Role of Platelet-Derived Growth Factor on the Fibrosis Process in Thyroid Carcinoma: Evaluation by Shear Wave Elastography.

OBJECTIVES: We aimed to determine the correlation between fibrosis and elastic values in papillary thyroid carcinoma (PTC) by shear wave elastography and to evaluate the effect of platelet-derived growth factor (PDGF) on the fibrosis process. METHODS: Small interfering RNA (siRNA)-PDGF and normal BCPAP cell lines were injected subcutaneously into the backs of nude mice. The elastic values of all tumors were measured by shear wave elastography. The content of collagen fibers and the expression of PDGF and type IV collagen (COL4) were evaluated by Masson staining and western blotting. RESULTS: There were 32 tumors in the control group and 30 tumors in the siRNA-PDGF group. The tumors were divided into 4 subgroups based on maximum diameters of the tumors. The mean elastic values +/- SD (Emean , 29.79 +/- 11.04 kPa; Emin , 16.98 +/- 7.51 kPa, Emax , 39.99 +/- 15.30 kPa; and SD, 5.92 +/- 2.00 kPa) in the siRNA-PDGF group were lower than in the control group (Emean , 35.73 +/- 18.49 kPa; Emin , 23.65 +/- 14.92 kPa, Emax , 45.73 +/- 22.88 kPa; and SD, 6.02 +/- 3.38 kPa). The content of collagen fibers and the expression of platelet-derived growth factor B (PDGFB) and COL4 proteins in the siRNA-PDGF group were lower than in the control group (11.43% +/- 6.99% and 19.80% +/- 11.70%; P = .010; 0.14 +/- 0.06 and 0.27 +/- 0.10; P = .002; and 0.11 +/- 0.06 and 0.15 +/- 0.07; P = .101). The elastic values, collagen fiber content, and PDGFB and COL4 in the 4 subgroups gradually increased with the maximum diameter of tumors. CONCLUSIONS: There was a positive correlation among PDGF, tumor stiffness, and fibrosis in the growth of PTC. Thus, PDGF might play an important role in the development of PTC.