PURPOSE: Doxorubicin is an anthracycline drug which inhibits the growth of breast cancer cell lines. However, a major factor limiting its use is a cumulative, dose-dependent cardiotoxicity, resulting in a permanent loss of cardiomyocytes. Vitamin C was found to potentiate the cytotoxic effects of a variety of chemotherapeutic drugs including doxorubicin. The aim of the study was to describe the changes in protein expression and proliferation of the MCF-7 cells induced by the vitamin C applied with doxorubicin. METHODS: Label-free quantitative proteomics and real-time cell analysis methods were used to search for proteome and cell proliferation changes. These changes were induced by the pure DOX and by DOX combined with vitamin C applied on the MCF-7 cell line. RESULTS: From the real-time cell analysis experiments, it is clear that the highest anti-proliferative effect occurs with the addition of 200 µM of vitamin C to 1 µM of doxorubicin. By applying both the label-free protein quantification method and total ion current assay, we found statistically significant changes (p ≤ 0.05) of 26 proteins induced by the addition of vitamin C to doxorubicin on the MCF-7 cell line. These differentially expressed proteins are involved in processes such as structural molecule activity, transcription and translation, immune system process and antioxidant, cellular signalling and transport. CONCLUSION: The detected proteins may be capable of predicting response to DOX therapy. This is a key tool in the treatment of breast cancer, and the combination with vit C seems to be of particular interest due to the fact that it can potentiate anti-proliferative effect of DOX.

Department of Chemical Drugs Faculty of Pharmacy University of Veterinary and Pharmaceutical Sciences Brno Czech Republic

Department of Internal Medicine IRCCS Policlinico San Matteo Foundation University of Pavia Pavia Italy

Department of Medical and Clinical Biophysics Faculty of Medicine Pavol Jozef Safarik University Trieda SNP 1 040 11 Kosice Slovakia

Department of Radiotherapy and Oncology Faculty of Medicine Pavol Jozef Safarik University East Slovakia Oncology Institute Kosice Slovakia

Department of Thoracic Surgery Faculty of Medicine and Dentistry Medical University of Silesia Katowice Poland

Institute of Histology and Embryology Faculty of Medicine University of Ljubljana Ljubljana Slovenia

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