Downregulation of CXCR4 in dormant cancer cells in the human breast cancer patient-derived xenograft (PDX) model.

<p>(A) Heat map image of gene expression of 94 single breast cancer cells that were analyzed by the single-cell multiplex real-time quantitative reverse transcription PCR (RT-PCR) for 37 selected genes. Each of the squares filled with color shows the gene expression level of each single cell. Yellow indicates a high expression level, dark blue indicates a low expression level, and black indicates an undetectable level of gene expression. Green squares indicate the expression levels of <i>MKI67</i>, <i>GAPDH</i>, and <i>CXCR4</i>. Sky blue squares indicate cells showing undetectable expression levels of both <i>MKI67</i> and <i>CXCR4</i>. All cells showed an appropriate expression level of <i>GAPDH</i>. (B) Charts showing the relationship between the expression levels of <i>MIK67</i> and <i>CXCR4</i>. The results of the single-cell real-time quantitative RT-PCR were summarized. (C) Flow cytometric analysis of the expression level of cell surface CXCR4 and cell cycle of the cancer cells in the orthotopic tumors of the human breast cancer PDX. Representative histograms are shown.