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

Design and synthesis of phenanthridinone and phenanthridine derivatives and their radiosensitizing activity

To find novel radiosensitizers, a series of phenanthridinone and phenanthridine derivatives were designed and synthesized based on the structural simplification strategy from the natural product oxynitidine scaffold. Colony formation assays indicated that the phenanthridine derivative B9 showed strong radiosensitizing activity in colorectal cancer HCT116 cells in a concentration- and dose-dependent manner. Further investigations revealed that B9 could increase intracellular ionizing radiation-induced ROS levels and DNA damage, and induce cancer cell apoptosis and cycle arrest at G2/M phase. These results suggest that phenanthridine chemotype is a novel scaffold for the discovery of radiosensitizers.

A self-gelling hemostatic powder boosting radiotherapy-elicited NK cell immunity to combat postoperative hepatocellular carcinoma relapse

Liver resection represents a main curative treatment for patients with early-stage hepatocellular carcinoma (HCC), but there is a rather high incidence of postoperative HCC relapse, which severely shortens long-term survival time. Currently, no standard adjuvant strategies are available for preventing HCC relapse in clinical practice. Impaired natural killer (NK) cell anti-tumor immunity has been disclosed as a crucial root of HCC relapse, indicating that reinstating NK cell anti-tumor immunity may show promise to curb HCC relapse. Coincidently, mounting evidence shows that radiotherapy (RT) can trigger NK cell anti-tumor immunity, though its mechanisms have never been completely elucidated. Herein, we uncover that RT can induce immunogenic cell death and activate cGAS-STING pathway in HCC cells to elicit NK cell anti-tumor immunity. However, RT is also revealed to enhance autophagy and CD73 expression in HCC cells, as well as neutrophil extracellular traps (NETs) formation, which largely limits RT-induced activation of NK cell anti-tumor immunity. Therefore, a cocktail of autophagy inhibitor 3-methyladenine, CD73 inhibitor ARL 67156 trisodium and NETs lyase DNase I may sensitize RT to reinvigorate NK cell anti-tumor immunity and thus prevent HCC relapse postresection. To minimize therapy-related side effects, a nanocomposite powder encapsulating such a triple-drug cocktail is developed. This powder can rapidly form adhesive hydrogel in situ after applied to surgical margin, consequently fulfilling liver-localized sustained drug delivery. Importantly, it can sensitize RT to reinstate NK cell anti-tumor immunity to combat postoperative HCC relapse in Heap1-6-HCC murine model. Besides, this powder can also generate rapid hemostasis in rat and porcine models. Altogether, this work provides an innovative strategy to thwart postoperative HCC relapse and bleeding.

LZTS3 represses tumorigenesis and radioresistance via CK1δ and β-TrCP-mediated ubiquitination pathway in lung cancer

Radioresistance is one of the main causes for local treatment failure in lung cancer. Nevertheless, the potential mechanisms of radioresistance in lung cancer have not been elucidated completely. Here, we discover a carcinoma-inhibiting protein called leucine zipper tumor suppressor 3 (LZTS3), which is low-expressed and related to adverse outcome in lung cancer. Moreover, our studies demonstrate that LZTS3 restrains cell proliferation and radioresistance in vitro and in vivo. Mechanistically, protein kinase CK1δ interacts with LZTS3, resulting in E3 ubiquitin ligase β-TrCP recognizes and binds to LZTS3. Thus, LZTS3 is degraded by the ubiquitin-proteasome pathway. We also identify two conserved degrons (DSGRNS and DSGRAS) are essential for the ubiquitinated degradation of LZTS3 by CK1δ and β-TrCP. More importantly, we detect that the CK1δ and β-TrCP-mediated degradation of LZTS3 facilitate the cell growth, proliferation and radioresistance in lung cancer. Collectivelly, our results suggest that LZTS3 regulates tumorigenesis and radioresistance in lung cancer depend on a CK1δ and β-TrCP-mediated ubiquitin-proteasome pathway. LZTS3 may be a new molecular target for lung cancer treatment.

Guiqi Baizhu decoction enhances radiosensitivity in non-small cell lung cancer by inhibiting the HIF-1α/DNA-PKcs axis-mediated DNA repair

BACKGROUND

Radiotherapy is one of the main treatments for non-small cell lung cancer (NSCLC), and radiosensitivity is a determinant of its efficacy. Therefore, enhancing the radiosensitivity is of great significance to improve the clinical efficacy of non-small cell lung cancer (NSCLC).

PURPOSE

This study intended to investigate the radiosensitisation effect and mechanism of Guiqi Baizhu decoction (GQBZD) on non-small cell lung cancer (NSCLC) and the role of hypoxia-inducible factor-1 alpha (HIF-1α)/DNA-dependent protein kinase catalytic subunit (DNA-PKcs) axis-mediated DNA non-homologous end joining (NHEJ) repair in NSCLC radiotherapy.

STUDY DESIGN

In vivo experimental model was Lewis subcutaneous transplantation tumor model of in C57 black 6 (C57BL/6) mice, and in vitro experimental models were A549, H1299 and H460 cells.

METHODS

In vivo experimental model was Lewis subcutaneous transplantation tumor model of in C57 black 6 (C57BL/6) mice. After the model was successfully established, the tumor was irradiated locally with 4 Gy X-ray, and 10.465 g/kg Guiqi Baizhu Decoction (GQBZD) was administered by gavage on the second day after irradiation for a total of 10 days. The morphological changes in tumour tissues were observed by HE staining, Ki67 levels in tumour tissues were detected by immunohistochemistry, the apoptosis in tumour cells were detected by Tunel staining. In vitro experimental models were different NSCLC cells (A549, H1299 and H460), irradiated by 2 Gy X-rays and then intervened with 5%, 10% and 20% Guiqi Baizhu Decoction (GQBZD)-containing serum for 24 h. A549 stably-transformed cell lines knocking down and overexpressing HIF-1α were also constructed by lentiviral transfection. The cell proliferation was detected by CCK-8 and clone formation, the apoptosis and cell cycle was detected by flow cytometry. Network pharmacology and transcriptomics to investigate key targets and pathways of GQBZD effects on NSCLC irradiation, further validated by immunofluorescence and Western blot.

RESULTS

In vivo experiments confirmed that GQBZD combined with irradiation could inhibit the growth of Lewis subcutaneous transplantation tumor, reduce the expression of Ki67 and promote the apoptosis of tumour cells. In vitro experiments confirmed that GQBZD combined with irradiation inhibited the proliferation of different NSCLC cells, promoted NSCLC cell apoptosis and G2/M-phase arrest, and induced the expression of phosphorylated histone H2AX (γ-H2AX) in NSCLC cells, which showed a good radiosensitisation effect. Mechanistically, GQBZD exerts its radiosensitisation effect on NSCLC mainly through the HIF-1α signalling pathway. Meanwhile, under irradiation conditions, the expression of HIF-1α and DNA-PKcs were positively correlated, and HIF-1α had a regulatory effect on DNA-PKcs, promoting DNA-PKcs-dependent non-homologous end joining (NHEJ) repair. In addition, GQBZD combined irradiation down-regulated the expression of HIF-1α, DNA-PKcs, and NHEJ repair-related proteins in NSCLC cells, while reversing the expression of HIF-1α, DNA-PKcs, and NHEJ repair-related proteins in overexpressing HIF-1α A549 cell, thereby enhancing radiosensitivity in NSCLC.

CONCLUSION

This study provides an in-depth exploration of the radiosensitisation effect of GQBZD and provides an important experimental basis for the study of Chinese medicine in the field of cancer radiosensitisation, and further extends the extensibility of GQBZD on the basis of the previous study.

Radiotherapy-immunomodulated nanoplatform triggers both hypoxic and normoxic tumor associated antigens generation for robust abscopal effect and sustained immune memory

Radiotherapy (RT) induced abscopal effect has garnered substantial attention, nevertheless, it is rarely observed in clinics, due to the tumor hypoxia-related radioresistance, inadequate immune stimulation, and immunosuppressive tumor microenvironment. Herein, we construct a radiotherapy-immunomodulated nanoplatform (THUNDER), which synergizes with RT and greatly triggers the generation of both hypoxic and normoxic tumor cells-derived tumor-associated antigens (TAAs), resulting in robust abscopal effect and sustained immune memory. THUNDER exhibits prolonged blood circulation and high tumor retention capacity. When combined with RT, THUNDER effectively destructs both hypoxic and normoxic tumor cells, facilitating the substantial release of TAAs from both cell types, which further promotes the maturation of dendritic cells (DCs), thus forming powerful immune stimulation and initiating systemic anti-tumor immunity. In murine models, the combination of THUNDER and RT efficiently suppresses the growth of triple-negative breast cancer. In addition, the further combination with PD-L1 blockade yields noteworthy suppression of distant metastasis and tumor recurrence, resulting in a 5.2-fold augmentation in CD8+ T lymphocytes within distant tumors and a 2.8-fold increase in effector memory T cells in the spleen. In conclusion, the radiotherapy-immunomodulated nanoplatform presents an effective strategy for combating tumor metastases and recurrence by eliciting both hypoxic and normoxic TAAs, offering a significant avenue for radioimmunotherapy.

Clinical translation of ultra-high dose rate flash radiotherapy: Opportunities, challenges, and prospects

Ultra-high dose rate flash radiotherapy (FLASH-RT) has attracted wide attention in the field of radiotherapy in recent years. For FLASH-RT, radiation is delivered at a very high dose rate [usually thousands of times compared with conventional radiotherapy (CONV-RT)] in an extremely short time. This novel irradiation technique shows a protective effect on normal tissues, also known as the flash effect. At the same time, FLASH-RT is comparable to CONV-RT in terms of tumor-killing efficacy. As basic research dedicates to uncover the mechanisms by which FLASH-RT reduces radiation-induced normal tissue damage, clinical trials of FLASH-RT have been gradually conducted worldwide. This article systematically reviews the evidence of the feasibility and safety of FLASH-RT in clinical practice and offers insights into the future translation of this technology in clinic.

