Genetic alterations in the retinoblastoma protein-related p107 gene in human hematologic malignancies

Genetic alterations in the p107 gene, a close relative of the retinoblastoma tumor suppressor gene, have never been identified in human malignancies. When we searched for such alterations in human hematologic malignancies by Southern blot analysis, 2 of 21 cell lines and 1 of 88 primary disorders had genomic alterations within the gene. Particularly, an altered p107 gene in a diffuse-large B-cell lymphoma cell line, KAL-1, harbored an intragenic deletion of about 15 kbp leading to the expression of an altered p107 mRNA devoid of 819 nucleotides of the coding sequences, which predicts to encode an approximately 87-kDa protein. This cell line was found to express solely a p107 derivative of 84 kDa by immunoblotting analysis. These results suggest that alterations in the p107 gene are probably related to a limited subset of human hematologic malignancies.