Patient selection
A total of 27 men were included in this study; 7 controls, 13 patients with PD, and 7 with PCa. For the NGS experiments, we recruited 23 participants, including 7 controls with an age range of 54-87 years, 13 patients with PD with an age range of 50-88 years, and 3 patients with PCa aged 54, 71, and 72 years, respectively. Moreover, data deposited by Wong and colleagues [17] on a case history of 4 patients with PCa were analyzed.
Patients with PD and controls were recruited at the Oasi Research Institute-IRCCS, Troina (Italy), whereas patients with PCa were recruited at the Urology Unit, Cannizzaro Hospital, Catania (Italy). Family history was collected through a detailed interview of the wife or the first-degree relatives. The present and past clinical history of each patient was gathered and all available medical records (e.g., drug prescriptions, medical records, certificates) were carefully evaluated. All the diagnoses of PD were made by an experienced neurologist, according to the current PD diagnostic criteria [28]. PCa diagnoses were performed after radical prostatectomy and histological analysis. The diagnosis and grading of PCa were made according to the 2005 International Society of Urological Pathology (ISUP) Consensus Conference [29].
All patients and controls or their relatives gave their informed consent for study participation. The study was carried out in accordance with the Declaration of Helsinki of 1964 and its later amendments, and the Ethics Committee of the Oasi Research Institute–IRCCS, Troina (Italy) approved the protocol on June 03, 2017 (2017/05/31/CE-IRCCS-OASI/9).
RNA extraction
PBMCs separation was performed using Ficoll-Paque (Ficoll Plaque PLUS – GE Healthcare Life Sciences, Piscataway, USA) and the RNA was extracted using TRIzol reagent (TRIzol Reagent, Invitrogen Life Technologies, Carlsbad, CA, USA), according to the manufacturer’s instructions [30]. The RNA obtained was stored at -80o C.
RNA sequencing and data analysis
RNA sequencing was performed by Genomix4Life Srl (Baronissi, Italy). RNA concentration in each sample was assayed with an ND-2000c spectrophotometer (NanoDrop) and its quality was evaluated with the TapeStation 4200 (Agilent Technologies). Indexed libraries were prepared from 1 µg/ea purified RNA with TruSeq Stranded Total RNA (Illumina) Library Prep Kit according to the manufacturer’s instructions. Libraries were quantified using TapeStation 4200 (Agilent Technologies) and pooled such that each index-tagged sample was present in equimolar amounts, with a final concentration of the pooled samples of 2 nM. The pooled samples were subject to cluster generation and sequencing using an Illumina NextSeq 500 System (Illumina) in a 2x75 paired-end format. The raw sequence files generated (fastq files) underwent quality control analysis using FastQC (https://www.bioinformatics.babraham.ac.uk/projects/fastqc/). Subsequently, the quality-checked reads were trimmed with cutadapt v.1.10 and then aligned to the human genome (hg38 assembly) using STAR v.2.5.2 [31], with standard parameters. The read-count for the genes of interest was computed using feature Counts and normalized using negative binomial generalized linear models, considering all genes expressed in the samples, by Bioconductor DESeq2 package [31,32]. Transcripts showing fold-change ≤−1.35 or ≥1.35 (|FC| ≥1.35), with adjusted p-values ≤ 0.05 (padj) were considered as differentially expressed. Gene Ontology (GO) annotation analysis was performed using GO net web-application [33]. The sequencing data are available upon request, as they are partial data of a larger research project not yet completed.
RNA sequencing data from enriched prostate circulating tumor cells from clinical blood specimens
Raw data of enriched prostate circulating tumor cells (CTCs) from 12 (3 blood samples for each patient) clinical blood specimens were downloaded by NCBI GEO (accession number GSE104209) [17]. RNA sequencing data were analyzed as described above and compared to the in‑house control.