Mapping pH at Cancer Cell Surfaces
Date of Original Version
Purpose: To develop a tool to measure the pH at the surfaces of individual cells. Procedures: The SNARF pH-sensitive dye was conjugated to a pHLIP® peptide (pH-Low Insertion Peptide) that binds cellular membranes in tumor spheroids. A beam splitter allows simultaneous recording of two images (580 and 640 nm) by a CCD camera. The ratio of the two images is converted into a pH map resolving single spheroid cells. An average pH for each cell is calculated and a pH histogram is derived. Results: Surface pH depends on cellular glycolytic activity, which was varied by adding glucose or deoxy-glucose. Glucose was found to decrease the surface pH relative to the pH of the bulk solution. The surface pH of metastatic cancer cells was lower than that of non-metastatic cells indicating a higher glycolytic activity. Conclusions: Our method allows cell surface pH measurement and its correlation with cellular glycolytic activity.
Molecular Imaging and Biology
Wei, Da, Donald M. Engelman, Yana K. Reshetnyak, and Oleg A. Andreev. "Mapping pH at Cancer Cell Surfaces." Molecular Imaging and Biology 21, 6 (2019): 1020-1025. doi:10.1007/s11307-019-01335-4.