Specific alterations of microRNA transcriptome and global network structure in colorectal carcinoma after cetuximab treatment

miRNAs as cornerstones in colorectal cancer pathogenesis and resistance to therapy: A spotlight on signaling pathways interplay - A review

Colorectal cancer (CRC) is the world's third most prevalent cancer and the main cause of cancer-related mortality. A lot of work has been put into improving CRC patients' clinical care, including the development of more effective methods and wide biomarkers variety for prognostic, and diagnostic purposes. MicroRNAs (miRNAs) regulate a variety of cellular processes and play a significant role in the CRC progression and spread via controlling their target gene expression by translation inhibition or mRNA degradation. Consequently, dysregulation and disruption in their function, miRNAs are linked to CRC malignant pathogenesis by controlling several cellular processes involved in the CRC. These cellular processes include increased proliferative and invasive capacity, cell cycle aberration, evasion of apoptosis, enhanced EMT, promotion of angiogenesis and metastasis, and decreased sensitivity to major treatments. The miRNAs control cellular processes in CRC via regulation of pathways such as Wnt/β-catenin signaling, PTEN/AKT/mTOR axis, KRAS, TGFb signaling, VEGFR, EGFR, and P53. Hence, the goal of this review was to review miRNA biogenesis and present an updated summary of oncogenic and tumor suppressor (TS) miRNAs and their potential implication in CRC pathogenesis and responses to chemotherapy and radiotherapy. We also summarise the biological importance and clinical applications of miRNAs in the CRC.

Panitumumab and cetuximab affect differently miRNA expression in colorectal cancer cells

Background & aim: Resistance to anti-EGFR monoclonal antibodies in metastatic colorectal cancer (CRC) is frequent and prognostic biomarkers are lacking. MicroRNAs (miR) are good candidates in this context. We aimed to characterize cetuximab and panitumumab exposure influence on miR expression in colorectal cancer cells to identify those regulating the EGFR pathway and implicated in resistance to treatment. Finally, we aimed to identify miR expression in serum of patients with advanced CRC treated with cetuximab or panitumumab. Results: Cetuximab and panitumumab exposure induced significant expression variations of 17 miR out of a miRnome panel of 752. Six of those miR interacted with at least one downstream element of the EGFR pathway. Conclusion: After the bioinformatics two-phase process, five miR rarely described before could be potential actors of anti-EGFR monoclonal antibody resistance: miR-95-3p, miR-139-5p, miR-145-5p, miR-429 and miR-1247-5p. In vivo, we detected the expression of miR-139-5p and miR-145-5p in serum of patients with metastatic CRC.

The Mechanistic Roles of ncRNAs in Promoting and Supporting Chemoresistance of Colorectal Cancer

Colorectal Cancer (CRC) is one of the most common gastrointestinal malignancies which has quite a high mortality rate. Despite the advances made in CRC treatment, effective therapy is still quite challenging, particularly due to resistance arising throughout the treatment regimen. Several studies have been carried out to identify CRC chemoresistance mechanisms, with research showing different signalling pathways, certain ATP binding cassette (ABC) transporters and epithelial mesenchymal transition (EMT), among others to be responsible for the failure of CRC chemotherapies. In the last decade, it has become increasingly evident that certain non-coding RNA (ncRNA) families are involved in chemoresistance. Research investigations have demonstrated that dysregulation of microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) contribute towards promoting resistance in CRC via different mechanisms. Considering the currently available data on this phenomenon, a better understanding of how these ncRNAs participate in chemoresistance can lead to suitable solutions to overcome this problem in CRC. This review will first focus on discussing the different mechanisms of CRC resistance identified so far. The focus will then shift onto the roles of miRNAs, lncRNAs and circRNAs in promoting 5-fluorouracil (5-FU), oxaliplatin (OXA), cisplatin and doxorubicin (DOX) resistance in CRC, specifically using ncRNAs which have been recently identified and validated under in vivo or in vitro conditions.

MicroRNAs Involved in Inflammatory Breast Cancer: Oncogene and Tumor Suppressors with Possible Targets

Inflammatory breast cancer (IBC) as a rare and highly aggressive type of breast cancer displays phenotypic characteristics. To date, the IBC-associated molecular mechanisms are entirely unknown. In addition, there is an urgent need to identify the new biomarkers involved in the diagnosis and therapeutic purposes of IBC. MicroRNAs, a category of short noncoding RNAs, are capable of controlling the post-transcriptional expression of genes and thus can act as diagnostic predictive tools. In this review, we addressed the status of oncogenic and tumor suppressor miRNA-mediated IBC in current studies. Furthermore, based on their targets, their involvement in cancer progression, angiogenesis, metastasis, and apoptosis were determined.

