PARP-1 protein expression in glioblastoma multiforme

Forms of Non-Apoptotic Cell Death and Their Role in Gliomas-Presentation of the Current State of Knowledge

In addition to necrosis and apoptosis, the two forms of cell death that have been known for many decades, other non-apoptotic forms of cell death have been discovered, many of which also play a role in tumors. Starting with the description of autophagy more than 60 years ago, newer forms of cell death have become important for the biology of tumors, such as ferroptosis, pyroptosis, necroptosis, and paraptosis. In this review, all non-apoptotic and oncologically relevant forms of programmed cell death are presented, starting with their first descriptions, their molecular characteristics, and their role and their interactions in cell physiology and pathophysiology. Based on these descriptions, the current state of knowledge about their alterations and their role in gliomas will be presented. In addition, current efforts to therapeutically influence the molecular components of these forms of cell death will be discussed. Although research into their exact role in gliomas is still at a rather early stage, our review clarifies that all these non-apoptotic forms of cell death show significant alterations in gliomas and that important insight into understanding them has already been gained.

Non-apoptotic regulated cell death mediates reprogramming of the tumour immune microenvironment by macrophages

Tumour immune microenvironment (TIME) plays an indispensable role in tumour progression, and tumour-associated macrophages (TAMs) are the most abundant immune cells in TIME. Non-apoptotic regulated cell death (RCD) can avoid the influence of tumour apoptosis resistance on anti-tumour immune response. Specifically, autophagy, ferroptosis, pyroptosis and necroptosis mediate the crosstalk between TAMs and tumour cells in TIME, thus reprogram TIME and affect the progress of tumour. In addition, although some achievements have been made in immune checkpoint inhibitors (ICIs), there is still defect that ICIs are only effective for some people because non-apoptotic RCD can bypass the apoptosis resistance of tumour. As a result, ICIs combined with targeting non-apoptotic RCD may be a promising solution. In this paper, the basic molecular mechanism of non-apoptotic RCD, the way in which non-apoptotic RCD mediates crosstalk between TAMs and tumour cells to reprogram TIME, and the latest research progress in targeting non-apoptotic RCD and ICIs are reviewed.

Integrated single-cell sequencing, spatial transcriptome sequencing and bulk RNA sequencing highlights the molecular characteristics of parthanatos in gastric cancer

BACKGROUND

Parthanatos is a novel programmatic form of cell death based on DNA damage and PARP-1 dependency. Nevertheless, its specific role in the context of gastric cancer (GC) remains uncertain.

METHODS

In this study, we integrated multi-omics algorithms to investigate the molecular characteristics of parthanatos in GC. A series of bioinformatics algorithms were utilized to explore clinical heterogeneity of GC and further predict the clinical outcomes.

RESULTS

Firstly, we conducted a comprehensive analysis of the omics features of parthanatos in various human tumors, including genomic mutations, transcriptome expression, and prognostic relevance. We successfully identified 7 cell types within the GC microenvironment: myeloid cell, epithelial cell, T cell, stromal cell, proliferative cell, B cell, and NK cell. When compared to adjacent non-tumor tissues, single-cell sequencing results from GC tissues revealed elevated scores for the parthanatos pathway across multiple cell types. Spatial transcriptomics, for the first time, unveiled the spatial distribution characteristics of parthanatos signaling. GC patients with different parthanatos signals often exhibited distinct immune microenvironment and metabolic reprogramming features, leading to different clinical outcomes. The integration of parthanatos signaling and clinical indicators enabled the creation of novel survival curves that accurately assess patients' survival times and statuses.

CONCLUSIONS

In this study, the molecular characteristics of parthanatos' unicellular and spatial transcriptomics in GC were revealed for the first time. Our model based on parthanatos signals can be used to distinguish individual heterogeneity and predict clinical outcomes in patients with GC.

PARP1-targeted fluorescence molecular endoscopy as novel tool for early detection of esophageal dysplasia and adenocarcinoma

BACKGROUND

Esophageal cancer is one of the 10 most common cancers worldwide and its incidence is dramatically increasing. Despite some improvements, the current surveillance protocol with white light endoscopy and random untargeted biopsies collection (Seattle protocol) fails to diagnose dysplastic and cancerous lesions in up to 50% of patients. Therefore, new endoscopic imaging technologies in combination with tumor-specific molecular probes are needed to improve early detection. Herein, we investigated the use of the fluorescent Poly (ADP-ribose) Polymerase 1 (PARP1)-inhibitor PARPi-FL for early detection of dysplastic lesions in patient-derived organoids and transgenic mouse models, which closely mimic the transformation from non-malignant Barrett's Esophagus (BE) to invasive esophageal adenocarcinoma (EAC).

METHODS

We determined PARP1 expression via immunohistochemistry (IHC) in human biospecimens and mouse tissues. We also assessed PARPi-FL uptake in patient- and mouse-derived organoids. Following intravenous injection of 75 nmol PARPi-FL/mouse in L2-IL1B (n = 4) and L2-IL1B/IL8Tg mice (n = 12), we conducted fluorescence molecular endoscopy (FME) and/or imaged whole excised stomachs to assess PARPi-FL accumulation in dysplastic lesions. L2-IL1B/IL8Tg mice (n = 3) and wild-type (WT) mice (n = 2) without PARPi-FL injection served as controls. The imaging results were validated by confocal microscopy and IHC of excised tissues.

RESULTS

IHC on patient and murine tissue revealed similar patterns of increasing PARP1 expression in presence of dysplasia and cancer. In human and murine organoids, PARPi-FL localized to PARP1-expressing epithelial cell nuclei after 10 min of incubation. Injection of PARPi-FL in transgenic mouse models of BE resulted in the successful detection of lesions via FME, with a mean target-to-background ratio > 2 independently from the disease stage. The localization of PARPi-FL in the lesions was confirmed by imaging of the excised stomachs and confocal microscopy. Without PARPi-FL injection, identification of lesions via FME in transgenic mice was not possible.

CONCLUSION

PARPi-FL imaging is a promising approach for clinically needed improved detection of dysplastic and malignant EAC lesions in patients with BE. Since PARPi-FL is currently evaluated in a phase 2 clinical trial for oral cancer detection after topical application, clinical translation for early detection of dysplasia and EAC in BE patients via FME screening appears feasible.

Exploring beyond Common Cell Death Pathways in Oral Cancer: A Systematic Review

Oral squamous cell carcinoma (OSCC) is the most common and lethal type of head and neck cancer in the world. Variable response and acquisition of resistance to traditional therapies show that it is essential to develop novel strategies that can provide better outcomes for the patient. Understanding of cellular and molecular mechanisms of cell death control has increased rapidly in recent years. Activation of cell death pathways, such as the emerging forms of non-apoptotic programmed cell death, including ferroptosis, pyroptosis, necroptosis, NETosis, parthanatos, mitoptosis and paraptosis, may represent clinically relevant novel therapeutic opportunities. This systematic review summarizes the recently described forms of cell death in OSCC, highlighting their potential for informing diagnosis, prognosis and treatment. Original studies that explored any of the selected cell deaths in OSCC were included. Electronic search, study selection, data collection and risk of bias assessment tools were realized. The literature search was carried out in four databases, and the extracted data from 79 articles were categorized and grouped by type of cell death. Ferroptosis, pyroptosis, and necroptosis represented the main forms of cell death in the selected studies, with links to cancer immunity and inflammatory responses, progression and prognosis of OSCC. Harnessing the potential of these pathways may be useful in patient-specific prognosis and individualized therapy. We provide perspectives on how these different cell death types can be integrated to develop decision tools for diagnosis, prognosis, and treatment of OSCC.

