Inhibition of TAZ contributes radiation-induced senescence and growth arrest in glioma cells

Exploring the potential anti-senescence effects of soybean-derived peptide Soymetide in mice hippocampal neurons via the Wnt/β-catenin pathway

Soybean-based foods enhance cognitive functions by influencing hippocampal mechanisms. These salutary effects have so far been attributed to isoflavones present in soybeans. Considering cellular senescence contributes to cognitive decline and that no specific soy-derived peptides are known for their potential to mitigate senescence, we examined the efficacy of a thirteen amino acid soy-derived peptide, Soymetide, on a doxorubicin-induced senescence mice model. Soymetide pretreatment lowered the senescence markers p53, p21 and p16, pro-inflammatory cytokines, and Senescence β-Galactosidase staining while enhancing the mature neuronal marker NeuN in the hippocampus. This anti-senescent effect was comparable with that of a well-known senolytic combination (dasatinib and quercetin). Research indicates that Wnt signaling influences cellular senescence, and our findings here demonstrate that doxorubicin decreased hippocampal Wnt3a, p-LRP6, Frizzled, Dishevelled, Axin1, and β-catenin levels and increased GSK-3β, while Soymetide mitigated these effects. Additionally, upon inhibition of the Wnt/β-catenin pathway, Soymetide's ability to reduce senescence markers and restore NeuN expression was reduced. We validated the anti-senescence impact on hippocampal neurons by co-immunostaining Wnt/β-catenin and senescence indicators alongside NeuN in mice and assessed it in primary hippocampal neurons. Further examining the neuronal survival and functions revealed that Soymetide blocked the doxorubicin-induced loss in Nissl-stained surviving neurons and learning-memory performances, measured by Y-Maze and Passive Avoidance tests, which Wnt/β-catenin inhibitors could counteract. In conclusion, our study identifies a novel Wnt/β-catenin-linked mechanism of doxorubicin-induced senescence in the hippocampal neurons and demonstrates Soymetide's effectiveness in reversing this process. Hence, this suggests Soymetide's potential therapeutic application in addressing cognitive decline associated with cellular aging.

Isoform Switching Regulates the Response to Ionizing Radiation Through SRSF1

PURPOSE

This study investigated how isoform switching affects the cellular response to ionizing radiation (IR), an understudied area despite its relevance to radiation therapy in cancer treatment. We aimed to identify changes in transcript isoform expression post-IR exposure and the proteins mediating these changes, with a focus on their potential to modulate radiosensitivity.

METHODS AND MATERIALS

Using RNA sequencing, we analyzed the B-cell lines derived from 10 healthy individuals at 3 timepoints, applying the mixture of isoforms algorithm to quantify alternative splicing. We examined RNA binding protein motifs within the sequences of IR-responsive isoforms and validated the serine/arginine-rich splicing factor 1 (SRSF1) as a predominant mediator through RNA immunoprecipitation. We further investigated the effects of SRSF1 on radiosensitivity by RNA interference and by analyzing publicly available data on patients with cancer.

RESULTS

We identified ∼1900 radiation-responsive alternatively spliced isoforms. Many isoforms were differentially expressed without changes in their overall gene expression. Over a third of these transcripts underwent exon skipping, while others used proximal last exons. These IR-responsive isoforms tended to be shorter transcripts missing vital domains for preventing apoptosis and promoting cell division but retaining those necessary for DNA repair. Our combined computational, genetic, and molecular analyses identified the proto-oncogene SRSF1 as a mediator of these radiation-induced isoform-switching events that promote apoptosis. After exposure to DNA double-strand break-inducing agents, SRSF1 expression decreased. A reduction in SRSF1 increased radiosensitivity in vitro and among patients with cancer.

CONCLUSIONS

We establish a pivotal role for isoform switching in the cellular response to IR and propose SRSF1 as a promising biomarker for assessing radiation therapy effectiveness.

Overexpression of Growth Differentiation Factor 15 in Glioblastoma Stem Cells Promotes Their Radioresistance

GSCs play an important role in GBM recurrence. Understanding the resistance mechanisms in these cells is therefore crucial for radiation therapy optimization. In this study, using patient-derived GSCs, we demonstrate that GDF15, a cytokine belonging to the TGF-β superfamily, is regulated by irradiation (IR) and the transcription factor WWTR1/TAZ. Blocking WWTR1/TAZ using specific siRNAs significantly reduces GDF15 basal expression and reverses the upregulation of this cytokine induced by IR. Furthermore, we demonstrate that GDF15 plays an important role in GSC radioresistance. Targeting GDF15 expression by siRNA in GSCs expressing high levels of GDF15 sensitizes the cells to IR. In addition, we also found that GDF15 expression is critical for GSC spheroid formation, as GDF15 knockdown significantly reduces the number of GSC neurospheres. This study suggests that GDF15 targeting in combination with radiotherapy may be a feasible approach in patients with GBM.

An untapped window of opportunity for glioma: targeting therapy-induced senescence prior to recurrence

High-grade gliomas are primary brain tumors that are incredibly refractory long-term to surgery and chemoradiation, with no proven durable salvage therapies for patients that have failed conventional treatments. Post-treatment, the latent glioma and its microenvironment are characterized by a senescent-like state of mitotic arrest and a senescence-associated secretory phenotype (SASP) induced by prior chemoradiation. Although senescence was once thought to be irreversible, recent evidence has demonstrated that cells may escape this state and re-enter the cell cycle, contributing to tumor recurrence. Moreover, senescent tumor cells could spur the growth of their non-senescent counterparts, thereby accelerating recurrence. In this review, we highlight emerging evidence supporting the use of senolytic agents to ablate latent, senescent-like cells that could contribute to tumor recurrence. We also discuss how senescent cell clearance can decrease the SASP within the tumor microenvironment thereby reducing tumor aggressiveness at recurrence. Finally, senolytics could improve the long-term sequelae of prior therapy on cognition and bone marrow function. We critically review the senolytic drugs currently under preclinical and clinical investigation and the potential challenges that may be associated with deploying senolytics against latent glioma. In conclusion, senescence in glioma and the microenvironment are critical and potential targets for delaying or preventing tumor recurrence and improving patient functional outcomes through senotherapeutics.