Subcellular functions of tau mediate repair response and synaptic homeostasis in injury

Injury responses in terminally differentiated cells such as neurons are tightly regulated by pathways aiding homeostatic maintenance. Cancer patients subjected to neuronal injury in brain radiation experience cognitive declines similar to those seen in primary neurodegenerative diseases. Numerous studies have investigated the effect of radiation in proliferating cells of the brain, yet the impact in differentiated, post-mitotic neurons, especially the structural and functional alterations remain largely elusive. We identified that microtubule-associated tau is a critical player in neuronal injury response via compartmentalized functions in both repair-centric and synaptic regulatory pathways. Ionizing radiation-induced injury acutely induces an increase in phosphorylated tau in the nucleus where it directly interacts with histone 2AX (H2AX), a DNA damage repair (DDR) marker. Loss of tau significantly reduced H2AX phosphorylation after irradiation, indicating that tau may play an important role in the neuronal DDR response. We also observed that loss of tau increases eukaryotic elongation factor levels, a positive regulator of protein translation after irradiation. This initial response cascades into a significant increase in synaptic proteins, resulting in disrupted homeostasis. Downstream, the novel object recognition test showed a decrease in learning and memory in tau-knockout mice after irradiation, and electroencephalographic activity contained increased delta and theta band oscillations, often seen in dementia patients. Our findings demonstrate tau's previously undefined, multifunctional role in acute responses to injury, ranging from DDR response in the nucleus to synaptic function within neurons. Such knowledge is vital to develop therapeutic strategies targeting neuronal injury in cognitive decline for at risk and vulnerable populations.

Organic Radiosensitizer with Aggregation-Induced Emission Characteristics for Tumor Ablation through Synergistic Apoptosis and Immunogenic Cell Death

Inspired by the clinical application of thermotherapy to promote the efficacy of radiotherapy, this study demonstrates the multimodal diagnostic application of pure organic nanoparticles in the combined treatment of tumors through imaging and photothermal properties. The nanoparticles developed in this study demonstrated unique properties and multiple functionalities, including excellent photostability and thermostability, strong fluorescence emission in the near-infrared-II (NIR-II) region, extremely high photothermal conversion efficiency, good biocompatibility, significant radiosensitizing properties, and effective tumor site accumulation. In vitro and in vivo evaluations demonstrated that these nanoparticles are ideal candidates for synergistic photothermal radiotherapy guided by NIR-II fluorescence, NIR-I photoacoustic, and photothermal trimodal imaging. They act as radiosensitizers by alleviating the hypoxic tumor microenvironment, modulating the cell cycle, and inducing apoptosis and immunogenic cell death during radiotherapy, which may provide a potential approach for the clinical treatment of tumors.

A Metformin-Based Multifunctional Nanoplatform as a DNA Damage Amplifier for Maximized Radio-Immunotherapy to Overcome Radiotherapy Resistance

Radiotherapy (RT) has been highlighted to be an effective strategy for antitumor immunity activation by causing direct DNA damages, but it generally suffers from low response rates due to the compromised cytosolic DNA (cDNA) recognition by cyclic GMP-AMP synthase (cGAS). Simultaneous DNA repair and clearance system regulation for enhanced cDNA accumulation is a useful approach to improve immune response rates, which remains seldom reported to our knowledge. Here, we report the construction of a metformin (MET)-based multifunctional nanocomplex, CS-MET/siTREX1 (CSMT), consisting of biguanide-decorated CS (CS-MET) as the vector and 3'-5' DNA exonuclease TREX1 siRNA (siTREX1) as the therapeutic gene for RT-induced antitumor immunity enhancement by amplifying the initial DNA damage signals. The uniqueness of this study is the development of CSMT as a specific DNA damage amplifier to promote cDNA accumulation for maximizing radio-immunotherapy and circumventing RT resistance. Specifically, the CSMT nanocomplexes show not only enhanced gene transfection efficiency by MET modification but also synergistic therapeutic effects including MET's inhibition on DNA repair and siTREX1's attenuation on cDNA clearance, which leads to the greatest inhibitory effect in a Hepa1-6 proximal/distal tumor model with a high tumor growth inhibition (TGI) value of 99.1% for the primary tumor and significantly compromised distal tumor growth by inducing immunogenic cell death (ICD), promoting tumor-associated neutrophil (TAN) polarization, and stimulating tumor-specific memory T-cell generation. Overall, the CSMT nanocomplexes developed herein hold great translatable promises for overcoming RT resistance in clinics.

Conversion of Ku80 K568 crotonylation to SUMOylation facilitates DNA non-homologous end joining and cancer radioresistance

Chemo-/radioresistance of malignant tumors hampers cancer control and increases patient mortality. Efficient repair of damaged DNA is critical for the maintenance of genomic integrity and fidelity of genetic information. In reverse, increased DNA repair capability in cancer cells contributes to chemo-/radioresistance of malignant tumors. DNA double-strand break (DSB) is the most serious DNA damage and is also the principal molecular basis of radiotherapy. Upon DNA damage, the Ku80 is recruited and forms a critical DNA-PK complex at the DSB sites with Ku70 and the catalytic subunit (DNA-PKcs) to initiate DNA repair. How DNA-PK is assembled and activated is not fully understood. Based on the identification of radiation-reduced Ku80 K568 crotonylation through quantitative global lysine crotonylome analysis, we reveal that Ku80 K568 is crotonylated by p300-CBP-associated factor (PCAF). Upon DNA damage, the K568cr is decrotonylated by HDAC8 (Histone deacetylase 8). Decrotonylation of K568cr empties this site for the subsequent SUMOylation of Ku80 by CBX4. The conversion of Ku80 from K568 crotonylation to SUMOylation facilitates the assembly of DNA-PK complex and autophosphorylation of DNA-PKcs S2056, consequently activating the DSB repair. Moreover, mutation disrupting the post-translational modification (PTM) of Ku80 K568 site sensitizes cancer cells to radiotherapy in tumor-bearing nude mice models. This study elucidates the conversion model between two different forms of PTMs in the regulation of DNA-PK complex assembly and DSB repair, highlighting this model's potential in controlling chemo-/radioresistance of malignant tumors, as well as expands the atlas of therapeutic targets.

Establishment and characterization of NCC-PS2-C1: a novel cell line of high-grade pleomorphic spindle cell sarcoma, most consistent with myxofibrosarcoma

Pleomorphic sarcoma (PS) is a heterogeneous group of malignant mesenchymal tumors that lack specific histological differentiation. PS is characterized by genetic instability and diversity and unique histological features such as pronounced morphologic pleomorphism. PS is one of the most common soft tissue sarcomas. Complete surgical resection remains the only curative treatment and is often combined with neoadjuvant radiotherapy. Effective systemic chemotherapy is yet to be established, and PS frequently recurs locally and metastasizes to the lungs. Patient-derived cancer cell lines are invaluable tools for basic and preclinical research for developing novel chemotherapies. Herein, we report a high-grade pleomorphic spindle cell sarcoma, most consistent with myxofibrosarcoma cell line, NCC-PS2-C1, which was derived from a primary tumor specimen. NCC-PS2-C1 cells exhibited a range of copy number alterations. This cell line demonstrated consistent proliferation, spheroid formation, and invasive capabilities in vitro. Drug screening using NCC-PS2-C1 cells revealed that cobimetinib, crenolanib, and ixazomib were effective against PS. In conclusion, we established NCC-PS2-C1 cells from primary tumors of PS. This cell line is a valuable resource for developing novel chemotherapies.

Verteporfin-Mediated In Situ Nanovaccine Based on Local Conventional-Dose Hypofractionated Radiotherapy Enhances Antitumor and Immunomodulatory Effect

In situ radiotherapy is the most successful cytotoxic therapy available for the treatment of solid tumors, while high-dose radiotherapy per fraction is not yet widely and reliably used. To some extent, the major considerations of the disappointing results are on the risk of high-dose irradiation-induced damage to the surrounding normal tissues and the difficulty in distant metastasis control. To break these restraints, a gelatinase-responsive amphiphilic methoxypolyethyleneglycol-PVGLIG-polycaprolactone (mPEG-PVGLIG-PCL) nanoparticles' loading verteporfin (N@VP), a special photosensitizer that can also be excited by X-rays to produce cytotoxic singlet oxygen and greatly enhance radiotherapy efficacy, is prepared in this study. Herein, it is shown that the formed N@VP combined with conventional-dose radiation therapy (RT, 2 Gy (gray, a radiation dose unit)) can realize an antitumor effect no less than high-dose RT (8 Gy) and minimize radiation dose necessary to achieve local tumor control. Moreover, this radiosensitive nanosystem can exert excellent systemic antitumor immunity and abscopal effect, providing a preferable "in situ vaccine" strategy based on conventional-dose RT to achieve efficient systemic management of distant tumor metastasis. When combined with immunotherapy, this novel strategy for radiosensitization results in better immunotherapy sensitivity by stimulating significant immunogenic tumor cell death and synergistic antitumor immune responses.

