-
Angewandte Chemie (International Ed. in... Mar 2017Anaerobic bacteria, such as Clostridium and Salmonella, can selectively invade and colonize in tumor hypoxic regions (THRs) and deliver therapeutic products to destroy...
Anaerobic bacteria, such as Clostridium and Salmonella, can selectively invade and colonize in tumor hypoxic regions (THRs) and deliver therapeutic products to destroy cancer cells. Herein, we present an anaerobe nanovesicle mimic that can not only be activated in THRs but also induce hypoxia in tumors by themselves. Moreover, inspired by the oxygen metabolism of anaerobes, we construct a light-induced hypoxia-responsive modality to promote dissociation of vehicles and activation of bioreductive prodrugs simultaneously. In vitro and in vivo experiments indicate that this anaerobe-inspired nanovesicle can efficiently induce apoptotic cell death and significantly inhibit tumor growth. Our work provides a new strategy for engineering stimuli-responsive drug delivery systems in a bioinspired and synergistic fashion.
Topics: Antineoplastic Agents; Cell Death; Cell Proliferation; Clostridium; Drug Carriers; Drug Delivery Systems; Drug Screening Assays, Antitumor; Humans; Hypoxia; Imidazoles; Nanoparticles; Prodrugs; Salmonella; Tirapazamine
PubMed: 28140504
DOI: 10.1002/anie.201611783 -
Clinical Cancer Research : An Official... Apr 2005Relapse of neuroblastoma commonly occurs in hypoxic tissues, and is associated with an acquired and sustained high-level drug resistance, often due to p53 loss of... (Comparative Study)
Comparative Study
Relapse of neuroblastoma commonly occurs in hypoxic tissues, and is associated with an acquired and sustained high-level drug resistance, often due to p53 loss of function. Abrogating p53 function with HPV 16 E6 transduction in drug-sensitive neuroblastoma cell lines caused high-level drug resistance. Tirapazamine (TPZ) is a bioreductive agent that forms a toxic free radical in hypoxia. We determined in six neuroblastoma cell lines the cytotoxicity of TPZ using DIMSCAN, a digital imaging fluorescence assay, apoptosis and mitochondrial membrane potential (DeltaPsim) by flow cytometry, and protein expression by immunoblotting. TPZ exhibited high cytotoxicity, especially in hypoxia (2% O2), for all four p53-functional neuroblastoma cell lines, achieving >3 logs of cell kill (LC99 < or = 0.7 microg/mL). In p53-nonfunctional neuroblastoma cell lines, all TPZ LC99 values were >3.0 microg/mL (average clinically achievable level). TPZ (24 hours) induced apoptosis in >46% of cells in p53-functional cell lines but failed to cause apoptosis in p53 nonfunctional cell lines. Induction of p53 and p21 expression by TPZ was observed in a p53-functional cell line (SMS-SAN) but not in a p53-nonfunctional cell line (CHLA-90). Significant DeltaPsim loss and glutathione (GSH) depletion in response to TPZ was observed in p53-functional cell lines (SMS-SAN, SMS-SAN EV, and CHLA-15) but not in p53-nonfunctional cell lines (SMS-SAN E6 and CHLA-90). N-Acetylcysteine inhibited TPZ-mediated DeltaPsim loss and GSH depletion, but neither N-acetylcysteine nor Boc-d-fmk inhibited apoptosis caused by TPZ. In response to TPZ, DeltaPsim loss preceded apoptosis. Thus, TPZ cytotoxicity for neuroblastoma cell lines in hypoxia occurred via a p53-dependent mitochondrial pathway that caused induction of p53 and p21, DeltaPsim decrease, GSH depletion, and apoptosis. These data further define the mechanism of action of TPZ and suggest that as a single agent, TPZ would only have clinical activity against p53-functional neuroblastomas.
Topics: Antineoplastic Agents; Apoptosis; Benzyl Compounds; Blotting, Western; Caspase Inhibitors; Cell Cycle Proteins; Cell Line, Tumor; Cell Survival; Cyclin-Dependent Kinase Inhibitor p21; Dose-Response Relationship, Drug; Flow Cytometry; Glutathione; Humans; Hydrocarbons, Fluorinated; Intracellular Membranes; Membrane Potentials; Mitochondria; Neuroblastoma; Proto-Oncogene Proteins c-bcl-2; Tirapazamine; Triazines; Tumor Suppressor Protein p53; bcl-2-Associated X Protein; bcl-X Protein
PubMed: 15814660
DOI: 10.1158/1078-0432.CCR-04-2382 -
The British Journal of Surgery Apr 2012Radiofrequency ablation (RFA) is a common procedure for the management of colorectal liver metastases. RFA-generated lesions are surrounded by a rim of hypoxia that is...
