Hypoxia-targeting by tirapazamine (TPZ) induces preferential growth inhibition of nasopharyngeal carcinoma cells with Chk1/2 activation

Porphyrin-based covalent organic framework with NIR absorption: Preparation, hyaluronic acid modification, and cascading a hypoxia-sensitive drug for synergistic therapy of cancer phototherapy/chemotherapy

Porphyrins are popular photosensitizers for photodynamic therapy of diseases. However, the poor water solution and short absorption wavelengths of porphyrins limit their clinical application. In this work, a novel worm-like porphyrin covalent organic framework (Por-COF) with excellent dispersibility and near-infrared absorption was prepared via a facile method. First, a pH-responsive macromolecule was prepared using Schiff base bonds between porphyrin and terephthalaldehyde, and the spatial arrangement of macromolecules was controlled to prepare Por-COF. Second, the hypoxia-responsive drug tirapazamine (TPZ) and tumor-targeted hyaluronic acid (HA) were loaded to Por-COF through the electrostatic effect to prepare a multifunction nanomedicine (Por-COF@TPZ/HA) that could simultaneously produce abundant reactive oxygen species and high temperature via808 nm laser irradiation. TPZ was cascaded for the synergistic therapy of cancers. In vitro cytotoxicity showed that the inhibition rate of cell activity in the Por-COF@TPZ/HA + Laser group was 1.2 times higher than that in the Por-COF/HA + Laser group. In vivo experiments also demonstrated that the aggravated tumor hypoxia caused by photodynamic therapy could activate TPZ to achieve high-efficiency chemotherapy. Combined photodynamic-photothermal therapy and chemotherapy had an outstanding synergistic effect. This work provides a promising method for Por-COF preparation and a feasible strategy for the synergistic therapy of cancers.

The combined effect of hypoxia activation and radiosensitization by a multifunctional nanoplatform system enhances the therapeutic efficacy of chemoradiotherapy in pancreatic cancer

BACKGROUND

Pancreatic cancer is a highly malignant tumor, which is still a major global health problem. Chemotherapy and radiotherapy are regularly used in adjuvant therapy for pancreatic cancer but their therapeutic efficacy is limited.

METHODS

In the present study, nanoparticle（MSN-AuNPs） was used as a drug carrier loaded with tirapazamine(TPZ) and hyaluronic acid (HA) to synthesize a multifunctional nanoplatform HA@TPZ-MSN-AuNPs (HTMA) for hypoxia activation and radiotherapy sensitization, which can be combined with radiotherapy therapy and synergistically enhance the therapeutic effect in pancreatic cancer. The anti-tumor performance of the nano platform was verified by in vivo and in vitro experiments.

RESULT

First, the HA@TPZ-MSN-AuNPs (HTMA) was successfully synthesized. Drug release experiments showed that acidic environment and hyaluronidase promoted drug release in the nanoplatform. In vitro experiments, CCK-8, live-dead staining, clonal formation assay and flow cytometry confirmed the combined anti-tumor effect of hypoxia activation and radiotherapy sensitization with HTMA. In the drug uptake experiment, the nanoplatform showed the function of targeting and binding pancreatic cancer cells. In vivo, HTMA demonstrated good antitumor properties and good biocompatibility.

CONCLUSIONS

The nanoplatform had a good targeting effect and synergistic anti-tumor effect. The combination of hypoxia activation and radiotherapy sensitization is a promising strategy for the treatment of pancreatic cancer.

18F-Fluoroazomycin Arabinoside (FAZA) PET/MR as a Biomarker of Hypoxia in Rectal Cancer: A Pilot Study

