Singlet oxygen is among the reactive oxygen species (ROS) with the shortest life‐times in aqueous media because of its extremely high reactivity. Therefore, designing sensors for detection of 1O2 is ...perhaps one of the most challenging tasks in the field of molecular probes. Herein, we report a highly selective and sensitive chemiluminescence probe (SOCL‐CPP) for the detection of 1O2 in living cells. The probe reacts with 1O2 to form a dioxetane that spontaneously decomposes under physiological conditions through a chemiexcitation pathway to emit green light with extraordinary intensity. SOCL‐CPP demonstrated promising ability to detect and image intracellular 1O2 produced by a photosensitizer in HeLa cells during photodynamic therapy (PDT) mode of action. Our findings make SOCL‐CPP the most effective known chemiluminescence probe for the detection of 1O2. We anticipate that our chemiluminescence probe for 1O2 imaging would be useful in PDT‐related applications and for monitoring 1O2 endogenously generated by cells in response to different stimuli.
Illuminating singlet oxygen: A chemiluminescence probe for singlet oxygen based on dioxetane formation is described. The dioxetane decomposes through a highly efficient chemiexcitation process to emit green light. The probe was used to detect and image intracellular 1O2 produced by a photosensitizer in HeLa cells during photodynamic therapy.
The majority of theranostic prodrugs reported so far relay information through a fluorogenic response generated upon release of the active chemotherapeutic agent. A chemiluminescence detection mode ...offers significant advantages over fluorescence, mainly due to the superior signal‐to‐noise ratio of chemiluminescence. Here we report the design and synthesis of the first theranostic prodrug monitored by a chemiluminescence diagnostic mode. As a representative model, we prepared a prodrug from the chemotherapeutic monomethyl auristatin E, which was modified for activation by β‐galactosidase. The activation of the prodrug in the presence of β‐galactosidase is accompanied by emission of a green photon. Light emission intensities, which increase with increasing concentration of the prodrug, were linearly correlated with a decrease in the viability of a human cell line that stably expresses β‐galactosidase. We obtained sharp intravital chemiluminescent images of endogenous enzymatic activity in β‐galactosidase‐overexpressing tumor‐bearing mice. The exceptional sensitivity achieved with the chemiluminescence diagnostic mode should allow the exploitation of theranostic prodrugs for personalized cancer treatment.
Ray of light: A chemiluminescence detection mode offers significant advantages over fluorescence, mainly due to a superior signal‐to‐noise ratio. A theranostic prodrug that is monitored through a chemiluminescence diagnostic mode was designed. As a representative example, a prodrug was prepared from the chemotherapeutic monomethyl auristatin E, which was modified for activation by β‐galactosidase.
The coronavirus disease-19 (COVID-19) is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The long incubation period of this new virus, which is mostly asymptomatic yet ...contagious, is a key reason for its rapid spread across the world. Currently, there is no worldwide-approved treatment for COVID-19. Therefore, the clinical and scientific communities have joint efforts to reduce the severe impact of the outbreak. Research on previous emerging infectious diseases have created valuable knowledge that is being exploited for drug repurposing and accelerated vaccine development. Nevertheless, it is important to generate knowledge on SARS-CoV-2 mechanisms of infection and its impact on host immunity, to guide the design of COVID-19 specific therapeutics and vaccines suitable for mass immunization. Nanoscale delivery systems are expected to play a paramount role in the success of these prophylactic and therapeutic approaches. This Review provides an overview of SARS-CoV-2 pathogenesis and examines immune-mediated approaches currently explored for COVID-19 treatments, with an emphasis on nanotechnological tools.