BACKGROUND
Radiofrequency ablation (RFA) is a common procedure for the management of colorectal liver metastases. RFA-generated lesions are surrounded by a rim of hypoxia that is associated with aggressive outgrowth of intrahepatic micrometastases. Hypoxia-activated prodrugs such as tirapazamine are designed selectively to induce apoptosis in tumour cells under hypoxic conditions. Therefore, it was hypothesized that tirapazamine may have therapeutic value in limiting hypoxia-associated tumour outgrowth following RFA.
METHODS
Murine C26 and MC38 colorectal cancer cells were grown under hypoxia and normal oxygenation in vitro, and treated with different concentrations of tirapazamine. Apoptosis and cell cycle distribution were assessed by western blot and fluorescence-activated cell sorting analysis. Proliferative capacity was tested by means of colony-formation assays. Mice harbouring microscopic colorectal liver metastases were treated with RFA, followed by a single injection of tirapazamine (60 mg/kg) or saline. Tumour load was assessed morphometrically 7 days later.
RESULTS
Tirapazamine induced apoptosis of colorectal tumour cells under hypoxia in vitro. Under normal oxygenation, tirapazamine caused a G2 cell cycle arrest from which cells recovered partly. This reduced, but did not abolish, colony-forming capacity. A single dose of tirapazamine largely prevented accelerated outgrowth of hypoxic micrometastases following RFA. Tirapazamine administration was associated with minimal toxicity.
CONCLUSION
Tirapazamine induced apoptosis in colorectal cancer cells in a hypoxia-dependent manner and potently suppressed hypoxia-associated outgrowth of liver metastases with limited toxicity. This warrants further study to assess the potential value of tirapazamine, or other hypoxia-activated prodrugs, as adjuvant therapeutics following RFA treatment of colorectal liver metastases.
Topics: Animals; Antineoplastic Agents; Apoptosis; Blotting, Western; Catheter Ablation; Cell Hypoxia; Colorectal Neoplasms; Flow Cytometry; Liver Neoplasms; Liver Neoplasms, Experimental; Male; Mice; Mice, Inbred BALB C; Neoplasm Transplantation; Prodrugs; Tirapazamine; Triazines; Tumor Cells, Cultured
PubMed: 22331808
DOI: 10.1002/bjs.8668 -
Basic & Clinical Pharmacology &... Sep 2016Tirapazamine is a hypoxia-activated prodrug which was shown to exhibit up to 300 times greater cytotoxicity under anoxic in comparison with aerobic conditions. Thus, the...
Tirapazamine is a hypoxia-activated prodrug which was shown to exhibit up to 300 times greater cytotoxicity under anoxic in comparison with aerobic conditions. Thus, the combined anticancer therapy of tirapazamine with a routinely used anticancer drug seems to be a promising solution. Because tirapazamine undergoes redox cycle transformation in this study, the effect of tirapazamine on redox hepatic equilibrium, lipid status and liver morphology was evaluated in rats exposed to cisplatin, doxorubicin and 5-fluorouracil. Rats were intraperitoneally injected with tirapazamine and a particular cytostatic. The animals were killed, and blood and liver were collected. Hepatic glucose, total cholesterol, triglycerides, NADH, NADPH glutathione and the activity of glucose-6-phosphate dehydrogenase were determined. Liver morphology and the immune expression of HMG-CoA-reductase were also assessed. Glucose, total cholesterol, triglycerides, bilirubin concentrations and the activity of aspartate and alanine aminotransferases were determined in the plasma. Tirapazamine displayed insignificant interactions with cisplatin and 5-fluorouracil referring to hepatic morphology and biochemical parameters. However, tirapazamine interacts with doxorubicin, thus leading to side changes in redox equilibrium and lipid peroxidation, but those effects are not severe enough to exclude that drug combination from further studies. Thus, tirapazamine seems to be a promising agent in successive studies on anticancer activity in similar schedules.
