| Budget Amount *help |
¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 2000: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1999: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1998: ¥900,000 (Direct Cost: ¥900,000)
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| Research Abstract |
In the rat brains, the astrocytes were exclusively p27 positive, while reactive astrocytes in various disease processes sometimes lacked p27 expression. The distribution of p27 positive cells was uniform in low-grade astrocytomas, and heterogeneous in high-grade tumors. Double staining of p27 and MIB-1 showed a reciprocal pattern in most cases. The frequency of p27 expression inversely correlated with MIB-1 staining index and tumor grade. However, several malignant gliomas showed high p27 expression in spite of high MIB-1 staining indices. In such cases, MIB-1 positive cells were occasionally p27 positive. Presumably, high levels of cyclin D1 or E in these cells might compensate for the inhibitory effects of p27. Alternatively, overexpression of c-Myc could antagonize the p27 through unknown mechanisms.
In pituitary gland, p27 appeared to be a major growth suppressive factor. However, radiation induce the loss of p27 in contrast to the increase of p21 expression.
Expression of p27 was ob
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served in meningiomas. The relation between the proliferative indices and frequency of p27 expression was not distinct. However, we found that various clinical and radiological factors related to growth potential and recurrence rate of this tumor.
In craniopharyngiomas, MIB-1 immunohistochemistry revealed higher staining indices (SIs) in basal cells than in suprabasal cells. Interestingly, epidermoid cysts had higher SIs than craniopharyngiomas (12.6±5.4% vs. 4.8±3.0%, p<0.001). p27 was diffusely expressed in the suprabasal cells of the epidermoid cysts, while the expression was rare in craniopharyngiomas, espescially in squamous papillary type. Expression of p21 was rare in both types of tumors. Although TUNEL positive cells were detected in pre-keratinized cells in both tumors, the incidence was lower and irregular in craniopharyngiomas. Epidermoid cysts have as high a proliferating potential with balanced high cell loss rate as epidermis. On the other hand, craniopharyngiomas showed less cell proliferation with aberrant cell differentiation and cell loss. This appeared to be related to lower and irregular p27 expression, since p27 plays a significant role in differentiation of stratified squamous epithelium. Less
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