Chemiluminescence is being considered an effective imaging modality as it offers low background and high sensitivity. Recent discovery by our group has led to development of new phenoxy‐dioxetane ...chemiluminescence luminophores, which are highly bright under physiological conditions. However, the current scope of probes based on these luminophores is limited, as they can only be turned on by phenol protecting group removal. Here we present a new chemiluminescence resonance energy transfer (CRET) system, Glow‐CRET, in which light emission is triggered by proteolytic cleavage of a peptide substrate that links a dioxetane luminophore and a quencher. In order to compose such system, a new phenoxy‐dioxetane luminophore, 7‐HC‐CL, was developed. This luminophore exhibits intense and persistent glow chemiluminescence; it undergoes very slow chemiexcitation, and it has the highest chemiluminescence quantum yield ever reported under physiological conditions. Based on 7‐HC‐CL, a Glow‐CRET probe for matrix metalloproteinases, MMP‐CL, was synthesized. Incubation of MMP‐CL with its cognate protease resulted in 160‐fold increase in chemiluminescence signal. MMP‐CL was also able to detect matrix metalloproteinase activity in cancer cells with significantly higher signal‐to‐background ratio than an analogous fluorescence resonance energy transfer (FRET)‐based probe. This work is expected to open new horizons in chemiluminescence imaging, as it enables to use the dioxetanes in ways that had not been possible. We anticipate that 7‐HC‐CL and future derivatives will be utilized not only for the construction of further Glow‐CRET probes, but also for other applications, such as chemiluminescence tagging of proteins.
Fantastic glow: A remarkable phenoxy‐dioxetane luminophore is described; it undergoes very slow chemiexcitation and has an unrivaled chemiluminescence quantum yield under physiological conditions. With this luminophore, a novel chemiluminescence resonance energy transfer system for the detection of matrix metalloproteinase activity in cancer cells was developed.
A polymer therapeutic designed for combination anticancer and antiangiogenic therapy inhibited the proliferation of prostate carcinoma cells and the proliferation, migration, and tube-formation of ...endothelial cells. The nanoconjugate was formed from an N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer, the bisphosphonate alendronate (for bone targeting), and the chemotherapy agent paclitaxel (PTX), which is cleaved by cathepsin B (see scheme).
Glioblastoma (GB) is the most aggressive neoplasm of the brain. Poor prognosis is mainly attributed to tumor heterogeneity, invasiveness and drug resistance. Only a small fraction of GB patients ...survives longer than 24 months from the time of diagnosis (ie, long-term survivors LTS). In our study, we aimed to identify molecular markers associated with favorable GB prognosis as a basis to develop therapeutic applications to improve patients' outcome. We have recently assembled a proteogenomic dataset of 87 GB clinical samples of varying survival rates. Following RNA-seq and mass spectrometry (MS)-based proteomics analysis, we identified several differentially expressed genes and proteins, including some known cancer-related pathways and some less established that showed higher expression in short-term (<6 months) survivors (STS) compared to LTS. One such target found was deoxyhypusine hydroxylase (DOHH), which is known to be involved in the biosynthesis of hypusine, an unusual amino acid essential for the function of the eukaryotic translation initiation factor 5A (eIF5A), which promotes tumor growth. We consequently validated DOHH overexpression in STS samples by quantitative polymerase chain reaction (qPCR) and immunohistochemistry. We further showed robust inhibition of proliferation, migration and invasion of GB cells following silencing of DOHH with short hairpin RNA (shRNA) or inhibition of its activity with small molecules, ciclopirox and deferiprone. Moreover, DOHH silencing led to significant inhibition of tumor progression and prolonged survival in GB mouse models. Searching for a potential mechanism by which DOHH promotes tumor aggressiveness, we found that it supports the transition of GB cells to a more invasive phenotype via epithelial-mesenchymal transition (EMT)-related pathways.
Glioblastoma (GB) is a highly invasive type of brain cancer exhibiting poor prognosis. As such, its microenvironment plays a crucial role in its progression. Among the brain stromal cells, the ...microglia were shown to facilitate GB invasion and immunosuppression. However, the reciprocal mechanisms by which GB cells alter microglia/macrophages behavior are not fully understood. We propose that these mechanisms involve adhesion molecules such as the Selectins family. These proteins are involved in immune modulation and cancer immunity. We show that P-selectin mediates microglia-enhanced GB proliferation and invasion by altering microglia/macrophages activation state. We demonstrate these findings by pharmacological and molecular inhibition of P-selectin which leads to reduced tumor growth and increased survival in GB mouse models. Our work sheds light on tumor-associated microglia/macrophage function and the mechanisms by which GB cells suppress the immune system and invade the brain, paving the way to exploit P-selectin as a target for GB therapy.
