Biomarkers and molecular probes for cell death imaging and targeted therapeutics

Red/NIR-I-Fluorescence Carbon Dots Based on Rhein with Active Oxygen Scavenging and Colitis Targeting for UC Therapeutics

Ulcerative colitis (UC) is a chronic inflammatory disease with uncontrolled inflammation and demage to the intestinal barrier. Rhein, a bioactive compound in traditional Chinese medicine, has anti-inflammatory and intestinal repair effect. However, their clinical application is limited by their hydrophobicity and poor bioavailability. L-arginine, as a complement to NO, has synergistic and attenuating effects. In this paper, red/NIR-I fluorescent carbon dots based on rhein and doped with L-arginine (RA-CDs), which are synthesized by a hydrothermal process without any organic solvents, are reported. RA-CDs preserve a portion of the functional group of the active precursor, increase rhein solubility, and emit red/NIR-I light for biological imaging. In vitro experiments show that RA-CDs scavenge excessive reactive oxygen species (ROS), protect cells from oxidative stress, and enable the fluorescence imaging of inflamed colons. In a DSS-induced UC mouse model, both delayed and prophylactic treatment with RA-CDs via intraperitoneal and tail vein injections alleviate UC severity by reducing intestinal inflammation and restoring the intestinal barrier. This study highlights a novel strategy for treating and imaging UC with poorly soluble small-molecule drugs.

New Advances in the Exploration of Esterases with PET and Fluorescent Probes

Esterases are hydrolases that catalyze the hydrolysis of esters into the corresponding acids and alcohols. The development of fluorescent probes for detecting esterases is of great importance due to their wide spectrum of biological and industrial applications. These probes can provide a rapid and sensitive method for detecting the presence and activity of esterases in various samples, including biological fluids, food products, and environmental samples. Fluorescent probes can also be used for monitoring the effects of drugs and environmental toxins on esterase activity, as well as to study the functions and mechanisms of these enzymes in several biological systems. Additionally, fluorescent probes can be designed to selectively target specific types of esterases, such as those found in pathogenic bacteria or cancer cells. In this review, we summarize the recent fluorescent probes described for the visualization of cell viability and some applications for in vivo imaging. On the other hand, positron emission tomography (PET) is a nuclear-based molecular imaging modality of great value for studying the activity of enzymes in vivo. We provide some examples of PET probes for imaging acetylcholinesterases and butyrylcholinesterases in the brain, which are valuable tools for diagnosing dementia and monitoring the effects of anticholinergic drugs on the central nervous system.

Transmembrane potential, an indicator in situ reporting cellular senescence and stress response in plant tissues

BACKGROUND

Plant cells usually sustain a stable membrane potential due to influx and/or efflux of charged ions across plasma membrane. With the growth and development of plants, different tissues and cells undergo systemic or local programmed decline. Whether the membrane potential of plasma membrane could report senescence signal of plant tissues and cells is unclear.

RESULTS

We applied a maneuverable transmembrane potential (TMP) detection method with patch-clamp setup to examine the senescence signal of leaf tissue cells in situ over the whole life cycle in Arabidopsis thaliana. The data showed that the TMPs of plant tissues and cells were varied at different growth stages, and the change of TMP was higher at the vegetative growth stage than at the reproductive stage of plant growth. The distinct change of TMP was detectable between the normal and the senescent tissues and cells in several plant species. Moreover, diverse abiotic stimuli, such as heat stress, hyperpolarized the TMP in a short time, followed by depolarized membrane potential with the senescence occurring. We further examined the TMP of plant chloroplasts, which also indicates the senescence signal in organelles.

CONCLUSIONS

This convenient TMP detection method can report the senescence signal of plant tissues and cells, and can also indicate the potential of plant tolerance to environmental stress.

Beta HPV Deregulates Double-Strand Break Repair

Beta human papillomavirus (beta HPV) infections are common in adults. Certain types of beta HPVs are associated with nonmelanoma skin cancer (NMSC) in immunocompromised individuals. However, whether beta HPV infections promote NMSC in the immunocompetent population is unclear. They have been hypothesized to increase genomic instability stemming from ultraviolet light exposure by disrupting DNA damage responses. Implicit in this hypothesis is that the virus encodes one or more proteins that impair DNA repair signaling. Fluorescence-based reporters, next-generation sequencing, and animal models have been used to test this primarily in cells expressing beta HPV E6/E7. Of the two, beta HPV E6 appears to have the greatest ability to increase UV mutagenesis, by attenuating two major double-strand break (DSB) repair pathways, homologous recombination, and non-homologous end-joining. Here, we review this dysregulation of DSB repair and emerging approaches that can be used to further these efforts.

Nano-Theranostics for the Sensing, Imaging and Therapy of Prostate Cancers

We highlight hereby recent developments in the emerging field of theranostics, which encompasses the combination of therapeutics and diagnostics in a single entity aimed for an early-stage diagnosis, image-guided therapy as well as evaluation of therapeutic outcomes of relevance to prostate cancer (PCa). Prostate cancer is one of the most common malignancies in men and a frequent cause of male cancer death. As such, this overview is concerned with recent developments in imaging and sensing of relevance to prostate cancer diagnosis and therapeutic monitoring. A major advantage for the effective treatment of PCa is an early diagnosis that would provide information for an appropriate treatment. Several imaging techniques are being developed to diagnose and monitor different stages of cancer in general, and patient stratification is particularly relevant for PCa. Hybrid imaging techniques applicable for diagnosis combine complementary structural and morphological information to enhance resolution and sensitivity of imaging. The focus of this review is to sum up some of the most recent advances in the nanotechnological approaches to the sensing and treatment of prostate cancer (PCa). Targeted imaging using nanoparticles, radiotracers and biomarkers could result to a more specialised and personalised diagnosis and treatment of PCa. A myriad of reports has been published literature proposing methods to detect and treat PCa using nanoparticles but the number of techniques approved for clinical use is relatively small. Another facet of this report is on reviewing aspects of the role of functional nanoparticles in multimodality imaging therapy considering recent developments in simultaneous PET-MRI (Positron Emission Tomography-Magnetic Resonance Imaging) coupled with optical imaging in vitro and in vivo, whilst highlighting feasible case studies that hold promise for the next generation of dual modality medical imaging of PCa. It is envisaged that progress in the field of imaging and sensing domains, taken together, could benefit from the biomedical implementation of new synthetic platforms such as metal complexes and functional materials supported on organic molecular species, which can be conjugated to targeting biomolecules and encompass adaptable and versatile molecular architectures. Furthermore, we include hereby an overview of aspects of biosensing methods aimed to tackle PCa: prostate biomarkers such as Prostate Specific Antigen (PSA) have been incorporated into synthetic platforms and explored in the context of sensing and imaging applications in preclinical investigations for the early detection of PCa. Finally, some of the societal concerns around nanotechnology being used for the detection of PCa are considered and addressed together with the concerns about the toxicity of nanoparticles–these were aspects of recent lively debates that currently hamper the clinical advancements of nano-theranostics. The publications survey conducted for this review includes, to the best of our knowledge, some of the most recent relevant literature examples from the state-of-the-art. Highlighting these advances would be of interest to the biomedical research community aiming to advance the application of theranostics particularly in PCa diagnosis and treatment, but also to those interested in the development of new probes and methodologies for the simultaneous imaging and therapy monitoring employed for PCa targeting.