Molecular mechanisms and clinical implications of miRNAs in drug resistance of colorectal cancer

Systemic chemotherapy is identified as a curative approach to prolong the survival time of patients with colorectal cancer (CRC). Although great progress in therapeutic approaches has been achieved during the last decades, drug resistance still extensively persists and serves as a major hurdle to effective anticancer therapy for CRC. The mechanism of multidrug resistance remains unclear. Recently, mounting evidence suggests that a great number of microRNAs (miRNAs) may contribute to drug resistance in CRC. Certain of these miRNAs may thus be used as promising biomarkers for predicting drug response to chemotherapy or serve as potential targets to develop personalized therapy for patients with CRC. This review mainly summarizes recent advances in miRNAs and the molecular mechanisms underlying miRNA-mediated chemoresistance in CRC. We also discuss the potential role of drug resistance-related miRNAs as potential biomarkers (diagnostic and prognostic value) and envisage the future orientation and challenges in translating the findings on miRNA-mediated chemoresistance of CRC into clinical applications.

The Liquid Biopsy in the Management of Colorectal Cancer: An Overview

Currently, there is a crucial need for novel diagnostic and prognostic biomarkers with high specificity and sensitivity in patients with colorectal cancer. A "liquid biopsy" is characterized by the isolation of cancer-derived components, such as circulating tumor cells, circulating tumor DNA, microRNAs, long non-coding RNAs, and proteins, from peripheral blood or other body fluids and their genomic or proteomic assessment. The liquid biopsy is a minimally invasive and repeatable technique that could play a significant role in screening and diagnosis, and predict relapse and metastasis, as well as monitoring minimal residual disease and chemotherapy resistance in colorectal cancer patients. However, there are still some practical issues that need to be addressed before liquid biopsy can be widely used in clinical practice. Potential challenges may include low amounts of circulating tumor cells and circulating tumor DNA in samples, lack of pre-analytical and analytical consensus, clinical validation, and regulatory endorsement. The aim of this review was to summarize the current knowledge of the role of liquid biopsy in the management of colorectal cancer.

Genetic and Epigenetic Modulation of Drug Resistance in Cancer: Challenges and Opportunities

Cancer is a complex disease that has the ability to develop resistance to traditional therapies. The current chemotherapeutic treatment has become increasingly sophisticated, yet it is not 100% effective against disseminated tumours. Anticancer drugs resistance is an intricate process that ascends from modifications in the drug targets suggesting the need for better targeted therapies in the therapeutic arsenal. Advances in the modern techniques such as DNA microarray, proteomics along with the development of newer targeted drug therapies might provide better strategies to overcome drug resistance. This drug resistance in tumours can be attributed to an individual's genetic differences, especially in tumoral somatic cells but acquired drug resistance is due to different mechanisms, such as cell death inhibition (apoptosis suppression) altered expression of drug transporters, alteration in drug metabolism epigenetic and drug targets, enhancing DNA repair and gene amplification. This review also focusses on the epigenetic modifications and microRNAs, which induce drug resistance and contributes to the formation of tumour progenitor cells that are not destroyed by conventional cancer therapies. Lastly, this review highlights different means to prevent the formation of drug resistant tumours and provides future directions for better treatment of these resistant tumours.

Expression signatures and roles of microRNAs in inflammatory breast cancer

Inflammatory breast cancer (IBC) is an infrequent but aggressive manifestation of breast cancer, which accounts for 2–4% of all breast cancer cases but responsible for 7–10% of breast cancer-related deaths, and with a 20–30% 10-year overall survival compared with 80% for patients with non-IBC with an unordinary phenotype, whose molecular mechanisms are still largely unknown to date. Discovering and identifying novel bio-markers responsible for diagnosis and therapeutic targets is a pressing need. MicroRNAs are a class of small non-coding RNAs that are capable to post-transcriptionally regulate gene expression of genes by targeting mRNAs, exerting vital and tremendous affects in numerous malignancy-related biological processes, including cell apoptosis, metabolism, proliferation and differentiation. In this study, we review present and high-quality evidences regarding the potential applications of inflammatory breast cancer associated microRNAs for diagnosis and prognosis of this lethal disease.

MiR-486-5p Downregulation Marks an Early Event in Colorectal Carcinogenesis

BACKGROUND

MicroRNAs are dysregulated in colorectal cancer and subsets correlated with advanced tumor stage and metastasis. Data are lacking on microRNA dysregulation from early to late-stage disease.

OBJECTIVE

The purpose of this study was to identify a microRNA signature associated with the primary tumor and metastatic site in stage IV disease and to examine whether the signature is evident in earlier stages.