New targets for RNA interference (RNAi)-based cancer therapy are constantly emerging from the increasing knowledge on key molecular pathways that are paramount for carcinogenesis. Nevertheless, in ...vivo delivery of small interfering RNA (siRNA) remains a crucial challenge for therapeutic success. siRNAs on their own are not taken up by most mammalian cells in a way that preserves their activity. Moreover, when applied in vivo, siRNA-based approaches are all limited by poor penetration into the target tissue and low silencing efficiency. To circumvent these limitations, we have developed novel polymerized polyglycerol-based dendrimer core shell structures to deliver siRNA to tumors in vivo. These cationic dendrimers can strongly improve the stability of the siRNA, its intracellular trafficking, its silencing efficacy, and its accumulation in the tumor environment owing to the enhanced permeability and retention effect. Here, we show that our dendritic nanocarriers exhibited low cytotoxicity and high efficacy in delivering active siRNA into cells. With use of human glioblastoma and murine mammary adenocarcinoma cell lines as model systems, these siRNA-dendrimer polyplexes silenced the luciferase gene, ectopically overexpressed in these cells. Importantly, significant gene silencing was accomplished in vivo within 24 h of treatment with our luciferase siRNA-nanocarrier polyplexes, as measured by noninvasive intravital bioluminescence imaging. Moreover, our siRNA-nanocarriers show very low levels of toxicity as no significant weight loss was observed after intravenous administration of the polyplexes. We show a proof of concept for siRNA delivery in vivo using a luciferase-based model. We predict that in vivo silencing of important cell growth and angiogenesis regulator genes in a selective manner will justify this approach as a successful anticancer therapy.--Ofek, P., Fischer, W., Calderón, M., Haag, R., Satchi-Fainaro, R. In vivo delivery of small interfering RNA to tumors and their vasculature by novel dendritic nanocarriers.
The most common site of breast cancer metastasis is the bone, occurring in approximately 70% of patients with advanced disease. Bone metastasis is associated with severe morbidities and high ...mortality. Therefore, deeper understanding of the mechanisms that enable bone-metastatic relapse are urgently needed. We report the establishment and characterization of a bone-seeking variant of breast cancer cells that spontaneously forms aggressive bone metastases following surgical resection of primary tumor. We characterized the modifications in the immune milieu during early and late stages of metastatic relapse and found that the formation of bone metastases is associated with systemic changes, as well as modifications of the bone microenvironment towards an immune suppressive milieu. Furthermore, we characterized the intrinsic changes in breast cancer cells that facilitate bone-tropism and found that they acquire mesenchymal and osteomimetic features. This model provides a clinically relevant platform to study the functional interactions between breast cancer cells and the bone microenvironment, in an effort to identify novel targets for intervention.
The ability to monitor drug release in vivo provides essential pharmacological information. We developed a new modular approach for the preparation of theranostic prodrugs with a turn-ON ...near-infrared (NIR) fluorescence mode of action. The prodrugs release their chemotherapeutic cargo and an active cyanine fluorophore upon reaction with a specific analyte. The prodrug platform is based on the fluorogenic dye QCy7; upon removal of a triggering substrate, the dye fluoresces, and the free drug is released. The evaluated camptothecin prodrug was activated by endogenous hydrogen peroxide produced in tumor cells in vitro and in vivo. Drug release and in vitro cytotoxicity were correlated with the emitted fluorescence. The prodrug activation was effectively imaged in real time in mice bearing tumors. The modular design of the QCy7 fluorogenic platform should allow the preparation of numerous other prodrugs with various triggering substrates and chemotherapeutic agents. We anticipate that the development of real-time in vivo monitoring tools such as that described herein will pave the way for personalized therapy.
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