Water bath hyperthermia reduces stemness of colon cancer cells

Photothermal treatment-based heat stress regulates function of myeloid-derived suppressor cells

Photothermal therapy is an alternative cancer therapy that uses a photothermal agent with light irradiation to induce fatal hyperthermia in cancer cells. In a previous study, we found that ex vivo photothermal (PT) treatment induced expression of heat shock proteins (HSPs), such as HSP70, HSP27, and HSP90, in cancer cells; moreover, immunization with lysates from PT-treated tumor cells resulted in significant tumor growth inhibition in tumor-bearing mice. In this study, we hypothesized that sublethal PT treatment of antigen-presenting cells regulates their immunogenicity. We observed the upregulation of expression of intracellular HSP70 and surface activation markers, such as CD40, CD80, CD86, and MHC class II, in sublethal PT-treated cells. The protumoral activity of myeloid-derived suppressor cells (MDSCs) was reduced by sublethal hyperthermia. Furthermore, poorly immunogenic MDSCs were converted into immunogenic antigen-presenting cells by PT treatment. The differences in immunogenicity between MDSCs untreated or treated with the PT technique were evaluated using the Student's t-test or Mann-Whitney rank sum test. Collectively, direct hyperthermic treatment resulted in phenotypic changes and the functional regulation of immune cells.

Targeting Stem Cells with Hyperthermia: Translational Relevance in Cancer Patients

BACKGROUND

Tumor recurrences or metastases remain a major hurdle in improving overall cancer survival. In anticancer therapy, some patients inevitably develop chemo-/radiotherapy resistance at some point. Cancer stem cells are the driving force of tumorigenesis, recurrences, and metastases, contributing also to the failure of some cancer treatments.

SUMMARY

Emergent evidence suggests that stem cell diseases are at the base of human cancers, and tumor progression and chemo-/radiotherapy resistance may be dependent on just a small subpopulation of cancer stem cells. Hyperthermia can be a strong cancer treatment, especially when combined with radio- or chemotherapy. It is a relatively safe therapy, may kill or weaken tumor cells, and significantly increases the effectiveness of other treatments. However, these mechanisms remain largely unknown. A literature search was performed using PubMed including cited English publications. The search was last conducted in December 2019. Search phrases included "stem cells," "hyperthermia," "cancer," and "therapy." Abstracts, letters, editorials, and expert opinions were not considered for the drafting of the study. Key Message: Our goal was to focus on and to summarize different biological features of cancer stem cells and new therapeutic approaches using hyperthermia and its potential translation to human clinical trials.

Cancer cells resist hyperthermia due to its obstructed activation of caspase 3

Aim

It is well known that inducing hyperthermia is a type of cancer treatment but some research groups indicate that this treatment is not effective. This article finds and explains the mechanism of this treatment and its possible problems.

Background

Hyperthermia is commonly known as a state when the temperature of the body rises to a level that can threaten one's health. Hyperthermia is a type of cancer treatment in which body tissue is exposed to high temperatures (up to 45 °C). Research has shown that high temperatures can damage and kill cancer cells, usually with minimal injury to normal tissues. However, this mechanism is not known.

Materials and Methods

We recently treated cancer cells with different temperatures ranging from 37 °C to 47 °C and further measured their caspase 3 secretion by ELISA, western blot and cell survival rate by microscope.

Results

We found that most cancer cells are able to resist hyperthermia more than normal cells most likely via non-activation of caspase3. We also found that hyperthermia-treated (≥41°) cancer cells extend a long pseudopod-like extension in comparison to the same cancer cells under normal conditions.

Conclusion

Our data here indicates that cancer cells have resistance to higher temperatures compared to normal cells via non-activation of caspase 3. This is a significant issue that needs to be brought to attention as the medical community has always believed that a high temperature treatment can selectively kill cancer/tumor cells. Additionally, we believe that the pseudopod-like extensions of hyperthermia-treated cancer cells must be related to its resistance to hyperthermia.

3D tumour spheroids for the prediction of the effects of radiation and hyperthermia treatments

For multimodality therapies such as the combination of hyperthermia and radiation, quantification of biological effects is key for dose prescription and response prediction. Tumour spheroids have a microenvironment that more closely resembles that of tumours in vivo and may thus be a superior in vitro cancer model than monolayer cultures. Here, the response of tumour spheroids formed from two established human cancer cell lines (HCT116 and CAL27) to single and combination treatments of radiation (0-20 Gy), and hyperthermia at 47 °C (0-780 CEM43) has been evaluated. Response was analysed in terms of spheroid growth, cell viability and the distribution of live/dead cells. Time-lapse imaging was used to evaluate mechanisms of cell death and cell detachment. It was found that sensitivity to heat in spheroids was significantly less than that seen in monolayer cultures. Spheroids showed different patterns of shrinkage and regrowth when exposed to heat or radiation: heated spheroids shed dead cells within four days of heating and displayed faster growth post-exposure than samples that received radiation or no treatment. Irradiated spheroids maintained a dense structure and exhibited a longer growth delay than spheroids receiving hyperthermia or combination treatment at (thermal) doses that yielded equivalent levels of clonogenic cell survival. We suggest that, unlike radiation, which kills dividing cells, hyperthermia-induced cell death affects cells independent of their proliferation status. This induces microenvironmental changes that promote spheroid growth. In conclusion, 3D tumour spheroid growth studies reveal differences in response to heat and/or radiation that were not apparent in 2D clonogenic assays but that may significantly influence treatment efficacy.

