Statistical Analysis of Ultrasonic Scattered Echoes Enables the Non-invasive Measurement of Temperature Elevations inside Tumor Tissue during Oncological Hyperthermia

Non-invasive monitoring of temperature elevations inside tumor tissue is imperative for the oncological thermotherapy known as hyperthermia. In the present study, two cancer patients, one with a developing right renal cell carcinoma and the other with pseudomyxoma peritonei, underwent hyperthermia. The two patients were irradiated with radiofrequency current for 40 min during hyperthermia. We report the results of our clinical trial study in which the temperature increases inside the tumor tissues of patients with right renal cell carcinoma and pseudomyxoma peritonei induced by radiofrequency current irradiation for 40 min could be detected by statistical analysis of ultrasonic scattered echoes. The Nakagami shape parameter m varies depending on the temperature of the medium. We calculated the Nakagami shape parameter m by statistical analysis of the ultrasonic echoes scattered from the tumor tissues. The temperature elevations inside the tumor tissues were expressed as increases in brightness on 2-D hot-scale maps of the specific parameter α_mod, indicating the absolute values of the percentage changes in m values. In the α_mod map for each tumor tissue, the brightness clearly increased with treatment time. In quantitative analysis, the mean values of α_mod were calculated. The mean value of α_mod for the right renal cell carcinoma increased to 1.35 dB with increasing treatment time, and the mean value of α_mod for pseudomyxoma peritonei increased to 1.74 with treatment time. The increase in both α_mod brightness and the mean value of α_mod implied temperature elevations inside the tumor tissues induced by the radiofrequency current; thus, the acoustic method is promising for monitoring temperature elevations inside tumor tissues during hyperthermia.

Comparison of biological effects of modulated electro-hyperthermia and conventional heat treatment in human lymphoma U937 cells

Loco-regional hyperthermia treatment has long history in oncology. Modulated electro-hyperthermia (mEHT, trade name: oncothermia) is an emerging curative treatment method in this field due to its highly selective actions. The impedance-matched, capacitive-coupled modulated radiofrequency (RF) current is selectively focused in the malignant cell membrane of the cancer cells. Our objective is studying the cell-death process and comparing the cellular effects of conventional water-bath hyperthermia treatment to mEHT. The U937 human histiocytic lymphoma cell line was used for the experiments. In the case of conventional hyperthermia treatment, cells were immersed in a thermoregulated water bath, whereas in the case of mEHT, the cells were treated using a special RF generator (LabEHY, Oncotherm) and an applicator. The heating dynamics, the maximum temperature reached (42 °C) and the treatment duration (30 min) were exactly the same in both cases. Cell samples were analysed using different flow cytometric methods as well as microarray gene expression assay and western blot analysis was also used to reveal the molecular basis of the induced effects. Definite difference was observed in the biological response to different heat treatments. At 42 °C, only mEHT induced significant apoptotic cell death. The GeneChip analysis revealed a whole cluster of genes, which are highly up-regulated in case of only RF heating, but not in conventional heating. The Fas, c-Jun N-terminal kinases (JNK) and ERK signalling pathway was the dominant factor to induce apoptotic cell death in mEHT, whereas the cell-protective mechanisms dominated in case of conventional heating. This study has clearly shown that conventional hyperthermia and RF mEHT can result in different biological responses at the same temperature. The reason for the difference is the distinct, non-homogenous energy distribution on the cell membrane, which activates cell death-related signalling pathways in mEHT treatment but not in conventional heat treatment.

