An amplification-free method for the detection of HOTAIR long non-coding RNA

The discovery of large transcripts of long RNAs that have limited protein coding capacity, known as long non-coding RNAs (lncRNAs) present new concepts on RNA-mediated gene regulation. Increasing evidence suggests that large intervening ncRNAs regulate key pathways in cancer genesis and metastasis. Among the most characterized lncRNAs, homeobox (HOX) transcript antisense intergenic RNA (HOTAIR) acts as an oncogenic molecule in different cancer cells, and thus its expression level serves as a potential biomarker for diagnostic and therapeutic purposes in several human cancers, such as breast, prostate, liver and ovarian cancer. This paper reports a simple and sensitive sensor platform for the detection of HOTAIR. Extracted HOTAIR sequences from ovarian cancer cells and plasma samples derived from ovarian cancer patients were magnetically isolated and purified, followed by a sandwich hybridization event at a screen-printed gold electrode. This event was monitored by amperometry using the hydrogen peroxide/horseradish peroxidase/hydroquinone (H₂O₂/HRP/HQ) system. The catalytic enhancement of the amperometric signal enabled our assay to achieve a detection limit of 1.0 fM with a good inter-assay reproducibility (relative standard deviation (%RSD) = < 5.0%, n = 3). The method was used for the analysis of specific HOTAIR in cell line and a small cohort of plasma samples derived from patients with ovarian cancer. The analytical performance of the method was also demonstrated using a standard RT-qPCR. We believe that the proof of the concept assay demonstrated here could be a cost-effective alternative platform for screening cancer-related lncRNAs in routine clinical settings.