Department   Ritsumeikan Asia Pacific University  College of Sustainability and Tourism
   Position   Professor
Language English
Publication Date 2008/03
Type Research paper (Academic/Professional Journal)
Peer Review Peer reviewed
Title Foci formation of P53-binding protein 1 in thyroid tumors: activation of genomic instability during thyroid carcinogenesis.
Contribution Type Joint Work
Journal International journal of cancer
Volume, Issue, Page 122(5),pp.1082-8
Author and coauthor Nakashima M1, Suzuki K, Meirmanov S, Naruke Y, Matsuu-Matsuyama M, Shichijo K, Saenko V, Kondo H, Hayashi T, Ito M, Yamashita S, Sekine I.
Details Defective DNA damage response (DDR) can result in genomic instability (GIN) and lead to the transformation into cancer. P53-binding protein 1 (53BP1) belongs to a family of evolutionarily conserved DDR proteins. Because 53BP1 molecules localize at the sites of DNA double strand breaks (DSBs) and rapidly form nuclear foci, the presence of 53BP1 foci can be considered as a cytologic marker for endogenous DSBs reflecting GIN. Although it has been proposed that GIN has a crucial role in the progression of thyroid neoplasms, the significance of GIN during thyroid tumorigenesis remains unclear, particularly in patients. We analyzed, therefore, the level of GIN, as detected with immunofluorescence of 53BP1, in 40 cases of resected thyroid tissues. This study demonstrated a number of nuclear 53BP1 foci in thyroid cancers, suggesting a constitutive activation of DDR in thyroid cancer cells. Because follicular adenoma also showed a few 53BP1 nuclear foci, GIN might be induced at a precancerous stage of thyroid tumorigenesis. Furthermore, high-grade thyroid cancers prominently exhibited an intense and heterogeneous nuclear staining of 53BP1 immunoreactivity, which was also observed in radiation-associated cancers and in mouse colonic crypts as a delayed response to a high dose ionizing radiation, suggesting increased GIN with progression of cancer. Thus, the present study demonstrated a difference in the staining pattern of 53BP1 during thyroid carcinogenesis. We propose that immunofluorescence analysis of 53BP1 expression can be a useful tool to estimate the level of GIN and, simultaneously, the malignant potency of human thyroid tumors.