Integrin-αvβ3 as a Therapeutic Target in Glioblastoma: Back to the Future?

Design of a Tetravalent RGD Peptide Capable of Simultaneous Binding with Multiple Integrin αvβ3 for Targeted Radionuclide Therapy

For targeted radionuclide therapy, radioligands that exhibit high and persistent tumor uptake are indispensable. We previously synthesized a 99mTc-labeled hexavalent RGD peptide (99mTc-(RGD)6) as a tumor imaging agent targeting integrin αvβ3. 99mTc-(RGD)6 showed high in vivo tumor uptake with long retention due to simultaneous binding to multiple integrin αvβ3 receptors. The purpose of this study was to apply this finding to the design of a multivalent RGD peptide labeled with 211At, a promising α-emitting radionuclide for radionuclide therapy. As a candidate compound, a tetravalent RGD peptide (H2N-(RGD)4) was synthesized and radiolabeled with 125I, a homologous element of At, for basic studies. As expected, 125I-(RGD)4 retained the capability of simultaneous binding and showed comparable in vivo tumor uptake to 99mTc-(RGD)6. Finally, 211At-(RGD)4 was synthesized with >95% radiochemical purity and exhibited an almost identical biodistribution pattern to 125I-(RGD)4. These results indicate that 211At-(RGD)4 might be a potential radioligand for integrin αvβ3-targeted radionuclide therapy.

Matrix metallopeptidase 2-responsive curcumin-loaded nanoparticles-induced signal transducer and activator of transcription 3 inhibition suppresses glioblastoma multiforme growth via enhancing nuclear factor erythroid 2-related factor 2 activity

This study investigated the inhibitory effects of matrix metallopeptidase 2 (MMP2)-responsive curcumin-loaded nanoparticles on glioblastoma multiforme (GBM), and elucidated their underlying mechanisms. The methods employed included the Cell Counting Kit-8 viability assay, colony formation assay, flow cytometry for apoptosis analysis, wound healing migration assay, quantitative real-time polymerase chain reaction, western blotting for gene expression profiling, mitochondrial function assessment, and in vivo antitumor efficacy evaluation. Curcumin significantly reduced the viability, proliferation, and migratory capacity of murine glioma cells (GL261). It also induced apoptosis, disrupted mitochondrial function, and increased reactive oxygen species levels. Notably, curcumin upregulated nuclear factor erythroid 2-related factor 2 (Nrf2) expression while inhibiting signal transducer and activator of transcription 3 (STAT3) activation. The synthesized MMP2-responsive curcumin nanoparticles (Cur-NPs) effectively suppressed tumor growth and prolonged survival in a GBM mouse model. These data suggest that curcumin inhibits STAT3 activity via an Nrf2-dependent mechanism. This study advances our understanding of the mechanism of action of curcumin and suggests potential avenues for the development of targeted therapies for GBM.

Cell membrane sialome machinery and regulation of receptor tyrosine kinases in gliomas: The functional relevance and therapeutic perspectives

Gliomas are the most common primary brain tumors characterized by high aggressive potential, poor therapeutic response, and significantly reduced overall patient survival. Despite significant progress in the diagnosis and therapy of cancer, gliomas remain a clinical challenge due to the high molecular and cellular heterogeneity, which provides for multiple mechanisms of chemoresistance and adaptive plasticity. A better understanding of cellular regulatory mechanisms of intracellular signal transduction enables the development of targeted drug therapies and clinical application. The increasing evidence confirms the role of sialoglycans in the processing of cell membrane receptors via altered dimerization, activation, and autophosphorylation, which results in changes in cellular signaling and promotes cancer progression. Hence, the modified sialylation patterns, as a hallmark of cancer, have been described as modulators of chemotherapy effectiveness and drug resistance. The receptor tyrosine kinases (RTKs)-mediated signaling in glial tumors control cell growth, survival, migration, and angiogenesis. Here, we focus on the engagement of the sialome machinery in RTKs processing in gliomas and its importance as a suitable therapeutic target. The analysis of the sialylation pattern and its impact on the activity of growth factor receptors provides valuable insights into our understanding of the molecular and cellular complexity of glial tumors. This highlights the novel treatment approaches that could improve prognosis and patients' overall survival.

