DNA damage response signaling pathways and targets for radiotherapy sensitization in cancer

CDC20 promotes radioresistance of prostate cancer by activating Twist1 expression

Currently, radiotherapy is one of the most attractive treatments for prostate cancer (PCa) patients. However, radioresistance remains a challenging issue and the underlying mechanism is unknown. Growing evidence has demonstrated that CDC20 (Cell division cycle protein 20) plays a pivotal role in a variety of tumors, including PCa. Here, GEPIA database mining and western blot analysis showed that higher expression of CDC20 was observed in PCa tissues and cells. We demonstrated that the expression of CDC20 was increased in PCa cells by irradiation, and knockdown of CDC20 resulted in inhibition of cell proliferation, migration, tumor formation, induced cell apoptosis and increased radiosensitivity in PCa in vitro and in vivo. Furthermore, we observed that CDC20 regulated Twist1 pathway, influencing cell proliferation and migration. These results suggest that targeting CDC20 and Twist1 may be an effective way to improve the radiosensitivity of PCa.

The relationship between BCG immunotherapy and oxidative stress parameters in patients with nonmuscle invasive bladder cancer

INTRODUCTION

Environmental chemicals have been associated with the regulation of oxidative stress markers, which have the potential for the development of bladder cancer. However, limited studies on the function of oxidative stress parameters and nonmuscle invasive bladder cancer (NMIBC) in therapy response are available. Here we studied the oxidative stress parameters in response to BCG immunotherapy in NMIBC patients.

MATERIAL AND METHODS

A total of 120 patients with NMIBC and treatment with BCG were enrolled and categorized into 2 groups on BCG response, 50 patients were BCG-responsive (BCG-R) and 70 were BCG-nonresponsive (BCG-N). BCG-R have no evidence of tumor recurrence or advancement after 1 year of BCG immunotherapy, but BCG-N has a recurrence of tumor after 3 to 6 months cycles of BCG instillation, as determined by cystoscopy. In all groups, we measured the levels of oxidative stress markers- malondialdehyde (MDA), nitric oxide (NO), superoxide dismutase (SOD), and catalase (CAT).

RESULTS

The levels of oxidative stress markers viz. MDA, NO, and SOD in the BCG-N group were significantly higher (P < 0.001) than in the BCG-R group. Furthermore, the data demonstrated a significant correlation between oxidative stress marker and NMIBC T1 high grade and tumor size >2.5 cm. However, no statistically significant difference was found between studied groups with CAT.

CONCLUSION

The findings suggest that the carcinogenesis of NMIBC is associated with oxidative damage of biomolecules and indicates the involvement of oxidative stress markers in the development and recurrence of NMIBC.; Therefore, it is critical to ensure the management for T1 high grade and tumor size of >2.5 cm for antioxidant protection.

Silver Nanoparticles (AgNPs) as Enhancers of Everolimus and Radiotherapy Sensitivity on Clear Cell Renal Cell Carcinoma

Nanomedicine's advent has promised to revolutionize different biomedical fields, including oncology. Silver Nanoparticles (AgNPs) showed promising results in different tumor models. Clear cell Renal Cell Carcinoma (ccRCC) is especially challenging due to its late diagnosis, poor prognosis and treatment resistance. Therefore, defining new therapeutic targets and regimens could improve patient management. This study intends to evaluate AgNPs' effect in ccRCC cells and explore their potential combinatory effect with Everolimus and Radiotherapy. AgNPs were synthesized, and their effect was evaluated regarding their entering pathway, cellular proliferation capacity, ROS production, mitochondrial membrane depolarization, cell cycle analysis and apoptosis assessment. AgNPs were combined with Everolimus or used to sensitize cells to radiotherapy. AgNPs are cytotoxic to 786-O cells, a ccRCC cell line, entering through endocytosis, increasing ROS, depolarizing mitochondrial membrane, and blocking the cell cycle, leading to a reduction of proliferation capacity and apoptosis. Combined with Everolimus, AgNPs reduce cell viability and inhibit proliferation capacity. Moreover, 786-O is intrinsically resistant to radiation, but after AgNPs' administration, radiation induces cytotoxicity through mitochondrial membrane depolarization and S phase blockage. These results demonstrate AgNPs' cytotoxic potential against ccRCC and seem promising regarding the combination with Everolimus and sensitization to radiotherapy, which can, in the future, benefit ccRCC patients' management.

RMI1 facilitates repair of ionizing radiation-induced DNA damage and maintenance of genomic stability

Ionizing radiation (IR) causes a wide variety of DNA lesions, of which DNA double-stranded breaks (DSBs) are the most deleterious. Homologous recombination (HR) is a crucial route responsible for repairing DSBs. RecQ-mediated genome instability protein 1 (RMI1) is a member of an evolutionarily conserved Bloom syndrome complex, which prevents and resolves aberrant recombination products during HR, thereby promoting genome stability. However, little is known about the role of RMI1 in regulating the cellular response to IR. This study aimed to understand the cellular functions and molecular mechanisms by which RMI1 maintains genomic stability after IR exposure. Here, we showed IR upregulated the RMI1 protein level and induced RMI1 relocation to the DNA damage sites. We also demonstrated that the loss of RMI1 in cells resulted in enhanced levels of DNA damage, sustained cell cycle arrest, and impaired HR repair after IR, leading to reduced cell viability and elevated genome instability. Taken together, our results highlighted the direct roles of RMI1 in response to DNA damage induced by IR and implied that RMI1 might be a new genome safeguard molecule to radiation-induced damage.

Radiation-induced gastric injury during radiotherapy: molecular mechanisms and clinical treatment

Radiotherapy (RT) has been the standard of care for treating a multitude of cancer types. Radiation-induced gastric injury (RIGI) is a common complication of RT for thoracic and abdominal tumors. It manifests acutely as radiation gastritis or gastric ulcers, and chronically as chronic atrophic gastritis or intestinal metaplasia. In recent years, studies have shown that intracellular signals such as oxidative stress response, p38/MAPK pathway and transforming growth factor-β signaling pathway are involved in the progression of RIGI. This review also summarized the risk factors, diagnosis and treatment of this disease. However, the root of therapeutic challenges lies in the incomplete understanding of the mechanisms. Here, we also highlight the potential mechanistic, diagnostic and therapeutic directions of RIGI.

Genomic and Transcriptomic Remodeling by Neoadjuvant Chemoradiotherapy (nCRT) and the Indicative Role of Acquired INDEL Percentage for nCRT Efficacy in Esophageal Squamous Cell Carcinoma

PURPOSE

The effect of genomic factors on the response of patients with esophageal squamous cell carcinoma (ESCC) to neoadjuvant chemoradiotherapy (nCRT), as well as how nCRT influences the genome and transcriptome of ESCC, remain largely unknown.

METHODS AND MATERIALS

In total, 137 samples from 57 patients with ESCC undergoing nCRT were collected and subjected to whole-exome sequencing and RNA sequencing analysis. Genetic and clinicopathologic factors were compared between the patients achieving pathologic complete response and patients not achieving pathologic complete response. Genomic and transcriptomic profiles before and after nCRT were analyzed.

RESULTS

Codeficiency of the DNA damage repair and HIPPO pathways synergistically sensitized ESCC to nCRT. nCRT induced small INDELs and focal chromosomal loss concurrently. Acquired INDEL% exhibited a decreasing trend with the increase of tumor regression grade (P = .06, Jonckheere's test). Multivariable Cox analysis indicated that higher acquired INDEL% was associated with better survival (adjusted hazard ratio [aHR], 0.93; 95% CI, 0.86-1.01; P = .067 for recurrence-free survival [RFS]; aHR, 0.86; 95% CI, 0.76-0.98; P = .028 for overall survival [OS], with 1% of acquired INDEL% as unit). The prognostic value of acquired INDEL% was confirmed by the Glioma Longitudinal AnalySiS data set (aHR, 0.95; 95% CI, 0.902-0.997; P = .037 for RFS; aHR, 0.96; 95% CI, 0.917-1.004; P = .076 for OS). Additionally, clonal expansion degree was negatively associated with patient survival (aHR, 5.87; 95% CI, 1.10-31.39; P = .038 for RFS; aHR, 9.09; 95% CI, 1.10-75.36; P = .041 for OS, with low clonal expression group as reference) and also negatively correlated with acquired INDEL% (Spearman ρ = -0.45; P = .02). The expression profile was changed after nCRT. The DNA replication gene set was downregulated, while the cell adhesion gene set was upregulated after nCRT. Acquired INDEL% was negatively correlated with the enrichment of the DNA replication gene set (Spearman ρ = -0.56; P = .003) but was positively correlated with the enrichment of the cell adhesion gene set (Spearman ρ = 0.40; P = .05) in posttreatment samples.