Tumor hypoxia is a negative prognostic factor in many tumors and is predictive of metastatic spread and poor responsiveness to both chemotherapy and radiotherapy. Purpose: To assess the feasibility of using 18F-Fluoroazomycin arabinoside (FAZA) PET/MR to image tumor hypoxia in patients with locally advanced rectal cancer (LARC) prior to and following neoadjuvant chemoradiotherapy (nCRT). The secondary objective was to compare different reference tissues and thresholds for tumor hypoxia quantification. Patients and Methods: Eight patients with histologically proven LARC were included. All patients underwent 18F-FAZA PET/MR prior to initiation of nCRT, four of whom also had a second scan following completion of nCRT and prior to surgery. Tumors were segmented using T2-weighted MR. Each voxel within the segmented tumor was defined as hypoxic or oxic using thresholds derived from various references: ×1.0 or ×1.2 SUVmean of blood pool [BP] or left ventricle [LV] and SUVmean +3SD for gluteus maximus. Correlation coefficient (CoC) between HF and tumor SUVmax/reference SUVmean TRR for the various thresholds was calculated. Hypoxic fraction (HF), defined as the % hypoxic voxels within the tumor volume was calculated for each reference/threshold. Results: For all cases, baseline and follow-up, the CoCs for gluteus maximus and for BP and LV (×1.0) were 0.241, 0.344, and 0.499, respectively, and HFs were (median; range) 16.6% (2.4-33.8), 36.8% (0.3-72.9), and 30.7% (0.8-55.5), respectively. For a threshold of ×1.2, the CoCs for BP and LV as references were 0.611 and 0.838, respectively, and HFs were (median; range) 10.4% (0-47.6), and 4.3% (0-20.1%), respectively. The change in HF following nCRT ranged from (-18.9%) to (+54%). Conclusions: Imaging of hypoxia in LARC with 18F-FAZA PET/MR is feasible. Blood pool as measured in the LV appears to be the most reliable reference for calculating the HF. There is a wide range of HF and variable change in HF before and after nCRT.

Medicinal Chemistry of Drugs with N-Oxide Functionalities

Molecules with N-oxide functionalities are omnipresent in nature and play an important role in Medicinal Chemistry. They are synthetic or biosynthetic intermediates, prodrugs, drugs, or polymers for applications in drug development and surface engineering. Typically, the N-oxide group is critical for biomedical applications of these molecules. It may provide water solubility or decrease membrane permeability or immunogenicity. In other cases, the N-oxide has a special redox reactivity which is important for drug targeting and/or cytotoxicity. Many of the underlying mechanisms have only recently been discovered, and the number of applications of N-oxides in the healthcare field is rapidly growing. This Perspective article gives a short summary of the properties of N-oxides and their synthesis. It also provides a discussion of current applications of N-oxides in the biomedical field and explains the basic molecular mechanisms responsible for their biological activity.

Sandwich-Structured Implants to Obstruct Multipath Energy Supply and Trigger Self-Enhanced Hypoxia-Initiated Chemotherapy Against Postsurgical Tumor Recurrence and Metastasis

As a currently common strategy to treat cancer, surgical resection may cause tumor recurrence and metastasis due to residual postoperative tumors. Herein, an implantable sandwich-structured dual-drug depot is developed to trigger a self-intensified starvation therapy and hypoxia-induced chemotherapy sequentially. The two outer layers are 3D-printed using a calcium-crosslinked mixture ink containing soy protein isolate, polyvinyl alcohol, sodium alginate, and combretastatin A4 phosphate (CA4P). The inner layer is one patch of poly (lactic-co-glycolic acid)-based electrospun fibers loaded with tirapazamine (TPZ). The preferentially released CA4P destroys the preexisting blood vessels and prevents neovascularization, which obstructs the external energy supply to cancer cells but aggravates hypoxic condition. The subsequently released TPZ is bioreduced to cytotoxic benzotriazinyl under hypoxia, further damaging DNA, generating reactive oxygen species, disrupting mitochondria, and downregulating hypoxia-inducible factor 1α, vascular endothelial growth factor, and matrix metalloproteinase 9. Together these processes induce apoptosis, block the intracellular energy supply, counteract the disadvantage of CA4P in favoring intratumor angiogenesis, and suppress tumor metastasis. The in vivo and in vitro results and the transcriptome analysis demonstrate that the postsurgical adjuvant treatment with the dual-drug-loaded sandwich-like implants efficiently inhibits tumor recurrence and metastasis, showing great potential for clinical translation.