Multifaceted roles of OCT4 in tumor microenvironment: biology and therapeutic implications

OCT4 (Octamer-binding transcription factor 4, encoded by the POU5F1 gene) is a master transcription factor for maintaining the self-renewal and pluripotency of pluripotent stem cells, as well as a pioneer factor regulating epigenetics-driven cell reprogramming and cell fate conversion. It is also detected in a variety of cancer tissues and particularly in a small subpopulation of cancer cells known as cancer stem cells (CSCs). Accumulating evidence has revealed that CSCs are a dynamic population, exhibiting shift between multipotency and differentiation states, or quiescence and proliferation states. Such cellular plasticity of CSCs is profoundly influenced by dynamic interplay between CSCs and the tumor microenvironment (TME). Here, we review recent evidence showing that OCT4 expressed in CSCs plays a multifaceted role in shaping the TME by interacting with the cellular TME components, including cancer-associated fibroblasts, tumor endothelial cells, tumor-infiltrating immune cells, as well as the non-cellular TME components, such as extracellular matrix (ECM), metabolites, soluble factors (e.g., growth factors, cytokines and chemokines), and intra-tumoral microbiota. Together, OCT4 regulates crucial processes encompassing ECM remodeling, epithelial-mesenchymal transition, metabolic reprogramming, angiogenesis, and immune responses. The complex and bidirectional interactions between OCT4-expressing CSCs and the TME create a supportive niche for tumor growth, invasion, and resistance to therapy. Better understanding OCT4's roles in such interactions can provide deeper insights into potential therapeutic strategies and targets for disrupting the supportive environment of tumors. The emerging therapies targeting OCT4 in CSCs might hold promise to resensitize therapeutic-resistant cancer cells, and to eradicate all cancer cells when combined with other therapies targeting the bulk of differentiated cancer cells as well as the TME.

The dual HDAC/PI3K inhibitor CUDC-907 inhibits the growth and proliferation of MYC-driven Group 3 medulloblastoma

Metastatic Group 3 medulloblastoma (G3 MB) have been shown in several studies to be very high risk, particularly those harboring MYC amplification. More effective therapies are especially important for these patients. CUDC-907, a novel dual inhibitor targeting the MYC upstream pathway (HDAC/PI3K), shows significant antitumor efficacy across multiple cancer types. However, the antitumor effects and underlying mechanisms of CUDC-907 in MB, particularly in very high-risk MB, remain unexplored. In this study, we showed that MYC amplified G3 MB cells, patient-derived organoids and xenograft models were sensitive to CUDC-907. CUDC-907 inhibited MYC expression through the HDAC and PI3K pathways, and then induced G0/G1 phase arrest through the MYC-P21/P27-CDKs/cyclins axis. Furthermore, when CUDC-907 was combined with chemotherapeutic drug cisplatin, G0/G1 phase blocking effect was further enhanced. CUDC-907 in combination with radiotherapy (RT) inhibited DNA damage repair and increased DNA damage. These findings indicate that CUDC-907, either as a monotherapy or in combination with chemoradiotherapy, represents a promising therapeutic strategy for MYC amplified G3 MB, potentially influencing future clinical trials targeting this patient population.

The dilemma of nuclear mechanical forces in DNA damage and repair

Genomic stability, encompassing DNA damage and repair mechanisms, plays a pivotal role in the onset of diseases and the aging process. The stability of DNA is intricately linked to the chemical and mechanical forces exerted on chromatin, particularly within lamina-associated domains (LADs). Mechanical stress can induce DNA damage through the deformation and rupture of the nuclear envelope, leading to DNA bending and cleavage. However, DNA can evade such mechanical stress-induced damage by relocating away from the nuclear membrane, a process facilitated by the depletion of H3K9me3-marked heterochromatin and its cleavage from the lamina. When DNA double-stranded breaks occur, they prompt the rapid recruitment of Lamin B1 and the deposition of H3K9me3. Despite these insights, the precise mechanisms underlying DNA damage and repair under mechanical stress remain unclear. In this review, we explore the interplay between mechanical forces and the nuclear envelope in the context of DNA damage, elucidate the molecular pathways through which DNA escapes force-induced damage, and discuss the corresponding repair strategies involving the nuclear cytoskeleton. By summarizing the mechanisms of force-induced DNA damage and repair, we aim to underscore the potential for developing targeted therapeutic strategies to bolster genomic stability and alleviate the impacts of aging and disease.

Rational design of alternative treatment options for radioresistant rectal cancer using patient-derived organoids

BACKGROUND

Resistance to radiation therapy is a common challenge in the field of oncology. Cancer cells with an increased ability to effectively repair DNA or cells with higher levels of antioxidants are more resistant to radiation. As cancer cells rely on these traits for survival, they may offer vulnerabilities that could be exploited.

METHODS

In the current study, rectal cancer organoids that showed different responses to radiation treatment were identified. RNA sequencing was used to compare radioresistant and radiosensitive organoids. In vitro combination drug screens were performed. The selection of drugs was guided by the RNA sequencing results.

RESULTS

Radioresistant organoids exhibited superior transcriptional adaptability and activated more DNA repair pathways when irradiated. Additionally, radioresistant organoids displayed enhanced antioxidant metabolism, including pathways related to the detoxification of reactive oxygen species and the synthesis of glutathione. Combinatorial drug screens identified the combination of RRx-001 (an inducer of oxidative stress) with GCLC inhibitor BSO as a highly effective and synergistic drug combination in killing radioresistant organoids. CRISPR-CAS-mediated knockout of GCLC sensitised organoids to RRx-001.

CONCLUSION

Combining RRx-001 with the inhibition of GCLC may be a promising alternative treatment strategy in radioresistant rectal cancer.

Synthetic selenomelanin nanoparticles radio-sensitize non-melanocytic lung cancer (A549) cells by promoting G2/M arrest

Recent studies have postulated the natural existence of selenomelanin and its role in the radio-protection of healthy cells. The present study aimed to understand its radio-modulatory activity in non-melanocytic cancerous (A549) cells of lung origin. Briefly, selenomelanin was synthesized under laboratory conditions following the previously reported methodology. The various spectroscopic (electron paramagnetic resonance, X-ray photoelectron spectroscopy, atomic absorption spectroscopy, transmission electron microscopy and dynamic light scattering) analyses confirmed the formation of selenomelanin nanoparticles. The short-term (72 h) and long-term (14 days) toxicity profiling of selenomelanin by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) and clonogenic assays respectively revealed its half maximal inhibitory concentrations (IC50) of 72.03 ± 7.13 μg/ml and 0.85 ± 0.16 μg/ml respectively in A549 cells and of 81.56 ± 1.63 μg/ml and > 5 μg/ml respectively in healthy lung fibroblast (WI26) cells. Further, pre-treatment of selenomelanin (at concentrations non-toxic for WI26 cells) selectively augmented the radiosensitivity of A549 cells. Finally, mechanistic investigations in A549 cells revealed that selenomelanin increased the levels of reactive oxygen species, DNA damage and modulated the phospho-levels of CHK1 and CHK2 (effectors of cell cycle arrest) in the irradiated cells to favour G2/M arrest followed by cleavage of caspase 3 (effector of apoptosis). Together, the present study proposes the novel application of selenomelanin as a radiosensitizer to enhance the efficacy of radiotherapy in cancerous cells of lung origin.

Breaking barriers: harnessing hypofractionated radiotherapy to transform outcomes in low tumor mutation burden stage III non-small cell lung cancer - a retrospective study

Background

Non-Small Cell Lung Cancer (NSCLC) patients with low tumor mutational burden (TMB) showed low sensitive to conventional fractionated radiotherapy in our previous study. This study aimed to evaluate the efficacy and safety of hypofractionated radiotherapy (HFRT) in locally advanced NSCLC patients with low-TMB compared to conventional fractionated radiotherapy (CFRT).

Methods

We retrospectively analyzed clinical outcomes of 74 locally advanced NSCLC patients with low-TMB undergoing definitive radiotherapy from January 2017 to July 2023, with 31 patients received HFRT (received radiation doses of >2Gy and ≤5 Gy per fraction) and 43 received CFRT (received radiation doses of 1.8-2 Gy per fraction). Progression-free survival (PFS), overall survival (OS) and objective response rate (ORR) to radiotherapy was analyzed in the two groups. Univariate analysis was performed to assess the impact of clinical characteristics on PFS. We also analyzed PFS in subgroups receiving HFRT or CFRT combined with immunotherapy and chemotherapy.

Results

Survival analysis revealed the median PFS of 13 months in the HFRT group was significantly better than the 10 months in the CFRT group (p = 0.024). The 6-month and 12-month PFS rates were 80.6% and 61.3% for the HFRT group, versus 81.4% and 39.5% for the CFRT group, respectively. Median OS was 27 months in the HFRT group and 20 months in the CFRT group (p = 0.079). There were no statistically significant differences in major adverse events between the HFRT and CFRT groups (all p>0.05). In the subgroup receiving combined immunotherapy and chemotherapy, the median PFS was 10 months in the HFRT group and 9 months in the CFRT group (p = 0.092).

Conclusion

HFRT was superior to CFRT in prolonging PFS for patients with low-TMB locally advanced NSCLC. It was a safely and effective approach for these patients and was worth further prospective studies with larger sample sizes.

miR-208a-3p Targets PPP6C to Regulate the Progression of Radiation-Induced Pneumonia

Aims: Radiation-induced pneumonia (RP) is a common complication after radiotherapy for clinical thoracic tumors, and increasing evidence suggests that miRNAs have potential value in regulating radiation-induced lung injury. However, the potential mechanism is still obscure. Here, we evaluated the miRNAs-dependent mechanism involved in the progression of RP. Results: Our data showed that mmu-miR-208a-3p was consistently highly expressed in the lung tissue of irradiated mice. In vitro studies demonstrated that the expression of miR-208a-3p in cells was significantly increased after X-ray irradiation. Further mechanism studies indicated that radiation-induced upregulation of miR-208a-3p promoted inflammatory responses by suppressing the expression of protein phosphatase 6C (PPP6C) and activating the cyclic GMP-AMP synthase/stimulator of interferon genes protein pathway. Overexpression of PPP6C can alleviate radiation-induced DNA damage and excessive accumulation of ROS. It was also observed that PPP6C inhibited ionizing RP in vivo. Innovation and Conclusion: miR-208a-3p/PPP6C represents a potential therapeutic target for RP which needs to be verified by future clinical studies. Antioxid. Redox Signal. 00, 000-000.