Regulated cell death in glioma: promising targets for natural small-molecule compounds

Gliomas are prevalent malignant tumors in adults, which can be categorized as either localized or diffuse gliomas. Glioblastoma is the most aggressive and deadliest form of glioma. Currently, there is no complete cure, and the median survival time is less than one year. The main mechanism of regulated cell death involves organisms coordinating the elimination of damaged cells at risk of tumor transformation or cells hijacked by microorganisms for pathogen replication. This process includes apoptosis, necroptosis, autophagy, ferroptosis, pyroptosis, necrosis, parthanayosis, entosis, lysosome-dependent death, NETosis, oxiptosis, alkaliptosis, and disulfidaptosis. The main goal of clinical oncology is to develop therapies that promote the effective elimination of cancer cells by regulating cell death are the main goal of clinical oncology. Recently, scientists have utilized pertinent regulatory factors and natural small-molecule compounds to induce regulated cell death for the treatment of gliomas. By analyzing the PubMed and Web of Science databases, this paper reviews the research progress on the regulation of cell death and the role of natural small-molecule compounds in glioma. The aim is to provide help for the treatment of glioblastoma.

Arnicolide D Inhibits Oxidative Stress-induced Breast Cancer Cell Growth and Invasion through Apoptosis, Ferroptosis, and Parthanatos

BACKGROUND

Breast cancer is the most common malignant tumor in women, and its pathogenesis is very complicated. More and more studies have found that Traditional Chinese Medicine plays an important role in tumor prevention.

OBJECTIVE

To investigate the mechanism of arnicolide D isolated from Centipeda minima in breast cancer.

METHODS

Cell Counting Kit-8 (CCK-8), western blot, RT-qPCR, ELISA, flow cytometry, and Transwell were used to detect the effect of arnicolide D on the biological function of breast cancer cells.

RESULTS

Arnicolide D promoted reactive oxygen species (ROS) production and induced a decrease in mitochondrial membrane potential in breast cancer cells, thereby inhibiting cell viability and increasing lactate dehydrogenase (LDH) release. Arnicolide D activated the classical apoptosis pathway to induce cell apoptosis; it significantly promoted PARP-1 expression, enhanced the nuclear translocation of apoptosis-inducing factor (AIF), and reduced the expression of AIF in mitochondria, indicating that it can induce the occurrence of parthanatos in a ROS dependent manner. In addition, arnicolide D down-regulated glutathione peroxidase 4 (GPX4) expression and increased the accumulation of Fe2+ and malondialdehyde (MDA), thereby activating ferroptosis. Apoptosis inhibitor, ferroptosis inhibitor, PARP inhibitor, PARP-1 siRNA, AIF siRNA and GPX4 overexpression vector significantly attenuated the inhibitory effect of arnicolide D on cell viability and reduced LDH release, which indicates that arnicolide D inhibits breast cancer cell growth by inducing apoptosis, parthanatos and ferroptosis. Arnicolide D also reduced breast cancer cell invasion and inhibited the expression of matrix metallopeptidase (MMP)-2 and MMP-9.

CONCLUSION

Arnicolide D can activate a variety of cell death modes by inducing oxidative stress, thereby inhibiting the growth and invasion of breast cancer cells, indicating that arnicolide D has a good anti-tumor effect.

The cardiac glycoside ZINC253504760 induces parthanatos-type cell death and G2/M arrest via downregulation of MEK1/2 phosphorylation in leukemia cells

Overcoming multidrug resistance (MDR) represents a major obstacle in cancer chemotherapy. Cardiac glycosides (CGs) are efficient in the treatment of heart failure and recently emerged in a new role in the treatment of cancer. ZINC253504760, a synthetic cardenolide that is structurally similar to well-known GCs, digitoxin and digoxin, has not been investigated yet. This study aims to investigate the cytotoxicity of ZINC253504760 on MDR cell lines and its molecular mode of action for cancer treatment. Four drug-resistant cell lines (P-glycoprotein-, ABCB5-, and EGFR-overexpressing cells, and TP53-knockout cells) did not show cross-resistance to ZINC253504760 except BCRP-overexpressing cells. Transcriptomic profiling indicated that cell death and survival as well as cell cycle (G2/M damage) were the top cellular functions affected by ZINC253504760 in CCRF-CEM cells, while CDK1 was linked with the downregulation of MEK and ERK. With flow cytometry, ZINC253504760 induced G2/M phase arrest. Interestingly, ZINC253504760 induced a novel state-of-the-art mode of cell death (parthanatos) through PARP and PAR overexpression as shown by western blotting, apoptosis-inducing factor (AIF) translocation by immunofluorescence, DNA damage by comet assay, and mitochondrial membrane potential collapse by flow cytometry. These results were ROS-independent. Furthermore, ZINC253504760 is an ATP-competitive MEK inhibitor evidenced by its interaction with the MEK phosphorylation site as shown by molecular docking in silico and binding to recombinant MEK by microscale thermophoresis in vitro. To the best of our knowledge, this is the first time to describe a cardenolide that induces parthanatos in leukemia cells, which may help to improve efforts to overcome drug resistance in cancer. A cardiac glycoside compound ZINC253504760 displayed cytotoxicity against different multidrug-resistant cell lines. ZINC253504760 exhibited cytotoxicity in CCRF-CEM leukemia cells by predominantly inducing a new mode of cell death (parthanatos). ZINC253504760 downregulated MEK1/2 phosphorylation and further affected ERK activation, which induced G2/M phase arrest.

Cancer stem cells in brain tumors: From origin to clinical implications

Malignant brain tumors are highly heterogeneous tumors with a poor prognosis and a high morbidity and mortality rate in both children and adults. The cancer stem cell (CSC, also named tumor-initiating cell) model states that tumor growth is driven by a subset of CSCs. This model explains some of the clinical observations of brain tumors, including the almost unavoidable tumor recurrence after initial successful chemotherapy and/or radiotherapy and treatment resistance. Over the past two decades, strategies for the identification and characterization of brain CSCs have improved significantly, supporting the design of new diagnostic and therapeutic strategies for brain tumors. Relevant studies have unveiled novel characteristics of CSCs in the brain, including their heterogeneity and distinctive immunobiology, which have provided opportunities for new research directions and potential therapeutic approaches. In this review, we summarize the current knowledge of CSCs markers and stemness regulators in brain tumors. We also comprehensively describe the influence of the CSCs niche and tumor microenvironment on brain tumor stemness, including interactions between CSCs and the immune system, and discuss the potential application of CSCs in brain-based therapies for the treatment of brain tumors.

Trichosanthin Promotes Anti-Tumor Immunity through Mediating Chemokines and Granzyme B Secretion in Hepatocellular Carcinoma

Trichosanthin (TCS) is a type I ribosome-inactivating protein extracted from the tuberous root of the plant Trichosanthes. TCS shows promising potential in clinical drug abortion, anti-tumor and immunological regulation. However, the molecular mechanisms of its anti-tumor and immune regulation properties are still not well discovered. In the present study, we investigated the anti-tumor activity of TCS in hepatocellular carcinoma (HCC), both in vitro and in vivo. Both HCC cell lines and xenograft tumor tissues showed considerable growth inhibition after they were treated with TCS. TCS provoked caspase-mediated apoptosis in HCC cells and xenograft tumor tissues. The recruitment of CD8⁺ T cells to HCC tissues and the expression of chemokines, CCL2 and CCL22, were promoted upon TCS treatment. In addition, TCS induced an upregulation of Granzyme B (GrzB), TNF-α and IFN-γ in HCC tissues, which are the major cytotoxic mediators produced by T cells. Furthermore, TCS also resulted in an increase of mannose-6-phosphate receptor (M6PR), the major receptor of GrzB, in HCC tissues. In summary, these results suggest that TCS perhaps increases T-cell immunity via promoting the secretion of chemokines and accelerating the entry of GrzB to HCC cells, which highlights the potential role of TCS in anti-tumor immunotherapy.