Highly Active Nano-Reactor for Responding Tumor Microenvironment and Antitumor Therapy

The tumor microenvironment is complex and changeable, so the design of a nano-delivery system for the tumor microenvironment has attracted wide attention. Based on this, we designed an intelligent nano-reactor for the characteristics of acidic pH and hypoxia in the tumor microenvironment. Firstly, the silver nano-balls were synthesized by the biological template method, which exhibited a good photothermal conversion efficiency and can realize the photothermal treatment of tumor sites. Subsequently, the hypoxic prodrug tirapazamine (TPZ) and polydopamine (PDA) for chemotherapy were self-assembled. After PDA arrived at the tumor site (pH 5.5) from the normal physiological environment (pH 7.4), the hypoxic prodrug TPZ was released in pH response by PDA. Subsequently, TPZ selectively induced obvious cell damage under tumor hypoxia stimulation but had no toxic effect on normal cells under normal oxygen. In addition, the nano-converter was loaded with iRGD on the surface, which enhanced the targeted delivery of the nano-reactor to achieve a highly effective antitumor effect. The nano-reactor was capable of combining photothermal/chemotherapy therapy. Importantly, it can selectively kill tumor cells without damaging normal cells based on the characteristics of the tumor microenvironment, with high bio-safety and clinical transformation potential.

Targeting Hypoxia: Hypoxia-Activated Prodrugs in Cancer Therapy

Hypoxia is an important characteristic of most solid malignancies, and is closely related to tumor prognosis and therapeutic resistance. Hypoxia is one of the most important factors associated with resistance to conventional radiotherapy and chemotherapy. Therapies targeting tumor hypoxia have attracted considerable attention. Hypoxia-activated prodrugs (HAPs) are bioreductive drugs that are selectively activated under hypoxic conditions and that can accurately target the hypoxic regions of solid tumors. Both single-agent and combined use with other drugs have shown promising antitumor effects. In this review, we discuss the mechanism of action and the current preclinical and clinical progress of several of the most widely used HAPs, summarize their existing problems and shortcomings, and discuss future research prospects.

Pretreatment Photopenia on 18F-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography Scans Predicts Poor Prognosis in Nasopharyngeal Cancer Patients Undergoing Concurrent Chemoradiotherapy

OBJECTIVES

To investigate the influence of pretreatment primary tumor or nodal photopenia (PP) on 18F-fluorodeoxyglucose positron emission tomography-computed tomography (FDG PET-CT), an indicator of tumor ischemia, on survival results of nasopharyngeal cancers (NPCs) treated with concurrent chemoradiotherapy (C-CRT).

METHODS

The pre-C-CRT FDG PET-CT scans of 104 patients with NPC (cT1-4 N0-3 M0) were retrospectively examined to determine the presence of PP (PP+). Our primary endpoint was the influence of PP+ on overall survival (OS), while the progression-free survival (PFS) and locoregional PFS (LRPFS) constituted the secondary endpoints.

RESULTS

The PP+ was detected in 29 (27.9%): nine (8.7%), seven (6.7%), and 13 (12.5%) in the primary tumor alone, primary tumor plus neck nodes, and neck nodes alone, respectively. Because the PP+ cases were small by count per location, all comparative analyses were performed according to overall PP+/ PP- status instead of per detected site. At a median follow-up of 67.8 months (range, 9 to 130 months), the median survival times were not reached (NR) for the entire population, while 5-year OS, LRPFS, and PFS rates were 73.3%, 68.2%, and 63.4%, respectively. Comparatively the PP+ patients exhibited significantly poorer median OS (49.8 months vs. NR, P<0.001), LRPFS (40.7 months vs. NR, P=0.001), and PFS (31.8 months vs. NR, P=0.002) durations than their PP- counterparts. Furthermore, the PP+ retained its independent prognostic significance in multivariate analysis (P<0.001).

CONCLUSION

Present results uncovered the pre-C-CRT PP as an independent predictor of poor prognosis for NPC patients, which underscore the requirement for the fortification of the local and systemic treatments in hypoxic NPCs.

