Radiosensitization effect of radiofrequency hyperthermia in the presence of PEGylated-gold nanoparticles on the MCF-7 breast cancer cells under 6 MeV electron irradiation.

Purpose: The purpose of the study was to investigate the radiosensitization effect of radiofrequency (RF) hyperthermia in combination with PEGylated gold nanoparticles (PEG-GNPs) on MCF-7 breast cancer cells under electron beam radiotherapy (EBRT) based on the clonogenic assay. Materials and Methods: The cell death of MCF-7 breast cancer cells treated with 13.56 MHz capacitive RF hyperthermia (power: 150W) for 2, 5, 10, and 15 min combined with 6 MeV EBRT, with a dose of 2 Gy, was evaluated in the presence of 20 nm PEG-GNPs with a low nontoxic concentration (20 mg/l). All the treatment groups were incubated for 14 days. Thereafter, survival fractions and viability of the cells were calculated and analyzed against the control group. Results: The presence of PEG-GNPs inside the MCF-7 cancer cells during electron irradiation decreased cell survival significantly (16.7%) compared to irradiated cells without GNPs. Applying hyperthermia before electron irradiation with a capacitive RF system decreased cell survival by about 53.7%, while hyperthermia without irradiation did not show any significant effect on cell survival. Combining the hyperthermia with the presence of PEG-GNPs in the cells decreased the cell survival by about 67% at the electron irradiation, showing their additive radiosensitization effect. Conclusion: Low nontoxic concentration of 20 nm PEG-GNPs increases the radiosensitization effect of combining 6 MeV EBRT and RF hyperthermia on MCF-7 cancer cells. Combining hyperthermia with PEG-GNPs in electron radiotherapy could be an appropriate method for enhancing radiotherapy effectiveness on cancerous cells which can be studied on different cells and electron energies in future research.

Effect of 13.56 MHz radiofrequency hyperthermia on mitotic cell cycle arrest in MCF7 breast cancer cell line and suggest a time interval for radiotherapy.

Introduction: After surgery, radiotherapy is the most common technique to treat breast cancer. Over the past decades, the thermal effects of radiofrequency-wave hyperthermia combined with radiotherapy have been used to increase radiosensitivity in cancer treatment. The cells have various radiation and thermal sensitivities at different stages of the mitotic cycle. Furthermore, ionizing radiation and the thermal effect of hyperthermia affect the cells' mitotic cycle and can partly induce cell cycle arrest. However, the time interval between hyperthermia and radiotherapy, as an essential factor influencing hyperthermia effect on cancer cells' cycle arrest, has not been studied before. In this study, we investigated the effect of hyperthermia on the MCF7 cancer cell cycle arrest in mitotic cycles at various selected time intervals after hyperthermia to find and propose appropriate time intervals between hyperthermia and radiotherapy. Method and Materials: In this experimental study, we used the MCF7 breast cancer cell line to investigate the effect of 13.56 MHz hyperthermia (at a temperature of 43°C for a period of 20 min) on their cell cycle arrest. We performed the flowcytometry assay to assess the changes in the mitotic phases of the cell population at different time intervals (1, 6, 24, and 48 h) after hyperthermia. Results: Our flowcytometry results indicated the 24-h time interval has the most significant effect on the cell population at S and G2/M phases. Therefore, the 24-h time interval can be proposed as the most appropriate time after hyperthermia for carrying out combinational radiotherapy procedure. Conclusion: Among various investigated time intervals examined in our research, the 24-h time interval can be proposed as the most appropriate time between hyperthermia and radiotherapy for combinational therapy of breast cancer cells.

Sensitization of glioblastoma cancer cells to radiotherapy and magnetic hyperthermia by targeted temozolomide-loaded magnetite tri-block copolymer nanoparticles as a nanotheranostic agent.

AIMS: Recently, the development of new strategies in the treatment and diagnosis of cancer cells such as thermo-radiation-sensitizer and theranostic agents have received a great deal of attention. In this work, folic acid-conjugated temozolomide-loaded SPION@PEG-PBA-PEG nanoparticles (TMZ-MNP-FA NPs) were proposed for use as magnetic resonance imaging (MRI) contrast agents and to enhance the cytotoxic effects of hyperthermia and radiotherapy. MAIN METHODS: Nanoparticles were synthesized by the Nano-precipitation method and their characteristics were determined by dynamic light scattering (DLS), scanning electron microscopy (SEM) and X-ray powder diffraction (XRD). To evaluate the thermo-radio-sensitization effects of NPs, C6 cells were treated with nanoparticles for 24 h and then exposed to 6-MV X-ray radiation. After radiotherapy, the cells were subjected to an alternating magnetic field (AMF) hyperthermia. The therapeutic potential was assessed using clonogenic assay, ROS generation measurement, flow cytometry assay, and qRT-PCR analysis. Also, the diagnostic properties of the nanoparticles were assessed by MRI. KEY FINDINGS: MRI scanning indicated that nanoparticles accumulated in C6 cells could be tracked by T2-weighted MR imaging. Colony formation assay proved that TMZ-MNP-FA NPs enhanced the anti-proliferation effects of AMF by 1.94-fold compared to AMF alone (P < 0.0001). Moreover, these NPs improved the radiation effects with a dose enhancement factor of 1.65. All results showed that the combination of carrier-based chemotherapy with hyperthermia and radiotherapy caused a higher anticancer efficacy than single- or two-modality treatments. SIGNIFICANCE: The nanoparticles advanced in this study can be proposed as the promising theranostic and thermo-radio-sensitizer platform for the diagnosis and tri-modal synergistic cancer therapy.