DESIGN

A microRNA profile was generated and then explored in normal colon tissue (n = 5), early stage (stage I and II; n = 10), and late-stage (stage III and IV; n = 14) colorectal primary tumors via polymerase chain reaction to delineate molecular events that may promote colorectal carcinogenesis.

SETTING

Genome-wide microRNA expression profiling was performed.

PATIENTS

A total of 14 patient-matched stage IV primary colorectal cancer tumors and corresponding liver metastases were included.

MAIN OUTCOME MEASURES

MicroRNA array technology was used to identify microRNA expression-predictive metastatic potential in the primary tumor.

RESULTS

A distinct 9-member signature group of microRNAs was concurrent in stage IV primary colorectal cancer and their corresponding liver metastases, when compared with surrounding unaffected colon and liver tissue (microRNA-18b, microRNA-93, microRNA-182, microRNA-183, microRNA21, microRNA-486-5p, microRNA-500a, microRNA-552, and microRNA-941). Of the microRNA panel, only microRNA486-5p was differentially expressed in early stage colorectal cancer samples compared with normal tissue (p = 0.001) and additionally differentially expressed between late-stage colorectal cancer samples and normal tissue (p < 0.01).

LIMITATIONS

Our microRNA profile was generated in a small subset of patients and will require validation in more samples.

CONCLUSIONS

We identified a distinct microRNA signature in primary colon and matched metastatic disease. On additional investigation, 1 microRNA was differentially expressed in both early and late-stage cancer patient samples, and it may herald an early event in colorectal carcinogenesis. This study warrants additional investigation with a larger patient cohort to better understand the effect of microRNAs in carcinogenesis. See Video Abstract at http://links.lww.com/DCR/A723.

MicroRNAs in cancer drug resistance: Basic evidence and clinical applications

Development of drug resistance has considerably limited the efficacy of cancer treatments, including chemotherapy and targeted therapies. Hence, understanding the molecular mechanisms underpinning the innate or the acquired resistance to these therapies is critical to improve drug efficiency and clinical outcomes. Several studies have implicated microRNAs (miRNA) in this process. MiRNAs repress gene expression by specific binding to complementary sequences in the 3' region of target messenger RNAs (mRNAs), followed by target mRNA degradation or blocked translation. By targeting molecules specific to a particular pathway within tumor cells, the new generation of cancer treatment strategies has shown significant advantages over conventional chemotherapy. However, the long-term efficacy of targeted therapies often remains poor, because tumor cells develop resistance to such therapeutics. Targeted therapies often involve monoclonal antibodies (mAbs), such as those blocking the ErB/HER tyrosine kinases, epidermal growth factor receptor (cetuximab) and HER2 (trastuzumab), and those inhibiting vascular endothelial growth factor receptor signaling (e.g., bevacizumab). Even though these are among the most used agents in tumor medicine, clinical response to these drugs is reduced due to the emergence of drug resistance as a result of toxic effects in the tumor microenvironment. Research on different types of human cancers has revealed that aberrant expression of miRNAs promotes resistance to the aforementioned drugs. In this study, we review the mechanisms of tumor cell resistance to mAb therapies and the role of miRNAs therein. Emerging treatment strategies combine therapies using innovative miRNA mimics or antagonizers with conventional approaches to maximize outcomes of patients with cancer.

MicroRNAs in the prognosis and therapy of colorectal cancer: From bench to bedside

MicroRNAs (miRNAs) are small, single-stranded, noncoding RNAs that can post-transcriptionally regulate the expression of various oncogenes and tumor suppressor genes. Dysregulated expression of many miRNAs have been shown to mediate the signaling pathways critical in the multistep carcinogenesis of colorectal cancer (CRC). MiRNAs are stable and protected from RNase-mediated degradation, thereby enabling its detection in biological fluids and archival tissues for biomarker studies. This review focuses on the role and application of miRNAs in the prognosis and therapy of CRC. While stage II CRC is potentially curable by surgical resection, a significant percentage of stage II CRC patients do develop recurrence. MiRNA biomarkers may be used to stratify such high-risk population for adjuvant chemotherapy to provide better prognoses. Growing evidence also suggests that miRNAs are involved in the metastatic process of CRC. Certain of these miRNAs may thus be used as prognostic biomarkers to identify patients more likely to have micro-metastasis, who could be monitored more closely after surgery and/or given more aggressive adjuvant chemotherapy. Intrinsic and acquired resistance to chemotherapy severely hinders successful chemotherapy in CRC treatment. Predictive miRNA biomarkers for response to chemotherapy may identify patients who will benefit the most from a particular regimen and also spare the patients from unnecessary side effects. Selection of patients to receive the new targeted therapy is becoming possible with the use of predictive miRNA biomarkers. Lastly, forced expression of tumor suppressor miRNA or silencing of oncogenic miRNA in tumors by gene therapy can also be adopted to treat CRC alone or in combination with other chemotherapeutic drugs.