Treatments against Polymorphosal discrepancies in Glioblastoma Multiforme

Glioblastoma (GB) are aggressive tumors that obstruct normal brain function. While the skull cannot expand in response to cancer growth, the growing pressure in the brain is generally the first sign. It can produce more frequent headaches, unexplained nausea or vomiting, blurred peripheral vision, double vision, a loss of feeling or movement in an arm or leg, and difficulty speaking and concentrating; all depend on the tumor's location. GB can also cause vascular thrombi, damaging endothelial cells and leading to red blood cell leakage. Latest studies have revealed the role of single nucleotide polymorphisms (SNPs) in developing and spreading cancers such as GB and breast cancer. Many discovered SNPs are associated with GB, particularly in great abundance in the promoter region, creating polygenetic vulnerability to glioma. This study aims to compile a list of some of the most frequent and significant SNPs implicated with GB formation and proliferation.

Epigenetic basis for PARP mutagenesis in glioblastoma: A review

Several modifications in the glioblastoma genes are caused by epigenetic modifications, which are crucial in appropriate developmental processes such as self-renewal and destiny determination of neural stem cells. Poly (ADP-ribose)polymerase (PARP) is an essential cofactor involved in DNA repair as well as several other cellular functions such as transcription and chromatin shape modification. Inhibiting PARP has evolved for triggering cell damage in cancerous cells when paired with certain other anticancer drugs including temozolomide (TMZ). PARP1 is involved with in base excision repair (BER) pathway, however its functionality differs across types of tumours. Epigenomics as well as chromosomal statistics have contributed to the growth of main subgroups of glioma, which serve as foundation for the categorization of central nervous system (CNS) tumours as well as a unique classification based only on DNA methylation information, which demonstrates extraordinary diagnostic accuracy. Unfortunately, not all patients respond to PARP inhibitors (PARPi), and there is no way to anticipate who will and who will not. In this field, PARPi are one of the innovative medicines currently being explored. As a result, cancer cells that also have a homologous recombination defect become fatal synthetically. As well as preparing the tumour microenvironment for immunotherapy, PARPi may enhance the lethal effects of chemotherapy and radiotherapy. This article analyzes the justification and clinical evidence for PARPi in glioma to offer potential therapeutic approaches. Despite the effectiveness of these targeted drugs, researchers have looked into a number of resistance mechanisms as well as the growing usage of PARPi in clinical practice for the treatment of various malignancies.

The Next Frontier in Health Disparities—A Closer Look at Exploring Sex Differences in Glioma Data and Omics Analysis, from Bench to Bedside and Back

Sex differences are increasingly being explored and reported in oncology, and glioma is no exception. As potentially meaningful sex differences are uncovered, existing gender-derived disparities mirror data generated in retrospective and prospective trials, real-world large-scale data sets, and bench work involving animals and cell lines. The resulting disparities at the data level are wide-ranging, potentially resulting in both adverse outcomes and failure to identify and exploit therapeutic benefits. We set out to analyze the literature on women’s data disparities in glioma by exploring the origins of data in this area to understand the representation of women in study samples and omics analyses. Given the current emphasis on inclusive study design and research, we wanted to explore if sex bias continues to exist in present-day data sets and how sex differences in data may impact conclusions derived from large-scale data sets, omics, biospecimen analysis, novel interventions, and standard of care management.

Regulated cell death (RCD) in cancer: key pathways and targeted therapies

Regulated cell death (RCD), also well-known as programmed cell death (PCD), refers to the form of cell death that can be regulated by a variety of biomacromolecules, which is distinctive from accidental cell death (ACD). Accumulating evidence has revealed that RCD subroutines are the key features of tumorigenesis, which may ultimately lead to the establishment of different potential therapeutic strategies. Hitherto, targeting the subroutines of RCD with pharmacological small-molecule compounds has been emerging as a promising therapeutic avenue, which has rapidly progressed in many types of human cancers. Thus, in this review, we focus on summarizing not only the key apoptotic and autophagy-dependent cell death signaling pathways, but the crucial pathways of other RCD subroutines, including necroptosis, pyroptosis, ferroptosis, parthanatos, entosis, NETosis and lysosome-dependent cell death (LCD) in cancer. Moreover, we further discuss the current situation of several small-molecule compounds targeting the different RCD subroutines to improve cancer treatment, such as single-target, dual or multiple-target small-molecule compounds, drug combinations, and some new emerging therapeutic strategies that would together shed new light on future directions to attack cancer cell vulnerabilities with small-molecule drugs targeting RCD for therapeutic purposes.

The Role of PARP ‐1 and NF‐κB in Bile‐Induced DNA Damage and Oncogenic Profile in Hypopharyngeal Cells

OBJECTIVES/HYPOTHESIS

We recently documented that acidic bile, a gastroesophageal reflux content, can cause invasive hypopharyngeal squamous cell carcinoma, by inducing widespread DNA damage and promoting nuclear factor kappa B (NF-κB)-related oncogenic molecular events. Poly or adenosine diphosphate (ADP)-ribose polymerase-1 (PARP-1), a sensitive sensor of DNA damage, may interact with NF-κB. We hypothesized that PARP-1 is activated in hypopharyngeal cells (HCs) with marked DNA damage caused by acidic bile, hence there is an association between PARP-1 and NF-κB activation or its related oncogenic profile, in this process.

STUDY DESIGN

In vitro study.

METHODS

We targeted PARP-1 and NF-κB(p65), using pharmacologic inhibitors, 1.0 μM Rucaparib (AG014699) and 10 μM BAY 11-7082 {3-[4=methylphenyl)sulfonyl]-(2E)-propenenitrile}, respectively, or silencing their gene expression (siRNAs) and used immunofluorescence, luciferase, cell viability, direct enzyme-linked immunosorbent assays, and qPCR analysis to detect the effect of targeting PARP-1 or NF-κB in acidic bile-induced DNA damage, PARP-1, p-NF-κB, and B-cell lymphoma 2 (Bcl-2) expression, as well as NF-κB transcriptional activity, cell survival, and mRNA oncogenic phenotype in HCs.

RESULTS

We showed that (i) PARP-1 is overexpressed by acidic bile, (ii) targeting NF-κB adequately prevents the acidic bile-induced DNA double-strand breaks (DSBs) by gamma H2A histone family member X (γH2AX), oxidative DNA/RNA damage, PARP-1 overexpression, anti-apoptotic mRNA phenotype, and cell survival, whereas (iii) targeting PARP-1 preserves elevated DNA damage, NF-κB activation, and anti-apoptotic phenotype.

CONCLUSION

We document for the first time that the activation of PARP-1 is an early event during bile reflux-related head and neck carcinogenesis and that NF-κB can mediate DNA damage and PARP-1 activation. Our data encourage further investigation into how acidic bile-induced activated NF-κB mediates DNA damage in hypopharyngeal carcinogenesis.

LEVEL OF EVIDENCE

NA Laryngoscope, 133:1146-1155, 2023.

