Synergistic inhibition of tumor growth by combination treatment with drugs against different subpopulations of glioblastoma cells

An Overview of CD133 as a Functional Unit of Prognosis and Treatment Resistance in Glioblastoma

Biomarkers for resistance in Glioblastoma multiforme (GBM) are lacking, and progress in the clinic has been slow to arrive. CD133 (prominin-1) is a membrane-bound glycoprotein on the surface of cancer stem cells (CSCs) that has been associated with poor prognosis, therapy resistance, and tumor recurrence in GBM. Due to its connection to CSCs, to which tumor resistance and recurrence have been partially attributed in GBM, there is a growing field of research revolving around the potential role of CD133 in each of these processes. However, despite encouraging results in vitro and in vivo, the biological interplay of CD133 with these components is still unclear, causing a lack of clinical application. In parallel, omic data from biospecimens that include CD133 are beginning to emerge, increasing the importance of understanding CD133 for the effective use of these highly dimensional data sets. Given the significant mechanistic overlap, prioritization of the most robust findings is necessary to optimize the transition of CD133 to clinical applications using patient-derived biospecimens. As a result, this review aims to compile and analyze the current research regarding CD133 as a functional unit in GBM, exploring its connections to prognosis, the tumor microenvironment, tumor resistance, and tumor recurrence.

Cisplatin and Albumin-Based Gold-Cisplatin Nanoparticles Enhance Ablative Radiation Therapy-Induced Antitumor Immunity in Local and Distant Tumor Microenvironment

PURPOSE

Ablative radiation therapy (RT) is an important strategy to eliminate primary tumor and can potentially induce the abscopal effect. Human serum albumin nanoparticle (NP) was used for controlled release of cisplatin to decrease cisplatin's systemic toxicity, and gold (Au) was added to increase RT-induced immunogenic cell death and potentiate the abscopal antitumor immunity.

METHODS AND MATERIALS

The designed albumin-based cisplatin-conjugated AuNPs were administered concurrently with ablative RT. C57BL/6 mice implanted with syngeneic murine Lewis lung carcinoma or murine MB49 tumor models were treated with ablative RT (12 Gy per fraction for 2 fractions, total 24 Gy), cisplatin, or Au-cisplatin NPs.

RESULTS

Combining ablative RT with cisplatin or Au-cisplatin NPs both destroyed the primary tumor effectively and elicited immunogenic cell death accompanied by release of danger-associated molecular patterns. This enhanced recruitment of effector tumor-infiltrating immune cells, including natural killer T cells and CD8+ T cells, and elicited an increased percentage of professional antigen-presenting CD11c+ dendritic cells. Transient weight loss, accompanying hepatotoxicity, nephrotoxicity, and hematopoietic suppression, was observed as a systemic adverse event in the cisplatin but not the Au-cisplatin NPs group. Cisplatin and Au-cisplatin NPs both showed equivalent ability to reduce metastatic potential when combined with ablative RT, confirmed by suppressed unirradiated flank tumor growth and decreased metastatic lung tumor burden, which translated to improved survival. Mobilization and abundance of effector tumor-infiltrating immune cells including CD8+ T cells and dendritic cells were observed in the distant lung tumor microenvironment after ablative RT with cisplatin or Au-cisplatin NPs, demonstrating increased antitumor immunotherapeutic activity as an abscopal effect.

CONCLUSIONS

Compared with cisplatin, the albumin-based Au-cisplatin NPs exhibited equivalent but no superior antitumor immunotherapeutic activity while reducing systemic adverse events and can be safely administered concurrently with ablative RT. Alternative NP formulations may be designed to further improve anticancer outcomes.

Independent Drug Action in Combination Therapy: Implications for Precision Oncology

Combination therapies are superior to monotherapy for many cancers. This advantage was historically ascribed to the ability of combinations to address tumor heterogeneity, but synergistic interaction is now a common explanation as well as a design criterion for new combinations. We review evidence that independent drug action, described in 1961, explains the efficacy of many practice-changing combination therapies: it provides populations of patients with heterogeneous drug sensitivities multiple chances of benefit from at least one drug. Understanding response heterogeneity could reveal predictive or pharmacodynamic biomarkers for more precise use of existing drugs and realize the benefits of additivity or synergy.