Discriminatory miRNAs for the Management of Papillary Thyroid Carcinoma and Noninvasive Follicular Thyroid Neoplasms with Papillary-Like Nuclear Features

BACKGROUND

Papillary thyroid carcinoma (PTC) variants have several overlapping clinical and pathological features. The World Health Organization recently published a new classification of thyroid tumors containing significant revisions. Encapsulated papillary thyroid carcinoma (EPTC) has been recognized as a distinctive variant of PTC. The noninvasive encapsulated follicular variant of PTC has been reclassified as noninvasive follicular thyroid neoplasms with papillary-like nuclear features (NIFTP). Different neoplasms are associated with different outcomes and require different clinical management. The objective of this study was to explore the miRNA expression patterns specific for classic PTC (cPTC), EPTC, follicular variant of PTC, and NIFTP in order to identify biomarkers of diagnostic and prognostic utility aiming for better clinical decisions.

METHODS

The expression of 84 miRNAs was determined by quantitative real-time polymerase chain reaction in 113 thyroid tissues of PTC (classic, encapsulated, and follicular), NIFTP, and hyperplasia lesions. Expression of the same miRNAs was tested in pre- and postoperative whole-blood samples.

RESULTS

Several miRNAs were differentially expressed in the different groups. Expression profile of miRNAs in the tissue was similarly reflected in the circulation. Receiver operating characteristic curve analysis showed that miR-7-5p, miR-222-3p, and miR-146b-5p can discriminate between the different groups with high sensitivity and specificity. Downregulation of miR-144-3p, miR-15a-5p, miR-20a-5p, miR-32-5p miR-142-5p, miR-143-3p, and miR-20b-5p is associated with aggressive behavior in cPTC. Circulating miR-146b-5p, miR-222-3p, miR-155-5p, and miR-378a-3p are potential diagnostic and follow up biomarkers for PTC.

CONCLUSION

Downregulation of miR-7-5p discriminates NIFTP from hyperplasia. Upregulation of miR-222-3p discriminates follicular variant of PTC from NIFTP. High levels of miR-146b-5p distinctively characterize cPTC. These miRNAs are useful biomarkers in the diagnosis of PTC and NIFTP, and help to avoid unnecessary thyroidectomy and improve clinical management.

The correlation analysis of miRNAs and target genes in metastasis of cervical squamous cell carcinoma

Aim: This study was intended to identify the metastasis-related miRNAs and target genes in cervical squamous cell carcinoma. Materials & methods: The mRNA and miRNA next-generation sequencing data were downloaded. Differential expression analysis was carried out, followed by target gene prediction of differentially expressed miRNAs. The biological function of differentially expressed genes was performed. Validation was carried out by survival analysis and qRT-PCR. Results: N4BP3 were associated with the survival time of patients. Hsa-mir-451 and hsa-mir-486 were related to tumor differentiation stage. Validated expression of hsa-mir-24–2, hsa-mir-582, NOTCH1, PIP4K2B, DIP2B and IGFBP5 was consistent with the bioinformatics analysis. Conclusion: Alterations of miRNAs and target genes may be useful in understanding the metastasis mechanisms of cervical squamous cell carcinoma.

MicroRNA expression profiles and clinicopathological implications in lung adenocarcinoma according to EGFR, KRAS, and ALK status

Lung adenocarcinoma has distinctive clinicopathological features that are related to specific genetic alterations, including EGFR and KRAS mutations and ALK rearrangement. MicroRNAs are small non-coding RNAs that post-transcriptionally regulate many important biological processes and influence cancer phenotypes. This study retrospectively investigated microRNA expression profiles, and their clinicopathological implications, in lung adenocarcinoma according to genetic status (EGFR, KRAS, ALK, and triple negative). A total of 72 surgically resected lung adenocarcinoma specimens (19 EGFR-mutated, 17 KRAS-mutated, 16 ALK-rearranged, and 20 triple negative cancers) were screened for 23 microRNAs using quantitative real-time reverse transcriptase polymerase chain reaction. We then evaluated the associations between the microRNA expressions and the cancers’ genetic and clinicopathological features. Eight microRNAs were associated with clinicopathological features, such as male sex and ever-smoker status (high miR-373-3p, miR-1343-3p, miR-138-1-3p, and miR-764; low miR-27b-3p) and vascular invasion (high miR-27b-3p; low miR-1343-3p and miR-764). Clustering and discriminant analyses revealed that the microRNA expression patterns in the ALK group were different from those in the EGFR and KRAS groups. Five microRNAs (high miR-1343-3p; low miR-671-3p, miR-103a-3p, let-7e, and miR-342-3p) were especially distinctive in the ALK group, compared to the EGFR and KRAS groups. Moreover, a significant association was observed between ALK-rearrangement, decreased miR-342-3p expression, and immunohistochemical loss of E-cadherin. Therefore, microRNA expression profiles appear to have distinctive clinicopathological implications in ALK-rearranged lung adenocarcinoma. Furthermore, the association of ALK rearrangement, decreased miR-342-3p expression, and E-cadherin loss might indicate that miR-342-3p is involved in the ALK-associated phenotypes and epithelial-mesenchymal transition.