The Emerging Role of Ultrasonic Nanotechnology for Diagnosing and Treatment of Diseases

Nanotechnology has been commonly used in a variety of applications in recent years. Nanomedicine has also gotten a lot of attention in the medical and treatment fields. Ultrasonic technology is already being used in research as a powerful tool for manufacturing nonmaterial and in the decoration of catalyst supports for energy applications and material processing. For the development of nanoparticles and the decoration of catalytic assisted powders with nanoparticles, low or high-frequency Ultrasonic are used. The Ultrasonic is frequently used in joint venture with the nanotechnology from the past few years and bring tremendous success in various diseases diagnosing and treatment. Numerous kinds of nanoparticles are fabricated with desired capabilities and targeted toward different targets. This review first highlights the Ultrasonic Treatment and processing of Nanoparticles for Pharmaceuticals. Next, we explain various nanoparticles with ultrasonic technology for different diagnosing and treatment of various diseases. Finally, we explain the challenges face by current approaches for their translation in clinics.

Development of Duramycin-Based Molecular Probes for Cell Death Imaging

Cell death is involved in numerous pathological conditions such as cardiovascular disorders, ischemic stroke and organ transplant rejection, and plays a critical role in the treatment of cancer. Cell death imaging can serve as a noninvasive means to detect the severity of tissue damage, monitor the progression of diseases, and evaluate the effectiveness of treatments, which help to provide prognostic information and guide the formulation of individualized treatment plans. The high abundance of phosphatidylethanolamine (PE), which is predominantly confined to the inner leaflet of the lipid bilayer membrane in healthy mammalian cells, becomes exposed on the cell surface in the early stages of apoptosis or accessible to the extracellular milieu when the cell suffers from necrosis, thus representing an attractive target for cell death imaging. Duramycin is a tetracyclic polypeptide that contains 19 amino acids and can bind to PE with excellent affinity and specificity. Additionally, this peptide has several favorable structural traits including relatively low molecular weight, stability to enzymatic hydrolysis, and ease of conjugation and labeling. All these highlight the potential of duramycin as a candidate ligand for developing PE-specific molecular probes. By far, a couple of duramycin-based molecular probes such as Tc-99 m-, F-18-, or Ga-68-labeled duramycin have been developed to target exposed PE for in vivo noninvasive imaging of cell death in different animal models. In this review article, we describe the state of the art with respect to in vivo imaging of cell death using duramycin-based molecular probes, as validated by immunohistopathology.

Interest and Limits of [18F]ML-10 PET Imaging for Early Detection of Response to Conventional Chemotherapy

One of the current challenges in oncology is to develop imaging tools to early detect the response to conventional chemotherapy and adjust treatment strategies when necessary. Several studies evaluating PET imaging with 2-deoxy-2-[¹⁸F]fluoro-D-glucose ([¹⁸F]FDG) as a predictive tool of therapeutic response highlighted its insufficient specificity and sensitivity. The [¹⁸F]FDG uptake reflects only tumor metabolic activity and not treatment-induced cell death, which seems to be relevant for therapeutic evaluation. Therefore, to evaluate this parameter in vivo, several cell death radiotracers have been developed in the last years. However, few of them have reached the clinical trials. This systematic review focuses on the use of [¹⁸F]ML-10 (2-(5-[¹⁸F]fluoropentyl)-2-methylmalonic acid) as radiotracer of apoptosis and especially as a measure of tumor response to treatment. A comprehensive literature review concerning the preclinical and clinical investigations conducted with [¹⁸F]ML-10 was performed. The abilities and applications of this radiotracer as well as its clinical relevance and limitations were discussed. Most studies highlighted a good ability of the radiotracer to target apoptotic cells. However, the increase in apoptosis during treatment did not correlate with the radiotracer tumoral uptake, even using more advanced image analysis (voxel-based analysis). [¹⁸F]ML-10 PET imaging does not meet current clinical expectations for early detection of the therapeutic response to conventional chemotherapy. This review has pointed out the challenges of applying various apoptosis imaging strategies in clinical trials, the current methodologies available for image analysis and the future of molecular imaging to assess this therapeutic response.

An Activatable Near-Infrared Fluorescence Probe for in Vivo Imaging of Acute Kidney Injury by Targeting Phosphatidylserine and Caspase-3

Renal-clearable and target-responsive near-infrared (NIR) fluorescent imaging probes have been promising for in vivo diagnosis of acute kidney injury (AKI). However, designing an imaging probe that is renal-clearable and concurrently responsive toward multiple molecular targets to facilitate early detection of AKI with improved sensitivity and specificity is challenging. Herein, by leveraging the receptor-mediated binding and retention effect along with enzyme-triggered fluorescence activation, we design and synthesize an activatable small-molecule NIR fluorescent probe (1-DPA2) using a "one-pot sequential click reaction" approach. 1-DPA2 can target both the externalized phosphatidylserine (PS) and active caspase-3 (Casp-3), two essential biomarkers of apoptosis, producing enhanced 808 nm NIR fluorescence and a high signal-to-background ratio (SBR) amenable to detecting the onset of cisplatin-induced AKI in mice as early as 24 h post-treatment with cisplatin. We not only monitor the gradual activation of Casp-3 in the kidney of mice upon AKI progression but also can report on the progressive recovery of kidney functions in AKI mice following N-acetyl-l-cysteine (NAC) therapy via real-time fluorescence imaging by 1-DPA2. This study demonstrates the ability of 1-DPA2 for longitudinal monitoring of renal cell apoptosis by concurrently targeting PS externalization and Casp-3 activation, which is efficient for early diagnosis of AKI and useful for prediction of potential drug nephrotoxicity as well as in vivo screening of anti-AKI drugs' efficacy.

Novel phosphatidylserine-binding molecule enhances antitumor T-cell responses by targeting immunosuppressive exosomes in human tumor microenvironments

Background

The human tumor microenvironment (TME) is a complex and dynamic milieu of diverse acellular and cellular components, creating an immunosuppressive environment, which contributes to tumor progression. We have previously shown that phosphatidylserine (PS) expressed on the surface of exosomes isolated from human TMEs is causally linked to T-cell immunosuppression, representing a potential immunotherapeutic target. In this study, we investigated the effect of ExoBlock, a novel PS-binding molecule, on T-cell responses in the TME.

Methods

We designed and synthesized a new compound, (ZnDPA)₆-DP-15K, a multivalent PS binder named ExoBlock. The PS-binding avidity of ExoBlock was tested using an in vitro competition assay. The ability of this molecule to reverse exosome-mediated immunosuppression in vitro was tested using human T-cell activation assays. The in vivo therapeutic efficacy of ExoBlock was then tested in two different human tumor xenograft models, the melanoma-based xenomimetic (X-)mouse model, and the ovarian tumor-based omental tumor xenograft (OTX) model.

Results

ExoBlock was able to bind PS with high avidity and was found to consistently and significantly block the immunosuppressive activity of human ovarian tumor and melanoma-associated exosomes in vitro. ExoBlock was also able to significantly enhance T cell-mediated tumor suppression in vivo in both the X-mouse and the OTX model. In the X-mouse model, ExoBlock suppressed tumor recurrence in a T cell-dependent manner. In the OTX model, ExoBlock treatment resulted in an increase in the number as well as function of CD4 and CD8 T cells in the TME, which was associated with a reduction in tumor burden and metastasis, as well as in the number of circulating PS+ exosomes in tumor-bearing mice.

