Early Changes in mRNA and Protein Expression Related to Cancer Treatment by Modulated Electrohyperthermia

Modulated electrohyperthermia (mEHT), generated by capacitive coupled, modulated 13.56？MHz radiofrequency, is a noninvasive technique for targeted tumor treatment based on elevated ion concentration and electric admittance in malignant tumors. In this study, we tested early changes in protein expression related to tumor destruction upon a single shot of 30-minute mEHT treatment of xenografted human colorectal cell line (HT29) implanted into the femoral region of Balb/c nu/nu mice. Treatment-related mRNA expression profiling was done using the human genome U133 Plus 2.0 Arrays. Apoptosis protein arrays and immunohistochemistry were performed for validating changes at the protein level. The mEHT treatment resulted in major expression changes in 48 genes including several heat-shock proteins. Apoptosis protein arrays revealed the upregulation of death receptors, Bcl-2 superfamily mitochondrial apoptosis regulatory proteins, and heat-shock proteins, which were also confirmed in situ. Within 24-hour post-treatment, mEHT resulted in the upregulation apoptosis induction and heat-shock-related gene and protein expression in HT29 colorectal cancer xenografts contributing to tumor destruction. 1. Background Modulated electrohyperthermia (mEHT) is a wildly used noninvasive technique for targeted tumor treatment [1–4]. The capacitive coupled modulated radiofrequency enriches in the tumor tissue (because of its dielectric differences [5]) without harming the surrounding nonmalignant tissues. Beside the temperature-dependent effect mEHT causes in the tumor tissue, it has a nontemperature-dependent tumor destruction effect, which is three times higher than the conventional hyperthermia with the temperature-dependent outcome only [6]. Here our aim was to study early changes in protein expression either related or not to the temperature changes in tumors treated with a single shot of mEHT. 2. Method HT29 human colorectal carcinoma cell line is xenografted to both femoral regions of Balb/c nu/nu mice. Tumors (approx. 1.5？cm diameter) were treated with a single-shot mEHT treatment (LabEHY, Oncotherm Ltd., Páty, Hungary) for 30 minutes. Temperature measurement was carried out during the treatment in the treated tumor core, and subcutaneously, in the opposite (treated control) tumor core and rectally. The treated tumor core temperature was between 41-42°C during the treatment. Sample was taken at 0, 1, 4, 8, 14, 24, and 48？h after the treatment with each group containing 3 mice alongside with 2 untreated control animals (sample was taken simultaneously with the 24？h treated