miR-125b and miR-532-3p predict the efficiency of rituximab-mediated lymphodepletion in chronic lymphocytic leukemia patients. A French Innovative Leukemia Organization study

Screening and molecular mechanism research on bile microRNAs associated with chemotherapy efficacy in perihilar cholangiocarcinoma

The efficacy of hepatic arterial infusion chemotherapy (HAIC) with oxaliplatin (OXA) and 5-fluorouracil (5-Fu) for treating advanced perihilar cholangiocarcinoma (pCCA) has been demonstrated, yet the survival benefits of HAIC for pCCA patients vary. Here, we aimed to screen out HAIC resistance-related bile microRNAs (miRNAs) and explore the functions of specific bile miRNAs in pCCA based on high-throughput sequencing. Levels of bile miR-532-3p, miR-1250-5p, and miR-4772-5p were related to the survival of advanced pCCA patients after HAIC. However, only overexpression of miR-532-3p promoted OXA/5-Fu resistance, and downregulation of its expression improved sensitivity to OXA/5-Fu. Mechanistic investigations revealed secreted protein acidic and rich in cysteine (SPARC) as the direct target of miR-532-3p. Our study reveals that bile miR-532-3p, miR-1250-5p, and miR-4772-5p may serve as survival biomarkers in advanced pCCA patients after HAIC and that bile miR-532-3p promotes resistance to HAIC with OXA and 5-Fu via negatively regulating SPARC expression.

Dysregulated MicroRNAs in Chronic Lymphocytic Leukemia

MiRNAs are a class of non-coding RNAs acting as gene expression regulators by modulating the lifespan of messenger RNA. Commonly referred to as the most frequent leukemia in the Western world, chronic lymphocytic leukemia (CLL) is a lymphoproliferative malignancy characterized by clonal expansion of CD19, CD23, and CD5-positive mature B-cells. While this pathology is regarded as less aggressive and has a variety of treatment options, the cause of its clinical heterogeneity is not yet understood. Moreover, the prognostic markers and treatment recommendations based on predictive markers are limited. This review aims to investigate some miRNAs that are dysregulated and possibly involved in CLL pathogenesis as a starting point for the proposal of new prognostic and predictive markers and, as more agents targeting miRNA expression become available, their potential role as therapeutic targets.

miRNA Biology in Chronic Lymphocytic Leukemia

microRNAs (miRNAs) are a class of small non-coding RNAs that play a crucial regulatory role in fundamental biological processes and have been implicated in various diseases, including cancer. The first evidence of the cancer-related function of miRNAs was discovered in chronic lymphocytic leukemia (CLL) in the early 2000s. Alterations in miRNA expression have since been shown to strongly influence the clinical course, prognosis, and response to treatment in patients with CLL. Therefore, the identification of specific miRNA alterations not only enhances our understanding of the molecular mechanisms underlying CLL but also holds promise for the development of novel diagnostic and therapeutic strategies. This review aims to provide a comprehensive summary of the current knowledge and recent insights into miRNA dysregulation in CLL, emphasizing its pivotal roles in disease progression, including the development of the lethal Richter syndrome, and to provide an update on the latest translational research in this field.

miRNAs as cornerstones in chronic lymphocytic leukemia pathogenesis and therapeutic resistance- An emphasis on the interaction of signaling pathways

Chronic lymphocytic leukemia (CLL) accounts for the vast majority of cases of leukemia. Patients of advanced age are more likely to develop the condition, which has a highly varied clinical course. Consideration of illness features and preceding treatment sequence, as well as patient preferences and comorbidities, is necessary for selecting the appropriate treatment for the appropriate patient. Therefore, there is an urgent need for novel biomarkers with high sensitivity and specificity to detect CLL early, monitor CLL patients, select the treatment responders, and reduce ineffective treatment, unwanted side effects, and unnecessary expenses. In both homeostasis and illness, microRNAs (miRNAs/miRs) play a vital role as master regulators of gene expression and, by extension, protein expression. MiRNAs typically reduce the stability of mRNAs, including those encoding genes involved in tumorigenesis processes as cell cycle regulation, inflammation, stress response, angiogenesis, differentiation, apoptosis, and invasion. Due to their unique properties, miRNAs are rapidly being exploited as accurate biomarkers for illness detection, and medicines based on miRNA targets are finding widespread application in clinical practice. Accordingly, the current review serves as a quick primer on CLL and the biogenesis of miRNAs. In addition to providing a brief overview of the miRNAs whose function in the progression of CLL has been established by recent in vitro or in vivo research through articulating the influence of these miRNAs on a wide variety of cellular functions, including increased proliferative potential; support for angiogenesis; cell cycle aberration; evasion of apoptosis; promotion of metastasis; and reduced sensitivity to specific treatments.

