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KMID : 0616619990050010079
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Journal of Soonchunhyang Medical College
1999 Volume.5 No. 1 p.79 ~ p.90
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A Study for Expression Pattern of p53 Protein in the Epidermis Adjacent to Basal Cell Carcinoma
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Abstract
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The tumor suppressor gene, p53, has proved to be one of the genes most often modified in human cancers. These aterations consist mainly of point mutations located in the evolutionarily conserved sequences which render the protein inactive for its normal biologic functions. Many mutations of p53 result in a protein product that is abnormally stable, so it becomes readily detectable by immunochemistry.
Immunohistochemical overexpression of p53 has been observed not only invasive
tumors but also in precancerous or early lesions of tumors of the skin. Overexpression of p53 might be useful marker to identify precursor lesions of cancers arising de novo,
which are histopathologically indistinguishable from normal cell.
We were studied the p53 expressions immunohistochemically to identify a precursor lesion of basal cell carcinoma in the epidermis adjacent to basal cell carcinoma. With anti-p53 antibodies of DO7, p53 expression was frequently detected in the epidermis adjacent to basal cell carcinomas arising on the face and in the normal epidermis with usual sun exposure.
In the epidermis adjacent to basal cell carcinoma, stained cells were occasionally clustered in a small area, but no cluster was found in the normal epidermis with usual sun exposure. The expression was less frequent in the normal epidermis with rare sun exposure.
We have carried our PCR-sequencing of exon 5-8 of the p53 gene in 7 basal cell
carcinoma and two normal epidermis with immunohistochemically positive and cluster formed. Heterozygous mutations were detected in 4 of 7 (57%) samples investigated. All mutations were G:C-A:T transitions, three at codon 248 and one at codon 273. But no mutation was detected in two normal epidermis with cluster formed positive staining.
We conclude that
1. Because all basal cell carcinoma specimens examined here were obtained from facial lesions that were usually exposed to sunlight, the frequent p53 overexpression-detected in the epidermis adjacent to basal cell carcinoma might be related to chronic UV light exposure.
2. The accumulation of p53 was also frequently detected in the epidermis adjacent to basal cell carcinoma developing on the face that was usually sun-exposed.
In the epidermis adjacent to basal cell carcinoma, unlike normal epidermis with usual sun exposure that was scattered pattern, the stained cells were occasionally clustered in small areas of the epidermis.
3. A missense mutation was not found in the epidermis adjacent to basal cell
carcinoma.
4. The correlation between immunohistochemicl overexpression or pattern and
underlying mutation is not absolute, but there might be useful as excisional marker because the p53 staining positive cells ,that was clustered pattern, were possible result for clonal expansion of p53 mutant cells.
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