Tailoring an intravenously injectable oncolytic virus for augmenting radiotherapy

Oncolytic viruses (OVs) combined with radiotherapy (RT) show promise but are limited by challenges such as poor intravenous delivery and insufficient RT-induced DNA damage. In this study, an oncolytic adenovirus (AD) formulation, RadioOnco (AD@PSSP), is developed to improve delivery, infectivity, immune response, and RT efficacy. The multifunctional polyethylenimine (PEI)-selenium-polyethylene glycol (PEG) (PSSP) enhances intravenous delivery, shields the virus from rapid clearance, and enables targeted delivery to tumor sites after RT. The exposed PEI enhances the infectivity of AD through electrostatic interactions, thereby increasing DNA damage after RT by inhibiting the expression of DNA repair proteins, such as CHEK1 and CDK1. Furthermore, AD-PEI captures and delivers RT-induced tumor-released antigens to lymph nodes, activating robust anti-tumor immune responses. Animal model data demonstrate that RadioOnco overcomes RT resistance, targets distant metastases, and promotes long-term immunity, addressing metastasis and recurrence. In summary, this intravenously injectable OV enhances RT synergy through surface modification with multifunctional materials.

Research progress in DNA damage response (DDR)-targeting modulators: From hits to clinical candidates

In recent years, synthetic lethality has been regarded as a sound example of cancer treatment. Identifying a growing number of synthetic lethality targets has led to a substantial broadening of the application of synthetic lethality, well beyond the PAPR inhibitors employed for treating tumors with BRCA1/2 deficiencies. Especially, molecular targets within the DDR have furnished inhibitor sources and have rapidly advanced to clinical trials. In this review, we summarize the DDR-associated synthetic lethality targets such as WRN, USP1, PARP, ATR, DNA-PK, PRMT5, POLQ, and WEE1. These targets allow for the development of targeted modulators like inhibitors and degraders. Additionally, we emphasize the rational design, advantages, and potential limitations. Furthermore, we outline the promising future of DDR-targeted drug development.

A Nanoradiosensitizer Potentiates Tumor Radiotherapy through JFK Inhibition and Hypoxia Alleviation

Radiotherapy (RT) is a primary treatment for breast cancer, but its effectiveness is often compromised by hypoxia and intrinsic resistance mechanisms. The F-box protein JFK is overexpressed in breast cancer and is associated with reduced radiosensitivity, but specific JFK inhibitors are currently unavailable. Herein, we developed spherical nanoparticles (SNP-JC) designed to co-deliver small interfering RNA targeting JFK and catalase to the tumor, aiming to silence JFK and alleviate hypoxia to overcome RT resistance. Positron emission tomography imaging demonstrated that SNP-JC efficiently accumulated in the tumors. SNP-JC significantly increased DNA damage in tumor cells after RT and promoted the immunogenic cell death. The combination of SNP-JC and RT activated CD8+ T cells and elicited a robust antitumor immunity, resulting in suppressed primary tumor growth and reduced lung metastasis. Our findings demonstrate that a nanoplatform capable of simultaneously silencing JFK and mitigating hypoxia can enhance tumor radiosensitivity, improve antitumor efficacy, and prevent metastasis.

Phosphoproteomic analysis of X-ray-irradiated planarians provides novel insights into the DNA damage response

Phosphorylation plays a crucial role in the cellular response to radiation and cancer therapies, yet phosphoproteomics studies in planarians remain underexplored despite the organism's remarkable regenerative capacities. This study utilized advanced ion mobility mass spectrometry for 4D-label-free quantitative proteomics to identify phosphorylation sites associated with irradiation in planarians. A total of 33,284 phosphorylation sites from 15,505 phosphorylated peptides and 4710 unique phosphoproteins were identified. In the sub-lethal dose irradiation group, 1695 phosphoproteins with 3483 phosphorylation sites exhibited significant changes, while exposure to lethal doses of radiation led to significant changes in 2308 phosphoproteins with 6112 phosphorylation sites, including many kinases, transcription factors, and cytoskeletal proteins. Functional enrichment analysis revealed that the altered phosphoproteins were primarily involved in transcription, RNA biosynthesis, mRNA processing regulation, and spliceosomal complex assembly. Functional validation of five differentially phosphorylated proteins revealed that their depletion impaired stem cell regeneration after irradiation by disrupting DNA repair, suggesting that these proteins are critical to planarian biology and their radiation response. By identifying the phosphorylation state and specific sites of planarian proteins, our study lays the foundation for further research on protein phosphorylation in the radiation-induced DNA damage response. In addition, our findings provide preliminary insights into the role of calnexin, a protein involved in interacting with newly synthesized N-linked glycoproteins, in planarians.

Predictors of Radiation Resistance and Novel Radiation Sensitizers in Head and Neck Cancers: Advancing Radiotherapy Efficacy

Radiation resistance in head and neck squamous cell carcinoma (HNSCC), driven by intrinsic and extrinsic factors, poses a significant challenge in radiation oncology. The key contributors are tumor hypoxia, cancer stem cells, cell cycle checkpoint activation, and DNA repair processes (homologous recombination and non-homologous end-joining). Genetic modifications such as TP53 mutations, KRAS mutations, EGFR overexpression, and abnormalities in DNA repair proteins like BRCA1/2 additionally affect radiation sensitivity. Novel radiosensitizers targeting these pathways demonstrate the potential to overcome resistance. Hypoxia-activated drugs and gold nanoparticles enhance the efficacy of radiotherapy and facilitate targeted distribution. Integrating immunotherapy, especially immune checkpoint inhibitors, with radiation therapy, enhances anti-tumor responses and reduces resistance. Epigenetic alterations, such as DNA methylation and histone acetylation, significantly influence radiation response, with the potential for sensitization through histone deacetylase inhibitors and non-coding RNA regulators. Metabolic changes linked to glucose, lipid, and glutamine metabolism influence radiosensitivity, uncovering new targets for radiosensitization. Human papillomavirus (HPV)-associated malignancies exhibit increased radiosensitivity relative to other tumors due to impaired DNA repair mechanisms and heightened immunogenicity. Furthermore, understanding the interplay between HPV oncoproteins and p53 functionality can enhance treatment strategies for HPV-related cancers. Using DNA damage response inhibitors (PARP, ATM/ATR), cell cycle checkpoint inhibitors (WEE1, CHK1/2), and hypoxia-targeted agents as radiosensitizing strategies exhibit considerable promise. Immunomodulatory approaches, including PD-1 and CTLA-4 inhibitors in conjunction with radiation, enhance anti-tumor immunity. Future directions emphasize personalized radiation therapy using genetics, sophisticated medication delivery systems, adaptive radiotherapy, and real-time monitoring. These integrated strategies seek to diminish radiation resistance and improve therapeutic efficacy in HNSCC.

A narrative review on the use of Green synthesized metallic nanoparticles for targeted cancer therapy

Cancer is a leading cause of death worldwide. While traditional and synthetic medical therapies are in place for cancer treatment, their effectiveness is hindered by various limitations, such as toxic side effects, limited availability, and high costs. In recent years, a promising alternative approach has emerged in the form of green-synthesized metallic nanoparticles (MNPs), which offer targeted cancer therapy. These nanoparticles (NPs) have garnered significant attention from cancer researchers owing to their natural or surface-induced anticancer properties, versatility of metals as agents, and eco-friendly nature. This approach may positively impact healthy cells surrounding the cancerous cells. Green-synthesized MNPs have gained popularity in cancer management because of their ease of handling in the laboratory and the affordability of starting materials compared to synthetic methods. This review analyzes green-synthesized MNPs for targeted cancer therapy, highlighting tumor-targeting strategies, synthesis methods, and clinical challenges. Unlike general reviews, it compares plant-, microbial-, and enzyme-mediated synthesis approaches, emphasizing their impact on nanoparticle stability, functionalization, and interactions with the tumor microenvironment for enhanced therapeutic efficacy.

CRISPR/Cas9 system: a novel approach to overcome chemotherapy and radiotherapy resistance in cancer

Cancer presents a global health challenge with rising incidence and mortality. Despite treatment advances in cancer therapy, radiotherapy and chemotherapy remained the most common treatments for all types of cancers. However, resistance phenotype in cancer cells leads to unsatisfactory results in the efficiency of therapeutic strategies. Therefore, researchers strive to propose effective solutions to overcome treatment failure, which requires a deep knowledge of treatment-resistant mechanisms. The progression and occurrence of tumors can be attributed to gene mutation. Over the past decade, the emergence of clustered regularly interspaced short palindromic repeats and CRISPR-associated protein 9 (CRISPR/Cas9) genome editing has revolutionized cancer research. This versatile technology enables cancer modeling, manipulation of specific DNA sequences, and genome-wide screening. CRISPR/Cas9 is an effective tool for identifying radio- and chemoresistance genes and offering potential adjunctive treatments to overcome tumor recurrence after chemo- and radiotherapy. This article aims to explain the potential of the CRISPR/Cas9 system in improving the effectiveness of chemo- and radiotherapy and ultimately overcoming treatment failure.