Effects of nitrogen on the apoptosis of and changes in gene expression in human lymphoma U937 cells exposed to argon-based cold atmospheric pressure plasma

Cold atmospheric pressure plasma (CAP) is known as a source of biologically active agents, such as reactive oxygen species (ROS) and reactive nitrogen species (RNS). In the present study, we examined the effects of nitrogen (N2) on the apoptosis of and changes in gene expression in human lymphoma U937 cells exposed to argon (Ar)-CAP. Enormous amounts of hydroxyl (·OH) radicals in aqueous solution were produced using Ar‑CAP generated using a 20 kHz low frequency at 18 kV with a flow rate of 2 l/min. The increase in the levels of ·OH radicals was significantly attenuated by the addition of N2 to Ar gas. On the other hand, the level of total nitrate/nitrite in the supernatant was significantly elevated in the Ar + N2-CAP‑exposed U937 cells. When the cells were exposed to Ar‑CAP, a significant increase in apoptosis was observed, whereas apoptosis was markedly decreased in the cells exposed to Ar + N2-CAP. Microarray and pathway analyses revealed that a newly identified gene network containing a number of heat shock proteins (HSPs), anti-apoptotic genes, was mainly associated with the biological function of the prevention of apoptosis. Quantitative PCR revealed that the expression levels of HSPs were significantly elevated in the cells exposed to Ar + N2-CAP than those exposed to Ar‑CAP. These results indicate that N2 gas in Ar‑CAP modifies the ratio of ROS to RNS, and suppresses the apoptosis induced by Ar‑CAP. The modulation of gaseous conditions in CAP may thus prove to be useful for future clinical applications, such as for switching from a sterilizing mode to cytocidal effect for cancer cells.

Improving immunological tumor microenvironment using electro-hyperthermia followed by dendritic cell immunotherapy

Background

The treatment of intratumoral dentritic cells (DCs) commonly fails because it cannot evoke immunity in a poor tumor microenvironment (TME). Modulated electro-hyperthermia (mEHT, trade-name: oncothermia) represents a significant technological advancement in the hyperthermia field, allowing the autofocusing of electromagnetic power on a cell membrane to generate massive apoptosis. This approach turns local immunogenic cancer cell death (apoptosis) into a systemic anti-tumor immune response and may be implemented by treatment with intratumoral DCs.

Methods

The CT26 murine colorectal cancer model was used in this investigation. The inhibition of growth of the tumor and the systemic anti-tumor immune response were measured. The tumor was heated to a core temperature of 42 °C for 30 min. The matured synergetic DCs were intratumorally injected 24 h following mEHT was applied.

Results

mEHT induced significant apoptosis and enhanced the release of heat shock protein70 (Hsp70) in CT26 tumors. Treatment with mEHT-DCs significantly inhibited CT26 tumor growth, relative to DCs alone or mEHT alone. The secondary tumor protection effect upon rechallenging was observed in mice that were treated with mEHT-DCs. Immunohistochemical staining of CD45 and F4/80 revealed that mEHT-DC treatment increased the number of leukocytes and macrophages. Most interestingly, mEHT also induced infiltrations of eosinophil, which has recently been reported to be an orchestrator of a specific T cell response. Cytotoxic T cell assay and ELISpot assay revealed a tumor-specific T cell activity.

Conclusions

This study demonstrated that mEHT induces tumor cell apoptosis and enhances the release of Hsp70 from heated tumor cells, unlike conventional hyperthermia. mEHT can create a favorable tumor microenvironment for an immunological chain reaction that improves the success rate of intratumoral DC immunotherapy.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1690-2) contains supplementary material, which is available to authorized users.

EPR-Spin Trapping and Flow Cytometric Studies of Free Radicals Generated Using Cold Atmospheric Argon Plasma and X-Ray Irradiation in Aqueous Solutions and Intracellular Milieu