CONCLUSIONS

nCRT remodels the genome and transcriptome of ESCC. Acquired INDEL% is a potential biomarker to indicate the effectiveness of nCRT and radiation sensitivity.

Role of exosomes in metastasis and therapeutic resistance in esophageal cancer

Esophageal cancer (EC) has a high incidence and mortality rate and is emerging as one of the most common health problems globally. Owing to the lack of sensitive detection methods, uncontrollable rapid metastasis, and pervasive treatment resistance, EC is often diagnosed in advanced stages and is susceptible to local recurrence. Exosomes are important components of intercellular communication and the exosome-mediated crosstalk between the cancer and surrounding cells within the tumor microenvironment plays a crucial role in the metastasis, progression, and therapeutic resistance of EC. Considering the critical role of exosomes in tumor pathogenesis, this review focused on elucidating the impact of exosomes on EC metastasis and therapeutic resistance. Here, we summarized the relevant signaling pathways involved in these processes. In addition, we discussed the potential clinical applications of exosomes for the early diagnosis, prognosis, and treatment of EC.

Haberlea rhodopensis Extract Tunes the Cellular Response to Stress by Modulating DNA Damage, Redox Components, and Gene Expression

Ionizing radiation (IR) and reactive oxygen species (ROS)-induced oxidative stress can cause damage to cellular biomolecules, including DNA, proteins, and lipids. These harmful effects can compromise essential cellular functions and significantly raise the risk of metabolic dysfunction, accumulation of harmful mutations, genome instability, cancer, accelerated cellular senescence, and even death. Here, we present an investigation of HeLa cancer cells' early response to gamma IR (γ-IR) and oxidative stress after preincubation of the cells with natural extracts of the resurrection plant Haberlea rhodopensis. In light of the superior protection offered by plant extracts against radiation and oxidative stress, we investigated the cellular defence mechanisms involved in such protection. Specifically, we sought to evaluate the molecular effects of H. rhodopensis extract (HRE) on cells subjected to genotoxic stress by examining the components of the redox pathway and quantifying the transcription levels of several critical genes associated with DNA repair, cell cycle regulation, and apoptosis. The influence of HRE on genome integrity and the cell cycle was also studied via comet assay and flow cytometry. Our findings demonstrate that HREs can effectively modulate the cellular response to genotoxic and oxidative stress within the first two hours following exposure, thereby reducing the severity of such stress. Furthermore, we observed the specificity of genoprotective HRE doses depending on the source of the applied genotoxic stress.

The role of N6-methyladenosine RNA modification in platinum resistance

N6-methyladenosine (m6A) RNA methylation, a dynamic regulator of transcript expression, plays a pivotal role in cancer by influencing diverse mRNA processes, including nuclear export, splicing, translation and decay. It intersects with cancer biology, impacting progression, treatment sensitivity and prognosis. Platinum-based compounds are essential in cancer treatment, while intrinsic or acquired resistance poses a formidable challenge, limiting therapeutic efficacy. Recent breakthroughs have established a direct association between m6A RNA methylation and platinum resistance in various cancer types. This review summarized related studies, aiming to provide profound insights into the interplay between m6A-associated regulation and platinum-resistance mechanisms in cancer. It explores therapeutic approaches, including personalized treatments based on m6A profiles, guiding future research to enhance clinical strategies for oncological prognostic outcomes.

Wogonin Diminishes Radioresistance of Breast Cancer via Inhibition of the Nrf2/HIF-1[Formula: see text] Pathway

Radiotherapy plays a crucial role in the multimodal treatment of breast cancer. However, radioresistance poses a significant challenge to its effectiveness, hindering successful cancer therapy. Emerging evidence indicates that Nrf2 and HIF-1[Formula: see text] are critical regulators of cellular anti-oxidant responses and that their overexpression significantly promotes radioresistance. Wogonin (WG), the primary component isolated from Scutellaria baicalensis, exhibits potential antitumor and reversal of multidrug resistance activities. Nevertheless, the role of WG in radioresistance remains unclear. This study aims to explore the effects of WG on the radioresistance of breast cancer. Our results indicate that Nrf2 and HIF-1[Formula: see text] overexpression was observed in breast cancer tissues and was correlated with the histological grading of the disease. Radiation further increased the levels of Nrf2 and HIF-1[Formula: see text] in breast cancer cells. However, WG demonstrated the ability to induce cell apoptosis and reverse radioresistance by inhibiting the Nrf2/HIF-1[Formula: see text] pathway. These effects were also confirmed in xenograft mice models. Mechanistically, WG enhanced the level of the Nrf2 inhibitor Keap1 through reducing CpG methylation in the promoter region of the Keap1 gene. Consequently, the Nrf2/HIF-1[Formula: see text] pathway, along with the Nrf2- and HIF-1[Formula: see text]-dependent protective responses, were suppressed. Taken together, our findings demonstrate that WG can epigenetically regulate the Keap1 gene, inhibit the Nrf2/HIF-1[Formula: see text] pathway, induce apoptosis in breast cancer cells, and diminish acquired radioresistance. This study offers potential strategies to overcome the limitations of current radiotherapy for breast cancer.

PARP inhibitors combined with radiotherapy: are we ready?

PARP was an enzyme found in the nucleus of eukaryotic cells that played a crucial role in repairing damaged DNA. Recently, PARP inhibitors have demonstrated great potential in cancer treatment. Thus, the FDA has approved several small-molecule PARP inhibitors for cancer maintenance therapy. The combination of PARP inhibitors and radiotherapy relies on synthetic lethality, taking advantage of the flaws in DNA repair pathways to target cancer cells specifically. Studies conducted prior to clinical trials have suggested that the combination of PARP inhibitors and radiotherapy can enhance the sensitivity of cancer cells to radiation, intensify DNA damage, and trigger cell death. Combining radiotherapy with PARP inhibitors in clinical trials has enhanced the response rate and progression-free survival of diverse cancer patients. The theoretical foundation of PARP inhibitors combined with radiotherapy is explained in detail in this article, and the latest advances in preclinical and clinical research on these inhibitors for tumor radiotherapy are summarized. The problems in the current field are recognized in our research and potential therapeutic applications for tumors are suggested. Nevertheless, certain obstacles need to be tackled when implementing PARP inhibitors and radiotherapies in clinical settings. Factors to consider when using the combination therapy are the most suitable schedule and amount of medication, identifying advantageous candidates, and the probable adverse effects linked with the combination. The combination of radiotherapy and PARP inhibitors can greatly enhance the effectiveness of cancer treatment.

AZD-7648, a DNA-PK Inhibitor, Induces DNA Damage, Apoptosis, and Cell Cycle Arrest in Chronic and Acute Myeloid Leukemia Cells

The non-homologous end joining pathway is vital for repairing DNA double-strand breaks (DSB), with DNA-dependent protein kinase (DNA-PK) playing a critical role. Altered DNA damage response (DDR) in chronic (CML) and acute myeloid leukemia (AML) offers potential therapeutic opportunities. We studied the therapeutic potential of AZD-7648 (DNA-PK inhibitor) in CML and AML cell lines. This study used two CML (K-562 and LAMA-84) and five AML (HEL, HL-60, KG-1, NB-4, and THP-1) cell lines. DDR gene mutations were obtained from the COSMIC database. The copy number and methylation profile were evaluated using MS-MLPA and DDR genes, and telomere length using qPCR. p53 protein expression was assessed using Western Blot, chromosomal damage through cytokinesis-block micronucleus assay, and γH2AX levels and DSB repair kinetics using flow cytometry. Cell density and viability were analyzed using trypan blue assay after treatment with AZD-7648 in concentrations ranging from 10 to 200 µM. Cell death, cell cycle distribution, and cell proliferation rate were assessed using flow cytometry. The cells displayed different DNA baseline damage, DDR gene expressions, mutations, genetic/epigenetic changes, and p53 expression. Only HEL cells displayed inefficient DSB repair. The LAMA-84, HEL, and KG-1 cells were the most sensitive to AZD-7648, whereas HL-60 and K-562 showed a lower effect on density and viability. Besides the reduction in cell proliferation, AZD-7648 induced apoptosis, cell cycle arrest, and DNA damage. In conclusion, these results suggest that AZD-7648 holds promise as a potential therapy for myeloid leukemias, however, with variations in drug sensitivity among tested cell lines, thus supporting further investigation to identify the specific factors influencing sensitivity to this DNA-PK inhibitor.

