PROTEIN-KINASE-C-ALPHA AND TUMORIGENESIS OF THE ENDOCRINE GLAND

A point mutation in the protein kinase C alpha (PKC alpha) gene has be en discovered in a subpopulation of human pituitary tumors characteriz ed by their invasive phenotype. Here we show that: (1) thyroid tumors can express the PKC alpha mutation detected in a subpopulation of foll icular adenomas and carcinomas, and (2) mutated PKC alpha has modified enzymatic properties as compared to wild-type PKC alpha. It has lost its capacity to phosphorylate the S17R substrate and exhibits a higher sensitivity to degradation as compared to wild-type PKC alpha. In con clusion, the presence of the PKC alpha mutant in tumors other than pit uitary tumors and the observation that the presence of the point mutat ion induces changes in PKC alpha properties suggest the involvement of this mutant in tumorigenesis.