Cancer Radiosensitizers

Dextran 40 hybrid biomimetic bismuth-nanoflower designed for NIR II-triggered hypoxic tumor thermoradiotherapy via macrophage escape

At present, NIR-II-triggered photothermal biomedical applications are limited by complex synthesis reactions, mediocre photothermal conversion efficiency, and difficult degradation. Herein, we prepared biodegradable Bi flower-like nanoparticles (phospholipid-modified Bi nanoflowers, BNFs) with high photothermal conversion efficiency (∼33.52 %) in NIR-II by a simple method and then modified them with the red blood cell membrane and dextran 40 (DRBCM) to improve their in vitro stability, to escape macrophages clearance and to enhance tumor accumulation. Dextran coating onto the surface of particles as a dispersant shell stabilizes inorganic particles by maintaining the surface charges and creating steric repulsions upon compression of neighboring polymer chains. In vitro and in vivo experiments proved that combined thermoradiotherapy of DRBCM-BNFs exhibited significantly enhanced tumor inhibition efficacy than monotherapy with good biocompatibility and low toxicity due to its biodegradability. Furthermore, the mechanism studies demonstrated that DRBCM-BNFs could serve as a nano sensitizer to promote the thermoradiotherapy under NIR-II illumination and X-ray irradiation, by downregulating heat shock protein 70 (HSP70) and phosphorylated-p65 (p-p65) to reduce the thermal resistance and radioresistance of tumor cells and increasing the expression of apoptosis-related protein cleaved caspase-3. In conclusion, DRBCM-BNFs could be a promising green delivery platform for the sensitization of synergistic thermoradiotherapy.

Understanding radiation response and cell cycle variation in brain tumour cells using Raman spectroscopy

Radiation therapy is currently utilised in the treatment of approximately 50% of cancer patients. A move towards patient tailored radiation therapy would help to improve the treatment outcome for patients as the inter-patient and intra-patient heterogeneity of cancer leads to large differences in treatment responses. In radiation therapy, a typical treatment outcome is cell cycle arrest which leads to cell cycle synchronisation. As treatment is typically given over multiple fractions it is important to understand how variation in the cell cycle can affect treatment response. Raman spectroscopy has previously been assessed as a method for monitoring radiation response in cancer cells and has shown promise in detecting the subtle biochemical changes following radiation exposure. This study evaluated Raman spectroscopy as a potential tool for monitoring cellular response to radiation in synchronised versus unsynchronised UVW human glioma cells in vitro. Specifically, it was hypothesised that the UVW cells would demonstrate a greater radiation resistance if the cell cycle phase of the cells was synchronised to the G1/S boundary prior to radiation exposure. Here we evaluated whether Raman spectroscopy, combined with cell cycle analysis and DNA damage and repair analysis (γ-H2AX assay), could discriminate the subtle cellular changes associated with radiation response. Raman spectroscopy combined with principal component analysis (PCA) was able to show the changes in radiation response over 24 hours following radiation exposure. Spectral changes were assigned to variations in protein, specifically changes in protein signals from amides as well as changes in lipid expression. A different response was observed between cells synchronised in the cell cycle and unsynchronised cells. After 24 hours following irradiation, the unsynchronised cells showed greater spectral changes compared to the synchronised cells demonstrating that the cell cycle plays an important role in the radiation resistance or sensitivity of the UVW cells, and that radiation resistance could be induced by controlling the cell cycle. One of the main aims of cancer treatment is to stop the proliferation of cells by controlling or halting progression through the cell cycle, thereby highlighting the importance of controlling the cell cycle when studying the effects of cancer treatments such as radiation therapy. Raman spectroscopy has been shown to be a useful tool for evaluating the changes in radiation response when the cell cycle phase is controlled and therefore highlighting its potential for assessing radiation response and resistance.

Advanced Nitric Oxide Generating Nanomedicine for Therapeutic Applications

Nitric oxide (NO), a gaseous transmitter extensively present in the human body, regulates vascular relaxation, immune response, inflammation, neurotransmission, and other crucial functions. Nitrite donors have been used clinically to treat angina, heart failure, pulmonary hypertension, and erectile dysfunction. Based on NO's vast biological functions, it further can treat tumors, bacteria/biofilms and other infections, wound healing, eye diseases, and osteoporosis. However, delivering NO is challenging due to uncontrolled blood circulation release and a half-life of under five seconds. With advanced biotechnology and the development of nanomedicine, NO donors packaged with multifunctional nanocarriers by physically embedding or chemically conjugating have been reported to show improved therapeutic efficacy and reduced side effects. Herein, we review and discuss recent applications of NO nanomedicines, their therapeutic mechanisms, and the challenges of NO nanomedicines for future scientific studies and clinical applications. As NO enables the inhibition of the replication of DNA and RNA in infectious microbes, including COVID-19 coronaviruses and malaria parasites, we highlight the potential of NO nanomedicines for antipandemic efforts. This review aims to provide deep insights and practical hints into design strategies and applications of NO nanomedicines.

7-Geranyloxcycoumarin enhances radio sensitivity in human prostate cancer cells

BACKGROUND

Prostate cancer is the second most prevalent and the fifth deadliest cancer among men worldwide. To improve radiotherapy outcome, we investigated the effects of 7-geranyloxycoumarin, also known as auraptene (AUR), on radiation response of prostate cancer cells.

METHODS AND RESULTS

PC3 cells were pretreated with 20 and 40 µM AUR for 24, 48 and 72 h, followed by X-ray exposure (2, 4 and 6 Gy). After 72 h recovery, cell viability was determined by alamar Blue assay. Flow cytometric analysis was performed to assess apoptosis induction, clonogenic assay was carried out to investigate clonogenic survival, and the expression of P53, BAX, BCL2, CCND1 and GATA6 was analyzed by quantitative polymerase chain reaction (qPCR). Cell viability assay indicated that toxic effects of radiation was enhanced by AUR, which was also confirmed by increased numbers of apoptotic cells and reduced amount of survival fraction. The qPCR results demonstrated significant induction of P53 and BAX, while the expression of BCL2, GATA6, and CCND1 was significantly downregulated.

CONCLUSION

The findings of the present study indicated, for the first time, that AUR improved radio sensitivity in prostate cancer cells, and thus, has the potential to be used in future clinical trials.

Electron-Induced Decomposition of 5-Bromo-4-thiouracil and 5-Bromo-4-thio-2'-deoxyuridine: The Effect of the Deoxyribose Moiety on Dissociative Electron Attachment

When modified uridine derivatives are incorporated into DNA, radical species may form that cause DNA damage. This category of molecules has been proposed as radiosensitizers and is currently being researched. Here, we study electron attachment to 5-bromo-4-thiouracil (BrSU), a uracil derivative, and 5-bromo-4-thio-2'-deoxyuridine (BrSdU), with an attached deoxyribose moiety via the N-glycosidic (N1-C) bond. Quadrupole mass spectrometry was used to detect the anionic products of dissociative electron attachment (DEA), and the experimental results were supported by quantum chemical calculations performed at the M062X/aug-cc-pVTZ level of theory. Experimentally, we found that BrSU predominantly captures low-energy electrons with kinetic energies near 0 eV, though the abundance of bromine anions was rather low compared to a similar experiment with bromouracil. We suggest that, for this reaction channel, proton-transfer reactions in the transient negative ions limit the release of bromine anions.

Photodissociation of bromine-substituted nitroimidazole radiosensitizers

Heavy elements and some nitroimidazoles both exhibit radiosensitizing properties through different mechanisms. In an effort to see how the overall radiosensitivity might be affected when the two radiosensitizers are combined in the same molecule, we studied the gas-phase photodissociation of two brominated nitroimidazoles and a bromine-free reference sample. Synchrotron radiation was employed to initiate the photodynamics and energy-resolved multiparticle coincidence spectroscopy was used to study the ensuing dissociation. We observed the brominated samples releasing high amounts of potentially radiosensitizing fragments upon dissociation. Since bromination also increases the likelihood of the drug molecule being ionised per a given X-ray dose, we conclude that heavy-element substitution of nitroimidazoles appears to be a viable path towards new, potent radiosensitizer drugs.

