Nanodrop uv spectrophotometry platform

Cells were harvested by scraping and total RNA was extracted using miRNeasy Micro Kit (Qiagen, Hilden) with RNase-free DNase I treatment performed on RNA extraction spin column according to the manufacturer's instructions. RNA concentration was measured using the Nanodrop UV spectrophotometry platform (Nanodrop Technologies, USA). RNA integrity for all samples was assessed using Experion (software version 3.2, Bio-Rad).

All NB cell line lysates were allowed to thaw to room temperature prior to miRNA extraction. Consequently, all lysates were treated with the miRNeasy [Qiagen, Germany] miRNA extraction protocol, within the confines of a fume cupboard. The resultant 30 μL volume of extracted miRNA from each NB cell line lysate was quantified through utilisation of the Nanodrop UV spectrophotometry platform [Nanodrop Technologies, USA]. The extracted miRNA samples were then stored at − 80 °C until further use. The RNA quality was not tested following extraction, as previous experience from earlier studies repeatedly demonstrated that the RNA quality derived from NB cell lines was always of an excellent nature (with RIN values above 9.0), thus such a step was not performed.