BRAF mutations in papillary thyroid carcinoma.

Papillary thyroid carcinoma (PTC) is the most frequent malignant neoplasm of the thyroid originating from the thyroid follicular cell (TFC). Although the formation of PTC is believed to result from rearrangements of RET or TRK oncogenes or MET point mutations, these structural aberrations or point mutations do not correlate with the clinicopathological features of PTC and do not seem to be a useful prognostic marker of the disease. Therefore, further experiments should be carried out in order to find new practical clinical markers. Recently, oncogene BRAF has become a subject of great interest. The mutation of BRAF gene is characteristic for PTC and poorly differentiated and/or undifferentiated cancers derived from PTC. The occurrence of BRAF mutation has often been observed in various human tumours. The presence of mutation was confirmed in melanoma, colon cancer, gliomas and lung cancer. In the majority of cases, there is only one type of point mutation - V600E. The RAS/RAF/MEK/MAPK kinase pathway mediates the cellular response to mitogenic signals. BRAF gene mutation results in increased kinase activity, leading to excessive activation of the above mitogenic pathway and to uncontrolled proliferation of cancer cells. Some correlation was noticed between BRAF gene mutation and the clinical stage of the neoplastic disease in question. Preliminary investigations indicate that the presence of BRAF mutation might be a valuable diagnostic and prognostic marker of the disease. Further investigations could also bring further improvements into the therapeutic management of thyroid cancer. There are reports emphasizing the possibility of using the inhibitors of BRAF proteins in the treatment of PTC. Certainly, in order to confirm the diagnostic usefulness of this marker, further studies should be carried out.