Model-based assessment of combination therapies - ranking of radiosensitizing agents in oncology

BACKGROUND

To increase the chances of finding efficacious anticancer drugs, improve development times and reduce costs, it is of interest to rank test compounds based on their potential for human use as early as possible in the drug development process. In this paper, we present a method for ranking radiosensitizers using preclinical data.

METHODS

We used data from three xenograft mice studies to calibrate a model that accounts for radiation treatment combined with radiosensitizers. A nonlinear mixed effects approach was utilized where between-subject variability and inter-study variability were considered. Using the calibrated model, we ranked three different Ataxia telangiectasia-mutated inhibitors in terms of anticancer activity. The ranking was based on the Tumor Static Exposure (TSE) concept and primarily illustrated through TSE-curves.

RESULTS

The model described data well and the predicted number of eradicated tumors was in good agreement with experimental data. The efficacy of the radiosensitizers was evaluated for the median individual and the 95% population percentile. Simulations predicted that a total dose of 220 Gy (5 radiation sessions a week for 6 weeks) was required for 95% of tumors to be eradicated when radiation was given alone. When radiation was combined with doses that achieved at least 8 [Formula: see text] of each radiosensitizer in mouse blood, it was predicted that the radiation dose could be decreased to 50, 65, and 100 Gy, respectively, while maintaining 95% eradication.

CONCLUSIONS

A simulation-based method for calculating TSE-curves was developed, which provides more accurate predictions of tumor eradication than earlier, analytically derived, TSE-curves. The tool we present can potentially be used for radiosensitizer selection before proceeding to subsequent phases of the drug discovery and development process.

The benefit of co-targeting PARP-1 and c-Met on the efficacy of radiotherapy in wild type BRAF melanoma

Melanoma is known to be a radioresistant cancer. Melanoma radioresistance can be due to several factors such as pigmentation, antioxidant defenses and high Deoxyribonucleic acid (DNA) repair efficacy. However, irradiation induces intracellular translocation of RTKs, including cMet, which regulates response to DNA damage activating proteins and promotes DNA repair. Accordingly, we hypothesized that co-targeting DNA repair (PARP-1) and relevant activated RTKs, c-Met in particular, may radiosensitize wild-type B-Raf Proto-Oncogene, Serine/Threonine Kinase (WTBRAF) melanomas where RTKs are often upregulated. Firstly, we found that PARP-1 is highly expressed in melanoma cell lines. PARP-1 inhibition by Olaparib or its KO mediates melanoma cell sensitivity to radiotherapy (RT). Similarly, specific inhibition of c-Met by Crizotinib or its KO radiosensitizes the melanoma cell lines. Mechanistically, we show that RT causes c-Met nuclear translocation to interact with PARP-1 promoting its activity. This can be reversed by c-Met inhibition. Accordingly, RT associated with the inhibition of both c-Met and PARP-1 resulted in a synergistic effect not only on tumor growth inhibition but also on tumor regrowth control in all animals following the stop of the treatment. We thus show that combining PARP and c-Met inhibition with RT appears a promising therapeutic approach in WTBRAF melanoma.

Application of nano-radiosensitizers in combination cancer therapy

Radiosensitizers are compounds or nanostructures, which can improve the efficiency of ionizing radiation to kill cells. Radiosensitization increases the susceptibility of cancer cells to radiation-induced killing, while simultaneously reducing the potentially damaging effect on the cellular structure and function of the surrounding healthy tissues. Therefore, radiosensitizers are therapeutic agents used to boost the effectiveness of radiation treatment. The complexity and heterogeneity of cancer, and the multifactorial nature of its pathophysiology has led to many approaches to treatment. The effectiveness of each approach has been proven to some extent, but no definitive treatment to eradicate cancer has been discovered. The current review discusses a broad range of nano-radiosensitizers, summarizing possible combinations of radiosensitizing NPs with several other types of cancer therapy options, focusing on the benefits and drawbacks, challenges, and future prospects.

Recent advances in targeting myeloid-derived suppressor cells and their applications to radiotherapy

Myeloid-derived suppressor cells (MDSCs) are a group of heterogenous immature myeloid cells with potent immune suppressive properties that not only constrain anti-tumor immune activation and functions, promote tumor progression, but also contribute to treatment resistance and tumor relapse. Targeting MDSCs may be a promising new cancer treatment method, but there is still a problem of low treatment efficiency. Combined application with radiotherapy may be a potential method to solve this problem. Drug delivery systems (DDSs) provide more efficient targeted drug delivery capability and can reduce the toxicity and side effects of drugs. Recent advance in DDSs targeting development, recruitment, differentiation, and elimination of MDSCs have shown promising effect in reversing immune inhibition and in overcoming radiotherapy resistance. In this review, we systematically summarized DDSs applied to target MDSCs for the first time, and classified and discussed it according to its different mechanisms of action. In addition, this paper also reviewed the biological characteristics of MDSCs and their role in the initiation, progression, and metastasis of cancer. Moreover, this review also summarizes the role of DDSs targeting MDSCs in radiosensitization. Finally, the future development of DDSs targeting MDSCs is also prospected.

The Biochemistry and Effectiveness of Antioxidants in Food, Fruits, and Marine Algae

It is more effective to maintain good health than to regain it after losing it. This work focuses on the biochemical defense mechanisms against free radicals and their role in building and maintaining antioxidant shields, aiming to show how to balance, as much as possible, the situations in which we are exposed to free radicals. To achieve this aim, foods, fruits, and marine algae with a high antioxidant content should constitute the basis of nutritional elements, since natural products are known to have significantly greater assimilation efficiency. This review also gives the perspective in which the use of antioxidants can extend the life of food products, by protecting them from damage caused by oxidation as well as their use as food additives.

Docosahexaenoic Acid Attenuates Radiation-Induced Myocardial Fibrosis by Inhibiting the p38/ET-1 Pathway in Cardiomyocytes

PURPOSE

Radiation-induced myocardial fibrosis (RIMF) is a severe delayed complication of thoracic irradiation (IR). Endothelin-1 (ET-1) is critical in cardiac fibroblast activation, and docosahexaenoic acid (DHA) is protective against various cardiac diseases. This study aimed to explore the roles of ET-1 in RIMF and the potential of DHA in preventing RIMF.

METHODS AND MATERIALS

Hematoxylin and eosin, sirius red, and Masson trichrome staining were carried out to evaluate the histopathologic conditions in mouse models. Enzyme-linked immunosorbent assays were used to detect the concentration of ET-1 in serum and cell supernatants. Western blotting, immunofluorescence, and immunohistochemistry were used to assess the protein levels. The phenotypic alterations of cardiac fibroblasts were evaluated by cell proliferation/migration assays and α-smooth muscle actin (α-SMA) detection.

RESULTS

Radiation increased ET-1 expression and secretion by increasing p38 phosphorylation in cardiomyocytes, and ET-1 markedly promoted the activation of cardiac fibroblasts, which were characterized by enhanced fibroblast proliferation, migration, and α-SMA expression. Cardiomyocyte-derived ET-1 mediated radiation-induced fibroblast activation by targeting the PI3K-AKT and MEK-ERK pathways in fibroblasts. DHA suppressed ET-1 levels by blocking p38 signaling in cardiomyocytes and significantly attenuated the activation of cardiac fibroblasts induced by the IR/ET-1 axis. Importantly, DHA decreased collagen deposition and α-SMA expression, alleviating cardiac fibrosis caused by radiation in mouse models.

CONCLUSIONS

Our findings demonstrate that radiation facilitates cardiac fibroblast activation by enhancing p38/ET-1 signaling in cardiomyocytes, revealing the IR/p38/ET-1 regulatory axis in RIMF for the first time. DHA effectively inhibits fibroblast activation by targeting p38/ET-1 and can be recognized as a promising protective agent against RIMF.

