Analysis of p53 and BAX mutations, loss of heterozygosity, p53 and BCL2 expression and apoptosis in basal cell carcinoma in Korean patients.

BACKGROUND

Apart from some Japanese studies, there are few data on the gene mutations involved in the development of basal cell carcinomas (BCC) in Koreans or other Asians. Objective To gain insight into the molecular pathogenesis of BCC in Koreans.

METHODS

A collection of 33 cases of BCC were screened for mutations of p53 and BAX genes, p53 and BCL2 expression, loss of heterozygosity (LOH) and apoptosis.

RESULTS

Mutations of p53, found in 9% (three of 33) of the cases, were all mis-sense mutations (G-->C transversions) at codon 246 on exon 7. In 6% (two of 33), BAX gene showed frameshift mutations resulting from deletions in the poly(G) tract. LOH on chromosome 9q was seen in 58% (14 of 24), and p53 mutations developed only among the 9q LOH+ cases; LOH on chromosome 18q, where BCL2 gene is located, was found in 13% (four of 30). Immunohistochemical expression of p53 was seen in 27% (nine of 33), and its expression did not coincide with p53 mutations. BCL2 expression was seen in 39% (13 of 33). Apoptosis was revealed in 21%. In BCC, 9q LOH and p53 mutations seem to be closely related; the immunoreactivity of p53 and its mutations were not directly related; and p53 and BCL2 expression were negatively correlated. Frameshift mutations of the BAX gene in BCC are documented for the first time.

CONCLUSIONS

Various molecular mechanisms operate with redundant complexity in the pathogenesis of BCC. The LOH on chromosome 9q is the most frequent genetic alteration, as in other races; however, p53 mutations are much less frequent in Koreans than in Caucasians and suggest aetiologies other than ultraviolet radiation.