The DNA-damage response (DDR) network and the immune system are significant mechanisms linked to the normal functioning of living organisms. Extensive observations suggest that agents that damage the DNA can boost immunity in various ways, some of which may be useful for immunotherapeutic applications. Indeed, the immune system can be activated by the DDR network through a number of different mechanisms, such as via (a) an increase in the tumor neoantigen burden, (b) the induction of the stimulator of interferon genes pathway, (c) the triggering of immunogenic cell death, (d) an increase in antigen presentation as a result of the augmented expression of the major histocompatibility complex type I molecule, (e) modification of the cytokine milieu in the tumor microenvironment, and (f) altered expression of the programmed cell death ligand-1. Together, the DDR network may improve the effect of immunostimulatory anticancer agents and provide a basis for devising more efficient treatment strategies, such as combinatorial therapies of DDR targeting drugs and immunomodulators. Here, the molecular mechanisms underlying the immune system’s activation by DDR are summarized, along with some of their possible uses in cancer treatment.

The DNA Damage Response (DDR) network is an essential machinery for maintaining genomic integrity, with DDR defects being implicated in cancer initiation, progression, and treatment resistance. Moreover, oxidative stress, an imbalance between reactive oxygen species production and antioxidant defense, can significantly impact cell viability, leading to cell death or survival. Herein, we tested the hypothesis that DDR-related signals and redox status measured in multiple myeloma (MM) cell lines correlate with the sensitivity to genotoxic insults. At baseline and following irradiation with Ultraviolet C (UVC; 50 J/m²) or treatment with melphalan (100 μg/mL for 5 min) DDR-related parameters, redox status expressed as GSH/GSSG ratio and apurinic/apyrimidinic sites were evaluated in a panel of eleven human MM cell lines and one healthy B lymphoblastoid cell line. We found that MM cell lines with increased apoptosis rates displayed significantly higher levels of endogenous/baseline DNA damage, reduced GSH/GSSG ratio, augmented apurinic/apyrimidinic lesions, decreased nucleotide excision repair and interstrand crosslinks repair capacities, and highly condensed chromatin structure. Taken together, these findings demonstrate that DDR-related parameters and redox status correlate with the sensitivity of MM cells to DNA-damaging agents, specifically melphalan, and, if further validated, may be exploited as novel sensitive/effective biomarkers.

Background/Objectives: Non-small cell lung cancer (NSCLC) is the most frequent type of lung cancer, and its main treatments include chemotherapy with genotoxic drugs and immunotherapy. Central to the cellular response to genotoxic stress is the DNA damage response (DDR) network, regulated by key kinases such as ataxia-telangiectasia mutated and Rad3-related (ATR). Herein, we tested the hypothesis that inhibition of ATR enhances the cytotoxicity of genotoxic agents and the antitumor immune response. Methods: DDR-related parameters and redox status, expressed as GSH/GSSG ratio, and apurinic/apyrimidinic lesions, were evaluated in human (A549, H1299) and murine (LLC) NSCLC cell lines after co-exposure to ATR inhibitor (AZD6738) and ultraviolet C (UVC) irradiation or cisplatin. Using a syngeneic LLC model, treatments of AZD6738 alone or in combination with cisplatin and/or anti-programmed cell death 1 antibody (anti-PD1) were examined. Results: In all cell lines, combined treatment with AZD6738 and cisplatin or UVC irradiation markedly decreased cell viability, DNA repair efficiency, and GSH/GSSG ratios; increased drug-induced DNA damage; and augmented apurinic/apyrimidinic lesions. In vivo, following treatment with AZD6738 and cisplatin, flow cytometry analysis performed in tumor cells revealed an increased infiltration of CD3⁺ and CD8⁺ T cells, with the triple combination of AZD6738, cisplatin, and anti-PD1 achieving the strongest antitumor effect. The CD3⁺CD4⁻CD8⁻ double-negative (DN) T cell population in tumor samples also emerged as a contributing factor in this context. Conclusions: These results demonstrate that ATR blockade concurrently enhances the efficacy of genotoxic agents and immune checkpoint inhibitors, thus paving the way for combination therapies in NSCLC.

