Combination therapy with micellarized cyclopamine and temozolomide attenuate glioblastoma growth through Gli1 down-regulation

Conditioned Medium From Reactive Astrocytes Inhibits Proliferation, Resistance, and Migration of p53-Mutant Glioblastoma Spheroid Through GLI-1 Downregulation

Glioblastoma (GBM) aggressiveness is partly driven by the reactivation of signaling pathways such as Sonic hedgehog (SHH) and the interaction with its microenvironment. SHH pathway activation is one of the phenomena behind the glial transformation in response to tumor growth. The reactivation of the SHH signaling cascade during GBM-astrocyte interaction is highly relevant to understanding the mechanisms used by the tumor to modulate the adjacent stroma. The role of reactive astrocytes considering SHH signaling during GBM progression is investigated using a 3D in vitro model. T98G GBM spheroids displayed significant downregulation of SHH (61.4 ± 9.3%), GLI-1 (6.5 ± 3.7%), Ki-67 (33.7 ± 8.1%), and mutant MTp53 (21.3 ± 10.6%) compared to the CONTROL group when incubated with conditioned medium of reactive astrocytes (CM-AST). The SHH pathway inhibitor, GANT-61, significantly reduced previous markers (SHH = 43.0 ± 12.1%; GLI-1 = 9.5 ± 3.4%; Ki-67 = 31.9 ± 4.6%; MTp53 = 6.5 ± 7.5%) compared to the CONTROL, and a synergistic effect could be observed between GANT-61 and CM-AST. The volume (2.0 ± 0.2 × 107 µm³), cell viability (80.4 ± 3.2%), and migration (41 ± 10%) of GBM spheroids were significantly reduced in the presence of GANT-61 and CM-AST when compared to CM-AST after 72 h (volume = 2.3 ± 0.4 × 107 µm³; viability = 92.2 ± 6.5%; migration = 102.5 ± 14.6%). Results demonstrated that factors released by reactive astrocytes promoted a neuroprotective effect preventing GBM progression using a 3D in vitro model potentiated by SHH pathway inhibition.

Pediatric versus adult high grade glioma: Immunotherapeutic and genomic considerations

High grade gliomas are identified as malignant central nervous tumors that spread rapidly and have a universally poor prognosis. Historically high grade gliomas in the pediatric population have been treated similarly to adult high grade gliomas. For the first time, the most recent classification of central nervous system tumors by World Health Organization has divided adult from pediatric type diffuse high grade gliomas, underscoring the biologic differences between these tumors in different age groups. The objective of our review is to compare high grade gliomas in the adult versus pediatric patient populations, highlighting similarities and differences in epidemiology, etiology, pathogenesis and therapeutic approaches. High grade gliomas in adults versus children have varying clinical presentations, molecular biology background, and response to chemotherapy, as well as unique molecular targets. However, increasing evidence show that they both respond to recently developed immunotherapies. This review summarizes the distinctions and commonalities between the two in disease pathogenesis and response to therapeutic interventions with a focus on immunotherapy.

Hedgehog signaling regulates the development and treatment of glioblastoma

Glioblastoma (GBM) is the most common and fatal malignant tumor type of the central nervous system. GBM affects public health and it is important to identify biomarkers to improve diagnosis, reduce drug resistance and improve prognosis (e.g., personalized targeted therapies). Hedgehog (HH) signaling has an important role in embryonic development, tissue regeneration and stem cell renewal. A large amount of evidence indicates that both normative and non-normative HH signals have an important role in GBM. The present study reviewed the role of the HH signaling pathway in the occurrence and progression of GBM. Furthermore, the effectiveness of drugs that target different components of the HH pathway was also examined. The HH pathway has an important role in reversing drug resistance after GBM conventional treatment. The present review highlighted the relevance of HH signaling in GBM and outlined that this pathway has a key role in the occurrence, development and treatment of GBM.

Combined Effects of Doxorubicin and Temozolomide in Cultured Glioblastoma Cells

The oncological field benefits of extensive medical research and various types of cancer notice improvements, however glioblastoma multiforme remains one of the deadliest cancers in humans with virtually no advance in survival and clinical outcome. Temozolomide, the FDA approved drug for glioblastoma, faces numerous challenges such as resistance and side effects. To overcome these challenges, many combination therapies are currently studied. The present study analyses the effects of temozolomide in combination with doxorubicin on a glioblastoma cell line. Our results showed that both drugs displayed a cytotoxic effect on the studied cells in single administration (55% for 100μM temozolomide at 14 days, 53% for 100μM doxorubicin at 14 days), but without a synergistic effect in dual therapy. Although the results failed to produce the expected effect, they propose new research perspectives in the future.