Radiation-Induced Cellular Senescence Reduces Susceptibility of Glioblastoma Cells to Oncolytic Vaccinia Virus

Glioblastoma (GBM) is a malignant brain cancer refractory to the current standard of care, prompting an extensive search for novel strategies to improve outcomes. One approach under investigation is oncolytic virus (OV) therapy in combination with radiotherapy. In addition to the direct cytocidal effects of radiotherapy, radiation induces cellular senescence in GBM cells. Senescent cells cease proliferation but remain viable and are implicated in promoting tumor progression. The interaction of viruses with senescent cells is nuanced; some viruses exploit the senescent state to their benefit, while others are hampered, indicating senescence-associated antiviral activity. It is unknown how radiation-induced cellular senescence may impact the oncolytic properties of OVs based on the vaccinia virus (VACV) that are used in combination with radiotherapy. To better understand this, we induced cellular senescence by treating GBM cells with radiation, and then evaluated the growth kinetics, infectivity, and cytotoxicity of an oncolytic VACV, ∆F4LΔJ2R, as well as wild-type VACV in irradiated senescence-enriched and non-irradiated human GBM cell lines. Our results show that both viruses display attenuated oncolytic activities in irradiated senescence-enriched GBM cell populations compared to non-irradiated controls. These findings indicate that radiation-induced cellular senescence is associated with antiviral activity and highlight important considerations for the combination of VACV-based oncolytic therapies with senescence-inducing agents such as radiotherapy.

Mechanical Properties of Glioblastoma: Perspectives for YAP/TAZ Signaling Pathway and Beyond

Glioblastoma is a highly aggressive brain tumor with a poor prognosis. Recent studies have suggested that mechanobiology, the study of how physical forces influence cellular behavior, plays an important role in glioblastoma progression. Several signaling pathways, molecules, and effectors, such as focal adhesions, stretch-activated ion channels, or membrane tension variations, have been studied in this regard. Also investigated are YAP/TAZ, downstream effectors of the Hippo pathway, which is a key regulator of cell proliferation and differentiation. In glioblastoma, YAP/TAZ have been shown to promote tumor growth and invasion by regulating genes involved in cell adhesion, migration, and extracellular matrix remodeling. YAP/TAZ can be activated by mechanical cues such as cell stiffness, matrix rigidity, and cell shape changes, which are all altered in the tumor microenvironment. Furthermore, YAP/TAZ have been shown to crosstalk with other signaling pathways, such as AKT, mTOR, and WNT, which are dysregulated in glioblastoma. Thus, understanding the role of mechanobiology and YAP/TAZ in glioblastoma progression could provide new insights into the development of novel therapeutic strategies. Targeting YAP/TAZ and mechanotransduction pathways in glioblastoma may offer a promising approach to treating this deadly disease.

The Molecular and Cellular Strategies of Glioblastoma and Non-Small-Cell Lung Cancer Cells Conferring Radioresistance

Ionizing radiation (IR) has been shown to play a crucial role in the treatment of glioblastoma (GBM; grade IV) and non-small-cell lung cancer (NSCLC). Nevertheless, recent studies have indicated that radiotherapy can offer only palliation owing to the radioresistance of GBM and NSCLC. Therefore, delineating the major radioresistance mechanisms may provide novel therapeutic approaches to sensitize these diseases to IR and improve patient outcomes. This review provides insights into the molecular and cellular mechanisms underlying GBM and NSCLC radioresistance, where it sheds light on the role played by cancer stem cells (CSCs), as well as discusses comprehensively how the cellular dormancy/non-proliferating state and polyploidy impact on their survival and relapse post-IR exposure.

Effect of mechanical forces on cellular response to radiation

While the cellular interactions and biochemical signaling has been investigated for long and showed to play a major role in the cell's fate, it is now also evident that mechanical forces continuously applied to the cells in their microenvironment are as important for tissue homeostasis. Mechanical cues are emerging as key regulators of cellular drug response and we aimed to demonstrate in this review that such effects should also be considered vital for the cellular response to radiation. In order to explore the mechanobiology of the radiation response, we reviewed the main mechanoreceptors and transducers, including integrin-mediated adhesion, YAP/TAZ pathways, Wnt/β-catenin signaling, ion channels and G protein-coupled receptors and showed their implication in the modulation of cellular radiosensitivity. We then discussed the current studies that investigated a direct effect of mechanical stress, including extracellular matrix stiffness, shear stress and mechanical strain, on radiation response of cancer and normal cells and showed through preliminary results that such stress effectively can alter cell response after irradiation. However, we also highlighted the limitations of these studies and emphasized some of the contradictory data, demonstrating that the effect of mechanical cues could involve complex interactions and potential crosstalk with numerous cellular processes also affected by irradiation. Overall, mechanical forces alter radiation response and although additional studies are required to deeply understand the underlying mechanisms, these effects should not be neglected in radiation research as they could reveal new fundamental knowledge for predicting radiosensitivity or understanding resistance to radiotherapy.