Dual-Mode Radiosensitization of Esophageal Squamous Cell Carcinoma via SOCS6-Loaded Virus-Inspired Manganese-Bismuth Bimetallic Oxide Nanoparticles

Radioresistance poses a significant obstacle to controlling the recurrence of esophageal squamous cell carcinoma (ESCC) during radiotherapy. It is urgent to develop innovative radiosensitization strategies to improve the prognosis of patients with ESCC. Here, a novel dual-mode radiosensitizer: a virus-inspired hollow mesoporous manganese-bismuth bimetallic oxide nanoparticles (vHMMn-Bi) encapsulating the radiosensitizing plasmids (suppressor of cytokine signaling 6, SOCS6) is developed, designed to significantly amplify ESCC radiotherapy under hypoxic conditions. After intravenous injection, the SOCS6@vHMMn-Bi nanoparticles can be efficiently delivered to the tumor site and rapidly invade tumor cells by virus-like surface-assisted adhesion. Under X-ray irradiation, the nanoparticles exhibits a unique dual-mode sensitization effect, encompassing exogenous and endogenous mechanisms, thereby significantly augmenting the ESCC radiotherapeutic effectiveness. First, the Bi2O3 within the shell can enhance the radiosensitivity owing to its robust X-ray attenuation characteristics. Second, the SOCS6 released from the interior can inhibit both HIF-1α and JAK2/STAT3 signaling pathways, triggering ROS upregulation and intensifying radiation-mediated DNA damage inside ESCC cells. Furthermore, the shell employs MnO2 to catalyze the decomposition of endogenous H2O2 to increase oxygen generation, alleviating hypoxia within the tumor microenvironment. These nanoparticles demonstrates considerable potential as dual-mode radiosensitizers with no systemic toxicity and low immunogenicity for amplifying radiotherapeutic efficacy in ESCC.

ALDH1A3 Regulates Cellular Senescence and Senescence-Associated Secretome in Prostate Cancer

Background: Radiotherapy is a key treatment for cancer, effectively controlling local tumor growth through DNA damage that induces senescence or apoptosis in cancer cells. However, radiotherapy can trigger complex cellular reactions, such as cell senescence, which is characterized by irreversible cell cycle arrest and the secretion of pro-inflammatory factors known as the senescent-associated secretory phenotype (SASP). Methods: This study investigates the regulatory role of ALDH1A3, a key enzyme implicated in cancer cell metabolism and radiotherapy resistance, in the induction of senescence and SASP. Using in vitro models, we demonstrate that ALDH1A3 knockdown accelerates cellular senescent-like phenotype while regulating the SASP through the cGAS-STING immune response pathway. Results: Our results indicate that while ALDH1A3 knockdown promotes senescence, it reduces the secretion of pro-inflammatory factors via inhibition of the cGAS-STING pathway, potentially mitigating SASP-related tumor progression. Conclusions: These findings provide insights into the molecular mechanisms underlying prostate cancer cell senescence and suggest that ALDH1A3 could be a potential therapeutic target to enhance the efficacy of radiotherapy while controlling the adverse effects of SASP.

Role of TDP2 in the repair of DNA damage induced by the radiomimetic drug Bleomycin

BACKGROUND

Bleomycin (Bleo) is a glycopeptide with potent antitumor activity that induces DNA double-strand breaks (DSBs) through free radical generation, similar to ionizing radiation (IR). Therefore, Bleo is considered a radiomimetic drug. However, differences in DNA repair mechanisms between IR- and Bleo-induced DNA damage have not been fully elucidated. Therefore, in the present study, we examined a panel of repair-deficient human TK6 cell lines to elucidate the relative contributions of individual repair factors.

RESULTS

Our comprehensive profiling indicated that both non-homologous end joining (NHEJ) and homologous recombination (HR) contributed to DSB repair induced by X-rays and Bleo. Furthermore, tyrosyl-DNA phosphodiesterase (TDP)-related repair was a significant factor for cellular sensitivity to Bleo treatment. TDP1-/-/TDP2-/- cells exhibited greater sensitivity to Bleo than TDP1-/- or TDP2-/- cells, but not to X-rays. In addition, we determined whether TDP2 is involved in the repair of Bleo-induced DSBs using a neutral comet assay. In TDP1-deficient cells, knockout of TDP2 resulted in a significant delay in the repair kinetics of DSBs induced by Bleo, but not by X-rays.

CONCLUSIONS

The contribution of the TDP-related pathway to DSB repair significantly differed between IR and radiomimetic drugs. The discovery of this novel TDP2-dependent repair of DSBs resulting from radiomimetic drug exposure indicates that TDP1 and TDP2 inhibition in combination with radiomimetic drugs represents a strategy for cancer treatment.

Wdr5-mediated H3K4 methylation facilitates HSPC development via maintenance of genomic stability in zebrafish

During fetal stage, hematopoietic stem and progenitor cells (HSPCs) undergo rapid proliferation with a tight control of genomic stability. Although histone H3 lysine 4 (H3K4) methylation has been reported to stabilize the genome in proliferating cells, its specific role in HSPC development remains elusive. In this study, we demonstrated that tryptophan-aspartic acid (WD) repeat protein 5 (Wdr5)-mediated H3K4 methylation is crucial for maintaining genomic stability of proliferating HSPCs in zebrafish embryos. Loss of wdr5 led to a severe reduction of HSPC pool in the caudal hematopoietic tissue, accompanied with attenuated H3K4 methylation level and evident p53-dependent apoptosis in the HSPCs. Mechanistically, Wdr5-mediated H3K4 methylation maintains genomic stability by inhibiting the formation of abnormal R-loops in the HSPCs, whereas accumulation of R-loops exacerbates DNA damage. Moreover, the absence of H3K4 trimethylation leads to an inactivated DNA damage response (DDR) pathway, which is deleterious to DNA damage repair and genomic stability. Subsequently, we found that DDR-associated genes, mutL homolog 1 and breast and ovarian cancer interacting helicase 1, are important to ensure HSPC survival, likely by stabilizing their genome. In summary, these findings reveal that Wdr5-mediated H3K4 methylation is essential for HSPC development through tight control of R-loop accumulation and DDR-associated program to ensure genomic stability and survival of proliferating HSPCs.

Discovery of a DNA repair-associated radiosensitivity index for predicting radiotherapy efficacy in breast cancer

Purpose

Radiotherapy is a cornerstone of breast cancer (BRCA) treatment. Accurately predicting tumor radiosensitivity is critical for optimizing therapeutic outcomes and personalizing treatment strategies. DNA repair pathways are key determinants of radiotherapy response. Thus, we aimed to develop a novel DNA repair-related radiosensitivity model and to identify potential targets for enhancing radiotherapy efficacy.

Methods

A retrospective study was conducted using data from 942 BRCA patients from TCGA database. A radiosensitivity model, comprising a radiosensitivity index, was developed using LASSO regression analysis. Patients were stratified into radiosensitive (RS) and radioresistant (RR) groups based on their radiosensitivity index (RSI). Associations between the RSI, clinicopathological parameters, and PD-L1 status were analyzed. The CIBERSORT and ESTIMATE algorithms were employed to characterize the immune landscape of the tumor microenvironment. The Tumor Immune Dysfunction and Exclusion (TIDE) algorithm and pRRophetic platform were used to predict treatment responses. Key genes identified in the radiosensitivity model were further validated using in vitro qRT-PCR experiments.

Results

We successfully constructed a radiosensitivity index incorporating 10 DNA repair-related genes. Patients in the RS group exhibited significantly better prognosis compared to the RR group, but this benefit was limited to those receiving radiotherapy. This survival benefit associated with the radiosensitivity signature was absent in patients who did not receive radiotherapy. The RS group displayed a distinct molecular profile characterized by enrichment of TGF-β signaling and protein secretion pathways, potentially contributing to enhanced radiosensitivity. Furthermore, the RS group exhibited increased infiltration of immune cells. Notably, the RS-PD-L1-high subgroup demonstrated the most favorable survival outcomes and highest immune cell infiltration, highlighting their potential responsiveness to immunotherapy. In addition, the RR group exhibited a distinct profile characterized by enrichment of DNA repair pathways and a heightened sensitivity to CDK and HER2 inhibitors. Conversely, this group displayed resistance to DNA-damaging drugs. These findings were supported by in vitro experiments using MCF-7 and radioresistant MCF-7/IR cell lines, confirming differential expression of key radiosensitivity index genes.

Conclusion

In conclusion, we established a radiosensitivity model for predicting radiotherapy benefit in breast cancer. Our study reveals a strong association between radiosensitivity, enhanced antitumor immunity, and potential immunotherapy benefit, particularly within the RS-PD-L1-high subgroup.

CHI3L1 mediates radiation resistance in colorectal cancer by inhibiting ferroptosis via the p53/SLC7A11 pathway

BACKGROUND

Radiotherapy is a key treatment for colorectal cancer (CRC), particularly rectal cancer; however, many patients are resistant to radiation. While it has been shown that CHI3L1 is associated with CRC progression, its specific function and regulatory mechanisms in radiation resistance remain unclear.

METHODS

The levels of CHI3L1 in CRC and normal tissue samples were obtained from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) datasets. To assess the effects of CHI3L1 on CRC cell proliferative, migratory, and invasive capacities, Cell Counting Kit-8 (CCK-8) and Transwell assays were performed. Radiation resistance in CRC cells with varying CHI3L1 expression levels was evaluated through colony formation assay. Western blot and immunofluorescence analyses were conducted to explore the correlation between CHI3L1 and p53 expression levels. Ferroptosis was assessed by determining reactive oxygen species (ROS), malondialdehyde (MDA), and glutathione (GSH) concentrations in cells with different CHI3L1 expression levels, and a xenograft mouse model was used to identify the molecular mechanisms of ferroptosis in vivo.

RESULTS

Significant CHI3L1 upregulated was observed in CRC tissues and was associated with promotion of malignant cell behaviors. The number of colonies in CHI3L1-overexpressing groups was significantly greater than that in the control groups following radiation, indicating increased radiation resistance in the former group. Furthermore, CHI3L1 overexpression was associated with p53 downregulation and elevated p53 ubiquitination. Notably, CHI3L1 inhibited the ferroptosis of CRC cells by suppressing p53 expression through the p53/SLC7A11 signaling pathway.

