PTEN status mediates 2ME2 anti-tumor efficacy in preclinical glioblastoma models: role of HIF1α suppression

Understanding the Significance of Hypoxia-Inducible Factors (HIFs) in Glioblastoma: A Systematic Review

BACKGROUND

The study aims to investigate the role of hypoxia-inducible factors (HIFs) in the development, progression, and therapeutic potential of glioblastomas.

METHODOLOGY

The study, following PRISMA guidelines, systematically examined hypoxia and HIFs in glioblastoma using MEDLINE (PubMed), Web of Science, and Scopus. A total of 104 relevant studies underwent data extraction.

RESULTS

Among the 104 studies, global contributions were diverse, with China leading at 23.1%. The most productive year was 2019, accounting for 11.5%. Hypoxia-inducible factor 1 alpha (HIF1α) was frequently studied, followed by hypoxia-inducible factor 2 alpha (HIF2α), osteopontin, and cavolin-1. Commonly associated factors and pathways include glucose transporter 1 (GLUT1) and glucose transporter 3 (GLUT3) receptors, vascular endothelial growth factor (VEGF), phosphoinositide 3-kinase (PI3K)-Akt-mechanistic target of rapamycin (mTOR) pathway, and reactive oxygen species (ROS). HIF expression correlates with various glioblastoma hallmarks, including progression, survival, neovascularization, glucose metabolism, migration, and invasion.

CONCLUSION

Overcoming challenges such as treatment resistance and the absence of biomarkers is critical for the effective integration of HIF-related therapies into the treatment of glioblastoma with the aim of optimizing patient outcomes.

Hypoxia effects on glioblastoma progression through YAP/TAZ pathway regulation

The resistance of glioblastomas (GBM) to standard therapies poses a clinical challenge with limited survival despite interventions. The tumor microenvironment (TME) orchestrates GBM progression, comprising stromal and immune cells and is characterized by extensive hypoxic regions. Hypoxia activates the hypoxia-inducible factor 1 alpha (HIF-1α) pathway, interacting with the Hippo pathway (YAP/TAZ) in crucial cellular processes. We discuss here the related signaling crosstalk between YAP/TAZ and regions of hypoxia in the TME with particular attention on the MST1/2 and LATS1/2-regulated YAP/TAZ activation, impacting cell proliferation, invasion, and stemness. Moreover, the hypoxia-YAP/TAZ axis influence on angiogenesis, stem cells, and metabolic regulators is defined. By reviewing extracellular matrix alterations activation of YAP/TAZ, modulation of signaling pathways we also discuss the significance of spatial constraints and epigenetic modifications contribution to GBM progression, with potential therapeutic targets in YAP/TAZ-mediated gene regulation. Comprehensive understanding of the hypoxia-Hippo pathway-TME interplay offers insights for novel therapeutic strategies, aiming to provide new directions for treatment.

[Effects of lentivirus-mediated RNA interference of HIF-1α and PTEN on oxygen-glucose deprivation injury in primary cultured rat neurons]

OBJECTIVE

To observe the effects of lentivirus-mediated RNA interference (RNAi) of hypoxia-inducible factor 1α (HIF-1α) and phosphatase and tensin homolog on chromosome ten (PTEN) on oxygen-glucose deprivation (OGD) injury in primary cultured rat neurons.

METHODS

Primary cultures of neonatal SD rat neurons were infected by lentiviral vectors carrying short hairpin RNA (shRNA) targeting HIF-1α or PTEN followed 4 days later by hypoxic exposure, and the control neurons were infected with the empty virus only with or without subsequent hypoxic exposure. Twenty-four hours after hypoxia, the interference efficiency was assessed with qRT-PCR, and lactate dehydrogenase (LDH) assay and AnnexinV-FITC/ PI assay were performed to detect neuronal damage and apoptosis. The expressions of the related proteins were determined with Western blotting.

RESULTS

Lentivirus-mediated RNAi effectively silenced the mRNA expression of the target genes. HIF-1α silencing obviously aggravated the hypoxia-induced damage and apoptosis of the neurons, enhanced the expression of PTEN protein and significantly lowered the expressions of p-PTEN, p-AKT, NR2A and VEGFa (P < 0.05). PTEN silencing significantly alleviated hypoxia-induced damage and apoptosis of the neurons and increased the cellular expressions of p-PTEN and p-AKT (P < 0.05) without obviously affecting the expressions of HIF-1α, NR2A or VEGFa (P>0.05).

CONCLUSION

An up-regulated expression of HIF-1α causes down-regulation of PTEN expression to protect primary cultured rat neurons against OGD injury.