Topics: Alanine Transaminase; Animals; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Aspartate Aminotransferases; Cholesterol; Cisplatin; Doxorubicin; Drug Interactions; Fluorouracil; Glutathione; Lipid Peroxidation; Liver; Male; Oxidation-Reduction; Rats; Rats, Wistar; Tirapazamine; Triazines; Triglycerides
PubMed: 26990033
DOI: 10.1111/bcpt.12576 -
Clinical Cancer Research : An Official... Jun 2005The level of hypoxia in primary tumors has been linked both clinically and experimentally to the incidence of metastases. This study was designed to address the effect... (Comparative Study)
Comparative Study
PURPOSE
The level of hypoxia in primary tumors has been linked both clinically and experimentally to the incidence of metastases. This study was designed to address the effect of selectively targeting hypoxic cells in primary tumors on subsequent presentation of metastasis.
EXPERIMENTAL DESIGN
The murine KHT model was used as a reproducible temporal and spatial onset of metastases is revealed following treatment of primary ( approximately 400 mm(3)) s.c. tumors with a 25 Gy radiation dose. The bioreductive drugs tirapazamine and RB6145 were administered in multiple doses before radiotherapy.
RESULTS
Fractionated treatment with both tirapazamine and RB6145 significantly reduced the hypoxic fraction of the primary tumor, as assessed by pimonidazole binding, and had no effect on the overall growth rate of the primary tumor. Excision assays showed an increased level of cell kill in tirapazamine-treated versus RB6145-treated tumors consistent with tirapazamine targeting hypoxic cells at a broader range of oxygen tensions than RB6145. Tirapazamine treatment significantly reduced the presentation of metastases following radiotherapy (P = 0.003 versus saline controls) whereas RB6145 had no effect. Local control rates increased from 20% to 32% and 50% when radiation was combined with RB6145 and tirapazamine, respectively.
CONCLUSIONS
These data provide direct evidence that selective targeting of hypoxic cells in primary tumors is a viable approach in the control of metastatic disease. The enhanced efficacy of tirapazamine versus RB6145 suggests that the radioresistant cells at intermediate oxygen tensions, conducive to targeting with tirapazamine but not with the more stringent bioreductive RB6145, predominate in terms of linking primary tumor hypoxia and metastases.
Topics: Animals; Antineoplastic Agents; Cell Line, Tumor; Combined Modality Therapy; Female; Hypoxia; Mice; Mice, Inbred C3H; Neoadjuvant Therapy; Neoplasm Metastasis; Neoplasm Transplantation; Neovascularization, Pathologic; Nitroimidazoles; Radiation-Sensitizing Agents; Sarcoma, Experimental; Tirapazamine; Treatment Outcome; Triazines
PubMed: 15930359
DOI: 10.1158/1078-0432.CCR-04-2162 -
National Science Review Apr 2024Tirapazamine (TPZ) has been approved for multiple clinical trials relying on its excellent anticancer potential. However, as a typical hypoxia-activated prodrug (HAP),...
Tirapazamine (TPZ) has been approved for multiple clinical trials relying on its excellent anticancer potential. However, as a typical hypoxia-activated prodrug (HAP), TPZ did not exhibit survival advantages in Phase III clinical trials when used in combination therapy due to the insufficient hypoxia levels in patients' tumors. In this study, to improve the therapeutic effects of TPZ, we first introduced urea to synthesize a series of urea-containing derivatives of TPZ. All urea-containing TPZ derivatives showed increased hypoxic cytotoxicity (9.51-30.85-fold) compared with TPZ, while maintaining hypoxic selectivity. TPZP, one of these derivatives, showed 20-fold higher cytotoxicity than TPZ while maintaining a similar hypoxic cytotoxicity ratio. To highly efficiently deliver TPZP to the tumors and reduce its side effects on healthy tissues, we further prepared TPZP into a nanodrug with fibrin-targeting ability: FT11-TPZP-NPs. CA4-NPs, a vascular disrupting agent, was used to increase the fibrin level within tumors and exacerbate tumor hypoxia. By being combined with CA4-NPs, FT11-TPZP-NPs can accumulate in the hypoxia-aggravated tumors and activate sufficiently to kill tumor cells. After a single-dose treatment, FT11-TPZP-NPs + CA4-NPs showed a high inhibition rate of 98.1% against CT26 tumor models with an initial volume of ∼480 mm and four out of six tumors were completely eliminated; it thereby exerted a significant antitumor effect. This study provides a new strategy for improving the therapeutic effect of TPZ and other HAPs in anticancer therapy.