Minocycline in Treating Glioblastoma Multiforme: Far beyond a Conventional Antibiotic

One of the most lethal forms of CNS pathologies is glioblastoma multiforme (GBM) that represents high invasiveness, uncontrolled proliferation, and angiogenic features. Its invasiveness is responsible for the high recurrence even after maximal surgical interventions. Minocycline is a semisynthetic analog of tetracyclines with potential anti-inflammatory and anticancer effects, distinct from its antimicrobial activity. In this review, we highlight the importance and the cytotoxic mechanisms of minocycline on GBM pathophysiology. Considering the role of certain enzymes in autophagy, apoptosis, tumor cell invasion, and metastatic ability, the possible use of tetracyclines for cancer therapy should be investigated, especially GBM. The present study is, therefore, going to cover the main topics in minocycline pharmacology to date, encouraging its consideration as a new treatment approach for cancer and GBM.

Inhibition of Sonic Hedgehog Signaling Suppresses Glioma Stem-Like Cells Likely Through Inducing Autophagic Cell Death

Glioblastoma (GBM) often recurs after radio- and chemotherapies leading to poor prognosis. Glioma stem-like cells (GSCs) contribute to drug resistance and recurrence. Thus, understanding cellular mechanism underlying the growth of GSCs is critical for the treatment of GBM. Here GSCs were isolated from human U87 GBM cells with magnetic-activated cell sorting (MACS) using CD133 as a marker. The CD133⁺ cells highly expressed sonic hedgehog (Shh) and were capable of forming tumor spheroids in vitro and tumor in vivo. Athymic mice received intracranial injection of luciferase transduced parental and CD133⁺ GBM cells was utilized as orthotopic GBM model. Inhibited Shh by LDE225 delayed GBM growth in vivo, and downregulated Ptch1 and Gli1. CD133⁺ cell proliferation was more sensitive to inhibition by LDE225 than that of CD133⁻ cells. Treatment with LDE225 significantly reduced CD133⁺-derived tumor spheroid formation. Large membranous vacuoles appeared in the LDE225-treated cells concomitant with the conversion of LC3-I to LC3-II. In addition, LDE225-induced cell death was mitigated in the presence of autophagy inhibitor 3-methyladenine (3-MA). Tumor growth was much slower in Shh shRNA-knockdown mice than in control RNA-transfected mice. Conversely, tumor growth was faster in Shh overexpressed mice. Furthermore, combination of LDE225 and rapamycin treatment resulted in additive effect on LC3-I to LC3-II conversion and reduction in cell viability. However, LDE225 did not affect the phosphorylated level of mTOR. Similarly, amiodarone, an mTOR-independent autophagy enhancer, reduced CD133⁺ cell viability and tumor spheroid formation in vitro and exhibited anti-tumor activity in vivo. These results suggest that Shh inhibitor induces autophagy of CD133⁺ cells likely through mTOR independent pathway. Targeting Shh signal pathway may overcome chemoresistance and provide a therapeutic strategy for patients with malignant gliomas.

Hypoxic Environment and Paired Hierarchical 3D and 2D Models of Pediatric H3.3-Mutated Gliomas Recreate the Patient Tumor Complexity

BACKGROUND

Pediatric high-grade gliomas (pHGGs) are facing a very dismal prognosis and representative pre-clinical models are needed for new treatment strategies. Here, we examined the relevance of collecting functional, genomic, and metabolomics data to validate patient-derived models in a hypoxic microenvironment.

METHODS

From our biobank of pediatric brain tumor-derived models, we selected 11 pHGGs driven by the histone H3.3K28M mutation. We compared the features of four patient tumors to their paired cell lines and mouse xenografts using NGS (next generation sequencing), aCGH (array comparative genomic hybridization), RNA sequencing, WES (whole exome sequencing), immunocytochemistry, and HRMAS (high resolution magic angle spinning) spectroscopy. We developed a multicellular in vitro model of cell migration to mimic the brain hypoxic microenvironment. The live cell technology Incucyte© was used to assess drug responsiveness in variable oxygen conditions.

RESULTS

The concurrent 2D and 3D cultures generated from the same tumor sample exhibited divergent but complementary features, recreating the patient intra-tumor complexity. Genomic and metabolomic data described the metabolic changes during pHGG progression and supported hypoxia as an important key to preserve the tumor metabolism in vitro and cell dissemination present in patients. The neurosphere features preserved tumor development and sensitivity to treatment.

CONCLUSION

We proposed a novel multistep work for the development and validation of patient-derived models, considering the immature and differentiated content and the tumor microenvironment of pHGGs.