Conclusion

Our results establish that targeting exosomal PS in TMEs with ExoBlock represents a promising strategy to enhance antitumor T-cell responses.

Positron Emission Tomographic Imaging of Tumor Cell Death Using Zirconium-89-Labeled APOMAB® Following Cisplatin Chemotherapy in Lung and Ovarian Cancer Xenograft Models

PURPOSE

Early detection of tumor treatment responses represents an unmet clinical need with no approved noninvasive methods. DAB4, or its chimeric derivative, chDAB4 (APOMAB®) is an antibody that targets the Lupus associated antigen (La/SSB). La/SSB is over-expressed in malignancy and selectively targeted by chDAB4 in cancer cells dying from DNA-damaging treatment. Therefore, chDAB4 is a unique diagnostic tool that detects dead cancer cells and thus could distinguish between treatment responsive and nonresponsive patients.

PROCEDURES

In clinically relevant tumor models, mice bearing subcutaneous xenografts of human ovarian or lung cancer cell lines or intraperitoneal ovarian cancer xenografts were untreated or given chemotherapy followed 24h later by chDAB4 radiolabeled with [⁸⁹Zr]Zr^IV. Tumor responses were monitored using bioluminescence imaging and caliper measurements. [⁸⁹Zr]Zr-chDAB4 uptake in tumor and normal tissues was measured using an Albira SI Positron-Emission Tomography (PET) imager and its biodistribution was measured using a Hidex gamma-counter.

RESULTS

Tumor uptake of [⁸⁹Zr]Zr-chDAB4 was detected in untreated mice, and uptake significantly increased in both human lung and ovarian tumors after chemotherapy, but not in normal tissues.

CONCLUSION

Given that tumors, rather than normal tissues, were targeted after chemotherapy, these results support the clinical development of chDAB4 as a radiodiagnostic imaging agent and as a potential predictive marker of treatment response.

Induction of apoptosis by Kola nut extract as a recent and promising treatment strategy for Leukemia

Kola nut extracts have recently been reported to contain chemopreventive compounds providing several pharmacological benefits. This study investigated Kola nut extracts' anti-cancer activity on human immortalized myelogenous leukemia cell line K562 through apoptosis and cell cycle arrest. Fresh Kola nuts were prepared as powder and dissolved in DMSO. Different concentrations (50, 100, 150, 200, and 250 μg/ml) of working solutions were prepared. The K562 cells were treated with the different concentrations of Kola nut extract or vehicle control (10% DMSO) followed by incubation at 37°C for 24, 48, and 72 hours, respectively. Treatment activity was investigated in K562 cells; by Resazurin, and FITC/Propidium Iodide and 7-AAD stained cells to evaluate apoptotic cells and the cell cycle's progression. Inhibition of leukemia cell proliferation was observed. The extract effectively induced cell death, early and late apoptosis by approximately 30% after 24 and 48 hours incubation, and an increase in the rate of dead cells by 50% was observed after 72 hours of incubation. Also, cell growth reduction was seen at high dose concentrations (150 and 200 µg/ml), as evident by cell count once treated with Kola nut extract. The total number of apoptotic cells increased from 5.8% of the control group to 27.4% at 250 µg/ml concentration. Moreover, Kola nut extracts' effects on K562 cells increased gradually in a dose and time-dependent manner. It was observed that Kola nut extracts could arrest the cell cycle in the G2/M phase as an increase in the number of cells by 29.8% and 14.6 % were observed from 9.8% and 5.2% after 24 and 48 hours of incubation, respectively. This increase was detected in a dose and time-dependent manner. Kola nut extracts can be used as a novel anti-cancer agent in Leukemia treatment as it has shown significant therapeutic potential and therefore provides new insights in understanding the mechanisms of its action. Keywords: Kola nut extracts, Leukemia, K562 cell line, Apoptosis, Cancer.

Real-time in situ monitoring of Lon and Caspase-3 for assessing the state of cardiomyocytes under hypoxic conditions via a novel Au-Se fluorescent nanoprobe

Myocardial dysfunction caused by cardiomyocyte apoptosis under ischemic and hypoxic conditions is the pathological basis of most cardiovascular diseases. Current diagnosis of myocardial dysfunction still focuses on the symptomatic stage, usually after the occurrence of the irreversible remodelling and functional impairment. Thus, early stage identification of the apoptotic cardiomyocytes induced by hypoxia is highly significant for preventing the onset and delaying the progression of myocardial dysfunction. Herein, a novel Au-Se nanoprobe with strong anti-interference capability was developed for simultaneous real-time in situ monitoring the expression of Lon protease (Lon) and Caspase-3 with high-fidelity in living cardiomyocytes. As Lon upregulation plays a major role in the initiation of hypoxia-induced apoptosis and Caspase-3 is a marker protein for apoptosis, the nanoprobe has been successfully applied for imaging the activation of Lon-Caspase-3 apoptotic signalling pathway and assessing the state of cardiomyocytes under hypoxic conditions. Furthermore, combining with mitochondrial H₂O₂ probe-MitoPY1, the nanoprobe was also used to confirm the synergistic effect of Lon and ROS on hypoxia-induced apoptosis of cardiomyocytes and evaluate the function of ROS scavenger on attenuating such apoptosis. This work proposed a promising strategy for early diagnosis, prevention and treatment of hypoxic-ischemic myocardial dysfunction.

A novel apoptosis probe, cyclic ApoPep-1, for in vivo imaging with multimodal applications in chronic inflammatory arthritis

Apoptosis plays an essential role in the pathophysiologic processes of rheumatoid arthritis. A molecular probe that allows spatiotemporal observation of apoptosis in vitro, in vivo, and ex vivo concomitantly would be useful to monitoring or predicting pathophysiologic stages. In this study we investigated whether cyclic apoptosis-targeting peptide-1 (_CApoPep-1) can be used as an apoptosis imaging probe in inflammatory arthritis. We tested the utility of _CApoPep-1 for detecting apoptotic immune cells in vitro and ex vivo using flow cytometry and immunofluorescence. The feasibility of visualizing and quantifying apoptosis using this probe was evaluated in a murine collagen-induced arthritis (CIA) model, especially after treatment. _CApoPep-1 peptide may successfully replace Annexin V for in vitro and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay for ex vivo in the measurement of apoptotic cells, thus function as a sensitive probe enough to be used clinically. In vivo imaging in CIA mice revealed that _CApoPep-1 had 42.9 times higher fluorescence intensity than Annexin V for apoptosis quantification. Furthermore, it may be used as an imaging probe for early detection of apoptotic response in situ after treatment. The _CApoPep-1 signal was mostly co-localized with the TUNEL signal (69.6% of TUNEL⁺ cells) in defined cell populations in joint tissues of CIA mice. These results demonstrate that _CApoPep-1 is sufficiently sensitive to be used as an apoptosis imaging probe for multipurpose applications which could detect the same target across in vitro, in vivo, to ex vivo in inflammatory arthritis.

