LOW-RATE OF RET PROTOONCOGENE ACTIVATION (PTC RET(TPC)) IN PAPILLARY THYROID CARCINOMAS FROM SAUDI-ARABIA/

Background. The ret proto-oncogene activation (PTC/ref(TPC) oncogene) in thyroid papillary carcinoma has been reported in different populati ons with different frequencies. Thyroid papillary carcinoma appears to behave more aggressively in the Persian Gulf region than elsewhere. I n the current study, the frequency of PTC/ ret(TPC) oncogene in thyroi d tumors from Saudi Arabia was investigated. Methods. PTC/ret(TPC) onc ogene transcripts were analyzed by the polymerase chain reaction ampli fication of cDNA synthesized by treatment of total RNA with reverse tr anscriptase. Seven multinodular goiters, 1 follicular adenoma, 4 folli cular carcinomas, 40 papillary carcinomas, and 5 anaplastic carcinomas were studied. Results. Only one papillary carcinoma specimen was foun d to have PTC/ref(TPC) oncogene transcripts. The breakpoint of the rea rranged PTC/ret(TPC) oncogene is identical to that previously describe d. The PTC/ret(TPC) positive sample was also examined for p53 tumor su ppresser gene mutations in exons 5-8. One transitional point mutation was detected at codon 161 (GCC to ACC), changing Ala to Thr. Conclusio ns. This study questions the relevance of PTC/ret(TPC) oncogene in the carcinogenesis of thyroid papillary carcinomas in the Saudi populatio n. Genetic background among races may contribute to the different freq uencies of PTC/ret(TPC) oncogene in thyroid papillary carcinoma.