Non-coding RNAs (ncRNAs) constitute a heterogeneous group of RNA molecules in terms of biogenesis, biological function as well as length and structure. These biological molecules have gained attention recently as a potentially crucial layer of tumor cell progression or regulation. ncRNAs are expressed in a broad spectrum of tumors, and they play an important role not only in maintaining but also in promoting cancer development and progression. Recent discoveries have revealed that ncRNAs may act as key signal transduction mediators in tumor signaling pathways by interacting with RNA or proteins. These results reinforce the hypothesis, that ncRNAs constitute therapeutic targets, and point out their clinical potential as stratification markers. The major purpose of this review is to mention the emergence of the importance of ncRNAs, as molecules which are correlated with cancer, and to discuss their clinical implicit as prognostic diagnostic indicators, biomarkers, and therapeutic targets.

MicroRNA-155-5p (miR-155-5p) is a proinflammatory, oncogenic miRNA, involved in various physiological processes, including hematopoiesis, immunity, inflammation, and cell lineage differentiation. It regulates important transcription factors, such as E2F2, hypoxia-inducible factor 1 (HIF1), and FOXO3. Recently, the dysregulation of miR-155-5p expression has been linked to chronic lymphocytic leukemia (CLL) pathogenesis. In this research study, we investigated the potential diagnostic and prognostic value of miR-155-5p in CLL. To achieve our goal, we isolated total RNA from peripheral blood mononuclear cells (PBMCs) collected from 88 CLL patients and 36 nonleukemic blood donors and performed polyadenylation of total RNA and reverse transcription. Next, we quantified miR-155-5p levels using an in-house-developed real-time quantitative PCR method, before proceeding to extensive biostatistical analysis. Thus, it appears that miR-155-5p is significantly overexpressed in PBMCs of CLL patients and can distinguish them from nonleukemic population. Kaplan-Meier OS analysis and bootstrap univariate Cox regression showed that high miR-155-5p expression predicts inferior OS for CLL patients (p < 0.001). Interestingly, miR-155-5p overexpression retains its unfavorable prognostic role in CLL patients stratified according to established prognostic factors [CD38 expression and mutational status of the immunoglobulin heavy chain variable region (IGHV)]. Thus, miR-155-5p appears as a promising, independent molecular biomarker of unfavorable prognosis in CLL.

MicroRNA-92a-3p (miR-92a-3p) is a member of the miR-17/92 cluster and the cancer-related miR-92 family. miR-92a-3p regulates important transcription factors such as hypoxia-inducible factor 1 (HIF1) and inhibits SOCS1 to enhance the anti-apoptotic STAT3/IL6 signaling route. In this study, we examined the putative prognostic value of miR-92a-3p in chronic lymphocytic leukemia (CLL). Total RNA, which was isolated from peripheral blood mononuclear cells (PBMCs) collected from 88 CLL patients and 36 non-leukemic blood donors, was polyadenylated and reverse-transcribed. miR-92a-3p expression was quantified using an in-house-developed real-time quantitative PCR assay. miR-92a-3p levels were significantly lower in PBMCs of CLL patients. Kaplan-Meier overall survival (OS) analysis and bootstrap univariate Cox regression showed that high miR-92a-3p expression predicts significantly prolonged OS for CLL patients. Interestingly, miR-92a-3p overexpression retains its favorable prognostic role in CLL patients of intermediate risk or stratified according to established prognostic factors. In conclusion, miR-92a-3p overexpression is a potential independent molecular biomarker of favorable prognosis in CLL.

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Overexpression of the cancer-associated miR-16 predicts poor DFS and OS of colorectal adenocarcinoma patients, independently of clinicopathological factors that are currently used for prognostic purposes.