PTOP and TRF1 help enhance the radio resistance in breast cancer cell

Zheng Li,Fuxiang Zhou,Yunfeng Zhou,Nengxing Xia,Conghua X,Haijun Yu,Lei Yang,Xiaoxi Yang

doi:10.1186/1475-2867-14-7

Abstract

PurposeThe telomere binding proteins play an important role in telomere function, which contribute greatly to the radio resistant in human cancers. This research is designed to investigate the relationship among the telomere length, telomerase activity and changes of telomere binding protein PTOP and TRF1 in radio resistant breast cancer cell lines.MethodsIrradiate MDA-MB-435 s breast cancer cell with total dose of 60 Gy delivered in 2 Gy/fraction and 6 Gy/fraction respectively, then measuring their telomere length by Southern blot analysis,telomerase activity by Telomerase PCR Elisa and detecting the expression of PTOP and TRF1 in both gene and protein levels. To further investigate the function of PTOP, using lentivirus technic to silence the PTOP gene and the detected the new silenced cells by southern blot and telomerase activity.Results2 radio resistant breast cancer cell lines were successfully established. The MDA-MB-435 s R60/6 was (approximate 8.1-8.6 kbp) about 2–2.4 folds to the patent cell (3.6-4.2 kbp), the MDA-MB-435 s R60/2 cell (approximate 5.3-6.3 kbp) was about 1.3-1.75 fold to the parent cell line. The telomerase activity was more enhanced in radio resistant cell lines than the parent cell. The expression of PTOP and TRF1 were significant increased in radio resistant cell lines than the patent cell in both gene and protein level. Otherwise, after using lentivirus technic to silence the PTOP gene, we found the radio resistant cell lines were significant decrease their radio resistances and telomerase activities.ConclusionThe telomere binding protein PTOP and TRF1 were increased expressed in radio resistant breast cancer cell, PTOP was observed instinct positive correlated with telomere lengthen and telomerase activity enhancement.

Highlights

Telomere, caps the end of the mammalian chromosomes, is composed of repeated “5′-TTAGGG-3’” DNA sequences and telomere binding proteins, serves in the protecting of the degradation of chromosome and intracellular signaling for regulating cell proliferation [1,2,3]
Some research claim that the PTOP and Telomeric repeat binding factor 1 (TRF1) play an important role in interaction with other proteins and the length regulation has some relations to the telomerase activity [4,5]
The results suggested highly expressed PTOP and TRF1 had some relationship with radio resistance

Summary

Introduction

Caps the end of the mammalian chromosomes, is composed of repeated “5′-TTAGGG-3’” DNA sequences and telomere binding proteins, serves in the protecting of the degradation of chromosome and intracellular signaling for regulating cell proliferation [1,2,3]. The telomere binding proteins, called shelterin complex, contains PTOP, TRF1, TRF2, TIN1, TIN2 and POT1, are essentials for telomere function. Some research claim that the PTOP and TRF1 play an important role in interaction with other proteins and the length regulation has some relations to the telomerase activity [4,5]. Our previous research demonstrated there were some relationships with telomere length and cellular radio

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Discussion

Conclusion