Interaction of integrin αvβ3 and fibronectin under fluid shear forces: implications for tumor cell adhesion and migration

The interaction between integrin αvβ3 and fibronectin enables tumor cell adherence to endothelial layers under diverse hydrodynamic blood flow conditions, particularly in low shear stress regions. Understanding the mechanical binding characteristics between integrin αvβ3 and fibronectin under different hydrodynamic environments can provide insights into tumor cell invasion and proliferation. Here, the adhesive behavior of fibronectin-functionalized microspheres on integrin αvβ3-coated substrates under various wall fluid shear forces (0.1-0.7 dyn/cm2) was assessed using a parallel plate flow chamber system. The bond lifetimes of integrin αvβ3-fibronectin initially increased and then decreased, indicating transition from a "catch bond" to "slip bond." Upon perfusion of fibronectin-coated microspheres into flow chambers with high-density integrin αvβ3 coating, the rolling velocity of the microspheres increased with increasing shear force. Additionally, the mean stop time and stop frequency exhibited a force-dependent biphasic pattern, initially increasing and then decreasing with shear force, demonstrating a nuanced response to mechanical forces. Thus, the integrin αvβ3-fibronectin interaction displays a "catch bond" property, influencing cell distribution in varying fluid shear forces by promoting optimal adhesion in specific shear sites. These insights enhance our understanding of tumor cell adhesion and migration in hydrodynamic environments and may aid the design of integrin αvβ3-targeted therapies.

Glioblastoma Cell Migration, Invasion and Vasculogenic Mimicry Downmodulated by Novel uPAcyclin Derivatives

Despite extensive efforts to develop new treatments, the prognosis for glioblastoma multiforme (GBM) is extremely unfavorable, urging the identification of new chemotherapeutics. A previous work identified the cyclic decapeptide uPAcyclin as a potent inhibitor of GBM cell migration, matrix invasion and vascular-like structures' formation, acting through binding to αV integrins and not interfering with cell proliferation or survival. These clearcut activities prompted us to design and test novel derivatives on cultured U87-MG and U251 GBM-MG human cells. With the exception of the residues involved in peptide cyclization, residues were Ala-substituted one by one and the single peptides tested for binding affinity for the αV target integrin, the inhibition of migration, invasion and vasculogenic mimicry. The first screening highlighted peptides with a low binding affinity and low inhibitory ability (Ala4,7,9 derivatives) and peptides with affinity and inhibitory capacity higher than uPAcyclin (Ala2,5,6,8 derivatives). The integration of these results with conformational studies led to the design of the di-substituted variant uPAcyclin. Intriguingly, at least ten-fold greater anti-migratory and anti-invasive effects of the [Ala2,Ala5]uPAcyclin variant compared to uPAcyclin were found. The latter variant also exhibited a greater inhibitory potential for vascular-like structures' formation by matrix-seeded GBM cells. These studies shed light on the functional relevance of single amino acid residues in uPAcyclin and lead to the identification of therapeutically interesting new variants as promising candidates for anti-GBM therapies.

Engineering with Biomedical Sciences Changing the Horizon of Healthcare-A Review

In the dynamic realm of healthcare, the convergence of engineering and biomedical sciences has emerged as a pivotal frontier. In this review we go into specific areas of innovation, including medical imaging and diagnosis, developments in biomedical sensors, and drug delivery systems. Wearable biosensors, non-wearable biosensors, and biochips, which include gene chips, protein chips, and cell chips, are all included in the scope of the topic that pertains to biomedical sensors. Extensive research is conducted on drug delivery systems, spanning topics such as the integration of computer modeling, the optimization of drug formulations, and the design of delivery devices. Furthermore, the paper investigates intelligent drug delivery methods, which encompass stimuli-responsive systems such as temperature, redox, pH, light, enzyme, and magnetic responsive systems. In addition to that, the review goes into topics such as tissue engineering, regenerative medicine, biomedical robotics, automation, biomechanics, and the utilization of green biomaterials. The purpose of this analysis is to provide insights that will enhance continuing research and development efforts in engineering-driven biomedical breakthroughs, ultimately contributing to the improvement of healthcare. These insights will be provided by addressing difficulties and highlighting future prospects.

Impact of Radiation on Invasion and Migration of Glioma In Vitro and In Vivo

Glioblastoma (GBM) constitutes the most common primary brain tumor and it remains incurable despite therapeutic advances. The high infiltration/invasion potential of GBM cells is considered to be one of the reasons for the inevitable recurrence of the disease. Radiotherapy (RT) is part of the standard care for patients with GBM, and its benefits on overall survival are extensively reported. However, numerous preclinical studies show that X-ray irradiation can enhance the motility of GBM cells. In the present review, we bring together state-of-the-art research on the impact of radiation on GBM cell motility. The mechanisms through which irradiation impacts the brain tumor microenvironment and the tumor cells themselves, leading to more aggressive/invasive tumors, are described. Finally, we summarize potential pharmacological strategies to overcome this problem. Clinical data validating the occurrence of these processes are urgently needed as they could be of great value for patient outcomes. With this comprehensive review, we expect to highlight the need for methods which allow for monitoring the post-irradiation invasive behavior of GBM in patients.

