Upregulation of Tyrosine Kinase FYN in Human Thyroid Carcinoma: Role in Modulating Tumor Cell Proliferation, Invasion, and Migration.

Tyrosine kinase FYN-a member of the SRC family of kinases-is associated with mediating mitogenic signals and regulating cell cycle entry, growth, and proliferation. It was hypothesized that FYN is upregulated in thyroid carcinoma, which plays a critical role in tumorigenesis. FYN expression level in thyroid carcinoma tissue and tumor cell lines was determined. Also, the effects of FYN on thyroid cancer (TC) growth, signaling, cell cycle, and apoptosis were evaluated in vitro. FYN was knocked down in thyroid cancer cells (TPC-1) by siRNA to investigate the effects on cell proliferation, invasion, and migration. First, FYN was upregulated both in thyroid carcinoma tissue and in tumor cell lines. Loss of FYN by siRNA weakened proliferation, invasion, and migration of PTC-1 cells. Furthermore, it was demonstrated that knockdown of FYN can inhibit the G0/G1 phase of cell cycle. It was also observed that reduced expression of FYN could increase the level of NF-κB/P65 and IκBα. This study was the first to demonstrate critical positive regulation of thyroid tumorigenesis by FYN, which could be a potential target gene for thyroid carcinoma treatment. In addition, findings from this study highlighted the potential role of FYN inhibitors in TC therapy.