tailieunhanh - Báo cáo khoa hoc : Mutant telomerase RNAs induce DNA damage and apoptosis via the TRF2-ATM pathway in telomerase-overexpressing primary fibroblasts

Mutant template human telomerase RNAs (MT-hTers) have been shown to induce apoptosis in various cancer cells with high telomerase activity. However, the mechanism by which MT-hTers inhibit the growth of cancer cells and their effects on normal cells remain unknown. | IFEBS Journal Mutant telomerase RNAs induce DNA damage and apoptosis via the TRF2-ATM pathway in telomerase-overexpressing primary fibroblasts Dashayini Mahalingam1 Ling L. Tay2 Wei H. Tan1 Juin H. Chai1 and Xueying Wang1 2 1 Department of Biochemistry Yong Loo Lin Schoolof Medicine National university of Singapore Singapore 2 Cancer Science Institute of Singapore NationalUniversity of Singapore Singapore Keywords apoptosis DNA damage IMR90 MT-hTers telomerase Correspondence X. Wang Department of Biochemistry Yong Loo Lin School of Medicine National University of Singapore MD7 8 Medical Drive 117597 Singapore Fax 65 6779 6831 Tel 65 6516 5995 E-mail bchwxy@ Received 26 April 2011 revised 14 July 2011 accepted 3 August 2011 doi Mutant template human telomerase RNAs MT-hTers have been shown to induce apoptosis in various cancer cells with high telomerase activity. However the mechanism by which MT-hTers inhibit the growth of cancer cells and their effects on normal cells remain unknown. To determine the effects of MT-hTers on normal cells MT-hTer-47A and -AU5 were introduced into IMR90 lung fibroblasts which have low telomerase levels. Growth of IMR90 cells after MT-hTers infection was not significantly impaired however similar treatments in telomerase-overexpressing IMR90 IMR90 wild-type WT hTERT cells inhibited cell proliferation and induced apoptosis. Confocal microscopy showed that MT-hTers induced DNA damage foci . 53BP1 and y-H2AX in IMR90 WThTERT cells. Microarray analysis revealed that GADD45c was significantly elevated in MT-hTer-treated IMR90 WThTERT cells. MT-hTers also induced ATM phosphorylation at Ser1981 in IMR90 WThTERT cells and western blot analysis revealed high levels of phosphorylated p53 after the down-regulation of cellular TRF2 expression in MT-hTer-treated IMR90 WThTERT cells. Taken together we have shown that MT-hTers induce doublestranded DNA break-like damages in telomerase positive IMR90 .