Preparation of alginate coated Pt nanoparticle for radiosensitization of breast cancer tumor

Noble metals as high atomic number elements can localize X-ray radiation within tumor cells by exploiting different mechanisms. Here, alginate (Alg)-coated platinum nanoparticles (Pt@Alg) were synthesized, characterized, and implemented as a radiosensitizer to enhance X-ray therapeutic efficacy in breast cancer in vitro and in vivo. Alg not only improves the biocompatibility of the radioenhancer, but also stabilizes the nanoparticles. Pt@Alg was studied by different characterization methods including DLS, STEM, Fe-SEM, XRD, XPS, FT-IR and UV-Vis spectrophotometry. The nanosystem provided a higher level of intracellular ROS in malignant cells and enhanced cancer cell death under X-Ray irradiation. Clonogenic assay also demonstrated the radiosensitizing properties of the nanosystem, in vitro. In vivo result show tumor growth restraining properties of the nanosystem when it was administrated along with X-Ray irradiation. Histopathology results confirmed the impact of nanosystem and X-ray co-treatment, as well. Altogether, the importance of radiosensitizers for improving radiotherapy outcomes was highlighted.

Hypoxia-Responsive Aggregation of Gold Nanoparticles for Near-Infrared-II Photoacoustic Imaging-Guided Enhanced Radiotherapy

By directly harming cancer cells, radiotherapy (RT) is a crucial therapeutic approach for the treatment of cancers. However, the efficacy of RT is reduced by the limited accumulation and short retention time of the radiosensitizer in the tumor. Herein, we developed hypoxia-triggered in situ aggregation of nanogapped gold nanospheres (AuNNP@PAA/NIC NPs) within the tumor, resulting in second near-infrared window (NIR-II) photoacoustic (PA) imaging and enhanced radiosensitization. AuNNP@PAA/NIC NPs demonstrated increased accumulation and retention in hypoxic tumors, mainly due to the hypoxia-triggered aggregation. After aggregation of AuNNP@PAA/NIC NPs, the absorption of the system extended from visible light to NIR-II light owing to the plasmon coupling effects between adjacent nanoparticles. Compared to the normoxic tumor, the PA intensity at 1200 nm in the hypoxic tumor increased from 0.42 to 1.88 at 24 h postintravenous injection of AuNNP@PAA/NIC NPs, leading to an increase of 4.5 times. This indicated that the hypoxic microenvironment in the tumor successfully triggered the in situ aggregation of AuNNP@PAA/NIC NPs. The in vivo radiotherapeutic effect demonstrated that this hypoxia-triggered in situ aggregation of radiosensitizers significantly enhanced radiosensitization and thus resulted in superior cancer radiotherapeutic outcomes.

The potential of ferroptosis combined with radiotherapy in cancer treatment

Ferroptosis is a new form of regulatory cell death that is closely related to the balance of redox reactions and the occurrence and development of cancer. There is increasing evidence that inducing ferroptosis in cells has great potential in the treatment of cancer. Especially when combined with traditional therapy, it can improve the sensitivity of cancer cells to traditional therapy and overcome the drug resistance of cancer cells. This paper reviews the signaling pathways regulating ferroptosis and the great potential of ferroptosis and radiotherapy (RT) in cancer treatment and emphasizes the unique therapeutic effects of ferroptosis combined with RT on cancer cells, such as synergy, sensitization and reversal of drug resistance, providing a new direction for cancer treatment. Finally, the challenges and research directions for this joint strategy are discussed.

Oxygen-generating biocatalytic nanomaterials for tumor hypoxia relief in cancer radiotherapy

Radiotherapy (RT), the most commonly used treatment method in clinics, shows unique advantages such as strong penetration, high energy intensity, and low systemic side effects. However, in vivo tumor hypoxia seriously hinders the therapeutic effect of RT. Hypoxia is a common characteristic of locally advanced solid tumor microenvironments, which leads to the proliferation, invasion and metastasis of tumor cells. In addition, oxygen consumption during RT will further aggravate tumor hypoxia, causing a variety of adverse side effects. In recent years, various biocatalytic nanomaterials (BCNs) have been explored to regulate and reverse tumor hypoxia microenvironments during RT. In this review, the most recent efforts toward developing oxygen-generating BCNs in relieving tumor hypoxia in RT are focused upon. The classification, engineering nanocatalytical activity of oxygen-generating BCNs and combined therapy based on these BCNs are systematically introduced and discussed. The challenges and prospects of these oxygen-generating BCNs in RT applications are also summarized.

Effects of Au States in Thiol-Organosilica Nanoparticles on Enzyme-like Activity for X-ray Sensitizer Application: Focus on Reactive Oxygen Species Generation in Radiotherapy

In radiotherapy, the use of Au nanoparticles (Au NPs) has been proposed to enhance cell damage by X-ray irradiation. Although the role of Au in radiotherapy is not fully understood, the catalytic activity of Au has been actively studied in the industrial field. Moreover, owing to their enzyme-like activity and high biocompatibility in vitro and in vivo, Au NPs present significant potential for biological applications. In this study, we incorporated different Au states both on the surface and embedded in thiol-organosilica (thiol-OS/Au series) to investigate the efficiency of anticancer cell activity of Au in radiotherapy. The thiol-OS/Au series comprised different Au(I)/Au(0) ratios and Au NPs, and different sizes of Au NPs were embedded in thiol-OS/Au. These thiol-OS/Au series samples were evaluated for enzyme-like activities in reactive oxygen species (ROS) generation by X-ray irradiation. Thiol-OS/Au embedded with small Au NPs (AC600/thiol-OS/Au) exhibited peroxidase (POD)-like activity under acidic conditions. This POD-like activity improved ROS generation and cytotoxicity under X-ray irradiation. Furthermore, AC600/thiol-OS/Au exhibited catalase (CAT)-like activity under basic conditions and showed no cytotoxicity toward nonirradiated cells. These results revealed the efficiency of functionalizing with small Au NPs that possess pH-controlled POD- and CAT-like activity as a radiosensitizer. We compared the suitability of using Au with different states to obtain the thiol-OS/Au series samples for application as radiosensitizers. The findings of this study will aid the design of efficacious strategies for the Au nanostructure-based radiotherapy of cancer cells.

Potential Role of Natural Antioxidant Products in Oncological Diseases

Nutrition has a significant effect and a crucial role in disease prevention. Low consumption of fruit and vegetables and a sedentary lifestyle are closely related with the onset and development of many types of cancer. Recently, nutraceuticals have gained much attention in cancer research due to their pleiotropic effects and relatively non-toxic behavior. In fact, although in the past there have been conflicting results on the role of some antioxidant compounds as allies against cancer, numerous recent clinical studies highlight the efficacy of dietary phytochemicals in the prevention and treatment of cancer. However, further investigation is necessary to gain a deeper understanding of the potential anticancer capacities of dietary phytochemicals as well as the mechanisms of their action. Therefore, this review examined the current literature on the key properties of the bioactive components present in the diet, such as carotenoids, polyphenols, and antioxidant compounds, as well as their use in cancer therapy. The review focused on potential chemopreventive properties, evaluating their synergistic effects with anticancer drugs and, consequently, the side effects associated with current cancer treatments.

