Relationship Between RKIP Protein Expression and Clinical Staging in Thyroid Carcinoma

Raf-1 Kinase Inhibitory Protein (RKIP) belongs to a new class modulators of signalling cascades involved in maintaining of biological balance in many living organisms. RKIP targets and inhibits different kinases (Mitogen Activated Protein (MAP) kinase, G- protein coupled receptor (GPCR) kinase and nuclear factor kappa B (NF-�B) signaling pathways), and its loss is associated with progression of many solid cancers and development of metastasis. In this study we analyzed RKIP expression in follicular, papillary and undifferentiated thyroid carcinoma tissues from 54 patients by western blotting. We found that significantly reduced or lost RKIP expression was associated with lymph node (30 of 39 N1 tumors, 76.9%) and distant metastases (17 of 20 M1 tumors, 85%). No significant correlations were observed between RKIP ex- pression and T-category, age, gender, histological type or tumor differentiation grade. Our results indicate that reduction of RKIP expression is a highly predictive factor for lymph node and distant metastasis in patients with thyroid carcinoma.