The use of Human Inflammatory Response and Autoimmunity RT2 lncRNA PCR Array for plasma examination in breast cancer patients prior to therapy

Long non-coding RNAs (lncRNAs) are defined as RNA molecules longer than 200 nucleotides with poor protein-coding capacity and key functions in regulation of gene expression. Dysregulations of lncRNAs (e.g. HOTAIR and MALAT I) were detected in plasma of breast cancer (BC) patients. Plasma samples are examined as liquid biopsies for purposes of non-invasive diagnostics therefore the research of plasma lncRNAs as potential plasma biomarkers became highly topical. 84 lncRNAs were profiled in 18 plasma samples - 9 BC patients and 9 age-matched healthy - using Human Inflammatory Response & Autoimmunity RT2 lncRNA PCR Array. Total RNA from plasma samples was isolated using miRNeasy Serum/Plasma Kit. Although a pre-amplification recommended for quantification from small starting RNA amounts was used, only 3 lncRNAs (A2ML1-AS1, GAS5 and SNHG5) were detected in all plasma samples. A total of 72 lncRNAs (e.g. HOTAIR or MALAT I) were detected only in some samples and 9 lncRNAs were not detected in any samples. No significant differences were observed in levels of plasma lncRNAs between the BC patients and healthy controls despite the fact that our panel contained also the lncRNAs whose levels were previously reported as significantly different in plasma or cancer tissues (e.g. GAS5, HOTAIR, MALAT I) in BC patients. Detection of lncRNAs in plasma is due to their low concentrations quite difficult as compared with tissues. Our findings suggest that analysis of plasma lncRNAs using this technology is not suitable for use as non-invasive diagnostic tool in BC patients.