Epigenetic regulation of TP53 is involved in prostate cancer radioresistance and DNA damage response signaling

External beam radiotherapy (RT) is a leading first-line therapy for prostate cancer (PCa), and, in recent years, significant advances have been accomplished. However, RT resistance can arise and result in long-term recurrence or disease progression in the worst-case scenario. Thus, making crucial the discovery of new targets for PCa radiosensitization. Herein, we generated a radioresistant PCa cell line, and found p53 to be highly expressed in radioresistant PCa cells, as well as in PCa patients with recurrent/disease progression submitted to RT. Mechanism dissection revealed that RT could promote p53 expression via epigenetic modulation. Specifically, a decrease of H3K27me3 occupancy at TP53 gene promoter, due to increased KDM6B activity, was observed in radioresistant PCa cells. Furthermore, p53 is essential for efficient DNA damage signaling response and cell recovery upon stress induction by prolonged fractionated irradiation. Remarkably, KDM6B inhibition by GSK-J4 significantly decreased p53 expression, consequently attenuating the radioresistant phenotype of PCa cells and hampering in vivo 3D tumor formation. Overall, this work contributes to improve the understanding of p53 as a mediator of signaling transduction in DNA damage repair, as well as the impact of epigenetic targeting for PCa radiosensitization.

Advancement in precision diagnosis and therapeutic for triple-negative breast cancer: Harnessing diagnostic potential of CRISPR-cas & engineered CAR T-cells mediated therapeutics

Cancer is characterized by uncontrolled cell growth, disrupted regulatory pathways, and the accumulation of genetic mutations. These mutations across different types of cancer lead to disruptions in signaling pathways and alterations in protein expression related to cellular growth and proliferation. This review highlights the AKT signaling cascade and the retinoblastoma protein (pRb) regulating cascade as promising for novel nanotheranostic interventions. Through synergizing state-of-the-art gene editing tools like the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-Cas system with nanomaterials and targeting AKT, there is potential to enhance cancer diagnostics significantly. Furthermore, the integration of modified CAR-T cells into multifunctional nanodelivery systems offers a promising approach for targeted cancer inhibition, including the eradication of cancer stem cells (CSCs). Within the context of highly aggressive and metastatic Triple-negative Breast Cancer (TNBC), this review specifically focuses on devising innovative nanotheranostics. For both pre-clinical and post-clinical TNBC detection, the utilization of the CRISPR-Cas system, guided by RNA (gRNA) and coupled with a fluorescent reporter specifically designed to detect TNBC's mutated sequence, could be promising. Additionally, a cutting-edge approach involving the engineering of TNBC-specific iCAR and syn-Notch CAR T-cells, combined with the co-delivery of a hybrid polymeric nano-liposome encapsulating a conditionally replicative adenoviral vector (CRAdV) against CSCs, could present an intriguing intervention strategy. This review thus paves the way for exciting advancements in the field of nanotheranostics for the treatment of TNBC and beyond.

A Boolean model of the oncogene role of FAM111B in lung adenocarcinoma

The ultimate goal of this study is to analyze the gene regulation between FAM111B and p53 in lung adenocarcinoma using Boolean networks. Recent studies have shown that downregulation of FAM111B enhances the G2/M cell cycle checkpoint in the respective cell lines. Upregulation of p53 directly downregulates FAM111B, which is directed to affect cell cycle controllers Cdc25C and Cdk1/CyclinB, thereby controlling G2/M cell cycle arrest. As for apoptosis, down-regulation of FAM111B by p53 directly regulates the BAG3/Bcl-2 axis, which triggers apoptotic cell death. However, the molecular mechanisms involving p53 and FAM111B in G2/M checkpoint regulation are still unknown. Thus, we present a Boolean model of the G2/M checkpoint considering the effect of p53 and FAM111B. Our model indicates that the cell fate between the two cellular phenotypes, arrest, and apoptosis, at the G2/M checkpoint is non-deterministic and is controlled by p53. The model was compared with the experimental data involving gain- or loss-of-function genes and achieved a fair agreement. The model predicts a positive circuit involving p53/FAM111B/BAG3. Our circuit perturbation analysis suggests that this circuit may be essential for controlling cell-fate decisions at the G2/M checkpoint. Our model supports that FAM111B is an engaging target for drug development in lung adenocarcinoma.

Post-radiation treatment of 3,3'-diselenodipropionic acid augments cell kill by modulating DNA repair and cell migration pathways in A549 cells

Aim of the present study was to test whether ionizing radiation (IR) treatment along with 3,3'-diselenodipropionic acid (DSePA), a redox active organodiselenide achieved better tumor control by suppressing the growth and migration of lung cancer cells. The results indicated that post-IR (2 Gy) treatment of DSePA (5 μM) led to a significantly higher cell death as compared to that of DSePA and IR treatments separately. Importantly, combinatorial treatment also showed reduction in the proportion of cancer stem cells and the clonogenic survival of A549 cells. The mechanistic studies indicated that combinatorial treatment although exhibited reductive environment (marked by decrease in ROS and increase of GSH/GSSG) at early time points (2-6 h postradiation), slowed DNA repair, inhibited epithelial-mesenchymal transition (EMT)/cell migration and induced significant level of apoptosis. DSePA mediated suppression of ATM/DNAPKs/p53 (DNA damage response signaling) and Akt/G-CSF (EMT) pathways appeared to be the major mechanism responsible for its radio-modulating activity. Finally, the combined treatment of IR (2 Gy × 4) and DSePA (0.1-0.25 mg/kg body weight daily through oral gavage) showed a significantly higher tumor suppression of the A549 xenograft as compared to that of DSePA and IR treatments separately in the mouse model. In conclusion, post-IR treatment of DSePA augmented cell kill by inhibiting DNA repair and cell migration in A549 cells.

Double-strand DNA break repair: molecular mechanisms and therapeutic targets

Double-strand break (DSB), a significant DNA damage brought on by ionizing radiation, acts as an initiating signal in tumor radiotherapy, causing cancer cells death. The two primary pathways for DNA DSB repair in mammalian cells are nonhomologous end joining (NHEJ) and homologous recombination (HR), which cooperate and compete with one another to achieve effective repair. The DSB repair mechanism depends on numerous regulatory variables. DSB recognition and the recruitment of DNA repair components, for instance, depend on the MRE11-RAD50-NBS1 (MRN) complex and the Ku70/80 heterodimer/DNA-PKcs (DNA-PK) complex, whose control is crucial in determining the DSB repair pathway choice and efficiency of HR and NHEJ. In-depth elucidation on the DSB repair pathway's molecular mechanisms has greatly facilitated for creation of repair proteins or pathways-specific inhibitors to advance precise cancer therapy and boost the effectiveness of cancer radiotherapy. The architectures, roles, molecular processes, and inhibitors of significant target proteins in the DSB repair pathways are reviewed in this article. The strategy and application in cancer therapy are also discussed based on the advancement of inhibitors targeted DSB damage response and repair proteins.

Evolving role of novel radiosensitizers and immune checkpoint inhibitors in (chemo)radiotherapy of locally advanced head and neck squamous cell carcinoma

Chemoradiotherapy (CRT) remains the standard treatment for locally advanced head and neck squamous cell carcinoma (LA-HNSCC), based on numerous randomized controlled trials and meta-analyses demonstrating that CRT improved locoregional control and overall survival. Achieving locoregional control is a crucial outcome for the treatment of HNSCC, as it directly affects patient quality of life and survival. Cisplatin is the recommended standard-of-care radiosensitizing agent for LA-HNSCC patients undergoing CRT, whereas cetuximab-radiotherapy is reserved for cisplatin-ineligible patients. Immune checkpoint inhibitors (ICIs) have shown promise in the treatment of recurrent or metastatic HNSCC. However, the combination of ICIs with standard-of-care radiotherapy or chemoradiotherapy in LA-HNSCC has not demonstrated significant improvement in survivals. Over the past few decades, significant advancements in radiotherapy techniques have allowed for more precise and effective radiation delivery while minimizing toxicity to surrounding normal tissues. These advances have led to improved treatment outcomes and quality of life for patients with LA-HNSCC. Despite these advancements, the development of novel radiosensitizing agents remains an unmet need. This review discusses the mechanism of radiotherapy and its impact on the immune system. We summarize the latest clinical development of novel radiosensitizing agents, such as SMAC mimetics, DDR pathway inhibitors, and CDK4/6 inhibitor. We also elucidate the emerging evidence of combining ICIs with radiotherapy or chemoradiotherapy in curative settings for LA-HNSCC, using both concurrent and sequential approaches. Lastly, we discuss the future direction of systemic therapy in combination with radiotherapy in treatment for LA-HNSCC.