Improved non-invasive positron emission tomographic imaging of chemotherapy-induced tumor cell death using Zirconium-89-labeled APOMAB®

Purpose

The chimeric monoclonal antibody (mAb) chDAB4 (APOMAB®) targets the Lupus associated (La)/Sjögren Syndrome-B (SSB) antigen, which is over-expressed in tumors but only becomes available for antibody binding in dead tumor cells. Hence, chDAB4 may be used as a novel theranostic tool to distinguish between responders and nonresponders early after chemotherapy. Here, we aimed to ascertain which positron emitter, Zirconium-89 ([⁸⁹Zr]Zr^IV) or Iodine-124 ([¹²⁴I]I), was best suited to label chDAB4 for post-chemotherapy PET imaging of tumor-bearing mice and to determine which of two different bifunctional chelators provided optimal tumor imaging by PET using [⁸⁹Zr]Zr^IV-labeled chDAB4.

Methods

C57BL/6 J mice bearing subcutaneous syngeneic tumors of EL4 lymphoma were either untreated or given chemotherapy, then administered radiolabeled chDAB4 after 24 h with its biodistribution examined using PET and organ assay. We compared chDAB4 radiolabeled with [⁸⁹Zr] Zr^IV or [¹²⁴I] I, or [⁸⁹Zr]Zr-chDAB4 using either DFO-NCS or DFOSq as a chelator.

Results

After chemotherapy, [⁸⁹Zr]Zr-chDAB4 showed higher and prolonged mean (± SD) tumor uptake of 29.5 ± 5.9 compared to 7.8 ± 1.2 for [¹²⁴I] I -chDAB4. In contrast, antibody uptake in healthy tissues was not affected. Compared to DFO-NCS, DFOSq did not result in significant differences in tumor uptake of [⁸⁹Zr]Zr-chDAB4 but did alter the tumor:liver ratio in treated mice 3 days after injection in favour of DFOSq (8.0 ± 1.1) compared to DFO-NCS (4.2 ± 0.7).

Conclusion

ImmunoPET using chDAB4 radiolabeled with residualizing [⁸⁹Zr] Zr^IV rather than [¹²⁴I] I optimized post-chemotherapy tumor uptake. Further, PET imaging characteristics were improved by DFOSq rather than DFO-NCS. Therefore, the radionuclide/chelator combination of [⁸⁹Zr] Zr^IV and DFOSq is preferred for the imminent clinical evaluation of chDAB4 as a selective tumor cell death radioligand.

Supplementary Information

Supplementary information accompanies this paper at 10.1186/s41181-020-00109-6.

Predictive value of oxidative stress biomarkers in drug‑free patients with schizophrenia and schizo-affective disorder

Several studies have suggested that oxidative stress may represent one of the primary etiological mechanisms of schizophrenia (SZ) and schizoaffective disorder (SAD) which can be targeted by therapeutic intervention. The present study was conducted over a period of 24 months, between June 2016 and June 2018. All enrolled subjects were Tunisian, forty five drug‑free male patients with SZ (mean age: 37.6 years), twenty one drug‑free male patients with SAD (mean age: 28.8 years) and hundred and one age and gender matched controls (mean age: 34.2 years) were enrolled in the study. Plasma reduced glutathione (GSH) and Total thiols levels were significantly decreased in patients compared to controls (respectively p<0.001; p=0.050). In addition, malondialdehyde (MDA), advanced oxidation protein products (AOPP) and protein carbonyls (PC) concentrations and glutathione peroxidase (GSH-Px) activity were significantly increased in patients compared to controls (p<0.001; p<0.001; p<0.001 and p=0.003 respectively). The binary logistic regression analysis revealed that MDA, AOPP, PC and GSH-Px could be considered as independent risk factors for SZ and SAD. When using ROC analysis, a remarkable increase in the area under the curve (AUC) with higher sensitivity (Se) and specificity (Sp) for MDA, AOPP, PC and GSH-Px combined markers was observed. The present study indicated that the identification of the predictive value of this four-selected biomarkers related to oxidative stress in drug free patients should lead to a better identification of the etiological mechanism of SZ or SAD.

An ESIPT-based ratiometric fluorescent probe for the discrimination of live and dead cells

Cell death can destroy homeostasis and is a hallmark of many pathological conditions. Discrimination of live and dead cells is a crucial task for the biological, medical and pharmaceutical studies. Herein, we constructed an ESIPT-based fluorescent probe (BTE) on the basis of the different esterase activity in live and dead cells. Under excitation, the probe BTE showed the blue emission peaked at 465 nm, while it mainly displayed green emission peaked at 543 nm after it was hydrolyzed by esterase. Imaging of the cells treated by H₂O₂ and ultraviolet (UV) radiation demonstrated that the probe BTE is effective in the detection of the health of cells, could help us to better understand cell death and its effects in a range of diseases and treatments.

BPRDP056, a novel small molecule drug conjugate specifically targeting phosphatidylserine for cancer therapy

Zinc(II)-dipicolylamine (Zn-DPA) has been shown to specifically identify and bind to phosphatidylserine (PS), which exists in bulk in the tumor microenvironment. BPRDP056, a Zn-DPA-SN38 conjugate was designed to provide PS-targeted drug delivery of a cytotoxic SN38 to the tumor microenvironment, thereby allowing a lower dosage of SN38 that induces apoptosis in cancer cells. Micro-Western assay showed that BPRDP056 exhibited apoptotic signal levels similar to those of CPT-11 in the treated tumors growing in mice. Pharmacokinetic study showed that BPRDP056 has excellent systemic stability in circulation in mice and rats. BPRDP056 is accumulated in tumors and thus increases the cytotoxic effects of SN38. The in vivo antitumor activities of BPRDP056 have been shown to be significant in subcutaneous pancreas, prostate, colon, liver, breast, and glioblastoma tumors, included an orthotopic pancreatic tumor, in mice. BPRDP056 shrunk tumors at a lower (~20% only) dosing intensity of SN38 compared to that of SN38 conjugated in CPT-11 in all tumor models tested. A wide spectrum of antitumor activities is expected to treat all cancer types of PS-rich tumor microenvironments. BPRDP056 is a first-in-class small molecule drug conjugate for cancer therapy.

Design and Evaluation of Rhein-Based MRI Contrast Agents for Visualization of Tumor Necrosis Induced by Combretastatin A-4 Disodium Phosphate

PURPOSE

Visualization of tumor necrosis can determine tumor response to therapy. Our previous study showed that the rhein-based magnetic resonance imaging (MRI) contrast agent with alkane linker (GdL₂) could clearly image tumor necrosis. However, its water solubility and cell safety needed to be improved. Herein, three rhein-based MRI agents with ether or lysine linkers were designed.

PROCEDURES

Three rhein-based MRI agents were synthesized with a tetracarbon ether (GdP1), a hexacarbon ether (GdP2), and a lysine (GdP3) linker, respectively. Their octanol-water partition coefficients (log P) and cytotoxicity were determined. Necrosis avidity of the leading agent was explored on HepG2 cells and ischemia reperfusion-induced liver necrosis (IRLN) rats by MRI. The effect of visualization of tumor necrosis was tested on nude mice with W256 tumor treated by combretastatin-A4 phosphate (CA4P). DNA binding assays were applied to evaluate the possible necrosis-avidity mechanism of the leading agent.