Hypoxia: The Cornerstone of Glioblastoma

Glioblastoma is the most aggressive form of brain tumor in adults and is characterized by the presence of hypervascularization and necrosis, both caused by a hypoxic microenvironment. In this review, we highlight that hypoxia-induced factor 1 (HIF-1), the main factor activated by hypoxia, is an important driver of tumor progression in GB patients. HIF-1α is a transcription factor regulated by the presence or absence of O2. The expression of HIF-1 has been related to high-grade gliomas and aggressive tumor behavior. HIF-1 promotes tumor progression via the activation of angiogenesis, immunosuppression, and metabolic reprogramming, promoting cell invasion and survival. Moreover, in GB, HIF-1 is not solely modulated by oxygen but also by oncogenic signaling pathways, such as MAPK/ERK, p53, and PI3K/PTEN. Therefore, the inhibition of the hypoxia pathway could represent an important treatment alternative in a disease with very few therapy options. Here, we review the roles of HIF-1 in GB progression and the inhibitors that have been studied thus far, with the aim of shedding light on this devastating disease.

The multifaceted NF-kB: are there still prospects of its inhibition for clinical intervention in pediatric central nervous system tumors?

Despite advances in the understanding of the molecular mechanisms underlying the basic biology and pathogenesis of pediatric central nervous system (CNS) malignancies, patients still have an extremely unfavorable prognosis. Over the years, a plethora of natural and synthetic compounds has emerged for the pharmacologic intervention of the NF-kB pathway, one of the most frequently dysregulated signaling cascades in human cancer with key roles in cell growth, survival, and therapy resistance. Here, we provide a review about the state-of-the-art concerning the dysregulation of this hub transcription factor in the most prevalent pediatric CNS tumors: glioma, medulloblastoma, and ependymoma. Moreover, we compile the available literature on the anti-proliferative effects of varied NF-kB inhibitors acting alone or in combination with other therapies in vitro, in vivo, and clinical trials. As the wealth of basic research data continues to accumulate, recognizing NF-kB as a therapeutic target may provide important insights to treat these diseases, hopefully contributing to increase cure rates and lower side effects related to therapy.

Exosomal miR-1246 from glioma patient body fluids drives the differentiation and activation of myeloid-derived suppressor cells

Glioma is a heterogeneous cellular environment in which immune cells play critical roles in tumor progression. Myeloid-derived suppressor cells (MDSCs) contribute to the formation of the immunosuppressive microenvironment of glioma; however, how glioma cells interact with MDSCs and how this interaction affects the function of other immune cells are unclear. Glioma cells can systemically communicate with immune cells via the secretion of exosomes, which contain miRNAs. Leveraging miRNA sequencing of exosomes, we identified enrichment of miR-1246 in glioma-derived exosomes and exosomes isolated from the cerebrospinal fluid (CSF) of glioma patients. We demonstrated that miR-1246 drives the differentiation and activation of MDSCs in a dual specificity phosphatase 3 (DUSP3)/ERK-dependent manner. In addition, postoperative CSF exosomal miR-1246 expression was found to be associated with the glioma recurrence rate. Hypoxia, a well-recognized feature of the glioblastoma microenvironment, increased miR-1246 levels in glioma-derived exosomes by enhancing miR-1246 transcription and selective packaging via upregulation of POU class 5 homeobox 1 (POU5F1) and heterogeneous nuclear ribonucleoprotein A1 (hnRNPA1). Importantly, we identified a mechanism of 2-Methoxyestradiol, a microtubule inhibitor currently undergoing clinical trials for glioblastoma. 2-Methoxyestradiol suppresses MDSC activation by inhibiting hypoxia-driven exosomal miR-1246 expression in glioma cells and PD-L1 expression in MDSCs.

HIF-1 α may play a role in late pregnancy hypoxia-induced autism-like behaviors in offspring rats

Autism spectrum disorder (ASD) is a neurodevelopmental disorder that can be caused by various factors. The present study aimed to determine whether prenatal hypoxia can lead to ASD and the role of hypoxia-inducible factor-1α (HIF-1α) in this process. We constructed a prenatal hypoxia model of pregnant rats by piping nitrogen and oxygen mixed gas, with an oxygen concentration of 10 ± 0.5 %, into the self-made hypoxia chamber. Rats were subjected to different extents of hypoxia treatments at different points during pregnancy. The results showed that hypoxia for 6 h on the 17th gestation day is most likely to lead to autistic behavior in offspring rats, including social deficits, repetitive behaviors, and impaired learning and memory. The mRNA expression level of TNF-α also increased in hypoxia-induced autism group and valproic acid (VPA) group. Western blotting analysis showed increased levels of hypoxia inducible factor 1 alpha (HIF-1α) and decreased levels of phosphatase and tensin homolog (PTEN) in the hypoxic-induced autism group. Meanwhile, N-methyl d-aspartate receptor subtype 2 (NR2A) and glutamate ionotropic receptor AMPA type subunit 2 (GluR2) were upregulated in the hypoxic-induced autism group. HIF-1α might play a role in hypoxia-caused autism-like behavior and its regulatory effect is likely to be achieved by regulating synaptic plasticity.

