ROR1 is expressed in human breast cancers and breast cancer cell lines.

<p>(<b>A</b>) Representative images of fresh frozen tissue sections stained for immunohistochemistry with 4A5, a mAb specific for ROR1 (labeled anti-ROR1) or an IgG2b isotype-control mAb (labeled IgG). The bound antibody is red and the nuclear counterstain with hematoxylin is blue. Red arrow points to the tumor cells and blue arrow points to stromal cells. (<b>B</b>) Immunoblot analysis of lysates from normal human breast tissue or breast cancer tissue with rabbit antibodies specific for human ROR1 or β-Actin. CHO-ROR1 cells are CHO cells transfected to express human ROR1. (<b>C</b>) Fluorescence histograms of human breast cancer cell-lines (MCF-7, SKBR3, MDA-MB-431, MDA-MB-468, or MDA-MB-231) stained with 4A5 (open histograms) or control mAb (shaded histograms) (top panel). The expression of ROR1 mRNA in each tumor cell line relative to MCF-7 cells assessed via quantitative RT-PCR is indicated by the relative height of each bar below the corresponding histogram. The error bars represent the standard error about the mean of triplicate values. (<b>D</b>) Formalin-fixed, paraffin-embedded pellets of MCF-7 or MDA-MB-231 cells were stained with 4A5 or control IgG2b. Tissue-bound 4A5 is shown in red and the nuclear counterstain with hematoxylin is in blue (Scale bar in the top left picture represents 35 µm). (<b>E</b>) Representative images of breast normal tissues or cancer tissues stained with 4A5 A score of 0 indicates that none of the cells within the sample bound to the anti-ROR1 mAb; a score of 1 indicates low-level binding of the mAb to the tumor cells or low-to-moderate-level binding of the mAb on less than 50% of tumor cells; a score of 2 indicates moderate-level staining on more than 50% of tumor cells or high-level staining of the tumor cells. The scale bar in the top right picture represents 35 µM. Red arrows point to the tumor cells, blue arrow points to stromal cells and green arrow points to lymphocytes. (<b>F</b>) The proportion of breast tumor tissues or normal tissues found negative (Score 0) or having weak to moderate staining (Score 1) or strong staining (Score 2) for ROR1 are indicated by in each bar. The number of different cases examined for each tumor type is indicated in the parentheses. (<b>G</b>) The proportion of different histological types of breast tumor tissues found lacking staining (Score 0) or having weak to moderate staining (Score 1) or strong staining (Score 2) for ROR1 are indicated by in each bar. The number of different cases examined for each tumor type is indicated in the parentheses. (<b>H</b>) The proportion of poorly differentiated (grade 3) or well to moderately differentiated (grade 1–2) ductal breast adenocarcinoma tissues found lacking staining (Score 0) or having weak to moderate staining (Score 1) or strong staining (Score 2) for ROR1 are indicated by in each bar. The number of different cases examined for each tumor type is indicated in the parentheses. Statistical significance of the differences was analyzed using Kruskal-Wallis test (Grade 3 versus grade 1–2, P = 0.013).