Magnetic Hyperthermia Using Self-Controlled Heating Elements Consisting of Fe-Al Milling Alloy Induces Cancer Cell Apoptosis while Preserving Skeletal Muscle

Necrosis-inducing anticancer drugs enhance high-mobility group box 1 (HMGB1) release during cell necrosis, and HMGB1-induced autophagy in skeletal muscle induces muscle atrophy. We evaluated the efficacy of magnetic hyperthermia therapy (MHT) using a low-energy magnetic field and self-controlled heating elements in tumor treatment. MHT-induced apoptosis by heating mouse subcutaneous tumors at 43°C using a heat-controlling iron-aluminum (Fe-Al) milling alloy. In contrast, MHT using Fe line-induced necrosis by heating to approximately 100°C. Furthermore, MHT with Fe-Al milling alloy reduced stemness. In hyperthermia using age line or Fe-Al milling alloy, both of them provided histological degeneration in skeletal muscle; however, qualitative differences were observed. MHT using Fe-line induced pronounced autophagy, decrease of myosin heavy chain content, and increase in serum HMGB1. In contrast, MHT using Fe-Al milling alloy induced heat shock protein 90 but no autophagy and decreased serum HMGB1. Therefore, MHT using Fe-Al milling alloy might be a good method for local treatment of tumors to reduce skeletal muscle atrophy.

Microwave hyperthermia promotes caspase‑3-dependent apoptosis and induces G2/M checkpoint arrest via the ATM pathway in non‑small cell lung cancer cells

Post-operative microwave (MW) hyperthermia has been applied as an important adjuvant therapy to enhance the efficacy of traditional cancer treatment. A better understanding of the molecular mechanisms of MW hyperthermia may provide guided and further information on clinical hyperthermia treatment. In this study, we examined the effects of MW hyperthermia on non-small cell lung carcinoma (NSCLC) cells in vitro, as well as the underlying mechanisms. In order to mimic clinical treatment, we developed special MW heating equipment for this study. Various NSCLC cells (H460, PC-9 and H1975) were exposed to hyperthermia treatment using a water bath or MW heating system. The results revealed that MW hyperthermia significantly inhibited cell growth compared with the water bath heating system. Furthermore, MW hyperthermia increased the production of reactive oxygen species (ROS), decreased the levels of mitochondrial membrane potential (MMP) and induced caspase-3 dependent apoptosis. It also induced G₂/M phase arrest through the upregulation of the expression of phosphorylated (p-) ataxia telangiectasia mutated (ATM), p-checkpoint kinase 2 (Chk2) and p21, and the downregulation of the expression of cdc25c, cyclin B1 and cdc2. On the whole, the findings of this study indicate that the exposure of NSCLC cells to MW hyper-thermia promotes caspase-3 dependent apoptosis and induces G₂/M cell cycle arrest via the ATM pathway. This preclinical study may help to provide laboratory-based evidence for MW hyperthermia treatment in clinical practice.

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.

In vitro comparison of conventional hyperthermia and modulated electro-hyperthermia

Radiofrequency-induced hyperthermia (HT) treatments for cancer include conventional capacitive coupling hyperthermia (cCHT) and modulated electro-hyperthermia (mEHT). In this study, we directly compared these methods with regard to in vitro cytotoxicity and mechanisms of action under isothermal conditions. Hepatoma (HepG2) cells were exposed to HT treatment (42°C for 30 min) using mEHT, cCHT or a water bath. mEHT produced a much higher apoptosis rate (43.1% ± 5.8%) than cCHT (10.0% ± 0.6%), the water bath (8.4% ± 1.7%) or a 37°C control (6.6% ± 1.1%). The apoptosis-inducing effect of mEHT at 42°C was similar to that achieved with a water bath at 46°C. mEHT also increased expression of caspase-3, 8 and 9. All three hyperthermia methods increased intracellular heat shock protein 70 (Hsp70) levels, but only mEHT greatly increased the release of Hsp70 from cells. Calreticulin and E-cadherin levels in the cell membrane also increased after mEHT treatment, but not after cCHT or water bath. These results suggest that mEHT selectively deposits energy on the cell membrane and may be a useful treatment modality that targets cancer cell membranes.