The DNA Damage Response (DDR) network is an essential machinery for maintaining genomic integrity, with DDR defects being implicated in cancer initiation, progression and treatment resistance. Moreover, oxidative stress, an imbalance between reactive oxygen species production and antioxidant defence, can significantly impact cell viability, leading to cell death or survival. Herein, we tested the hypothesis that DDR-related signals and oxidative stress status measured in multiple myeloma (MM) cell lines correlate with the sensitivity to genotoxic insults. In a panel of eleven human MM cell lines and one healthy B lymphoblastoid cell line, oxidative stress, apurinic/apyrimidinic sites and DDR-related parameters, including endogenous/baseline DNA damage, critical DNA repair mechanisms, chromatin condensation and apoptosis rates were evaluated. We found that MM cell lines with increased apoptosis rates displayed significantly higher levels of endogenous/baseline DNA damage, increased oxidative stress and apurinic/apyrimidinic lesions, decreased nucleotide excision repair and interstrand crosslinks repair capacities and highly condensed chromatin structure. Taken together, these findings demonstrate that DDR-related parameters and redox status correlate with the sensitivity of MM cells to DNA damaging agents and, if further validated, may be exploited as novel therapeutic targets and sensitive/effective biomarkers.

Background/Objectives: Disruption of cellular redox balance and DNA damage response (DDR) signals represents a key driver of cancer development, influencing tumor progression and therapeutic response. Here, we investigated the interplay between DDR-related parameters and oxidative stress in relation to treatment response in patients with multiple myeloma (MM). Methods: Oxidative stress and DDR signals were evaluated in primary cells, including peripheral blood mononuclear cells (PBMCs) and bone marrow plasma cells (BMPCs), collected at diagnosis from MM patients who were subsequently classified as responders (n = 35) or non-responders (n = 41) to melphalan-based therapy. Results: PBMCs and BMPCs from non-responders exhibited a distinct biological profile characterized by lower baseline DNA damage, reduced oxidative stress, increased nucleotide excision repair and double-strand break repair capacity, and reduced apoptotic sensitivity compared with responders (all p < 0.001). In addition, non-responders displayed increased chromatin relaxation. Differential gene expression patterns involving DDR-related pathways further distinguished BMPCs between the two clinical outcome groups. Conclusions: Collectively, these findings indicate that alterations in oxidative stress and DDR signals play a crucial role in determining response to melphalan-based therapy in MM. The identification of these molecular alterations in an easily accessible tissue, such as peripheral blood, underscores their potential clinical relevance and warrants further validation.

Alterations in the redox status and the DNA damage response (DDR) parameters are early, mechanistically interconnected drivers of carcinogenesis. Herein, we investigated whether such alterations, arising during the progression of Multiple Myeloma (MM), are systemically reflected in peripheral blood mononuclear cells (PBMCs). Redox status, expressed as the GSH/GSSG ratio, and DDR-related parameters, including baseline DNA damage, efficiency of key DNA repair pathways, namely nucleotide excision repair (NER) and double-strand break repair (DSB/R), as well as apoptotic sensitivity, were evaluated in PBMCs from 17 patients with Monoclonal Gammopathy of Undetermined Significance (MGUS), 20 with smoldering MM (SMM), and 19 with MM. PBMCs from 20 healthy controls (HCs) were analyzed in parallel. Baseline DNA damage levels and DNA repair capacities across all examined pathways increased progressively in the following order: HC < MGUS < SMM < MM (p < 0.001). This progression was accompanied by a gradual increase in chromatin relaxation. Conversely, the GSH/GSSG ratio and apoptotic sensitivity declined during disease progression (p < 0.001). Collectively, malignant transformation in MM is associated with progressive dysregulation of DDR pathways and redox status in PBMCs. The identification of these molecular perturbations in an easily accessible tissue, such as peripheral blood, underscores their potential utility for early detection and prognostic assessment of MM.