Small Molecule Inhibitors in Adult High-Grade Glioma: From the Past to the Future

Glioblastoma is the most common primary malignant tumor in the brain and has a dismal prognosis despite patients accepting standard therapies. Alternation of genes and deregulation of proteins, such as receptor tyrosine kinase, PI3K/Akt, PKC, Ras/Raf/MEK, histone deacetylases, poly (ADP-ribose) polymerase (PARP), CDK4/6, branched-chain amino acid transaminase 1 (BCAT1), and Isocitrate dehydrogenase (IDH), play pivotal roles in the pathogenesis and progression of glioma. Simultaneously, the abnormalities change the cellular biological behavior and microenvironment of tumor cells. The differences between tumor cells and normal tissue become the vulnerability of tumor, which can be taken advantage of using targeted therapies. Small molecule inhibitors, as an important part of modern treatment for cancers, have shown significant efficacy in hematologic cancers and some solid tumors. To date, in glioblastoma, there have been more than 200 clinical trials completed or ongoing in which trial designers used small molecules as monotherapy or combination regimens to correct the abnormalities. In this review, we summarize the dysfunctional molecular mechanisms and highlight the outcomes of relevant clinical trials associated with small-molecule targeted therapies. Based on the outcomes, the main findings were that small-molecule inhibitors did not bring more benefit to newly diagnosed glioblastoma, but the clinical studies involving progressive glioblastoma usually claimed “noninferiority” compared with historical results. However, as to the clinical inferiority trial, similar dosing regimens should be avoided in future clinical trials.

Examples of Inverse Comorbidity between Cancer and Neurodegenerative Diseases: A Possible Role for Noncoding RNA

Cancer is one of the most common causes of death; in parallel, the incidence and prevalence of central nervous system diseases are equally high. Among neurodegenerative diseases, Alzheimer’s dementia is the most common, while Parkinson’s disease (PD) is the second most frequent neurodegenerative disease. There is a significant amount of evidence on the complex biological connection between cancer and neurodegeneration. Noncoding RNAs (ncRNAs) are defined as transcribed nucleotides that perform a variety of regulatory functions. The mechanisms by which ncRNAs exert their functions are numerous and involve every aspect of cellular life. The same ncRNA can act in multiple ways, leading to different outcomes; in fact, a single ncRNA can participate in the pathogenesis of more than one disease—even if these seem very different, as cancer and neurodegenerative disorders are. The ncRNA activates specific pathways leading to one or the other clinical phenotype, sometimes with obvious mechanisms of inverse comorbidity. We aimed to collect from the existing literature examples of inverse comorbidity in which ncRNAs seem to play a key role. We also investigated the example of mir-519a-3p, and one of its target genes Poly (ADP-ribose) polymerase 1, for the inverse comorbidity mechanism between some cancers and PD. We believe it is very important to study the inverse comorbidity relationship between cancer and neurodegenerative diseases because it will help us to better assess these two major areas of human disease.

Identification of Genes Related to DNA Repair Mechanism in Glioblastoma by Bioinformatics Methods

Objective: Aberrant expression of genes involved in DNA repair mechanisms (DRM) have been associated with radiation sensitivity of glioblastoma (GBM) cells. Identification of genes in DRM through bioinformatics methods may help identify potential novel therapeutic targets that can be used in GBM treatment. This study aims to identify genes that play a role in DRM in GBM using bioinformatics methods. Methods: Genes associated with DRM were identified using the “Reactome” and “KEGG” databases. The mRNA expression profiles of DRM related genes were analyzed in the GEO GDS1813 and GDS2853 datasets including GBM tumor samples using the "Orange Canvas" software. Genetic changes of genes were identified in GBM TCGA cases using the cBioPortal database. The GEPIA2 was used to show the effect of altered expression profiles of these genes on patient survival. Results: The mRNA expression profiles of ERCC6, FAN1, MBD4, PARP1 and UNG genes were found to be altered in GBM tumors. Mutations and copy number alterations for the identified genes were observed in TCGA GBM cases. The overall survival and disease-free survival of TCGA GBM patients were not significantly different between high and low expression groups. Conclusion: ERCC6, PARP1 and UNG genes identified in the current study may be potential therapeutic targets that can increase the efficacy of radiotherapy in GBM in case of their suppression.

The use of radiosensitizing agents in the therapy of glioblastoma multiforme-a comprehensive review

BACKGROUND

Glioblastoma is the most common malignant brain tumor in human adults. Despite several improvements in resective as well as adjuvant therapy over the last decades, its overall prognosis remains poor. As a means of improving patient outcome, the possibility of enhancing radiation response by using radiosensitizing agents has been tested in an array of studies.

METHODS

A comprehensive review of clinical trials involving radiation therapy in combination with radiosensitizing agents on patients diagnosed with glioblastoma was performed in the National Center for Biotechnology Information's PubMed database.

RESULTS

A total of 96 papers addressing this matter were published between 1976 and 2021, of which 63 matched the subject of this paper. All papers were reviewed, and their findings discussed in the context of their underlining mechanisms of radiosensitization.

CONCLUSION

In the history of glioblastoma treatment, several approaches of optimizing radiation-effectiveness using radiosensitizers have been made. Even though several different strategies and agents have been explored, clear evidence of improved patient outcome is still missing. Tissue-selectiveness and penetration of the blood-brain barrier seem to be major roadblocks; nevertheless, modern strategies try to circumvent these obstacles, using novel sensitizers based on preclinical data or alternative ways of delivery.

Perspective on the Use of DNA Repair Inhibitors as a Tool for Imaging and Radionuclide Therapy of Glioblastoma

Simple Summary

The current routine treatment for glioblastoma (GB), the most lethal high-grade brain tumor in adults, aims to induce DNA damage in the tumor. However, the tumor cells might be able to repair that damage, which leads to therapy resistance. Fortunately, DNA repair defects are common in GB cells, and their survival is often based on a sole backup repair pathway. Hence, targeted drugs inhibiting essential proteins of the DNA damage response have gained momentum and are being introduced in the clinic. This review gives a perspective on the use of radiopharmaceuticals targeting DDR kinases for imaging in order to determine the DNA repair phenotype of GB, as well as for effective radionuclide therapy. Finally, four new promising radiopharmaceuticals are suggested with the potential to lead to a more personalized GB therapy.

Abstract

Despite numerous innovative treatment strategies, the treatment of glioblastoma (GB) remains challenging. With the current state-of-the-art therapy, most GB patients succumb after about a year. In the evolution of personalized medicine, targeted radionuclide therapy (TRT) is gaining momentum, for example, to stratify patients based on specific biomarkers. One of these biomarkers is deficiencies in DNA damage repair (DDR), which give rise to genomic instability and cancer initiation. However, these deficiencies also provide targets to specifically kill cancer cells following the synthetic lethality principle. This led to the increased interest in targeted drugs that inhibit essential DDR kinases (DDRi), of which multiple are undergoing clinical validation. In this review, the current status of DDRi for the treatment of GB is given for selected targets: ATM/ATR, CHK1/2, DNA-PK, and PARP. Furthermore, this review provides a perspective on the use of radiopharmaceuticals targeting these DDR kinases to (1) evaluate the DNA repair phenotype of GB before treatment decisions are made and (2) induce DNA damage via TRT. Finally, by applying in-house selection criteria and analyzing the structural characteristics of the DDRi, four drugs with the potential to become new therapeutic GB radiopharmaceuticals are suggested.

In Vitro and Computational Studies of Perezone and Perezone Angelate as Potential Anti-Glioblastoma Multiforme Agents

Glioblastoma multiforme (GBM) represents the most malignant type of astrocytoma, with a life expectancy of two years. It has been shown that Poly (ADP-ribose) polymerase 1 (PARP-1) protein is over-expressed in GBM cells, while its expression in healthy tissue is low. In addition, perezone, a phyto-compound, is a PARP-1 inhibitor with anti-neoplastic activity. As a consequence, in the present study, both in vitro and computational evaluations of perezone and its chemically related compound, perezone angelate, as anti-GBM agents were performed. Hence, the anti-proliferative assay showed that perezone angelate induces higher cytotoxicity in the GBM cell line (U373 IC50 = 6.44 μM) than perezone (U373 IC50 = 51.20 μM) by induction of apoptosis. In addition, perezone angelate showed low cytotoxic activity in rat glial cells (IC50 = 173.66 μM). PARP-1 inhibitory activity (IC50 = 5.25 μM) and oxidative stress induction by perezone angelate were corroborated employing in vitro studies. In the other hand, the performed docking studies allowed explaining the PARP-1 inhibitory activity of perezone angelate, and ADMET studies showed its probability to permeate cell membranes and the blood–brain barrier, which is an essential characteristic of drugs to treat neurological diseases. Finally, it is essential to highlight that the results confirm perezone angelate as a potential anti-GBM agent.