The Impact of Astrocytes and Endothelial Cells on Glioblastoma Stemness Marker Expression in Multicellular Spheroids

Introduction

Glioblastoma multiforme (GBM), the most common primary brain tumor in adults, is extremely malignant and lethal. GBM tumors are highly heterogenous, being comprised of cellular and matrix components, which contribute to tumor cell invasion, cancer stem cell maintenance, and drug resistance. Here, we developed a heterotypic 3D spheroid model integrating GBM cells with astrocytes and endothelial cells (ECs) to better simulate the cellular components of the tumor microenvironment and investigate their impact on the stemness marker expression of GBM cells, which has not been previously investigated.

Methods

We used U87 GBM cells, C8-D1A mouse astrocytes, and human umbilical vein ECs to construct co- and tri-culture spheroid models in low-attachment U-well plates. We characterized the expression of known stemness markers NESTIN, SOX2, CD133, NANOG, and OCT4 in these models and compared it to respective mixed monoculture spheroids (control) using qRT-PCR and immunostaining.

Results

We incorporated GBM cells and astrocytes/ECs in 1:1, 1:2, 1:4, and 1:9 ratio and observed spontaneous self-assembled spheroids in all coculture conditions. We observed changing spheroid size dynamics over 7 days and an increased expression in stemness markers in GBM-astrocyte and GBM-EC coculture spheroids in 1:4 and 1:9 coculture conditions, respectively. In a triculture model employing GBM cells, astrocytes, and ECs in a 1:4:9 ratio, we found an increased expression of all the stemness markers.

Conclusions

We elucidated the impact of astrocytes and ECs on GBM stemness marker expression. This multicellular spheroid model may provide an important tool for investigating the crosstalk between cell types in GBM.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12195-021-00691-y.

Glioma Stem-Like Cells and Metabolism: Potential for Novel Therapeutic Strategies

Glioma stem-like cells (GSCs) were first described as a population which may in part be resistant to traditional chemotherapeutic therapies and responsible for tumour regrowth. Knowledge of the underlying metabolic complexity governing GSC growth and function may point to potential differences between GSCs and the tumour bulk which could be harnessed clinically. There is an increasing interest in the direct/indirect targeting or reprogramming of GSC metabolism as a potential novel therapeutic approach in the adjuvant or recurrent setting to help overcome resistance which may be mediated by GSCs. In this review we will discuss stem-like models, interaction between metabolism and GSCs, and potential current and future strategies for overcoming GSC resistance.

Connexin 43 and Sonic Hedgehog Pathway Interplay in Glioblastoma Cell Proliferation and Migration

Simple Summary

Glioblastoma is the product of accumulated genetic and epigenetic alteration where tumor cells support each other through cellular communication mechanisms and deregulated signalling processes. The autocrine and paracrine pathways between the intracellular and extracellular milieu is mediated by connexin 43, the main gap junction-forming protein driving glioblastoma progression. In this scenario, sonic hedgehog pathway, a key deregulated pathway involved in cell network signalling may affect connexin 43 expression, promoting glioblastoma pathobiology. In this study, we sought to explore how the modulation of the sonic hedgehog affects connexin 43 inducing glioblastoma hallmarks. To do this we evaluated biological effects of sonic hedgehog pathway modulation by purmorphamine and cyclopamine, a smoothened agonist and antagonist, respectively. We revealed that cell migration and proliferation are associated with connexin 43 expression upon sonic hedgehog modulation. Our study suggests that sonic hedgehog and connexin 43 axis may represent a potential therapeutic strategy for glioblastoma.