Concentration of circulating miRNA-containing particles in serum enhances miRNA detection and reflects CRC tissue-related deregulations

The emerging potential of miRNAs as biomarkers for cancer detection demands parallel evaluation of strategies for reliable identification of disease-related signatures from easily accessible and pertinent body compartments. Here, we addressed whether efficient concentration of circulating miRNA-carrying particles is a rationale for miRNA biomarker discovery. We systematically compared miRNA signatures in 93 RNA preparations from three serum entities (whole serum, particle-concentrated, and particle-depleted fractions) and corresponding tissue samples from patients with colorectal cancer (CRC) as a model disease. Significant differences between whole sera and particle-concentrated serum fractions of CRC patients emerged for 45 of 742 tested miRNAs. Twenty-eight of these 45 miRNAs were differentially expressed between particle-concentrated serum fractions of metastatic CRC- and healthy individuals. Over half of these candidates (15 of 28) showed deregulations only in concentrated serum fractions, but not in whole sera, compared to the respective controls.Our results also provided evidence of a consistent downregulation of miR-486 and miR-92a, and further showed a possible "strand-specific" deregulation of extracellular miRNAs in CRC. More importantly, most of the identified miRNAs in the enriched sera reflected the patterns of the corresponding tumor tissues and showed links to cancer-related inflammation. Further investigation of seven serum pools revealed a subset of potential extracellular miRNA candidates to be implicated in both neoplastic and inflammatory bowel disease.Our findings demonstrate that enrichment and sensitive detection of miRNA carriers is a promising approach to detect CRC-related pathological changes in liquid biopsies, and has potential for clinical diagnostics.

miR-486-5p expression pattern in esophageal squamous cell carcinoma, gastric cancer and its prognostic value

Micro RNA (miR)-486-5p is often aberrantly expressed in human cancers. The aim of this study was to identify the prognostic value of miR-486-5p expression in digestive system cancers. Tissue microarrays were constructed with 680 samples including 185 esophageal squamous cell carcinomas (ESCCs), 90 gastric adenocarcinomas (GCs), and 60 digestive system cancer tissues from 10 ESCC, 10 GC, 10 colon, 10 rectum, 10 liver, 10 pancreatic cancer, and corresponding normal tissues. Twenty normal digestive system mucosa tissues from healthy volunteers were included as normal controls. In GC, miR-486-5p expression was decreased in 62.8% of cases (59/94), increased in 33.0% (31/94), and unchanged in 4.2% (4/94); in ESCC its expression was decreased in 66.2% (129/195), increased in 32.3% (63/195), and unchanged in 1.5% (3/195). Expression of miR-486-5p was decreased in 12, and increased in 8, of 20 cases of colon or rectum cancer; decreased in 6, and increased in 4, of 10 cases of liver cancer; and decreased in 8, and increased in 2, of 10 cases of pancreatic cancer. Multivariate and univariate regression analysis demonstrated that low/unchanged miR-486-5p predicted poor prognosis in ESCC (hazard ratio [HR], 4.32; 95% confidence interval [CI], 2.62–7.14; P < 0.001; HR, 3.88; 95% CI, 2.43–6.22; P < 0.001, respectively) and GC (HR, 2.46; 95% CI, 1.35–4.50; P = 0.003; HR, 2.55; 95% CI, 1.39–4.69; P = 0.002, respectively). MiR-486-5p might therefore be an independent tumor marker for evaluating prognosis in patients with ESCC or GC.

miR-486-3p, miR-139-5p, and miR-21 as Biomarkers for the Detection of Oral Tongue Squamous Cell Carcinoma

Oral tongue squamous cell carcinoma (TSCC) is a complex disease with extensive genetic and epigenetic defects, including microRNA deregulation. The aims of the present study were to test the feasibility of performing the microRNA profiling analysis on archived TSCC specimens and to assess the potential diagnostic utility of the identified microRNA biomarkers for the detection of TSCC. TaqMan array-based microRNA profiling analysis was performed on 10 archived TSCC samples and their matching normal tissues. A panel of 12 differentially expressed microRNAs was identified. Eight of these differentially expressed microRNAs were validated in an independent sample set. A random forest (RF) classification model was built with miR-486-3p, miR-139-5p, and miR-21, and it was able to detect TSCC with a sensitivity of 100% and a specificity of 86.7% (overall error rate = 6.7%). As such, this study demonstrated the utility of the archived clinical specimens for microRNA biomarker discovery. The feasibility of using microRNA biomarkers (miR-486-3p, miR-139-5p, and miR-21) for the detection of TSCC was confirmed.