RESULTS

The log P of three agents (- 1.66 ± 0.09, - 1.74 ± 0.01, - 1.95 ± 0.01) decreased when compared with GdL₂, indicating higher water solubility. GdP1 not only presented lower cytotoxicity and good necrotic affinity in vitro and in vivo, but also can be fast excreted by renal. According to MRI results of tumor, distinct visualization of tumor necrosis can be discernible from 3 to 4.5 h post-injection of GdP1. In DNA-binding assays, the fluorescence quenching constant K_SV (1.00 × 10⁴ M^-1) and the ultraviolet binding constant K_b (1.11 × 10⁴ M^-1) suggested that GdP1 may bind to DNA through intercalation.

CONCLUSION

GdP1 may serve as a potential candidate for early evaluation of tumor response to CA4P treatment.

Strategies for altering lipid self-assembly to trigger liposome cargo release

While liposomes have proven to be effective drug delivery nanocarriers, their therapeutic attributes could be improved through the development of clinically viable triggered release strategies in which encapsulated drug contents could be selectively released at the sites of diseased cells. As such, a significant amount of research has been reported involving the development of stimuli-responsive liposomes and a broad range of strategies have been explored for driving content release. These have included the introduction of trigger groups at either the lipid headgroup or within the acyl chains that alter lipid self-assembly properties of known lipids as well as the rational design of lipid analogs programed to undergo conformational changes induced by events such as binding interactions. This review article describes advances in the design of stimuli-responsive liposome strategies with an eye towards emerging trends in the field.

The evolving roles of radiolabeled quinones as small molecular probes in necrotic imaging

Necrosis plays vital roles in living organisms which is related closely with various diseases. Non-invasively necrotic imaging can be of great values in clinical decision-making, evaluation of individualized treatment responses, and prediction of patient prognosis. This narrative review will demonstrate how the evolution of quinones for necrotic imaging has been promoted by searching for their active centers. In this review, we summarized the recent developments of various quinones with the continuous simplified π-conjugated cores in necrotic imaging and speculated their possible molecular mechanisms might be attributed to their intercalations with exposed DNA in necrotic tissues. We discussed their clinical challenges of necrotic imaging with quinones and their future translation studies deserved to be explored in personalized patient treatment.

Protease-responsive mass barcoded nanotranslators for simultaneously quantifying the intracellular activity of cascaded caspases in apoptosis pathways

Quantitatively delineating the activation network of multiple proteases that participate in cellular processes is highly essential for understanding the physiological and pathological states of cells. In this study, protease-responsive mass barcoded nanotranslators (PRMNTs) were engineered for revealing the activity of cascaded caspases in apoptosis in a multiplex and quantitative manner. In the PRMNTs, a series of mass tag-decorated gold nanoparticles (AuNPs) were tethered onto magnetic Fe₃O₄ nanospheres via a linker containing the substrate peptide of the target protease to form a "one-to-many" core-satellite structure. This nanostructure was internalized into the cells, underwent an enzymatic reaction within the cells, and allowed post-reaction mass spectrometry (MS) interrogation after magnetic separation from the cells. In the presence of intracellular caspases, enzymatic cleavage of the linker could be translated to the decreased ion signals of the mass tags on the remaining AuNPs in the PRMNTs by MS decoding. Benefiting from the multiplexing capability of MS, the intracellular activity of caspase-3, -8 and -9 that orchestrate the apoptotic process was simultaneously quantified at any given time. Kinetic analysis of caspase activity under stimulation of diverse anticancer drugs revealed that programmed cell death followed individual apoptosis pathways, differing in the activation degree and sequence of the caspase cascade. This work represents a modality that interfaces nanotechnology with MS for quantitatively probing the intracellular activity of multiple proteases, which opens up new avenues for revealing the apoptosis mechanism and developing innovative drugs.

Discovery of necrosis avidity of rhein and its applications in necrosis imaging

Necrosis-avid agents possess exploitable theragnostic utilities including evaluation of tissue viability, monitoring of therapeutic efficacy as well as diagnosis and treatment of necrosis-related disorders. Rhein (4,5-dihydroxyl-2-carboxylic-9,10-dihydrodiketoanthracene), a naturally occurring monomeric anthraquinone compound extensively found in medicinal herbs, was recently demonstrated to have a newly discovered necrosis-avid trait and to show promising application in necrosis imaging. In this overview, we present the discovering process of rhein as a new necrosis-avid agent as well as its potential imaging applications in visualisation of myocardial necrosis and early evaluation of tumour response to therapy. Moreover, the molecular mechanism exploration of necrosis avidity behind rhein are also presented. The discovery of necrosis avidity with rhein and the development of rhein-based molecular probes may further expand the scope of necrosis-avid compounds and highlight the potential utility of necrosis-avid molecular probes in necrosis imaging.

Imaging Cell Death: Focus on Early Evaluation of Tumor Response to Therapy

Cell death plays a prominent role in the treatment of cancer, because most anticancer therapies act by the induction of cell death including apoptosis, necrosis, and other pathways of cell death. Imaging cell death helps to identify treatment responders from nonresponders and thus enables patient-tailored therapy, which will increase the likelihood of treatment response and ultimately lead to improved patient survival. By taking advantage of molecular probes that specifically target the biomarkers/biochemical processes of cell death, cell death imaging can be successfully achieved. In recent years, with the increased understanding of the molecular mechanism of cell death, a variety of well-defined biomarkers/biochemical processes of cell death have been identified. By targeting these established cell death biomarkers/biochemical processes, a set of molecular imaging probes have been developed and evaluated for early monitoring treatment response in tumors. In this review, we mainly present the recent advances in identifying useful biomarkers/biochemical processes for both apoptosis and necrosis imaging and in developing molecular imaging probes targeting these biomarkers/biochemical processes, with a focus on their application in early evaluation of tumor response to therapy.

Early prediction of tumor response after radiotherapy in combination with cetuximab in nasopharyngeal carcinoma using 99m Tc-duramycin imaging

PURPOSE

^99mTc-duramycin imaging enables specific visualization of cell death qualitatively and quantitatively. This study aimed to investigate the potential of ^99mTc-duramycin imaging in the early prediction of the curative effect of radiotherapy in combination with or without cetuximab in a nasopharyngeal carcinoma (NPC) model.

METHODS

Male BALB/c mice bearing NPC xenografts were randomized into four groups (six mice each group). Group 1 received radiotherapy (RT, 15 Gy/mouse) in combination with cetuximab (CTX, 2 mg/mouse), group 2 received RT (15 Gy/mouse), group 3 was treated using CTX (2 mg/mouse), and group 4, the control group, was treated using a vehicle. ^99mTc-duramycin imaging was performed before treatment and 24 h after treatment to evaluate tumor response. Tumor uptake of ^99mTc-duramycin was validated ex vivo using γ-counting. Treatment response was further validated by cleaved caspase-3 (CC3) and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL). Another four groups were treated parallelly under the same conditions to observe treatment response by tumor volume changes.

RESULTS

After 24 h treatment, ^99mTc-duramycin uptake in the NPC tumor models were significantly higher in group 1 than in group 2 (P < 0.05), group 3 (P < 0.05), or group 4 (P < 0.05); the uptake also increased notably in comparison with baseline values (P < 0.05). Compared with group 4, group 2 and group 3 both showed significant ^99mTc-duramycin uptake in the tumors (P < 0.05). Although the ^99mTc-duramycin uptake of group 2 was moderately higher than group 3, there were no significant differences between these two groups (P >0.05). There was a strong positive correlation between tumor ^99mTc-duramycin uptake and CC3 (r = 0.893, p < 0.0001) and TUNEL (r = 0.918, P < 0.0001). Tumor volume decreased remarkably in the RT in combination with CTX group on day 5, in the RT alone group on day 7, and was inhibited on day 8 in the CTX alone group, whereas the tumors grew continuously in the control group.