New tirapazamine derivatives protect cardiomyocytes from doxorubicin toxicity

Doxorubicin cardiotoxicity is caused by various mechanisms, most importantly by oxidative stress originating in the mitochondria. Tirapazamine is a hypoxia-activated anticancer experimental drug. Both drugs in normoxia conditions undergo univalent reduction, thus tirapazamine may compete with doxorubicin in univalent reduction enzyme uptake. Herein, tirapazamine derivatives consisted of drug molecules and alkyl chain-connected triphenylphosphine cations that bring about an accumulation in mitochondria. The aim of this study was to evaluate the interaction of newly synthesized tirapazamine derivatives with doxorubicin in rat cardiomyocytes via an vitro model. In the work, H9C2 cells were incubated with combinations of doxorubicin, tirapazamine and seven variants of tirapazamine derivatives. After 24 hours, cell viability was assessed using MTT assay and the results were confirmed by microscopic observation. Tirapazamine in all tested concentrations did not revealed significant protective activity to cardiomyocytes treated with doxorubicine. However, tirapazamine derivatives diminished the cytotoxic effect of doxorubicin regardless of concentration and alkyl chain length. Tirapazamine derivatives have shown protective effects in relation to cardiomyocytes treated with doxorubicin and the mechanism of this phenomenon must be confirmed.

Three-dimensional perfused tumour spheroid model for anti-cancer drug screening

Objective

To build an in vitro-perfused, three-dimensional (3D) spheroid model based on the TissueFlex system for anti-cancer drug efficacy testing in order to mimic avascular micro-tissues with inherent O₂, nutrient and metabolite gradients, and to provide a more accurate prediction of drug toxicity and efficacy than traditional in vitro tumour models in conventional static culture well plates.

Results

The perfused cancer spheroid model showed higher cell viability and increased diameter of spheroids over a relatively long culture period (17 days). Three anti-cancer drugs with different cytotoxic mechanisms were tested. In perfusion, lower cytotoxicity was observed for traditional cytotoxic drug 5-fluorouracil and microtubule-interfering, paclitaxel, showed greater interruption of spheroid integrity. For the hypoxic-dependent drug, tirapazamine, there was no significant difference observed between static and perfusion cultures.

Conclusion

The perfusion culture provides a better homeostasis for cancer cell growth in a more controllable working platform for long-term drug testing.

Electronic supplementary material

The online version of this article (doi:10.1007/s10529-016-2035-1) contains supplementary material, which is available to authorized users.

Genotoxic risk of quinocetone and its possible mechanism in in vitro studies

Quinoxalines possessing the quinoxaline-1,4-dioxide (QdNOs) basic structure are used for their antibacterial action, although their mechanism of genotoxicity is not clear. After comparing the sensitivity of V79 cells and HepG2 cells to quinocetone (QCT) and other QdNOs, it was found that HepG2 cells are more sensitive. The results show that QCT induces the generation of O2˙- and OH˙ during metabolism. Free radicals could then attack guanine and induce 8-hydroxy-deoxyguanine (8-OHdG) generation, causing DNA strand breakage, the inhibition of topoisomerase II (topo II) activity, and alter PCNA, Gadd45 and topo II gene expression. QCT also caused mutations in the mtDNA genes COX1, COX3 and ATP6, which might affect the function of the mitochondrial respiratory chain and increase the production of reactive oxygen species (ROS). Nuclear extracts from HepG2 cells treated with QCT had markedly reduced topo II activity, as judged by the inability to convert pBR322 DNA from the catenated to the decatenated form by producing stable DNA-topo II complexes. This study suggests that QCT electrostatically bound to DNA in a groove, affecting the dissociation of topo II from DNA and impacting DNA replication. Taken together, these data reveal that DNA damage induced by QCT resulted from O2˙- and OH˙ generated in the metabolism process. This data throws new light onto the genotoxicity of quinoxalines.

A Review: Proteomics in Nasopharyngeal Carcinoma

Although radiotherapy is generally effective in the treatment of major nasopharyngeal carcinoma (NPC), this treatment still makes approximately 20% of patients radioresistant. Therefore, the identification of blood or biopsy biomarkers that can predict the treatment response to radioresistance and that can diagnosis early stages of NPC would be highly useful to improve this situation. Proteomics is widely used in NPC for searching biomarkers and comparing differentially expressed proteins. In this review, an overview of proteomics with different samples related to NPC and common proteomics methods was made. In conclusion, identical proteins are sorted as follows: Keratin is ranked the highest followed by such proteins as annexin, heat shock protein, 14-3-3σ, nm-23 protein, cathepsin, heterogeneous nuclear ribonucleoproteins, enolase, triosephosphate isomerase, stathmin, prohibitin, and vimentin. This ranking indicates that these proteins may be NPC-related proteins and have potential value for further studies.

