS inhibitor. Tumour growth rate was reduced by TPZ + NOS inhibition, and tumours previously resistant to TPZ-mediated vascular dysfunction were sensitized by low oxygen breathing. Additional mapping analysis suggests that tumours with reduced vascular-associated stroma may have greater sensitivity to these effects. These results indicate that poorly oxygenated tumour vessels, also being abnormally organized and with inadequate smooth muscle, may be successfully targeted for significant anti-cancer effects by inhibition of NOS and hypoxia-activated prodrug toxicity. This strategy illustrates a novel use of hypoxia-activated cytotoxic prodrugs as vascular targeting agents, and also represents a novel mechanism for targeting tumour vessels.
Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Cell Line, Tumor; Cytotoxins; Female; HCT116 Cells; HT29 Cells; Humans; Hypoxia; Immunohistochemistry; Mice; Mice, Inbred C3H; Mice, Inbred NOD; Mice, SCID; Neoplasms; Neovascularization, Pathologic; Nitric Oxide Synthase; Nitroarginine; Tirapazamine; Treatment Outcome; Triazines; Tumor Burden; Xenograft Model Antitumor Assays
PubMed: 24204680
DOI: 10.1371/journal.pone.0076832