2-methoxyestradiol sensitizes breast cancer cells to taxanes by targeting centrosomes

Centrosomes amplification is a hallmark of cancer. We hypothesize that 2-methoxyestradiol (2-ME) sensitizes breast cancer (BC) cells to taxanes by targeting amplified centrosomes. We assessed the extent by which 2-ME together with paclitaxel (PTX) induces centrosome alterations with subsequent mitotic catastrophe in different BC subtypes. 2-ME induced a significant reduction in PTX IC50 values in all cells tested ranging from 28-44% (P < 0.05). Treatment with both PTX and 2-ME significantly increased the number of misaligned metaphases compared to PTX alone (34%, 100% and 52% for MCF7, MDA-MB231 and SUM149, respectively; P < 0.05). The number of cells with multipolar spindle formation was significantly increased (81%, 220% and 285% for MCF7, MDA-MB231 and SUM 149, respectively; P < 0.05). PTX and 2-ME treatment significantly increased interphase declustering in cancer cells (56% for MCF7, 208% for MDA-MB231 and 218% for SUM149, respectively; P < 0.05) and metaphase declustering (1.4-fold, 1.56-fold and 2.48-fold increase for MCF7, MDA-MB231 and SUM149, respectively; P < 0.05). This report is the first to document centrosome declustering as a mechanism of action of 2-ME and provides a potential approach for reducing taxane toxicity in cancer treated patients.

HIF-1 in cancer therapy: two decade long story of a transcription factor

BACKGROUND

Oxygen (O₂) homeostasis is an indispensable requirement of eukaryotes. O₂ concentration in cellular milieu is defined as normoxia (∼21% O₂), physoxia (∼1-13% O₂) or hypoxia (∼0.1-1% O₂). Hypoxia, a striking micro-environmental feature in tumorigenesis, is countered by tumor cells via induction of O₂ governed transcription factor, hypoxia inducible factor-1 (HIF-1). Post discovery, HIF-1 has emerged as a promising anticancer therapeutic target during the last two decades. Recent reports have highlighted that enhanced levels of HIF-1 correlate with tumor metastasis leading to poor patient prognosis.

MATERIAL AND METHODS

A systematic search in PubMed and SciFinder for the literature on HIF-1 biology and therapeutic importance in cancer was carried out.

RESULTS

This review highlights the initial description as well as the recent insights into HIF-1 biology and regulation. We have focused on emerging data regarding varied classes of HIF-1 target genes affecting various levels of crosstalk among tumorigenic pathways. We have emphasized on the fact that HIF-1 acts as a networking hub coordinating activities of multiple signaling molecules influencing tumorigenesis. Emerging evidences indicate role of many HIF-induced proteomic and genomic alterations in malignant progression by mediating a myriad of genes stimulating angiogenesis, anaerobic metabolism and survival of cancer cells in O₂-deficient microenvironment.

CONCLUSIONS

Better understanding of the crucial role of HIF-1 in carcinogenesis could offer promising new avenues to researchers and aid in elucidating various open issues regarding the use of HIF-1 as an anticancer therapeutic target. In spite of large efforts in this field, many questions still remain unanswered. Hence, future investigations are necessary to devise, assess and refine methods for translating previous research efforts into novel clinical practices in cancer treatment.

Inhibition of proliferation and invasion in 2D and 3D models by 2-methoxyestradiol in human melanoma cells

Despite the recent advances in the clinical management of melanoma, there remains a need for new pharmacological approaches to treat this cancer. 2-methoxyestradiol (2ME) is a metabolite of estrogen that has shown anti-tumor effects in many cancer types. In this study we show that 2ME treatment leads to growth inhibition in melanoma cells, an effect associated with entry into senescence, decreased pRb and Cyclin B1 expression, increased p21/Cip1 expression and G2/M cell cycle arrest. 2ME treatment also inhibits melanoma cell growth in colony formation assay, including cell lines with acquired resistance to BRAF and BRAF+MEK inhibitors. We further show that 2ME is effective against melanoma with different BRAF and NRAS mutational status. Moreover, 2ME induced the retraction of cytoplasmic projections in a 3D spheroid model and significantly decreased cell proliferation in a 3D skin reconstruct model. Together our studies bring new insights into the mechanism of action of 2ME allowing melanoma targeted therapy to be further refined. Continued progress in this area is expected to lead to improved anti-cancer treatments and the development of new and more effective clinical analogues.

