Telomerase activity of the cells during alteration of their proliferate states

We showed that telomerase activity (TAC) of human promyelocytic leukemic ce lls U-937 and HL-60 sharply decreased after induction of macrophagal differ entiation. Few days after inductor removal dedifferentiation occured that w as accompanied by proliferation resumption and TAC increase. TAC significan tly decreased also in the case of U-937 cell proliferation cessation in the course of long-term azidothymidine inhibition of telomerase function. A sl ow decrease in TAC during 6-8 days was observed in the course of transition of murine fibroblasts 3T3 Swiss to the quiescent state. TAC decreased in s erum-deprived cells. as well as in slowly proliferated high-density inhibit ed cells. During the quiescence exit and dedifferentiation, the increase in TAC preceded proliferation resumption. In all the described cases we obser ved correlations between TAC alterations and alterations in the nonspecific polymerase activity that we had found out earlier (Chernov D.N., Yegorov Y .E., Akimov S.S.//Doklady Biochemistry. 1996. V. 349. P. 55-58). The proble ms of TAC regulation are discussed.