miRNA profile at diagnosis predicts treatment outcome in patients with B-chronic lymphocytic leukemia: A FILO study

During many years, chemo-immunotherapy fludarabine-cyclophosphamide-rituximab (FCR) was the gold standard for first line treatment of medically fit patients with symptomatic B-chronic lymphocytic leukemia (CLL). Over the last decade, targeted biotherapies have revolutionized the treatment of B-CLL patients and almost entirely supplanted FCR. However, no biomarker still exists to predict the complete remission (CR) with undetectable minimal residual disease (uMRD) in bone marrow (BM), which remains the best predictive factor for survival. MicroRNAs represent a class of molecular biomarkers which expression is altered in B-CLL. Our study aimed at identifying before treatment blood miRNAs that predict treatment outcome in previously untreated B-CLL patients (NCT 01370772, https://clinicaltrials.gov/ct2/show/NCT01370772). Using hierarchical clustering of miRNA expression profiles discriminating 8 patients who achieved CR with BM uMRD from 8 patients who did not achieve CR and displayed detectable BM MRD, we identified 25 miRNAs differentially expressed before treatment. The expression of 11 miRNAs was further validated on a larger cohort (n=123). Based on the dosage of 5 miRNAs at diagnosis, a decision tree was constructed to predict treatment outcome. We identified 6 groups of patients with a distinct probability of being CR with BM uMRD to FCR treatment, ranging from 72% (miR-125b, miR-15b and miR-181c high) to 4% (miR-125b and miR-193b low). None of the patients displaying high expression levels of miR-125b, miR-15b and miR-181c relapsed during study follow-up. In contrast, patients with low miR-15b and high miR-412, or with low miR-125b and miR-193b, demonstrated significant low PFS. RNA sequencing of blood at diagnosis identified that patients relapsing after treatment are characterized by significant enrichment of gene signatures related to cell cycle, MYC target genes, metabolism and translation regulation. Conversely, patients achieving CR with BM uMRD displayed significant enrichment in genes related to communication between CLL cells and the microenvironment, immune system activation and upregulation of polycomb PRC2 complex target genes. Our results suggest that blood miRNAs are potent predictive biomarkers for FCR treatment efficacy and might be implicated in the FCR efficacy in B-CLL patients, providing new insight into unmet need for the treatment of B-CLL patients and identifying pathways predictive of patients’ remission.

miRNAs in Lymphocytic Leukaemias-The miRror of Drug Resistance

Refractory disease and relapse remain the main causes of cancer therapy failure. Refined risk stratification, treatment regimens and improved early diagnosis and detection of minimal residual disease have increased cure rates in malignancies like childhood acute lymphoblastic leukaemia (ALL) to 90%. Nevertheless, overall survival in the context of drug resistance remains poor. The regulatory role of micro RNAs (miRNAs) in cell differentiation, homeostasis and tumorigenesis has been under extensive investigation in different cancers. There is accumulating data demonstrating the significance of miRNAs for therapy outcomes in lymphoid malignancies and some direct demonstrations of the interplay between these small molecules and drug response. Here, we summarise miRNAs' impact on chemotherapy resistance in adult and paediatric ALL and chronic lymphocytic leukaemia (CLL). The main focus of this review is on the modulation of particular signaling pathways like PI3K-AKT, transcription factors such as NF-κB, and apoptotic mediators, all of which are bona fide and pivotal elements orchestrating the survival of malignant lymphocytic cells. Finally, we discuss the attractive strategy of using mimics, antimiRs and other molecular approaches pointing at miRNAs as promising therapeutic targets. Such novel strategies to circumvent ALL and CLL resistance networks may potentially improve patients' responses and survival rates.

