PhD Scientific Days 2023

Translational Medicine III.

Enhancement of Modulated Electro-Hyperthermia (mEHT) Effects by Heat Shock Factor 1 (HSF1) Inhibition in Triple Negative Breast Cancer (TNBC) Mouse Model

Text of the abstract

Introduction: Female breast cancer is the most diagnosed cancer worldwide. Triple negative breast cancer (TNBC) is the most aggressive type and is not sensitive to endocrine therapy. Modulated electro-hyperthermia (mEHT) is a non-invasive complementary tumor therapy using an electromagnetic field generated by amplitude modulated 13.56 MHz frequency that induces tumor cell destruction. However, we have demonstrated a strong induction of the heat shock response (HSR) by mEHT, which can result in thermotolerance.
Aim: We hypothesized that downregulation of HSF1 gene sensitizes the transfected tumor cells to mEHT and reduce tumor growth.
Method: A Balb/C isogenic murine TNBC cell line (4T1) was used. HSF1 CRISPR/Cas9 lentiviral knockdown or wild type 4T1 cells were inoculated into mammary gland’s fat pad. Further, wild type tumors were treated with the HSF-1 inhibitor KRIBB11, for 8 days. Four mEHT treatments were performed every two days and the tumor growth was followed by ultrasound and caliper.
Results: Tumor destruction histology and molecular expression changes were assessed. Reduction of tumor size and weight, and enlargement of tumor destruction area were observed in HSF1-KO mEHT-treated mice vs HSF1-KO Sham (HSF1-KO: 43.66 mg ± 20.09 mg; 84.45% ± 15.66% vs Sham: 110.0 mg ± 44.54 mg; 32.1% ± 14.52%, respectively) and Empty Vector mEHT-treated (89.49 mg ± 24.8 mg; 77.24% ± 7.34%, respectively). HSF1 mRNA level was significantly reduced in the KO group (Sham: 0.006180 ± 0.0006644; mEHT-treated: 0.005832 ± 0.001073) when compared to Empty Vector group (Sham: 0.01330 ± 0.002487; mEHT-treated: 0.01732 ± 0.004167). CRISPR/Cas9 lentiviral construct was able to diminish the induction of HSP70 mRNA expression (mEHT-treated: 0.01046 ± 0.005662) when compared to Empty Vector mEHT-treated group (0.02273 ± 0.01385). Immunohistochemistry confirmed the molecular data. Combined therapy of mEHT and KRIBB11 significantly reduced tumor weight (160.3 mg ± 33.26 mg) further compared to monotherapy (mEHT: 236.8 mg ± 46.42 mg; KRIBB11: 312.3 mg ± 41.45 mg).
Conclusion: Therefore, combined mEHT-therapy with HSF1 inhibition can be a possible new strategy of treating TNBC with a great translational potential.
Funding: Tempus Foundation – Stipendium Hungaricum scholarship; SE250+ EFOP-3.6.3-VEKOP-16-2017-00009; TÉT Brazil: 2021-1.2.4-TÉT-2021-00060; Ministry for Innovation and Technology and Hungarian National Research, Development and Innovation Office (ÚNKP-22-4-I-SE-15)