Leucine-rich repeat-containing
G-protein coupled receptor 5, or LGR5, is a molecule that recognizes stem cells in multiple organs and also in
colon cancer. Previously, we have developed
monoclonal antibodies specific to LGR5
protein that can be used for immunofluorescence staining, but because a very low level of LGR5
protein is expressed, the visualization technique needed to be enhanced. To develop procedures to detect LGR5
protein in various specimens by immunofluorescence staining, we evaluated the Alexa-labeled
streptavidin biotin (LSAB), the Qdot, and the tyramide methods. The detection sensitivity was highest in the tyramide method followed by the Qdot method, whereas subcellular localization of the
protein was most clear in the Qdot method, because the Qdot method gave a high S/N ratio that could show a low background. Thus, the tyramide method is superior to the Q-dot method for intensifying the signal of a low expression
protein, and the Qdot method is superior to the tyramide method for identifying the subcellular localization of the target
protein. The results of the present study will be helpful in providing more insight into the pathophysiological roles of LGR5-positive cancer stem cells and in developing therapeutic approaches for targeting cancer stem cells.