Cyclin D1 promotes radioresistance through regulation of RAD51 in melanoma

Melanoma is a notoriously radioresistant type of skin cancer. Elucidation of the specific mechanisms underlying radioresistance is necessary to improve the clinical efficacy of radiation therapy. To identify the key factors contributing to radioresistance, five melanoma cell lines were selected for study and genes that were upregulated in relatively radioresistant melanomas compared with radiosensitive melanoma cells determined via RNA sequencing technology. In particular, we focused on cyclin D1 (CCND1), a well known cell cycle regulatory molecule. In radiosensitive melanoma, overexpression of cyclin D1 reduced apoptosis. In radioresistant melanoma cell lines, suppression of cyclin D1 with a specific inhibitor or siRNA increased apoptosis and decreased cell proliferation in 2D and 3D spheroid cultures. In addition, we observed increased expression of γ-H2AX, a molecular marker of DNA damage, even at a later time after γ-irradiation, under conditions of inhibition of cyclin D1, with a response pattern similar to that of radiosensitive SK-Mel5. In the same context, expression and nuclear foci formation of RAD51, a key enzyme for homologous recombination (HR), were reduced upon inhibition of cyclin D1. Downregulation of RAD51 also reduced cell survival to irradiation. Overall, suppression of cyclin D1 expression or function led to reduced radiation-induced DNA damage response (DDR) and triggered cell death. Our collective findings indicate that the presence of increased cyclin D1 potentially contributes to the development of radioresistance through effects on RAD51 in melanoma and could therefore serve as a therapeutic target for improving the efficacy of radiation therapy.

Estimated Prevalence, Tumor Spectrum, and Neurofibromatosis Type 1-Like Phenotype of CDKN2A-Related Melanoma-Astrocytoma Syndrome

Importance

Knowledge about the prevalence and tumor types of CDKN2A-related melanoma-astrocytoma syndrome (MAS) is limited and could improve disease recognition.

Objective

To estimate the prevalence and describe the tumor types of MAS.

Design, Setting, and Participants

This retrospective cohort study analyzed all available MAS cases from medical centers in the US (2 sites) and Europe (2 sites) and from biomedical population genomic databases (UK Biobank [United Kingdom], Geisinger MyCode [US]) between January 1, 1976, and December 31, 2020. Patients with MAS with CDKN2A germline pathogenic variants and 1 or more neural tumors were included. Data were analyzed from June 1, 2022, to January 31, 2023.

Main Outcomes and Measures

Disease prevalence and tumor frequency.

Results

Prevalence of MAS ranged from 1 in 170 503 (n = 1 case; 95% CI, 1:30 098-1:965 887) in Geisinger MyCode (n = 170 503; mean [SD] age, 58.9 [19.1] years; 60.6% women; 96.2% White) to 1 in 39 149 (n = 12 cases; 95% CI, 1:22 396-1:68 434) in UK Biobank (n = 469 789; mean [SD] age, 70.0 [8.0] years; 54.2% women; 94.8% White). Among UK Biobank patients with MAS (n = 12) identified using an unbiased genomic ascertainment approach, brain neoplasms (4 of 12, 33%; 1 glioblastoma, 1 gliosarcoma, 1 astrocytoma, 1 unspecified type) and schwannomas (3 of 12, 25%) were the most common malignant and benign neural tumors, while cutaneous melanoma (2 of 12, 17%) and head and neck squamous cell carcinoma (2 of 12, 17%) were the most common nonneural malignant neoplasms. In a separate case series of 14 patients with MAS from the US and Europe, brain neoplasms (4 of 14, 29%; 2 glioblastomas, 2 unspecified type) and malignant peripheral nerve sheath tumor (2 of 14, 14%) were the most common neural cancers, while cutaneous melanoma (4 of 14, 29%) and sarcomas (2 of 14, 14%; 1 liposarcoma, 1 unspecified type) were the most common nonneural cancers. Cutaneous neurofibromas (7 of 14, 50%) and schwannomas (2 of 14, 14%) were also common. In 1 US family, a father and son with MAS had clinical diagnoses of neurofibromatosis type 1 (NF1). Genetic testing of the son detected a pathogenic CDKN2A splicing variant (c.151-1G>C) and was negative for NF1 genetic alterations. In UK Biobank, 2 in 150 (1.3%) individuals with clinical NF1 diagnoses had likely pathogenic variants in CDKN2A, including 1 individual with no detected variants in the NF1 gene.

Conclusions and Relevance

This cohort study estimates the prevalence and describes the tumors of MAS. Additional studies are needed in genetically diverse populations to further define population prevalence and disease phenotypes.

Combining Radiotherapy with Immunotherapy in Cervical Cancer: Where Do We Stand and Where Are We Going?

OPINION STATEMENT

Combining immunotherapy and radiotherapy as a treatment strategy for cervical cancer has attracted increasing attention. The primary objective of this review is to provide an up-to-date summary of the knowledge regarding the combined use of radiotherapy and immunotherapy for treating cervical cancer. This review discusses the biological rationale combining immunotherapy with radiotherapy in a clinical setting and presents supporting evidence for the combination strategy based on both safety and effectiveness data. Additionally, we discuss the potential and challenges of combining radiotherapy and immunotherapy in clinical practice.

Update on Radiotherapy Changes of Nasopharyngeal Carcinoma Tumor Microenvironment

The utilization of radiotherapy (RT) serves as the principal approach for managing nasopharyngeal carcinoma (NPC). Consequently, it is imperative to investigate the correlation between the radiation microenvironment and radiation resistance in NPC. PubMed and China National Knowledge Infrastructure (CNKI) databases were accessed to perform a search utilizing the English keywords "nasopharyngeal cancer", "radiotherapy", and "microenvironment". The search time spanned from the establishment of the database until January 20, 2023. A total of 82 articles were included. The post-radiation tumor microenvironment (TME), or the radiation microenvironment, includes several components, such as the radiation-immune microenvironment and the radiation-hypoxic microenvironment. The radiation-immune microenvironment includes various factors like immune cells, signaling molecules, and extracellular matrix. RT can reshape the TME, leading to immune responses with both cytotoxic effects (T cells, B cells, natural killer (NK) cells) and immune escape mechanisms (regulatory T cells (Tregs), macrophages). RT enhances immune responses through DNA release, type I interferons, and immune cell recruitment. Radiation-hypoxic microenvironment affects metabolism and molecular changes. RT-induced hypoxia causes vascular changes, fibrosis, and vessel compression, leading to tissue hypoxia. Hypoxia activates hypoxia-inducible factor (HIF)-1α/2α, promoting angiogenesis and glycolysis in tumor cells. TME changes due to hypoxia also involve immune suppressive cells like myeloid-derived suppressor cells (MDSCs), tumor-associated macrophages (TAMs), and Tregs. The radiation microenvironment is involved in radiation resistance and holds a significant effect on the prognosis of patients with NPC. Exploring the radiation microenvironment provides new insights into RT and NPC research.

Iron Oxide Nanoparticles in Cancer Treatment: Cell Responses and the Potency to Improve Radiosensitivity

The main concept of radiosensitization is making the tumor tissue more responsive to ionizing radiation, which leads to an increase in the potency of radiation therapy and allows for decreasing radiation dose and the concomitant side effects. Radiosensitization by metal oxide nanoparticles is widely discussed, but the range of mechanisms studied is not sufficiently codified and often does not reflect the ability of nanocarriers to have a specific impact on cells. This review is focused on the magnetic iron oxide nanoparticles while they occupied a special niche among the prospective radiosensitizers due to unique physicochemical characteristics and reactivity. We collected data about the possible molecular mechanisms underlying the radiosensitizing effects of iron oxide nanoparticles (IONPs) and the main approaches to increase their therapeutic efficacy by variable modifications.

Epigenetics as a determinant of radiation response in cancer

Radiation therapy is a cornerstone of modern cancer treatment. Treatment is based on depositing focal radiation to the tumor to inhibit cell growth, proliferation and metastasis, and to promote the death of cancer cells. In addition, radiation also affects non-tumor cells in the tumor microenvironmental (TME). Radiation resistance of the tumor cells is the most common cause of treatment failure, allowing survival of cancer cell and subsequent tumor growing. Molecular radioresistance comprises genetic and epigenetic characteristics inherent in cancer cells, or characteristics acquired after exposure to radiation. Furthermore, cancer stem cells (CSCs) and non-tumor cells into the TME as stromal and immune cells have a role in promoting and maintaining radioresistant tumor phenotypes. Different regulatory molecules and pathways distinctive of radiation resistance include DNA repair, survival signaling and cell death pathways. Epigenetic mechanisms are one of the most relevant events that occur after radiotherapy to regulate the expression and function of key genes and proteins in the differential radiation-response. This article reviews recent data on the main molecular mechanisms and signaling pathways related to the biological response to radiotherapy in cancer; highlighting the epigenetic control exerted by DNA methylation, histone marks, chromatin remodeling and m6A RNA methylation on gene expression and activation of signaling pathways related to radiation therapy response.

