Aims
To screen six candidate compounds – ivermectin, myricetin, amygdalin, prazosin, tamsulosin, and aripiprazole – for anti-cancer activity in breast cancer.
To determine whether the selected compounds enhance the cytotoxicity of doxorubicin when administered in combination.
Methods
The cytotoxic effects of the chosen compounds were evaluated in MDA-MB-231 and MCF-7 breast cancer cell lines. Compounds were treated on a logarithmic scale from 1µM to 300µM. Cell viability was determined using resazurin assays, and dose-response curves were generated to determine the half-maximal inhibitory concentration (IC50) of each compound. Based on the IC50 screening, the two most potent drugs were selected for subsequent combination studies with doxorubicin. Drug actions will be quantified using the Chou-Talalay method, with combination indices (CI) measured across different fractional affected values to classify drug interactions as synergistic, antagonistic, or additive. To investigate potential signalling mechanisms associated with treatment response, the most promising compound will be analysed using the R&D Systems Human Phospho-Kinase Antibody Array Kit. This array will simultaneously profile the phosphorylation status of 37 human kinases and expression of two additional signalling proteins in the chosen compound.
Results
IC50 experiments demonstrated differential sensitivity of MCF-7 and MDA-MB-231 cells to the six investigated compounds. Aripiprazole demonstrated an IC50 of 4.91µM in MDA-MB-231 cells and 15.08µM in MCF-7 cells, while ivermectin produced IC50 values of 8.30µM and 5.94µM, respectively. Based on the anti-proliferative activity of these compounds, aripiprazole and ivermectin were selected for subsequent combination studies with doxorubicin. Ongoing studies will determine the nature of these interactions using the Chou-Talalay method, and the most promising compound will be investigated for treatment-associated kinase signalling.
Conclusions
Preliminary findings suggest that aripiprazole and ivermectin exhibit the greatest antiproliferative activity against MDA-MB-231 and MCF-7 cells, with cell-line-dependent sensitivity. These findings support their further investigation in combination with doxorubicin and subsequent phosphor-kinase profiling.