Non-coding RNAs Enabling Prognostic Stratification and Prediction of Therapeutic Response in Colorectal Cancer Patients

Colorectal cancer (CRC) is a heterogeneous disease and current treatment options for patients are associated with a wide range of outcomes and tumor responses. Although the traditional TNM staging system continues to serve as a crucial tool for estimating CRC prognosis and for stratification of treatment choices and long-term survival, it remains limited as it relies on macroscopic features and cases of surgical resection, fails to incorporate new molecular data and information, and cannot perfectly predict the variety of outcomes and responses to treatment associated with tumors of the same stage. Although additional histopathologic features have recently been applied in order to better classify individual tumors, the future might incorporate the use of novel molecular and genetic markers in order to maximize therapeutic outcome and to provide accurate prognosis. Such novel biomarkers, in addition to individual patient tumor phenotyping and other validated genetic markers, could facilitate the prediction of risk of progression in CRC patients and help assess overall survival. Recent findings point to the emerging role of non-protein-coding regions of the genome in their contribution to the progression of cancer and tumor formation. Two major subclasses of non-coding RNAs (ncRNAs), microRNAs and long non-coding RNAs, are often dysregulated in CRC and have demonstrated their diagnostic and prognostic potential as biomarkers. These ncRNAs are promising molecular classifiers and could assist in the stratification of patients into appropriate risk groups to guide therapeutic decisions and their expression patterns could help determine prognosis and predict therapeutic options in CRC.

MicroRNAs as a tool to aid stratification of colorectal cancer patients and to guide therapy

Colorectal cancer is a common type of malignant disease with high rates of morbidity and mortality. Although treatment options have been expanded over the last years, the mainstay of curative treatment remains surgical removal of the tumor-bearing organ. Systemic treatment options include classic cytotoxic drugs as well as some biological agents. Noncoding RNAs are an evolving field in cancer diagnosis, prognosis and possible treatment. Noncoding miRNAs are small molecules with huge impact on gene expression. They have been a substantial part of cancer research for more than a decade. In this review article, the current knowledge of miRNAs and colorectal cancer diagnosis, prognosis and novel or evolving therapeutic concepts are discussed. Examples of how miRNAs might change the management of the disease will be described.

Microarray Analysis of Circular RNA Expression Profile Associated with 5-Fluorouracil-Based Chemoradiation Resistance in Colorectal Cancer Cells

Preoperative 5-fluorouracil- (5-FU-) based chemoradiotherapy is a standard treatment for locally advanced colorectal cancer (CRC). However, the effect of 5-FU-based chemoradiotherapy on CRC is limited due to the development of chemoradiation resistance (CRR), and the molecular mechanisms underlying this resistance are yet to be investigated. Recently, circular RNAs (circRNAs), which can function as microRNA sponges, were found to be involved in the development of several cancers. In this study, we focused on clarifying the modulation of the expression profiles of circRNAs in CRR. Microarray analysis identified 71 circRNAs differentially expressed in chemoradiation-resistant CRC cells. Among them, 47 were upregulated and 24 were downregulated by more than twofold. Furthermore, expression modulation of five representative circRNAs was validated by quantitative reverse transcription PCR (qRT-PCR). Moreover, these modulated circRNAs were predicted to interact with 355 miRNAs. Furthermore, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that the most modulated circRNAs regulate several cancers and cancer-related pathways, and the possible mechanism underlying CRR was discussed. This is the first report revealing the circRNA modulations in 5-FU chemoradiation-resistant CRC cells by microarray. The study provided a useful database for further understanding CRR and presents potential targets to overcome CRR in CRC.

Colorectal Cancer: From the Genetic Model to Posttranscriptional Regulation by Noncoding RNAs

Colorectal cancer is the third most common form of cancer in developed countries and, despite the improvements achieved in its treatment options, remains as one of the main causes of cancer-related death. In this review, we first focus on colorectal carcinogenesis and on the genetic and epigenetic alterations involved. In addition, noncoding RNAs have been shown to be important regulators of gene expression. We present a general overview of what is known about these molecules and their role and dysregulation in cancer, with a special focus on the biogenesis, characteristics, and function of microRNAs. These molecules are important regulators of carcinogenesis, progression, invasion, angiogenesis, and metastases in cancer, including colorectal cancer. For this reason, miRNAs can be used as potential biomarkers for diagnosis, prognosis, and efficacy of chemotherapeutic treatments, or even as therapeutic agents, or as targets by themselves. Thus, this review highlights the importance of miRNAs in the development, progression, diagnosis, and therapy of colorectal cancer and summarizes current therapeutic approaches for the treatment of colorectal cancer.

