Platination of telomeric DNA by cisplatin disrupts recognition by TRF2 and TRF1

Abstract

Telomeres, the nucleoprotein complexes located at the ends of chromosomes, are involved in chromosome protection and genome stability. Telomeric repeat binding factor 1 (TRF1) and telomeric repeat binding factor 2 (TRF2) are the two telomeric proteins that bind to duplex telomeric DNA through interactions between their C-terminal domain and several guanines of the telomeric tract. Since the antitumour drug cisplatin binds preferentially to two adjacent guanines, we have investigated whether cisplatin adducts could affect the binding of TRF1 and TRF2 to telomeric DNA and the property of TRF2 to stimulate telomeric invasion, a process that is thought to participate in the formation of the t-loop. We show that the binding of TRF1 and TRF2 to telomeric sequences selectively modified by one GG chelate of cisplatin is markedly affected by cisplatin but that the effect is more drastic for TRF2 than for TRF1 (3-5-fold more sensitivity for TRF2 than for TRF1). We also report that platinum adducts cause a decrease in TRF2-dependent stimulation of telomeric invasion in vitro. Finally, in accordance with in vitro data, analysis of telomeric composition after cisplatin treatment reveals that 60% of TRF2 dissociate from telomeres.

Platinum Complexes Can Bind to Telomeres by Coordination

“…Moreover, we confirmed this result by UV melting temperature experiments. Since cisplatin GG adducts were known to affect the melting temperature of duplex oligonucleotides [ 54 ], we purified the cisplatin-GG adducts formed on the telomeric sequence (TTAGGG) 4 by gel electrophoresis, as previously described [ 44 ], and determined the UV melting temperature of its duplex form compared to the one of the non-modified duplex ( Figure S1b ). As expected, the presence of a cisplatin DNA-adduct reduces the melting temperature from 56 to 42 °C and, importantly, these conditions remain fully compatible with the telomere purification procedure.…”

“…The following data from the literature support this hypothesis. Unquestionably, in vitro studies have shown that cisplatin, a well-known chemotherapeutic agent that cross-links adjacent guanines [GG] in duplex DNA [ 39 ], binds efficiently to telomeric DNA with a two to three fold preference relative to genomic DNA, in accordance with the higher probability of finding adjacent guanines in telomeric DNA [ 40 , 41 , 42 , 43 ], and prevents TRF2 binding to telomeric DNA in vitro [ 44 ]. Moreover, a few studies have investigated the cellular effects of cisplatin [ 45 ] on telomeres, pointing out a possible interaction of this drug with telomeric DNA.…”

Expression of Telomere Repeat Binding Factor 1 and TRF2 in Prostate Cancer and Correlation with Clinical Parameters

“…The role of negative regulation of telomere terminus of TRF1 is mainly dependent on telomerase; its main function is to promote the T-loop formation located at telomere terminus. According to its role, TRF1 overexpression will shorten the telomere terminus length, thus contributing to tumor cells abnormal proliferation [ 14 – 16 ]. TRF2 does not depend on telomerase; the main role is to prevent telomere terminus fusion and maintain the genetic information and telomeres structure stable [ 17 , 18 ].…”

The Insertion in Fingers Domain in Human Telomerase Can Mediate Enzyme Processivity and Telomerase Recruitment to Telomeres in a TPP1-Dependent Manner

“…Ten picomoles of Alu and telomeric (T 2 AG 3 ) 3 probes were end labeled with 10 pmol of [␥-32 P]ATP (PerkinElmer) and purified using G-25 columns (GE Healthcare). Quantitation of telomere binding was done using the formula (telo IP/telo input)/(Alu IP/Alu input) (25), and values are expressed relative to WT telomerase binding to telomeres.…”