Ferroptosis in Glioma Immune Microenvironment: Opportunity and Challenge

Glioma is the most common intracranial malignant tumor in adults and the 5-year survival rate of glioma patients is extremely poor, even in patients who received Stupp treatment after diagnosis and this forces us to explore more efficient clinical strategies. At this time, immunotherapy shows great potential in a variety of tumor clinical treatments, however, its clinical effect in glioma is limited because of tumor immune privilege which was induced by the glioma immunosuppressive microenvironment, so remodeling the immunosuppressive microenvironment is a practical way to eliminate glioma immunotherapy resistance. Recently, increasing studies have confirmed that ferroptosis, a new form of cell death, plays an important role in tumor progression and immune microenvironment and the crosstalk between ferroptosis and tumor immune microenvironment attracts much attention. This work summarizes the progress studies of ferroptosis in the glioma immune microenvironment.

Early Therapeutic Interventions for Newly Diagnosed Glioblastoma: Rationale and Review of the Literature

PURPOSE OF REVIEW

Glioblastoma is the commonest primary brain cancer in adults whose outcomes are amongst the worst of any cancer. The current treatment pathway comprises surgery and postoperative chemoradiotherapy though unresectable diffusely infiltrative tumour cells remain untreated for several weeks post-diagnosis. Intratumoural heterogeneity combined with increased hypoxia in the postoperative tumour microenvironment potentially decreases the efficacy of adjuvant interventions and fails to prevent early postoperative regrowth, called rapid early progression (REP). In this review, we discuss the clinical implications and biological foundations of post-surgery REP. Subsequently, clinical interventions potentially targeting this phenomenon are reviewed systematically.

RECENT FINDINGS

Early interventions include early systemic chemotherapy, neoadjuvant immunotherapy, local therapies delivered during surgery (including Gliadel wafers, nanoparticles and stem cell therapy) and several radiotherapy techniques. We critically appraise and compare these strategies in terms of their efficacy, toxicity, challenges and potential to prolong survival. Finally, we discuss the most promising strategies that could benefit future glioblastoma patients. There is biological rationale to suggest that early interventions could improve the outcome of glioblastoma patients and they should be investigated in future trials.

The RNA binding protein QKI5 suppresses ovarian cancer via downregulating transcriptional coactivator TAZ

RNA-binding proteins (RBPs) are a set of proteins involved in many steps of post-transcriptional regulation to maintain cellular homeostasis. Ovarian cancer (OC) is the most deadly gynecological cancer, but the roles of RBPs in OC are not fully understood. Here, we reported that the RBP QKI5 was significantly negatively correlated with aggressive tumor stage and worse prognosis in serous OC patients. QKI5 could suppress the growth and metastasis of OC cells both in vitro and in vivo. Transcriptome analysis showed that QKI5 negatively regulated the expression of the transcriptional coactivator TAZ and its downstream targets (e.g., CTGF and CYR61). Mechanistically, QKI5 bound to TAZ mRNA and recruited EDC4, thus decreasing the stability of TAZ mRNA. Functionally, TAZ was involved in the QKI5-mediated tumor suppression of OC cells, and QKI5 expression was inversely correlated with TAZ, CTGF, and CYR61 expression in OC patients. Together, our study indicates that QKI5 plays a tumor-suppressive role and negatively regulates TAZ expression in OC.

LncRNA MIR4435-2HG functions as a ceRNA against miR-125a-5p and promotes neuroglioma development by upregulating TAZ

BACKGROUND

Expression of the TAZ gene is closely related to the prognosis of glioma patients. We hoped to find long noncoding RNAs (lncRNAs) related to TAZ and a new target for glioma treatment.

METHODS

TAZ-related genes were found by dual-luciferase reporter gene assay, and the correlation of each gene was analyzed by the Pearson method. Human glioma cell lines U87 MG and U251 and glioma rats were used for cytology assays, and the related genes were transfected. We conducted immunohistochemistry, RT-qPCR, Western blotting, CCK8 test, flow cytometry, transwell assays, clone formation analysis, and tumor weight measurements to verify the above relationship.

RESULTS

We found that miR-125a-5p was closely related to the TAZ gene, and the lncRNA MIR4435-2HG was closely related to miR-125a-5p. Both MIR4435-2HG-OE and TAZ increased the expression of the TAZ gene, activated the Wnt signaling pathway, inhibited apoptosis, and promoted migration and proliferation in glioma cells. Besides, it also increased the tumor volume of gliomas in a rat model subcutaneously inoculated with glioma cells. We also found miR-125a-5p could block the effect of MIR4435-2HG-OE and TAZ.

CONCLUSIONS

LncRNA MIR4435-2HG obstructs the functions of miR-125a-5p and promotes neuroglioma development by upregulating the TAZ gene.

LncRNA RBPMS-AS1 promotes NRGN transcription to enhance the radiosensitivity of glioblastoma through the microRNA-301a-3p/CAMTA1 axis

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RBPMS-AS1 and CAMTA1 are lowly expressed in GBM patients.

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RBPMS-AS1 and CAMTA1 enhance the radiosensitivity of GBM.

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miR-301a-3p diminishes the radiosensitivity of GBM.

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RBPMS-AS1 enhances CAMTA1 expression in GBM cells through sponging miR-301a-3p.

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CAMTA1 promotes NRGN transcription.

Objective

Glioblastoma (GBM) is the most frequent brain malignancy with high incidence, and long noncoding RNAs (lncRNAs) exerts functions in GBM. In this research, we focused on the capabilities of lncRNA RBPMS-AS1 in radiosensitivity of GBM.