miR-486-3p, miR-139-5p, and miR-21 as Biomarkers for the Detection of Oral Tongue Squamous Cell Carcinoma

Oral tongue squamous cell carcinoma (TSCC) is a complex disease with extensive genetic and epigenetic defects, including microRNA deregulation. The aims of the present study were to test the feasibility of performing the microRNA profiling analysis on archived TSCC specimens and to assess the potential diagnostic utility of the identified microRNA biomarkers for the detection of TSCC. TaqMan array-based microRNA profiling analysis was performed on 10 archived TSCC samples and their matching normal tissues. A panel of 12 differentially expressed microRNAs was identified. Eight of these differentially expressed microRNAs were validated in an independent sample set. A random forest (RF) classification model was built with miR-486-3p, miR-139-5p, and miR-21, and it was able to detect TSCC with a sensitivity of 100% and a specificity of 86.7% (overall error rate = 6.7%). As such, this study demonstrated the utility of the archived clinical specimens for microRNA biomarker discovery. The feasibility of using microRNA biomarkers (miR-486-3p, miR-139-5p, and miR-21) for the detection of TSCC was confirmed.

Dysregulated miR-671-5p / CDR1-AS / CDR1 / VSNL1 axis is involved in glioblastoma multiforme

MiR-671-5p is encoded by a gene localized at 7q36.1, a region amplified in human glioblastoma multiforme (GBM), the most malignant brain cancer. To investigate whether expression of miR-671-5p were altered in GBM, we analyzed biopsies from a cohort of forty-five GBM patients and from five GBM cell lines. Our data show significant overexpression of miR-671-5p in both biopsies and cell lines. By exploiting specific miRNA mimics and inhibitors, we demonstrated that miR-671-5p overexpression significantly increases migration and to a less extent proliferation rates of GBM cells. Through a combined in silico and in vitro approach, we identified CDR1-AS, CDR1, VSNL1 as downstream miR-671-5p targets in GBM. Expression of these genes significantly decreased both in GBM biopsies and cell lines and negatively correlated with that of miR-671-5p. Based on our data, we propose that the axis miR-671-5p / CDR1-AS / CDR1 / VSNL1 is functionally altered in GBM cells and is involved in the modification of their biopathological profile.

Downregulated miR-486-5p acts as a tumor suppressor in esophageal squamous cell carcinoma

microRNAs (miRNAs/miRs) are crucial regulators of gene expression at the post-translational level through promoting mRNA degradation or the repression of translation of target genes. miRs have been confirmed to serve a dominant role in tumor biology. miR-486-5p has been ascertained to be involved in non-small-cell lung cancer, breast cancer and hepatocellular carcinoma; however, the expression and function of miR-486-5p in esophageal squamous cell carcinoma (ESCC) has yet to be elucidated. The present study aimed to analyze the expression levels of miR-486-5p in ESCC tissues and paired normal adjacent tissues, and determine the effects of miR-486-5p on esophageal cancer cells using MTT, wound scratch and apoptosis assays. The current results showed that miR-486-5p was significantly downregulated in ESCC specimens. Ectopic expression of miR-486-5p by synthetic mimics reduced cell proliferation and migration and induced increased cell apoptosis. The results indicated miR-486-5p may function as a tumor suppressor in ESCC. The present study demonstrated that miR-486-5p was downregulated in ESCC and served a anti-oncogene role in ESCC via affecting cellular migration.

MicroRNA-486-5p enhances hepatocellular carcinoma tumor suppression through repression of IGF-1R and its downstream mTOR, STAT3 and c-Myc

The insulin-like growth factor (IGF)-axis has been paradigmatically involved in hepatocellular carcinoma (HCC) tumor initiation, progression and drug resistance. Consequently, members of the IGF-axis and most importantly, IGF-1 receptor (IGF-1R) have been considered as intriguing targets for HCC therapy. Few miRNAs have been recently reported to be associated with IGF-1R regulation. The present study aimed to investigate the role of microRNA (miRNA/miR)-486-5p in the regulation of IGF-1R and its downstream signaling cascades. miR-486-5p was markedly downregulated in hepatitis C virus-induced HCC tissues and Huh-7 cells. Forcing the expression of miR-486-5p in Huh-7 cells resulted in the repression of IGF-1R, mammalian target of rapamycin (mTOR), signal transducer and activator of transcription 3 (STAT3) and c-Myc mRNA levels. Ectopic expression of miR-486-5p in Huh-7 cells markedly repressed cellular viability, proliferation, migration and clonogenicity in a similar pattern to IGF-1R small interfering RNAs, and were evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, BrdU incorporation, wound healing and colony forming assays, respectively. Overall, the study findings demonstrated that miR-486-5p acts as a tumor suppressor in HCC through the repression of essential members of the IGF-axis, including IGF-1R and its downstream mediators mTOR, STAT3 and c-Myc.

