CELL-PROLIFERATION IN HUMAN SOFT-TISSUE TUMORS CORRELATES WITH PLATELET-DERIVED GROWTH FACTOR-B CHAIN EXPRESSION - AN IMMUNOHISTOCHEMICAL AND IN-SITU HYBRIDIZATION STUDY

The authors tested the hypothesis that the B chain of the platelet-der ived growth factor (PDGF), a known connective tissue mitogen and growt h 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 t umors and all three grades of sarcomas, PDGF-B chain protein was local ized 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 tis sue sections of the same tumors. Sixty and 82% of tumors had demonstra ble PDGF-B mRNA and protein, respectively, with a strong correlation b etween 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 tum ors were also demonstrated to express the beta receptor of PDGF via im munohistochemistry. These studies suggest that PDGF-B expression may b e an important mediator of cell proliferation control, via an autocrin e mechanism, in human soft tissue tumors and may correlate with clinic al outcome in the sarcomas.