Electron paramagnetic resonance (EPR)-spin trapping and flow cytometry were used to identify free radicals generated using argon-cold atmospheric plasma (Ar-CAP) in aqueous solutions and intracellularly in comparison with those generated by X-irradiation. Ar-CAP was generated using a high-voltage power supply unit with low-frequency excitation. The characteristics of Ar-CAP were estimated by vacuum UV absorption and emission spectra measurements. Hydroxyl (·OH) radicals and hydrogen (H) atoms in aqueous solutions were identified with the spin traps 5,5-dimethyl-1-pyrroline N-oxide (DMPO), 3,3,5,5-tetramethyl-1-pyrroline-N-oxide (M₄PO), and phenyl N-t-butylnitrone (PBN). The occurrence of Ar-CAP-induced pyrolysis was evaluated using the spin trap 3,5-dibromo-4-nitrosobenzene sulfonate (DBNBS) in aqueous solutions of DNA constituents, sodium acetate, and L-alanine. Human lymphoma U937 cells were used to study intracellular oxidative stress using five fluorescent probes with different affinities to a number of reactive species. The analysis and quantification of EPR spectra revealed the formation of enormous amounts of ·OH radicals using Ar-CAP compared with that by X-irradiation. Very small amounts of H atoms were detected whereas nitric oxide was not found. The formation of ·OH radicals depended on the type of rare gas used and the yield correlated inversely with ionization energy in the order of krypton > argon = neon > helium. No pyrolysis radicals were detected in aqueous solutions exposed to Ar-CAP. Intracellularly, ·OH, H₂O₂, which is the recombination product of ·OH, and OCl^- were the most likely formed reactive oxygen species after exposure to Ar-CAP. Intracellularly, there was no practical evidence for the formation of NO whereas very small amounts of superoxides were formed. Despite the superiority of Ar-CAP in forming ·OH radicals, the exposure to X-rays proved more lethal. The mechanism of free radical formation in aqueous solutions and an intracellular milieu is discussed.

Abstract 3609: In vitro comparison of conventional hyperthermia and electro-hyperthemia

Purpose:

Deep heating hypertermia methods are a promising cancer treatment modalities used to enhance conventional treatment. This could be achieved through radiofrequency field en-bloc heating by Thermotron RF-8 and selective tumor heating by Oncotherm-Labehy, respectively. This is the first study to evaluate the different cytotoxic effect and action mechanism on cancer cells after mild hyperthermia (MHT) by Thermotron RF-8 or Oncothermia-Labehy.

Experimental Design:

Hepatoma HepG2 cells were used for MHT treatment (42°C for 30minute). Either by Oncotherm-Labehy or Thermotron RF-8 or water bath treatment were compared. Apoptosis evaluated 24h after MTH as measured by Annexin-V assay and cell cycle analysis. Mitochondria-targeted damage as measured by ROS production with or without Mito-TEMPO treatment and membrane-targeted damage as measured by caspase-8 expression, adhesion molecule expression, heat shock protein (HSP) release and calcium channel disturbance were evaluated and compared.

Results:

MHT resulted in similar cell cycle arrest on G2/M. Oncothermia treatment resulted in higher apoptosis rate (38.87±6.58) than RF-8 (25.13±2.26), water bath (18.77±0.35) and control (14.93±0.76). The expression of Caspase-8 is higher by oncothermia treatment, while caspase-3 and 9 levels were similar between 3 types of treatment. HSPs were upregulated by MHT, however a marked HSP release outside cell and E-cadherin overexpression on the membrane were only observed after oncothermia treatment.

Conclusion:

In this report, we found that different hyperthermia devices may induce different mechanisms on their cytotoxic effects and cell responses to heat. Oncothermia may selectively target on cell membrane before targeting on mitochondria, while RF-8 has no membrane targeting effect. These results may provide rational basis for future clinical application of hyperthermia treatment.