PubMed: 38440219
DOI: 10.1093/nsr/nwae038 -
Chemical Research in Toxicology Feb 2017Tirapazamine (TPZ) is an anticancer drug with highly selective cytotoxicity toward hypoxic cells. TPZ is converted to a radical intermediate under hypoxic conditions,...
Tirapazamine (TPZ) is an anticancer drug with highly selective cytotoxicity toward hypoxic cells. TPZ is converted to a radical intermediate under hypoxic conditions, and this intermediate interacts with intracellular macromolecules, including DNA. TPZ has been reported to indirectly induce DNA double-strand breaks (DSBs) through the formation of various intermediate DNA lesions under hypoxic conditions. Although the topoisomerase II-DNA complex has been identified as one of these intermediates, other lesions have not yet been defined. In order to obtain a deeper understanding of the mechanisms responsible for the selective cytotoxicity of TPZ toward hypoxic cells, its cellular sensitivity was systematically examined with genetically isogenic DNA-repair-deficient mutant DT40 cell lines. Our results showed that tdp1, tdp2, parp1, and aptx1 cells displayed hypersensitivity to TPZ only under hypoxic conditions. These results strongly suggest that the accumulation of the topoisomerase I-trapped DNA complex, topoisomerase II-trapped DNA complex, and abortive ligation products with 5'-AMP are the potential causes of TPZ-induced hypoxic cell death. Furthermore, our genetic analysis revealed that under normoxic conditions (as well as hypoxic conditions), TPZ exhibited significant cytotoxicity toward cell lines deficient in homologous recombination, nonhomologous end joining, base excision repair, and translesion synthesis. Ascorbic acid, a radical scavenger, suppressed TPZ-induced cytotoxicity toward normoxic cells. These results suggest the involvement of oxidative DNA damage and DSBs produced by reactive oxygen species generated from superoxide, a byproduct of the oxidation of TPZ radical intermediates in normoxic cells. Collectively, our results demonstrate that TPZ induces oxidative DNA damage under normoxic and hypoxic conditions and selectively introduces abortive topoisomerase-DNA complexes and unligatable DNA ends under hypoxic conditions.
Topics: Animals; Antineoplastic Agents; Cell Line; Chickens; Comet Assay; DNA; DNA Damage; Reactive Oxygen Species; Tirapazamine; Triazines
PubMed: 27943678
DOI: 10.1021/acs.chemrestox.6b00417 -
British Journal of Cancer Apr 1996Tirapazamine (SR 4233), a bioreductive drug selectively toxic towards hypoxic cells, is presently in phase II clinical trials. Since it would not be expected that all...
Tirapazamine (SR 4233), a bioreductive drug selectively toxic towards hypoxic cells, is presently in phase II clinical trials. Since it would not be expected that all tumours would respond equally to the drug, we are exploring ways of predicting the response of individual tumours. In this study we have tested whether the comet assay, which measures DNA damage in individual cells, can provide a simple, surrogate end point for cell killing by tirapazamine. We examined the relationship between the cytotoxicity of tirapazamine under hypoxic conditions and tirapazamine-induced DNA strand breaks in murine (SCCVII, EMT6, RIF-1) and human (HT1080, A549, HT29) tumour cell lines. These results were compared with the relationship between tirapazamine cytotoxicity and another measure of the ability of cells to metabolise tirapazamine; high-performance liquid chromatography (HPLC) analysis of tirapazamine loss or formation of the two electron reduction product SR 4317. The correlation between the hypoxic cytotoxic potency of tirapazamine and DNA damage was highly significant (r = 0.905, P = 0.013). A similar correlation was observed for hypoxic potency and tirapazamine loss (r = 0.812, P = 0.050), while the correlation between hypoxic potency and SR 4317 formation was not significant (r = 0.634, P = 0.171). The hypoxic cytotoxicity of tirapazamine in vitro can therefore be predicted by measuring tirapazamine-induced DNA damage using the comet assay. This approach holds promise for predicting the response of individual tumours to tirapazamine in the clinic.
