ABNORMALITIES OF RETINOBLASTOMA GENE STRUCTURE IN HUMAN LUNG-TUMORS

The retinoblastoma (Rb) gene is associated with the pathogenesis of several types of human cancer, including retinoblastoma, osteosarcoma, soft tissue sarcomas, and lung, breast and bladder carcinomas. Loss of heterozygosity is a common mode in allelic inactivation of Rb and other tumor-suppressor genes. We investigated DNA from 15 human lung tumors for loss of heterozygosity of the Rb locus using a polymerase chain reaction (PCR) based restriction fragment length polymorphism assay. Of informative cases we found loss of heterozygosity in 2 out of 3 squamous cell carcinomas and 1 out of 2 adenocarcinomas of the lung. We also found structural rearrangements in two out of fourteen Hind III digested lung tumors examined at the 5' region of the human Rb gene using Southern blot hybridization analysis. Since these two tumors were classified as stage III it is possible that the alteration of Rb gene is involved in the progression of this type of cancer. Using specific primers for exons 15, 16, 21 and 22 of the Rb gene, we carried out amplification of these exons by polymerase chain reaction. None of these tumors showed a deletion of exons 15, 16, 21 and 22.