Recent developments in drug delivery strategies for targeting DNA damage response in glioblastoma

Glioblastoma is the most frequent and malignant brain tumor. The median survival for this disease is approximately 15 months, and despite all the available treatment strategies employed, it remains an incurable disease. Preclinical and clinical research have shown that the resistance process related to DNA damage repair pathways, glioma stem cells, blood-brain barrier selectivity, and dose-limiting toxicity of systemic treatment leads to poor clinical outcomes. In this context, the advent of drug delivery systems associated with localized treatment seems to be a promising and versatile alternative to overcome the failure of the current treatment approaches. In order to bypass therapeutic tumor resistance mechanisms, more effective combinatorial therapies should be identified, such as the use of cytotoxic drugs combined with the inhibition of DNA damage response (DDR)-related targets. Additionally, critical reasoning about the delivery approach and administration route in brain tumors treatment innovation is essential. The outcomes of future experimental studies regarding the association of delivery systems, alternative treatment routes, and DDR targets are expected to lead to the development of refined therapeutic interventions. Novel therapeutic approaches could improve the life's quality of glioblastoma patients and increase their survival rate.

Poly (ADP-Ribose) Polymerase 1 Regulates Cajal-Retzius Cell Development and Neural Precursor Cell Adhesion

Poly (ADP-ribose) polymerase 1 (PARP1) is a ubiquitously expressed enzyme that regulates DNA damage repair, cell death, inflammation, and transcription. PARP1 functions by adding ADP-ribose polymers (PAR) to proteins including itself, using NAD⁺ as a donor. This post-translational modification known as PARylation results in changes in the activity of PARP1 and its substrate proteins and has been linked to the pathogenesis of various neurological diseases. PARP1 KO mice display schizophrenia-like behaviors, have impaired memory formation, and have defects in neuronal proliferation and survival, while mutations in genes that affect PARylation have been associated with intellectual disability, psychosis, neurodegeneration, and stroke in humans. Yet, the roles of PARP1 in brain development have not been extensively studied. We now find that loss of PARP1 leads to defects in brain development and increased neuronal density at birth. We further demonstrate that PARP1 loss increases the expression levels of genes associated with neuronal migration and adhesion in the E15.5 cerebral cortex, including Reln. This correlates with an increased number of Cajal–Retzius (CR) cells in vivo and in cultures of embryonic neural progenitor cells (NPCs) derived from the PARP1 KO cortex. Furthermore, PARP1 loss leads to increased NPC adhesion to N-cadherin, like that induced by experimental exposure to Reelin. Taken together, these results uncover a novel role for PARP1 in brain development, i.e., regulation of CR cells, neuronal density, and cell adhesion.

BRCAness as a Biomarker of Susceptibility to PARP Inhibitors in Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is the most common primary brain cancer. GBMs commonly acquire resistance to standard-of-care therapies. Among the novel means to sensitize GBM to DNA-damaging therapies, a promising strategy is to combine them with inhibitors of the DNA damage repair (DDR) machinery, such as inhibitors for poly(ADP-ribose) polymerase (PARP). PARP inhibitors (PARPis) have already shown efficacy and have received regulatory approval for breast, ovarian, prostate, and pancreatic cancer treatment. In these cancer types, after PARPi administration, patients carrying specific mutations in the breast cancer 1 (BRCA1) and 2 (BRCA2) suppressor genes have shown better response when compared to wild-type carriers. Mutated BRCA genes are infrequent in GBM tumors, but their cells can carry other genetic alterations that lead to the same phenotype collectively referred to as 'BRCAness'. The most promising biomarkers of BRCAness in GBM are related to isocitrate dehydrogenases 1 and 2 (IDH1/2), epidermal growth factor receptor (EGFR), phosphatase and tensin homolog (PTEN), MYC proto-oncogene, and estrogen receptors beta (ERβ). BRCAness status identified by accurate biomarkers can ultimately predict responsiveness to PARPi therapy, thereby allowing patient selection for personalized treatment. This review discusses potential biomarkers of BRCAness for a 'precision medicine' of GBM patients.

Genotoxic therapy and resistance mechanism in gliomas

Glioma is one of the most common and lethal brain tumors. Surgical resection followed by radiotherapy plus chemotherapy is the current standard of care for patients with glioma. The existence of resistance to genotoxic therapy, as well as the nature of tumor heterogeneity greatly limits the efficacy of glioma therapy. DNA damage repair pathways play essential roles in many aspects of glioma biology such as cancer progression, therapy resistance, and tumor relapse. O6-methylguanine-DNA methyltransferase (MGMT) repairs the cytotoxic DNA lesion generated by temozolomide (TMZ), considered as the main mechanism of drug resistance. In addition, mismatch repair, base excision repair, and homologous recombination DNA repair also play pivotal roles in treatment resistance as well. Furthermore, cellular mechanisms, such as cancer stem cells, evasion from apoptosis, and metabolic reprogramming, also contribute to TMZ resistance in gliomas. Investigations over the past two decades have revealed comprehensive mechanisms of glioma therapy resistance, which has led to the development of novel therapeutic strategies and targeting molecules.

BKM120 sensitizes glioblastoma to the PARP inhibitor rucaparib by suppressing homologous recombination repair

PARP inhibitors have been approved for the therapy of cancers with homologous recombination (HR) deficiency based on the concept of "synthetic lethality". However, glioblastoma (GBM) patients have gained little benefit from PARP inhibitors due to a lack of BRCA mutations. Herein, we demonstrated that concurrent treatment with the PARP inhibitor rucaparib and the PI3K inhibitor BKM120 showed synergetic anticancer effects on GBM U251 and U87MG cells. Mechanistically, BKM120 decreased expression of HR molecules, including RAD51 and BRCA1/2, and reduced HR repair efficiency in GBM cells, therefore increasing levels of apoptosis induced by rucaparib. Furthermore, we discovered that the two compounds complemented each other in DNA damage response and drug accumulation. Notably, in the zebrafish U87MG-RFP orthotopic xenograft model, nude mouse U87MG subcutaneous xenograft model and U87MG-Luc orthotopic xenograft model, combination showed obviously increased antitumor efficacy compared to each monotherapy. Immunohistochemical analysis of tumor tissues indicated that the combination obviously reduced expression of HR repair molecules and increased the DNA damage biomarker γ-H2AX, consistent with the in vitro results. Collectively, our findings provide new insight into combined blockade of PI3K and PARP, which might represent a promising therapeutic approach for GBM.

Cucurbitacin IIa: A review of phytochemistry and pharmacology

Cucurbitacin IIa was first found in plants and it belongs to tetracyclo triterpenoids. It is one of the most important active components in cucurbitaceae plants. Studies have found that cucurbitacin IIa has a variety of pharmacological effects, such as antitumor, antiinflammatory, antibacterial, antihepatitis B virus, inhibition of human immunodeficiency virus replication, and antidepressant effect. However, the underlying mechanisms, intracellular targets, and structure-activity relationships of cucurbitacin IIa remain to be completely elucidated. This review summarizes the current advances concerning the phytochemistry and pharmacology of cucurbitacin IIa. Electronic databases such as PubMed, Web of Science, Google Scholar, Science Direct, and CNKI were used to find relevant information about cucurbitacin IIa using keywords such as "Cucurbitacin IIa," "Pharmacology," and "Phytochemistry." These pharmacological effects involve the actin cytoskeleton aggregation, the regulation of JAK2/STAT3, ERBB-MAPK, CaMKII α/CREB/BDNF signal pathways, as well as the regulation of survivin, caspases, and other cell cycles, apoptosis, autophagy-related cytokines, and kinases. It has high development and use value.

