Relationships between chromosomal patterns and protooncogenes in human benign salivary gland tumors.

By banding methods the chromosomes were studied in 20 cultured benign mixed salivary gland tumors. The results were considered together with the findings in 61 previously studied adenomas. About 55% of the 81 adenomas had a normal stemline. A total of 39 abnormal stemlines were found in the remaining 36 cases. The abnormal stemlines could be divided into four groups: 1) A large group with chromosome 8 involvement, mostly translocations of segments distal to 8q12; 2) A small group with chromosome 12 involvement, usually translocations of segments distal to 12q13-15;3) A small group with translocations and/or deletions affecting a distal segment of either the short or the long arm of chromosome 3; 4) A heterogeneous and small group with deviations related to those seen in variant cells in cases with normal stemlines. Comparisons with the known localization of proto-oncogenes revealed that almost 60% of the abnormal stemlines showed anomalies which could fit with oncogene activation. Future mapping studies of proto-oncogenes, as well as studies of combined actions of proto-oncogenes, different viral genes and some poorly understood oncogenic factors, will no doubt, enable a more complete characterization of the roles played by oncogenes in the genesis and progression of mixed tumors.