J Korean Soc Endocrinol.  2001 Feb;16(1):65-74.

The Expression of c-met Oncogene in Thyroid Tumor

• Lee WY
• lee YD
• Lee YJ
• Ryu GS

Abstract

BACKGROUND
The proto-oncogene c-met encodes the tyrosine kinase receptor for hepatocyte growth factor (HGF), which is a pleiotropic cytokine that controls growth, survival, motility, invasive migration, and differentiation of epithelial cells. Like several other epithelial neoplasms, thyroid carcinomas have been found to overexpress the c-met oncogene. We presently examine the expression of c-met protein in thyroid tumors and the correlation of c-met protein expression with prognostic factors in thyroid cancers. METHOD: We have examined the expression of the c-met oncogene in 62 paraffin-embedded thyroid cancer specimens (54 papillary carcinomas, 5 follicular carcinomas, 2 medullary carcinomas, and 1 anaplastic carcinoma), 20 benign tumors and 20 normal tissues using immunohistochemistry. We measured both the proportion and the intensity of stained cells and then calculated the staining index by multiplying the proportion and intensity scores. The staining index were categorized to be negative/low (staining index < or = 5) or high(staining index >5). The most important prognostic factors were age (over 45), tumor size (over 1.5 cm), lymph node metastasis, capsular invasion, vascular invasion and peripheral metastasis. RESULT: 1) The rate of expression of the c-met oncogene were 100%, 100% and 60% in thyroid cancer, benign tumors and normal thyroid tissue respectively. The expression of the c-met oncogene was restricted to the membrane. 2) The staining index of normal tissue, benign tumors and thyroid carcinomas was 1.8, 4.3 and 5.8 respectively. In malignancies, the staining index of papillary carcinoma was 5.7, follicular carcinoma 5.4, medullary carcinoma 7.5, and anaplastic cancer 9. 3) A high expression of c-met was not correlated with prognostic factors in papillary, follicular carcinomas or medullay carcinomas.
CONCLUSION
The c-met oncogene might not play a role in the pathogenesis of thyroid neoplasia. There was no correlation between the high expression rate of the c-met oncogene and prognostic factors in papillary and follicular carcinomas.

MeSH Terms

Carcinoma, Medullary
Carcinoma, Papillary
Epithelial Cells
Hepatocyte Growth Factor
Immunohistochemistry
Lymph Nodes
Membranes
Neoplasm Metastasis
Neoplasms, Glandular and Epithelial
Oncogenes*
Protein-Tyrosine Kinases
Proto-Oncogenes
Thyroid Gland*
Thyroid Neoplasms
Hepatocyte Growth Factor
Protein-Tyrosine Kinases