Effect of high-dose Vitamin C combined with anti-cancer treatment on breast cancer cells

Background/Aim: The anti-cancer effect of high doses of intravenous vitamin C (high-dose vitamin C) remains controversial despite growing evidence that high-dose vitamin C exerts anti-tumorigenic activity by increasing the amount of reactive oxygen species in cancer cells without meaningful toxicities. Therefore, this study attempted to demonstrate the in vitro anti-cancer activity of high-dose vitamin C in combination with conventional treatment in breast cancer. Materials and Methods: The pro-apoptotic effects of high-dose vitamin C (1.25 to 20 mM) with or without anti-cancer agents (eribulin mesylate, tamoxifen, fulvestrant, or trastuzumab) were estimated using an MTT assay to measure the cell viability of a variety of breast cancer cell lines (MCF7, SK-BR3, and MDA-MB-231), as well as normal breast epithelial cells (MCF10A). Results: High-dose vitamin C (≥10 mM) significantly decreased cell viability of all breast cancer cell lines, particularly of MCF-7 cells. The catalase activities of MCF7 and MDA-MD-231 cells were also lower than those of MCF10A cells. Moreover, cell viability of both MCF7 and MDA-MD-231 cells was decreased further when combining high-dose vitamin C and eribulin mesylate, and this was also true for MCF-7 cells when combining high-dose vitamin C with tamoxifen or fulvestrant and for SK-BR3 cells when combining high-dose vitamin C with trastuzumab in comparison with chemotherapy or endocrine therapy alone. Conclusion: Combining high-dose vitamin C with conventional anticancer drugs can have therapeutic advantages against breast cancer cells.