CONCLUSIONS

CHI3L1 overexpression promotes the proliferation, migration, invasion, and radiation resistance of CRC cells. Elevated CHI3L1 expression is associated with increased p53 ubiquitination and SLC7A11 upregulation. CHI3L1 promotes radiation resistance by suppressing ferroptosis in CRC cells through the p53/SLC7A11 axis.

DNA-PKcs Dysfunction Enhances the Antitumor Activity of Radioimmunotherapy by Activating the cGAS-STING Pathway in HNSCC

Introduction

Combining radiotherapy (RT) with immunotherapy for head and neck squamous cell carcinoma (HNSCC) has limited effectiveness due to the DNA damage repair (DDR) pathway activated by ionizing radiation. DNA-PK, encoded by the PRKDC gene, plays a key role in this repair. The potential improvement of radioimmunotherapy by inhibiting the DDR pathway is still unclear.

Methods

The effectiveness of different treatments on tumor growth and survival was tested using the C3H/HeN mouse tumor model. Flow cytometry analyzed treatment-induced immunophenotypic changes. In vitro, Western blot and PCR confirmed the impact of combining immunotherapy with RT on the cGAS-STING pathway after DNA-PKcs dysfunction.

Results

The combination of a DNA-PK inhibitor (NU7441), radiation therapy, and a PD-1 checkpoint inhibitor showed improved antitumor effects and extended survival in mice. Adding NU7441 into the RT and immunotherapy regimen increased CD8+ T cell infiltration. PRKDC alterations or DNA-PKcs dysfunction increased IR-induced DNA breaks, activating the cGAS-STING pathway and boosting the anti-tumor immune response.

Conclusion

These findings suggest that targeting the DDR pathway may represent a promising therapeutic strategy and biomarker to improve the efficacy of radioimmunotherapy in HNSCC.

A combined gene signature model for predicting radiotherapy response and relapse-free survival in laryngeal squamous cell carcinoma

BACKGROUND

Radioresistance is a major challenge in radiotherapy for laryngeal squamous cell carcinoma (LSCC), and there is currently no effective method to predict radiosensitivity in LSCC patients. This study aimed to establish a prediction model for radiotherapy response based on gene expression.

METHODS

The datasets of LSCC were obtained from the ENT department of Shanghai Ruijin Hospital and The Cancer Genome Atlas (TCGA). Lasso regression and Cox regression were used to establish the prediction model based on gene expression. Weighted gene coexpression network analysis (WGCNA) was used to analyze the correlation between gene expression and clinical characteristics. RT-qPCR was used to detect gene expression in tumor tissue to verify the accuracy of the prediction model.

RESULTS

Using a cohort of LSCC cases receiving radiotherapy collected in the TCGA database, the 3 protein-coding genes (PCGs) signature model was identified for the first time as the predictor of relapse-free survival and radiosensitivity in LSCC patients. And we explored the potential clinical value of 3 PCGs and screened out 2 long non-coding RNAs (lncRNAs) potential associated with 3 PCGs. More importantly, the LSCC cases collected by our department were used to preliminarily verify the predictive power of the 3 PCGs signature model for the radiosensitivity of LSCC, and the significant correlation between the expression levels of the 3 PCGs and the 2 lncRNAs.

CONCLUSION

We successfully establish a radiosensitivity prediction model based on the 3 PCGs Riskscore, which provides a theoretical basis for the decision-making of LSCC treatment options. Meantime, we preliminarily screen the potential associated lncRNAs of the 3 PCGs for further basic and clinical research.

The influence of the microbiome on radiotherapy and DNA damage responses

Colorectal cancer (CRC) is one of the most prevalent cancers in terms of diagnosis and mortality. Radiotherapy (RT) remains a mainstay of CRC therapy. As RT relies on DNA damage to promote tumor cell death, the activity of cellular DNA damage repair pathways can modulate cancer sensitivity to therapy. The gut microbiome has been shown to influence intestinal health and is independently associated with CRC development, treatment responses and outcomes. The microbiome can also modulate responses to CRC RT through various mechanisms such as community structure, toxins and metabolites. In this review we explore the use of RT in the treatment of CRC and the molecular factors that influence treatment outcomes. We also discuss how the microbiome can promote radiosensitivity versus radioprotection to modulate RT outcomes in CRC. Understanding the molecular interaction between the microbiome and DNA repair pathways can assist with predicting responses to RT. Once described, these connections between the microbiome and RT response can also be used to identify actionable targets for therapeutic development.

Nanomanaging Chronic Wounds with Targeted Exosome Therapeutics

Chronic wounds pose a significant healthcare challenge, impacting millions of patients worldwide and burdening healthcare systems substantially. These wounds often occur as comorbidities and are prone to infections. Such infections hinder the healing process, complicating clinical management and proving recalcitrant to therapy. The environment within the wound itself poses challenges such as lack of oxygen, restricted blood flow, oxidative stress, ongoing inflammation, and bacterial presence. Traditional systemic treatment for such chronic peripheral wounds may not be effective due to inadequate blood supply, resulting in unintended side effects. Furthermore, topical applications are often impervious to persistent biofilm infections. A growing clinical concern is the lack of effective therapeutic modalities for treating chronic wounds. Additionally, the chemically harsh wound microenvironment can reduce the effectiveness of treatments, highlighting the need for drug delivery systems that can deliver therapies precisely where needed with optimal dosages. Compared to cell-based therapies, exosome-based therapies offer distinct advantages as a cell-free approach for chronic wound treatment. Exosomes are of endosomal origin and enable cell-to-cell communications, and they possess benefits, including biocompatibility and decreased immunogenicity, making them ideal vehicles for efficient targeting and minimizing off-target damage. However, exosomes are rapidly cleared from the body, making it difficult to maintain optimal therapeutic concentrations at wound sites. The hydrogel-based approach and development of biocompatible scaffolds for exosome-based therapies can be beneficial for sustained release and prolong the presence of these therapeutic exosomes at chronic wound sites. Engineered exosomes have been shown to possess stability and effectiveness in promoting wound healing compared to their unmodified counterparts. Significant progress has been made in this field, but further research is essential to unlock their clinical potential. This review seeks to explore the benefits and opportunities of exosome-based therapies in chronic wounds, ensuring sustained efficacy and precise delivery despite the obstacles posed by the wound environment.

ATM is associated with the prognosis of colorectal cancer: a systematic review

Objective

Chemosensitivity and radiosensitivity are associated with the prognosis of colorectal cancer, and the expression of the ataxia-telangiectasia mutated (ATM) protein plays an essential role in these processes. The present study examined the relationship between ATM expression and the survival outcomes of colorectal cancer patients and explored the underlying mechanism and promising therapeutic strategies.

Method

A search including medical subject headings (MeSH), free terms, and combined words was conducted using Pubmed, EMBASE, and Cochrane. Studies had to meet the inclusion criteria as well as include processes such as data extraction and quality evaluation. The survival outcomes were assessed using hazard ratio (HR) and 95% confidence interval (CI). Heterogeneity, and publication bias were analyzed, and a P value <0.05 was considered statistically significant.

Results

Nine studies with 2883 patients were included in the meta-analysis. Low ATM expression level was related to poor overall survival (HR=0.542, 95% CI=0.447-0.637; P=0.000). Disease-free, progression-free, and recurrence-free survival rates were lower in patients with low ATM expression than in those with high ATM expression. There was no significant difference between Stage I-II and Stage III-IV colorectal cancer patients [risk ratio (RR)=1.173, 95% CI=0.970-1.417, P=0.690].

Conclusions

Low ATM expression level may be a marker of poor survival in colorectal cancer and contributes to resistance to therapy. Targeting related factors in these pathways to sensitize tumors to treatment is a potential therapeutic strategy, and monitoring ATM status could be a valuable guide independent of the immunotherapy or chemotherapy strategy used.

A Dual-Targeted Molecule for Disease-Activatable Proteolysis Targeting Chimeras and Targeted Radionuclide Therapy of Cancer

Proteolysis targeting chimeras (PROTACs) represent a cutting-edge approach for targeted protein degradation in cancer therapy, yet they face challenges such as poor pharmacokinetics and specificity issues, leading to undesirable off-target effects and limited antitumor potency. To address these issues, we introduce dual-targeted unimolecular theranostic probes (e.g., radioactive 177Lu-P-A and its cold counterpart natLu-P-A) for disease-activatable PROTACs in combination with targeted radionuclide therapy (TRT) against prostate cancer with high specificity and effectiveness. The probes achieve a cathepsin B (CTSB)-activatable pro-PROTAC moiety for precise degradation of bromodomain-containing protein 4 (BRD4) and a prostate-specific membrane antigen (PSMA)-targeted 177Lu-based TRT. Owing to the favorable pharmacokinetics and PSMA-mediated excellent targeting efficiency, the probe possesses high tumor imaging specificity and accumulation capacity of therapeutic units for highly effective PROTACs and TRT. In contrast, the free PROTACs unit (e.g., ARV-771) shows no observable therapeutic effect due to its poor targeting ability. Importantly, the BRD4 proteolysis by PROTAC activation can downregulate radiosensitivity-associated RAD51AP1 expression, synergistically enhancing the TRT effect and promoting apoptosis after combined therapy compared to individual treatment regimes. Additionally, the probe demonstrates high renal clearance, underscoring its biosafety for potential clinical translation. This study presents a potential approach for precise PROTACs combined with TRT for effective tumor therapy.