Abstract

Glioblastoma (GBM) represents the most common primary brain tumor within the adult population. Current therapeutic options are still limited by high rate of recurrences and signalling axes that promote GBM aggressiveness. The contribution of gap junctions (GJs) to tumor growth and progression has been proven by experimental evidence. Concomitantly, tumor microenvironment has received increasing interest as a critical process in dysregulation and homeostatic escape, finding a close link between molecular mechanisms involved in connexin 43 (CX43)-based intercellular communication and tumorigenesis. Moreover, evidence has come to suggest a crucial role of sonic hedgehog (SHH) signalling pathway in GBM proliferation, cell fate and differentiation. Herein, we used two human GBM cell lines, modulating SHH signalling and CX43-based intercellular communication in in vitro models using proliferation and migration assays. Our evidence suggests that modulation of the SHH effector smoothened (SMO), by using a known agonist (i.e., purmorphamine) and a known antagonist (i.e., cyclopamine), affects the CX43 expression levels and therefore the related functions. Moreover, SMO activation also increased cell proliferation and migration. Importantly, inhibition of CX43 channels was able to prevent SMO-induced effects. SHH pathway and CX43 interplay acts inducing tumorigenic program and supporting cell migration, likely representing druggable targets to develop new therapeutic strategies for GBM.

A Systematic Review of Glioblastoma-Targeted Therapies in Phases II, III, IV Clinical Trials

Glioblastoma (GBM), the most frequent and aggressive glial tumor, is currently treated as first line by the Stupp protocol, which combines, after surgery, radiotherapy and chemotherapy. For recurrent GBM, in absence of standard treatment or available clinical trials, various protocols including cytotoxic drugs and/or bevacizumab are currently applied. Despite these heavy treatments, the mean overall survival of patients is under 18 months. Many clinical studies are underway. Based on clinicaltrials.org and conducted up to 1 April 2020, this review lists, not only main, but all targeted therapies in phases II-IV of 257 clinical trials on adults with newly diagnosed or recurrent GBMs for the last twenty years. It does not involve targeted immunotherapies and therapies targeting tumor cell metabolism, that are well documented in other reviews. Without surprise, the most frequently reported drugs are those targeting (i) EGFR (40 clinical trials), and more generally tyrosine kinase receptors (85 clinical trials) and (ii) VEGF/VEGFR (75 clinical trials of which 53 involving bevacizumab). But many other targets and drugs are of interest. They are all listed and thoroughly described, on an one-on-one basis, in four sections related to targeting (i) GBM stem cells and stem cell pathways, (ii) the growth autonomy and migration, (iii) the cell cycle and the escape to cell death, (iv) and angiogenesis.

Inhibiting the Growth of 3D Brain Cancer Models with Bio-Coronated Liposomal Temozolomide

Nanoparticles (NPs) have emerged as an effective means to deliver anticancer drugs into the brain. Among various forms of NPs, liposomal temozolomide (TMZ) is the drug-of-choice for the treatment and management of brain tumours, but its therapeutic benefit is suboptimal. Although many possible reasons may account for the compromised therapeutic efficacy, the inefficient tumour penetration of liposomal TMZ can be a vital obstacle. Recently, the protein corona, i.e., the layer of plasma proteins that surround NPs after exposure to human plasma, has emerged as an endogenous trigger that mostly controls their anticancer efficacy. Exposition of particular biomolecules from the corona referred to as protein corona fingerprints (PCFs) may facilitate interactions with specific receptors of target cells, thus, promoting efficient internalization. In this work, we have synthesized a set of four TMZ-encapsulating nanomedicines made of four cationic liposome (CL) formulations with systematic changes in lipid composition and physical−chemical properties. We have demonstrated that precoating liposomal TMZ with a protein corona made of human plasma proteins can increase drug penetration in a 3D brain cancer model derived from U87 human glioblastoma multiforme cell line leading to marked inhibition of tumour growth. On the other side, by fine-tuning corona composition we have also provided experimental evidence of a non-unique effect of the corona on the tumour growth for all the complexes investigated, thus, clarifying that certain PCFs (i.e., APO-B and APO-E) enable favoured interactions with specific receptors of brain cancer cells. Reported results open new perspectives into the development of corona-coated liposomal drugs with enhanced tumour penetration and antitumour efficacy.