Tubastatin A potently inhibits GPX4 activity to potentiate cancer radiotherapy through boosting ferroptosis

Ferroptosis, an iron-dependent lipid peroxidation-driven programmed cell death, is closely related to cancer therapy. The development of druggable ferroptosis inducers and their rational application in cancer therapy are critical. Here, we identified Tubastatin A, an HDAC6 inhibitor as a novel druggable ferroptosis inducer through large-scale drug screening. Tubastatin A directly bonded to GPX4 and inhibited GPX4 enzymatic activity through biotin-linked Tubastatin A putdown and LC/MS analysis, which is independent of its inhibition of HDAC6. In addition, our results showed that radiotherapy not only activated Nrf2-mediated GPX4 transcription but also inhibited lysosome-mediated GPX4 degradation, subsequently inducing ferroptosis tolerance and radioresistance in cancer cells. Tubastatin A overcame ferroptosis resistance and radioresistance of cancer cells by inhibiting GPX4 enzymatic activity. More importantly, Tubastatin A has excellent bioavailability, as demonstrated by its ability to significantly promote radiotherapy-induced lipid peroxidation and tumour suppression in a mouse xenograft model. Our findings identify a novel druggable ferroptosis inducer, Tubastatin A, which enhances radiotherapy-mediated antitumor effects. This work provides a compelling rationale for the clinical evaluation of Tubastatin A, especially in combination with radiotherapy.

Emerging roles of Aurora-A kinase in cancer therapy resistance

Aurora kinase A (Aurora-A), a serine/threonine kinase, plays a pivotal role in various cellular processes, including mitotic entry, centrosome maturation and spindle formation. Overexpression or gene-amplification/mutation of Aurora-A kinase occurs in different types of cancer, including lung cancer, colorectal cancer, and breast cancer. Alteration of Aurora-A impacts multiple cancer hallmarks, especially, immortalization, energy metabolism, immune escape and cell death resistance which are involved in cancer progression and resistance. This review highlights the most recent advances in the oncogenic roles and related multiple cancer hallmarks of Aurora-A kinase-driving cancer therapy resistance, including chemoresistance (taxanes, cisplatin, cyclophosphamide), targeted therapy resistance (osimertinib, imatinib, sorafenib, etc.), endocrine therapy resistance (tamoxifen, fulvestrant) and radioresistance. Specifically, the mechanisms of Aurora-A kinase promote acquired resistance through modulating DNA damage repair, feedback activation bypass pathways, resistance to apoptosis, necroptosis and autophagy, metastasis, and stemness. Noticeably, our review also summarizes the promising synthetic lethality strategy for Aurora-A inhibitors in RB1, ARID1A and MYC gene mutation tumors, and potential synergistic strategy for mTOR, PAK1, MDM2, MEK inhibitors or PD-L1 antibodies combined with targeting Aurora-A kinase. In addition, we discuss the design and development of the novel class of Aurora-A inhibitors in precision medicine for cancer treatment.

Mechanisms of Nanoscale Radiation Enhancement by Metal Nanoparticles: Role of Low Energy Electrons

Metal nanoparticles are considered as highly promising radiosensitizers in cancer radiotherapy. Understanding their radiosensitization mechanisms is critical for future clinical applications. This review is focused on the initial energy deposition by short-range Auger electrons; when high energy radiation is absorbed by gold nanoparticles (GNPs) located near vital biomolecules; such as DNA. Auger electrons and the subsequent production of secondary low energy electrons (LEEs) are responsible for most the ensuing chemical damage near such molecules. We highlight recent progress on DNA damage induced by the LEEs produced abundantly within about 100 nanometers from irradiated GNPs; and by those emitted by high energy electrons and X-rays incident on metal surfaces under differing atmospheric environments. LEEs strongly react within cells; mainly via bound breaking processes due to transient anion formation and dissociative electron attachment. The enhancement of damages induced in plasmid DNA by LEEs; with or without the binding of chemotherapeutic drugs; are explained by the fundamental mechanisms of LEE interactions with simple molecules and specific sites on nucleotides. We address the major challenge of metal nanoparticle and GNP radiosensitization; i.e., to deliver the maximum local dose of radiation to the most sensitive target of cancer cells (i.e., DNA). To achieve this goal the emitted electrons from the absorbed high energy radiation must be short range, and produce a large local density of LEEs, and the initial radiation must have the highest possible absorption coefficient compared to that of soft tissue (e.g., 20-80 keV X-rays).

Novel strategies for tumor radiosensitization mediated by multifunctional gold-based nanomaterials

Radiotherapy (RT) is one of the most effective and commonly used cancer treatments for malignant tumors. However, the existing radiosensitizers have a lot of side effects and poor efficacy, which limits the curative effect and further application of radiotherapy. In recent years, emerging nanomaterials have shown unique advantages in enhancing radiosensitization. In particular, gold-based nanomaterials, with high X-ray attenuation capacity, good biocompatibility, and promising chemical, electronic and optical properties, have become a new type of radiotherapy sensitizer. In addition, gold-based nanomaterials can be used as a carrier to load a variety of drugs and immunosuppressants; in particular, its photothermal therapy, photodynamic therapy and multi-mode imaging functions aid in providing excellent therapeutic effect in coordination with RT. Recently, many novel strategies of radiosensitization mediated by multifunctional gold-based nanomaterials have been reported, which provides a new idea for improving the efficacy and reducing the side effects of RT. In this review, we systematically summarize the recent progress of various new gold-based nanomaterials that mediate radiosensitization and describe the mechanism. We further discuss the challenges and prospects in the field. It is hoped that this review will help researchers understand the latest progress of gold-based nanomaterials for radiosensitization, and encourage people to optimize the existing methods or explore novel approaches for radiotherapy.

Review: Mechanisms and perspective treatment of radioresistance in non-small cell lung cancer

Radiotherapy is the major treatment of non-small cell lung cancer (NSCLC). The radioresistance and toxicity are the main obstacles that leading to therapeutic failure and poor prognosis. Oncogenic mutation, cancer stem cells (CSCs), tumor hypoxia, DNA damage repair, epithelial-mesenchymal transition (EMT), and tumor microenvironment (TME) may dominate the occurrence of radioresistance at different stages of radiotherapy. Chemotherapy drugs, targeted drugs, and immune checkpoint inhibitors are combined with radiotherapy to treat NSCLC to improve the efficacy. This article reviews the potential mechanism of radioresistance in NSCLC, and discusses the current drug research to overcome radioresistance and the advantages of Traditional Chinese medicine (TCM) in improving the efficacy and reducing the toxicity of radiotherapy.

Gold Nanorods Inhibit Tumor Metastasis by Regulating MMP-9 Activity: Implications for Radiotherapy

Dysregulation of matrix metalloproteinase (MMP) is strongly implicated in tumor invasion and metastasis. Nanomaterials can interact with proteins and have impacts on protein activity, which provides a potential strategy for inhibiting tumor invasion and metastasis. However, the regulation of MMP activity by nanomaterials has not been fully determined. Herein, we have found that gold nanorods (Au NRs) are able to induce the change of the secondary structure of MMP-9 and thereby inhibit their activity. Interestingly, the inhibition of MMP-9 activity is highly dependent on the aspect ratio of Au NRs, and an aspect ratio of 3.3 shows the maximum inhibition efficiency. Molecular dynamics simulations combined with mathematical statistics algorithm reveal the binding behaviors and interaction modes of MMP-9 with Au NRs in atomic details and disclose the mechanism of aspect ratio-dependent inhibition effect of Au NRs on MMP-9 activity. Au NRs with an aspect ratio of 3.3 successfully suppress the X-ray-activated invasion and metastasis of tumor by inhibiting MMP-9 activity. Our findings provide important guidance for the modulation of MMP-9 activity by tuning key parameters of nanomaterials and demonstrate that gold nanorods could be developed as potential MMP inhibitors.

