Isotope tracing-assisted chip-based solid-phase extraction mass spectrometry for monitoring metabolic changes and vitamin D3 regulation in cells.

Cellular metabolism is a dynamic and essential process, with alterations in metabolic pathways serving as hallmark features of cancer. In this study, we developed a chip-based solid-phase extraction mass spectrometry (Chip-SPE-MS) platform for high-sensitivity, high-throughput analysis of cellular metabolites and real-time tracking of metabolic fluxes. The system achieved detection limits ranging from 0.10 to 9.43 μmol/mL for various amino acids and organic acids, with excellent linearity (r ≥ 0.992). By incorporating isotope tracing, the platform enabled derivatization-free, real-time monitoring of C-labeled metabolites, such as lactic acid. Our analysis revealed significant metabolic differences between normal (L02) and cancerous (HepG2, HCT116) cells, including enhanced glycolytic activity and elevated lactate production in cancer cells. Furthermore, treatment with 1,25-dihydroxyvitamin D3 was shown to suppress glucose uptake and modulate metabolic activity in HCT116 cells, highlighting the regulatory effects of vitamin D3 on cancer metabolism. This study not only provides novel insights into the metabolic reprogramming associated with cancer but also demonstrates the potential of the Chip-SPE-MS platform as a powerful tool for real-time monitoring of dynamic metabolic processes. The findings have broad implications for cancer therapy and the study of metabolic diseases.