RNA degradation and contamination was monitored on 1% agarose gels. According to the manufacturer's protocol, each tissue sample was washed three times using cold PBS and 1 ml TRIzol® reagent was added (Thermo Fisher Scientific, Inc.) to extract the RNA. The RNA concentration was measured using the Qubit® RNA assay kit in a Qubit® 2.0 Fluorometer (Thermo Fisher Scientific, Inc.). RNA integrity was verified using an RNA Nano 1000 assay kit for the Bioanalyzer 2100 system (Agilent Technologies, Inc.). The method for determining the levels of lncRNAs and miRNAs was the same as that used for mRNAs. For the quantification of circRNAs, exonuclease was used to exclude non-circRNAs. The RNA was divided into two copies. Linear RNA was digested with RNase R (cat. no. RNR07250; Epicentre; Illumina, Inc.) to leave only the circRNAs. The other half of the sample from the same RNA extraction was not treated with RNase R. The two samples of RNA were reverse transcribed according to a previous study (25 (link)). The sample treated with RNase R was used to examine the expression of circRNAs and the other sample that was not treated with RNase R was used to measure the expression of β-actin.