From tumor hypoxia to cancer progression: the implications of hypoxia-inducible factor-1 expression in cancers

Hypoxia, defined as a decrease of tissue oxygen levels, represents a fundamental pathophysiological condition in the microenvironment of solid tumors. Tumor hypoxia is known to be associated with radio/chemo-resistance and metastasis that eventually lead to cancer progression contributing to poor prognosis in cancer patients. Among transcription factors that accumulated under hypoxic conditions, hypoxia-inducible factor-1 (HIF-1) is a master transcription factor that has received the most intense attention in this field of research due to its capacity to modulate several hundred genes. With a clearer understanding of the HIF-1 pathway, efforts are directed at manipulation of this complex genetic process in order to ultimately decrease cellular HIF-1 levels. Some novel agents have been shown to have HIF-1 inhibition activity through a variety of molecular mechanisms and have provided promising results in the preclinical setting.

Tirapazamine-doxorubicin interaction referring to heart oxidative stress and Ca²⁺ balance protein levels

Doxorubicin (DOX) causes long-term cardiomyopathy that is dependent on oxidative stress and contractility disorders. Tirapazamine (TP), an experimental adjuvant drug, passes the same red-ox transformation as DOX. The aim of the study was to evaluate an effect of tirapazamine on oxidative stress, contractile protein level, and cardiomyocyte necrosis in rats administered doxorubicin. Rats were intraperitoneally injected six times once a week with tirapazamine in two doses, 5 (5TP) and 10 mg/kg (10TP), while doxorubicin was administered in dose 1.8 mg/kg (DOX). Subsequent two groups received both drugs simultaneously (5TP+DOX and 10TP+DOX). Tirapazamine reduced heart lipid peroxidation and normalised RyR2 protein level altered by doxorubicin. There were no significant changes in GSH/GSSG ratio, total glutathione, cTnI, AST, and SERCA2 level between DOX and TP+DOX groups. Cardiomyocyte necrosis was observed in groups 10TP and 10TP+DOX.

K252a induces anoikis-sensitization with suppression of cellular migration in Epstein-Barr virus (EBV)--associated nasopharyngeal carcinoma cells

Recent studies revealed an unexpected role of the neurotrophin receptor pathway, BDNF/TrkB signaling, in cancer metastasis and anoikis (i.e. detachment-induced cell death). Survival of cancer cells in detached state (known as anoikis-resistance) is known to be pre-requisite for metastasis. Nasopharyngeal carcinoma (NPC), an endemic head and neck cancer in Southeast Asia, is highly invasive, metastatic, and etiologically associated with Epstein-Barr virus (EBV, an oncovirus) infection. Mechanistic studies on the invasive/metastatic nature of NPC can facilitate the development of anti-metastatic therapy in NPC. Thus far, the role of BDNF/TrkB signaling in virus-associated human cancer is unclear. Here, using multiple cell line models of NPC with EBV-association (HONE-1-EBV, HK1-LMP1 and C666-1), we investigated the potential involvement of BDNF/TrkB signaling in cellular migration and anoikis-resistant characteristics of NPC. We found that all three EBV-associated NPC cell lines tested were intrinsically anoikis-resistant (i.e. survived in detached state) and expressed both BDNF and TrkB. BDNF stimulation induced cellular migration, but not proliferation of these cells. Further, we examined if pharmacologic targeting of anoikis-resistance of NPC cells can be achievable by a proof-of-concept Trk inhibitor, K252a, in these EBV-associated NPC models. Our results demonstrated that K252a, was able to attenuate BDNF-induced migration and proliferation of NPC cells. More importantly, we demonstrated for the first time that K252a harbored potent anoikis-sensitization activity (i.e. sensitizing cancer cells to detachment-induced cell death) against EBV-associated human cancer cells, namely NPC cells. This proof-of-concept study demonstrated that K252a, a Trk inhibitor, can potentially be used as an anoikis-sensitizing agent in NPC.