Background: Intercellular adhesion molecule-1 (ICAM-1) is implicated in carcinogenesis. In this study we examined the expression of ICAM-1 in papillary thyroid cancer (PTC). We hypothesized that ICAM-1 correlates with indicators of tumor aggressiveness in PTC.
Methods: Thirty-five primary and metastatic PTCs, five follicular adenomas, five Hashimoto thyroiditis, five nodular hyperplasia, and eight normal thyroid tissue samples were analyzed for ICAM-1 gene expression using quantitative reverse-transcription polymerase chain reaction (RT-PCR). ICAM-1 gene expression was analyzed at protein level by immunohistochemistry (IHC) using a semiquantitative score. Gene expression and intensity levels were correlated with markers of tumor aggressiveness including BRAF V600E mutation, tumor size, extrathyroidal extension (ETE), angiolymphatic invasion, and lymph node metastasis.
Results: ICAM-1 gene expression was higher in PTC (p = 0.01) and lymph node metastases (p = 0.03) when compared with benign tumors and Hashimoto's. Furthermore, PTCs exhibiting BRAF V600E mutation (p = 0.01), ETE (p < 0.01), and lymph node metastasis (p = 0.02) were associated with higher ICAM-1 levels. Gene expression correlated with protein levels on IHC. Additionally, poorly differentiated thyroid carcinoma had a higher ICAM-1 intensity score compared with well-differentiated carcinoma (p = 0.03).
Conclusions: ICAM-1 expression is upregulated in papillary thyroid carcinoma. Furthermore, ICAM-1 upregulation correlated with aggressive tumor features such as BRAF V600E mutation, ETE, and lymph node metastasis, suggesting that ICAM-1 plays a role in thyroid cancer progression.