Prognostic Role of Invasion-Related Extracellular Matrix Molecules in Diffusely Infiltrating Grade 2 and 3 Astrocytomas

BACKGROUND

Astrocytoma, an IDH-mutant is a common primary brain tumor. Total surgical resection is not feasible due to peritumoral infiltration mediated by extracellular matrix (ECM) molecules.

METHODS

This study aimed at determining the expression pattern of ECM molecules in different prognostic groups of WHO grade 2 and grade 3 patients and identifying the effect of onco-radiotherapy on tumor cell invasion of grade 3 patients. Gene and protein expression of ECM molecules was determined by qRT-PCR and immunohistochemistry, respectively.

RESULTS

In the different prognostic groups of grade 2 tumors HMMR, IDH-1, MKI-67, PDGF-A and versican, in grade 3 tumors integrin α-3, and in both groups integrin α-3 and IDH-1 mRNA expression was significantly different. Regarding protein expression, only integrin αV expression changed significantly in the prognostic groups of grade 2 tumors.

CONCLUSIONS

Based on the invasion spectrum determined by this joint gene and protein expression analysis, there was a sensitivity of 87.5% and a negative predictive value of 88.9% regarding the different prognostic groups of grade 2 astrocytoma. For grade 3 tumors, the applied standard oncotherapeutic modalities apparently lacked significant anti-invasive effects.

Exploiting Integrin-αVβ3 to Enhance Radiotherapy Efficacy in Medulloblastoma via Ferroptosis

Medulloblastoma, a malignant pediatric brain tumor, has a poor prognosis upon relapse, highlighting a critical clinical need. Our previous research linked medulloblastoma cell radioresistance to integrin-αvβ3 expression. β3-depleted (β3_KO) medulloblastoma cells exhibit lipid hydroxyperoxide accumulation after radiotherapy, indicating ferroptosis, a regulated cell death induced by ROS and inhibited by antioxidants such as cysteine, glutathione (GSH), and glutathione peroxidase 4 (GPx4). However, the link between αvβ3 expression, ferroptosis inhibition, and sensitivity to radiotherapy remains unclear. We showed that irradiated β3_KO medulloblastoma cells primarily die by ferroptosis, with β3-subunit expression correlating with radiotherapy sensitivity and anti-ferroptotic protein levels. Our findings suggest that integrin-αvβ3 signaling boosts oxidative stress resilience via mTORC1. Thus, targeting integrin-αvβ3 could enhance radiotherapy efficacy in medulloblastoma by inducing ferroptotic cell death.

Real-time morphometric analysis of targeted therapy for neuroblastoma cells in monolayer and 3D hydrogels using digital holographic microscopy

High-risk neuroblastoma (HR-NB) patient treatment is currently insufficient and challenging due to its high clinical, morphological, and genetic heterogeneity as well as the scarcity of available samples for research. We used a gelatin- and silk fibroin-based hydrogel system with cross-linked vitronectin (VN) as an artificial biomimetic three-dimensional (3D) environment to mirror aggressive neuroblastoma (NB) tumors and tested long-term cell response to Cilengitide (CLG). Based on our previous studies and others using the integrin inhibitor CLG as a potential mechanotherapy drug, we show that CLG caused cell detachment in monolayer cultures of MYCN-amplified SK-N-BE (2) and ALK-mutated SH-SY5Y human neuroblastoma cell lines. Cell detachment and aggregation were maintained in hydrogel-free monolayer cells whereas cells embedded in hydrogels presented different responses to treatment, suggesting differential anoikis resistance between the two cell lines. This underscores the advantages of testing therapeutic approaches using real-time imaging of tumor cells in 3D biomimetic models and its contribution to precision medicine.

The potential of exosomes as a new therapeutic strategy for glioblastoma

Glioblastoma (GBM) stands for the most common and aggressive type of brain tumour in adults. It is highly invasive, which explains its short rate of survival. Little is known about its risk factors, and current therapy is still ineffective. Hence, efforts are underway to develop novel and effective treatment approaches against this type of cancer. Exosomes are being explored as a promising strategy for conveying and delivering therapeutic cargo to GBM cells. They can fuse with the GBM cell membrane and, consequently, serve as delivery systems in this context. Due to their nanoscale size, exosomes can cross the blood-brain barrier (BBB), which constitutes a significant hurdle to most chemotherapeutic drugs used against GBM. They can subsequently inhibit oncogenes, activate tumour suppressor genes, induce immune responses, and control cell growth. However, despite representing a promising tool for the treatment of GBM, further research and clinical studies regarding exosome biology, engineering, and clinical applications still need to be completed. Here, we sought to review the application of exosomes in the treatment of GBM through an in-depth analysis of the scientific and clinical studies on the entire process, from the isolation and purification of exosomes to their design and transformation into anti-oncogenic drug delivery systems. Surface modification of exosomes to enhance BBB penetration and GBM-cell targeting is also a topic of discussion.