Topics: Antineoplastic Agents; Cell Division; Cell Hypoxia; Chromatography, High Pressure Liquid; DNA; DNA Damage; Humans; Tirapazamine; Triazines; Tumor Cells, Cultured
PubMed: 8611431
DOI: 10.1038/bjc.1996.187 -
Nanotechnology Aug 2021The therapeutic effect of oxygen-concentration-dependent photodynamic therapy (PDT) can be diminished in the hypoxic environment of solid tumours, the effective solution...
The therapeutic effect of oxygen-concentration-dependent photodynamic therapy (PDT) can be diminished in the hypoxic environment of solid tumours, the effective solution to this problem is utilising hypoxic-activated bioreduction therapy (BRT). In this research, a biocompatible HA-C60/TPENHnanogel which can specifically bind to CD44 receptor was developed for highly efficient PDT-BRT synergistic therapy. The nanogel was degradable in acidic microenvironments of tumours and facilitated the release of biological reduction prodrug tirapazamine (TPZ). Importantly, HA-C60/TPENHnanogel produced reactive oxygen species and consumed oxygen content in the cell to activate TPZ, leading to higher cytotoxicity than the free TPZ did. The intracellular observation of nanogel indicated that the HA-C60/TPENHnanogel was self-fluorescence for cell imaging. This study applied PDT-BRT to design smart HA-based nanogel with targeted delivery, pH response, and AIEgen feature for efficient cancer therapy.
Topics: Antineoplastic Agents; Cell Line; Cell Line, Tumor; Fullerenes; HEK293 Cells; Hep G2 Cells; Humans; Hyaluronan Receptors; Hyaluronic Acid; Hypoxia; Nanogels; Nanoparticles; Photochemotherapy; Photosensitizing Agents; Polyethylene Glycols; Polyethyleneimine; Prodrugs; Reactive Oxygen Species; Tirapazamine; Tumor Microenvironment
PubMed: 34325415
DOI: 10.1088/1361-6528/ac18da -
Microvascular Research Mar 2008We have previously reported that the hypoxic cytotoxin tirapazamine causes central vascular dysfunction in HCT-116 xenografts. Here we further extend this finding to...
We have previously reported that the hypoxic cytotoxin tirapazamine causes central vascular dysfunction in HCT-116 xenografts. Here we further extend this finding to SiHa xenografts and SCCVII murine tumors. Within 1 day after treatment with tirapazamine both tumor types develop areas of non-perfused tissue in central regions of tumors. To explore the mechanism by which the hypoxic cytotoxin tirapazamine causes vascular dysfunction we altered the blood oxygen content with carbogen (95% O(2) and 5% CO(2)) breathing in tumor bearing mice. Carbogen treatment was able to decrease the number of tumors responding to tirapazamine but was not able to eradicate the vascular dysfunction completely. In complementary in vitro studies, immunohistochemical staining of tirapazamine-treated endothelial cells indicated that, unlike the vascular targeting agent (VTA) combretastatin-A-4-phosphate, the vascular effects caused by tirapazamine are not due to microtubule disruption. Another possible mechanism of action for tirapazamine could involve its ability to inhibit nitric oxide synthase (NOS). Studies combining other vascular targeting agents (VTAs) such as the combretastatins have shown a potentiation of vascular disruption in tumors when combined with NOS inhibitors, possibly due to vessel constriction from decreased nitric oxide (NO) levels. We propose the theory that vascular dysfunction caused by tirapazamine may be via NOS inhibition. In support of this hypothesis preliminary experiments showed NOS inhibition with L-NNA (N-omega-nitro-L-arginine) increases tumor necrosis, 1 day after administration, in our HCT-116 tumor model.
Topics: Animals; Antineoplastic Agents; Carbon Dioxide; Cell Hypoxia; Cells, Cultured; Dose-Response Relationship, Drug; Endothelial Cells; Endothelium, Vascular; Enzyme Inhibitors; HCT116 Cells; Humans; Mice; Mice, Inbred C3H; Mice, Inbred NOD; Mice, SCID; Necrosis; Neoplasms, Experimental; Nitric Oxide Synthase; Nitroarginine; Oxygen; Regional Blood Flow; Time Factors; Tirapazamine; Triazines
PubMed: 18023823
DOI: 10.1016/j.mvr.2007.09.006