Expression of the components of the Cip/Kip family in malignant lymphoma of the thyroid.
OBJECTIVE
For evaluating the characteristics of human neoplasms, investigation of regulators of cell cycle progression is important. We studied three components of the Cip/Kip family, p57, p27 and p21, in malignant lymphomas of the thyroid.


METHODS
We immunohistochemically investigated the expression of the three proteins for 49 cases of thyroid lymphomas, as well as 10 cases of chronic thyroiditis.


RESULTS
In infiltrating lymphocytes in chronic thyroiditis, p57 and p27 were diffusely expressed, whereas p21 immunoreactivity was only occasionally observed. In lymphoma, decreased expression of p57 (less than 50% of lymphoma cells were positive) was observed in 24 cases (49.0%). p57 expression was inversely linked to the MIB-1 labeling index, grade of malignancy and aberrant p53 expression. Decreased expression of p27 was observed in 25 cases (51.0%), which was also related to the MIB-1 labeling index and aberrant p53 expression. On the other hand, p21 expression was occasional, and when the cut-off value was set at 3%, 38 cases (77.6%) were regarded as negative. P21 expression was not linked to any clinicopathological parameters.


CONCLUSIONS
These findings suggest that, among the 3 components of the Cip/Kip family, p57 and p27 play a role in negatively regulating the cell proliferation of thyroid lymphoma cells and decreased expression of them contributes to the progression of this disease.
Ito
Yasuhiro
Y
Kuma Hospital, Shimoyamate-dori, Chuo-ku, Kobe, Japan. ito01@kuma-h.or.jp
Yoshida
Hiroshi
H
Matsuzuka
Fumio
F
Matsuura
Nariaki
N
Nakamura
Yasushi
Y
Nakamine
Hirokazu
H
Kakudo
Kennichi
K
Kuma
Kanji
K
Miyauchi
Akira
A
D014408:Biomarkers, Tumor / Q000378:metabolism; D002455:Cell Division; D002908:Chronic Disease; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000378:metabolism*; D018450:Disease Progression; D006801:Humans; D007124:Immunoenzyme Techniques; D019394:Ki-67 Antigen / Q000378:metabolism; D008223:Lymphoma / Q000378:metabolism* / Q000473:pathology; D009687:Nuclear Proteins / Q000378:metabolism; D013964:Thyroid Neoplasms / Q000378:metabolism* / Q000473:pathology; D013966:Thyroiditis / Q000378:metabolism / Q000473:pathology
D014408:Biomarkers, Tumor; C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D019394:Ki-67 Antigen; D009687:Nuclear Proteins