Intracellular MicroRNA Quantification in Intact Cells: A Novel Strategy based on Reduced Graphene Oxide Based Fluorescence Quenching

The Delivery of Mimic miRNA-7 into Glioblastoma Cells and Tumour Tissue by Graphene Oxide Nanosystems

Purpose

The use of nanotechnology in medicine has gained attention in developing drug delivery systems. GO has the potential to deliver microRNA (miRNA) mimics or antisense structures. MiRNAs regulate gene expression and their dysregulation is implicated in diseases, including cancer. This study aims to observe changes in morphology, viability, mRNA expression of mTOR/PI3K/Akt and PTEN genes in U87, U118, U251, A172 and T98 glioblastoma cells and xenograft models after GO self-assembly with mimic miRNA-7.

Methods

Colloidal suspension of graphene oxide (GO) was used for obtaining the GO-mimic miRNA-7 nanosystems by self-assembly method. The ultrastructure, size distribution and ATR-FTIR and UV-Vis spectrum were analyzed. The Zeta potential was measured to verify the stability of obtained nanosystem. The entrapment efficiency, loading capacity and released kinetics of mimic miRNA-7 form GO-mimic miRNA-7 nanosystems were analyzed. The transfection efficiency into the glioblastoma cell lines U87, U118, U251, A172 and T98 of mimic miRNA-7 delivered by GO nanosystems was measure by confocal microscopy and flow cytometry. The changes at mRNA expression level of mTOR, PI3K, AKT1 and PTEN genes was measured by qPCR analysis. The xenograft model of U87 and A172 tumour tissue was performed to analyze the effect at tumor size and volume after GO- mimic miRNA-7 nanosystem administration.

Results

The ultrastructure of GO-mimic miRNA-7 nanosystems showed high affinity of mimic miRNA into the GO. The results of transfection efficiency, cell morphology and viability showed that GO -miRNA-7 effectively deliver mimics miRNA-7 into U87, U118, U251, A172 and T98 glioblastoma cells. This approach can reverse miRNA-7 expression's downstream effects and target the mTOR PI3K/Akt pathway observed at gene expression level, reducing xenograft tumour size and volume.

Conclusion

The findings of the study could have significant implications for the development of advanced and precise GO based nanosystems specifically designed for miRNA therapy in cancer treatment.

Influence of GO-Antisense miRNA-21 on the Expression of Selected Cytokines at Glioblastoma Cell Lines

Introduction

Graphene oxide (GO) is a single layer of carbon atoms with unique properties, which are beneficial due to its surface functionalisation by miRNA. miRNAs are a non-coding small form of RNA that suppress the expression of protein-coding genes by translational repression or degradation of messenger RNA. Antisense miRNA-21 is very promising for future investigation in cancer therapy. This study aimed to detect cytokine expression levels after the administration of GO-antisense miRNA-21 into U87, U118, U251 and T98 glioma cell lines.

Methods

U87, U118, U251 and T98 glioma cell line were investigated in term of viability, human cytokine expression level at protein and genes after treatment with GO, GO-antisense miRNA-21 and antisense miRNA-21. The delivery of antisense miRNA-21 into the glioma cell at in vitro investigation were conducted by GO based transfection and electroporation.

Results

The results of the protein microarray and gene expression profile showed that complexes of GO-antisense miRNA-21 modified the metallopeptidase inhibitor 2 (TIMP-2), interleukin-6 (IL-6), interleukin 8 (IL-8), intercellular adhesion molecule 1 (ICAM-1), and monocyte chemoattractant protein-1 (MCP-1) expression level compared to transfection by electroporation of antisense miRNA-21 at investigated glioblastoma cell lines. The TIMP-2 protein and gene expression level was upregulated after antisense miRNA-21 delivery by GO complex into U87, U251 and T98 glioblastoma cell lines comparing to the non-treated control group. The downregulation at protein expression level of ICAM - 1 was observed at U87, U118, U251 and T98 glioma cell lines. Moreover, the IL-8 expression level at mRNA for genes and protein was decreased significantly after delivery the antisense-miRNA-21 by GO compared to electroporation as a transfection method.

Discussion

This work demonstrated that the graphene oxide complexes with antisense miRNA-21 can effectively modulate the cytokine mRNA and protein expression level at U87, U118, U251 and T98 glioma cell lines.

Spectrochemical Probing of MicroRNA Duplex Using Spontaneous Raman Spectroscopy for Biosensing Applications

MicroRNAs are emerging as both diagnostic and therapeutic targets in different human pathologies. An accurate understanding of the structural dependency of microRNAs for their biological functions is essential for designing synthetic oligos with various base and linkage modifications that can transform into highly sensitive diagnostic devices and therapeutic molecules. In this proof-of-principle study, we have utilized label-free spontaneous Raman spectroscopy to understand the structural differences in sense and antisense microRNA-21 by hybridizing them with complementary RNA and DNA oligos. Overall, the results suggest that the changes in the Raman band at 785 cm^-1 originating from the phosphodiester bond of the nucleic acid backbone, linking 5' phosphate of the nucleic acid with 3' OH of the other nucleotide, can serve as a marker to identify these structural variations. Our results support the application of Raman spectroscopy in discerning intramolecular (ssRNA and ssDNA) and intermolecular (RNA-RNA, RNA-DNA, and DNA-DNA hybrids) interactions of nucleic acids. This is potentially useful for developing biosensors to quantify microRNAs in clinical samples and to design therapeutic microRNAs with robust functionality.