Tubastatin A, an inhibitor of HDAC6, enhances temozolomide‑induced apoptosis and reverses the malignant phenotype of glioblastoma cells

Glioblastoma or grade IV astrocytoma is the most common and lethal form of glioma. Current glioblastoma treatment strategies use surgery followed by chemotherapy with temozolomide. Despite this, numerous glioblastoma cases develop resistance to temozolomide treatments, resulting in a poor prognosis for the patients. Novel approaches are being investigated, including the inhibition of histone deacetylase 6 (HDAC6), an enzyme that deacetylates α‑tubulin, and whose overexpression in glioblastoma is associated with the loss of primary cilia. The aim of the present study was to treat glioblastoma cells with a selective HDAC6 inhibitor, tubastatin A, to determine if the malignant phenotype may be reverted. The results demonstrated a notable increase in acetylated α‑tubulin levels in treated cells, which associated with downregulation of the sonic hedgehog pathway, and may hypothetically promote ciliogenesis in those cells. Treatment with tubastatin A also reduced glioblastoma clonogenicity and migration capacities, and accelerated temozolomide‑induced apoptosis. Finally, HDAC6 inhibition decreased the expression of mesenchymal markers, contributing to reverse epithelial‑mesenchymal transition in glioblastoma cells.

Combination therapy to checkmate Glioblastoma: clinical challenges and advances

Combination therapy is increasingly becoming the cornerstone of current day antitumor therapy. Glioblastoma multiforme is an aggressive brain tumor with a dismal median survival post diagnosis and a high rate of disease recurrence. The poor prognosis can be attributed to unique treatment limitations, which include the infiltrative nature of tumor cells, failure of anti-glioma drugs to cross the blood-brain barrier, tumor heterogeneity and the highly metastatic and angiogenic nature of the tumor making cells resistant to chemotherapy. Combination therapy approach is being developed against glioblastoma with new innovative combination drug regimens being tested in preclinical and clinical trials. In this review, we discuss the pathophysiology of glioblastoma, diagnostic markers, therapeutic targeting strategies, current treatment limitations, novel combination therapies in the context of current treatment options and the ongoing clinical trials for glioblastoma therapy.

Role and inhibition of GLI1 protein in cancer

GLI1 is a transcriptional regulator involved in the development of different types of cancer. GLI1 transcriptional activity is regulated within the Hedgehog pathway (canonical activity), but can also be controlled independently (non-canonical activity) in the context of other signaling pathways. Experimental evidences show GLI1 involvement in both small- and non–small-cell lung cancers. Direct inhibition of the protein, in combination with other chemotherapeutic agents, represents a promising strategy for the treatment of different malignancies.

Omeprazole Inhibits Cell Proliferation and Induces G0/G1 Cell Cycle Arrest through Up-regulating miR-203a-3p Expression in Barrett's Esophagus Cells

Existing data suggest that proton pump inhibitors (PPIs), particularly omeprazole, have significant anti-tumor action in monotherapy and or combination chemotherapy. Hedgehog (Hh) signaling pathway represents a leading candidate as a molecular mediator of Barrett's esophagus (BE). Studies have indicated reduced miRNAs in BE progression, however, little is known about the latent anti-neoplasm effects of miRNAs in BE cells. Here, we investigated whether omeprazole could inhibit BE progression by regulating Hh pathway and explored the promising Hh-targeted miRNAs in BE cells. We conducted qRT-PCR and immunoblotting assay to evaluate the effects of omeprazole on the expression of Hh signaling components and miR-203a-3p in CP-A and CP-B cells. The promising target genes of miR-203a-3p were predicted by bioinformatics methods, and verified by luciferase assays and qRT-PCR. The effects of omeprazole on BE cell proliferation and cell cycle distribution were determined. The overexpression or silencing of miR-203a-3p was performed to test its anti-proliferative effects. Finally, rescue experiments that miR-203a-3p inhibitor alleviated the effects of omeprazole on decreasing the levels of Gli1 mRNA, protein and luciferase were performed. Mechanistic studies showed that omeprazole could inhibit the expression of Gli1 and the nuclear localization of Gli1. Moreover, we determined that omeprazole could selectively up-regulated the expression of miR-203a-3p, and Gli1 was a bona fide target of miR-203a-3p. miR-203a-3p inhibitor alleviated the suppressing effects of omeprazole on Gli1 luciferase activity, mRNA and protein level. The functional assay suggested that omeprazole could dose-dependently inhibit BE cell growth and induce cell cycle arrest in G0/G1 phase. Additionally, overexpression and silencing of miR-203a-3p in BE cells disrupted cell cycle progress, resulting in suppressing and accelerating cell proliferation, respectively. Taken together, these data provide a novel mechanism of potentially anti-neoplastic effects for omeprazole through modulation of miR-203a-3p expression and thus suppressing Hh/Gli1 signaling in BE cells.