Genes Involved in DNA Damage Cell Pathways and Health of the Oldest-Old (85+)

Some sources report a connection of cellular senescence with chronic pathological conditions; however, the association between particular cellular processes and general health is rarely examined. This study aims to test the relationship of general health with DNA damage pathways that play a crucial role in senescence. The association of ten selected SNPs with subjective and objective general health and functional ability indicators has been tested in 314 oldest-old people from Croatia. Multivariate logistic regression was employed to simultaneously test the impact of variables potentially influencing targeted health and functional ability variables. The best model, explaining 37.1% of the variance, has six independent significant predictors of functional ability scores: rs16847897 in TERC, rs533984 in MRE11A, and rs4977756 in CDKN2B, chronic disease count, Mini-Mental State Examination scores, and age at surveying. In conclusion, the examined ten loci involved in DNA damage repair pathways showed a more significant association with self-rated health and functional ability than with the number of disease or prescribed medicaments. The more frequent, longevity-related homozygote (GG) in rs16847897 was associated with all three aspects of self-assessments-health, mobility, and independence-indicating that this TERC locus might have a true impact on the overall vitality of the oldest-old persons.

RNF126, 168 and CUL1: The Potential Utilization of Multi-Functional E3 Ubiquitin Ligases in Genome Maintenance for Cancer Therapy

Ubiquitination is a post-translational modification (PTM) that is involved in proteolysis, protein-protein interaction, and signal transduction. Accumulation of mutations and genomic instability are characteristic of cancer cells, and dysfunction of the ubiquitin pathway can contribute to abnormal cell physiology. Because mutations can be critical for cells, DNA damage repair, cell cycle regulation, and apoptosis are pathways that are in close communication to maintain genomic integrity. Uncontrolled cell proliferation due to abnormal processes is a hallmark of cancer, and mutations, changes in expression levels, and other alterations of ubiquitination factors are often involved. Here, three E3 ubiquitin ligases will be reviewed in detail. RNF126, RNF168 and CUL1 are involved in DNA damage response (DDR), DNA double-strand break (DSB) repair, cell cycle regulation, and ultimately, cancer cell proliferation control. Their involvement in multiple cellular pathways makes them an attractive candidate for cancer-targeting therapy. Functional studies of these E3 ligases have increased over the years, and their significance in cancer is well reported. There are continuous efforts to develop drugs targeting the ubiquitin pathway for anticancer therapy, which opens up the possibility for these E3 ligases to be evaluated for their potential as a target protein for anticancer therapy.

X-ray cross-complementing family: the bridge linking DNA damage repair and cancer

Genomic instability is a common hallmark of human tumours. As a carrier of genetic information, DNA is constantly threatened by various damaging factors that, if not repaired in time, can affect the transmission of genetic information and lead to cellular carcinogenesis. In response to these threats, cells have evolved a range of DNA damage response mechanisms, including DNA damage repair, to maintain genomic stability. The X-ray repair cross-complementary gene family (XRCC) comprises an important class of DNA damage repair genes that encode proteins that play important roles in DNA single-strand breakage and DNA base damage repair. The dysfunction of the XRCC gene family is associated with the development of various tumours. In the context of tumours, mutations in XRCC and its aberrant expression, result in abnormal DNA damage repair, thus contributing to the malignant progression of tumour cells. In this review, we summarise the significant roles played by XRCC in diverse tumour types. In addition, we discuss the correlation between the XRCC family members and tumour therapeutic sensitivity.

PARP1 modulates METTL3 promoter chromatin accessibility and associated LPAR5 RNA m6A methylation to control cancer cell radiosensitivity

Chromatin remodeling and N6-methyladenosine (m6A) modification are two critical layers in controlling gene expression and DNA damage signaling in most eukaryotic bioprocesses. Here, we report that poly(ADP-ribose) polymerase 1 (PARP1) controls the chromatin accessibility of METTL3 to regulate its transcription and subsequent m6A methylation of poly(A)+ RNA in response to DNA damage induced by radiation. The transcription factors nuclear factor I-C (NFIC) and TATA binding protein (TBP) are dependent on PARP1 to access the METTL3 promoter to activate METTL3 transcription. Upon irradiation or PARP1 inhibitor treatment, PARP1 disassociated from METTL3 promoter chromatin, which resulted in attenuated accessibility of NFIC and TBP and, consequently, suppressed METTL3 expression and RNA m6A methylation. Lysophosphatidic Acid Receptor 5 (LPAR5) mRNA was identified as a target of METTL3, and m6A methylation was located at A1881. The level of m6A methylation of LPAR5 significantly decreased, along with METTL3 depression, in cells after irradiation or PARP1 inhibition. Mutation of the LPAR5 A1881 locus in its 3' UTR results in loss of m6A methylation and, consequently, decreased stability of LPAR5 mRNA. METTL3-targeted small-molecule inhibitors depress murine xenograft tumor growth and exhibit a synergistic effect with radiotherapy in vivo. These findings advance our comprehensive understanding of PARP-related biological roles, which may have implications for developing valuable therapeutic strategies for PARP1 inhibitors in oncology.

Identification of m5C-related lncRNAs signature to predict prognosis and therapeutic responses in esophageal squamous cell carcinoma patients

Esophageal squamous cell carcinoma (ESCC) has a dismal prognosis because of atypical early symptoms and heterogeneous therapeutic responses. 5-methylcytosine (m5C) modification plays an important role in the onset and development of many tumors and is widespread in long non-coding RNA (lncRNA) transcripts. However, the functions of m5C and lncRNAs in ESCC have not been completely elucidated. Herein, this study aimed to explore the role of m5C-related lncRNAs in ESCC. The RNA-seq transcriptome profiles and clinical information were downloaded from the TCGA-ESCC database. Pearson analysis was used to identify m5C-related lncRNAs. Then we established the m5C-related lncRNAs prognostic signature (m5C-LPS) using univariate Cox and least absolute shrinkage and selection operator (LASSO) regression analysis. Then, the prognostic value of m5C-LPS was evaluated internally and externally using the TCGA-ESCC and GSE53622 databases through multiple methods. We also detected the expression of these lncRNAs in ESCC cell lines and patient tissues. Fluorescence in situ hybridization (FISH) was used to detect the prognostic value of specific lncRNA. In addition, clinical parameters, immune status, genomic variants, oncogenic pathways, enrichment pathways, and therapeutic response features associated with m5C-LPS were explored using bioinformatics methods. We constructed and validated a prognostic signature based on 9 m5C-related lncRNAs (AC002091.2, AC009275.1, CAHM, LINC02057.1, AC0006329.1, AC037459.3, AC064807.1, ATP2B1-AS1, and UBAC2-AS1). The quantitative real-time polymerase chain reaction (qRT-PCR) revealed that most lncRNAs were upregulated in ESCC cell lines and patient tissues. And AC002091.2 was validated to have significant prognostic value in ESCC patients. A composite nomogram was generated to facilitate clinical practice by integrating this signature with the N stage. Besides, patients in the low-risk group were characterized by good clinical outcomes, favorable immune status, and low oncogenic alteration. Function enrichment analysis indicated that the risk score was associated with mRNA splicing, ncRNA processing, and DNA damage repair response. At the same time, we found significant differences in the responses to chemoradiotherapy between the two groups, proving the value of m5C-LPS in treatment decision-making in ESCC. This study established a novel prognostic signature based on 9 m5C-related lncRNAs, which is a promising biomarker for predicting clinical outcomes and therapeutic response in ESCC.

Pure Organic AIE Nanoscintillator for X-ray Mediated Type I and Type II Photodynamic Therapy

X-ray induced photodynamic therapy (X-PDT) circumvents the poor penetration depth of conventional PDT with minimal radio-resistance generation. However, conventional X-PDT typically requires inorganic scintillators as energy transducers to excite neighboring photosensitizers (PSs) to generate reactive oxygen species (ROS). Herein, a pure organic aggregation-induced emission (AIE) nanoscintillator (TBDCR NPs) that can massively generate both type I and type II ROS under direct X-ray irradiation is reported for hypoxia-tolerant X-PDT. Heteroatoms are introduced to enhance X-ray harvesting and ROS generation ability, and AIE-active TBDCR exhibits aggregation-enhanced ROS especially less oxygen-dependent hydroxyl radical (HO•- , type I) generation ability. TBDCR NPs with a distinctive PEG crystalline shell to provide a rigid intraparticle microenvironment show further enhanced ROS generation. Intriguingly, TBDCR NPs show bright near-infrared fluorescence and massive singlet oxygen and HO•- generation under direct X-ray irradiation, which demonstrate excellent antitumor X-PDT performance both in vitro and in vivo. To the best of knowledge, this is the first pure organic PS capable of generating both 1 O2 and radicals (HO•- ) in response to direct X-ray irradiation, which shall provide new insights for designing organic scintillators with excellent X-ray harvesting and predominant free radical generation for efficient X-PDT.

