Electroporation enhances cell death in 3D scaffold-based MDA-MB-231 cells treated with metformin.

Triple-negative breast cancer (TNBC), the most aggressive subtype of breast cancer lacks estrogen, progesterone, and HER2 receptors and hence, is therapeutically challenging. Towards this, we studied an alternate therapy by repurposing metformin (FDA-approved type-2 diabetic drug with anticancer properties) in a 3D-scaffold culture, with electrical pulses. 3D cell culture was used to simulate the tumor microenvironment more closely and MDA-MB-231, human TNBC cells, treated with both 5 mM metformin (Met) and 8 electrical pulses at 2500 V/cm, 10 µs (EP1) and 800 V/cm, 100 µs (EP2) at 1 Hz were studied in 3D and 2D. They were characterized using cell viability, reactive oxygen species (ROS), glucose uptake, and lactate production assays at 24 h. Cell viability, as low as 20 % was obtained with EP1 + 5 mM Met. They exhibited 1.65-fold lower cell viability than 2D with EP1 + 5 mM Met. ROS levels indicated a 2-fold increase in oxidative stress for EP1 + 5 mM Met, while the glucose uptake was limited to only 9 %. No significant change in the lactate production indicated glycolytic arrest and a non-conducive environment for MDA-MB-231 growth. Our results indicate that 3D cell culture, with a more realistic tumor environment that enhances cell death using metformin and electrical pulses could be a promising approach for TNBC therapeutic intervention studies.

Enhancement of reactive oxygen species production in triple negative breast cancer cells treated with electric pulses and resveratrol.

Aim: Triple negative breast cancer (TNBC) is difficult to treat since it lacks all the three most commonly targeted hormone receptors. Patients afflicted with TNBC are treated with platinum core chemotherapeutics, such as cisplatin. Despite the initial effective anticancer effects of cisplatin, TNBC attenuates its effect and develops resistance eventually, which results in tumor reoccurrence. Hence, there is a critical demand for effective, alternative, and natural ways to treat TNBC. Towards this, a promising technique for inhibiting TNBC cell proliferation involves promoting the production of reactive oxygen species (ROS), which triggers pro-apoptotic caspases 9 and 3. Resveratrol (RESV), an active bio compound found in naturally available fruits, such as grapes, is utilized in this research for that. In addition, electrochemotherapy (ECT), which involves the application of electrical pulses (EP), was utilized to enhance the uptake of RESV. Methods: MDA-MB-231, human TNBC cells were treated with/out RESV, and eight 600-1,000 V/cm, 100 µs pulses at 1 Hz. The cells were characterized by using various assays, including viability assay, and ROS assay. Results: A TNBC cell viability of as low as 20% was obtained at 24 h (it was 13% at 60 h), demonstrating the potential of this novel treatment. ROS production was the highest in the combination of EP at 1,000 V/cm along with RESV at 100 µmol/L. Conclusions: Results indicate that RESV has the potential as an anti-TNBC agent and that EP + RESV can significantly enhance the cell death to reduce MDA-MB-231 cell viability by increasing ROS production and triggering apoptosis.

High-throughput, Label-free Proteomics Identifies Salient Proteins and Genes in MDA-MB-231 Cells Treated with Natural Neem-based Electrochemotherapy.

With the absence of the three most common receptor targets, and with high vascularity and higher-grade tumors, triple-negative breast cancer (TNBC) is the most aggressive of all breast cancer subtypes and is in need of additional/alternative/novel treatment strategies. With ~ 15% of the over 2 million new cases each year, there is an unmet need to treat TNBC. MDA-MB-231, human TNBC cells, were treated with neem leaf extract (Neem) and eight, 1200 V/cm, 100 µs electric pulses (EP), and their viability and proteomic profiles were studied. With EP + Neem, a lower viability of 37% was observed after 24 h, compared to 85% in the neem-only samples, indicating the efficacy of the combinational treatment. The proteomics results indicated significant upregulation of 525 proteins and downregulation of 572 proteins, with a number of different pathways in each case. These include a diverse group of proteins, such as receptors, heat shock proteins, and many others. The upregulated TCA cycle and OXPHOS pathways and the downregulated DNA replication and ubiquitin-mediated proteolytic pathways were associated with effective cell death, demonstrating the potency of this treatment. Viability results reveal the efficacious anticancer effects of the EP + Neem combination, via growth inhibition, on TNBC cells. Proteomics studies could readily identify the effected protein pathways, and their corresponding genes, that are responsible for cell death. This represents a potential therapeutic strategy against TNBC when patients are refractory to standard treatments.

Cisplatin-based Electrochemotherapy Significantly Downregulates Key Heat Shock Proteins in MDA-MB-231-Human Triple-Negative Breast Cancer Cells.

Heat shock proteins (HSPs) are available and/or induced for the survival of all organisms, including eukaryotic, prokaryotic, and plants, from higher temperature stresses. They are the chaperone proteins that protect all cells against heat, as the name implies. In addition to thermal stress, they also protect them from chemical, physical, and other stresses, including exposure to oxidative stress, nutritional deficiencies, ultraviolet radiation, ethanol, viral infection, ischemia-reperfusion injury, and cancer-related stresses. They are classified based on their molecular weights in kDa, such as HSP90 and HSP70. In our label-free, high-throughput, quantitative LC-MS/MS-based proteomic studies of MDA-MB-231, human, triple-negative breast cancer cells, treated with electrical pulses (EP) and cisplatin (CsP), we identified a number of HSPs, such as HSP90AA1, and others to be significantly downregulated in EP + CsP, compared to CsP alone. This indicates that cells will undergo apoptotic cell death and hence could cause effective cancer cure/treatment. Considering that over 2 million new cases and over 600,000 deaths in 2020, of which ~ 15% are TNBC, heat shock proteins could be the untapped resources, available for the next biomarkers and/or inhibitors for new/additional therapies.