Effect of palliative radiotherapy and cyclin-dependent kinase 4/6 inhibitor on breast cancer cell lines

The most prevalent disease in the world and the main reason for women mortality from cancer is breast cancer. The recommended treatment for hormone receptor-positive metastatic breast cancer (MBC) is cyclin-dependent kinase 4/6 inhibitor (CDK4/6i), Abemaciclib. Radiotherapy (RT) is one of the main options to control breast cancer. This work intended to examine the impact of CDK 4/6i and palliative radiation on human breast cancer cell lines. Breast cancer cell lines (MCF7, MDA-MD-468, and MDA-MD-231) were treated with varying doses of Abemaciclib and left to incubate for 48 h. Different radiation doses were applied to the lines that had the best IC50. The intrinsic treatment objectives for MBC are presented in this study, along with the PI3K/AKT/mTOR pathway; CDK4, CDK6, and the NF-κβ/TGF-β pathway; BAX/BcL2, P53; caspase-3, caspase-6, caspase-7, caspase-8, and caspase-9; cytokeratin 18 (CK18); cycloxygenase-2 (COX2); IL-6; IL1β; matrix metalloproteinases (MMP2 and MMP9); and oxidative stress markers. The biochemical assays revealed that abemaciclib hindered the progression of breast cancer cells MDA-MB-231 and MCF-7 and enhanced RT (10 Gy) by provoking cell cycle arrest throughout the restraint of CDK4 and CDK6 expression and increasing apoptosis, in addition to decreasing the PI3K/AKT/mTOR and NF-κβ/TGF-β pathway expression; inhibiting CK18 and COX2 activity; boosting the protein concentration of BAX and P53; and decreasing Bcl-2, IL-6, IL-1β, MMP2, and MMP9, modulating oxidative stress markers. These results implied potential effects of radiation and CDK4/6i abemaciclib on breast cancer cell lines.

Graphene oxide-chloroquine conjugate induces DNA damage in A549 lung cancer cells through autophagy modulation

Autophagy is a highly regulated catabolic process by which unnecessary, dysfunctional, or damaged proteins and other cellular components are degraded and recycled to promote cellular differentiation, survival, and development. In response to endogenous or exogenous stresses, cancer cells use autophagy pathways for survival through activation of complex DNA damage repair (DDR) mechanisms. In the present study, we demonstrated the genotoxicity induced in A549 lung cancer cells by exposure to the GO-Chl nanoconjugate and elucidated the role of autophagy modulation in harnessing the DNA-damage response. GO-Chl causes loss of plasma membrane integrity, cell cycle arrest, and significant genotoxicity in A549 cells. Further, elevated expression of key autophagy proteins beclin-1, ATG-7, LC-3-I/II, and SQSTM1/p62 reveal that inhibition of autophagy plays a crucial role in regulating DDR capabilities of cancer cells. The results indicate that the interplay between DDR and autophagy pathways may open new paradigms for developing effective combinatorial nanoscale drug systems against multidrug-resistance cancers.

DNA-Capturing Manganese-Coordinated Chitosan Microparticles Potentiate Radiotherapy via Activating the cGAS-STING Pathway and Maintaining Tumor-Infiltrating CD8+ T-Cell Stemness

The radiotherapy-induced release of DNA fragments can stimulate the cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes (cGAS-STING) pathway to prime antitumor immunity, but this pathway is expected to be less potent because of the inefficient cytosolic delivery of negatively charged DNA fragments. In this study, manganese-coordinated chitosan (CS-Mn) microparticles with selective DNA-capturing capacity are concisely prepared via a coordination-directed one-pot synthesis process to potentiate the immunogenicity of radiotherapy. The obtained CS-Mn microparticles that undergo rapid disassembly under physiological conditions can selectively bind with DNA to form positively charged DNA-CS assemblies because of the strong electrostatic interaction between linear chitosan and DNA molecules. They thus enable efficient cytosolic delivery of DNA in the presence of serum to cooperate with Mn2+ to activate the cGAS-STING pathway in dendritic cells. Upon intratumoral injection, the CS-Mn microparticles markedly enhance the efficacy of radiotherapy against both irradiated and distal tumors in different tumor models via collectively promoting tumor-infiltrating CD8+ T-cell stemness and the activation of innate immunity. The radiosensitization effect of CS-Mn microparticles can be further augmented by concurrently applying anti-programmed cell death protein 1 (anti-PD-1) immunotherapy. This work highlights an ingenious strategy to prepare Trojan horse-like DNA-capturing microparticles as cGAS-STING-activating radiosensitizers for effective radioimmunotherapy.

Identification of Malignancy in Peritumoral Edema in Soft Tissue Sarcoma: A Novel Targeted Molecular Approach

BACKGROUND

Peritumoral edema on staging magnetic resonance imaging (MRI) is associated with higher local recurrence in soft tissue sarcoma (STS). This may relate to the presence of satellite malignant cells that are difficult to distinguish from benign atypia, leading to over- or undertreatment. This study evaluated a novel targeted molecular approach to identify malignancy in STS peritumoral planes as a means to improve personalized care.

METHODS

In the targeted molecular approach, whole-exome sequencing was employed to identify tumor-specific variants (TSVs), and peritumoral planes were assayed for malignancy, defined as two or more TSVs/plane, using droplet digital polymerase chain reaction (PCR). Feasibility was evaluated using a retrospective cohort (n = 8) in which planes with cellular atypia were tested. A prospective cohort (n = 8) then assayed all peritumoral planes with radiologic edema.

RESULTS

The targeted molecular approach identified malignancy in three of eight cases with cellular atypia of unknown significance (37.5%) and five of eight cases with peritumoral edema on staging MRI (62.5%). Peritumoral regions were heterogeneous; in none of the malignant cases did all sampled planes have evidence of tumor. Malignancy was also identified in regions without cellular atypia. Both cases with a local recurrence had molecular evidence of malignancy outside the main mass despite R0 margins.

CONCLUSION

This study describes a novel personalized approach to detect malignancy in peritumoral regions in STS and is the first to identify molecular evidence of tumor outside the main mass. While development of a clinical tool is underway, these findings support the current approach of treating all peritumoral edema as malignant.

Cell cycle dysregulation in cancer

Cancer is a systemic manifestation of aberrant cell cycle activity and dysregulated cell growth. Genetic mutations can determine tumor onset by either augmenting cell division rates or restraining normal controls such as cell cycle arrest or apoptosis. As a result, tumor cells not only undergo uncontrolled cell division but also become compromised in their ability to exit the cell cycle accurately. Regulation of cell cycle progression is enabled by specific surveillance mechanisms known as cell cycle checkpoints, and aberrations in these signaling pathways often culminate in cancer. For instance, DNA damage checkpoints, which preclude the generation and augmentation of DNA damage in the G1, S, and G2 cell cycle phases, are often defective in cancer cells, allowing cell division in spite of the accumulation of genetic errors. Notably, tumors have evolved to become dependent on checkpoints for their survival. For example, checkpoint pathways such as the DNA replication stress checkpoint and the mitotic checkpoint rarely undergo mutations and remain intact because any aberrant activity could result in irreparable damage or catastrophic chromosomal missegregation leading to cell death. In this review, we initially focus on cell cycle control pathways and specific functions of checkpoint signaling involved in normal and cancer cells and then proceed to examine how cell cycle control and checkpoint mechanisms can provide new therapeutic windows that can be exploited for cancer therapy. SIGNIFICANCE STATEMENT: DNA damage checkpoints are often defective in cancer cells, allowing cell division in spite of the accumulation of genetic errors. Conversely, DNA replication stress and mitotic checkpoints rarely undergo mutations because any aberrant activity could result in irreparable damage or catastrophic chromosomal missegregation, leading to cancer cell death. This review focuses on the checkpoint signaling mechanisms involved in cancer cells and how an emerging understanding of these pathways can provide new therapeutic opportunities for cancer therapy.

Development of novel epoxyketone macrocyclic peptidyl proteasome inhibitors through OPA-mediated one-step cyclization of unprotected peptides

Cyclization is a pivotal strategy for enhancing the drug-like characteristics of polypeptides. To develop potent and metabolically stable proteasome inhibitors, we generated a macrocyclic peptide skeleton using a straightforward and efficient cyclization strategy. Subsequent stability assessments confirmed the practicality of this approach. Leveraging this skeleton, we designed and synthesized a series of epoxyketone macrocyclic peptidyl proteasome inhibitors. Approximately half of these compounds showcased robust inhibitory potency, with IC50 values below 200 nM against chymotrypsin-like (ChT-L, β5) activity. Notably, compounds 6f, 6g, and 6m demonstrated pronounced anti-proliferative activities at low nanomolar concentrations against three hematoma cell lines (RPMI-8226, RS4;11, and MV-4-11) as well as the NCI-H1299 cell line. These findings highlight the potential of these cyclic peptides to bolster the stability of proteasome inhibitors, thereby providing valuable insights for the advancement of innovative proteasome inhibitor therapies.

Establishment and transcriptomic characteristics of radio-resistant meningioma cell lines

PURPOSE

Radio-resistance poses a significant challenge in meningioma treatment. This study aimed to establish radio-resistant meningioma cell lines and uncover molecular mechanisms driving radio-resistance to identify potential biomarkers and therapeutic targets.

METHODS

Radio-resistant meningioma cell lines (IOMM-Lee-RR, CH157-RR) were developed using a progressive radiation dose (cumulative 90 Gy). Cell morphology, radiosensitivity, apoptosis, viability, migration, invasion, cell cycle, and DNA damage repair were analyzed via clonogenic assays, flow cytometry, and Western blotting. Transcriptome sequencing was performed to identify differentially expressed genes (DEGs), followed by KEGG and GO enrichment analyses. Protein-protein interaction (PPI) analysis was conducted to identify hub genes. TK1 expression was further validated in a cohort of 350 meningiomas and the GSE189672 dataset.