Effectiveness of radiotherapy and targeted radionuclide therapy for melanoma in preclinical mouse models: A combination treatments overview

Cutaneous melanoma is an aggressive and highly metastatic skin cancer. In recent years, immunotherapy and targeted small-molecule inhibitors have improved the overall survival of patients. Unfortunately, most patients in advanced stages of disease exhibit either intrinsically resistant or rapidly acquire resistance to these approved treatments. However, combination treatments have emerged to overcome resistance, and novel treatments based on radiotherapy (RT) and targeted radionuclide therapy (TRT) have been developed to treat melanoma in the preclinical mouse model, raising the question of whether synergy in combination therapies may motivate and increase their use as primary treatments for melanoma. To help clarify this question, we reviewed the studies in preclinical mouse models where they evaluated RT and TRT in combination with other approved and unapproved therapies from 2016 onwards, focusing on the type of melanoma model used (primary tumor and or metastatic model). PubMed® was the database in which the search was performed using mesh search algorithms resulting in 41 studies that comply with the inclusion rules of screening. Studies reviewed showed that synergy with RT or TRT had strong antitumor effects, such as tumor growth inhibition and fewer metastases, also exhibiting systemic protection. In addition, most studies were carried out on antitumor response for the implanted primary tumor, demonstrating that more studies are needed to evaluate these combined treatments in metastatic models on long-term protocols.

Multifaceted Roles of Copper Ions in Anticancer Nanomedicine

The significantly increased copper level in tumor tissues and serum indicates the close association of copper ions with tumor development, making copper ions attractive targets in the development of novel tumor treatment methods. The advanced nanotechnology developed in the past decades provides great potential for tumor therapy, among which Cu-based nanotherapeutic systems have received greater attention. Herein, the multifaceted roles of copper ions in cancer progression are summarized and the recent advances in the copper-based nanostructures or nanomedicines for different kinds of tumor therapies including copper depletion therapy, copper-based cytotoxins, copper-ion-based chemodynamic therapy and its combination with other treatments, and copper-ion-induced ferroptosis and cuproptosis activation are discussed. Furthermore, the perspectives for the further development of copper-ion-based nanomedicines for tumor therapy and clinic translation are presented by the authors.

ATM inhibition augments type I interferon response and antitumor T-cell immunity when combined with radiation therapy in murine tumor models

BACKGROUND

Radiation therapy (RT) elicits DNA double-strand breaks, resulting in tumor cytotoxicity and a type I interferon (IFN) response via stimulator of interferon genes (STING) activation. We investigated whether combining RT with an ataxia-telangiectasia mutated inhibitor promoted these effects and amplified tumor immunity.

METHODS

Mice-bearing syngeneic flank tumors (MOC2 head and neck squamous cell carcinoma or B78 melanoma) were treated with tumor-directed RT and oral administration of AZD0156. Specific immune cell depletion, type 1 interferon receptor 1 knock-out mice (IFNAR1-KO), and STING-deficient tumor cells were used to investigate tumor-immune crosstalk following RT and AZD0156 treatment.

RESULTS

Combining RT and AZD0156 reduced tumor growth compared with RT or AZD0156 alone in mice bearing MOC2 or B78 tumors. Low-dose AZD0156 (1-100 nM) alone did not affect tumor cell proliferation but suppressed tumor cell clonogenicity in combination with RT. Low-dose AZD0156 with RT synergistically increased IFN-β, major histocompatibility complex (MHC)-I, and programmed death-ligand 1 (PD-L1) expression in tumor cells. In contrast to wild-type mice, IFNAR1-KO mice showed reduced CD8+T cell tumor infiltration and poor survival following RT+AZD0156 treatment. CD8+T cell depletion reduced antitumor response during RT+AZD0156 treatment. STING-deficient MOC2 (MOC2-STING+/-) or B78 (B78-STING-/-) tumors eliminated the effects of RT+AZD0156 on the expression of IFN-β, MHC-I, and PD-L1, and reduced CD8+T cell infiltration and migration. Additional anti-PD-L1 therapy promoted antitumor response by elevation of tumor-MHC-I and lymphocyte activation.

CONCLUSIONS

Combined radiation and AZD0156 increase STING-dependent antitumor response. Tumor-derived cell-autonomous IFN-β amplification drives both MHC-I and PD-L1 induction at the tumor cell surface, which is required by anti-PD-L1 therapy to promote antitumor immune response following RT and AZD0156 combination therapy.

The Current Trend of Radiation Therapy for Patients with Localized Prostate Cancer

A recent approach to radiotherapy for prostate cancer is the administration of high doses of radiation to the prostate while minimizing the risk of side effects. Thus, image-guided radiotherapy utilizes advanced imaging techniques and is a feasible strategy for increasing the radiation dose. New radioactive particles are another approach to achieving high doses and safe procedures. Prostate brachytherapy is currently considered as a combination therapy. Spacers are useful to protect adjacent organs, specifically the rectum, from excessive radiation exposure.

Review of possible mechanisms of radiotherapy resistance in cervical cancer

Radiotherapy is one of the main treatments for cervical cancer. Early cervical cancer is usually considered postoperative radiotherapy alone. Radiotherapy combined with cisplatin is the standard treatment for locally advanced cervical cancer (LACC), but sometimes the disease will relapse within a short time after the end of treatment. Tumor recurrence is usually related to the inherent radiation resistance of the tumor, mainly involving cell proliferation, apoptosis, DNA repair, tumor microenvironment, tumor metabolism, and stem cells. In the past few decades, the mechanism of radiotherapy resistance of cervical cancer has been extensively studied, but due to its complex process, the specific mechanism of radiotherapy resistance of cervical cancer is still not fully understood. In this review, we discuss the current status of radiotherapy resistance in cervical cancer and the possible mechanisms of radiotherapy resistance, and provide favorable therapeutic targets for improving radiotherapy sensitivity. In conclusion, this article describes the importance of understanding the pathway and target of radioresistance for cervical cancer to promote the development of effective radiotherapy sensitizers.

Parp Inhibitors and Radiotherapy: A New Combination for Prostate Cancer (Systematic Review)

PARPi, in combination with ionizing radiation, has demonstrated the ability to enhance cellular radiosensitivity in different tumors. The rationale is that the exposure to radiation leads to both physical and biochemical damage to DNA, prompting cells to initiate three primary mechanisms for DNA repair. Two double-stranded DNA breaks (DSB) repair pathways: (1) non-homologous end-joining (NHEJ) and (2) homologous recombination (HR); and (3) a single-stranded DNA break (SSB) repair pathway (base excision repair, BER). In this scenario, PARPi can serve as radiosensitizers by leveraging the BER pathway. This mechanism heightens the likelihood of replication forks collapsing, consequently leading to the formation of persistent DSBs. Together, the combination of PARPi and radiotherapy is a potent oncological strategy. This combination has proven its efficacy in different tumors. However, in prostate cancer, there are only preclinical studies to support it and, recently, an ongoing clinical trial. The objective of this paper is to perform a review of the current evidence regarding the use of PARPi and radiotherapy (RT) in PCa and to give future insight on this topic.

Endothelial Cell Response to Combined Photon or Proton Irradiation with Doxorubicin

Surgery, radiotherapy, and chemotherapy are essential treatment modalities to target cancer cells, but they frequently cause damage to the normal tissue, potentially leading to side effects. As proton beam radiotherapy (PBT) can precisely spare normal tissue, this therapeutic option is of increasing importance regarding (neo-)adjuvant and definitive anti-cancer therapies. Akin to photon-based radiotherapy, PBT is often combined with systemic treatment, such as doxorubicin (Dox). This study compares the cellular response of human microvascular endothelial cells (HMEC-1) following irradiation with photons (X) or protons (H) alone and also in combination with different sequences of Dox. The cellular survival, cell cycle, apoptosis, proliferation, viability, morphology, and migration were all investigated. Dox monotreatment had minor effects on all endpoints. Both radiation qualities alone and in combination with longer Dox schedules significantly reduced clonogenic survival and proliferation, increased the apoptotic cell fraction, induced a longer G2/M cell cycle arrest, and altered the cell morphology towards endothelial-to-mesenchymal-transition (EndoMT) processes. Radiation quality effects were seen for metabolic viability, proliferation, and motility of HMEC-1 cells. Additive effects were found for longer Dox schedules. Overall, similar effects were found for H/H-Dox and X/X-Dox. Significant alterations between the radiation qualities indicate different but not worse endothelial cell damage by H/H-Dox.

