Immunologically defined subclasses of the growth suppressor protein p53 detected with antibodies in sera from tumor patients.

Somatic mutation of the gene encoding the cellular p53 protein is the most common event in the development of human cancer. Patients with various types of cancer have circulating antibodies against p53. We screened sera of patients with different types of tumors. Some of the sera was used to precipitate p53 from different human tumor cell lines. Serum from a patient with breast cancer recognized wild-type and mutant form of p53 from an in vitro translation reaction. p53 recognized by this serum was found to be metabolically stable and phosphorylated in vivo. Furthermore, this serum recognized p53 in a complex with a protein kinase, which phosphorylated p53 in an in vitro phosphorylation reaction.