Differences of the Immune Phenotype of Breast Cancer Cells after Ex Vivo Hyperthermia by Warm-Water or Microwave Radiation in a Closed-Loop System Alone or in Combination with Radiotherapy

Abstract

The treatment of breast cancer by radiotherapy can be complemented by hyperthermia. Little is known about how the immune phenotype of tumor cells is changed thereby, also in terms of a dependence on the heating method. We developed a sterile closed-loop system, using either a warm-water bath or a microwave at 2.45 GHz to examine the impact of ex vivo hyperthermia on cell death, the release of HSP70, and the expression of immune checkpoint molecules (ICMs) on MCF-7 and MDA-MB-231 breast cancer cells by multicolor flow cytometry and ELISA. Heating was performed between 39 and 44 °C. Numerical process simulations identified temperature distributions. Additionally, irradiation with 2 × 5 Gy or 5 × 2 Gy was applied. We observed a release of HSP70 after hyperthermia at all examined temperatures and independently of the heating method, but microwave heating was more effective in cell killing, and microwave heating with and without radiotherapy increased subsequent HSP70 concentrations. Adding hyperthermia to radiotherapy, dynamically or individually, affected the expression of the ICM PD-L1, PD-L2, HVEM, ICOS-L, CD137-L, OX40-L, CD27-L, and EGFR on breast cancer cells. Well-characterized pre-clinical heating systems are mandatory to screen the immune phenotype of tumor cells in clinically relevant settings to define immune matrices for therapy adaption.

Focused ultrasound radiosensitizes human cancer cells by enhancement of DNA damage

“…In early 1989, the effect of combined water bath HT and RT was published: higher cytotoxicity was observed 24 h after exposure to 43°C for 1 h and single-dose radiation at 5-10 Gy compared to RT alone [26]. Moreover, irradiation of 10 Gy and microwave-induced HT at 44°C for 1 h were reported to significantly enhance cell death of breast cancer cells 72 h after treatment [27]. The described effects of HT are intensively studied experimentally in vitro and in vivo in a high variety of cancer models [21].…”

Oncoimmunology Meets Organs-on-Chip

“…Despite the wide use of RT to overcome the main problem of cancer resistance, the mechanisms by which radiations activate immune system to kill cancer cells are still under intense debate. Tumor mouse models constitute an invaluable tool to carry out research on how immune system interacts with cancer cells in the TME under RT regimens ( Frey et al, 2012 ; Thiemann et al, 2012 ; Du et al, 2016 ; Dobiasch et al, 2017 ; Keisari, 2017 ; Bellia et al, 2019 ; Domankevich et al, 2020 ; Hader et al, 2020 ; Qin et al, 2020 ). The exploitation of animal models in this context has played a relevant role for the determination of radiation doses to be used to adequately activate immune cells, or certain type of immune cells, to efficiently eradicate cancer.…”

Modeling Radioimmune Response—Current Status and Perspectives

“…Notably, there are many more molecules involved in the immune checkpoints than the ones the checkpoints are named after, and the expression of these molecules is a dynamic process that may be modified also by other agents than radiation, e.g. heat ( 47 ). Again, models tend here to simplify the situation and model effectively the onset of immune activation triggered by radiation induced cell death.…”