Methods

RBPMS-AS1 and CAMTA1 expression levels were determined in GBM tissues and cells. StarBase v3.0 database was searched for predicting miRNAs that simultaneously bound to RBPMS-AS1 and CAMTA1. pcDNA3.1-RBPMS-AS1, pcDNA3.1-CAMTA1, miR-301a-3p mimic, or pcDNA3.1-RBPMS-AS1/pcDNA3.1-CAMTA1 and miR-301a-3p mimic were transfected into GBM cells to test radiosensitivity, cell proliferation and apoptosis. The interactions of miR-301a-3p with RBPMS-AS1 and CAMTA1, as well as CAMTA1 and NRGN, were confirmed. In vivo imaging technology was utilized to detect tumor growth in orthotopic xenograft tumors, and Ki67 expression was tested in intracranial tumors.

Results

RBPMS-AS1 and CAMTA1 levels were reduced in GBM tissues and cells. miR-301a-3p had a binding site with both RBPMS-AS1 and CAMTA1 and it was the most significantly-upregulated one. Upregulation of RBPMS-AS1 or CAMTA1 enhanced the radiosensitivity and cell apoptosis while suppressing proliferation of GBM cells. Conversely, miR-301a-3p overexpression diminished the radiosensitivity and cell apoptosis while inducing proliferation of GBM cells. Overexpression of RBPMS-AS1 or CAMTA1 reversed the effects of overexpressed miR-301a-3p in GBM cells. Mechanistically, RBPMS-AS1 enhanced CAMTA1 expression in GBM cells through sponging miR-301a-3p, and CAMTA1 promoted NRGN expression. In animal experiments, overexpressed RBPMS-AS1 inhibited tumor growth and the positive expression of Ki67 both before and after radiation therapy.

Conclusion

RBPMS-AS1 promotes NRGN transcription through the miR-301a-3p/CAMTA1 axis and enhances the radiosensitivity of GBM.

Elimination of Radiation-Induced Senescence in the Brain Tumor Microenvironment Attenuates Glioblastoma Recurrence

Glioblastomas (GBM) are routinely treated with ionizing radiation (IR) but inevitably recur and develop therapy resistance. During treatment, the tissue surrounding tumors is also irradiated. IR potently induces senescence, and senescent stromal cells can promote the growth of neighboring tumor cells by secreting factors that create a senescence-associated secretory phenotype (SASP). Here, we carried out transcriptomic and tumorigenicity analyses in irradiated mouse brains to elucidate how radiotherapy-induced senescence of non-neoplastic brain cells promotes tumor growth. Following cranial irradiation, widespread senescence in the brain occurred, with the astrocytic population being particularly susceptible. Irradiated brains showed an altered transcriptomic profile characterized by upregulation of CDKN1A (p21), a key enforcer of senescence, and several SASP factors, including HGF, the ligand of the receptor tyrosine kinase (RTK) Met. Preirradiation of mouse brains increased Met-driven growth and invasiveness of orthotopically implanted glioma cells. Importantly, irradiated p21^-/- mouse brains did not exhibit senescence and consequently failed to promote tumor growth. Senescent astrocytes secreted HGF to activate Met in glioma cells and to promote their migration and invasion in vitro, which could be blocked by HGF-neutralizing antibodies or the Met inhibitor crizotinib. Crizotinib also slowed the growth of glioma cells implanted in preirradiated brains. Treatment with the senolytic drug ABT-263 (navitoclax) selectively killed senescent astrocytes in vivo, significantly attenuating growth of glioma cells implanted in preirradiated brains. These results indicate that SASP factors in the irradiated tumor microenvironment drive GBM growth via RTK activation, underscoring the potential utility of adjuvant senolytic therapy for preventing GBM recurrence after radiotherapy. SIGNIFICANCE: This study uncovers mechanisms by which radiotherapy can promote GBM recurrence by inducing senescence in non-neoplastic brain cells, suggesting that senolytic therapy can blunt recurrent GBM growth and aggressiveness.

Novel Strategies for Nanoparticle-Based Radiosensitization in Glioblastoma

Radiotherapy (RT) is one of the cornerstones in the current treatment paradigm for glioblastoma (GBM). However, little has changed in the management of GBM since the establishment of the current protocol in 2005, and the prognosis remains grim. Radioresistance is one of the hallmarks for treatment failure, and different therapeutic strategies are aimed at overcoming it. Among these strategies, nanomedicine has advantages over conventional tumor therapeutics, including improvements in drug delivery and enhanced antitumor properties. Radiosensitizing strategies using nanoparticles (NP) are actively under study and hold promise to improve the treatment response. We aim to describe the basis of nanomedicine for GBM treatment, current evidence in radiosensitization efforts using nanoparticles, and novel strategies, such as preoperative radiation, that could be synergized with nanoradiosensitizers.

Emerging roles for the YAP/TAZ transcriptional regulators in brain tumour pathology and targeting options

The transcriptional co-activators Yes-associated protein 1/transcriptional co-activator with PDZ-binding motif (YAP/TAZ) have emerged as significant regulators of a wide variety of cellular and organ functions with impact in early embryonic development, especially during the expansion of the neural progenitor cell pool. YAP/TAZ signalling regulates organ size development, tissue homeostasis, wound healing and angiogenesis by participating in a complex network of various pathways. However, recent evidence suggests an association of these physiologic regulatory effects of YAP/TAZ with pro-oncogenic activities. Herein, we discuss the physiological functions of YAP/TAZ as well as the extensive network of signalling pathways that control their expression and activity, leading to brain tumour development and progression. Furthermore, we describe current targeting approaches and drug options including direct YAP/TAZ and YAP-TEA domain transcription factor (TEAD) interaction inhibitors, G-protein coupled receptors (GPCR) signalling modulators and kinase inhibitors, which may be used to successfully attack YAP/TAZ-dependent tumours.

