Radiation dose rate affects the radiosensitization of MCF-7 and HeLa cell lines to X-rays induced by dextran-coated iron oxide nanoparticles

Targeting S6K/NFκB/SQSTM1/Polθ signaling to suppress radiation resistance in prostate cancer

In this study we have identified POLθ-S6K-p62 as a novel druggable regulator of radiation response in prostate cancer. Despite significant advances in delivery, radiotherapy continues to negatively affect treatment outcomes and quality of life due to resistance and late toxic effects to the surrounding normal tissues such as bladder and rectum. It is essential to develop new and effective strategies to achieve better control of tumor. We found that ribosomal protein S6K (RPS6KB1) is elevated in human prostate tumors, and contributes to resistance to radiation. As a downstream effector of mTOR signaling, S6K is known to be involved in growth regulation. However, the impact of S6K signaling on radiation response has not been fully explored. Here we show that loss of S6K led to formation of smaller tumors with less metastatic ability in mice. Mechanistically we found that S6K depletion reduced NFκB and SQSTM1 (p62) reporter activity and DNA polymerase θ (POLθ) that is involved in alternate end-joining repair. We further show that the natural compound berberine interacts with S6K in a in a hitherto unreported novel mode and that pharmacological inhibition of S6K with berberine reduces Polθ and downregulates p62 transcriptional activity via NFκB. Loss of S6K or pre-treatment with berberine improved response to radiation in prostate cancer cells and prevented radiation-mediated resurgence of PSA in animals implanted with prostate cancer cells. Notably, silencing POLQ in S6K overexpressing cells enhanced response to radiation suggesting S6K sensitizes prostate cancer cells to radiation via POLQ. Additionally, inhibition of autophagy with CQ potentiated growth inhibition induced by berberine plus radiation. These observations suggest that pharmacological inhibition of S6K with berberine not only downregulates NFκB/p62 signaling to disrupt autophagic flux but also decreases Polθ. Therefore, combination treatment with radiation and berberine inhibits autophagy and alternate end-joining DNA repair, two processes associated with radioresistance leading to increased radiation sensitivity.

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

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

Superparamagnetic iron oxide nanoparticles induce persistent large foci of DNA damage in human melanoma cells post-irradiation

The synergy of superparamagnetic iron oxide nanoparticles (SPIONs) and ionizing radiation (IR), attributed to reactive oxygen species (ROS) and DNA double-strand breaks (DSBs) increase, was widely investigated in different cancers, but scarcely in melanoma. Herein, SPIONs were evaluated as radiosensitizers in A-375 human melanoma cells. Moreover, the effect of the combined treatment of SPIONs and gamma irradiation (SPIONs-IR) was assessed at the DNA level, where DSBs induction and their repair capacity were studied. SPIONs were synthesized, stabilized by poly(ethylene glycol) methyl ether and physicochemically characterized by high resolution-transmission electron microscopy (HR-TEM), X-ray diffraction and magnetometry and dynamic light scattering. The obtained nanoparticles showing superparamagnetic behavior and low dispersion in shape and sizes were tested in A-375 cells. The intracellular internalization of SPIONs was verified by HR-TEM and quantified by inductively coupled plasma atomic emission spectroscopy. Cells treated with SPIONs exhibited high ROS levels without associated cytotoxicity. Next, a significant radiosensitization in SPIONs-IR vs. control (IR) cells was demonstrated at 1 Gy of gamma radiation. Furthermore, a decreased DSBs repair capacity in SPIONs-IR vs. IR-treated cells was evidenced by the size increase of persistent phosphorylated H2AX foci at 24 h post-irradiation. In conclusion, these nanoparticles show the potential to radiosensitize melanoma cells by the induction of unrepairable DNA damage.

Nanoscopic biodosimetry using plasmid DNA in radiotherapy with metallic nanoparticles

Nanoscopic lesions (complex damages), are the most lethal lesions for the cells. As nanoparticles have become increasingly popular in radiation therapy and the importance of analyzing nanoscopic dose enhancement has increased, a reliable tool for nanodosimetry has become indispensable. In this regard, the DNA plasmid is a widely used tool as a nanodosimetry probe in radiobiology and nano-radiosensitization studies. This approach is helpful for unraveling the radiosensitization role of nanoparticles in terms of physical and physicochemical effects and for quantifying radiation-induced biological damage. This review discusses the potential of using plasmid DNA assays for assessing the relative effects of nano-radiosensitizers, which can provide a theoretical basis for the development of nanoscopic biodosimetry and nanoparticle-based radiotherapy.

