ApeI/Ref-I expression and cellular localization in human thyroid carcinomacell lines

For its DNA repair, transcription factor regulation and anti-apoptotic acti vity, the apurinic/apirimidinic ApeI/Ref-I endonuclease is thought to play a relevant role in human tumorigenesis, In human thyroid tumors, we demonst rated an altered nuclear/cytoplasmic ratio in all the carcinomas examined b ut not in follicular adenomas, In this study, Ref-l expression and cellular localization were analyzed in a series of human thyroid carcinoma cell lin es. We found a reduced nuclear/cytoplasmic ratio in BCPAP, TPCI and ARO cel ls and not in WRO cells. Such a pattern of expression corresponds to that o bserved in thyroid tumoral tissues except for the WRO cells which behave as the follicular adenomas rather than carcinomas. Thus, these cell lines rep resent an excellent in vitro model to analyze the molecular mechanisms invo lved in Ref-I regulation and activity and clarify its role in thyroid tumor igenesis.