Central nervous system (CNS) malignancies include primary tumors that originate within the CNS as well as secondary tumors that develop as a result of metastatic spread. Circulating microRNAs (miRNAs) were found in almost all human body fluids including cerebrospinal fluid (CSF), and they seem to be highly stable and resistant to even extreme conditions. The overall aim of our study was to identify specific CSF miRNA patterns that could differentiate among brain tumors. These new biomarkers could potentially aid borderline or uncertain imaging results onto diagnosis of CNS malignancies, avoiding most invasive procedures such as stereotactic biopsy or biopsy. In total, 175 brain tumor patients (glioblastomas, low-grade gliomas, meningiomas and brain metastases), and 40 non-tumor patients with hydrocephalus as controls were included in this prospective monocentric study. Firstly, we performed high-throughput miRNA profiling (Illumina small RNA sequencing) on a discovery cohort of 70 patients and 19 controls and identified specific miRNA signatures of all brain tumor types tested. Secondly, validation of 9 candidate miRNAs was carried out on an independent cohort of 105 brain tumor patients and 21 controls using qRT-PCR. Based on the successful results of validation and various combination patterns of only 5 miRNA levels (miR-30e, miR-140, let-7b, mR-10a and miR-21-3p) we proposed CSF-diagnostic scores for each tumor type which enabled to distinguish them from healthy donors and other tumor types tested. In addition to this primary diagnostic tool, we described the prognostic potential of the combination of miR-10b and miR-196b levels in CSF of glioblastoma patients. In conclusion, we performed the largest study so far focused on CSF miRNA profiling in patients with brain tumors, and we believe that this new class of biomarkers have a strong potential as a diagnostic and prognostic tool in these patients.

Small noncoding RNAs play an important role in various disease states, including cancer. PIWI proteins, a subfamily of Argonaute proteins, and PIWI-interacting RNAs (piRNAs) were originally described as germline-specific molecules that inhibit the deleterious activity of transposable elements. However, several studies have suggested a role for the piRNA-PIWI axis in somatic cells, including somatic stem cells. Dysregulated expression of piRNAs and PIWI proteins in human tumors implies that, analogously to their roles in undifferentiated cells under physiological conditions, these molecules may be important for cancer stem cells and thus contribute to cancer progression. We provide an overview of piRNA biogenesis and critically review the evidence for the role of piRNA-PIWI axis in cancer stem cells. In addition, we examine the potential of piRNAs and PIWI proteins to become biomarkers in cancer.

Resistance to the ionizing radiation is a current problem in the treatment and clinical management of various cancers including head and neck cancer. There are several biological and molecular mechanisms described to be responsible for resistance of the tumors to radiotherapy. Among them, the main mechanisms include alterations in intracellular pathways involved in DNA damage and repair, apoptosis, proliferation, and angiogenesis. It has been found that regulation of these complex processes is often controlled by microRNAs. MicroRNAs are short endogenous RNA molecules that posttranscriptionally modulate gene expression and their deregulated expression has been observed in many tumors including head and neck cancer. Specific expression patterns of microRNAs have also been shown to predict prognosis and therapeutic response in head and neck cancer. Therefore, microRNAs present promising biomarkers and therapeutic targets that might overcome resistance to radiation and improve prognosis of head and neck cancer patients. In this review, we summarize the current knowledge of the functional role of microRNAs in radioresistance of cancer with special focus on head and neck cancer.

Brain metastases are the most frequent intracranial tumors in adults and the cause of death in almost one-fourth of cases. The incidence of brain metastases is steadily increasing. The main reason for this increase could be the introduction of new and more efficient therapeutic strategies that lead to longer survival but, at the same time, cause a higher risk of brain parenchyma infiltration. In addition, the advances in imaging methodology, which provide earlier identification of brain metastases, may also be a reason for the higher recorded number of patients with these tumors. Metastasis is a complex biological process that is still largely unexplored, influenced by many factors and involving many molecules. A deeper understanding of the process will allow the discovery of more effective diagnostic and therapeutic approaches that could improve the quality and length of patient survival. Recent studies have shown that microRNAs (miRNAs) are essential molecules that are involved in specific steps of the metastatic cascade. MiRNAs are endogenously expressed small non-coding RNAs that act as post-transcriptional regulators of gene expression and thus regulate most cellular processes. The dysregulation of these molecules has been implicated in many cancers, including brain metastases. Therefore, miRNAs represent promising diagnostic molecules and therapeutic targets in brain metastases. This review summarizes the current knowledge on the importance of miRNAs in brain metastasis, focusing on their involvement in the metastatic cascade and their potential clinical implications.

Background: Identifying novel diagnostic and prognostic biomarkers for pediatric inflammatory bowel diseases (PIBD), including Crohn’s disease (pCD) and ulcerative colitis (pUC), is essential for enhancing treatment outcomes. MicroRNAs (miRNAs) have been recognized for their broader relevance in PIBD pathogenesis. This study investigates their diagnostic potential and clinical utility in PIBD. Methods: This prospective, monocentric study, with retrospective validation, involved 119 PIBD patients (58 pCD, 61 pUC) and 39 non-IBD controls. Small RNA next-generation sequencing was performed on fresh-frozen gut biopsies, targeting histopathologically confirmed inflamed areas. Twenty-five dysregulated miRNA candidates were validated via RT-qPCR in formalin-fixed, paraffin-embedded gut biopsies. Logistic regression was used to establish diagnostic and prognostic miRNA expression signatures. Results: A diagnostic signature of 5 miRNAs (miR-223-3p, miR-34a-5p, miR-194-5p, miR-215-5p, miR-338-3p) distinguished pCD from non-IBD with 96.49% accuracy. Two miRNAs (miR-223-3p, miR-194-5p) differentiated pUC from non-IBD with 100% accuracy, and miR-215-5p distinguished pCD from pUC specimens with 83.54% accuracy. For treatment-naïve pCD patients, 7 miRNAs predicted residual disease activity at 3 months with 100% accuracy. Additionally, a distinct signature predicted the risk of relapse within 12 months with an accuracy of 84.21%. Conclusions: In this study, we have established tissue miRNA expression signatures with significant diagnostic and prognostic potential for use in PIBD. These findings aid in stratifying disease severity and risk, paving the way for more precise and personalized management of pediatric IBD.

BACKGROUND AND OBJECTIVES: Meningioma, the most common primary intracranial tumor, presents challenges in surgical treatment because of varying tissue stiffness. This study explores the molecular background of meningioma stiffness, a critical factor in surgical planning and prognosis, focusing on the utility of microRNAs (miRNAs) as diagnostic biomarkers of tissue stiffness. METHODS: Patients with meningiomas treated surgically at the University Hospital Brno were included in this study. Total RNA, isolated from tumor tissue samples, underwent quality control and small RNA sequencing to analyze miRNA expression. Differentially expressed miRNAs were identified, and their association with tumor stiffness was assessed. RESULTS: This study identified specific miRNAs differentially expressed in meningiomas with different stiffness levels. Key miRNAs, such as miR-31-5p and miR-34b-5p, showed significant upregulation in stiffer meningiomas. These findings were validated using reverse transcription-quantitative polymerase chain reaction, revealing a potential link between miRNA expression and tumor consistency. The expression of miR-31-5p was most notably associated with the stiffness of the tumor tissue (sensitivity = 71% and specificity = 83%). CONCLUSION: This research highlights the potential of miRNAs as biomarkers for determining meningioma tissue stiffness. Identifying specific miRNAs associated with tumor consistency could improve preoperative planning and patient prognosis. These findings pave the way for further exploration of miRNAs in the clinical assessment of meningiomas.