Figure 2.

Bicarbonate enhances the activity of doxorubicin in 4T1 breast cancer cells. (A) A schematic representation of the mechanism of doxorubicin uptake by cancer cells in acidic and neutral environments. (B+C) Cell viability was measured in representative physiological (7.4) and cancerous (6.5) pH. Doxorubicin (0.5μg/ml) with and without sodium bicarbonate (50mM), or HEPES, was added to cancer cells in culture, and cell viability was measured after 24 hours. (D+E) measurement of cell media pH change throughout the experiments. (F) Doxorubicin effect on cells’ viability with and without NaHCO₃ (50mM). a and a’ indicate p<0.05 while significant differences between groups b to b’, c to c’, d to d’ had p<0.01. (G) Cell viability (left axis) after treatment with different concentrations of NaHCO₃ (5-75mM) combined with doxorubicin, statistical significance (**p<0.01). Right axis presents media pH measurements during the experiment.

Error bars represent standard deviation from 3 to 5 independent repeats. *Significant difference between treatments, where *p<0.05, **p<0.01, ***p<0.001 according to a Student’s t-test with a two-tailed distribution with equal variance.