Poly (ADP-ribose) polymerase 1 and Parkinson's disease: A study in post-mortem human brain

Poly (ADP-ribose) polymerase 1 (PARP1) is crucial in both maintenance of genome integrity and cell death. PARP1 activation has been very recently linked to Parkinson's disease (PD) and its role in inducing the pathologic accumulation of α-Synuclein demonstrated in a PD mouse model. The objective of this study was to investigate the presence and localization of PARP1 in PD brain. PARP1 localization was assessed by immunostaining and confocal microscopy in post-mortem human brains obtained from PD patients (Braak stage VI) compared to controls. PARP1 positive nuclei in substantia nigra, mainly in dopaminergic neurons but also in astrocytes and oligodendrocytes, were decreased in PD. The same alteration was observed in several areas that are affected in PD pathology, namely the dorsal motor nucleus of vagus, frontal and cingulate cortex, whereas no changes in PARP1 staining were detectable in the inferior olivary nucleus that is unaffected in PD. In addition, PARP1 co-localizes with α-Synuclein that is accumulated in the cytoplasm and in Lewy bodies of PD tissue sections. Our data reveal previously unknown changes of PARP1 localization in the brain of PD patients, in both neurons and glia, supporting its widespread involvement in this pathology and its potential use as a therapeutic target.

TAK1 Inhibitor Enhances the Therapeutic Treatment for Glioblastoma

Glioblastoma (GBM) is a brain tumor characterized by poor therapeutic response and overall survival. Despite relevant progress in conventional treatments represented by the clinical use of temozolomide (TMZ), a combination of approaches might be a possible future direction for treating GBM. Transforming growth factor-beta-activated kinase-1 (TAK1) is an essential component in genotoxic stresses-induced NF-κB-activation and mitogen-activated protein kinase (MAPK)-pathways; however, the role of TAK1 in GBM-chemoresistance remains unknown. This study aimed to verify, in GBM human cell lines, in an in vivo U87-xenograft model and in TMZ-treated-patients, the effect of TAK1 inhibition on the sensitivity of GBM cells to chemotherapy. In vitro model, using GBM cell lines, showed that 5Z-7-oxozeaenol augmented the cytotoxic effects of TMZ, blocking TMZ-induced NF-κB-activation, reducing DNA-damage and enhancing TMZ-induced apoptosis in GMB cell lines. We showed a reduction in tumor burden as well as tumor volume in the xenograft model following the treatment with 5Z-7-oxozaenol associated with TMZ. Our results showed a significant up-regulation in TAK1, p-p38, p-JNK and NF-κB in glioblastoma TMZ-treated-patients and denoted the role of 5Z-7-oxozeaenol in increasing the sensitivity of GBM cells to chemotherapy, proving to be an effective coadjuvant to current GBM chemotherapeutic regimens, suggesting a new option for therapeutic treatment of GBM.

Pharmacokinetics, safety, and tolerability of olaparib and temozolomide for recurrent glioblastoma: results of the phase I OPARATIC trial

BACKGROUND

The poly(ADP-ribose) polymerase (PARP) inhibitor olaparib potentiated radiation and temozolomide (TMZ) chemotherapy in preclinical glioblastoma models but brain penetration was poor. Clinically, PARP inhibitors exacerbate the hematological side effects of TMZ. The OPARATIC trial was conducted to measure penetration of recurrent glioblastoma by olaparib and assess the safety and tolerability of its combination with TMZ.

METHODS

Preclinical pharmacokinetic studies evaluated olaparib tissue distribution in rats and tumor-bearing mice. Adult patients with recurrent glioblastoma received various doses and schedules of olaparib and low-dose TMZ in a 3 + 3 design. Suitable patients received olaparib prior to neurosurgical resection; olaparib concentrations in plasma, tumor core and tumor margin specimens were measured by mass spectrometry. A dose expansion cohort tested tolerability and efficacy of the recommended phase II dose (RP2D). Radiosensitizing effects of olaparib were measured by clonogenic survival in glioblastoma cell lines.

RESULTS

Olaparib was a substrate for multidrug resistance protein 1 and showed no brain penetration in rats but was detected in orthotopic glioblastoma xenografts. Clinically, olaparib was detected in 71/71 tumor core specimens (27 patients; median, 496 nM) and 21/21 tumor margin specimens (9 patients; median, 512.3 nM). Olaparib exacerbated TMZ-related hematological toxicity, necessitating intermittent dosing. RP2D was olaparib 150 mg (3 days/week) with TMZ 75 mg/m2 daily for 42 days. Fourteen (36%) of 39 evaluable patients were progression free at 6 months. Olaparib radiosensitized 6 glioblastoma cell lines at clinically relevant concentrations of 100 and 500 nM.

CONCLUSION

Olaparib reliably penetrates recurrent glioblastoma at radiosensitizing concentrations, supporting further clinical development and highlighting the need for better preclinical models.

A therapeutic update on PARP inhibitors: implications in the treatment of glioma

Central nervous system (CNS) cancers are among the most aggressive and devastating. Further, due to unavailability of neuro-oncologists and neurosurgeons, the specialized treatment options of CNS cancers are still not completely available in most parts of the world. Among various strategies of inducing death in cancer cells, inhibition of poly(ADP-ribose) polymerase (PARP) has emerged as a beneficial therapy when combined with other anticancer agents. In this review, we provide a detailed therapeutic update of PARP inhibitors that have shown clinical activity against glioma.

The Promise of Poly(ADP-Ribose) Polymerase (PARP) Inhibitors in Gliomas

Diffuse infiltrating gliomas are a clinically and molecularly heterogeneous group of tumors that are uniformly incurable. Despite our growing knowledge of genomic and epigenomic alterations in gliomas, standard treatments have not changed in the past 2 decades and remain limited to surgical resection, ionizing radiation, and alkylating chemotherapeutic agents. Development of novel therapeutics for diffuse gliomas has been challenging due to inter- and intra-tumoral heterogeneity, diffuse infiltrative nature of gliomas, inadequate tumor/drug concentration due to blood-brain barrier, and an immunosuppressive tumor microenvironment. Given the high frequency of DNA damage pathway alterations in gliomas, researchers have focused their efforts in targeting the DNA damage pathways for the treatment of gliomas. A growing body of data has shed light on the role of poly(ADP-ribose) polymerase (PARP) in combination with radiation and temozolomide in high-grade gliomas. Furthermore, a novel therapeutic strategy in low-grade glioma is the recent elucidation for a potential role of PARP inhibitors in gliomas with IDH1/2 mutations. This review highlights the concepts behind targeting PARP in gliomas with a focus on putative predictive biomarkers of response. We further discuss the challenges involved in the successful development of PARP inhibitors in gliomas, including the intracranial location of the tumor and overlapping toxicities with current standards of care, and promising strategies to overcome these hurdles.

An assessment of poly (ADP-ribose) polymerase-1 role in normal and cancer cells

Poly (ADP-ribose) polymerase (PARP) is a superfamily of 18 proteins characterized by the PARP homology domain, the catalytic domain. This catalytic domain helps in the ADP-ribosylation of various acceptor proteins using nicotinamide adenine dinucleotide (NAD+) as a donor for ADP-ribose. PARP-1 and PARP-2 carry out 80% of poly-ADP-ribosylation of cellular protein. Hence, their combined knockout results in embryonic lethality of mice. PARP-1 consists of three major domains, namely, DNA binding domain, automodification domain, and a catalytic domain. These domains further consist of subdomains and motifs, which helps PARP-1 in a diverse function. PARP-1 is mainly involved in DNA damage detection and repair, but emerging evidence suggests its role in many other functions such as DNA synthesis, replication, apoptosis, necrosis, and cancer progression. Herein, we review the current state of the PARP-1 role in DNA damage repair and other biological processes including epithelial to mesenchymal transition (EMT). We have also observed the role of PARP-1 in modulating EMT regulators like E-cadherin, Vimentin, Claudin-1, Snail, Smad-4, Twist-1, and β-catenin. Here, we have also attempted to relate the role of PARP-1 in EMT of cancer cells.