The mechanistic role of cardiac glycosides in DNA damage response and repair signaling

Cardiac glycosides (CGs) are a class of bioactive organic compounds well-known for their application in treating heart disease despite a narrow therapeutic window. Considerable evidence has demonstrated the potential to repurpose CGs for cancer treatment. Chemical modification of these CGs has been utilized in attempts to increase their anti-cancer properties; however, this has met limited success as their mechanism of action is still speculative. Recent studies have identified the DNA damage response (DDR) pathway as a target of CGs. DDR serves to coordinate numerous cellular pathways to initiate cell cycle arrest, promote DNA repair, regulate replication fork firing and protection, or induce apoptosis to avoid the survival of cells with DNA damage or cells carrying mutations. Understanding the modus operandi of cardiac glycosides will provide critical information to better address improvements in potency, reduced toxicity, and the potential to overcome drug resistance. This review summarizes recent scientific findings of the molecular mechanisms of cardiac glycosides affecting the DDR signaling pathway in cancer therapeutics from 2010 to 2022. We focus on the structural and functional differences of CGs toward identifying the critical features for DDR targeting of these agents.

YWHAZ and TBP are potential reference gene candidates for qPCR analysis of response to radiation therapy in colorectal cancer

The expression profiles of conventional reference genes (RGs), including ACTB and GAPDH, used in quantitative real-time PCR (qPCR), vary depending on tissue types and environmental conditions. We searched for suitable RGs for qPCR to determine the response to radiotherapy in colorectal cancer (CRC) cell lines, organoids, and patient-derived tissues. Ten CRC cell lines (Caco-2, COLO 205, DLD-1, HCT116, HCT-15, HT-29, RKO, SW1116, SW480, and SW620) and organoids were selected and irradiated with 2, 10 or 21 grays (Gy) based on the previous related studies conducted over the last decade. The expression stability of 14 housekeeping genes (HKGs; ACTB, B2M, G6PD, GAPDH, GUSB, HMBS, HPRT1, IPO8, PGK1, PPIA, TBP, TFRC, UBC, and YWHAZ) after irradiation was evaluated using RefFinder using raw quantification cycle (Cq) values obtained from samples before and after irradiation. The expression stability of HKGs were also evaluated for paired fresh frozen tissues or formalin-fixed, paraffin-embedded samples obtained from CRC patients before and after chemoradiotherapy. The expression of YWHAZ and TBP encoding 14-3-3-zeta protein and TATA-binding protein were more stable than the other 12 HKGs in CRC cell lines, organoids, and patient-derived tissues after irradiation. The findings suggest that YWHAZ and TBP are potential RG candidates for normalizing qPCR results in CRC radiotherapy experiments.

Roles of lysophosphatidic acid (LPA) receptor-2 (LPA2) in the regulation of cellular responses induced by X-ray irradiation and hydrogen peroxide in pancreatic cancer cells

PURPOSE

Lysophosphatidic acid (LPA) receptor-mediated signaling regulates various biological functions in cancer cells. This study aimed to evaluate the roles of LPA receptor-2 (LPA2) in cellular responses induced by X-ray irradiation in pancreatic cancer PANC-1 cells. Since X-ray irradiation generates reactive oxygen species (ROS), PANC-1 cells were treated with hydrogen peroxide (H2O2). H2O2 is a key member of ROS.

METHODS

To investigate the cell survival rate to X-ray irradiation, PANC-1 cells were irradiated with X-rays (2.5-15 Gy). LPAR2 expression levels were measured by quantitative real-time RT-PCR analysis. The effects of LPA2 on the cell survival and motility were evaluated using LPA2 knockdown cells. To establish H2O2 treated cells, PANC-1 cells were cultured in 10% FBS-DMEM with H2O2 (30 µM) for 2 weeks. The cell motility and survival rate to cisplatin (CDDP) of H2O2 treated cells were examined.

RESULTS

LPAR2 expression was significantly increased in PANC-1 cells irradiated with X-rays. PANC-1 cell motility was markedly decreased by X-ray irradiation. The reduced cell motility activity by X-ray irradiation was enhanced by LPA2 knockdown. The cell survival to X-ray irradiation was elevated in PANC-1 cells treated with GRI-977143 (LPA2 agonist) and suppressed by LPA2 knockdown. On the other hand, LPAR2 expression was markedly higher in H2O2 treated cells than in H2O2 untreated cells. H2O2 treated cells showed the high cell survival to CDDP in comparison with H2O2 untreated cells. GRI-977143 increased the cell survival to CDDP of H2O2 treated cells, while LPA2 knockdown suppressed.

CONCLUSIONS

The present results suggest that the activation of LPA2-mediated signaling plays an important role in the modulation of cellular functions induced by X-ray irradiation and H2O2 in PANC-1 cells.

Candidate biomarkers and persistent transcriptional responses after low and high dose ionizing radiation at high dose rate

PURPOSE

Development of an integrated time and dose model to explore the dynamics of gene expression alterations and identify biomarkers for biodosimetry following low- and high-dose irradiations at high dose rate.

MATERIAL AND METHODS

We utilized multiple transcriptome datasets (GSE8917, GSE43151, and GSE23515) from Gene Expression Omnibus (GEO) for identifying candidate biological dosimeters. A linear mixed-effects model with random intercept was used to explore the dose-time dynamics of transcriptional responses and to functionally characterize the time- and dose-dependent changes in gene expression.

RESULTS

We identified genes that are correlated with dose and time and discovered two clusters of genes that are either positively or negatively correlated with both dose and time based on the parameters of the model. Genes in these two clusters may have persistent transcriptional alterations. Twelve potential transcriptional markers for dosimetry-ARHGEF3, BAX, BBC3, CCDC109B, DCP1B, DDB2, F11R, GADD45A, GSS, PLK3, TNFRSF10B, and XPC were identified. Of these genes, BAX, GSS, and TNFRSF10B are positively associated with both dose and time course, have a persistent transcriptional response, and might be better biological dosimeters.

CONCLUSIONS

With the proposed approach, we may identify candidate biomarkers that change monotonically in relation to dose, have a persistent transcriptional response, and are reliable over a wide dose range.

Antioxidant Nanoparticles Restore Cisplatin-Induced Male Fertility Defects by Promoting MDC1-53bp1-Associated Non-Homologous DNA Repair Mechanism and Sperm Intracellular Calcium Influx

Introduction

Cisplatin, a commonly used anticancer compound, exhibits severe off-target organ toxicity. Due to its wide application in cancer treatment, the reduction of its damage to normal tissue is an imminent clinical need. Cisplatin-induced testicular oxidative stress and damage lead to male sub- or infertility. Despite earlier studies showing that the natural polyphenol extracts honokiol serve as the free radical scavenger that reduces the accumulation of intracellular free radicals, whether honokiol exhibits direct effects on the testis and sperm is unclear. Thus, the aim of the current study is to investigate the direct effects of honokiol on testicular recovery and sperm physiology.

Methods

We encapsulated this polyphenol antioxidation compound into liposome-based nanoparticles (nHNK) and gave intraperitoneally to mice at a dosage of 5 mg/kg body mass every other day for consecutive 6 weeks.

Results

We showed that nHNK promotes MDC1-53bp1-associated non-homologous DNA double-strand break repair signaling pathway that minimizes cisplatin-induced DNA damage. This positive effect restores spermatogenesis and allows the restructuring of the multi-spermatogenic layers in the testis. By reducing mitochondrial oxidative damage, nHNK also protects sperm mitochondrial structure and maintains both testicular and sperm ATP production. By a yet-to-identify mechanism, nHNK restores sperm calcium influx at the sperm midpiece and tail, which is essential for sperm hypermotility and their interaction with the oocyte.

Discussion

Taken together, the nanoparticulated antioxidant counteracts cisplatin-induced male fertility defects and benefits patients undertaking cisplatin-based chemotherapy. These data may allow the reintroduction of cisplatin for systemic applications in patients at clinics with reduced testicular toxicity.