The Paradoxical Role of Cellular Senescence in Cancer

Cellular senescence occurs in proliferating cells as a consequence of various triggers including telomere shortening, DNA damage, and inappropriate expression of oncogenes. The senescent state is accompanied by failure to reenter the cell cycle under mitotic stimulation, resistance to cell death and enhanced secretory phenotype. A growing number of studies have convincingly demonstrated a paradoxical role for spontaneous senescence and therapy-induced senescence (TIS), that senescence may involve both cancer prevention and cancer aggressiveness. Cellular senescence was initially described as a physiological suppressor mechanism of tumor cells, because cancer development requires cell proliferation. However, there is growing evidence that senescent cells may contribute to oncogenesis, partly in a senescence-associated secretory phenotype (SASP)-dependent manner. On the one hand, SASP prevents cell division and promotes immune clearance of damaged cells, thereby avoiding tumor development. On the other hand, SASP contributes to tumor progression and relapse through creating an immunosuppressive environment. In this review, we performed a review to summarize both bright and dark sides of senescence in cancer, and the strategies to handle senescence in cancer therapy were also discussed.

Genome-wide CRISPR/Cas9 screening identifies CARHSP1 responsible for radiation resistance in glioblastoma

Glioblastomas (GBM) is the most common primary malignant brain tumor, and radiotherapy plays a critical role in its therapeutic management. Unfortunately, the development of radioresistance is universal. Here, we identified calcium-regulated heat-stable protein 1 (CARHSP1) as a critical driver for radioresistance utilizing genome-wide CRISPR activation screening. This is a protein with a cold-shock domain (CSD)-containing that is highly similar to cold-shock proteins. CARHSP1 mRNA level was upregulated in irradiation-resistant GBM cells and knockdown of CARHSP1 sensitized GBM cells to radiotherapy. The high expression of CARHSP1 upon radiation might mediate radioresistance by activating the inflammatory signaling pathway. More importantly, patients with high levels of CARHSP1 had poorer survival when treated with radiotherapy. Collectively, our findings suggested that targeting the CARHSP1/TNF-α inflammatory signaling activation induced by radiotherapy might directly affect radioresistance and present an attractive therapeutic target for GBM, particularly for patients with high levels of CARHSP1.

Radiation-induced YAP activation confers glioma radioresistance via promoting FGF2 transcription and DNA damage repair

Although radiotherapy is a well-known effective non-surgical treatment for malignant gliomas, the therapeutic efficacy is severely limited due to the radioresistance of tumor cells. Previously, we demonstrated that Yes-associated protein (YAP) promotes glioma malignant progression. However, whether YAP plays a role in radioresistance and its potential value in cancer treatment are still unclear. In this study, we found that high YAP expression is associated with poor prognosis in malignant glioma patients undergoing radiotherapy. Research in immortalized cell lines and primary cells from GBM patients revealed that YAP exhibited a radioresistant effect on gliomas via promoting DNA damage repair. Mechanistically, after radiation, YAP was translocated into the nucleus, where it promoted the expression and secretion of FGF2, leading to MAPK-ERK pathway activation. FGF2 is a novel target gene of YAP. Inhibition of YAP-FGF2-MAPK signaling sensitizes gliomas to radiotherapy and prolongs the survival of intracranial cell-derived and patient-derived xenograft models. These results suggest that YAP-FGF2-MAPK is a key mechanism of radioresistance and is an actionable target for improving radiotherapy efficacy.

B7-H3 suppresses doxorubicin-induced senescence-like growth arrest in colorectal cancer through the AKT/TM4SF1/SIRT1 pathway

Emerging evidence suggests that cellular senescence induced by chemotherapy has been recognized as a new weapon for cancer therapy. This study aimed to research novel functions of B7-H3 in cellular senescence induced by a low dose of doxorubicin (DOX) in colorectal cancer (CRC). Here, our results demonstrated that B7-H3 knockdown promoted, while B7-H3 overexpression inhibited, DOX-induced cellular senescence. B7-H3 knockdown dramatically enhanced the growth arrest of CRC cells after low-dose DOX treatment, but B7-H3 overexpression had the opposite effect. By RNA-seq analysis and western blot, we showed that B7-H3 prevented cellular senescence and growth arrest through the AKT/TM4SF1/SIRT1 pathway. Blocking the AKT/TM4SF1/SIRT1 pathway dramatically reversed B7-H3-induced resistance to cellular senescence. More importantly, B7-H3 inhibited DOX-induced cellular senescence of CRC cells in vivo. Therefore, targeting B7-H3 or the B7-H3/AKT/TM4SF1/SIRT1 pathway might be a new strategy for promoting cellular senescence-like growth arrest during drug treatment in CRC.

Hypoxia Transcriptomic Modifications Induced by Proton Irradiation in U87 Glioblastoma Multiforme Cell Line

In Glioblastoma Multiforme (GBM), hypoxia is associated with radioresistance and poor prognosis. Since standard GBM treatments are not always effective, new strategies are needed to overcome resistance to therapeutic treatments, including radiotherapy (RT). Our study aims to shed light on the biomarker network involved in a hypoxic (0.2% oxygen) GBM cell line that is radioresistant after proton therapy (PT). For cultivating cells in acute hypoxia, GSI’s hypoxic chambers were used. Cells were irradiated in the middle of a spread-out Bragg peak with increasing PT doses to verify the greater radioresistance in hypoxic conditions. Whole-genome cDNA microarray gene expression analyses were performed for samples treated with 2 and 10 Gy to highlight biological processes activated in GBM following PT in the hypoxic condition. We describe cell survival response and significant deregulated pathways responsible for the cell death/survival balance and gene signatures linked to the PT/hypoxia configurations assayed. Highlighting the molecular pathways involved in GBM resistance following hypoxia and ionizing radiation (IR), this work could suggest new molecular targets, allowing the development of targeted drugs to be suggested in association with PT.

