EFFICIENT AND ECONOMICAL ELECTROCHEMOTHERAPY TREATMENTS FOR TRIPLE NEGATIVE BREAST CANCER: AN IN VITRO MODEL STUDY
With 2.1 million new cases, breast cancer is the most common cancer in women. Triple negative breast cancer (TNBC), which is 15-20% of these breast cancer cases is clinically negative for expression of estrogen and progesterone receptors (ER/PR) and human epidermal growth factor receptor 2 (HER2) receptors. It is characterized by its unique molecular profile, aggressive behavior, distinct patterns of metastasis, and lack of targeted therapies. TNBCs utilize glycolysis for growth, proliferation, invasiveness, chemotherapeutic resistance and hence has poor therapeutic response. There is an urgent need for novel/alternate therapeutic strategies beyond current standard of treatment for this subset of high-risk patients. Electrical pulse-based chemotherapy, known as electrochemotherapy (ECT) could be a viable option for TNBC therapy. ECT involves the local application of precisely controlled electrical pulses to reversibly permeabilize the cell membrane for enhanced uptake. ECT can increase the cytotoxicity of the chemotherapeutics up-to 1000 times, facilitating a potent local cytotoxic effect.
The high cost and severe side-effects of conventional chemotherapeutics motivate the application of effective natural compounds. Combining electrical pulses with natural compounds will enhance the treatment efficacy. This dissertation focuses on curcumin, the yellow pigment of natural herb turmeric, that has been used for over 5000 years for its excellent anticancer properties. Previous studies have demonstrated the effectiveness of curcumin for treating multiple cancers, including TNBC, with limited side effects. The potency of curcumin can be enhanced further by combining it with ECT to provide an attractive and cost-effective alternative for TNBC treatment.
Towards this we studied the effect of ECT with curcumin on MDA-MB-231 cell line, a human adenocarcinoma epithelial TNBC cell line. We performed various assays, including cell viability, colony forming, cell cycle, apoptosis, H2O2 reactive oxygen species (ROS), immunoblotting, real time quantitative PCR (qPCR), and cellular metabolites detection to study the impact of ECT with curcumin on MDA-MB-231 cells. In addition, to better understand the underlying mechanisms, we used high throughput, label-free quantitative proteomics. While several studies have attempted to define the mechanism of action of curcumin on cancer cells, little is known on the action mechanism of the curcumin delivered with electrical pulses. This work unravels the molecular mechanism behind the enhanced effects observed under the ECT-based curcumin therapy in TNBC cells, employing a high-throughput, quantitative, label-free mass spectroscopy-based proteomics approach. The proteomics approach provides information on the thousands of cellular proteins involved in the cellular process, allowing a comprehensive understanding of the electro-curcumin-therapy mechanism. Similar studies were also performed for ECT with cisplatin to compare the efficacy of the electro-curcumin-therapy to the standard stand-alone cisplatin-based therapy.
Our results revealed a switch in the metabolism from glycolysis to mitochondrial metabolic pathways. This metabolic switch caused an excessive production of H2O2 ROS to inflict apoptotic cell death in MDA-MB-231 cells, demonstrating the potency of this ECT based curcumin therapy. These results encourage further studies to extend the application of ECT for clinical practice.