A CODON 248 P53 MUTATION RETAINS TUMOR-SUPPRESSOR FUNCTION AS SHOWN BY ENHANCEMENT OF TUMOR-GROWTH BY ANTISENSE P53

Codon 248 in domain iv of the highly conserved region of the p53 gene is a frequent site of mutations associated with sporadic cancers and the familial cancer syndrome (Li-Fraumeni syndrome). Therefore, a characterization of the functional significance of a codon 248 mutation is of interest. We used antisense RNA methodology to study the role of the wild-type and mutated p53 gene in cell growth and tumorigenesis. We introduced wild-type p53 complementary DNA in sense or antisense orientation under control of a beta-actin promoter into human non-small cell lung cancer cell line H322a which has a codon 248 mutation (G to T) and WTH226b which has wild type p53. The biological properties and p53 expression of stable G418-resistant clones were analyzed. We observed that in both cell lines antisense RNA expression significantly reduced p53 mRNA and protein production; it also caused increases in growth rate in cell cultures and in tumorigenicity in nu/nu mice for both cell types, suggesting that the mechanism by which p53 suppresses cell proliferation and tumorigenesis is not always abrogated by a codon 248 mutation.