Wnt signaling contributes to withdrawal symptoms from opioid receptor activation induced by morphine exposure or chronic inflammation

Preventing and treating opioid dependence and withdrawal is a major clinical challenge, and the underlying mechanisms of opioid dependence and withdrawal remain elusive. We hypothesized that prolonged morphine exposure or chronic inflammation-induced μ-opioid receptor activity serves as a severe stress that elicits neuronal alterations and recapitulates events during development. Here, we report that Wnt signaling, which is important in developmental processes of the nervous system, plays a critical role in withdrawal symptoms from opioid receptor activation in mice. Repeated exposures of morphine or peripheral inflammation produced by intraplantar injection of complete Freund's adjuvant significantly increase the expression of Wnt5b in the primary sensory neurons in dorsal root ganglion (DRG). Accumulated Wnt5b in DRG neurons quickly transmits to the spinal cord dorsal horn (DH) after naloxone treatment. In the DH, Wnt5b, acts through the atypical Wnt-Ryk receptor and alternative Wnt-YAP/TAZ signaling pathways, contributing to the naloxone-precipitated opioid withdrawal-like behavioral symptoms and hyperalgesia. Inhibition of Wnt synthesis and blockage of Wnt signaling pathways greatly suppress the behavioral and neurochemical alterations after naloxone-precipitated withdrawal. These findings reveal a critical mechanism underlying naloxone-precipitated opioid withdrawal, suggesting that targeting Wnt5b synthesis in DRG neurons and Wnt signaling in DH may be an effective approach for prevention and treatment of opioid withdrawal syndromes, as well as the transition from acute to chronic pain.

Hippo Signaling Pathway in Gliomas

The Hippo signaling pathway is a highly conserved pathway involved in tissue development and regeneration that controls organ size through the regulation of cell proliferation and apoptosis. The core Hippo pathway is composed of a block of kinases, MST1/2 (Mammalian STE20-like protein kinase 1/2) and LATS1/2 (Large tumor suppressor 1/2), which inhibits nuclear translocation of YAP/TAZ (Yes-Associated Protein 1/Transcriptional co-activator with PDZ-binding motif) and its downstream association with the TEAD (TEA domain) family of transcription factors. This pathway was recently shown to be involved in tumorigenesis and metastasis in several cancers such as lung, breast, or colorectal cancers but is still poorly investigated in brain tumors. Gliomas are the most common and the most lethal primary brain tumors representing about 80% of malignant central nervous system neoplasms. Despite intensive clinical protocol, the prognosis for patients remains very poor due to systematic relapse and treatment failure. Growing evidence demonstrating the role of Hippo signaling in cancer biology and the lack of efficient treatments for malignant gliomas support the idea that this pathway could represent a potential target paving the way for alternative therapeutics. Based on recent advances in the Hippo pathway deciphering, the main goal of this review is to highlight the role of this pathway in gliomas by a state-of-the-art synthesis.

CDK5 Activates Hippo Signaling to Confer Resistance to Radiation Therapy Via Upregulating TAZ in Lung Cancer

PURPOSE

Tumor resistance to radiation therapy is a therapeutic challenge in the treatment of patients with non-small cell lung cancer. Cyclin-dependent kinase 5 (CDK5) has been proposed to participate in cell proliferation, migration and invasion, drug resistance, and immune evasion. However, the functions and regulatory mechanisms of CDK5 in lung cancer radioresistance have not been investigated.

METHODS AND MATERIALS

DNA damage response and repair were measured by neutral comet assay and γ-H2AX and Rad51 foci staining. The biological functions of CDK5 in lung cancer radioresistance were investigated with clonogenic survival assays and xenograft tumor models. Small interfering RNAs and short hairpin RNAs were used to knock down CDK5 in A549 and H1299 cells. The effects of CDK5 depletion on the tumorigenic behaviors of lung cancer cells were evaluated in vitro and in vivo. Gene expression was examined by RNA-seq and quantitative real-time polymerase chain reaction.

RESULTS

We report that CDK5 depletion impairs lung cancer progression and radioresistance in vitro and in vivo. Mechanistically, we identify TAZ, a component of the Hippo pathway, as a critical downstream effector of CDK5. Loss of CDK5 downregulates TAZ expression and attenuates Hippo signaling activation. Importantly, we provide evidence that TAZ is the major effector mediating the biological functions of CDK5 in lung cancer.

CONCLUSIONS

These results illustrate that CDK5 activates Hippo signaling via TAZ to participate in tumorigenesis and radioresistance, suggesting that CDK5 may be a promising radiosensitization target for the treatment of lung cancer.