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.

Matrices and Affinity Ligands for Antibody Purification and Corresponding Applications in Radiotherapy

Antibodies have become an important class of biological products in cancer treatments such as radiotherapy. The growing therapeutic applications have driven a demand for high-purity antibodies. Affinity chromatography with a high affinity and specificity has always been utilized to separate antibodies from complex mixtures. Quality chromatographic components (matrices and affinity ligands) have either been found or generated to increase the purity and yield of antibodies. More importantly, some matrices (mainly particles) and affinity ligands (including design protocols) for antibody purification can act as radiosensitizers or carriers for therapeutic radionuclides (or for radiosensitizers) either directly or indirectly to improve the therapeutic efficiency of radiotherapy. This paper provides a brief overview on the matrices and ligands used in affinity chromatography that are involved in antibody purification and emphasizes their applications in radiotherapy to enrich potential approaches for improving the efficacy of radiotherapy.

Radiosensitization effects by bismuth oxide nanorods of different sizes in megavoltage external beam radiotherapy

Background

Nanotechnology application has successfully reached numerous scientific breakthroughs including in radiotherapy. However, the clinical application of nanoparticles requires more diligent research primarily on the crucial parameters such as nanoparticle sizes. This study is aimed to investigate the influence of bismuth oxide nanorod (Bi₂O₃-NR) sizes on radiosensitization effects on MCF-7 and HeLa cell lines for megavoltage photon and electron beam radiotherapy.

Materials and methods

MCF-7 and HeLa cells were treated with and without 0.5 μMol/L of Bi₂O₃-NR of varying sizes (60, 70, 80, and 90 nm). The samples, including the control groups, were exposed to different radiation doses (0-10 Gy), using photon (6 MV and 10 MV), and electron beam (6 MeV and 12 MeV) radiotherapy. Clonogenic assay was performed, and sensitization enhancement ratio (SER) was determined from linear quadratic based cell survival curves.

Results

The results depicted that 60 nm Bi₂O₃-NR yields the most excellent SER followed by 70 nm Bi₂O₃-NR. Meanwhile, the 80 and 90 nm Bi₂O₃-NR showed an insignificant difference between treated and untreated cell groups. This study also found that MCF-7 was subjected to more cell death compared to HeLa.

Conclusion

60 nm Bi₂O₃-NR was the optimal Bi₂O₃-NR size to induce radiosensitization effects for megavoltage external beam radiotherapy. The SER in photon beam radiotherapy marked the highest compared to electron beam radiotherapy due to decreased primary radiation energy from multiple radiation interaction and higher Compton scattering.

Impact of superparamagnetic iron oxide nanoparticles on in vitro and in vivo radiosensitisation of cancer cells

PURPOSE

The recent implementation of MR-Linacs has highlighted theranostic opportunities of contrast agents in both imaging and radiotherapy. There is a lack of data exploring the potential of superparamagnetic iron oxide nanoparticles (SPIONs) as radiosensitisers. Through preclinical 225 kVp exposures, this study aimed to characterise the uptake and radiobiological effects of SPIONs in tumour cell models in vitro and to provide proof-of-principle application in a xenograft tumour model.

METHODS

SPIONs were also characterised to determine their hydrodynamic radius using dynamic light scattering and uptake was measured using ICP-MS in 6 cancer cell lines; H460, MiaPaCa2, DU145, MCF7, U87 and HEPG2. The impact of SPIONs on radiobiological response was determined by measuring DNA damage using 53BP1 immunofluorescence and cell survival. Sensitisation Enhancement Ratios (SERs) were compared with the predicted Dose Enhancement Ratios (DEFs) based on physical absorption estimations. In vivo efficacy was demonstrated using a subcutaneous H460 xenograft tumour model in SCID mice by following intra-tumoural injection of SPIONs.

RESULTS

The hydrodynamic radius was found to be between 110 and 130 nm, with evidence of being monodisperse in nature. SPIONs significantly increased DNA damage in all cell lines with the exception of U87 cells at a dose of 1 Gy, 1 h post-irradiation. Levels of DNA damage correlated with the cell survival, in which all cell lines except U87 cells showed an increased sensitivity (P < 0.05) in the linear quadratic curve fit for 1 h exposure to 23.5 μg/ml SPIONs. There was also a 30.1% increase in the number of DNA damage foci found for HEPG2 cells at 2 Gy. No strong correlation was found between SPION uptake and DNA damage at any dose, yet the biological consequences of SPIONs on radiosensitisation were found to be much greater, with SERs up to 1.28 ± 0.03, compared with predicted physical dose enhancement levels of 1.0001. In vivo, intra-tumoural injection of SPIONs combined with radiation showed significant tumour growth delay compared to animals treated with radiation or SPIONs alone (P < 0.05).