Structural insights into the molecular recognition of integrin αVβ3 by RGD-containing ligands: The role of the specificity-determining loop (SDL)

Integrin αVβ3 is a prominent member of the "RGD-recognizing" integrin family of cell surface receptors. αVβ3 binds to various extracellular matrix (ECM) proteins and oxysterols such as 25-hydroxycholesterol, is implicated in several diseases, including cancer metastasis, lung fibrosis, inflammation, and autoimmune diseases, and is pursued as a valuable therapeutic target. Despite enormous efforts to seek a pure antagonist, to date, no single drug candidate has successfully reached clinics due to associated partial agonism and toxicity issues. Developing effective and safe inhibitors require a thorough understanding of the molecular interactions and structural changes related to the receptor's activation and inhibition mechanisms. This study offers a comprehensive residue-residue contact and network analyses of the ligand-binding β-propeller βI domains (headpiece) based on all available experimental structures of integrin αVβ3 in unliganded, agonist-, antagonist-, and antibody-bound states. The analyses reveal many critical interactions that were not reported before and show that specific orientation and interactions of residues from the specificity-determining loop (SDL) are critical in molecular recognition and regulation. Also, the network analysis reveals that residues from the nearby allosteric site (site II) connect to the primary RGD-binding site via SDL, which likely acts as an interface between the two sites. Our results provide valuable insights into molecular interactions, structural changes, distinct features of the active and inactive headpiece conformations, the role of SDL in ligand recognition, and SDL-mediated allostery. Thus, the insights from this study may facilitate the designing of pure antagonists or site II-mediated allosteric modulators to integrin αVβ3 to treat various diseases.

EGFR- and Integrin αVβ3-Targeting Peptides as Potential Radiometal-Labeled Radiopharmaceuticals for Cancer Theranostics

The burgeoning field of cancer theranostics has witnessed advancements through the development of targeted molecular agents, particularly peptides. These agents exploit the overexpression or mutations of specific receptors, such as the Epidermal Growth Factor receptor (EGFR) and αVβ3 integrin, which are pivotal in tumor growth, angiogenesis, and metastasis. Despite the extensive research into and promising outcomes associated with antibody-based therapies, peptides offer a compelling alternative due to their smaller size, ease of modification, and rapid bioavailability, factors which potentially enhance tumor penetration and reduce systemic toxicity. However, the application of peptides in clinical settings has challenges. Their lower binding affinity and rapid clearance from the bloodstream compared to antibodies often limit their therapeutic efficacy and diagnostic accuracy. This overview sets the stage for a comprehensive review of the current research landscape as it relates to EGFR- and integrin αVβ3-targeting peptides. We aim to delve into their synthesis, radiolabeling techniques, and preclinical and clinical evaluations, highlighting their potential and limitations in cancer theranostics. This review not only synthesizes the extant literature to outline the advancements in peptide-based agents targeting EGFR and integrin αVβ3 but also identifies critical gaps that could inform future research directions. By addressing these gaps, we contribute to the broader discourse on enhancing the diagnostic precision and therapeutic outcomes of cancer treatments.

Targeted Radionuclide Therapy in Glioblastoma

Despite the development of various novel therapies, glioblastoma (GBM) remains a devastating disease, with a median survival of less than 15 months. Recently, targeted radionuclide therapy has shown significant progress in treating solid tumors, with the approval of Lutathera for neuroendocrine tumors and Pluvicto for prostate cancer by the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA). This achievement has shed light on the potential of targeted radionuclide therapy for other solid tumors, including GBM. This review presents the current status of targeted radionuclide therapy in GBM, highlighting the commonly used therapeutic radionuclides emitting alpha, beta particles, and Auger electrons that could induce potent molecular and cellular damage to treat GBM. We then explore a range of targeting vectors, including small molecules, peptides, and antibodies, which selectively target antigen-expressing tumor cells with minimal or no binding to healthy tissues. Considering that radiopharmaceuticals for GBM are often administered locoregionally to bypass the blood-brain barrier (BBB), we review prominent delivery methods such as convection-enhanced delivery, local implantation, and stereotactic injections. Finally, we address the challenges of this therapeutic approach for GBM and propose potential solutions.

