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Oncomedicine 2017; 2:71-79. doi:10.7150/oncm.18373 This volume Cite

Research Paper

Role of TRF2 in efficient DNA repair, spheroid formation and Cancer Stem Cell maintenance

Arka Saha^1*, SwatiShree Padhi^1*, Madhabananda Kar², Shomereeta Roy¹, Prasanta Maiti³, Birendranath Banerjee^1✉

1. Molecular Stress and Stem Cell Biology Group, School of Biotechnology, KIIT University, Bhubaneswar, Odisha-751024, India;
2. Department of Surgical Oncology, All India Institute of Medical Sciences, (AIIMS), Bhubaneswar, Odisha-751019, India;
3. Division of Research and Development, IMGENEX India Ltd, E-5, Infocity, Chandaka Industrial Estate, C S Pur, , Bhubaneshwar, Odisha- 751016.
*Contributed equally to this paper

✉ Corresponding author: Birendranath Banerjee, Group leader, Molecular stress and stem cell biology group, Disease Biology Lab, KIIT School of Biotechnology, KIIT University, Bhubaneshwar-751024, Odisha, India: Email: bnbanerjeeac.in, phone: +91-9090840042 Fax: 0674-2378776 More

Abstract

Chemotherapeutic resistance post-surgical management may be linked to an efficient DNA repair mechanism and survival of cancer stem cells. We report the presence of cancer stem cell like Side Population and their survival and enrichment post treatment with bleomycin in HCT116 cell line. The Side Population exhibited spheroidal characteristics and efficient repair of DNA damage foci compared to the parental HCT-116 cells. We report upregulated expression of β-catenin, TRF2, hTERT, CD44, CD24 and Oct4 genes in parental and clonospheres in a DNA damage environment. Comparative gene expression studies of parental and clonospheric HCT-116 cells revealed significant upregulation (p<0.01) of TRF2 gene in clonospheres. TRF2 which is a Telomere shelterin component is mainly involved in telomere maintenance and DNA repair. We report a role of TRF2 in cancer stem cell maintenance and efficient DNA repair in the clonospheric sub-population of HCT 116 cell line. Silencing of TRF2 gene significantly downregulated β-catenin, CD44, CD24, Oct4 and reduced the size of the clonospheres (4.448μm) when compared to scrambled non-silenced control (11.7273μm). TRF2 Silenced HCT116 parental cells reported compromised DNA repair and 2-fold increase in the number of DSBs as well as γH2Ax foci in the presence of a DSB generating agent Bleomycin, when compared to scrambled non-silenced control. In this study, we confirm a definitive role of TRF2 in stemness of cancer cells and DNA damage response and repair which is an extra-telomeric function and may have therapeutic implications in management of tumor recurrence.

Keywords: DNA Repair, TRF2, Clonospheres, Cancer Stem Cells, Stemness

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