Preliminary study on the detection of hydrogen ion flux in breast cancer tissue using noninvasive microtest technology

Abstract Objective To detect the extracellular hydrogen ion (H+) flux of breast cancer tissue explants using noninvasive microtest technology (NMT) and assess how this flux correlates with the molecular subtype. Further more, we preliminarily explored the possibility of applying NMT as a treatment prescreening tool for predicting how docetaxel will affect tissue responses. Methods This study enrolled 30 breast cancer patients who underwent surgery in the Department of Breast Surgery at Beijing Hospital, Beijing, China. Tumor samples and the corresponding normal samples were excised from surgical specimens with a size of approximately 0.5 cm 3 . The NMT system was used to detect the H + flux of tumor samples and corresponding normal samples. Then, the NMT system was used to assess the changes in H + flux after the tumor samples were treated with 10 mg/L docetaxel. Results All the samples produced stable H + flux that could be measured in real time. In 26 cases, we found that tumor samples exhibited stable and robust efflux of H+, whereas in the corresponding normal samples, we measured significant differences with H + influx or mild efflux (cancer samples: 0.336 ± 0.307 pmol/cm − 2 /sec − 1 vs. normal samples: -0.067 ± 0.131, p < 0.001). Among the 26 tumor samples that showed efflux of H + , there were 4 luminal A type, 11 luminal B type, 6 HER2-positive type and 5 triple-negative type. Triple-negative tumors had a higher rate of H + efflux compared with luminal A, luminal B and HER2 positive tumors ( p = 0.016, p = 0.018, p = 0.008). Among the 4 tumor samples that were treated with docetaxel, 3 samples showed inhibition of H + efflux by 50.5%, 28.8% and 8.3%, while efflux increased by 30.0% in 1 sample. Conclusion NMT can detect the H + flux of breast cancer tissue in real time. The H + flux of tumor samples was significantly different from that of normal samples. After treatment with docetaxel, the H + flux of tumor samples showed definite changes.