Peptide-Hitchhiking for the Development of Nanosystems in Glioblastoma

Glioblastoma (GBM) remains the epitome of aggressiveness and lethality in the spectrum of brain tumors, primarily due to the blood-brain barrier (BBB) that hinders effective treatment delivery, tumor heterogeneity, and the presence of treatment-resistant stem cells that contribute to tumor recurrence. Nanoparticles (NPs) have been used to overcome these obstacles by attaching targeting ligands to enhance therapeutic efficacy. Among these ligands, peptides stand out due to their ease of synthesis and high selectivity. This article aims to review single and multiligand strategies critically. In addition, it highlights other strategies that integrate the effects of external stimuli, biomimetic approaches, and chemical approaches as nanocatalytic medicine, revealing their significant potential in treating GBM with peptide-functionalized NPs. Alternative routes of parenteral administration, specifically nose-to-brain delivery and local treatment within the resected tumor cavity, are also discussed. Finally, an overview of the significant obstacles and potential strategies to overcome them are discussed to provide a perspective on this promising field of GBM therapy.

Understanding the Role of Endothelial Cells in Glioblastoma: Mechanisms and Novel Treatments

Glioblastoma is a highly aggressive neoplasm and the most common primary malignant brain tumor. Endothelial tissue plays a critical role in glioblastoma growth and progression, facilitating angiogenesis, cellular communication, and tumorigenesis. In this review, we present an up-to-date and comprehensive summary of the role of endothelial cells in glioblastomas, along with an overview of recent developments in glioblastoma therapies and tumor endothelial marker identification.

A comparison study of dynamic [18F]Alfatide II imaging and [11C]MET in orthotopic rat models of glioblastoma

PURPOSE

To investigate and compare the dynamic positron emission tomography (PET) imaging with [18F]Alfatide II Imaging and [11C]Methionine ([11C]MET) in orthotopic rat models of glioblastoma multiforme (GBM), and to assess the utility of [18F]Alfatide II in detecting and evaluating neoangiogenesis in GBM.

METHODS

[18F]Alfatide II and [11C]MET were injected into the orthotopic GBM rat models (n = 20, C6 glioma cells), followed by dynamic PET/MR scans 21 days after surgery of tumor implantation. On the PET image with both radiotracers, the MRI-based volume-of-interest (VOI) was manually delineated encompassing glioblastoma. Time-activity curves were expressed as tumor-to-normal brain ratio (TNR) parameters and PET pharmacokinetic modeling (PKM) performed using 2-tissue-compartment models (2TCM). Immunofluorescent staining (IFS), western blotting and blocking experiment of tumor tissue were performed for the validation.

RESULTS

Compared to 11C-MET, [18F]Alfatide II presented a persistent accumulation in the tumor, albeit with a slightly lower SUVmean of 0.79 ± 0.25, and a reduced uptake in the contralateral normal brain tissue, respectively. This resulted in a markedly higher tumor-to-normal brain ratio (TNR) of 18.22 ± 1.91. The time-activity curve (TACs) showed a significant increase in radioactive uptake in tumor tissue, followed by a plateau phase up to 60 min for [18F]Alfatide II (time to peak:255 s) and 40 min for [11C]MET (time to peak:135 s) post injection. PKM confirmed significantly higher K1 (0.23/0.07) and K3 (0.26/0.09) in the tumor region compared to the normal brain with [18F]Alfatide II. Compared to [11C]MET imaging, PKM confirmed both significantly higher K1/K2 (1.24 ± 0.79/1.05 ± 0.39) and K3/K4 (11.93 ± 4.28/3.89 ± 1.29) in the tumor region with [18F]Alfatide II. IFS confirmed significant expression of integrin and tumor vascularization in tumor region.

CONCLUSION

[18F]Alfatide II demonstrates potential in imaging tumor-associated neovascularization in the context of glioblastoma multiforme (GBM), suggesting its utility as a tool for further exploration in neovascular characterization.

Integrin-αvβ3 is a Therapeutically Targetable Fundamental Factor in Medulloblastoma Tumorigenicity and Radioresistance

Medulloblastoma is one of the most prevalent solid tumors found in children, occurring in the brain's posterior fossa. The standard treatment protocol involves maximal resection surgery followed by craniospinal irradiation and chemotherapy. Despite a long-term survival rate of 70%, wide disparities among patients have been observed. The identification of pertinent targets for both initial and recurrent medulloblastoma cases is imperative. Both primary and recurrent medulloblastoma are marked by their aggressive infiltration into surrounding brain tissue, robust angiogenesis, and resistance to radiotherapy. While the significant role of integrin-αvβ3 in driving these characteristics has been extensively documented in glioblastoma, its impact in the context of medulloblastoma remains largely unexplored. Integrin-αvβ3 was found to be expressed in a subset of patients with medulloblastoma. We investigated the role of integrin-αvβ3 using medulloblastoma-derived cell lines with β3-subunit depletion or overexpression both in vitro and in vivo settings. By generating radioresistant medulloblastoma cell lines, we uncovered an increased integrin-αvβ3 expression, which correlated with increased susceptibility to pharmacologic integrin-αvβ3 inhibition with cilengitide, a competitive ligand mimetic. Finally, we conducted single-photon emission computed tomography (SPECT)/MRI studies on orthotopic models using a radiolabeled integrin-αvβ3 ligand (99mTc-RAFT-RGD). This innovative approach presents the potential for a novel predictive imaging technique in the realm of medulloblastoma. Altogether, our findings lay the foundation for employing SPECT/MRI to identify a specific subset of patients with medulloblastoma eligible for integrin-αvβ3-directed therapies. This breakthrough offers a pathway toward more targeted and effective interventions in the treatment of medulloblastoma.

