Identification of Two Novel Circular RNAs Deriving from BCL2L12 and Investigation of Their Potential Value as a Molecular Signature in Colorectal Cancer

Abstract

The utility of circular RNAs (circRNAs) as molecular biomarkers has recently emerged. However, only a handful of them have already been studied in colorectal cancer (CRC). The purpose of this study was to identify new circRNAs deriving from BCL2L12, a member of the BCL2 apoptosis-related family, and investigate their potential as biomarkers in CRC. Total RNA extracts from CRC cell lines and tissue samples were reversely transcribed. By combining PCR with divergent primers and nested PCR followed by Sanger sequencing, we were able to discover two BCL2L12 circRNAs. Subsequently, bioinformatical tools were used to predict the interactions of these circRNAs with microRNAs (miRNAs) and RNA-binding proteins (RBPs). Following a PCR-based pre-amplification, real-time qPCR was carried out for the quantification of each circRNA in CRC samples and cell lines. Biostatistical analysis was used to assess their potential prognostic value in CRC. Both novel BCL2L12 circRNAs likely interact with particular miRNAs and RBPs. Interestingly, circ-BCL2L12-2 expression is inversely associated with TNM stage, while circ-BCL2L12-1 overexpression is associated with shorter overall survival in CRC, particularly among TNM stage II patients. Overall, we identified two novel BCL2L12 circRNAs, one of which can further stratify TNM stage II patients into two subgroups with substantially distinct prognosis.

Circular RNAs: Emerging Regulators of the Major Signaling Pathways Involved in Cancer Progression

“…Numerous evidence supports that circRNAs are correlated with the progression of human diseases through their interaction with signaling pathways, and their biomarker potential has been proved by multiple studies [ 16 , 17 ]. In particular, circRNAs are generally proven to intervene in tumor stemness, migration, invasion, and metastasis [ 18 ]; for instance, they are involved in the activation of the epithelial–mesenchymal transition (EMT) process via the WNT/β-catenin signaling pathway, affecting directly the tumor progression [ 19 , 20 ].…”

Multiple Myeloma Bone Disease: Implication of MicroRNAs in Its Molecular Background

“…Regarding malignancy, miRNA-targeted therapy consists of inhibition of oncomiRs and upregulation of tumor-suppressor miRNAs. Inhibition of oncogenic miRNAs can be achieved by antagomiRs, which are antisense miRNA molecules, or by miRNA-sponges (e.g., circular RNAs [ 130 ]) that are molecules that act as competing endogenous RNAs and thus are able to bind the miRNA and prevent it from binding to the target mRNA. Tumor-suppressor miRNAs can be therapeutically replaced by using viral and non-viral vectors and miRNA mimics [ 21 ].…”

Oncogenic Functions and Clinical Significance of Circular RNAs in Colorectal Cancer

“…However, similar to miRNA sponging, the low circRNA abundance may be challenging for them to affect protein binding significantly [ 70 ]. Regarding colorectal cancer, Karousi et al, 2020 [ 71 ] reported two novel circRNAs for both of which various protein-binding sites were detected, and many RBPs were predicted in silico to bind them. Among selected RBPs with more than five binding sites were serine and arginine-rich splicing factors (SRSF), FUS RNA-binding protein, heterogeneous nuclear ribonucleoprotein H1 (HNRNPH1), and others.…”