OGG1 competitive inhibitors show important off-target effects by directly inhibiting efflux pumps and disturbing mitotic progression

Modulation of OGG1 enzymatic activities by small molecules, promising tools and current challenges

Oxidative DNA damage, resulting from endogenous cellular processes and external sources plays a significant role in mutagenesis, cancer progression, and the pathogenesis of neurological disorders. Base Excision Repair (BER) is involved in the repair of base modifications such as oxidations or alkylations as well as single strand breaks. The DNA glycosylase OGG1, initiates the BER pathway by the recognition and excision of 8oxoG, the most common oxidative DNA lesion, in both nuclear and mitochondrial DNA. Beyond DNA repair, OGG1 modulates transcription, particularly pro-inflammatory genes, linking oxidative DNA damage to broader biological processes like inflammation and aging. In cancer therapy, BER inhibition has emerged as a promising strategy to enhance treatment efficacy. Targeting OGG1 sensitizes cells to chemotherapies, radiotherapies, and PARP inhibitors, presenting opportunities to overcome therapy resistance. Additionally, OGG1 activators hold potential in mitigating oxidative damage associated with aging and neurological disorders. This review presents the development of several inhibitors and activators of OGG1 and how they have contributed to advance our knowledge in the fundamental functions of OGG1. We also discuss the new opportunities they provide for clinical applications in treating cancer, inflammation and neurological disorders. Finally, we also highlight the challenges in targeting OGG1, particularly regarding the off-target effects recently reported for some inhibitors and how we can overcome these limitations.

Suppression of 8-oxoguanine DNA glycosylase (OGG1) activity produced positive impacts on disease severity, survival, and histopathological features of mice infected with Plasmodium berghei

Malaria is a life-threatening disease, leading to significant morbidity and mortality. Malaria treatment remains a challenge due to its intricate pathophysiology and high levels of parasite resistance to many currently available antimalarial agents. Thus, there is an urgent need for more therapeutic strategies to combat the disease. OGG1 activity has been implicated in many inflammatory disease conditions, making suppressing OGG1 activity a potential target for therapeutic purposes. The current study aimed to determine the effect of suppressing OGG1 activity on the severity, survival, and histopathological features of P. berghei-infected mice. In this study, the effects of modulating OGG1 activity on parasitaemia development, disease progression, survival rate, and histopathological outcomes in major organs of Plasmodium berghei (P. berghei) infected mice were evaluated. A significant difference in the mean parasitaemia was observed between the Vehicle, TH5487-treated, and O8-treated mice (p < 0.001). Vehicle-treated mice exhibited markedly elevated mean percentage parasitaemia and succumbed to the infection earlier than TH5487 and O8-treated mice. The O8-treated mice showed the highest parasitaemia reduction of 39.60 ± 1.53 % compared to TH5487-treated mice. Histopathological examination revealed less severe pathological features associated with P. berghei infection in mice treated with OGG1 inhibitors than in vehicle-treated malaria mice. Significant differences were observed in the sequestration of PRBC, inflammation, hemozoin deposition, and architectural loss in mice treated with O8 and TH5487 compared to untreated malaria mice. The results of this study suggested that OGG1 suppression led to a decrease in parasitaemia and severity of the histopathological features in P. berghei-infected mice. The increased survival of treated malaria mice further supported this effect. These findings indicate that OGG1 suppression could be a potential therapeutic strategy during malaria.

Targeting the 8-oxodG Base Excision Repair Pathway for Cancer Therapy

Genomic integrity is critical for cellular homeostasis, preventing the accumulation of mutations that can drive diseases such as cancer. Among the mechanisms safeguarding genomic stability, the Base Excision Repair (BER) pathway plays a pivotal role in counteracting oxidative DNA damage caused by reactive oxygen species. Central to this pathway are enzymes like 8-oxoguanine glycosylase 1 (OGG1), which recognize and excise 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) lesions, thereby initiating a series of repair processes that restore DNA integrity. BER inhibitors have recently been identified as a promising approach in cancer therapy, increasing the sensitivity of cancer cells to radiotherapy and chemotherapy. By exploiting tumor-specific DNA repair dependencies and synthetic lethal interactions, these inhibitors could be used to selectively target cancer cells while sparing normal cells. This review provides a robust reference for scientific researchers, offering an updated perspective on small-molecule inhibitors targeting the 8-oxodG-BER pathway and highlighting their potential role in expanding cancer treatment strategies.