Tween-20-Modified BiVO4 Nanorods for CT Imaging-Guided Radiotherapy of Tumor

Oral cancer is the most common malignant tumor in the oral and maxillofacial region, which seriously threatens the health of patients. At present, radiotherapy is one of the commonly used methods for oral cancer treatment. However, the resistance of cancerous tissues to ionizing radiation, as well as the side effects of X-rays on healthy tissues, still limit the application of radiotherapy. Therefore, how to effectively solve the above problems is still a challenge at present. Generally speaking, elements with high atomic numbers, such as bismuth, tungsten, and iodine, have a high X-ray attenuation capacity. Using nanomaterials containing these elements as radiosensitizers can greatly improve the radiotherapy effect. At the same time, the modification of nanomaterials based on the above elements with the biocompatible polymer can effectively reduce the side effects of radiosensitizers, providing a new method for the realization of efficient and safe radiotherapy for oral cancer. In this work, we prepared Tween-20-modified BiVO₄ nanorods (Tw20-BiVO₄ NRs) and further used them in the radiotherapy of human tongue squamous cell carcinoma. Tw20-BiVO₄ NRs are promising radiosensitizers, which can generate a large number of free radicals under X-rays, leading to the damage of cancer cells and thus playing a role in tumor therapy. In cell experiments, radiotherapy sensitization of Tw20-BiVO₄ NRs significantly enhanced the production of free radicals in oral cancer cells, aggravated the destruction of chromosomes, and improved the therapeutic effect of radiotherapy. In animal experiments, the strong X-ray absorption ability of Tw20-BiVO₄ NRs makes them effective contrast agents in computed tomography (CT) imaging. After the tumors are located by CT imaging, it helps to apply precise radiotherapy; the growth of subcutaneous tumors in nude mice was significantly inhibited, confirming the remarkable effect of CT imaging-guided radiotherapy.

BAG1, MGMT, FOXO1, and DNAJA1 as potential drug targets for radiosensitizing cancer cell lines

BACKGROUND AND PURPOSE

Activation of some signaling pathways can promote cell survival and have a negative impact on tumor response to radiotherapy. Here, the role of differences in expression levels of genes related to the poly(ADP-ribose) polymerase-1 (PARP-1), heat shock protein 90 (Hsp90), B-cell lymphoma 2 (Bcl-2), and phosphoinositide 3-kinase (PI3K) pathways in the survival or death of cells following X-ray exposure was investigated.

METHODS

Eight human cell cultures (MCF-7 and MDA-MB-231: breast cancers; MCF-12A: apparently normal breast; A549: lung cancer; L132: normal lung; G28, G44 and G112: glial cancers) were irradiated with X-rays. The colony-forming and real-time PCR based on a custom human pathway RT² Profiler PCR Array assays were used to evaluate cell survival and gene expression, respectively.

RESULTS

The surviving fractions at 2 Gy for the cell lines, in order of increasing radioresistance, were found to be as follows: MCF-7 (0.200 ± 0.011), G44 (0.277 ± 0.065), L132 (0.367 ± 0.023), MDA-MB-231 (0.391 ± 0.057), G112 (0.397 ± 0.113), A549 (0.490 ± 0.048), MCF-12A (0.526 ± 0.004), and G28 (0.633 ± 0.094). The rank order of radioresistance at 6 Gy was: MCF-7 < L132 < G44 < MDA-MB-231 < A549 < G28 < G112 < MCF-12A. PCR array data analysis revealed that several genes were differentially expressed between irradiated and unirradiated cell cultures. The following genes, with fold changes: BCL2A1 (21.91), TP53 (8743.75), RAD51 (11.66), FOX1 (65.86), TCP1 (141.32), DNAJB1 (3283.64), RAD51 (51.52), and HSPE1 (12887.29) were highly overexpressed, and BAX (-127.21), FOX1 (-81.79), PDPK1 (-1241.78), BRCA1 (-8.70), MLH1 (-12143.95), BCL2 (-18.69), CCND1 (-46475.98), and GJA1 (-2832.70) were highly underexpressed in the MDA-MB-231, MCF-7, MCF-12A, A549, L132, G28, G44, and G112 cell lines, respectively. The radioresistance in the malignant A549 and G28 cells was linked to upregulation in the apoptotic, DNA repair, PI3K, and Hsp90 pathway genes BAG1, MGMT, FOXO1, and DNAJA1, respectively, and inhibition of these genes resulted in significant radiosensitization.

CONCLUSIONS

Targeting BAG1, MGMT, FOXO1, and DNAJA1 with specific inhibitors might effectively sensitize radioresistant tumors to radiotherapy.

Multifunctional tunable ZnFe2O4@MnFe2O4 nanoparticles for dual-mode MRI and combined magnetic hyperthermia with radiotherapy treatment

With the increase in non-communicable diseases, cancer is becoming one of the most lethal ailments of the coming decades. Significant progress has been made in the development of NPs that combine diagnostic and therapeutic properties in a single system. Multimodal NPs that sequentially perform MRI diagnostics with increased contrast and then act as synergistic agents for magnetic hyperthermia and radiotherapy can be considered as next-generation anticancer drugs. Thus, we propose a systematic study of composite theranostic ZnFe₂O₄@MnFe₂O₄ NPs for the first time. Two types of magnetic NPs with MnFe₂O₄ shell thicknesses of 0.5 (ZM0.5) and 1.7 nm (ZM3) were prepared via hydrothermal synthesis. Tuning the shell thickness was shown to influence the NP r₂ and r₁ relaxivities and allow T₁-T₂ dual-mode contrast agents to be obtained. A radiotherapy study demonstrated a significant dose factor enhancement (about 40%) for both NP types. The specific absorption rate of ZM3 in a 100 Oe alternating magnetic field with a frequency of 75 kHz was found to be 8 W g^-1, which results in heating up to 42 °C within a few seconds. This work presents high-performance multifunctional NPs capable of combining different diagnostic and therapeutic methods for a full course of treatment using only one type of NP.

A Cell-Penetrating Peptide Modified Cu2-xSe/Au Nanohybrid with Enhanced Efficacy for Combined Radio-Photothermal Therapy

Radiotherapy (RT) is one of the main clinical therapeutic strategies against cancer. Currently, multiple radiosensitizers aimed at enhancing X-ray absorption in cancer tissues have been developed, while limitations still exist for their further applications, such as poor cellular uptake, hypoxia-induced radioresistance, and unavoidable damage to adjacent normal body tissues. In order to address these problems, a cell-penetrating TAT peptide (YGRKKRRQRRRC)-modified nanohybrid was constructed by doping high-Z element Au in hollow semiconductor Cu_2-xSe nanoparticles for combined RT and photothermal therapy (PTT) against breast cancer. The obtained Cu_2-xSe nanoparticles possessed excellent radiosensitizing properties based on their particular band structures, and high photothermal conversion efficiency beneficial for tumor ablation and promoting RT efficacy. Further doping high-Z element Au deposited more high-energy radiation for better radiosensitizing performance. Conjugation of TAT peptides outside the constructed Cu_2-xSe/Au nanoparticles facilitated their cellular uptake, thus reducing overdosage-induced side effects. This prepared multifunctional nanohybrid showed powerful suppression effects towards breast cancer, both in vitro and in vivo via integrating enhanced cell penetration and uptake, and combined RT/PTT strategies.

Mechanisms of radioresistance and the underlying signaling pathways in colorectal cancer cells

Radiotherapy is one of the most common modalities for the treatment of a wide range of tumors, including colorectal cancer (CRC); however, radioresistance of cancer cells remains a major limitation for this treatment. Following radiotherapy, the activities of various cellular mechanisms and cell signaling pathways are altered, resulting in the development of radioresistance, which leads to therapeutic failure and poor prognosis in patients with cancer. Furthermore, even though several inhibitors have been developed to target tumor resistance, these molecules can induce side effects in nontumor cells due to low specificity and efficiency. However, the role of these mechanisms in CRC has not been extensively studied. This review discusses recent studies regarding the relationship between radioresistance and the alterations in a series of cellular mechanisms and cell signaling pathways that lead to therapeutic failure and tumor recurrence. Our review also presents recent advances in the in vitro/in vivo study models aimed at investigating the radioresistance mechanism in CRC. Furthermore, it provides a relevant biochemical basis in theory, which can be useful to improve radiotherapy sensitivity and prolong patient survival.

