PhD Scientific Days 2021

TT_II_L: Theoretical and Translational Medicine II. Lectures

Modulated Electro-hyperthermia Suppresses H19, a Tumor Promoting Long Non-coding RNA, and Promotes Antitumor Effect of Methotrexate in a Triple Negative Breast Cancer Model

Text of the abstract

Modulated electro-hyperthermia (mEHT) is a complementary antitumor therapy, based on selective tumor cell killing by a 13.56 MHz radiofrequency induced electric field. H19 long non-coding RNA (lncRNA) is involved in tumor progression and metastasis. Its overexpression is associated with poor prognosis in breast cancer. We observed previously significant tumor inhibitory effects of mEHT.
Our aim was to investigate mEHT related inhibition of H19 lncRNA alone or in combination with methotrexate in triple negative breast cancer (TNBC) models.
4T1 spheroids were embedded in Matrigel® and treated with mEHT for 30 minutes. Samples were collected 24 hours after treatment and processed for Real-Time qPCR. TNBC cells (4T1, 4T07, 67NR) were inoculated orthotopically in female BALB/c mice. Tumor growth was monitored in vivo by digital caliper and ultrasound. Mice were treated with mEHT in monotherapy or in combination with methotrexate (MTX) 2 or 3 times for 30 minutes with 0.7±0.3W power. The tumors were dissected and processed for molecular biologic techniques. H19 expression was measured with RT-qPCR, results were normalized to GAPDH.
H19 lncRNA expression correlated significantly with tumor aggressiveness in the TNBC models in vivo. Single mEHT treatment of 4T1 spheroids reduced significantly H19 expression compared to normothermic control (Ctr:0.004±0.0004, mEHT:0.0006±0.0002, p<0.0001) There was a significant decrease in H19 expression of 4T1 tumors after two (sham:0.068±0.044, mEHT:0.033±0.024, p<0.05) and three mEHT treatments (sham:0.097±0.059 vs mEHT:0.050±0.030, p<0.05) compared to the sham group. In case of combination treatments H19 expression was significantly lower in the mEHT+MTX group compared to MTX only (MTX:0.104±0,038 vs mEHT+MTX:0.056±0.025, p<0.01) and combinational therapy induced significantly stronger antitumor effect compared to any of the monotherapies.
Our results demonstrate, that mEHT can reduce the expression of tumor promoting H19 lncRNA in vitro and in vivo both in monotherapy and in combination with chemotherapy. Our findings suggest, that mEHT as an alternative complementary treatment could promote antitumor therapy by inhibiting the tumor progression mediating H19 lncRNA expression.
Funding: NVKP_16-1-2016-0042, KDP-2020/1007647, Semmelweis 250+ Kiválósági PhD Ösztöndíj

University and Doctoral School

Semmelweis University, Doctoral School of Theoretical and Translational Medicine