SIGNIFICANCE

This study demonstrates integrin-αvβ3's fundamental role in medulloblastoma tumorigenicity and radioresistance and the effect of its expression on cilengitide functional activity.

Advances in molecular targeted therapies to increase efficacy of (chemo)radiation therapy

Recent advances in understanding the tumor's biology in line with a constantly growing number of innovative technologies have prompted characterization of patients' individual malignancies and may display a prerequisite to treat cancer at its patient individual tumor vulnerability. In recent decades, radiation- induced signaling and tumor promoting local events for radiation sensitization were explored in detail, resulting the development of novel molecular targets. A multitude of pharmacological, genetic, and immunological principles, including small molecule- and antibody-based targeted strategies, have been developed that are suitable for combined concepts with radiation (RT) or chemoradiation therapy (CRT). Despite a plethora of promising experimental and preclinical findings, however, so far, only a very limited number of clinical trials have demonstrated a better outcome and/or patient benefit when RT or CRT are combined with targeted agents. The current review aims to summarize recent progress in molecular therapies targeting oncogenic drivers, DNA damage and cell cycle response, apoptosis signaling pathways, cell adhesion molecules, hypoxia, and the tumor microenvironment to impact therapy refractoriness and to boost radiation response. In addition, we will discuss recent advances in nanotechnology, e.g., RNA technologies and protein-degrading proteolysis-targeting chimeras (PROTACs) that may open new and innovative ways to benefit from molecular-targeted therapy approaches with improved efficacy.

Recent Pre-Clinical Advancements in Nuclear Medicine: Pioneering the Path to a Limitless Future

The theranostic approach in oncology holds significant importance in personalized medicine and stands as an exciting field of molecular medicine. Significant achievements have been made in this field in recent decades, particularly in treating neuroendocrine tumors using 177-Lu-radiolabeled somatostatin analogs and, more recently, in addressing prostate cancer through prostate-specific-membrane-antigen targeted radionuclide therapy. The promising clinical results obtained in these indications paved the way for the further development of this approach. With the continuous discovery of new molecular players in tumorigenesis, the development of novel radiopharmaceuticals, and the potential combination of theranostics agents with immunotherapy, nuclear medicine is poised for significant advancements. The strategy of theranostics in oncology can be categorized into (1) repurposing nuclear medicine agents for other indications, (2) improving existing radiopharmaceuticals, and (3) developing new theranostics agents for tumor-specific antigens. In this review, we provide an overview of theranostic development and shed light on its potential integration into combined treatment strategies.

Multi-ligand functionalized blood-to-tumor sequential targeting strategies in the field of glioblastoma nanomedicine

Glioblastoma (GBM) is an unmet clinical need characterized by a standard of care (SOC) 5-year survival rate of only 5%, and a treatment mostly palliative. Significant hurdles in GBM therapies include an effective penetration of therapeutics through the brain protective barrier, namely the blood-brain barrier (BBB), and a successful therapeutic delivery to brain-invading tumor cells post-BBB crossing. These hurdles, along with the poor prognosis and critical heterogeneity of the disease, have shifted attention to treatment modalities with capacity to precisely and sequentially target (i) BBB cells, inducing blood-to-brain transport, and (ii) GBM cells, leading to a higher therapeutic accumulation at the tumor site. This sequential targeting allows therapeutic molecules to reach the brain parenchyma and compromise molecular processes that support tumor cell invasion. Besides improving formulation and pharmacokinetics constraints of drugs, nanomedicines offer the possibility of being surface functionalized with multiple possibilities of targeting ligands, while delivering the desired therapeutic cargos to the biological sites of interest. Targeting ligands exploit the site-specific expression or overexpression of specific molecules on BBB and GBM cells, triggering brain plus tumor transport. Since the efficacy of single-ligand functionalized nanomedicines is limited due to the GBM anatomical site (brain) and disease complexity, this review presents an overview of multi-ligand functionalized, BBB and GBM sequentially- and dual-targeted nanomedicines reported in literature over the last 10 years. The role of the BBB in GBM progression, treatment options, and the multiple possibilities of currently available targeting ligands will be summarized. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Mechanisms of Resistance and Current Treatment Options for Glioblastoma Multiforme (GBM)