Clinical and Prognostic Significance of Cell Sensitivity to Chemotherapy Detected in vitro on Treatment Response and Survival of Leukemia Patients

Multidrug resistance (MDR) is a major challenge in leukemia treatment. The objective of this study was to identity predictors of MDR to allow for rapid and economical assessment of the efficacy of planned antitumor therapy for leukemia patients. The study included 113 patients with acute and chronic leukemias. Prior to antitumor therapy, we measured the sensitivity of tumor cells of patients to the panel of chemotherapeutic drugs, together with MDR1 mRNA and P-glycoprotein (P-gp) expression as one of the mechanisms of MDR, and compared these data with the response to therapy. The scales for leukemia patients according to therapy response, drug sensitivity of tumor cells, MDR1 mRNA and P-gp levels, and the presence of unfavorable immunological and cytogenetic markers were introduced for subsequent correlation analysis. We show that the drug resistance of tumor cells of leukemia patients estimated in vitro at diagnosis correlates with a poor response to chemotherapy and is usually combined with aberrant and immature immunological markers, cytogenetic abnormalities, and a high expression of MDR1 mRNA and P-gp. All together, these factors indicate unfavorable prognosis and low survival of leukemia patients. Thus, the sensitivity of tumor cells to chemotherapeutic drugs measured in vitro at diagnosis may have prognostic value for individual types of leukemia.

Co-Administered Polymeric Nano-Antidotes for Improved Photo-Triggered Response in Glioblastoma

Polymer-based nanoparticles (NPs) are useful vehicles in treating glioblastoma because of their favorable characteristics such as small size and ability to cross the blood–brain barrier, as well as reduced immunogenicity and side effects. The use of a photosensitizer drug such as Verteporfin (BPD), in combination with a pan-vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitor (TKI), Cediranib (CED), encapsulated in NPs will provide the medical field with new research on the possible ways to treat glioblastoma. Concomitant administration of BPD and CED NPs have the potential to induce dual photocytotoxic and cytostatic effects in U87 MG cells by (1) remotely triggering BPD through photodynamic therapy by irradiating laser at 690 nm and subsequent production of reactive oxygen species and (2) inhibiting cell proliferation by VEGFR interference and growth factor signaling mechanisms which may allow for longer progression free survival in patients and fewer systemic side effects. The specific aims of this research were to synthesize, characterize and assess cell viability and drug interactions for polyethylene-glycolated (PEGylated) polymeric based CED and BPD NPs which were less than 100 nm in size for enhanced permeation and retention effects. Synergistic effects were found using the co-administered therapies compared to the individual drugs. The major goal of this research was to investigate a new combination of photodynamic-chemotherapy drugs in nano-formulation for increased efficacy in glioblastoma treatment at reduced concentrations of therapeutics for enhanced drug delivery in vitro.

Cellular and Molecular Heterogeneity Associated with Vessel Formation Processes

The microvasculature heterogeneity is a complex subject in vascular biology. The difficulty of building a dynamic and interactive view among the microenvironments, the cellular and molecular heterogeneities, and the basic aspects of the vessel formation processes make the available knowledge largely fragmented. The neovascularisation processes, termed vasculogenesis, angiogenesis, arteriogenesis, and lymphangiogenesis, are important to the formation and proper functioning of organs and tissues both in the embryo and the postnatal period. These processes are intrinsically related to microvascular cells, such as endothelial and mural cells. These cells are able to adjust their activities in response to the metabolic and physiological requirements of the tissues, by displaying a broad plasticity that results in a significant cellular and molecular heterogeneity. In this review, we intend to approach the microvasculature heterogeneity in an integrated view considering the diversity of neovascularisation processes and the cellular and molecular heterogeneity that contribute to microcirculatory homeostasis. For that, we will cover their interactions in the different blood-organ barriers and discuss how they cooperate in an integrated regulatory network that is controlled by specific molecular signatures.

LAMP-1 gene is overexpressed in high grade glioma

High-grade gliomas (HGG) are the most frequent brain tumors in adults. Glioblastoma multiforme (GBM) is their most aggressive form resistant to therapy. It was shown that inhibition of autophagy reduced GBM development and autophagy interfering agents are regarded as a new strategy to fight glioma cells. The lysosome-associated membrane proteins (LAMPs) display differential expression particularly in cancer. There are few data on their expression and especially on their molecular profile. The aim of the present study is to investigate the expression of LAMP-1 and LAMP-2 genes and proteins in HGG. Newly diagnosed patients with HGG and healthy controls were examined by immunohistochemistry and qPCR for both protein and mRNA levels of LAMP-1 and LAMP-2. The transcriptional activity of LAMP-1 in HGG was significantly higher compared to normal brain and to LAMP-2. The two glycoproteins were detected in the cytosol of tumor cells with varying intensity, LAMP-1 showing again enhanced expression. In conclusion, novel data on LAMP-1 overexpression in HGG are presented suggesting involvement of this gene and protein in cell adhesion and tumor progression. These findings might help the elucidation of the complex biological role of the multifunctional LAMPs proteins and to predict novel therapeutic targets in lysosomes.