Effect of combined action of doxorubicin and calcifediol on MCF-7 breast cancer cells

Introduction: Breast cancer is one of the most common cancers in women. Current recommendations for combination therapy in patients with breast cancer are still being developed and new therapies with greater success are sought. A relatively new approach is the administration of cytostatics in combination with vitamins. Hence, the study aimed to clarify whether the combination of calcifediol [25(OH)D3] with doxorubicin affects the response of the MCF-7 breast cancer cell line to the cytostatic. Material and methods: In the MCF-7 cell line, the authors assessed cytotoxicity using the MTT assay, analysed the cell cycle and cell death mechanism using flow cytometry, and examined the structure of the cytoskeleton and cell morphology. Results: The results showed that doxorubicin in combination with calcifediol in a 1:1 ratio showed a synergistic effect resulting in a dose-dependent decrease in cell survival. Further studies have shown that this is due to the pro-apoptotic and necrotic effects of the combination of these compounds. There were also changes in the organization of the cytoskeleton and cell morphology. In addition, features of entosis were noted in MCF-7 cells. Conclusion: The synergistic effect of doxorubicin and calcifediol significantly reduced the viability of MCF-7 breast cancer cells. Inducing the desired effect by lowering the cytostatic dose is of great clinical importance, taking into account the cardiotoxicity of doxorubicin. Another very interesting aspect is the entosis process induced in the present research, which may have a dual nature