Genetic Alterations In Basal Cell Carcinoma.
M. D'Errico1,2, R. Corona2 and E. Dogliotti1*, 1Istituto, Superiore di Sanita', Rome, Italy; 2Istituto Dermopatico dell'Immacolata, Rome, Italy
p53 mutations in basal cell carcinoma (BCC) biopsies from patients belonging to different age groups (age 20-40, 40-60 and 60-80) were analysed. Preliminary data obtained on 13 subjects per group indicate that p53 mutations are not present in tumor biopsies from the age group 20-40, while the mutation frequency is approximately 30% above age 40. The type of mutations detected were exclusively base substitutions located at dipyrimidine sequences. Moreover, BCC patients with mutated p53 were typically those with outdoor work as assessed by questionnaire. These results suggest that cumulative sun exposure is responsible for accumulation of UV-specific p53 mutations. The same BCC were analysed by using microsatellite probes for chromosome 9. The frequency of LOH (mainly on chromosome 9q) ranged between 16-36%. The frequency of microsatellite instability ranged between 15-53% and was detected mainly on chromosome 9p. Interestingly, instability of chromosome 9 was observed at high rate also in the youngest age group (age 20-40), suggesting that chromosome instability is a key step in BCC development.