Bioinformatic Analysis Identified Potentially Prognostic Long Noncoding RNAs and MicroRNAs for Gastric Cancer

Gastric cancer (GC) is the fifth most common malignant tumor in the world. The present study was performed to discover the potential diagnostic and therapeutic long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) of GC. Data used in this study to identify differentially expressed lncRNAs (DElncRNAs) and miRNAs (DEmiRNAs) were obtained from 187 GC tissues and 32 adjacent nontumor tissues. The total clinical data on GC included 187 cases. The above data were from the TCGA database. RStudio/Bioconductor software was used to conduct univariate analysis, the least absolute shrinkage and selection operator (LASSO) Cox, and multivariate Cox proportional risk regression for the DElncRNAs and DEmiRNAs. Clinical information was analyzed through univariate and multivariate Cox analysis. Results: five lncRNAs (AC007785.3, AC079385.3, LINC00392, LINC01729, and U95743.1) and two miRNAs (hsa-miR-3174, hsa-miR-605) were proven to be independent prognostic indicators of GC. Results of the Kaplan-Meier survival analysis showed that AC007785.3, AC079385.3, LINC01729, miR-3174, and miR-605 were significantly correlated with OS of GC. The target genes of AC079385.3, miR-3174, and miR-605 were obtained and clustered mainly on MAPK and cGMP-PKG signaling pathways. The clinical data showed that age and clinicopathologic stage were correlated with the prognosis of GC. Furthermore, AC007785.3 was associated with metastasis of GC, and miR-3174 was associated with the primary tumor condition of GC. We identified three lncRNAs (AC007785.3, AC079385.3, LINC01729), two miRNAs (miR-3174, miR-605), and clinical factors related to the pathogenesis and prognosis of GC. Our predicted results provide a possible entry point for the study of prognostic markers for GC.

The regulation and function of CD20: an "enigma" of B-cell biology and targeted therapy

The introduction of anti-CD20 monoclonal antibodies such as rituximab, ofatumumab, or obinutuzumab improved the therapy of B-cell malignancies even though the precise physiological role and regulation of CD20 remains unclear. Furthermore, CD20 expression is highly variable between different B-cell malignancies, patients with the same malignancy, and even between intraclonal subpopulations in an individual patient. Several epigenetic (EZH2, HDAC1/2, HDAC1/4, HDAC6, complex Sin3A-HDAC1) and transcription factors (USF, OCT1/2, PU.1, PiP, ELK1, ETS1, SP1, NFκB, FOXO1, CREM, SMAD2/3) regulating CD20 expression (encoded by MS4A1) have been characterized. CD20 is induced in the context of microenvironmental interactions by CXCR4/SDF1 (CXCL12) chemokine signaling and the molecular function of CD20 has been linked to the signaling propensity of B-cell receptor (BCR). CD20 has also been shown to interact with multiple other surface proteins on B cells (such as CD40, MHCII, CD53, CD81, CD82, and CBP). Current efforts to combine anti-CD20 monoclonal antibodies with BCR signaling inhibitors targeting BTK or PI3K (ibrutinib, acalabrutinib, idelalisib, duvelisib) or BH3-mimetics (venetoclax) lead to the necessity to better understand both the mechanisms of regulation and the biological functions of CD20. This is underscored by the observation that CD20 is decreased in response to the "BCR inhibitor" ibrutinib which largely prevents its successful combination with rituximab. Several small molecules (such as histone deacetylase inhibitors, DNA methyl-transferase inhibitors, aurora kinase A/B inhibitors, farnesyltransferase inhibitors, FOXO1 inhibitors, and bryostatin-1) are being tested to upregulate cell-surface CD20 levels and increase the efficacy of anti-CD20 monoclonal antibodies. Herein, we review the current understanding of CD20 function, and the mechanisms of its regulation in normal and malignant B cells, highlighting the therapeutic implications.

MicroRNAs: Tiny Regulators of Gene Expression with Pivotal Roles in Normal B-Cell Development and B-Cell Chronic Lymphocytic Leukemia

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.

Abstract

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.

Plasma exosome-derived microRNA-532 as a novel predictor for acute myeloid leukemia

BACKGROUND

The interest in plasma biomarkers has increased recently. Plasma exosome-derived microRNA-532 is aberrantly expressed in a variety of human cancers and has the prognostic value in many solid tumors. However, the prognostic impact of the expression value on AML remains unclear.

OBJECTIVE

The aim of this study is to investigate the prognostic value of exosome-derived microRNA-532 in AML patients.

METHODS

We performed the real-time PCR to quantify exosome-derived microRNA-532 in plasma of 198 AML patients. To assess the prognostic value, we performed Cox regression analyses in the context of well-established clinical and molecular markers. Cellular metabolic profile was conducted to help us understand the biological insight of its expression.