Key Regulatory miRNAs and their Interplay with Mechanosensing and Mechanotransduction Signaling Pathways in Breast Cancer Progression

According to the WHO, breast cancer is the most common cancer in women worldwide. Identification of underlying mechanisms in breast cancer progression is the main concerns of researches. The mechanical forces within the tumor microenvironment, in addition to biochemical stimuli such as different growth factors and cytokines, activate signaling cascades, resulting in various changes in cancer cell physiology. Cancer cell proliferation, invasiveness, migration, and, even, resistance to cancer therapeutic agents are changed due to activation of mechanotransduction signaling. The mechanotransduction signaling is frequently dysregulated in breast cancer, indicating its important role in cancer cell features. So far, a variety of experimental investigations have been conducted to determine the main regulators of the mechanotransduction signaling. Currently, the role of miRNAs has been well-defined in the cancer process through advances in molecular-based approaches. miRNAs are small groups of RNAs (∼22 nucleotides) that contribute to various biological events in cells. The central role of miRNAs in the regulation of various mediators involved in the mechanotransduction signaling has been well clarified over the last decade. Unbalanced expression of miRNAs is associated with different pathologic conditions. Overexpression and downregulation of certain miRNAs were found to be along with dysregulation of mechanotransduction signaling effectors. This study aimed to critically review the role of miRNAs in the regulation of mediators involved in the mechanosensing pathways and clarify how the cross-talk between miRNAs and their targets affect the cell behavior and physiology of breast cancer cells.

A Small-Molecule Tankyrase Inhibitor Reduces Glioma Stem Cell Proliferation and Sphere Formation

Evidence suggests that the growth and therapeutic resistance of glioblastoma (GBM) may be enabled by a population of glioma stem cells (GSCs) that are regulated by typical stem cell pathways, including the WNT/β-catenin signaling pathway. We wanted to explore the effect of treating GSCs with a small-molecule inhibitor of tankyrase, G007-LK, which has been shown to be a potent modulator of the WNT/β-catenin and Hippo pathways in colon cancer. Four primary GSC cultures and two primary adult neural stem cell cultures were treated with G007-LK and subsequently evaluated through the measurement of growth characteristics, as well as the expression of WNT/β-catenin and Hippo signaling pathway-related proteins and genes. Treatment with G007-LK decreased in vitro proliferation and sphere formation in all four primary GSC cultures in a dose-dependent manner. G007-LK treatment altered the expression of key downstream WNT/β-catenin and Hippo signaling pathway-related proteins and genes. Finally, cotreatment with the established GBM chemotherapeutic compound temozolomide (TMZ) led to an additive reduction in sphere formation, suggesting that WNT/β-catenin signaling may contribute to TMZ resistance. These observations suggest that tankyrase inhibition may serve as a supplement to current GBM therapy, although more work is needed to determine the exact downstream mechanisms involved.

TRIB3 confers glioma cell stemness via interacting with β-catenin

Here, we aim to explore whether tribbles pseudokinase 3 (TRIB3) enhances glioma cell stemness. TRIB3 was overexpressed in glioma tissues and cell-formed spheres, positively correlated with the size and grade. Additionally, TRIB3 expression displayed a negative correlation with the overall survival rate of glioma patients. Moreover, TRIB3 knockdown reduced the stemness of nonadherent spheres, evident by the decreased sphere-forming ability, stemness master expression, and ALDH1 activity, while TRIB3 overexpression enhanced the stemness of adherent cells, which was rescued by β-catenin knockdown. Mechanistically, TRIB3 activated β-catenin signaling via physically interacting with β-catenin. This study suggests that the TRIB3-β-catenin interaction is responsible for glioma cell stemness.

TRIB3 confers radiotherapy resistance in esophageal squamous cell carcinoma by stabilizing TAZ

Radioresistance becomes the major obstacle to reduce tumor recurrence and improve prognosis in the treatment of esophageal squamous cell carcinoma (ESCC). Thus new strategies for radioresistant ESCC are urgently needed. Herein, we reported that tribbles pseudokinase 3 (TRIB3) serves as a key regulator of radioresistance in ESCC. TRIB3 is overexpressed in ESCC tissues and cell lines. High expression of TRIB3 significantly correlates with poor radiotherapy response and prognosis in ESCC patients. Upregulation of TRIB3 in ESCC cells conferred radioresistance in vitro and in vivo by interacting with TAZ thus impeding β-TrCP-mediated TAZ ubiquitination and degradation. Conversely, silencing TRIB3 sensitized ESCC cells to ionizing radiation. More importantly, TRIB3 was significantly correlated with TAZ activation in ESCC biopsies, and patients with high expression of both TRIB3 and TAZ suffered the worst radiotherapy response and survival. Our study uncovers the critical mechanism of ESCC resistance to radiotherapy, and provides a new pharmacological opportunity for developing a mechanism-based strategy to eliminate radioresistant ESCC in clinical practice.

Smoothened Promotes Glioblastoma Radiation Resistance Via Activating USP3-Mediated Claspin Deubiquitination

PURPOSE

Glioblastoma (GBM) is one of the most aggressive and lethal cancer types in humans. The standard treatment approach is surgery followed by chemoradiation. However, the molecular mechanisms of innate tumor radioresistance remain poorly understood.

EXPERIMENTAL DESIGN

We tested the expression of Smoothened (Smo) in primary and recurrent GBM tissues and cells. Then, we determined radiation effectiveness against primary and recurrent GBM cells. Lastly, the functional role of Smo in GBM radioresistance was further confirmed by in vitro and in vivo experiments.

RESULTS

We reported that Smo was significantly upregulated in recurrent GBM cell lines and tumor tissues following radiation treatment. Higher Smo expression indicated poor prognosis of GBM patients after radiation treatment. Smo had radioresistance effects in both GBM cells and human tumor xenografts. The mechanisms underlying these effects involved the attenuation of DNA damage repair caused by IR. Importantly, we found that the effect of Smo on radioresistance was mediated by Claspin polyubiquitination and proteasomal degradation, leading to the regulation of ATR-Chk1 signaling. Moreover, we found that Smo reduced Claspin polyubiquitination and proteasomal degradation by promoting USP3 transcription. Furthermore, we demonstrated that the Smo inhibitor GDC-0449 induced radiosensitivity to GBM.