Enhancement of Radio-Thermo-Sensitivity of 5-Iodo-2-Deoxyuridine-Loaded Polymeric-Coated Magnetic Nanoparticles Triggers Apoptosis in U87MG Human Glioblastoma Cancer Cell Line.

INTRODUCTION: With an emphasis on the radioresistant nature of glioblastoma cells, the aim of the present study was to evaluate the radio-thermo-sensitizing effects of PCL-PEG-coated Superparamagnetic iron oxide nanoparticles (SPIONs) as a carrier of 5-iodo-2-deoxyuridine (IUdR) in monolayer culture of U87MG human glioma cell line. METHODS: Following monolayer culture of U87MG cells, nanoparticle uptake was assessed using Prussian blue staining and ICP-OES method. The U87MG cells were treated with an appropriate concentration of free IUdR and PCL-PEG-coated SPIONs (MNPs) loaded with IUdR (IUdR/MNPs) for 24 h, subjected to hyperthermia (water bath and alternating magnetic field (AMF)) at 43 °C, and exposed to X-ray (2 Gy, 6 MV). The combined effects of hyperthermia with or without magnetic nanoparticles on radiosensitivity of the U87MG cells were evaluated using colony formation assay (CFA) and Flowcytometry. RESULTS: Prussian blue staining and ICP-OES showed that the nanoparticles were able to enter the cells. The results also indicated that IUdR/MNPs combined with X-ray radiation and hyperthermia significantly decreased the colony formation ability of monolayer cells (1.11, 1.41 fold) and increased the percentage of apoptotic (2.47, 4.1 fold) and necrotic cells (12.28, 29.34 fold), when compared to IUdR combined with X-ray and hyperthermia or IUdR/MNPs + X-ray. MTT results revealed that the presence of IUdR/MNPs significantly increased the toxicity of AMF hyperthermia compared to the water bath method. CONCLUSIONS: Our study showed that SPIONs/PCL-PEG, as a carrier of IUdR, can enhance the cytotoxic effects of radiotherapy and hyperthermia and act as a radio-thermo-sensitizing agent. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12195-021-00675-y.

Combinatorial effects of radiofrequency hyperthermia and radiotherapy in the presence of magneto-plasmonic nanoparticles on MCF-7 breast cancer cells.

Here, the effects of combinatorial cancer therapy including radiotherapy (RT) and radiofrequency (RF) hyperthermia in the presence of gold-coated iron oxide nanoparticles (Au@IONPs), as a thermo-radio-sensitizer, are reported. The level of cell death and the ratio of Bax/Bcl2 genes, involved in the pathway of apoptosis, were measured to evaluate the synergistic effect of Au@IONPs-mediated RF hyperthermia and RT. MCF-7 human breast adenocarcinoma cells were treated with different concentrations of Au@IONPs. After incubation with NPs, the cells were exposed to RF waves (13.56 MHz; 100 W; 15 min). At the same time, thermometry was performed with an infrared (IR) camera. Then, the cells were exposed to 6 MV X-ray at various doses of 2 and 4 Gy. MTT (3-[4,5-dimethylthiazol-2-y1]-2,5-diphenyltetrazolium bromide) assay was performed to evaluate cell viability and quantitative real-time polymerase chain reaction (qRT-PCR) was used to determine the expression ratio of Bax/Bcl2. Cellular uptake of nanoparticles was confirmed qualitatively and quantitatively. The results obtained from MTT assay and qRT-PCR studies showed that NPs and RF hyperthermia had no significant effect when applied separately, while their combination had synergistic effects on cell viability percentage and the level of apoptosis induction. A synergistic effect was also observed when the cancer cells were treated with a combination of NPs, RF hyperthermia, and RT. On the basis of the obtained results, it may be concluded that the use of magneto-plasmonic NPs in the process of hyperthermia and RT of cancer holds a great promise to develop a new combinatorial cancer therapy strategy.

Capacitive hyperthermia as an alternative to brachytherapy in DNA damages of human prostate cancer cell line (DU-145).