CONCLUSIONS

We demonstrated that RT in combination with CTX treatment significantly improved disease control in a NPC xenograft model compared with monotherapy with either. ^99mTc-duramycin imaging might be able to reliably identify response to RT in combination with CTX as early as 24 h after therapy initiation in NPC xenograft models. This might help to isolate non-responding patients in a timely manner and avoid unnecessary side effects in the clinic in the future.

A Model In Vitro Study Using Hypericin: Tumor-Versus Necrosis-Targeting Property and Possible Mechanisms

Hypericin (Hyp) had been explored as a tumor-seeking agent for years; however, more recent studies showed its necrosis-avidity rather than cancer-seeking property. To further look into this discrepancy, we conducted an in vitro study on Hyp retention in vital and dead cancerous HepG2 and normal LO2 cell lines by measuring the fluorescence intensity and concentration of Hyp in cells. To question the DNA binding theory for its necrosis-avidity, the subcellular distribution of Hyp was also investigated to explore the possible mechanisms of the necrosis avidity. The fluorescence intensity and concentration are significantly higher in dead cells than those in vital cells, and this difference did not differ between HepG2 and LO2 cell lines. Hyp was taken up in vital cells in the early phase and excreted within hours, whereas it was retained in dead cells for more than two days. Confocal microscopy showed that Hyp selectively accumulated in lysosomes rather than cell membrane or nuclei. Hyp showed a necrosis-avid property rather than cancer-targetability. The long-lasting retention of Hyp in dead cells may be associated with halted energy metabolism and/or binding with certain degraded cellular substrates. Necrosis-avidity of Hyp was confirmed, which may be associated with halted energy metabolism in dead LO2 or HepG2 cells.

[18F]ML-10 PET imaging fails to assess early response to neoadjuvant chemotherapy in a preclinical model of triple negative breast cancer

PURPOSE

Pathological complete response to the neoadjuvant therapy (NAT) for triple negative breast cancer (TNBC) is predictive of prolonged patient survival. Methods for early evaluation of NAT efficiency are still needed, in order to rapidly adjust the therapeutic strategy in case of initial non-response. One option for this is molecular imaging of apoptosis induced by chemotherapy. Therefore, we investigated the capacity of [18F]ML-10 PET imaging, an apoptosis radiotracer, to detect tumor cell apoptosis and early predict the therapeutic response of human TNBC.

RESULTS

Initially, the induction of apoptosis by different therapies was quantified. We confirmed, in vitro, that paclitaxel or epirubicin, the fundamental cytotoxic drugs for breast cancer, induce apoptosis in TNBC cell lines. Exposure of TNBC models MDA-MB-231 and MDA-MB-468 to these drugs induced a significant increase (p < 0.01) of the apoptotic hallmarks: DNA fragmentation, membrane phospholipid scrambling, and PARP activation. Secondarily, apoptotic fraction was compared to the intracellular accumulation of the radiotracer. [18F]ML-10 accumulated in the apoptotic cells after 72 h of treatment by paclitaxel in vitro; this accumulation positively correlated with the apoptotic fraction. In vivo, [18F]ML-10 was rapidly cleared from the nontarget organs and mainly eliminated by the kidneys. Comparison of the in vivo [18F]FDG, [18F]FMISO, and [18F]ML-10 uptakes revealed that the tumor accumulation of [18F]ML-10 was directly related to the tumor hypoxia level. Finally, after the in vivo treatment of TNBC murine xenografts by paclitaxel, apoptosis was well induced, as demonstrated by the cleaved caspase-3 levels; however, no significant increase of [18F]ML-10 accumulation in the tumors was observed, either on day 3 or day 6 after the end of the treatment.

CONCLUSIONS

These results highlighted that PET imaging using [18F]ML-10 allows the visualization of apoptotic cells in TNBC models. Nevertheless, the increase of the chemotherapy-induced apoptotic response when using paclitaxel could not be assessed using this radiotracer in our mouse model.

One-Pot Radiosynthesis and Biological Evaluation of a Caspase-3 Selective 5-[123,125I]iodo-1,2,3-triazole derived Isatin SPECT Tracer

Induction of apoptosis is often necessary for successful cancer therapy, and the non-invasive monitoring of apoptosis post-therapy could assist in clinical decision making. Isatins are a class of compounds that target activated caspase-3 during apoptosis. Here we report the synthesis of the 5-iodo-1,2,3-triazole (FITI) analog of the PET tracer [18F]ICMT11 as a candidate tracer for imaging of apoptosis with SPECT, as well as PET. Labelling with radioiodine (123,125I) was achieved in 55 ± 12% radiochemical yield through a chelator-accelerated one-pot cycloaddition reaction mediated by copper(I) catalysis. The caspase-3 binding affinity and selectivity of FITI compares favourably to that of [18F]ICMT11 (Ki = 6.1 ± 0.9 nM and 12.4 ± 4.7 nM, respectively). In biodistribution studies, etoposide-induced cell death in a SW1222 xenograft model resulted in a 2-fold increase in tumour uptake of the tracer. However, the tumour uptake was too low to allow in vivo imaging of apoptosis with SPECT.

Targeting phosphatidylethanolamine and phosphatidylserine for imaging apoptosis in cancer

INTRODUCTION

Both phosphatidylethanolamine (PE) and phosphatidylserine (PS) can be externalized to the outer cell membrane in apoptosis. Thus the objective was to determine whether PE-targeting ¹⁸F-duramycin and PS-targeting ¹⁸F-Zn-DPA could be used for imaging apoptosis.

METHODS

Duramycin and Zn-DPA were labeled with either ¹⁸F-Al or ¹⁸F-SFB. U937 cells were incubated with four different concentrations of camptothecin (CPT). For assessing the effect of incubation time on uptake, 37 MBq of radiotracer was added to cells incubated for 15, 30, 60, and 120 min at 37 °C. For blocking experiments, 150 μg duramycin and 40 μg Zn-DPA were added to cells for 15 min prior to the addition of either duramycin or Zn-DPA labeled with ¹⁸F. Apoptosis was measured by flow cytometry using an annexin-V/PI kit. Cells were co-stained with Hoechst, Cy5-duramycin, and PSVue480 (FITC-Zn-DPA) to localize fluorescent dye uptake in cells.

RESULTS

Apoptosis in cells increased proportionally with CTP as confirmed by both flow cytometry and fluorescent staining. Both FITC-Zn-DPA and FITC-duramycin localized mainly on the cell membrane during early apoptosis and then translocated to the inside during late apoptosis. Uptake of FITC-duramycin, however, was higher than that of FITC-Zn-DPA. Cellular uptake of four different radiotracers was also proportional to the degree of apoptosis, increasing slightly over time and reaching a plateau at about 1 h. The blocking experiments demonstrated that uptake in all the control groups was predominantly non-specific, whereas the specific uptake in all the treated groups was at least 50% for both ¹⁸F labeled duramycin and Zn-DPA.

CONCLUSION

Both PE-targeting ¹⁸F-duramycin and PS-targeting ¹⁸F-Zn-DPA could be considered as potential radiotracers for imaging cellular apoptosis. Advances in knowledge and implications for patient care: Cellular data support the further development of radiotracers targeting either PE or PS for imaging apoptosis, which can associate with clinical outcome for cancer patients.

