Automated online monitoring of lactate and pyruvate in tamoxifen resistant MCF-7 cells using sequential-injection capillary electrophoresis with contactless conductivity detection (SI-CE-C4D) and correlation with MCT1 and MCT4 genes expression

Breast cancer is among the most common cancer types worldwide. The first and second line treatment protocols for various stages of breast cancer in females rely on tamoxifen. Until now, the development of tamoxifen resistance is not entirely understood. In this study, an automated sequential injection capillary electrophoresis with capacitively coupled contactless conductivity detector was developed for online levels monitoring of both lactate and pyruvate from the supernatant media of MCF-7 cells developing tamoxifen resistance. Changes in concentration of the two metabolites were simultaneously monitored from three model cell cultures and two control untreated cells. The electrophoretic separation was performed under reversed electroosmotic flow conditions. The system delivers high sample throughput at low sample consumption of 20 mu L per analysis. The method is robust and achieved high sensitivity and resolution. Limits of detection were 8.0 and 17.0 nM and linear ranges were 0.15-5 and 0.01-1 mM with a correlation coefficient of 0.9951 and 0.9963 for lactate and pyruvate, respectively. Inter-run and intra-run accuracy were in the range of 95.37-107.02% with precision (RSD, %) of <= 9.84%. The method was completely validated and the data obtained were in agreement with results achieved using the lactate and pyruvate assay kits. The highly informative generated data revealed a significant increase in lactate and pyruvate production in the three tamoxifen resistant MCF-7 cells models compared to the two control cells starting from 5.8 hours and 6.8 hours culturing times, respectively. The increase in concentrations of both lactate and pyruvate were correlated with an increase in MCT1 and MCT4 genes expression.

Automated summary

A new electrophoresis-based monitoring method was developed to study the metabolic changes in tamoxifen-resistant breast cancer cells, showing a significant increase in lactate and pyruvate production, correlated with increased expression of MCT1 and MCT4 genes.