Application of nanomedicine in radiotherapy sensitization

Radiation therapy is an important component of cancer treatment. As research in radiotherapy techniques advances, new methods to enhance tumor response to radiation need to be on the agenda to enable enhanced radiation therapy at low radiation doses. With the rapid development of nanotechnology and nanomedicine, the use of nanomaterials as radiosensitizers to enhance radiation response and overcome radiation resistance has attracted great interest. The rapid development and application of emerging nanomaterials in the biomedical field offers good opportunities to improve the efficacy of radiotherapy, which helps to promote the development of radiation therapy and will be applied in clinical practice in the near future. In this paper, we discuss the main types of nano-radiosensitizers and explore their sensitization mechanisms at the tissue level, cellular level and even molecular biology and genetic level, and analyze the current status of promising nano-radiosensitizers and provide an outlook on their future development and applications.

Focused Ultrasound and Ultrasound Stimulated Microbubbles in Radiotherapy Enhancement for Cancer Treatment

Radiation therapy (RT) has been the standard of care for treating a multitude of cancer types. However, ionizing radiation has adverse short and long-term side effects which have resulted in treatment complications for decades. Thus, advances in enhancing the effects of RT have been the primary focus of research in radiation oncology. To avoid the usage of high radiation doses, treatment modalities such as high-intensity focused ultrasound can be implemented to reduce the radiation doses required to destroy cancer cells. In the past few years, the use of focused ultrasound (FUS) has demonstrated immense success in a number of applications as it capitalizes on spatial specificity. It allows ultrasound energy to be delivered to a targeted focal area without harming the surrounding tissue. FUS combined with RT has specifically demonstrated experimental evidence in its application resulting in enhanced cell death and tumor cure. Ultrasound-stimulated microbubbles have recently proved to be a novel way of enhancing RT as a radioenhancing agent on its own, or as a delivery vector for radiosensitizing agents such as oxygen. In this mini-review article, we discuss the bio-effects of FUS and RT in various preclinical models and highlight the applicability of this combined therapy in clinical settings.

Biomarkers of radioresistance in head and neck squamous cell carcinomas

PURPOSE

Head and neck squamous cell carcinoma (HNSCC) is a major cause of morbidity and mortality. Although HNSCC is mainly caused by tobacco and alcohol consumption, infection by Human Papilloma Virus (HPV) has been also associated with the increasing incidence of oropharyngeal squamous cell carcinomas (OPSCC) during the past decades. HPV-positive HNSCC is characterized by a higher radiosensitivity compared to HPV-negative tumor. While several clinical trials are evaluating de-escaladed radiation doses strategies in HPV-positive HNSCC, molecular mechanisms associated with relative radioresistance in HPV-negative HNSCC are still broadly unknown. Our goal was to review recently proposed biomarkers of radioresistance in this setting, which may be useful for stratifying tumor's patient according to predicted level of radioresistance.

CONCLUSIONS

most of biomarkers of radioresistance in HPV-negative HNSCC are identified using a hypothesis-driven approach, based on molecular mechanisms known to play a key role during carcinogenesis, compared to an unsupervised data-driven approach regardless the biological rational. DNA repair and hypoxia are the two most widely investigated biological and targetable pathways related to radioresistance in HNSCC. The better understanding of molecular mechanisms and biomarkers of radioresistance in HPV-negative HNSCC could help for the development of radiosensitization strategies, based on targetable biomarkers, in radioresistant tumors as well as de-escalation radiation dose strategies, based on biological level of radioresistance, in radiosensitive tumors.

Bioinspired nanovehicle of furoxans-oxaliplatin improves tumoral distribution for chemo-radiotherapy

The spatiotemporal distribution of therapeutic agents in tumors remains an essential challenge of radiation-mediated therapy. Herein, we rationally designed a macrophage microvesicle-inspired nanovehicle of nitric oxide donor-oxaliplatin (FO) conjugate (M-PFO), aiming to promote intratumor permeation and distribution profiles for chemo-radiotherapy. FO was responsively released from M-PFO in intracellular acidic environments, and then be activated by glutathione (GSH) into active oxaliplatin and NO molecules in a programmed manner. M-PFO exhibited notable accumulation, permeation and cancer cell accessibility in tumor tissues. Upon radiation, the reactive peroxynitrite species (ONOO^-) were largely produced, which could diffuse into regions over 400 μm away from the tumor vessels and be detectable after 24 h of radiation, thereby exhibiting superior efficacy in improving the spatiotemporal distribution in tumors versus common reactive oxygen species (ROS). Moreover, M-PFO mediated chemo-radiotherapy caused notable inhibition of tumor growth, with an 89.45% inhibition in HT-29 tumor models and a 92.69% suppression in CT-26 tumor models. Therefore, this bioinspired design provides an encouraging platform to improve intratumor spatiotemporal distribution to synergize chemo-radiotherapy.

Lacticaseibacillus casei ATCC334 Ameliorates Radiation-Induced Intestinal Injury in Rats by Targeting Microbes and Metabolites

SCOPE

Gastrointestinal side effects are frequently observed in patients receiving medical radiation therapy. As Lacticaseibacillus casei ATCC334 potentially affects microbial ecosystem, the study hypothesizes that it may improve radiation-induced intestinal injury in rats by modulating the "gut microbiota-metabolite-barrier axis."

METHODS AND RESULTS

Rats are fed one of three or no doses of L. casei ATCC334 for 7 days and then expose to a single dose of 9 Gy X-ray total abdominal irradiation. Supplementation with L. casei ATCC334 promote the proliferation of intestinal stem cells (ISCs), increase the expression of tight junction proteins, reduce intestinal permeability, and protect intestinal barrier integrity. Moreover, 16S rRNA sequencing show that medium and high doses of L. casei ATCC334 inhibit the growth of Escherichia/Shigella and favor Akkermansia proliferation. L. casei ATCC334 intervention reprogram the metabolic profile and inhibit putrescine production but promote alpha-linolenic acid (ALA) production. Notably, a decrease in putrescine and an increase in ALA are significantly correlated with the proliferation of ISCs and enhanced intestinal barrier function following L. casei ATCC334 intervention.

CONCLUSION

These results highlight that medium and high doses of L. casei ATCC334 alleviate radiation-induced intestinal damage by enhancing the mucosal barrier and remodeling the gut microbiota structure and metabolic activity.

Ginsenoside Rg3 enhances the radiosensitivity of lung cancer A549 and H1299 cells via the PI3K/AKT signaling pathway

Lung cancer is one of the most common cancers and the leading cause of cancer-related deaths in the world. Radiation is widely used for the treatment of lung cancer. However, radioresistance and toxicity limit its effectiveness. Ginsenoside Rg3 (Rg3) is a positive monomer extracted from ginseng and has been shown to the anti-cancer ability on many tumors. The aim of the present study was to ascertain whether Rg3 is able to enhance the radiosensitivity of lung cancer cells and investigate the underlying mechanisms. The effect of Rg3 on cell proliferation was examined by Cell Counting Kit-8 (CCK-8) and radiosensitivity was measured by colony formation assay. Flow cytometry, transwell, and wound healing assay were used to determine apoptosis, cell cycle, and metastasis. Western blot was used to detect the main protein levels of the PI3K/AKT signaling pathway. We found that Rg3 inhibited cell proliferation, promoted apoptosis, and suppressed migration and invasion in radio-induced lung cancer cells. In addition, Rg3 increased the proportion of G2/M phase cells and inhibited the formation of cell colonies. Moreover, Rg3 decreased the expression levels of PI3K, p-AKT, and PDK1 in radio-induced cells. These findings indicate that Rg3 may be able to enhance the radiosensitivity in lung cancer cells by the PI3K/AKT signaling pathway. These results demonstrate the therapeutic potential of Rg3 as a radiosensitizer for lung cancer.

