Quantitative profiling of integrin αvβ3 on single cells with quantum dot labeling deeply revealed phenotypic heterogeneity of glioblastoma

Distribution, localization and density of individual molecules, e.g. drug specific receptors, on single cells are deep information of cell phenotypes. Profiling this information is a new research direction of single cell biology but remains technically challenging. By the combined use of quantum dot labeling, structured illumination microscopy (SIM) and a computer-aided local surface reconstruction, we acquired 3D imaging map of a drug target molecule integrin αvβ3 on glioblastoma cells at the single cell level. The results revealed that integrin αvβ3 exhibits discrete distribution on the surface of glioblastoma cell with density differing significantly among cell lines. The density is illustrated as the approximate number of target molecules per μm2 on the irregular cell surface, which ranges from 0 to 2. Functional studies revealed that the sensitivity of glioblastoma cells to inhibitor depends on the density of the target molecules. After inhibitor treatment, viability and invasion ability of different glioblastoma cells were highly correlated with the density of integrin αvβ3 on their surfaces. This study provides not only a novel protocol for quantitative analysis of surface proteins from irregular single cells, but also a clue to understand the heterogeneity of tumor cells on molecular phenotype basis, thus showing potential significance in guiding targeted therapies for cancers.