Glioblastoma multiforme (GBM) is a highly aggressive form of brain cancer that is difficult to treat due to its resistance to both radiation and chemotherapy. This resistance is largely due to the unique biology of GBM cells, which can evade the effects of conventional treatments through mechanisms such as increased resistance to cell death and rapid regeneration of cancerous cells. Additionally, the blood–brain barrier makes it difficult for chemotherapy drugs to reach GBM cells, leading to reduced effectiveness. Despite these challenges, there are several treatment options available for GBM. The standard of care for newly diagnosed GBM patients involves surgical resection followed by concurrent chemoradiotherapy and adjuvant chemotherapy. Emerging treatments include immunotherapy, such as checkpoint inhibitors, and targeted therapies, such as bevacizumab, that attempt to attack specific vulnerabilities in GBM cells. Another promising approach is the use of tumor-treating fields, a type of electric field therapy that has been shown to slow the growth of GBM cells. Clinical trials are ongoing to evaluate the safety and efficacy of these and other innovative treatments for GBM, intending to improve with outcomes for patients.

Amino Acid Tracer PET MRI in Glioma Management: What a Neuroradiologist Needs to Know

PET with amino acid tracers provides additional insight beyond MR imaging into the biology of gliomas that can be used for initial diagnosis, delineation of tumor margins, planning of surgical and radiation therapy, assessment of residual tumor, and evaluation of posttreatment response. Hybrid PET MR imaging allows the simultaneous acquisition of various PET and MR imaging parameters in a single investigation with reduced scanning time and improved anatomic localization. This review aimed to provide neuroradiologists with a concise overview of the various amino acid tracers and a practical understanding of the clinical applications of amino acid PET MR imaging in glioma management. Future perspectives in newer advances, novel radiotracers, radiomics, and cost-effectiveness are also outlined.

PET tracers in glioblastoma: Toward neurotheranostics as an individualized medicine approach

Over the past decade, theragnostic radiopharmaceuticals have been used in nuclear medicine for both diagnosis and treatment of various tumors. In this review, we carried out a literature search to investigate and explain the role of radiotracers in the theragnostic approach to glioblastoma multiform (GBM). We primarily focused on basic and rather common positron emotion tomography (PET) radiotracers in these tumors. Subsequently, we introduced and evaluated the preclinical and clinical results of theranostic-based biomarkers including integrin receptor family, prostate-specific membrane antigen (PSMA), fibroblast activated protein (FAP), somatostatin receptors (SRS), and chemokine receptor-4 (CXCR4) for patients with GBM to confer the benefit of personalized therapy. Moreover, promising research opportunities that could have a profound impact on the treatment of GBM over the next decade are also highlighted. Preliminary results showed the potential feasibility of the theragnostic approach using theses biomarkers in GBM patients.

Observation of the protein expression level via naked eye: Pt clusters catalyze non-color molecules into brown-colored molecules in cells

α _v β ₃ is overexpressed in various tumor cells and plays a key role in tumor genesis, invasion, and metastasis. Therefore, it is of great significance to precisely detect the α _v β ₃ level in cells via a simple method. For this purpose, we have constructed a peptide-coated platinum (Pt) cluster. Due to its bright fluorescence, well-defined Pt atom numbers, and peroxidase-like catalytic activity, this cluster can be used to evaluate α _v β ₃ levels in cells by fluorescence imaging, inductively coupled plasma mass spectrometry (ICP-MS), and catalytic amplification of visual dyes, respectively. In this report, the expression level of α _v β ₃ in living cells is well-detected by the naked eye under an ordinary light microscope when the Pt cluster binds to αvβ3 in cells and catalyzes non-color 3,3'-diaminobenzidine (DAB) into brown-colored molecules in situ. Moreover, SiHa, HeLa, and 16HBE cell lines with different α _v β ₃ expression levels can be visually distinguished by the peroxidase-like Pt clusters. This research will provide a reliable method for the simple detection of α _v β ₃ levels in cells.

[Study of the efficiency of cellular accumulation of doxorubicin supplied with a targeted delivery system based on phospholipid nanoparticles with integrin-directed peptide]

Chemotherapeutic agents containing targeted systems are a promising pathway to increase the effectiveness of glioblastoma treatment. Specific proteins characterized by increased expression on the surface of tumor cells are considered as possible targets. Integrin αvβ3 is one of such proteins on the cell surface. It effectively binds the cyclic Arg-Gly-Asp (cRGD) peptide. In this study, the cRGD peptide-modified doxorubicin (Dox) phospholipid composition was investigated. The particle size of this composition was 43.76±2.09 nm, the ζ-potential was 4.33±0.54 mV. Dox was almost completely incorporated into the nanoparticles (99.7±0.58%). The drug release increased in an acidic medium (at pH 5.0 of about 35±3.2%). The total accumulation and internalization of Dox used the composition of phospholipid nanoparticles with the targeted vector was 1.4-fold higher as compared to the free form. In the HeLa cell line (not expressing αvβ3 integrin) this effect was not observed. These results suggest the prospects of using the cyclic RGD peptide in the delivery of Dox to glioblastoma cells and the feasibility of further investigation of the mechanism of action of the entire composition as a whole.