CONCLUSIONS

These data suggest that Smo confers radiation resistance in GBM by promoting USP3 transcription, leading to the activation of Claspin-dependent ATR-Chk1 signaling. These findings identify a potential mechanism of GBM resistance to radiation and suggest a potential therapeutic target for radiation resistance in GBM.

Molecular-Level Interactions between Engineered Materials and Cells

Various recent experimental observations indicate that growing cells on engineered materials can alter their physiology, function, and fate. This finding suggests that better molecular-level understanding of the interactions between cells and materials may guide the design and construction of sophisticated artificial substrates, potentially enabling control of cells for use in various biomedical applications. In this review, we introduce recent research results that shed light on molecular events and mechanisms involved in the interactions between cells and materials. We discuss the development of materials with distinct physical, chemical, and biological features, cellular sensing of the engineered materials, transfer of the sensing information to the cell nucleus, subsequent changes in physical and chemical states of genomic DNA, and finally the resulting cellular behavior changes. Ongoing efforts to advance materials engineering and the cell-material interface will eventually expand the cell-based applications in therapies and tissue regenerations.

Role of Hippo/YAP signaling in irradiation-induced glioma cell apoptosis

Background

Although Hippo/Yes-associated protein (YAP) signaling plays crucial roles in radiation sensitivity and resistance of multiple kinds of cancers, its role in the radiation sensitivity of glioma cells remains unclear. The present study aimed to reveal Hippo/YAP role in the radiation sensitivity of glioma cells.

Methods

Glioma U251 cells were administrated with different doses of irradiation. Cell Counting Kit-8 (CCK-8) and flow cytometry assays were used to assess cell viability and apoptosis. Co-immunoprecipitation (co-IP) assay was used to assess the interactions between proteins.

Results

The results showed that irradiation exposure significantly inhibited cell viability and induced cell apoptosis in a dose-dependent manner, as well as decreased YAP1 expression via enhancing RCHY1-mediated YAP1 protein degradation. In addition, we observed that downregulation of YAP1 or RCHY1 weakened the role of irradiation exposure in cell viability inhibition and apoptosis promotion.

Conclusion

Collectively, this study emphasizes the vital role of Hippo/YAP signaling in radiation sensitivity of glioma, that RCHY1-mediated YAP1 protein downregulation is a main mechanism accounting for radiation-induced glioma cell apoptosis. Our study may enrich the theoretical basis of Hippo/YAP signaling as a new target for improving radiation sensitivity in glioma.

Targeting cell surface GRP78 enhances pancreatic cancer radiosensitivity through YAP/TAZ protein signaling

Ionizing radiation (IR) can promote migration and invasion of cancer cells, but the basis for this phenomenon has not been fully elucidated. IR increases expression of glucose-regulated protein 78kDa (GRP78) on the surface of cancer cells (CS-GRP78), and this up-regulation is associated with more aggressive behavior, radioresistance, and recurrence of cancer. Here, using various biochemical and immunological methods, including flow cytometry, cell proliferation and migration assays, Rho activation and quantitative RT-PCR assays, we investigated the mechanism by which CS-GRP78 contributes to radioresistance in pancreatic ductal adenocarcinoma (PDAC) cells. We found that activated α₂-Macroglobulin (α₂M*) a ligand of the CS-GRP78 receptor, induces formation of the AKT kinase (AKT)/DLC1 Rho-GTPase-activating protein (DLC1) complex and thereby increases Rho activation. Further, CS-GRP78 activated the transcriptional coactivators Yes-associated protein (YAP) and tafazzin (TAZ) in a Rho-dependent manner, promoting motility and invasiveness of PDAC cells. We observed that radiation-induced CS-GRP78 stimulates the nuclear accumulation of YAP/TAZ and increases YAP/TAZ target gene expressions. Remarkably, targeting CS-GRP78 with C38 monoclonal antibody (Mab) enhanced radiosensitivity and increased the efficacy of radiation therapy by curtailing PDAC cell motility and invasion. These findings reveal that CS-GRP78 acts upstream of YAP/TAZ signaling and promote migration and radiation-resistance in PDAC cells. We therefore conclude that, C38 Mab is a promising candidate for use in combination with radiation therapy to manage PDAC.

Harnessing Radiation Biology to Augment Immunotherapy for Glioblastoma

Glioblastoma is the most common adult primary brain tumor and carries a dismal prognosis. Radiation is a standard first-line therapy, typically deployed following maximal safe surgical debulking, when possible, in combination with cytotoxic chemotherapy. For other systemic cancers, standard of care is being transformed by immunotherapies, including checkpoint-blocking antibodies targeting CTLA-4 and PD-1/PD-L1, with potential for long-term remission. Ongoing studies are evaluating the role of immunotherapies for GBM. Despite dramatic responses in some cases, randomized trials to date have not met primary outcomes. Challenges have been attributed in part to the immunologically "cold" nature of glioblastoma relative to other malignancies successfully treated with immunotherapy. Radiation may serve as a mechanism to improve tumor immunogenicity. In this review, we critically evaluate current evidence regarding radiation as a synergistic facilitator of immunotherapies through modulation of both the innate and adaptive immune milieu. Although current preclinical data encourage efforts to harness synergistic biology between radiation and immunotherapy, several practical and scientific challenges remain. Moreover, insights from radiation biology may unveil additional novel opportunities to help mobilize immunity against GBM.