Patterns of cyclin A and B1 immunostaining in papillary thyroid carcinoma

Cyclin A, encoded by CCNA (cyclin A) gene with locus in chromosome 4q27, and cyclin B1, encoded by CCNB1 (cyclin B1) gene with locus in chromosome 5q12, are proteins that play a key role in the passage through the restriction point in G2 phase of the cell cycle. The aim of the study was to analyse immunohistochemically the expression of cyclins A and B1 in different variants of papillary thyroid carcinoma (PTC).

The immunostaining patterns of the proteins in question in the tissue of 40 resected PTC (20 cases of classic variant of PTC, 9 cases of PTC follicular variant and 11 cases of other non-classic variants of PTC) were investigated.

On analyzing cyclin A and B1 expression, positive staining in 90% cases of PTC were observed. The study revealed a significant difference in expression of cyclins A and B1 between classic and non-classic variants of PTC. The expression of both examined cyclins was weaker in the classic variant of PTC. In the group of follicular variant of PTC, the expression of cyclins was of medium intensity and in the group of other non-classic variants of PTC, the expression was clearly higher.

The results of the presented study suggest that cyclins A and B1 expression may have a characteristic pattern of immunostaining for particular variants of PTC. If the obtained results are confirmed in a larger group of patients, the diagnostic panel constructed of the antibodies against these proteins may increase the diagnostic accuracy in PTC cases.