Nanotechnology meets glioblastoma multiforme: Emerging therapeutic strategies

Glioblastoma multiforme (GBM) represents the most common and fatal form of primary invasive brain tumors as it affects a great number of patients each year and has a median overall survival of approximately 14.6 months after diagnosis. Despite intensive treatment, almost all patients with GBM experience recurrence, and their 5-year survival rate is approximately 5%. At present, the main clinical treatment strategy includes surgical resection, radiotherapy, and chemotherapy. However, tumor heterogeneity, blood-brain barrier, glioma stem cells, and DNA damage repair mechanisms hinder efficient GBM treatment. The emergence of nanometer-scale diagnostic and therapeutic approaches in cancer medicine due to the establishment of nanotechnology provides novel and promising tools that will allow us to overcome these difficulties. This review summarizes the application and recent progress in nanotechnology-based monotherapies (e.g., chemotherapy) and combination cancer treatment strategies (chemotherapy-based combined cancer therapy) for GBM and describes the synergistic enhancement between these combination therapies as well as the current standard therapy for brain cancer and its deficiencies. These combination therapies that can reduce individual drug-related toxicities and significantly enhance therapeutic efficiency have recently undergone rapid development. The mechanisms underlying these different nanotechnology-based therapies as well as the application of nanotechnology in GBM (e.g., in photodynamic therapy and chemodynamic therapy) have been systematically summarized here in an attempt to review recent developments and to identify promising directions for future research. This review provides novel and clinically significant insights and directions for the treatment of GBM, which is of great clinical importance. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Diagnostic Tools > In Vivo Nanodiagnostics and Imaging.

Gadolinium-Bisphosphonate Nanoparticle-Based Low-Dose Radioimmunotherapy for Osteosarcoma

Osteosarcoma is a malignant osteogenic tumor with a high metastatic rate commonly occurring in adolescents. Although radiotherapy is applied to treat unresectable osteosarcoma with radiation resistance, a high dose of radiotherapy is required, which may weaken the immune microenvironment. Therefore, there is an urgent need to develop novel agents to maximize the radiotherapeutic effects by eliciting immune activation effects. In this study, we synthesized therapeutic gadolinium-based metal-bisphosphonate nanoparticles (NPs) for osteosarcoma treatment that can be combined with radiotherapy. The gadolinium ion (Gd) was chelated with zoledronic acid (Zol), a commonly used drug to prevent/treat osteoporosis or bone metastases from advanced cancers, and stabilized by ovalbumin (OVA) to produce OVA-GdZol NPs. OVA-GdZol NPs were internalized into K7M2 osteosarcoma cells, showing a high sensitization effect under X-ray irradiation. Cell pretreatment of OVA-GdZol NPs significantly enhanced the radiation therapeutic effect in vitro by reducing the cell colonies and increased the signal of γH2AX-positive cells. More importantly, OVA-GdZol NPs promoted the maturation of bone marrow-derived dendritic cells (BMDCs) and M1 polarization of macrophages. The inhibitory effect on K7M2 osteosarcoma of OVA-GdZol NPs and X-ray radiation was evident, indicated by a significantly reduced tumor volume, high survival rate, and decreased lung metastasis. Meanwhile, both innate and adaptive immune systems were activated to exert a strong antitumor effect. The above results highly suggest that OVA-GdZol NPs serve as both radiosensitizers and immune adjuvants, suitable for the sequential combination of vaccination and radiotherapy.

Combined Treatment (Ultraviolet-C/Physapruin A) Enhances Antiproliferation and Oxidative-Stress-Associated Mechanism in Oral Cancer Cells

Physapruin A (PHA), a Physalis peruviana-derived withanolide, exhibits antiproliferation activity against oral and breast cancer cells. However, its potential antitumor effects in combined treatments remain unclear. This investigation focused on evaluating the impact of the combined treatment of ultraviolet-C with PHA (UVC/PHA) on the proliferation of oral cancer cells. The UVC-caused antiproliferation was enhanced by combination with PHA in oral cancer (Ca9-22 and CAL 27) but not normal cells (SG), as evidenced by ATP detection, compared with UVC or PHA alone. UVC/PHA showed a greater extent of subG1 increase, G2/M arrest, annexin-V-assessed apoptosis, caspase 3/7 activation, and reactive oxygen species (ROS) in the UVC or PHA treatment of oral cancer compared to normal cells. Moreover, the mitochondrial functions, such as mitochondrial superoxide bursts and mitochondrial membrane potential destruction, of oral cancer cells were also enhanced by UVC/PHA compared to UVC or PHA alone. These oxidative stresses triggered γH2AX and 8-hydroxyl-2'-deoxyguanosine-assessed DNA damage to a greater extent under UVC/PHA treatment than under UVC or PHA treatment alone. The ROS inhibitor N-acetylcysteine reversed all these UVC/PHA-promoted changes. In conclusion, UVC/PHA is a promising strategy for decreasing the proliferation of oral cancer cells but shows no inhibitory effect on normal cells.

An overview of the intracellular localization of high-Z nanoradiosensitizers

Radiation therapy (RT) is a method commonly used for cancer treatment worldwide. Commonly, RT utilizes two routes for combating cancers: 1) high-energy radiation to generate toxic reactive oxygen species (ROS) (through the dissociation of water molecules) for damaging the deoxyribonucleic acid (DNA) inside the nucleus 2) direct degradation of the DNA. However, cancer cells have mechanisms to survive under intense RT, which can considerably decrease its therapeutic efficacy. Excessive radiation energy damages healthy tissues, and hence, low doses are applied for cancer treatment. Additionally, different radiosensitizers were used to sensitize cancer cells towards RT through individual mechanisms. Following this route, nanoparticle-based radiosensitizers (herein called nanoradiosensitizers) have recently gained attention owing to their ability to produce massive electrons which leads to the production of a huge amount of ROS. The success of the nanoradiosensitizer effect is closely correlated to its interaction with cells and its localization within the cells. In other words, tumor treatment is affected from the chain of events which is started from cell-nanoparticle interaction followed by the nanoparticles direction and homing inside the cell. Therefore, passive or active targeting of the nanoradiosensitizers in the subcellular level and the cell-nano interaction would determine the efficacy of the radiation therapy. The importance of the nanoradiosensitizer's targeting is increased while the organelles beyond nucleus are recently recognized as the mediators of the cancer cell death or resistance under RT. In this review, the principals of cell-nanomaterial interactions and which dominate nanoradiosensitizer efficiency in cancer therapy, are thoroughly discussed.

CircRNAs in Tumor Radioresistance

Circular RNAs (circRNAs) are endogenous, non-coding RNAs, which are derived from host genes that are present in several species and can be involved in the progression of various diseases. circRNAs’ leading role is to act as RNA sponges. In recent years, the other roles of circRNAs have been discovered, such as regulating transcription and translation, regulating host genes, and even being translated into proteins. As some tumor cells are no longer radiosensitive, tumor radioresistance has since become a challenge in treating tumors. In recent years, circRNAs are differentially expressed in tumor cells and can be used as biological markers of tumors. In addition, circRNAs can regulate the radiosensitivity of tumors. Here, we list the mechanisms of circRNAs in glioma, nasopharyngeal carcinoma, and non-small cell lung cancer; further, these studies also provide new ideas for the purposes of eliminating radioresistance in tumors.

Ultrasmall zirconium carbide nanodots for synergistic photothermal-radiotherapy of glioma

Glioma is characterized by highly invasive, progressive, and lethal features. In addition, conventional treatments have been poorly effective in treating glioma. To overcome this challenge, synergistic therapies combining radiotherapy (RT) with photothermal therapy (PTT) have been proposed and extensively explored as a highly feasible cancer treatment strategy. Herein, ultrasmall zirconium carbide (ZrC) nanodots were successfully synthesized with high near-infrared absorption and strong photon attenuation for synergistic PTT-RT of glioma. ZrC-PVP nanodots with an average size of approximately 4.36 nm were prepared by the liquid exfoliation method and modified with the surfactant polyvinylpyrrolidone (PVP), with a satisfactory absorption and photothermal conversion efficiency (53.4%) in the near-infrared region. Furthermore, ZrC-PVP nanodots can also act as radiosensitizers to kill residual tumor cells after mild PTT due to their excellent photon attenuating ability, thus achieving a significant synergistic therapeutic effect by combining RT and PTT. Most importantly, both in vitro and in vivo experimental results further validate the high biosafety of ZrC-PVP NDs at the injected dose. This work systematically evaluates the feasibility of ZrC-PVP NDs for glioma treatment and provides evidence of the application of zirconium-based nanomaterials in photothermal radiotherapy.

