DETECTION OF MUTANT P53 IN CLAM LEUKEMIA-CELLS

Leukemia in the soft-shell clam, Mya arenaria, is characterized by tum or cells which are detected initially in the hemolymph. This disease i s much more common in clams inhabiting polluted waters, suggesting an environmental component to its pathogenesis. In this study, leukemia c ells were identified using a murine monoclonal antibody, 1E10, which r ecognizes a leukemia-specific protein expressed by tumor cells. Mutant p53 protein was detected using a murine monoclonal antibody (PAb 240) which reacts with mutant p53. Using immunofluorescence, the reactivit y of clam cells to the 1E10 antibody was evaluated along with mutant p 53 protein reactivity. Reverse transcriptase-polymerase chain reaction s followed by sequence analyses were utilized to examine clams with he mocytes reacting with the p53 antibody for possible p53 gene mutations . Mutant p53 protein was expressed by tumor cells from five animals wi th advanced disease (in which greater than 90% of cells reacted with 1 E10). A C --> G transversion was detected at the end of exon 6 from tw o of the five animals that reacted with both the mutant p53 antibody a nd 1E10. This substitution changes the amino acid of this codon from p roline to alanine. Overall, our results suggest that environmentally i nduced alterations in p53 can contribute to the pathogenesis of leukem ia in soft-shell clams inhabiting polluted water and/or sediment. (C) 1997 Academic Press.