The authors tested the hypothesis that the B chain of the
platelet-derived growth factor (
PDGF), a known connective tissue
mitogen and
growth factor, could be expressed by human soft tissue
tumors, and that its expression could play a role in the control of cell proliferation in these
tumors. Using a set of 56 soft tissue
tumors, including benign
tumors and all three grades of
sarcomas, PDGF-B chain
protein was localized using immunohistochemistry and PDGF-B
mRNA was localized using in situ hybridization. The hypothesis that PDGF-B expression was related to cell proliferation was tested by simultaneously demonstrating the expression of the
proliferating cell nuclear antigen in sequential tissue sections of the same
tumors. Sixty and 82% of
tumors had demonstrable PDGF-B
mRNA and
protein, respectively, with a strong correlation between their degrees of expression (P = 0.0001). Among the
sarcomas, a strong correlation between PDGF-B expression and increasing malignant
tumor grade (P = 0.006), and between PDGF-B expression and increasing
proliferating cell nuclear antigen index (P = 0.01) was found. All
tumors were also demonstrated to express the beta receptor of PDGF via immunohistochemistry. These studies suggest that PDGF-B expression may be an important mediator of cell proliferation control, via an autocrine mechanism, in human soft tissue
tumors and may correlate with clinical outcome in the
sarcomas.