CONCLUSIONS

SPIONs showed radiosensitising effects in 5 out of 6 cancer cell lines. No correlation was found between the cell-specific uptake of SPIONs into the cells and DNA damage levels. The in vivo study found a significant decrease in the tumour growth rate.

Radiosensitizing effects of citrate-coated cobalt and nickel ferrite nanoparticles on breast cancer cells

Aim: Evaluation of the biocompatibility and radiosensitizer potential of citrate-coated cobalt (cit-CF) and nickel (cit-NF) ferrite nanoparticles (NPs). Materials & methods: Normal fibroblast and breast cancer cells were treated with different concentrations of citrate-coated ferrite NPs (cit-NPs) and irradiated with a cobalt-60 source at doses of 1 and 3 Gy. After 24 h, cell metabolism, morphology alterations and nanoparticle uptake were evaluated. Results: Cit-CF and cit-NF NPs showed no toxicity to normal cells up to 250 and 100 μg.ml^-1, respectively. Combination of cit-NP and ionizing radiation resulted in up to fivefold increase in the radiation therapeutic efficacy against breast cancer cells. Conclusion: Cit-CF and cit-NF NPs are suitable candidates for application as breast cancer cell radiosensitizers.

Radiosensitization by Gold Nanoparticles: Impact of the Size, Dose Rate, and Photon Energy

Gold nanoparticles (GNPs) emerged as promising antitumor radiosensitizers. However, the complex dependence of GNPs radiosensitization on the irradiation conditions remains unclear. In the present study, we investigated the impacts of the dose rate and photon energy on damage of the pBR322 plasmid DNA exposed to X-rays in the presence of 12 nm, 15 nm, 21 nm, and 26 nm GNPs. The greatest radiosensitization was observed for 26 nm GNPs. The sensitizer enhancement ratio (SER) 2.74 ± 0.61 was observed at 200 kVp with 2.4 mg/mL GNPs. Reduction of X-ray tube voltage to 150 and 100 kVp led to a smaller effect. We demonstrate for the first time that the change of the dose rate differentially influences on radiosensitization by GNPs of various sizes. For 12 nm, an increase in the dose rate from 0.2 to 2.1 Gy/min led to a ~1.13-fold increase in radiosensitization. No differences in the effect of 15 nm GNPs was found within the 0.85–2.1 Gy/min range. For 21 nm and 26 nm GNPs, an enhanced radiosensitization was observed along with the decreased dose rate from 2.1 to 0.2 Gy/min. Thus, GNPs are an effective tool for increasing the efficacy of orthovoltage X-ray exposure. However, careful selection of irradiation conditions is a key prerequisite for optimal radiosensitization efficacy.

Investigating the effect of radiosensitizer for Ursolic Acid and Kamolonol Acetate ‌ on HCT-116 cell line

PURPOSE

The aim of this study was evaluating the cytotoxic and radiosensitizing effects of Ursolic Acid (UA) and Kamolonol Acetate (KA) on HCT116 cell line and finally investigating the functional role of NF-κB and CCND1 genes in the radiosensitizing activity of UA and KA.

MATERIALS AND METHOD

The cytotoxic effects of UA and KA by MTT assay was evaluated on HCT-116. Clonogenic assay was performed to investigate of radiosensitizing effects of UA and KA on HCT116. To assessment the expression levels of NF-κB and CCND1 genes, real-time PCR method was used.

RESULTS

The results of MTT assay revealed that UA and KA have cytotoxic effects on HCT116 cell line. According to clonogenic assay, survival fraction of treated cells with UA and KA has been decreased compared to the survival fraction of untreated cells. UA and KA lead to the decrease in the expression level of NF-κB. Synergistic effect of radiosensitizing agents with radiation was only approved for UA and 2 Gy of radiation.

CONCLUSION

Based on our study, UA and KA have cytotoxic effects on HCT116 cell line. Furthermore, UA may lead to radiosensitization of human colorectal tumor cells by NF-κB1 and CCND1signaling pathways.