Continuous-wave Thulium Laser for Heating Cultured Cells to Investigate Cellular Thermal Effects

An original method to heat cultured cells using a 1.94 µm continuous-wave thulium laser for biological assessment is introduced here. Thulium laser radiation is strongly absorbed by water, and the cells at the bottom of the culture dish are heated through thermal diffusion. A laser fiber with a diameter of 365 µm is set about 12 cm above the culture dish, without any optics, such that the laser beam diameter is almost equivalent to the inner diameter of the culture dish (30 mm). By keeping a consistent amount of culture medium in each experiment, it is possible to irradiate the cells with a highly reproducible temperature increase. To calibrate the temperature increase and its distribution in one cell culture dish for each power setting, the temperature was measured during 10 s of irradiation at different positions and at the cellular level. The temperature distribution was represented using a mathematical graphics software program, and its pattern across the culture dish was in Gaussian form. After laser irradiation, different biological experiments could be performed to assess temperature-dependent cell responses. In this manuscript, viability staining (i.e., distinguishing live, apoptotic, and dead cells) is introduced to help determine the threshold temperatures for cell apoptosis and death after different points in time. The advantages of this method are the preciseness of the temperature and the time of heating, as well as its high efficiency in heating cells in a whole cell culture dish. Furthermore, it allows for study with a wide variety of temperatures and time durations, which can be well-controlled by a computerized operating system.

The role of HIPEC in the treatment of peritoneal carcinomatosis from gastric cancer: between lights and shadows

Gastric cancer is one of the most dreadful neoplastic diseases and remains the second cause of cancer death worldwide. Patients who develop peritoneal metastasis have a poor prognosis, with a median survival of less than 6 months. Despite being the cause of 60% of deaths from gastric cancer, peritoneal metastasis can still be considered a local disease and a local multidisciplinary approach can improve the prognosis even in this end-stage disease. At present, hyperthermic intraperitoneal chemotherapy (HIPEC) is the most widely accepted treatment for peritoneal surface diseases and can be performed in patients with different stages of cancer and with various antitumoral drugs. We performed a systematic review of the current status of HIPEC in the treatment of gastric peritoneal metastasis in an attempt to obtain answers to the questions that still remain: do results differ with these different methods? Does HIPEC exert a significant effect on the intracavitary delivery of drugs? Which patients should be treated and which should not? What can we expect from this approach in terms of survival, morbidity, and mortality? On reviewing the literature, despite the lack of trials comparing the different methods, we found that HIPEC has been shown to be an effective tool whenever a complete or an almost complete resection of the peritoneal implants can be performed. Therefore, it is advisable to refer all at-risk patients to specialized centers to be enrolled in randomized trials to achieve truly reliable results.

Influence of deep hyperthermia combined with systemic chemotherapy on overall survival of recurrent gastric cancer patients: Predictors of response to treatment

AIM: To investigate the effect of tumor deep hyperthermia combined with systemic chemotherapy on overall survival (OS) of recurrent gastric cancer patients, and to explore the predictors of response to the treatment.

METHODS: Ninety-nine patients with recurrent gastric cancer were divided into either a thermo-chemotherapy group (n = 42) or a control group (n = 57). The thermo-chemotherapy group was treated by deep tumor hyperthermia and chemotherapy, and the control group received systemic chemotherapy alone. The OS was compared for the two groups, and the predictors of response to individualized treatment was analyzed.

RESULTS: The median OS was significantly longer in the thermo-chemotherapy group than in the control group (18 mo vs 12.8 mo. (P = 0.003). In the thermo-chemotherapy group, the OS of patients with albumin (ALB) ≥ 35 g/L (19 mo) was better than that of patients with ALB < 35g/L (10 mo) ((P = 0.027); and the OS of patients with a neutrophil/lymphocyte ratio (NLR) < 4.558 (33 mo) was superior than that of patients with an NLR ≥ 4.558 (10 mo) ((P = 0.007).

CONCLUSION: For recurrent gastric cancer patients, thermotherapy combined with chemotherapy may be a more effective treatment option. Patients with normal serum ALB and an NLR < 4.558 may have a better prognosis. For patients with ALB < 35 g/L and an NLR ≥ 4.558, deep tumor hyperthermia combined with systemic chemotherapy is not recommended.

Cancer theranostics with gold nanoshells

Gold nanoshells (AuNSs) present a vivid example of integrating nanoscience in order to solve a biomedical problem. AuNSs exhibit tunable surface plasmon resonance, which can be tuned to the near-infrared region in order to realize optimal tissue penetration. The highly efficient light-to-heat transformation by AuNSs during laser irradiation causes thermal damage to the tumor without damaging healthy organs. Transient nanobubbles can form around AuNSs during laser treatment and induce mechanical stress specifically in tumor cells. AuNSs also serve as a versatile platform for the delivery of various diagnostic and therapeutic agents. In this article, we describe the physicochemical properties of AuNSs in the context of their design, preparation and application in cancer theranostics. Ultimately, we look beyond the current research on AuNSs and discussed future challenges to their successful translation into clinical use.