PURPOSE: The aim of this study was the evaluation of induced DNA damages of human prostate cancer cells, DU-145, treated with a combination of radiofrequency capacitive hyperthermia (HT) and teletherapy (EBRT) compared to a combination of teletherapy with high-dose rate brachytherapy (BR). MATERIALS AND METHODS: DU-145 cells were cultured as spheroids in 300 micron diameter. Then the following treatments were conducted: (a) EBRT at doses of either 2 Gy or 4 Gy of photon 15 MV, (b) HT for 0, 30, 60, and 90 minutes duration at 43 °C from a 13.56 MHz radiofrequency capacitive heating device (Celsius TCS), (c) BR with Ir-192 seed at doses of either 2 Gy or 5.5 Gy, (d) The mentioned HT followed by EBRT (HT + EBRT) and (e) EBRT followed by BR (EBRT + BR). Alkaline comet assay was performed to measure tail moment. RESULTS: The induced DNA damages of DU-145 cells treated by adding HT to EBRT compared with EBRT alone, showed a significant enhancement; 3.28 and 5.14 times respectively for 30 and 60 minutes HT. By plotting dose-response curves, we could find a range of doses, which create radiobiological iso-effect in HT + EBRT and EBRT + BR treatments. CONCLUSIONS: This study suggests that about DNA damages of DU-145 cells, HT + EBRT could partly be considered as an alternative to EBRT + BR.

Evaluation of combined effect of hyperthermia and ionizing radiation on cytotoxic damages induced by IUdR-loaded PCL-PEG-coated magnetic nanoparticles in spheroid culture of U87MG glioblastoma cell line.

PURPOSE: Glioblastoma multiform (GBM) is the most prevalent and aggressive type of primary brain tumor. None of the current conventional treatment methods has improved treatment considerably. Therefore, in this study the effect of magnetic nanoparticles coated with poly (caprolactone)-poly (ethylene glycol) (PCL-PEG) as a 5-iodo 2'deoxyuridine (IUdR) carrier in the presence of hyperthermia and 6 MV (megavoltage) X-ray radiation, were investigated in a spheroid model of U87MG glioblastoma cell line using colony formation assay. MATERIALS AND METHODS: First, the human glioblastoma cell line U87MG was cultured as a spheroid using the liquid overlay technique. Spheroids on day 10 with 100 mm diameters were treated with 1 µM IUdR or nanoparticles as IUdR carriers for one volume doubling time (VDT) of spheroids (67 h) and hyperthermia at 43 °C for 1 h, and then irradiated with 2 Gy of 6 MV X-ray in different groups. Finally, the effect of treatment on colony-forming ability was obtained by colony formation and alkaline assay. RESULTS: Our results revealed that hyperthermia in combination with radiation could significantly reduce the colony number of glioblastoma spheroid cells treated with IUdR or nanoparticles as IUdR carriers. However, the extent of reduction in colony number following treatment with IUdR-loaded nanoparticles in combination with hyperthermia and then X-ray radiation was significantly more than free IUdR. CONCLUSION: According to this study, PCL-PEG-coated magnetic nanoparticles are effective delivery vehicles for IUdR into cells. Moreover, they can act as a radiosensitizer and thermosensitizer in the treatment of the glioblastoma cell line.

Evaluation of the effect of hyperthermia and electron radiation on prostate cancer stem cells.

The aim of this study was to investigate the effect of hyperthermia, 6 MeV electron radiation and combination of these treatments on cancer cell line DU145 in both monolayer culture and spheroids enriched for prostate cancer stem cells (CSCs). Flowcytometric analysis of the expression of molecular markers CD133+/CD44+ was carried out to determine the prostate CSCs in cell line DU145 grown as spheroids in serum-free medium. Following monolayer and spheroid culture, DU145 cells were treated with different doses of hyperthermia, electron beam and combination of them. The survival and self-renewing of the cells were evaluated by colony formation assay (CFA) and spheroid formation assay (SFA). Flowcytometry results indicated that the percentage of CD133+/CD44+ cells in spheroid culture was 13.9-fold higher than in the monolayer culture. The SFA showed significant difference between monolayer and spheroid culture for radiation treatment (6 Gy) and hyperthermia (60 and 90 min). The CFA showed significantly enhanced radiosensitivity in DU145 cells grown as monolayer as compared to spheroids, but no effect of hyperthermia. In contrast, for the combination of radiation and hyperthermia the results of CFA and SFA showed a reduced survival fraction in both cultures, with larger effects in monolayer than in spheroid culture. Thus, hyperthermia may be a promising approach in prostate cancer treatment that enhances the cytotoxic effect of electron radiation. Furthermore, determination and characterization of radioresistance and thermoresistance of CSCs in the prostate tumor is the key to develop more efficient therapeutic strategies.

Enhancing the properties of beam forming bolus in hyperthermia: numerical simulation and empirical verification.

In this paper we present a simulation study of the induced specific absorption rate (SAR) within the phantom produced by radiofrequency radiation from a 8 MHz capacitive applicator. The main focus of the current study is on demonstrating the beam shaping properties of the bolus system as well as its effect on controlling the therapeutic area. Different electrical conductivities and geometries of the bolus were considered in the simulation of induced SAR distributions in a muscle-equivalent model with uniform dielectric properties. To validate the presented model, we carried out a comparison between the SAR simulation results and the temperature measurements in an agar split-phantom and an excellent agreement was observed.