Potential of MRI in Radiotherapy Mediated by Small Conjugates and Nanosystems

Radiation therapy has made tremendous progress in oncology over the last decades due to advances in engineering and physical sciences in combination with better biochemical, genetic and molecular understanding of this disease. Local delivery of optimal radiation dose to a tumor, while sparing healthy surrounding tissues, remains a great challenge, especially in the proximity of vital organs. Therefore, imaging plays a key role in tumor staging, accurate target volume delineation, assessment of individual radiation resistance and even personalized dose prescription. From this point of view, radiotherapy might be one of the few therapeutic modalities that relies entirely on high-resolution imaging. Magnetic resonance imaging (MRI) with its superior soft-tissue resolution is already used in radiotherapy treatment planning complementing conventional computed tomography (CT). Development of systems integrating MRI and linear accelerators opens possibilities for simultaneous imaging and therapy, which in turn, generates the need for imaging probes with therapeutic components. In this review, we discuss the role of MRI in both external and internal radiotherapy focusing on the most important examples of contrast agents with combined therapeutic potential.

Investigating the Cytotoxicity of Folate-Conjugated Bismuth Oxide Nanoparticles on KB and A549 Cell Lines

Purpose: Lately, bismuth-based nanomaterials have been widely utilized in medical researches such as imaging, drug delivery and radio-sensitization. Despite their advantages, bismuth-based compounds have shown toxic effects in humans. There are few studies on cytotoxicity effects of bismuth oxide (Bi2O3) nanoparticles (NPs) in-vitro. In this study, we aimed to investigate cytotoxicity of bare and also folate and 5-aminolevulinic acid (5-ALA)-conjugated Bi2O3 NPs on nasopharyngeal carcinoma (KB) and lung cancer (A549) cell lines.

Methods: B_i2O₃ NPs were synthesized and conjugated with folate and 5-ALA. KB and A549 cells were cultured and incubated with 10, 20, 50 and 100 μg/ml concentrations of bare and folate-5-ALA-conjugated NPs. The survival rates were obtained after 2 and 24 hours incubation of the cells with NPs using MTT assay. Also, apoptosis and ROS generation induced by the NPs in the treated cells were obtained using Caspases-3 activity assay and flow cytometry analysis, respectively.

Results: B_i2O₃ NPs were successfully synthesized with average size of 19.2 ± 6.5 nm, then conjugated with 5-ALA and folate. Either naked or folate-conjugated NPs were easily taken up by the cells in a concentration-dependent manner and showed cytotoxic effects. The significant cell death was noted at the concentrations more than 50 μg/ml for both compounds.

Conclusion: Results indicated low cytotoxicity of the prepared NPs at lower incubation periods, which is very important for their further applications. However, 24 hours incubation of the cells with both forms of NPs caused more cell killing and the cytotoxicity increased with increasing concentrations of the NPs.

In vitro outlook of gold nanoparticles in photo-thermal therapy: a literature review

Hyperthermia is an anti-cancer treatment in which the temperature of the malignant tumor is increased more than other adjacent normal tissues. Microwave, ultrasound, laser, and radiofrequency sources have been used for hyperthermia of cancerous tissues. In the past decade, near-infrared (NIR) laser for cancer therapy, known as photo-thermal therapy (PTT), was expanded in which the photo-sensitizer agent converts the light photon energy to heat. The heat following PTT can destroy cancer cells. There are some photo-sensitizer agents which have been used for PTT; however, owing to recent advances in nanotechnology, noble metal nanoparticles like gold (Au) nanoparticles (GNPs) have been used successfully in PTT. GNPs have some desirable specifications, including simple and controlled synthesis, small size, high level of biocompatibility, and surface plasmon resonance (SPR). The SPR effect of the GNPs increases the radiative properties like absorption and scattering; therefore, they can be used in PTT. In this article, we reviewed recent in vitro studies of PTT using GNPs in literature. At first, we focus on the physical properties of GNPs, their interaction with infrared radiation, and physical parameters governing the interaction of infrared radiation with the GNPs. Then, we review the passive and active targeting of GNPs using the different coating to induce the thermal damage in cancer cells using low-level laser PPT. The GNPs' cellular internalization into cancer cells is a challenge which is consequently considered. In this review, we also summarize the results of synergistic cancer therapy studies on the combination of radiation therapy as a routine cancer treatment and PTT: in which significant improvement occurs in treatment efficacy.