OBVIOUS MESSENGER-RNA AND PROTEIN EXPRESSION BUT ABSENCE OF MUTATIONSOF THE RET PROTOONCOGENE IN PARATHYROID TUMORS

The study on the expression of the RET proto-oncogene in parathyroid t umors disclosed obvious mRNA expression by the reverse transcription ( RT)-polymerase chain reaction (PCR) method and protein expression by W estern blotting. To find out whether mutations in the cysteine-rich re gions or tyrosine kinase domain of the RET proto-oncogene are etiologi cal for parathyroid tumorigenesis, sporadic parathyroid adenomas and c arcinomas, parathyroid tumors from multiple endocrine neoplasia 1, fam ilial isolated hyperparathyroidism or hereditary hyperparathyroidism-j aw tumor syndrome were screened by PCR-single strand conformation poly morphism and PCR restriction fragment length polymorphism. Missense mu tations in the cysteine-rich region, or codons 768 or 918 in the tyros ine kinase domain of the RET proto-oncogene, were not detected in any of the examined cases of parathyroid tumors. These results suggest tha t mutations of the RET proto-oncogene do not represent a frequent mech anism of tumorigenesis for parathyroid tumors.