RESULTS

The expression level was not associated with white blood cell counts, age, FAB subtypes, cytogenetic risk groups and genes of FLT3-ITD, NPM1, CEBPA and DNMT3A mutations. Interestingly, high expressers had a favorable overall survival in the univariate analysis. This prognostic value was testified in the multivariate analysis. Moreover, up-regulation of miR-532 was negatively associated with cellular energy like fructose and glutamine.

CONCLUSION

We found plasma exosome-derived microRNA-532 can be used as a novel survival predictor for acute myeloid leukemia.

Non-Coding RNAs as Cancer Hallmarks in Chronic Lymphocytic Leukemia

The discovery of non-coding RNAs (ncRNAs) and their role in tumor onset and progression has revolutionized the way scientists and clinicians study cancers. This discovery opened new layers of complexity in understanding the fine-tuned regulation of cellular processes leading to cancer. NcRNAs represent a heterogeneous group of transcripts, ranging from a few base pairs to several kilobases, that are able to regulate gene networks and intracellular pathways by interacting with DNA, transcripts or proteins. Deregulation of ncRNAs impinge on several cellular responses and can play a major role in each single hallmark of cancer. This review will focus on the most important short and long non-coding RNAs in chronic lymphocytic leukemia (CLL), highlighting their implications as potential biomarkers and therapeutic targets as they relate to the well-established hallmarks of cancer. The key molecular events in the onset of CLL will be contextualized, taking into account the role of the "dark matter" of the genome.

MicroRNA-532-3p Regulates Pro-Inflammatory Human THP-1 Macrophages by Targeting ASK1/p38 MAPK Pathway

Inflammation is a complex biological process which alters the normal physiological function of the immune system resulting in an abnormal microenvironment that leads to several clinical complications. The process of inflammation is mediated through various intracellular signaling factors inside the cells. Apoptosis signal-regulating kinase 1 (ASK1) is an inflammation-derived kinase that controls the activation of other family of kinases such as p38 mitogen-activated protein kinases (p38 MAPKs), which mediates various the inflammatory processes. In this study, we cultured THP-1 macrophage cells to undergo inflammatory proliferation with LPS (1 μg/ml) and TNFα (10 ng/ml) stimulation. Initial in silico analysis was utilized to predict novel microRNAs (miRNAs) that target ASK1 signaling and its expression levels in LPS and TNFα stimulated THP-1 cells were estimated. Among the miRNAs, miR-532-3p showcased the highest binding affinity towards ASK1 kinase. We witnessed that transient transfection of miR-532-3p diminished the levels of ASK1 and downstream phosphorylation/translocation of p38 MAPK. Furthermore, direct targeting of ASK1 resulted in regulation of uncontrolled release of cytokines (TNFα, IL-6, and IL-23) and chemokines (GM-CSF and MIP-2α). Overall, we suggest that miR-532-3p attenuates the pro-inflammatory nature of macrophages by targeting ASK1/p38 MAPK signaling pathway and can be used as a molecular intervention for treating inflammatory diseases.

miR-532-3p Inhibits Proliferation and Promotes Apoptosis of Lymphoma Cells by Targeting β-Catenin

Background: Dysregulated expression of miR-532-3p has been observed in several types of cancer and plays a key role in tumor progression and metastasis. In this study, we analyzed the role and molecular mechanism of miR-532-3p in lymphoma progression.

Methods: The expression of miR-532-3p in lymphoma sample tissues was analyzed using the GEO database and in cell lines by quantitative reverse transcription (qRT)-PCR. The functions of miR-532-3p in lymphoma cell proliferation and apoptosis were analyzed by CCK-8 assay and Annexin V-FITC/propidium iodide staining, respectively. In vivo, the tumor weight and volume were measured. The target gene of miR-532-3p was predicted using miRanda software, and then luciferase, qRT-PCR, and western blot assays were performed to verify that β-catenin was the downstream target gene of miR-532-3p.

Results: miR-532-3p was decreased in lymphoma tissues and cell lines. In vitro and in vivo experiments showed that overexpression of miR-532-3p inhibited lymphoma cell proliferation and promoted apoptosis. Mechanistic studies demonstrated that β-catenin was a functional target gene of miR-532-3p. Furthermore, we found that overexpression of β-catenin reversed the tumor-suppression activities caused by overexpression of miR-532-3p in lymphoma proliferation and apoptosis.