AGuIX nanoparticles enhance ionizing radiation-induced ferroptosis on tumor cells by targeting the NRF2-GPX4 signaling pathway

In the frame of radiotherapy treatment of cancer, radioresistance remains a major issue that still needs solutions to be overcome. To effectively improve the radiosensitivity of tumors and reduce the damage of radiation to neighboring normal tissues, radiosensitizers have been given increasing attention in recent years. As nanoparticles based on the metal element gadolinium, AGuIX nanoparticles have been shown to increase the radiosensitivity of cancers. Although it is a rare nanomaterial that has entered preclinical trials, the unclear biological mechanism hinders its further clinical application. In this study, we demonstrated the effectiveness of AGuIX nanoparticles in the radiosensitization of triple-negative breast cancer. We found that AGuIX nanoparticles increased the level of DNA damage by compromising the homologous recombination repair pathway instead of the non-homologous end joining pathway. Moreover, the results showed that AGuIX nanoparticles induced apoptosis, but the degree of apoptosis ability was very low, which cannot fully explain their strong radiosensitizing effect. Ferroptosis, the other mode of cell death, was also discovered to play a significant role in radiation sensitization, and AGuIX nanoparticles may regulate the anti-ferroptosis system by inhibiting the NRF2-GSH-GPX4 signaling pathway.

Novel Implications of Nanoparticle-Enhanced Radiotherapy and Brachytherapy: Z-Effect and Tumor Hypoxia

Radiotherapy and internal radioisotope therapy (brachytherapy) induce tumor cell death through different molecular signaling pathways. However, these therapies in cancer patients are constrained by dose-related adverse effects and local discomfort due to the prolonged exposure to the surrounding tissues. Technological advancements in nanotechnology have resulted in synthesis of high atomic elements such as nanomaterials, which can be used as radiosensitizers due to their photoelectric characteristics. The aim of this review is to elucidate the effects of novel nanomaterials in the field of radiation oncology to ameliorate dose-related toxicity through the application of ideal nanoparticle-based radiosensitizers such as Au (gold), Bi (bismuth), and Lu (Lutetium-177) for enhancing cytotoxic effects of radiotherapy via the high-Z effect. In addition, we discuss the role of nanoparticle-enhanced radiotherapy in alleviating tumor hypoxia through the nanodelivery of genes/drugs and other functional anticancer molecules. The implications of engineered nanoparticles in preclinical and clinical studies still need to be studied in order to explore potential mechanisms for radiosensitization by minimizing tumor hypoxia, operational/logistic complications and by overcoming tumor heterogeneity in radiotherapy/brachytherapy.

Fluorinated Hyaluronic Acid Encapsulated Perfluorocarbon Nanoparticles as Tumor-Targeted Oxygen Carriers to Enhance Radiotherapy

The efficacy of radiotherapy is significantly constricted by tumor hypoxia. To overcome this obstacle, one promising approach is to use the perfluorocarbon-based O₂ carriers combined with hyperoxic respiration to relieve tumor hypoxia. However, this passively transported oxygen carrier during hyperoxic respiration is prone to cause systemic oxidative stress and toxicity, which further limits its clinical application. Herein, we fabricate O₂@PFC@FHA NPs for safe and specific oxygen delivery into tumors by using the fluorinated hyaluronic acid to encapsulate O₂-saturated perfluorocarbon. Due to the interaction between HA and CD44 receptors, more FHA@PFC NPs accumulated in the tumor and the O₂@PFC@FHA NPs significantly relieved tumor hypoxia. Notably, RT plus O₂@PFC@FHA NPs resulted in almost threefold therapeutic improvement compared with RT without obvious systemic toxicity. Therefore, the O₂@FHA@PFC NPs may have great potential to enhance the therapeutic efficacy of radiotherapy in the clinic.

Natural products as chemo-radiation therapy sensitizers in cancers

Cancer is a devastating disease and is the second leading cause of death worldwide. Surgery, chemotherapy (CT), and/or radiation therapy (RT) are the treatment of choice for most advanced tumors. Unfortunately, treatment failure due to intrinsic and acquired resistance to the current CT and RT is a significant challenge associated with poor patient prognosis. There is an urgent need to develop and identify agents that can sensitize tumor cells to chemo-radiation therapy (CRT) with minimal cytotoxicity to the healthy tissues. While many recent studies have identified the underlying molecular mechanisms and therapeutic targets for CRT failure, using small molecule inhibitors to chemo/radio sensitize tumors is associated with high toxicity and increased morbidity. Natural products have long been used as chemopreventive agents in many cancers. Combining many of these compounds with the standard chemotherapeutic agents or with RT has shown synergistic effects on cancer cell death and overall improvement in patient survival. Based on the available data, there is strong evidence that natural products have a robust therapeutic potential along with CRT and their well-known chemopreventive effects in many solid tumors. This review article reports updated literature on different natural products used as CT or RT sensitizers in many solid tumors. This is the first review discussing CT and RT sensitizers together in cancer.

Integrating the microneedles with carboplatin to facilitate the therapeutic effect of radiotherapy for skin cancers

In most skin cancer patients, excisional surgery is required to remove tumorous tissue. However, the risk of locoregional recurrence after surgery alone is relatively high, particularly for a locally advanced stage of melanoma. Therefore, additional adjuvant treatments, such as radiotherapy, can be used after surgery to inhibit recurrent melanoma after surgical removal. To enhance local radiotherapy, we present the combined X-ray radiation and radiosensitizers (carboplatin) through microneedles (MNs) to treat melanoma. The MNs could be beneficial to precisely delivering carboplatin into the sub-epidermal layer of the melanoma region and alleviate patients' fear and discomfort during the drug administration compared to the traditional local injection. The carboplatin was loaded into the tips of dissolving gelatin MNs (carboplatin-MNs) through the molding method. The results show gelatin MNs have sufficient mechanical strength and can successfully administer carboplatin into the skin. Both in vitro and in vivo studies suggest that carboplatin can enhance radiotherapy in melanoma treatment. With a combination of radiotherapy and carboplatin, the inhibition effect of carboplatin delivered into the B16F10 murine melanoma model through MNs administration (1.2 mg/kg) is equivalent to that through an intravenous route (5 mg/kg). The results demonstrate a promise of combined carboplatin and X-ray radiation treatment in treating melanoma by MNs administration.

Dose-enhancement of MCF 7 cell line radiotherapy using silica-iron oxide nanocomposite

Cancer radiotherapy is one of the most effective regimens of cancer treatments, but cancer cell radioresistance remains a concern. Radiosensitizers can selectively improve the efficacy of radiotherapy and reduce inherent damage. The purpose of this work is to evaluate the effect of silica-coated iron oxide magnetic nanoparticles (SIONPs) as a radiosensitizer and compare their therapeutic effect with that of Iron oxide magnetic nanoparticles (IONPs). IONPs and SIONPs were characterized using several physical techniques such as a transmission electron microscope (TEM) and Vibrating sample magnetometer (VSM). MTT and DNA double-strand breaks (Comet) assays have been used to detect the cytotoxicity, cell viability, and DNA damage of MCF-7 cells, which were treated with different concentrations of prepared nanoparticles and exposed to an X-ray beam. In this study, an efficient radiosensitizer, SIONPs, was successfully prepared and characterized. With 0.5 Gy dose, dose enhancement factor (DEF) values of cells treated with 5 and 10 μg/ml of IONPs were 1 and 1.09, respectively, while those treated with SIONPs at these concentrations had DEF of 1.21 and 1.32, respectively. Results demonstrated that SIONPs provide a potential for improving the radiosensitivity of breast cancer.