Preclinical and first-in-human-brain-cancer applications of [18F]poly (ADP-ribose) polymerase inhibitor PET/MR

Background

We report preclinical and first-in-human-brain-cancer data using a targeted poly (ADP-ribose) polymerase 1 (PARP1) binding PET tracer, [¹⁸F]PARPi, as a diagnostic tool to differentiate between brain cancers and treatment-related changes.

Methods

We applied a glioma model in p53-deficient nestin/tv-a mice, which were injected with [¹⁸F]PARPi and then sacrificed 1 h post-injection for brain examination. We also prospectively enrolled patients with brain cancers to undergo dynamic [¹⁸F]PARPi acquisition on a dedicated positron emission tomography/magnetic resonance (PET/MR) scanner. Lesion diagnosis was established by pathology when available or by Response Assessment in Neuro-Oncology (RANO) or RANO-BM response criteria. Resected tissue also underwent PARPi-FL staining and PARP1 immunohistochemistry.

Results

In a preclinical mouse model, we illustrated that [¹⁸F]PARPi crossed the blood–brain barrier and specifically bound to PARP1 overexpressed in cancer cell nuclei. In humans, we demonstrated high [¹⁸F]PARPi uptake on PET/MR in active brain cancers and low uptake in treatment-related changes independent of blood–brain barrier disruption. Immunohistochemistry results confirmed higher PARP1 expression in cancerous than in noncancerous tissue. Specificity was also corroborated by blocking fluorescent tracer uptake with an excess unlabeled PARP inhibitor in patient cancer biospecimen.

Conclusions

Although larger studies are necessary to confirm and further explore this tracer, we describe the promising performance of [¹⁸F]PARPi as a diagnostic tool to evaluate patients with brain cancers and possible treatment-related changes.

Stenotrophomonas maltophilia outer membrane protein A induces epithelial cell apoptosis via mitochondrial pathways

Stenotrophomonas maltophilia (S. maltophilia) is a common opportunistic pathogen in intensive care units and causes infections most often after surgeries in immune-compromised patients such as those undergoing chemotherapy. Outer membrane protein A (OmpA) is the most abundant of the outer membrane proteins in S. maltophilia. Previous studies on OmpA usually focus on its interaction with the host cells and its role in vaccine development. However, the impact of OmpA on the virulence of S. maltophilia to host cells and the effects on apoptosis remain unclear. In this study, we exposed purified recombinant S. maltophilia OmpA (rOmpA) to HEp-2 cells and investigated the effects of OmpA on epithelial cell apoptosis. Morphologic and flow cytometric analyses revealed that HEp-2 cells stimulated with rOmpA multiple apoptosis features, including nuclear roundness and pyknosis, chromatin aggregation, and phosphatidylserine eversion. We found that rOmpA regulated the protein levels of Bax and Bcl-xL in HEp-2 cells, leading to changes in mitochondria permeability and the release of cytochrome c and apoptosis-inducing factors into the cytoplasm. These subsequently activate the caspase-9/caspase-3 pathway that promote apoptosis. We also observed that rOmpA enhanced the generation of reactive oxygen species and increased intracellular Ca²⁺ levels in HEp-2 cells. Collectively, our data suggested that rOmpA induced epithelial cells apoptosis via mi-tochondrial pathways.

Targeting the DNA Damage Response to Overcome Cancer Drug Resistance in Glioblastoma

Glioblastoma multiforme (GBM) is a severe brain tumor whose ability to mutate and adapt to therapies is at the base for the extremely poor survival rate of patients. Despite multiple efforts to develop alternative forms of treatment, advances have been disappointing and GBM remains an arduous tumor to treat. One of the leading causes for its strong resistance is the innate upregulation of DNA repair mechanisms. Since standard therapy consists of a combinatory use of ionizing radiation and alkylating drugs, which both damage DNA, targeting the DNA damage response (DDR) is proving to be a beneficial strategy to sensitize tumor cells to treatment. In this review, we will discuss how recent progress in the availability of the DDR kinase inhibitors will be key for future therapy development. Further, we will examine the principal existing DDR inhibitors, with special focus on those currently in use for GBM clinical trials.

Poly (ADP-Ribose) Polymerase 1 Protein Expression in Normal Pancreas and Pancreatic Adenocarcinoma

Pancreatic cancer is a most frequent cancer in Europe, and the majority of cases of cancer of the pancreas are diagnosed above the age of 65. Radical surgery is the first curative treatment of pancreatic cancer, and alternative or combined therapeutic options, in particular, consist of adjuvant or neoadjuvant chemotherapy, with or without radiotherapy. Many factors, including diet and genetics, have been implicated in the development of cancer of the pancreas. Poly (ADP-ribose) polymerase 1 (PARP-1) protein is required for translocation of the apoptosis-inducing factor (AIF) from the mitochondria to the nucleus. It is involved in programmed cell death processes. Different PARP-1 gene expression proteins have been observed in various tumors such as lung, ovarian, endometrial, skin, and glioblastoma. We evaluated the expression of PARP-1 protein in pancreatic adenocarcinoma and normal pancreas tissues by immunohistochemistry. Protein PARP-1 in the nucleus was found in all samples (normal pancreas and pancreatic adenocarcinoma tissues). No cytoplasmic staining was observed in any sample. PARP-1-positive cells resulted higher in the normal pancreas compared with the pancreas with adenocarcinoma. PARP-1 overexpression in prostate cancer tissue compared with normal prostate suggests a greater activity of PARP-1 in these tumors. These findings suggest that PARP-1 expression in prostate cancer is an attempt to trigger apoptosis in this type of tumor, similarl to that reported in other cancers. This finding suggests that PARP-1-mediated cell death pathways are inhibited in this cancer.

Targeted Brain Tumor Radiotherapy Using an Auger Emitter

PURPOSE

Glioblastoma multiforme is a highly aggressive form of brain cancer whose location, tendency to infiltrate healthy surrounding tissue, and heterogeneity significantly limit survival, with scant progress having been made in recent decades.

EXPERIMENTAL DESIGN

123I-MAPi (Iodine-123 Meitner-Auger PARP1 inhibitor) is a precise therapeutic tool composed of a PARP1 inhibitor radiolabeled with an Auger- and gamma-emitting iodine isotope. Here, the PARP inhibitor, which binds to the DNA repair enzyme PARP1, specifically targets cancer cells, sparing healthy tissue, and carries a radioactive payload within reach of the cancer cells' DNA.

RESULTS

The high relative biological efficacy of Auger electrons within their short range of action is leveraged to inflict DNA damage and cell death with high precision. The gamma ray emission of 123I-MAPi allows for the imaging of tumor progression and therapy response, and for patient dosimetry calculation. Here we demonstrated the efficacy and specificity of this small-molecule radiotheranostic in a complex preclinical model. In vitro and in vivo studies demonstrate high tumor uptake and a prolonged survival in mice treated with 123I-MAPi when compared with vehicle controls. Different methods of drug delivery were investigated to develop this technology for clinical applications, including convection enhanced delivery and intrathecal injection.

CONCLUSIONS

Taken together, these results represent the first full characterization of an Auger-emitting PARP inhibitor which demonstrate a survival benefit in mouse models of GBM and confirm the high potential of 123I-MAPi for clinical translation.