Preclinical evaluation of Mito-LND, a targeting mitochondrial metabolism inhibitor, for glioblastoma treatment

BACKGROUND

Glioblastoma (GBM) is a brain tumor with the highest level of malignancy and the worst prognosis in the central nervous system. Mitochondrial metabolism plays a vital role in the occurrence and development of cancer, which provides critical substances to support tumor anabolism. Mito-LND is a novel small-molecule inhibitor that can selectively inhibit the energy metabolism of tumor cells. However, the therapeutic effect of Mito-LND on GBM remains unclear.

METHODS

The present study evaluated the inhibitory effect of Mito-LND on the growth of GBM cells and elucidated its potential mechanism.

RESULTS

The results showed that Mito-LND could inhibit the survival, proliferation and colony formation of GBM cells. Moreover, Mito-LND induced cell cycle arrest and apoptosis. Mechanistically, Mito-LND inhibited the activity of mitochondrial respiratory chain complex I and reduced mitochondrial membrane potential, thus promoting ROS generation. Importantly, Mito-LND could inhibit the malignant proliferation of GBM by blocking the Raf/MEK/ERK signaling pathway. In vivo experiments showed that Mito-LND inhibited the growth of GBM xenografts in mice and significantly prolonged the survival time of tumor-bearing mice.

CONCLUSION

Taken together, the current findings support that targeting mitochondrial metabolism may be as a potential and promising strategy for GBM therapy, which will lay the theoretical foundation for further clinical trials on Mito-LND in the future.

Innate Immune System in the Context of Radiation Therapy for Cancer

Radiation therapy (RT) remains an integral component of modern oncology care, with most cancer patients receiving radiation as a part of their treatment plan. The main goal of ionizing RT is to control the local tumor burden by inducing DNA damage and apoptosis within the tumor cells. The advancement in RT, including intensity-modulated RT (IMRT), stereotactic body RT (SBRT), image-guided RT, and proton therapy, have increased the efficacy of RT, equipping clinicians with techniques to ensure precise and safe administration of radiation doses to tumor cells. In this review, we present the technological advancement in various types of RT methods and highlight their clinical utility and associated limitations. This review provides insights into how RT modulates innate immune signaling and the key players involved in modulating innate immune responses, which have not been well documented earlier. Apoptosis of cancer cells following RT triggers immune systems that contribute to the eradication of tumors through innate and adoptive immunity. The innate immune system consists of various cell types, including macrophages, dendritic cells, and natural killer cells, which serve as key mediators of innate immunity in response to RT. This review will concentrate on the significance of the innate myeloid and lymphoid lineages in anti-tumorigenic processes triggered by RT. Furthermore, we will explore essential strategies to enhance RT efficacy. This review can serve as a platform for researchers to comprehend the clinical application and limitations of various RT methods and provides insights into how RT modulates innate immune signaling.

P53-response circRNA_0006420 aggravates lung cancer radiotherapy resistance by promoting formation of HUR/PTBP1 complex

BACKGROUND

p53 wild-type lung cancer cells can develop radiation resistance. Circular RNA (circRNA) consists of a family of transcripts with exclusive structures. circRNA is critical in tumorigenesis and is a potential biomarker or therapeutic target. It is uncertain how circRNA expression and functions are regulated post-radiation in p53 wild-type cancer cells.

METHODS

A549 or H1299 cells were divided into p53-wt and p53-KO groups by CRISPR/Cas9; both groups were subjected to 4Gy ionizing radiation (IR: p53-wt-IR and p53-KO-IR). RNA-seq, CCK8, cell cycle, and other functional and mechanism experiments were performed in vivo. p53 gene knockout mice were generated to test the cell results in vitro.

RESULTS

circRNAs were found in differential groups. circRNA_0006420 (IRSense) was upregulated in p53-wt cells but had the same expression level as p53-KO cells after radiation, indicating that p53 silencing prevents its upregulation after IR. In the presence of p53, upregulated IRSense post-radiation induces G2/M arrest by regulating DNA damage repair (DDR) pathway-related proteins. Meanwhile, upregulated IRSense post-radiation aggravates the radiation-induced epithelial-mesenchymal transition (EMT). Interestingly, in the presence of p53, it promotes IRSense/HUR/PTBP1 complex formation resulting in the promotion of the radiation-induced EMT. Moreover, c-Jun regulates the upregulation of p53 transcription after radiation treatment. For these lung cancer cells with p53, upregulated IRSense aggravates lung cancer cell proliferation and increases radiation resistance by interacting with HUR (ElAV-like protein 1) and PTBP1 (polypyrimidine tract-binding protein 1) in the nucleus.

CONCLUSIONS

Lung cancer cells retaining p53 may upregulate circRNA_0006420 (IRSense) expression post radiation to form an IRSense/HUR/PTBP1 complex leading to radiotherapy resistance. This study furthers our understanding of the roles of circRNA in regulating the effect of radiotherapy and provides novel therapeutic avenues for effective clinical lung cancer therapies.

Pharmacological inhibition of BAP1 recruits HERC2 to competitively dissociate BRCA1-BARD1, suppresses DNA repair and sensitizes CRC to radiotherapy

Radiotherapy is widely used in the management of advanced colorectal cancer (CRC). However, the clinical efficacy is limited by the safe irradiated dose. Sensitizing tumor cells to radiotherapy via interrupting DNA repair is a promising approach to conquering the limitation. The BRCA1-BARD1 complex has been demonstrated to play a critical role in homologous recombination (HR) DSB repair, and its functions may be affected by HERC2 or BAP1. Accumulated evidence illustrates that the ubiquitination-deubiquitination balance is involved in these processes; however, the precise mechanism for the cross-talk among these proteins in HR repair following radiation hasn't been defined. Through activity-based profiling, we identified PT33 as an active entity for HR repair suppression. Subsequently, we revealed that BAP1 serves as a novel molecular target of PT33 via a CRISPR-based deubiquitinase screen. Mechanistically, pharmacological covalent inhibition of BAP1 with PT33 recruits HERC2 to compete with BARD1 for BRCA1 interaction, interrupting HR repair. Consequently, PT33 treatment can substantially enhance the sensitivity of CRC cells to radiotherapy in vitro and in vivo. Overall, these findings provide a mechanistic basis for PT33-induced HR suppression and may guide an effective strategy to improve therapeutic gain.

Ionizing radiation triggers mitophagy to enhance DNA damage in cancer cells

Radiotherapy is an important cancer treatment strategy that causes DNA damage in tumor cells either directly or indirectly. Autophagy is a physiological process linked to DNA damage. Mitophagy is a form of autophagy, which specifically targets and eliminates impaired mitochondria, thereby upholding cellular homeostasis. However, the connection between DNA damage and mitophagy has yet to be fully elucidated. We found that mitophagy, as an upstream signal, increases ionizing radiation-induced DNA damage by downregulating or overexpressing key mitophagy proteins Parkin and BNIP3. Enhancing the basal level of mitophagy in conjunction with X-ray irradiation can potentially diminish cell cycle arrest at the G2/M phase, substantially elevate the accumulation of γ-H2AX, 53BP1, and PARP1 foci within the nucleus, augment DNA damage, and facilitate the demise of tumor cells. Consequently, this approach prolongs the survival of melanoma-bearing mice. The findings of this study are anticipated to offer a therapeutic approach for enhancing the therapeutic effectiveness of radiotherapy.

ΔNp63 Regulates Radioresistance in Human Head and Neck Squamous Carcinoma Cells

Radiation therapy is commonly used to treat head and neck squamous cell carcinoma (HNSCC); however, recurrence results from the development of radioresistant cancer cells. Therefore, it is necessary to identify the underlying mechanisms of radioresistance in HNSCC. Previously, we showed that the inhibition of karyopherin-β1 (KPNB1), a factor in the nuclear transport system, enhances radiation-induced cytotoxicity, specifically in HNSCC cells, and decreases the localization of SCC-specific transcription factor ΔNp63. This suggests that ΔNp63 may be a KPNB1-carrying nucleoprotein that regulates radioresistance in HNSCC. Here, we determined whether ΔNp63 is involved in the radioresistance of HNSCC cells. Cell survival was measured by a colony formation assay. Apoptosis was assessed by annexin V staining and cleaved caspase-3 expression. The results indicate that ΔNp63 knockdown decreased the survival of irradiated HNSCC cells, increased radiation-induced annexin V+ cells, and cleaved caspase-3 expression. These results show that ΔNp63 is involved in the radioresistance of HNSCC cells. We further investigated which specific karyopherin-α (KPNA) molecules, partners of KPNB1 for nuclear transport, are involved in nuclear ΔNp63 expression. The analysis of nuclear ΔNp63 protein expression suggests that KPNA1 is involved in nuclear ΔNp63 expression. Taken together, our results suggest that ΔNp63 is a KPNB1-carrying nucleoprotein that regulates radioresistance in HNSCC.