Rational design of caspase-responsive smart molecular probe for positron emission tomography imaging of drug-induced apoptosis

Purpose: Positron emission tomography (PET) imaging of apoptosis is very important for early evaluation of tumor therapeutic efficacy. A stimuli-responsive probe based on the peptide sequence Asp-Glu-Val-Asp (DEVD), [¹⁸F]DEVD-Cys(StBu)-PPG(CBT)-AmBF₃ ([¹⁸F]1), for PET imaging of tumor apoptosis was designed and prepared. This study aimed to develop a novel smart probe using a convenient radiosynthesis method and to fully examine the sensitivity and specificity of the probe response to the tumor treatment.

Methods: The radiolabelling precursor DEVD-Cys(StBu)-PPG(CBT)-AmBF₃ (1) was synthesized through multistep reactions. The reduction together with caspase-controlled macrocyclization and self-assembly of 1 was characterized and validated in vitro. After [¹⁸F]fluorination in the buffer (pH= 2.5), the radiolabelling yield (RLY), radiochemical purity (RCP) and stability of the probe [¹⁸F]1 in PBS and mouse serum were investigated by radio-HPLC. The sensitivity and specificity of [¹⁸F]1 for detecting the drug-induced apoptosis was fully evaluated in vitro and in vivo. The effect of cold precursor 1 on the cell uptake and tumor imaging of [¹⁸F]1 was also assessed. The level of activated caspase-3 in Hela cells and tumors with or without apoptosis induction was analyzed and compared by western blotting and histological staining.

Results: The whole radiosynthesis process of [¹⁸F]1 was around 25 min with RLY of 50%, RCP of over 99% and specific activity of 1.45 ± 0.4 Ci/µmol. The probe was very stable in both PBS and mouse serum within 4 h. It can be activated by caspase-3 and then undergo an intermolecular cyclization to form nanosized particles. The retained [¹⁸F]1 in DOX-treated HeLa cells was 2.2 folds of that in untreated cells. Within 1 h microPET imaging of the untreated Hela-bearing mice, the injection of [¹⁸F]1 resulted in the increase of the uptake ratio of tumor to muscle (T/M) only from 1.74 to 2.18, while in the DOX-treated Hela-bearing mice T/M increased from 1.88 to 10.52 and the co-injection of [¹⁸F]1 and 1 even led to the increase of T/M from 3.08 to 14.81.

Conclusions: A caspase-responsive smart PET probe [¹⁸F]1 was designed and prepared in a kit-like manner. Co-injection of [¹⁸F]1 and 1 generated remarkably enhanced tumor uptake and signal-to-noise ratio in the tumor-bearing mice with drug-induced apoptosis, which correlated well with the expression level of activated caspase-3. This early readout of treatment response ensured that the probe [¹⁸F]1 could serve as a promising PET imaging probe for timely and noninvasive evaluation of tumor therapy.

Rhein-based necrosis-avid MRI contrast agents for early evaluation of tumor response to microwave ablation therapy

PURPOSE

Early evaluation of tumor response to thermal ablation therapy can help identify untreated tumor cells and then perform repeated treatment as soon as possible. The purpose of this work was to explore the potential of rhein-based necrosis-avid contrast agents (NACAs) for early evaluation of tumor response to microwave ablation (MWA).

METHODS

3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay was performed to test the cytotoxicity of rhein-based NACAs against HepG2 cells. Rat models of liver MWA were used for investigating the effectiveness of rhein-based NACAs in imaging the MWA lesion, the optimal time period for post-MWA MRI examination, and the metabolic behaviors of ⁶⁸ Ga-labeled rhein-based NACAs. Rat models of orthotopic liver W256 tumor MWA were used for investigating the time window of rhein-based NACAs for imaging the MWA lesion, the effectiveness of these NACAs in distinguishing the residual tumor and the MWA lesion, and their feasibility in early evaluating the tumor response to MWA.

RESULTS

Gadolinium 2,2',2''-(10-(2-((4-(4,5-Dihydroxy-9,10-dioxo-9,10-dihydroanthracene-2-carboxamido)butyl)amino)-2-oxoethyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl)triacetic acid (GdL₂ ) showed low cytotoxicity and high quality in imaging the MWA region. The optimal time period for post-MWA MRI examination using GdL₂ was 2 to 24 h after the treatment. During 2.5 to 3.5 h postinjection, GdL₂ can better visualize the MWA lesion in comparison with gadolinium 2-[4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododec-1-yl]acetic acid (Gd-DOTA), and the residual tumor would not be enhanced. The tumor response to MWA as evaluated by using GdL₂ -enhanced MRI was consistent with histological examination.

CONCLUSION

GdL₂ appears to be a promising NACA for the tumor response assessment after thermal ablation therapies.

Synthesis and Evaluation of Diindole-Based MRI Contrast Agent for In Vivo Visualization of Necrosis

PURPOSE

Noninvasive imaging of cell necrosis can provide an early evaluation of tumor response to treatments. Here, we aimed to design and synthesize a novel diindole-based magnetic resonance imaging (MRI) contrast agent (Gd-bis-DOTA-diindolylmethane, Gd-DIM) for assessment of tumor response to therapy at an early stage.

PROCEDURES

The oil-water partition coefficient (Log P) and relaxivity of Gd-DIM were determined in vitro. Then, its necrosis avidity was examined in necrotic cells in vitro and in rat models with microwave ablation-induced muscle necrosis (MAMN) and ischemia reperfusion-induced liver necrosis (IRLN) by MRI. Visualization of tumor necrosis induced by combretastatin A-4 disodium phosphate (CA4P) was evaluated in rats bearing W256 orthotopic liver tumor by MRI. Finally, DNA binding assay was performed to explore the possible necrosis-avidity mechanism of Gd-DIM.

RESULTS

The Log P value and T1 relaxivity of Gd-DIM is - 2.15 ± 0.01 and 6.61 mM^-1 s^-1, respectively. Gd-DIM showed predominant necrosis avidity in vitro and in vivo. Clear visualization of the tumor necrosis induced by CA4P was achieved at 60 min after administration of Gd-DIM. DNA binding study indicated that the necrosis-avidity mechanism of Gd-DIM may be due to its binding to exposed DNA in necrotic cells.

CONCLUSION

Gd-DIM may serve as a promising necrosis-avid MRI contrast agent for early assessment of tumor response to therapy.

The cGMP Pathway and Inherited Photoreceptor Degeneration: Targets, Compounds, and Biomarkers

Photoreceptor physiology and pathophysiology is intricately linked to guanosine-3’,5’-cyclic monophosphate (cGMP)-signaling. Here, we discuss the importance of cGMP-signaling for the pathogenesis of hereditary retinal degeneration. Excessive accumulation of cGMP in photoreceptors is a common denominator in cell death caused by a variety of different gene mutations. The cGMP-dependent cell death pathway may be targeted for the treatment of inherited photoreceptor degeneration, using specifically designed and formulated inhibitory cGMP analogues. Moreover, cGMP-signaling and its down-stream targets may be exploited for the development of novel biomarkers that could facilitate monitoring of disease progression and reveal the response to treatment in future clinical trials. We then briefly present the importance of appropriate formulations for delivery to the retina, both for drug and biomarker applications. Finally, the review touches on important aspects of future clinical translation, highlighting the need for interdisciplinary cooperation of researchers from a diverse range of fields.