Conclusion: This study demonstrates that miR-532-3p functions as a tumor inhibitor in lymphoma progression by targeting β-catenin, suggesting miR-532-3p/β-catenin as a new diagnosis marker or potential therapeutic target in lymphoma.

Inflammation-dependent downregulation of miR-532-3p mediates apoptotic signaling in human sarcopenia through targeting BAK1

Inflammation and apoptosis are considered as two major pathological causes of human sarcopenia. The current understanding based on different models recognizes that apoptosis does not trigger inflammation, while emerging evidence indicates that inflammation can induce apoptosis. Here, we provide solid evidence to suggest that the inflammation-dependent downregulation of miR-532 causes apoptosis through targeting a proapoptotic gene BAK1 (BCL2 antagonist/killer 1). To identify miRNAs and genes that are aberrantly expressed in the muscle tissues of sarcopenia patients, we conducted two independent microarray analyses. In total, we identified 53 miRNAs and 69 genes with differential expression levels. Of these aberrantly expressed miRNAs, miR-532-3p showed the most obvious changes in sarcopenia tissues, and more importantly, it can be repressed by the well-known inflammatory inducer lipopolysaccharide (LPS) in vitro. According to gene-based microarray results and the predicted targets of miR-532-3p, we presumed that BAK1 was a putative target of miR-532-3p. Further in vitro and in vivo analyses verified that miR-532-3p could directly bind to the three prime untranslated region (3'-UTR) of BAK1 through the seed sequence CUCCCAC. In addition, we found that NFKB1 (also known as p50), a subunit of the transcription factor NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells), could specifically bind to the promoter region of miR-532-3p and repress its expression. Further analysis revealed that the activation of TLR4 (Toll-like receptor 4) signaling led to the translocation of p50 from the cytoplasm to the nucleus, where it repressed miR-532-3p expression and thus led to an increase of BAK1. The accumulated BAK1 activated its downstream apoptotic signaling pathways and resulted in apoptosis, eventually causing the pathogenesis underlying sarcopenia. Overall, our results uncovered a new mechanism by which the inflammation-dependent downregulation of miR-532-3p contributed to the pathogenesis of sarcopenia through mediating BAK1 expression.

MicroRNAs, Regulatory Messengers Inside and Outside Cancer Cells

MicroRNAs (miRNAs) are a class of short non-coding RNAs (ncRNAs) with typical sequence lengths of 19-25 nucleotides and extraordinary abilities to regulate gene expression. Because miRNAs regulate multiple important biological functions of the cell (proliferation, migration, invasion, apoptosis, differentiation, and drug resistance), their expression is highly controlled. Genetic and epigenetic alterations frequently found in cancer cells can cause aberrant expression of miRNAs and, consequently, of their target genes. The tumor microenvironment can also affect miRNA expression through soluble factors (e.g., cytokines and growth factors) secreted by either tumor cells or non-tumor cells (such as immune and stromal cells). Furthermore, like hormones, miRNAs can be secreted and regulate gene expression in recipient cells. Altered expression levels of miRNAs in cancer cells determine the acquisition of fundamental biological capabilities (hallmarks of cancer) responsible for the development and progression of the disease.

miR-532-3p promotes hepatocellular carcinoma progression by targeting PTPRT

BACKGROUND

Aberrant expression of miR-532-3p was involved in progression and development of multiple cancers, whereas miR-532-3p has not been reported in hepatocellular carcinoma (HCC). The aim of this study was to elucidate the functions of miR-532-3p in progression of HCC.

METHODS

Real-time PCR in HCC tissues and cell lines and database analysis were conducted for detection of the expression of miR-532-3p in HCC. Then, the association of miR-532-3p with clinicopathological features and prognosis of HCC patients were statistically measured. Subsequently, we attempted to observe the effects of miR-532-3p on migration, invasion and proliferation of HCC cells by Wound healing assay, Transwell assays, MTT assay and EdU assay. Furthermore, bioinformatics tools, database analysis, luciferase reporter gene assay and rescue experiments were conducted to explore the target of miR-532-3p in HCC, and to explore whether the target mediated the effects of miR-532-3p on HCC cells.