Synergic pro-apoptotic effects of Ferulic Acid and nanostructured lipid carrier in glioblastoma cells assessed through molecular and Delayed Luminescence studies

Herein, we assessed the effect of Ferulic Acid (FA), a natural antioxidant with anti-cancer effect, on the human glioblastoma cells through molecular and Delayed Luminescence (DL) studies. DL, a phenomenon of ultra-week emission of optical photons, was used to monitor mitochondrial assessment. The effect of FA loaded in nanostructured lipid carriers (NLCs) was also assessed. To validate NLCs as a drug delivery system for glioblastoma treatment, particular attention was focused on their effect. We found that free FA induced a significant decrease in c-Myc and Bcl-2 expression levels accompanied by the apoptotic pathway activation. Blank NLCs, even if they did not induce cytotoxicity and caspase-3 cleavage, decreased Bcl-2, ERK1/2, c-Myc expression levels activating PARP-1 cleavage. The changes in DL intensity and kinetics highlighted a possible effect of nanoparticle matrix on mitochondria, through the involvement of the NADH pool and ROS production that, in turn, activates ERK1/2 pathways. All the effects on protein expression levels and on the activation of apoptotic pathway appeared more evident when the cells were exposed to FA loaded in NLCs. We demonstrated that the observed effects are due to a synergic pro-apoptotic influence exerted by FA, whose bio-availability increases in the glioblastoma cells, and NLCs formulation.

PARP1 V762A polymorphism affects the prognosis of myelodysplastic syndromes

OBJECTIVE

Myelodysplastic syndromes (MDS), caused by various genetic mutations in hematopoietic stem cells, are associated with highly variable outcomes. Poly (ADP-ribose) polymerase-1 (PARP1) plays an important role in DNA damage repair and contributes to the progression of several types of cancer. Here, we investigated the impact of PARP1 V762A polymorphism on the susceptibility to and prognosis of MDS.

METHODS

Samples collected from 105 MDS patients and 202 race-matched healthy controls were subjected to polymerase chain reaction-restriction fragment length polymorphism for genotyping.

RESULTS

The allele and genotype frequencies of PARP1 V762A did not differ between MDS patients and the control group. However, MDS patients with the PARP1 V762A non-AA genotype, which is associated with high gene activity, had shorter overall survival rates (P = .01) than those with the AA genotype. Multivariate analysis of overall survival also revealed PARP1 V762A non-AA genotype as a poor prognostic factor (P = .02). When patients were analyzed according to treatment history, the PARP1 V762A non-AA genotype was only associated with poor survival in patients who had received treatment (P = .02).

CONCLUSION

PARP1 V762A polymorphism may be an independent prognostic factor for MDS, and a predictive biomarker for MDS treatment.

Targeting DNA repair in gliomas

PURPOSE OF REVIEW

Gliomas represent a disparate group of malignancies with varying clinical outcomes despite a tremendous amount of time, effort, and resources dedicated to their management and understanding. The most aggressive entity, glioblastoma, has a dismal prognosis with poor local control despite intense local and systemic treatment, including radiation therapy.

RECENT FINDINGS

Given the heterogeneity in genotype, phenotype, and patient outcomes, researchers and clinicians have turned their attention toward attacking DNA damage response and repair mechanisms in gliomas in an effort to develop novel chemo and radiosensitizers. However, despite extensive work in both the laboratory and the clinic, no sensitizers have yet to emerge as clear options in the treatment of glioma, often because of meager preclinical data or an inability to penetrate the blood-brain barrier.

SUMMARY

This review will examine current understanding of molecular DNA repair targets in glioma and their potential exploitation to improve local control and, ultimately, overall survival of patients afflicted with these diseases.

Fluorescence anisotropy imaging in drug discovery

Non-invasive measurement of drug-target engagement can provide critical insights in the molecular pharmacology of small molecule drugs. Fluorescence polarization/fluorescence anisotropy measurements are commonly employed in protein/cell screening assays. However, the expansion of such measurements to the in vivo setting has proven difficult until recently. With the advent of high-resolution fluorescence anisotropy microscopy it is now possible to perform kinetic measurements of intracellular drug distribution and target engagement in commonly used mouse models. In this review we discuss the background, current advances and future perspectives in intravital fluorescence anisotropy measurements to derive pharmacokinetic and pharmacodynamic measurements in single cells and whole organs.

microRNAs: Potential glioblastoma radiosensitizer by targeting radiation-related molecular pathways

Glioblastoma (GBM) is the most lethal type of primary brain tumor. Currently, even with optimal and multimodal cancer therapies, the survival rate of GBM patients remains poor. One reason for inadequate response of GBM tumors to radiotherapy is radioresistance (RR). Thus, there is a critical need for new insights about GBM treatment to increase the chance of treatment. microRNAs (miRNAs) are important regulatory molecules that can effectively control GBM radiosensitivity (RS) by affecting radiation-related signal transduction pathways such as apoptosis, proliferation, DNA repair and cell cycle regulation. miRNAs provide new clinical perspectives for developing effective GBM treatments. A growing body of literature has demonstrated that GBM RS can be modified by modulating the expression of miRNAs such as miR-7, miR-10b, miR-124, miR-128, miR-320, miR-21, miR-203, and miR-153. This paper highlights the miRNAs and the underlying molecular mechanisms that are involved in the RS of GBM. Besides highlighting the role of miRNAs in different signaling pathways, we explain the mechanisms that affect RS of GBM for modulating radiation response at the clinical level.

Treatment of Pediatric Glioblastoma with Combination Olaparib and Temozolomide Demonstrates 2-Year Durable Response

For pediatric patients with high-grade gliomas, standard-of-care treatment includes surgery, chemotherapy, and radiation therapy; however, most patients ultimately succumb to their disease. With advances in genomic characterization of pediatric high-grade gliomas, the use of targeted therapies in combination with current treatment modalities offer the potential to improve survival in this patient population. In this report, we present the case of a 3-year-old girl with glioblastoma who continues to experience an exceptional and durable response (>2 years) to the poly (ADP-ribose) polymerase (PARP) inhibitor olaparib. Our patient presented with persistent and progressive seizure activity that upon workup was the result of a large heterogeneously enhancing, mixed cystic and solid mass in the left frontal-parietal-temporal region. Histopathologic analysis of resected tumor tissue confirmed the diagnosis of glioblastoma, and comprehensive genomic profiling demonstrated absence of any BRAF or H3F3A mutations. Genomic profiling, however, did reveal a probable germline heterozygous BRCA2 Lys3326Ter (K3226*) nonsense variant. After debulking surgery, the patient received standard-of-care treatment with radiation and temozolomide. Nine months later the PARP inhibitor olaparib was administered in combination with temozolomide for 16 cycles. This regimen was well tolerated by the patient and serial imaging showed reduction in tumor size. Since completion of the regimen, the patient remains neurologically intact with no evidence of tumor recurrence. To our knowledge, this represents the first case of a pediatric glioblastoma that maintains a durable response to a therapeutic strategy that included the PARP inhibitor olaparib and more generally highlights the potential clinical utility of incorporating these agents into the treatment of pediatric high-grade gliomas. KEY POINTS: Germline mutations detected in pediatric gliomas may represent a cancer predisposition syndrome. Integrating molecular testing into routine clinical care for pediatric patients with glioma is critical to identify therapeutic targets and patients with a cancer predisposition syndrome. Patients with glioma with defects in DNA repair pathway components (e.g., BRCA1/2) may show increased responsiveness to poly (ADP-ribose) polymerase (PARP) inhibitors. Combining PARP inhibitors with temozolomide (standard-of-care treatment) revealed no adverse events or toxicities over the course of 18 months.