Updated developments on molecular imaging and therapeutic strategies directed against necrosis

Cell death plays important roles in living organisms and is a hallmark of numerous disorders such as cardiovascular diseases, sepsis and acute pancreatitis. Moreover, cell death also plays a pivotal role in the treatment of certain diseases, for example, cancer. Noninvasive visualization of cell death contributes to gained insight into diseases, development of individualized treatment plans, evaluation of treatment responses, and prediction of patient prognosis. On the other hand, cell death can also be targeted for the treatment of diseases. Although there are many ways for a cell to die, only apoptosis and necrosis have been extensively studied in terms of cell death related theranostics. This review mainly focuses on molecular imaging and therapeutic strategies directed against necrosis. Necrosis shares common morphological characteristics including the rupture of cell membrane integrity and release of cellular contents, which provide potential biomarkers for visualization of necrosis and necrosis targeted therapy. In the present review, we summarize the updated joint efforts to develop molecular imaging probes and therapeutic strategies targeting the biomarkers exposed by necrotic cells. Moreover, we also discuss the challenges in developing necrosis imaging probes and propose several biomarkers of necrosis that deserve to be explored in future imaging and therapy research.

Evaluation of Necrosis Avidity and Potential for Rapid Imaging of Necrotic Myocardium of Radioiodinated Hypocrellins

PURPOSE

Rapid noninvasive delineation of necrotic myocardium in ischemic regions is very critical for risk stratification and clinical decision-making but still challenging. This study aimed to evaluate the necrosis avidity of radioiodinated hypocrellins and its potential for rapidly imaging necrotic myocardium.

PROCEDURES

The aggregation constants of four natural hypocrellins were analyzed by UV/vis spectroscopy. Then, they were radiolabeled with iodine-131 by iodogen oxidation method. Necrosis avidity of iodine-131-labeled hypocrellins was evaluated in rat models with reperfused liver infarction and muscular necrosis by gamma counting, autoradiography, and histopathology. Their pharmacokinetic properties were examined in normal rats. The potential of iodine-131-labeled hypomycin A ([¹³¹I]HD) for early imaging of necrotic myocardium was explored in rat models with reperfused myocardial infarction. Finally, the possible mechanism of necrosis avidity was investigated by in vitro DNA binding and in vivo blocking experiments.

RESULTS

The aggregation constants of four hypocrellins were all much smaller than that of hypericin, a most studied necrosis avid agent. The radiochemical purities of the four radiotracers after purification were all greater than 95 %, and more than 90 % of tracers remained intact after incubation in rat serum for 24 h. Among the four tracers, [¹³¹I]HD exhibited the highest necrotic to viable tissue uptake ratio and the fastest blood clearance. The necrotic myocardium could be clearly visualized 4 h after injection of [¹³¹I]HD by single-photon emission computed tomography/X-ray computed tomography (SPECT/CT). DNA binding studies suggested that HD could bind to DNA through intercalation. Blocking studies demonstrated that uptake of [¹³¹I]HD in necrotic muscle could be significantly blocked by excess unlabeled HD and ethidium bromide with 67 and 60 % decline at 6 h after coinjection, respectively.

CONCLUSIONS

[¹³¹I]HD can be used to rapidly visualize necrotic myocardium. The necrosis avidity mechanism of [¹³¹I]HD may be attributed to its binding to the exposed DNA in necrotic tissues.

Target exploration of rhein as a small-molecule necrosis avid agent by post-treatment click modification

Post-labeling of compound 3 indicated that binding to exposed DNA may be an important mechanism of targeting of rhein compounds to necrotic cells.

Lipid Switches: Stimuli-Responsive Liposomes through Conformational Isomerism Driven by Molecular Recognition

Advancements in the field of liposomal drug carriers have culminated in greatly improved delivery properties. An important aspect of this work entails development of designer liposomes for release of contents triggered by environmental changes. The majority of these systems are driven by chemical reactions in the presence of different stimuli. However, a promising new paradigm instead focuses on molecular recognition events as the impetus for content release. In certain cases, these platforms exploit synthetic lipid switches designed to undergo conformational changes upon binding to target ions or molecules that perturb membrane assembly, thereby triggering cargo release. Examples of this approach reported thus far showcase how rational design of lipid switches can result in dramatic changes in lipid assembly properties. These strategies show great promise for opening up new pathophysiological stimuli that can be harnessed for programmed content release in drug delivery applications.

pH-Sensitive micelles with mitochondria-targeted and aggregation-induced emission characterization: synthesis, cytotoxicity and biological applications

Subcellular organelle-specific reagents for simultaneous tumor targeting, imaging, and treatment are of enormous interest in cancer therapy. Herein, we present a mitochondria targeting micelle (PEG-AIE-TPP) by conjugating a triphenylphosphonium (TPP) with a fluorogen which can undergo aggregation-induced emission (AIE). At first, the in vitro and in vivo properties of the PEG-AIE-TPP micelle were characterized in detail. It was found that the micelle was reasonably stable at physiological pH and highly sensitive to mildly acidic pH stimuli. Importantly, this micelle could selectively localize and accumulate in the mitochondria, thus generating an aggregation-induced emission (AIE) effect as confirmed by the green fluorescence. Additionally, the micelle exhibited selective cytotoxicity to cancer cells and negligible toxicity to normal cells in vitro. The in vivo imaging and ex vivo imaging results showed that the accumulation tendency of the micelle at the tumor region was obvious. We also further proved the biocompatible, tumor targeting ability and antitumor activity of the PEG-AIE-TPP micelle in MCF-7 tumor-bearing mice. Accordingly, this mitochondria-targeted therapeutic micelle with good stability, biocompatibility, and tumor-targeting and antitumor activity provides a potentially unique tumor-targeted system for cancer therapy.

Investigation of potent anticarcinogenic activity of 1, 3-diarylpyrazole acrylamide derivatives in vitro

OBJECTIVES

Pyrazole derivatives are pharmacologically powerful agents pointing at new horizons in the development of anticancer therapies. In this study, anticarcinogenic potential of a series of pyrazole-acrylamide derivatives has been investigated in mesothelial, malignant mesothelioma and lung cancer cell lines.

METHODS

The effect of compounds on the viability of cells and the distribution of cell cycle were examined through MTS assay and PI staining, respectively. Apoptosis was evaluated via caspase-3 enzymatic assay and AO/EB staining. Proteins involved in proliferation, survival and apoptosis were analysed by immunoblotting.

KEY FINDINGS

Twelve compounds of 21 (4a-4v) reduced the viability of cells but, only the subset of five (4f, 4i, 4j, 4k and 4v) induced the caspase-3 activity. Among five, only one compound (4k) significantly suppressed phosphorylation and expression of ERK1/2 and AKT proteins in 24 h. Exposing cancer cells to successive concentrations of 4k gave rise to dose- and time-dependent G2/M phase arrest and apoptosis.

CONCLUSIONS

4k has revealed its potent antiproliferative activity by decreasing viability and inhibiting proliferation and survival signals of cancer cells. Moreover, 4k has exposed cytostatic and apoptotic effect especially, on cancer cells. Therefore, it may be necessary to examine the biological actions of 4k in vivo as well.