Citation Format: Kwan-Hwa Chi, Yu-Shan Samuel Wang, Cheng-Chung Huang, Chao-Chun Chang, Mau-Shin Chi, Kai-Lin Yang, Yuk-Wah Tsang, Gabor Andocs. In vitro comparison of conventional hyperthermia and electro-hyperthemia. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3609. doi:10.1158/1538-7445.AM2015-3609

Upregulation of heat shock proteins and the promotion of damage-associated molecular pattern signals in a colorectal cancer model by modulated electrohyperthermia

In modulated electrohyperthermia (mEHT) the enrichment of electric field and the concomitant heat can selectively induce cell death in malignant tumors as a result of elevated glycolysis, lactate production (Warburg effect), and reduced electric impedance in cancer compared to normal tissues. Earlier, we showed in HT29 colorectal cancer xenografts that the mEHT-provoked programmed cell death was dominantly caspase independent and driven by apoptosis inducing factor activation. Using this model here, we studied the mEHT-related cell stress 0-, 1-, 4-, 8-, 14-, 24-, 48-, 72-, 120-, 168- and 216-h post-treatment by focusing on damage-associated molecular pattern (DAMP) signals. Significant cell death response upon mEHT treatment was accompanied by the early upregulation (4-h post-treatment) of heat shock protein (Hsp70 and Hsp90) mRNA levels. In situ, the treatment resulted in spatiotemporal occurrence of a DAMP protein signal sequence featured by the significant cytoplasmic to cell membrane translocation of calreticulin at 4 h, Hsp70 between 14 and 24 h and Hsp90 between 24- and 216-h post-treatment. The release of high-mobility group box1 protein (HMGB1) from tumor cell nuclei from 24-h post-treatment and its clearance from tumor cells by 48 h was also detected. Our results suggest that mEHT treatment can induce a DAMP-related signal sequence in colorectal cancer xenografts that may be relevant for promoting immunological cell death response, which need to be further tested in immune-competent animals.

Modulated electro-hyperthermia enhances dendritic cell therapy through an abscopal effect in mice

The aim of this study was to assess whether modulated electro-hyperthermia (mEHT) can induce an abscopal effect and thereby enhance the antitumor effects of immunotherapy. We used an intratumoral dendritic cell (DC) injection and mEHT to treat C3H/He mice inoculated with squamous cell carcinoma SCCVII cells in the left leg, and we assessed the whole body antitumor effects. Tumors were examined every two or three days in order to assess growth inhibition. The tumor-draining lymph nodes were removed to enable flow cytometric analysis of CD3+ and CD8+ cells, whereas immunohistochemistry was used to assess CD8, S100 and Foxp3 expression in the tumors. Additionally, GP96 expression in the tumors from the different treatment groups was measured. In the control group, the mean tumor volume was larger than that in other groups. These results indicated that the combination therapy of an intratumoral DC injection and mEHT evoked systemic antitumor activity. A larger number of CD3+ and CD8+ cells were detected by flow cytometric analysis in the DC plus mEHT treatment group. Tumor tissue immunostaining showed that CD8 and S100 were more strongly expressed in the DC plus mEHT treatment group, although Foxp3 expression was much higher in the control group. The GP96 gene expression level in the mEHT group was significantly different from the expression level in the control group. An abscopal effect may be induced by mEHT, and the effect of immunotherapy with DCs was strongly enhanced by the overexpression of GP96. GP96 is thought to be one of the molecules explaining the abscopal effect. Direct intratumoral administration of DCs and mEHT may be a feasible future treatment strategy.

Oncothermia treatment of cancer: from the laboratory to clinic

Oncothermia is a long-time applied method (since 1989) in oncology. Its clinical results excellently show its advantages, however the details of its mechanism are under investigation even today. The method is based on a self-selective process of energy concentration and targets the membrane of the malignant cell, using the temperature gradient and the beta-dispersion of the membrane proteins. To prove the theory we show the experimental evidences in vitro experiments where we showed the definite difference between the conventional heating and the oncothermia at the same temperature. In the next step, we studied some xenograft nude-mice models, verifying the temperature-dependent and non temperature dependent factors. In addition, the synergic effect with some chemotherapies were studied, having more efficacy of the oncothermia with drugs than the conventional heating. These experiments show the definite advantages of the oncothermia compared to its classical counterpart, acting on the same temperature. We have also proved the beneficial effect of oncothermia treatment in the veterinary practice Oncothermia is applied in numerous clinics and hospitals, and we would like to show some characteristic case-reports and also the clinical benefit on the survival time elongation of liver-, pancreas-, brain-, and lung-tumor-lesions.

