Interaction studies of carbon nanomaterials and plasma activated carbon nanomaterials solution with telomere binding protein

Pankaj Attri,Art E Cho,Minsup Kim,Naresh Kumar,Rohit Bhatia,Ji Hoon Park,Sooho Choi,Weontae Lee,Jitender Gaur,Eun Ha Choi

doi:10.1038/s41598-017-02690-4

Abstract

Most cancer cells have telomerase activity because they can express the human telomerase reverse transcriptase (hTERT) gene. Therefore, the inhibition of the hTERT expression can play an important role in controlling cancer cell proliferation. Our current study aims to inhibit hTERT expression. For this, we synthesized graphene oxide (GO) and a functionalized multiwall carbon nanotube (f-MWCNT), latter treated them with cold atmospheric pressure plasma for further analysis of the hTERT expression. The inhibition of hTERT expression by GO, f-MWCNT, plasma activated GO solution (PGOS), and plasma activated f-MWCNT solution (PCNTS), was studied using two lung cancer cell lines, A549 and H460. The hTERT experimental results revealed that GO and PGOS sufficiently decreased the hTERT concentration, while f-MWCNT and PCNTS were unable to inhibit the hTERT concentration. Therefore, to understand the inhibition mechanism of hTERT, we studied the binding properties of GO and PGOS with telomere binding protein (AtTRB2). The interaction studies were carried out using circular dichroism, fluorescence, 1H-15N NMR spectroscopy, and size-exclusion chromatography (SEC) binding assay. We also used docking simulation to have an better understanding of the interactions between GO nanosheets and AtTRB2 protein. Our results may provide new insights that can benefit in biomedical treatments.

Highlights

In all eukaryotes, telomeres are essential for genome stability, and any abnormalities in telomere functions can result in human aging and cancer[1]
A strong correlation exists between the presence of human telomerase reverse transcriptase (hTERT) mRNA and telomerase activity because hTERT expression depends on the rate of transcription[4, 6]
The treatment of the graphene oxide (GO) and functionalized multiwall carbon nanotube (f-MWCNT) solutions with atmospheric pressure plasma does not alter the structure of GO and f-MWCNT, but it resulted in generation of the reactive species into the solution

Summary

Introduction

Telomeres are essential for genome stability, and any abnormalities in telomere functions can result in human aging and cancer[1]. Chen et al showed that single walled carbon nanotubes (SWCNTs) can inhibit telomerase activity through the stabilization of i-motif structures[7]. They found that SWCNTs can induce the uncapping of telomere and remove the telomere-binding protein that results in the aberration of telomere and cell growth cessation. Synthesized the functionalization of MWCNT through the cycloaddition of aromatic azides, which results in detangled f-MWCNT, as described in earlier work[12, 13] Thereafter, both GO and f-MWCNT were dissolved in DI water and treated with plasma to generate the plasma activated GO solution (PGOS) and plasma activated f-MWCNT solution (PCNTS). To understand the hTERT expression inhibition mechanism, we studied the interaction properties of GO and PGOS with telomere binding protein, AtTRB2. We used docking simulation to better understand the interaction between GO nanosheets and AtTRB2 protein. 1H15N NMR and docking studies help to understand the role of specific amino acids that participate in binding

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