The potential for OGG1 inhibition to be a therapeutic strategy for pulmonary diseases

INTRODUCTION

Pulmonary diseases impose a daunting burden on healthcare systems and societies. Current treatment approaches primarily address symptoms, underscoring the urgency for the development of innovative pharmaceutical solutions. A noteworthy focus lies in targeting enzymes recognizing oxidatively modified DNA bases within gene regulatory elements, given their pivotal role in governing gene expression.

AREAS COVERED

This review delves into the intricate interplay between the substrate-specific binding of 8-oxoguanine DNA glycosylase 1 (OGG1) and epigenetic regulation, with a focal point on elucidating the molecular underpinnings and their biological implications. The absence of OGG1 distinctly attenuates the binding of transcription factors to cis elements, thereby modulating pro-inflammatory or pro-fibrotic transcriptional activity. Through a synergy of experimental insights gained from cell culture studies and murine models, utilizing prototype OGG1 inhibitors (O8, TH5487, and SU0268), a promising panorama emerges. These investigations underscore the absence of cytotoxicity and the establishment of a favorable tolerance profile for these OGG1 inhibitors.

EXPERT OPINION

Thus, the strategic targeting of the active site pocket of OGG1 through the application of small molecules introduces an innovative trajectory for advancing redox medicine. This approach holds particular significance in the context of pulmonary diseases, offering a refined avenue for their management.

Targeted nuclear irradiation with a proton microbeam induces oxidative DNA base damage and triggers the recruitment of DNA glycosylases OGG1 and NTH1

DNA is the major target of radiation therapy of malignant tumors. Ionizing radiation (IR) induces a variety of DNA lesions, including chemically modified bases and strand breaks. The use of proton beam therapy for cancer treatment is ramping up, as it is expected to reduce normal tissue damage. Thus, it is important to understand the molecular mechanisms of recognition, signaling, and repair of DNA damage induced by protons in the perspective of assessing not only the risk associated with human exposure to IR but also the possibility to improve the efficacy of therapy. Here, we used targeted irradiation of nuclear regions of living cells with controlled number of protons at a high spatio-temporal resolution to detect the induced base lesions and characterize the recruitment kinetics of the specific DNA glycosylases to DNA damage sites. We show that localized irradiation with 4 MeV protons induces, in addition to DNA double strand breaks (DSBs), the oxidized bases 7,8-dihydro-8-oxoguanine (8-oxoG) and thymine glycol (TG) at the site of irradiation. Consistently, the DNA glycosylases OGG1 and NTH1, capable of excising 8-oxoG and TG, respectively, and initiating the base excision repair (BER) pathway, are recruited to the site of damage. To our knowledge, this is the first direct evidence indicating that proton microbeams induce oxidative base damage, and thus implicating BER in the repair of DNA lesions induced by protons.

Spatio-temporal dynamics of the DNA glycosylase OGG1 in finding and processing 8-oxoguanine

OGG1 is the DNA glycosylase responsible for the removal of the oxidative lesion 8-oxoguanine (8-oxoG) from DNA. The recognition of this lesion by OGG1 is a complex process that involves scanning the DNA for the presence of 8-oxoG, followed by recognition and lesion removal. Structural data have shown that OGG1 evolves through different stages of conformation onto the DNA, corresponding to elementary steps of the 8-oxoG recognition and extrusion from the double helix. Single-molecule studies of OGG1 on naked DNA have shown that OGG1 slides in persistent contact with the DNA, displaying different binding states probably corresponding to the different conformation stages. However, in cells, the DNA is not naked and OGG1 has to navigate into a complex and highly crowded environment within the nucleus. To ensure rapid detection of 8-oxoG, OGG1 alternates between 3D diffusion and sliding along the DNA. This process is regulated by the local chromatin state but also by protein co-factors that could facilitate the detection of oxidized lesions. We will review here the different methods that have been used over the last years to better understand how OGG1 detects and process 8-oxoG lesions.