Luca Trentin

Background: Colorectal cancer is a worldwide leading cause of death accounting for high-rate mortality. Mutations in the epidermal growth factor receptor and RAS/MAPK pathways, as well as altered methylation genes profiles, have been described as molecular mechanisms promoting and sustaining tumour development and progression. Aberrant methylation is a well-known epigenetic mechanism involved in gene regulation; particularly several genes were reported as hypermethylated in CRC. Recently, it was shown that epigenetic alterations in genes such as neuropeptide y, proenkephalin and Wnt inhibitory factor 1 can be used as promising disease biomarkers. Almost all methods developed for the DNA methylation analysis combined next generation sequencing, conventional qRT-PCR or ddPCR with the prior DNA modification with sodium bisulfite. Methods and results: We implemented a ddPCR method to assess the methylation status of Wnt inhibitory factor 1 and neuropeptide y using the methylation sensitive restriction enzyme approach that does not impact on DNA quality and guarantees the discrimination of DNA methylation independent of bisulfite conversion. Conclusions: We showed that this method is robust and sensitive also allowing the monitoring of CRC disease progression when applied to circulating free DNA samples from liquid biopsies, proving to be a fast and easy to implement assay to be used for the monitoring of the methylation pattern of clinically relevant target genes.

The KMT2A/AFF1 rearrangement is associated with an unfavorable prognosis in infant acute lymphocytic leukemia (ALL). Discordant ALL in monozygotic twins is uncommon and represents an attractive resource to evaluate intrauterine environment–genetic interplay in ALL. Mutational and epigenetic profiles were characterized for a discordant KMT2A/AFF1-rearranged infant monozygotic twin pair and their parents, and they were compared to three independent KMT2A/AFF1-positive ALL infants, in which the DNA methylation and gene expression profiles were investigated. A de novo Q61H NRAS mutation was detected in the affected twin at diagnosis and backtracked in both twins at birth. The KMT2A/AFF1 rearrangement was absent at birth in both twins. Genetic analyses conducted at birth gave more insights into the timing of the mutation hit. We identified correlations between DNA methylation and gene expression changes for 32 genes in the three independent affected versus remitted patients. The strongest correlations were observed for the RAB32, PDK4, CXCL3, RANBP17, and MACROD2 genes. This epigenetic signature could be a putative target for the development of novel epigenetic-based therapies and could help in explaining the molecular mechanisms characterizing ALL infants with KMT2A/AFF1 fusions.

Direct antiviral agents (DAAs) have excellent efficacy against chronic hepatitis C virus (HCV) infection. Despite this strength, recent studies raised concerns about an unexpected hepatocellular carcinoma (HCC) occurrence rate after DAA therapy. In this exploratory case-control study, we evaluated the potential use of miRNAs as serum biomarkers for the detection of early HCC in DAA-treated patients. In the discovery phase, the circulating miRNome was assessed in 10 matched patients with (HCC+) or without HCC (HCC−) occurrence. Microarray analysis was performed before (T0) and after one month of the DAA therapy (T1). MiRNAs discriminating HCC+ and HCC− patients were validated in 60 samples by means of RT-qPCR. We estimated the time-averaged difference of a given miRNA between HCC+ and HCC− patients using a bootstrapped random-effect generalized least square regression model (RE-GLS). At T0, miR-1207-5p, miR-1275, miR-3197, miR-4443, miR-3178, miR-483-5p, miR-4706, miR-4793-3p and miR-1246 discriminated HCC+ from HCC− patients (p < 0.05). At T1, only miR-1180-3p, miR-1228-3p, miR-4329 and miR-4484 (p < 0.05) discriminated HCC+ from HCC− patients. The subsequent validation phase identified miR-3197 as changing with both disease and time. Our results suggest that patients might be already committed to HCC occurrence before DAA therapy. MiR-3197 shows some potential for the identification of patients at risk of HCC during DAA treatments.

Circular RNAs (circRNAs) are abundantly expressed in the haematopoietic compartment, but knowledge on their diversity among blood cell types is still limited. Nevertheless, emerging data indicate an array of circRNA functions exerted through interactions with other RNAs and proteins, by translation into peptides, and circRNA involvement as regulatory molecules in many biological processes and cancer mechanisms. Interestingly, the role of specific circRNAs in leukemogenesis has been disclosed by a few studies, mostly in acute myeloid leukemia. In this study, circRNA expression in B-cells, T-cells and monocytes of healthy subjects is described, including putative new circRNA genes. Expression comparison considered 6,228 circRNAs and highlighted cell population-specific expression and exon usage patterns. Differential expression has been confirmed by qRT-PCR for circRNAs specific of B-cells (circPAX5, circAFF3, circIL4R, and circSETBP1) or T-cells (circIKZF1, circTNIK, circTXK, and circFBXW7), and for circRNAs from intronic (circBCL2) and intergenic regions that were overexpressed in lymphocytes. Starting from this resource of circRNA expression in mature blood cell populations, targeted examination identified striking and generalized upregulated expression of circPAX5, circPVT1 and circHIPK3 in pediatric B-precursor acute lymphoblastic leukemia, and disclosed circRNAs with variable expression across cytogenetic subtypes.