RESULTS

Radio-resistant meningioma cell lines exhibited enhanced survival, reduced apoptosis, increased cell viability, and superior migratory and invasive abilities compared to parental cells. Under radiation, these cells showed G0/G1 phase accumulation and reduced G2/M phase arrest, along with enhanced DNA repair capacity, as evidenced by lower γ-H2AX expression and fewer DNA damage foci. Transcriptome analysis revealed significant enrichment in metabolic pathways, DNA repair, and cell cycle regulation. Among 34 hub genes identified, TK1 emerged as a key gene, being highly expressed in recurrent and high-grade meningiomas and positively correlated with Ki67. Analysis of the GSE189672 dataset confirmed TK1 as a poor prognostic factor associated with tumor recurrence.

CONCLUSION

Radio-resistant meningioma cells exhibit enhanced DNA repair, migration, invasion, and altered cell cycle dynamics. TK1 was identified as a promising biomarker and therapeutic target for overcoming radio-resistance in meningiomas.

The mechanism of high mobility group box-1 in the proliferation and macrophage polarization in esophageal squamous cell carcinoma cells

BACKGROUND

Previous studies showed that high mobility group box-1 (HMGB1) facilitates the initiation and progression of esophageal squamous cell carcinoma (ESCC), and the current research investigated the detailed mechanisms implicated.

METHODS

The impact of HMGB1 and IGFBP3 levels on the survival of ESCC was examined by plotting Kaplan-Meier (KM) curves based on the data collected from The Cancer Genome Atlas (TCGA). Quantitative real-time PCR (qRT-PCR) was performed to detect the expressions of HMGB1 in both human esophageal epithelial cells (HEEC) and ESCC cells. After cell transfection, the proliferation of ESCC cells was measured, and the cell metastasis was determined based on the levels of cadherins (CDHs) and Vimentin (VIM). Macrophage polarization was determined by calculating the mean fluorescence intensity (MFI) of CD206 and CD86. In addition, co-immunoprecipitation and immunoblotting were applied to evaluate the interaction between insulin-like growth factor binding protein 3 (IGFBP3)/DNA-dependent protein kinase catalytic subunit (DNA-PKcs) and HMGB1.

RESULTS

A high level of HMGB1 was predictive of an unfavorable prognosis of ESCC (p < 0.05). HMGB1 showed a higher expression in ESCC cells (p < 0.05), while knockdown of HMGB1 inhibited ESCC cell proliferation, downregulated the levels of CDH2 and VIM and upregulated the level of CDH1 (p < 0.05). In contrast, overexpressed HMGB1 showed the opposite effects (p < 0.05), suggesting the role of HMGB1 in the epithelial-mesenchymal transition (EMT) of ESCC. After the knockout of HMGB1, the MFI of CD86 was increased but that of CD206 was reduced, indicating the polarization towards M1 macrophages (p < 0.05). However, the results were reversed when HMGB1 was overexpressed (p < 0.05). Meanwhile, HMGB1 could interact with the IGFBP3/DNA-PKcs complex (p < 0.05). Low-expressed IGFBP3 was predictive of an unfavorable prognosis of ESCC, and IGFBP3 silencing promoted the proliferation of ESCC cells (p < 0.05). Besides, HMGB1 and IGFBP3 could act antagonistically in influencing the proliferation of ESCC cells and macrophage polarization.

CONCLUSIONS

Through in vitro experiments, this study found that HMGB1 was linked to the proliferation and polarization of macrophages in ESCC, providing novel evidence for the role of HMGB1 in ESCC development.

Radiotherapy resistance driven by Asparagine endopeptidase through ATR pathway modulation in breast cancer

BACKGROUND

Tumor resistance represents a major challenge in the current oncology landscape. Asparagine endopeptidase (AEP) overexpression correlates with worse prognosis and reduced overall survival in most human solid tumors. However, the underlying mechanisms of the connection between AEP and reduced overall survival in cancer patients remain unclear.

METHODS

High-throughput proteomics, cellular and molecular biology approaches and clinical data from breast cancer (BC) patients were used to identify novel, biologically relevant AEP targets. Immunoblotting and qPCR analyses were used to quantify protein and mRNA levels. Flow cytometry, confocal microscopy, chemical inhibitors, siRNA- and shRNA-silencing and DNA repair assays were used as functional assays. In-silico analyses using the TCGA BC dataset and immunofluorescence assays in an independent cohort of invasive ductal (ID) BC patients were used to validate the clinical relevance of our findings.

RESULTS

Here we showed a dual role for AEP in genomic stability and radiotherapy resistance in BC patients by suppressing ATR and PPP1R10 levels. Reduced ATR and PPP1R10 levels were found in BC patients expressing high AEP levels and correlated with worst prognosis. Mechanistically, AEP suppresses ATR levels, reducing DNA damage-induced cell death, and PPP1R10 levels, promoting Chek1/P53 cell cycle checkpoint activation, allowing BC cells to efficiently repair DNA. Functional studies revealed AEP-deficiency results in genomic instability, increased DNA damage signaling, reduced Chek1/P53 activation, impaired DNA repair and cell death, with phosphatase inhibitors restoring the DNA damage response in AEP-deficient BC cells. Furthermore, AEP inhibition sensitized BC cells to the chemotherapeutic reagents cisplatin and etoposide. Immunofluorescence assays in an independent cohort of IDBC patients showed increased AEP levels in ductal cells. These analyses showed that higher AEP levels in radioresistant IDBC patients resulted in ATR nuclear eviction, revealing AEPhigh/ATRlow protein levels as an efficient predictive biomarker for the stratification of radioresistant patients.

CONCLUSION

The newly identified AEP/ATR/PPP1R10 axis plays a dual role in genomic stability and radiotherapy resistance in BC. Our work provides new clues to the underlying mechanisms of tumor resistance and strong evidence validating the AEP/ATR axis as a novel predictive biomarker and therapeutic target for the stratification and treatment of radioresistant BC patients.

Loss of JAK1 Function Causes G2/M Cell Cycle Defects Vulnerable to Kif18a Inhibition

To gain insight into biological mechanisms that cause resistance to DNA damage, we performed parallel pooled genetic CRISPR-Cas9 screening for survival in high risk HNSCC subtypes. Surprisingly, and in addition to ATM, DNAPK, and NFKB signaling, JAK1 was identified as a driver of tumor cell radiosensitivity. Knockout of JAK1 in HNSCC increases cell survival by enhancing the DNA damage-induced G2 arrest, and both knockout and JAK1 inhibition with abrocitinib prevent subsequent formation of radiation-induced micronuclei. Loss of JAK1 function does not affect canonical CDK1 signaling but does reduce activation of PLK1 and AURKA, kinases that regulate both G2 and M phase progression. Correspondingly, JAK1 KO was found to cause mitotic defects using both EdU labeling and live cell imaging techniques. Given this insight, we evaluated Kif18a inhibition as an approach to exacerbate mitotic stress and enhance the efficacy of radiation. These studies establish Kif18a inhibition as a novel strategy to counteract therapeutic resistance to DNA damage mediated by G2 cell cycle arrest.

An Evaluation of the Potential Radiosensitization Effect of Spherical Gold Nanoparticles to Induce Cellular Damage Using Different Radiation Qualities

Global disparities in cancer prevention, detection, and treatment demand a unified international effort to reduce the disease's burden and improve outcomes. Despite advances in chemotherapy and radiotherapy, many tumors remain resistant to these treatments. Gold nanoparticles (AuNPs) have shown promise as radiosensitizers, enhancing the effectiveness of low-energy X-rays by emitting Auger electrons that cause localized cellular damage. In this study, spherical AuNPs of 5 nm and 10 nm were characterized and tested on various cell lines, including malignant breast cells (MCF-7), non-malignant cells (CHO-K1 and MCF-10A), and human lymphocytes. Cells were treated with AuNPs and irradiated with attenuated 6 megavoltage (MV) X-rays or p(66)/Be neutron radiation to assess DNA double-strand break (DSB) damage, cell viability, and cell cycle progression. The combination of AuNPs and neutron radiation induced higher levels of γ-H2AX foci and micronucleus formation compared to treatments with AuNPs or X-ray radiation alone. AuNPs alone reduced cellular kinetics and increased the accumulation of cells in the G2/M phase, suggesting a block of cell cycle progression. For cell proliferation, significant effects were only observed at the concentration of 50 μg/mL of AuNPs, while lower concentrations had no inhibitory effect. Further research is needed to quantify internalized AuNPs and correlate their concentration with the observed cellular effects to unravel the biological mechanisms of their radioenhancement.

Exploring the Therapeutic Potential of BRCA1 and BRCA2 as Targets in Canine Oncology: A Comprehensive Review of Their Role in Cancer Development and Treatment

Tumor diseases represent a significant global health challenge, impacting both humans and companion animals, notably dogs. The parallels observed in the pathophysiology of cancer between humans and dogs underscore the importance of advancing comparative oncology and translational research methodologies. Furthermore, dogs serve as valuable models for human cancer research due to shared environments, genetics, and treatment responses. In particular, breast cancer gene 1 (BRCA1) and breast cancer gene 2 (BRCA2), which are critical in human cancer, also influence the development and progression of canine tumors. The role of BRCA1 and BRCA2 in canine cancers remains underexplored, but its potential significance as therapeutic targets is strongly considered. This systematic review aims to broaden the discussion of BRCA1 and BRCA2 beyond mammary tumors, exploring their implications in various canine cancers. By emphasizing the shared genetic underpinnings between species and advocating for a comparative approach, the review indicates the potential of BRCA genes as targets for innovative cancer therapies in dogs, contributing to advances in human and veterinary oncology.