Do field-free electromagnetic potentials play a role in biology?

All bio-systems are imperfect dielectrics. Their general properties however cannot be described by conventional simple electrodynamics; the system is more complex. A central question in our present paper is centered on a controversial debate of the possible effect of the zero fields (only potentials exist). We show that the identical use of the "field-free," "curl-free," and "force-free" terminologies is incorrect, there have definitely different meanings. It is shown that the effective electro-dynamical parameters that describe and modify living systems are the potentials and not the fields. We discuss how the potentials have a role in biological processes even in field-free cases.

Strong synergy of heat and modulated electromagnetic field in tumor cell killing

BACKGROUND AND PURPOSE

Hyperthermia is an emerging complementary method in radiooncology. Despite many positive studies and comprehensive reviews, the method is not widely accepted as a combination to radiotherapy. Modulated electrohyperthermia (mEHT; capacitive, electric field modulated, 13.56 MHz) has been used in clinical practice for almost 2 decades in Germany, Austria and Hungary. This in vivo study in nude mice xenograft tumors compares mEHT with "classic" radiative hyperthermia (radHT).

MATERIAL AND METHODS

Nude mice were xenografted with HT29 human colorectal carcinoma cells. 28 mice in four groups with seven animals each and two tumors per animal (totally 56 tumors) were included in the present study: group 1 as untreated control; group 2 treated with radHT at 42 degrees C; group 3 treated with mEHT at identical 42 degrees C; group 4 treated with mEHT at 38 degrees C (by intensively cooling down the tumor). 24 h after treatment, animals were sacrificed and the tumor cross sections studied by precise morphological methods for the respective relative amount of "dead" tumor cells.

RESULTS

The effect of mEHT established a double effect as a synergy between the purely thermal (temperature-dependent) and nonthermal (not directly temperature-dependent) effects. The solely thermal enhancement ratio (TER) of cell killing was shown to be 2.9. The field enhancement ratio (FER) at a constant temperature of 42 degrees C was measured as 3.2. Their complex application significantly increased the therapeutic enhancement to 9.4.

CONCLUSION

mEHT had a remarkable cancer cell-killing effect in a nude mice xenograft model.

Usefulness of (99m)Tc(V)-dimercaptosuccinic acid scintigraphy in the assessment of response to external radiation therapy in soft tissue sarcoma in Giant Snauzer dog

A nine-year-old male black Giant Schnauzer dog was referred for the scintigraphic evaluation with a history of malignant fibrosarcoma with a rapidly growing non painful mass on the left shoulder region quite near to the site of an operation performed four months ago. We carried out oncological scintigraphy using pentavalent (99m)Technetium labelled dimercaptosuccinic acid [(99m)Tc(V)-DMSA], a tumour localising radiopharmaceutical agent. The study was performed to assess the margins, vascularity of the tumour and response to the cancer therapy. Uniform intense radiopharmaceutical uptake was observed in the lesion indicating its margins, vascularity and malignant nature. The dog was subjected to external radiation therapy to control the growth of the cancer and to bring the tumour mass to an operable size. The dog was followed up with (99m)Tc(V)-DMSA scintigraphy pre-irradiation and post-irradiation. Immediately after the post-irradiation scintigraphy, the dog was operated on. During the surgery, resection of the tumour margins was performed carefully using a hand held gamma probe to assure that no tumour tissue was left inside. In conclusion, the authors would like to state that (99m)Tc(V)-DMSA oncoscintigraphy is valuable in the assessment and evaluation of therapy in canine soft tissue cancer.