Loss of heterozygosity on chromosome 4q32-35 in sporadic basal cell carcinomas: evidence for the involvement of p33ING2/ING1L and SAP30 genes

Background: Studies on basal cell carcinoma (BCC) have demonstrated that patched gene and p53 gene located at 9q22.3 and 17p13 are the main genes responsible for the onset of this tumor. In order to identify a possible involvement of other tumor suppressor genes, we screened 19 cases of BCCs for loss of heterozygosity (LOH). Methods: The analysis was performed on tumoral tissue and on corresponding normal tissue by using a panel of 37 polymorphic markers spanning 26 chromosomal regions. Results: We observed that only four chromosomal regions, 4q32 (30.00%), 4q35 (27.27%), 9q21–22 (28.57%), and 9q22-qter (35.71%), demonstrated a significative LOH (>20%), even if others show a borderline percentage (15–20%) of imbalance (1q32, 3p24, 10p22.1, and 17q21.3). Conclusions: Our findings suggest that a new chromosomal region mapping in the long arm of chromosome 4 could be involved in sporadic BCC carcinogenesis. Further analyses indicate that the minimal deleted region in 4q32–35 includes p33ING2/ING1L and SAP30, whose deletion could impair the G1-phase checkpoint control and favor gene silencing, respectively.