Telomerase Activity and Expression of MIB-1 and bcl-2 in Human Chorionic Villi from Early and Term Normal Pregnancy

ABSTRACT

Telomerase is an enzyme that maintains telomeres and prevents telomere shortening, and may be linked with cellular proliferation or the aging process. The purpose was to examine telomerase activity in human chorionic villi from early and term normal pregnancies, and to analyze the correlation of telomerase activity (TA) with MIB-1 & bcl-2. A total of 37 placentae were obtained from 16 early and 21 term pregnancies. TA was assayed by telomeric repeat amplification protocol, and immunohistochemical staining was performed for MIB-1 & bcl-2 expression. TA & MIB-1 expression were strong in early placenta, but bcl-2 was highly expressed in term placentae. Thirteen (81.25%) of 16 early placentae showed TA, but only 2 (9.52%) of 21 term placentae expressed TA (p<0.01). MIB-1 was observed in nuclei of cytotrophoblast, and the expression rate was 16.09% in early placentae and 2.87% in term placentae (p<0.01). bcl-2 was observed only in the cytoplasm of syncytiotrophoblast. Term placenta demonstrated stronger expression of bcl-2 compared to early placentae (p<0.05). These findings suggest that TA, MIB-1 & bcl-2 expression are critically regulated over the course of gestation cytotrophoblast, main cells of early chorionic villi, may be a common source of telomerase and proliferative activity. The TA showed good correlation with cellular proliferative activity. Syncytiotrophoblast, may be a main source of bcl-2 expression which is stronger in the term placentae.