2-Methoxyestradiol-Mediated Induction of Frzb Contributes to Cell Death and Autophagy in MG63 Osteosarcoma Cells

Osteosarcoma is a bone tumor that mainly affects children and adolescents. Although its pathogenesis is still not fully understood, activation of Wnt signaling has been implicated in the development and metastasis of osteosarcoma. In this report, we have investigated the effect of the anti-tumor compound, 2-methoxyestradiol (2-ME) on Wnt antagonist frizzled-related protein b (Frzb), also known as secreted frizzled-related protein (sFRP)3 in human osteosarcoma (MG63) cells. Our results show that 2-ME treatment induces Frzb gene promoter activity, and increases Frzb mRNA and protein levels in osteosarcoma cells. In addition, 2-ME treatment regulates downstream Wnt signaling, increasing the cytoplasmic levels of β-catenin, and blocking β-catenin-mediated Wnt activation in osteosarcoma cells. 2-ME-mediated induction of Frzb protein expression is specific to osteosarcoma cells, as it does not affect Frzb expression in normal primary human osteoblasts. Furthermore, 2-ME-induced apoptosis and autophagy are blocked in osteosarcoma cells transfected with Frzb siRNAs. Taken together, these studies demonstrate that Frzb protein plays an important role in 2-ME-mediated anti-tumor mechanisms in osteosarcoma cells. J. Cell. Biochem. 118: 1497-1504, 2017. © 2016 Wiley Periodicals, Inc.

Advances in the targeting of HIF-1α and future therapeutic strategies for glioblastoma multiforme (Review)

Cell metabolism can be reprogrammed by tissue hypoxia leading to cell transformation and glioblastoma multiforme (GBM) progression. In response to hypoxia, GBM cells are able to express a transcription factor called hypoxia inducible factor-1 (HIF-1). HIF-1 belongs to a family of heterodimeric proteins that includes HIF-1α and HIF-1β subunits. HIF-1α has been reported to play a pivotal role in GBM development and progression. In the present review, we discuss the role of HIF-1α in glucose uptake, cancer proliferation, cell mobility and chemoresistance in GBM. Evidence from previous studies indicates that HIF-1α regulates angiogenesis, metabolic and transcriptional signaling pathways. Examples of such are the EGFR, PI3K/Akt and MAPK/ERK pathways. It affects cell migration and invasion by regulating glucose metabolism and growth in GBM cells. The present review focuses on the strategies through which to target HIF-1α and the related downstream genes highlighting their regulatory roles in angiogenesis, apoptosis, migration and glucose metabolism for the development of future GBM therapeutics. Combined treatment with inhibitors of HIF-1α and glycolysis may enhance antitumor effects in clinical settings.

Anti-tumor effect of a novel PI3-kinase inhibitor, SF1126, in (12) V-Ha-Ras transgenic mouse glioma model

Background

Growth factor mediated activation of RAS-MAP-kinase and PI3-kinase-AKT pathways are critical for the pathogenesis of glioblastoma. The attenuation of PI3-kinase/AKT signaling will be effective in regulating the tumorigenic phenotypes of the glioma cells.

Methods

Glioma cells derived from the brain of the ¹² V-Ha-Ras transgenic mice were used to study the effect of PI-3 kinase inhibitor SF1126 on activation of AKT and ERK signaling, proliferation, vitronectin mediated migration and changes in the distribution of cortical actin on vitronectin in the glioma cells in vitro. The anti-tumor effects of SF1126 were also tested in vivo using pre-established tumors (subcutaneous injection of the glioma cells from ¹² V-Ha-Ras transgenic mice) in a mouse xenograft model.

Results

Our results demonstrate that treatment of LacZ+, GFAP + and PCNA + ¹² V-Ras Tg transformed astrocytes with SF1126 and LY294002 blocked the activation of AKT as well as EGF-induced phospho-ERK. Most notably, treatment of SF1126 blocked integrin-dependent migration in transwell and scratch assays and caused a significant change in the organization and distribution of cortical actin on vitronectin in the glioma cells. Moreover, SF1126 treatment inhibited in vitro proliferation of these cells and in vivo growth of pre-established subcutaneous tumors in a xenograft model.

Conclusion

The present study validate the potent anti-proliferative and anti-migratory activity of SF1126, in a V¹² Ras oncogene driven glioma model and suggest that this effect is mediated potentially through a combined attenuation of PI3-kinase and MAP-kinase signaling pathways.

NF-κB and STAT3 in glioblastoma: therapeutic targets coming of age

Since we last addressed the roles of NF-κB and JAK/STAT3 signaling in glioblastoma (GBM) 5 years ago, tremendous strides have been made in the understanding of these two pathways in glioma biology. Contributing to prosurvival mechanisms, cancer stem cell maintenance and treatment resistance, both NF-κB and STAT3 have been characterized as major drivers of GBM. In this review, we address general improvements in the molecular understanding of GBM, the structure of NF-κB and STAT3 signaling, the ways in which these pathways contribute to GBM and advances in preclinical and clinical targeting of these two signaling cascades.