Figure 3.

CD70 gene expression in osteosarcoma lesions does not influence survival. (A) CD70 protein expression (fold change geoMFI) on the surface of established osteosarcoma cell lines, as analyzed by flow cytometry (Figure 1), was correlated with relative CD70 gene (mRNA) expression of these cell lines, as analyzed by microarray. The regression coefficient (r²) between CD70 protein and CD70 gene expression was 0.87 (p = 0.002) as calculated by linear regression analysis. (B) CD70 relative gene (mRNA) expression in 83 biopsies of the primary tumor of 83 osteosarcoma patients depicted with the median and interquartile range. Elevated CD70 gene expression was evaluated as above the upper 25 percentile (16 patients, as indicated by the closed symbols). Asterix: biopsy L1372 of osteosarcoma patient 88 with high CD70 gene expression and available frozen tissue for immunohistochemical and immunofluorescent protein stainings as depicted in Figure 4. (C) Metastasis-free survival of osteosarcoma patients during ten years of follow-up comparing survival with high and low CD70 gene expression. Of the 83 patients (n = 16: CD70^high gene expression and n = 67: CD70^low gene expression) depicted in panel B, 13 patients with metastasis at time of diagnosis were excluded, resulting in the inclusion of 70 patients (n = 15: CD70^high, and n = 55: CD70^low) for this analysis. Mantel-Cox univariate survival analysis resulted in a log-rank χ² score of 0.29 (p = 0.59).