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Objective: 3′ tRNA‐derived fragments (3′ tRFs) are important epigenetic regulators in normal and pathological conditions. In this study, we aimed to explore the potential value of a 3′ tRF as a prognostic and/or screening biomarker for B‐cell chronic lymphocytic leukemia (B‐CLL). Methods: Publicly available next‐generation sequencing data from 20 B‐CLL cases were analyzed, followed by prediction of targets of the most abundantly and ubiquitously expressed 3′ tRFs, leading to selection of tRF‐LeuAAG/TAG. PBMCs were isolated from blood samples of 91 B‐CLL patients and 43 non‐leukemic donors, followed by total RNA extraction, in‐vitro polyadenylation, and first‐strand cDNA synthesis. Next, a real‐time quantitative PCR (qPCR) assay was developed for the accurate quantification of tRF‐LeuAAG/TAG and applied in all samples, prior to biostatistical analysis. Results: High tRF‐LeuAAG/TAG levels are associated with inferior overall survival (OS) of B‐CLL patients. The unfavorable significance of tRF‐LeuAAG/TAG was independent of established prognostic factors in B‐CLL. Stratified Kaplan‐Meier OS analysis uncovered the unfavorable prognostic role of high tRF‐LeuAAG/TAG levels for patients in Binet A or Rai I stage, negative CD38 expression, mutated, or unmutated IGHV genomic locus. Conclusion: Our approach revealed the independent prognostic value of a particular 3′ tRF, derived from tRNALeuAAG and tRNALeuTAG (tRF‐LeuAAG/TAG) in B‐CLL. [ABSTRACT FROM AUTHOR]

Simple Summary: The involvement of miRNAs in physiological cellular processes has been well documented. The development of B cells, which is dictated by a miRNA-transcription factor regulatory network, suggests a typical process partly orchestrated by miRNAs. Besides their contribution in normal hematopoiesis, miRNAs have been severally reported to be implicated in hematological malignancies, a typical example of which is B-cell chronic lymphocytic leukemia (B-CLL). Numerous studies have attempted to highlight the regulatory role of miRNAs in B-CLL or establish some of them as molecular biomarkers or therapeutic targets. Thus, a critical review summarizing the current knowledge concerning the multifaceted role of miRNAs in normal B-cell development and B-CLL progression, prognosis, and therapy, is urgent. Moreover, this review aims to highlight important miRNAs in both normal B-cell development and B-CLL and discuss future perspectives concerning their regulatory potential and establishment in clinical practice. MicroRNAs (miRNAs) represent a class of small non-coding RNAs bearing regulatory potency. The implication of miRNAs in physiological cellular processes has been well documented so far. A typical process orchestrated by miRNAs is the normal B-cell development. A stage-specific expression pattern of miRNAs has been reported in the developmental procedure, as well as interactions with transcription factors that dictate B-cell development. Besides their involvement in normal hematopoiesis, miRNAs are severally implicated in hematological malignancies, a typical paradigm of which is B-cell chronic lymphocytic leukemia (B-CLL). B-CLL is a highly heterogeneous disease characterized by the accumulation of abnormal B cells in blood, bone marrow, lymph nodes, and spleen. Therefore, timely, specific, and sensitive assessment of the malignancy is vital. Several studies have attempted to highlight the remarkable significance of miRNAs as regulators of gene expression, biomarkers for diagnosis, prognosis, progression, and therapy response prediction, as well as molecules with potential therapeutic utility. This review seeks to outline the linkage between miRNA function in normal and malignant hematopoiesis by demonstrating the main benchmarks of the implication of miRNAs in the regulation of normal B-cell development, and to summarize the key findings about their value as regulators, biomarkers, or therapeutic targets in B-CLL. [ABSTRACT FROM AUTHOR]

Circular RNAs (circRNAs) constitute a type of RNA formed through back-splicing. In breast cancer, circRNAs are implicated in tumor onset and progression. Although histone methylation by PRMT1 is largely involved in breast cancer development and metastasis, the effect of circular transcripts deriving from this gene has not been examined. In this study, total RNA was extracted from four breast cancer cell lines and reversely transcribed using random hexamer primers. Next, first- and second-round PCRs were performed using gene-specific divergent primers. Sanger sequencing followed for the determination of the sequence of each novel PRMT1 circRNA. Lastly, bioinformatics analysis was conducted to predict the functions of the novel circRNAs. In total, nine novel circRNAs were identified, comprising both complete and truncated exons of the PRMT1 gene. Interestingly, we demonstrated that the back-splice junctions consist of novel splice sites of the PRMT1 exons. Moreover, the circRNA expression pattern differed among these four breast cancer cell lines. All the novel circRNAs are predicted to act as miRNA and/or protein sponges, while five circRNAs also possess an open reading frame. In summary, we described the complete sequence of nine novel circRNAs of the PRMT1 gene, comprising distinct back-splice junctions and probably having different molecular properties. [ABSTRACT FROM AUTHOR]

• An innovative qPCR method for quantification of i-tRF-GlyCCC levels was developed. • High i-tRF-GlyCCC expression predicts poor overall survival in CLL patients. • Prognostic significance of i-tRF-GlyCCC is independent of other prognostic factors. • i-tRF-GlyCCC is an unfavorable prognosticator in distinct subgroups of CLL patients Chronic lymphocytic leukemia (CLL) is one of the most common types of leukemia in adults. Several studies have identified various prognostic biomarkers in CLL. In this study, we investigated the potential value of an internal fragment of the tRNAs bearing the Glycine anticodon CCC (i-tRF-GlyCCC), which is a small non-coding RNA, as a prognostic and screening biomarker in CLL. For this purpose, blood samples were collected from 90 CLL patients and 43 non-leukemic blood donors. Peripheral blood mononuclear cells (PBMCs) were isolated, total RNA was extracted and in-vitro polyadenylated, and first-strand cDNA was synthesized using an oligo-dT–adaptor primer. A real-time quantitative PCR assay was developed and applied for the quantification of i-tRF-GlyCCC in our samples. The biostatistical analysis revealed that i-tRF-GlyCCC levels are significantly lower in PBMCs of CLL patients, compared to PBMCs of non-leukemic controls, and that i-tRF-GlyCCC could be considered as a screening biomarker. Kaplan-Meier overall survival (OS) analysis revealed reduced OS for CLL patients with positive i-tRF-GlyCCC expression (P = 0.001). Multivariate Cox regression confirmed its independent unfavorable prognostic power with regard to OS. In conclusion, i-tRF-GlyCCC may constitute a promising molecular biomarker in CLL, for screening and prognostic purposes. [ABSTRACT FROM AUTHOR]