| Objective: Prevention by antioxidant agents including vitamin C (VC) and quercetin (QU), which are
nontoxic, cost effective, and physiologically bioavailable, is a promising approach in breast cancer
handling. The aim of this work is to investigate the influence of VCCQU on cytotoxicity profile of
doxorubicin (DOX) plus paclitaxel (PAC) in breast cancer cells. Methods: The effect of each drug on
its own or in combination was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium
bromide (MTT) assay. Combination indexes were calculated using the Chou–Talalay method.
Apoptosis and cell cycle analysis was investigated by flow cytometric assays. Results: Combination
treatment with VCCQU plus drugs diminished IC50 value 2.28–7.7 and 10.5–66.6 fold in comparison
with the drugs and PAC treatment alone, respectively, in all breast cancer cells and induced
apoptosis at the early stages more than the treatment with the drugs alone (P<0.01). A marked
reduction in Go/G1 and S phases was reported after combination therapy in MDA-MB 231 and
MDA-MB 468 cells. MCF-7 cells demonstrated lower fractions of cells in S phase with no significant
changes in G2/M phase (P < 0.01). The same treatment produced a significant increase in S and G2/
M phases in A549 cells (P < 0.001). Conclusion: Our results emphasized the importance of VCCQU in
combination with the drugs to produce a synergistic antitumor effect in breast cancer cells. |