Internalisation of RGD-Engineered Extracellular Vesicles by Glioblastoma Cells

Simple Summary

Glioblastoma multiforme (GBM) is the most aggressive and malignant type of central nervous system (CNS) tumour. Although several treatment options are available, patients generally succumb within 14 months after diagnosis. With the rapid progression of exosome bioengineering technologies, novel therapy opportunities are emerging for GBM treatment. The surface of GBM cells is characterised by the overexpression of transmembrane receptor integrins, which are essential for cell interactions with several proteins in the extracellular matrix. Therefore, integrin-binding drug delivery vehicles have been proposed as a potential strategy for glioblastoma therapy. Small extracellular vesicles possess several attractive characteristics for drug delivery: small size, biocompatibility, ability to cross the blood–brain barrier and capacity to be loaded with exogenous materials. Current bioengineering technologies further increase extracellular vesicle capabilities by loading them with anticancer drugs and incorporating targeting ligands. This study explored the capacity of Arginylglycylaspartic acid (RGD, or Arginine–Glycine–Aspartate)-polypeptide-engineered extracellular vesicles to internalise and deliver loaded cargo in GBM cells. The results demonstrate that introducing the RGD ligand to extracellular vesicles could significantly increase their internalisation by GBM cells and hence improve drug delivery efficacy.

Abstract

Glioblastoma multiforme (GBM) is the most aggressive CNS tumour with no efficient treatment, partly due to the retention of anticancer drugs by the blood–brain barrier (BBB) and their insufficient concentration in tumour cells. Extracellular vesicles (EVs) are attractive drug carriers because of their biocompatibility and ability to cross the BBB. Additional efficiency can be achieved by adding GBM-cell-specific ligands. GBM cells overexpress integrins; thus, one of the most straightforward targeting strategies is to modify EVs with integrin-recognising molecules. This study investigated the therapeutic potential of genetically engineered EVs with elevated membrane levels of the integrin-binding peptide RGD (RGD-EVs) against GBM cells in vitro. For RGD-EV production, stable RGD-HEK 293FT cells were generated by using a pcDNA4/TO-Lamp2b-iRGD-HA expression vector and performing antibiotic-based selection. RGD-EVs were isolated from RGD-HEK 293FT-cell-conditioned medium and characterised by size (Zetasizer), specific markers (ELISA) and RGD expression (Western Blot). Internalisation by human GBM cells HROG36 and U87 MG and BJ-5ta human fibroblasts was assessed by fluorescent EV RNA labelling. The effect of doxorubicin-loaded RGD-EVs on GBM cells was evaluated by the metabolic PrestoBlue viability assay; functional GAPDH gene knockdown by RGD-EV-encapsulated siRNA was determined by RT-qPCR. RGD-EVs had 40% higher accumulation in GBM cells (but not in fibroblasts) and induced significantly stronger toxicity by loaded doxorubicin and GAPDH silencing by loaded siRNA compared to unmodified EVs. Thus, RGD modification substantially increases the specific delivery capacity of HEK 293FT-derived EVs to GBM cells.

Identification of Prognostic Genes in Gliomas Based on Increased Microenvironment Stiffness

With a median survival time of 15 months, glioblastoma multiforme is one of the most aggressive primary brain cancers. The crucial roles played by the extracellular matrix (ECM) stiffness in glioma progression and treatment resistance have been reported in numerous studies. However, the association between ECM-stiffness-regulated genes and the prognosis of glioma patients remains to be explored. Thus, using bioinformatics analysis, we first identified 180 stiffness-dependent genes from an RNA-Seq dataset, and then evaluated their prognosis in The Cancer Genome Atlas (TCGA) glioma dataset. Our results showed that 11 stiffness-dependent genes common between low- and high-grade gliomas were prognostic. After validation using the Chinese Glioma Genome Atlas (CGGA) database, we further identified four stiffness-dependent prognostic genes: FN1, ITGA5, OSMR, and NGFR. In addition to high-grade glioma, overexpression of the four-gene signature also showed poor prognosis in low-grade glioma patients. Moreover, our analysis confirmed that the expression levels of stiffness-dependent prognostic genes in high-grade glioma were significantly higher than in low-grade glioma, suggesting that these genes were associated with glioma progression. Based on a pathophysiology-inspired approach, our findings illuminate the link between ECM stiffness and the prognosis of glioma patients and suggest a signature of four stiffness-dependent genes as potential therapeutic targets.