RESULTS

Our findings and data from databases consistently indicated that the miR-532-3p expression level was higher in HCC. In addition, high miR-532-3p expression was found to be closely related to larger tumor size (P =  0.0027), presence of vascular invasion (P =  0.015), and advanced TNM stage (P =  0.015). In addition, experiments in vitro revealed that miR-532-3p promotes migration, invasion and proliferation of HCC cells. Furthermore, receptor protein tyrosine phosphatase T (PTPRT) was identified as the target and mediator of miR-532-3p in HCC cells.

CONCLUSION

Our results demonstrate that miR-532-3p, which is frequently up-regulated in HCC, contributes to HCC cells mobility and proliferation through targeting PTPRT.

Free Circulating miRNAs Measurement in Clinical Settings: The Still Unsolved Issue of the Normalization

Circulating molecules that are released into the circulation in response to specific stimuli are considered potential biomarkers for physiological or pathological processes. Their effective usefulness as biomarkers resides in their stability and high availability in all the biological fluids, combined with the limited invasiveness of intervention. Among the circulating molecules, miRNAs represent a novel class of biomarkers as they possess all the required characteristics such as sensitivity, predictivity, specificity, robustness, translatability, and noninvasiveness.

miRNAs are small non-coding RNAs, that act as inhibitors of protein translation, and intervene in the complex network of the post-transcriptional mechanisms finely regulating gene expression.

The emerging role of miRNAs as potential biomarkers for clinical applications (e.g., cancer and cardiovascular diseases diagnosis and prediction, musculoskeletal disease diagnosis and bone fracture risk prediction), however, requires the standardization of miRNA processing, from sample collection and sample storage, to RNA isolation, RNA reverse-transcription, and data analyses. Normalization is one of the most controversial issues related to quantitative Real-Time PCR data analysis since no universally accepted normalization strategies and reference genes exist, even more importantly, for circulating miRNA quantification. As it is widely demonstrated that the choice of different normalization strategies influences the results of gene expression analysis, it is important to select the most appropriate normalizers for each experimental set. This review discloses on the different strategies adopted in RT-qPCR miRNA normalization and the concerning issues to highlight on the need of a universally accepted methodology to make comparable the results produced by different studies.

Non-Coding RNAs and Resistance to Anticancer Drugs in Gastrointestinal Tumors

Non-coding RNAs are important regulators of gene expression and transcription. It is well established that impaired non-coding RNA expression especially the one of long non-coding RNAs and microRNAs is involved in a number of pathological conditions including cancer. Non-coding RNAs are responsible for the development of resistance to anticancer treatments as they regulate drug resistance-related genes, affect intracellular drug concentrations, induce alternative signaling pathways, alter drug efficiency via blocking cell cycle regulation, and DNA damage response. Furthermore, they can prevent therapeutic-induced cell death and promote epithelial-mesenchymal transition (EMT) and elicit non-cell autonomous mechanisms of resistance. In this review, we summarize the role of non-coding RNAs for different mechanisms resulting in drug resistance (e.g., drug transport, drug metabolism, cell cycle regulation, regulation of apoptotic pathways, cancer stem cells, and EMT) in the context of gastrointestinal cancers.

miRNAs: Important Targets for Oral Cancer Pain Research

Pain is a symptom shared by an incredible number of diseases. It is also one of the primary conditions that prompt individuals to seek medical treatment. Head and neck squamous cell carcinoma (HNSCC) corresponds to a heterogeneous disease that may arise from many distinct structures of a large, highly complex, and intricate region. HNSCC affects a great number of patients worldwide and is directly associated with chronic pain, which is especially prominent during the advanced stages of oral squamous cell carcinoma (OSCC), an anatomical and clinical subtype that corresponds to the great majority oral cancers. Although the cellular and molecular bases of oral cancer pain have not been fully established yet, the results of recent studies suggest that different epigenetic mechanisms may contribute to this process. For instance, there is strong scientific evidence that microRNAs (miRNAs), small RNA molecules that do not encode proteins, might act by regulating the mechanisms underlying cancer-related pain. Among the miRNAs that could possibly interfere in pain-signaling pathways, miR-125b, miR-181, and miR-339 emerge as some of the most promising candidates. In fact, such molecules apparently contribute to inflammatory pain. Moreover, these molecules possibly influence the activity of endogenous pain control systems (e.g., opioidergic and serotonergic systems), which could ultimately result in peripheral and central sensitization, central nervous system (CNS) phenomena innately associated with chronic pain. This review paper focuses on the current scientific knowledge regarding the involvement of miRNAs in cancer pain, with special attention dedicated to OSCC-related pain.