Cyclopamine sensitizes glioblastoma cells to temozolomide treatment through Sonic hedgehog pathway

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.

Suppression of sonic hedgehog pathway-based proliferation in glioblastoma cells by small-size silver nanoparticles in vitro

Glioblastomas (GBs) are one of the most aggressive and invasive intracranial cancers. Recently, it has been postulated that, among other factors, the hedgehog (HH) pathway may be a key factor in this phenomenon. Moreover, it has been reported that small-size silver nanoparticles (AgNPs) are characterized by a high cytotoxic effect towards GBs. However, their effect on the sonic hedgehog (SHH) pathway has never been demonstrated in any cancer cells. Therefore, the aim of the present study was to evaluate the impact of the anti-proliferative properties of 5-nm AgNPs on the SHH pathway in the GB cell line (U-87MG) in vitro. The results showed a time- and dose-dependent decrease in the metabolic activity in the U-87MG cells treated with AgNPs, with IC50 reaching 30.41 and 21.16 µg/mL after 24 h and 48 h, respectively, followed by an increase in the intracellular reactive oxygen species (ROS) level. The co-treatment of the cells with AgNPs and Robotnikinin (SHH inhibitor) abolished and/or strengthened the effect of AgNPs, especially on the SHH mRNA levels and on the PCNA, PTCH1, Gli1, and SUFU protein levels. Interestingly, no changes in the level of ERK1/2, Akt, and SRC kinase protein expression were detected, suggesting a direct impact of AgNPs and/or ROS on the inhibition of the canonical SHH pathway. However, more studies are needed due to the increase in the mTOR protein expression after the treatment of the cells with AgNPs, as in the Robotnikinin treatment. In conclusion, small-size AgNPs are able to inhibit the proliferation of GB cells in vitro by suppressing the canonical SHH pathway.

Re-Sensitizing Cancer Stem Cells to Conventional Chemotherapy Agents

Cancer stem cells are found in many cancer types. They comprise a distinct subpopulation of cells within the tumor that exhibit properties of stem cells. They express a number of cell surface markers, such as CD133, CD44, ALDH, and EpCAM, as well as embryonic transcription factors Oct4, Nanog, and SOX2. CSCs are more resistant to conventional chemotherapy and can potentially drive tumor relapse. Therefore, it is essential to understand the molecular mechanisms that drive chemoresistance and to target them with specific therapy effectively. Highly conserved developmental signaling pathways such as Wnt, Hedgehog, and Notch are commonly reported to play a role in CSCs chemoresistance development. Studies show that particular pathway inhibitors combined with conventional therapy may re-establish sensitivity to the conventional therapy. Another significant contributor of chemoresistance is a specific tumor microenvironment. Surrounding stroma in the form of cancer-associated fibroblasts, macrophages, endothelial cells, and extracellular matrix components produce cytokines and other factors, thus creating a favorable environment and decreasing the cytotoxic effects of chemotherapy. Anti-stromal agents may potentially help to overcome these effects. Epigenetic changes and autophagy were also among the commonly reported mechanisms of chemoresistance. This review provides an overview of signaling pathway components involved in the development of chemoresistance of CSCs and gathers evidence from experimental studies in which CSCs can be re-sensitized to conventional chemotherapy agents across different cancer types.

Nanomedicines Targeting Glioma Stem Cells

Glioblastoma (GBM), classified as a grade IV glioma, is a rapidly growing, aggressive, and most commonly occurring tumor of the central nervous system. Despite the therapeutic advances, it carries an ominous prognosis, with a median survival of 14.6 months after diagnosis. Accumulating evidence suggests that cancer stem cells in GBM, termed glioma stem cells (GSCs), play a crucial role in tumor propagation, treatment resistance, and tumor recurrence. GSCs, possessing the capacity for self-renewal and multilineage differentiation, are responsible for tumor growth and heterogeneity, leading to primary obstacles to current cancer therapy. In this respect, increasing efforts have been devoted to the development of anti-GSC strategies based on targeting GSC surface markers, blockage of essential signaling pathways of GSCs, and manipulating the tumor microenvironment (GSC niches). In this review, we will discuss the research knowledge regarding GSC-based therapy and the underlying mechanisms for the treatment of GBM. Given the rapid progression in nanotechnology, innovative nanomedicines developed for GSC targeting will also be highlighted from the perspective of rationale, advantages, and limitations. The goal of this review is to provide broader understanding and key considerations toward the future direction of GSC-based nanotheranostics to fight against GBM.

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.

Current Opportunities for Targeting Dysregulated Neurodevelopmental Signaling Pathways in Glioblastoma

Glioblastoma (GBM) is the most common and highly lethal type of brain tumor, with poor survival despite advances in understanding its complexity. After current standard therapeutic treatment, including tumor resection, radiotherapy and concomitant chemotherapy with temozolomide, the median overall survival of patients with this type of tumor is less than 15 months. Thus, there is an urgent need for new insights into GBM molecular characteristics and progress in targeted therapy in order to improve clinical outcomes. The literature data revealed that a number of different signaling pathways are dysregulated in GBM. In this review, we intended to summarize and discuss current literature data and therapeutic modalities focused on targeting dysregulated signaling pathways in GBM. A better understanding of opportunities for targeting signaling pathways that influences malignant behavior of GBM cells might open the way for the development of novel GBM-targeted therapies.

Mir-326 potentiates radiosensitivity of cervical squamous cell carcinoma through downregulating SMO expression in the Hedgehog signaling pathway

BACKGROUND

Radiotherapy resistance affects the therapeutic effect of cervical squamous cell carcinoma (CSCC). Smoothened (Smo) is an anticancer target of the Hedgehog (Hh) pathway and its mutation is related to drug resistance.

OBJECTIVE

To explore the roles of miR-326 and Smoothened (SMO) on radiation resistance in patients with cervical carcinoma.

METHODS

Expression of miR-326 and SMO in cervical cancer tissue and radioresistant cell lines were analyzed. The radiation response with the expression of miR-326 was evaluated in tissue and cells. Bioinformatics analysis and literature review were performed to explore the target of miR-326. The regulation of miR-326 to SMO mRNA was verified through the dual-luciferase reporter assay.

RESULTS

Patients with poor radiation response have lower miR-326 and higher SMO expression. Upregulation of miR-326 decreased SMO expression and its downstream proteins but does not affect the proliferation of CSCC cells. The upregulation of miR-326 increased radiation sensitivity of the CSCC cell through downregulating SMO and its downstream proteins in the Hedgehog (Hh) signaling pathway.

CONCLUSIONS

miR-326 may predict the treatment response to radiation, and upregulating miR-326 may improve the treatment response to radiation.

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.