Vascular endothelial growth factor-C gene expression in papillary and follicular thyroid carcinomas

Background. Vascular endothelial growth factor-C (VEGF-C) is known to be related to development of lymphatic vessels. Papillary thyroid carcinoma characteristically metastasizes to regional lymph nodes, whereas follicular thyroid carcinoma commonly spreads hematogenously. The present study was designed to determine whether expression of the VEGF-C gene is related to the different metastatic features of these 2 types of thyroid carcinoma. Methods. Thyroid carcinoma specimens were obtained from 15 patients with papillary carcinoma and 4 patients with follicular carcinoma of the thyroid. VEGF-C gene expression was examined by Northern blotting and in situ hybridization. Immunohistochemistry was performed to localize the deposition of VEGF-C protein Results. The ratios of VEGF-C gene expression determined by Northern blot analysis were significantly higher in papillary than in follicular carcinoma. Nonmalignant thyroid tissue from patients with papillary carcinoma also expressed higher levels of VEGF-C than tissue from patients with follicular carcinoma. Expression of the VEGF-C gene was observed by in situ hybridization in cells of papillary thyroid carcinoma but not in those of follicular carcinoma. Positive staining with antibody against VEGF-C was detected in papillary cancer cells. Conclusions. Concurrent overexpression of the VEGF-C gene by both tumor cells and the surrounding tissue may be related to the prevalence of intrathyroidal spread through lymphatics and regional lymph node metastasis in patients with papillary thyroid carcinoma.