miRNAs: mediators of ErbB family targeted therapy resistance

The ErbB/HER tyrosine kinase receptors family plays a key regulatory role in different cellular processes by activating several signaling pathways. In different tumor types, mutations or overexpression of the ErbB family members are a common feature, which led to the development of targeted therapies against this receptors. Although with this kind of treatment we are heading to a more personalized medicine, the development of acquired resistance is still an issue, therefore, several studies focused on discovering the mechanisms behind it. More recently, miRNAs have been described as important mediators of acquired resistance, specifically, acquired resistance to ErbB family targeted therapies. Ultimately, miRNA-based therapeutics using exosomes as a drug delivery model can revolutionize today's approach of cancer treatment.

Noncoding RNA and colorectal cancer: its epigenetic role

The use of novel sequencing and high-throughput techniques has become widespread, and are now readily available to obtain the comprehensive transcription profile of the human genome. Noncoding RNAs (ncRNAs) are transcripts that have no apparent protein-coding capacity, but they have important roles in human physiology. Most research in this area has focused on micro-RNAs. However, the role of long ncRNAs (lncRNAs) as drivers of tumor suppression and oncogenic functions has recently been examined in numerous cancer types. Epigenetic alterations can reportedly deregulate the expression of any type of transcript. However, the exact mechanisms of epigenetic regulation of lncRNA are still unknown. In this review, the authors primarily focus on the epigenetic effects modulating ncRNA in colorectal cancer (CRC). The authors specifically discuss examples of oncogenic ncRNA in CRC pathobiology, as well as its extended diagnosis, prognosis and therapy.

Colorectal cancer carcinogenesis: a review of mechanisms

Colorectal cancer (CRC) is the second most common cancer in women and the third most common in men globally. CRC arises from one or a combination of chromosomal instability, CpG island methylator phenotype, and microsatellite instability. Genetic instability is usually caused by aneuploidy and loss of heterozygosity. Mutations in the tumor suppressor or cell cycle genes may also lead to cellular transformation. Similarly, epigenetic and/or genetic alterations resulting in impaired cellular pathways, such as DNA repair mechanism, may lead to microsatellite instability and mutator phenotype. Non-coding RNAs, more importantly microRNAs and long non-coding RNAs have also been implicated at various CRC stages. Understanding the specific mechanisms of tumorigenesis and the underlying genetic and epigenetic traits is critical in comprehending the disease phenotype. This paper reviews these mechanisms along with the roles of various non-coding RNAs in CRCs.

Colorectal cancer carcinogenesis: a review of mechanisms

Colorectal cancer (CRC) is the second most common cancer in women and the third most common in men globally. CRC arises from one or a combination of chromosomal instability, CpG island methylator phenotype, and microsatellite instability. Genetic instability is usually caused by aneuploidy and loss of heterozygosity. Mutations in the tumor suppressor or cell cycle genes may also lead to cellular transformation. Similarly, epigenetic and/or genetic alterations resulting in impaired cellular pathways, such as DNA repair mechanism, may lead to microsatellite instability and mutator phenotype. Non-coding RNAs, more importantly microRNAs and long non-coding RNAs have also been implicated at various CRC stages. Understanding the specific mechanisms of tumorigenesis and the underlying genetic and epigenetic traits is critical in comprehending the disease phenotype. This paper reviews these mechanisms along with the roles of various non-coding RNAs in CRCs.

MicroRNA Expression Profiles in Papillary Thyroid Carcinoma, Benign Thyroid Nodules and Healthy Controls

MicroRNAs (miRNAs) represent a class of short endogenous non-coding RNAs that negatively regulate gene expression at the post-transcriptional level in many biological processes, including proliferation, differentiation, stress response and apoptosis. In this study we analyzed a set of seven miRNA molecules in sera of patients with papillary thyroid cancer, multinodular goiter and healthy controls to identify miRNA molecules that may have utility as markers for PTC. MiR-21 serum levels in the preoperative PTC and MG groups were significantly higher than the control group. Likewise, postoperative levels of miR-151-5p, miR-221 and miR-222 were significantly lower in patients with PTC. When serum miRNA levels were evaluated according to stage, postoperative levels of miR-151-5p and miR-222 were significantly lower in patients with advanced stages of the disease. The miRNA levels were also found associated with the size of the primary tumor. Our data imply that specific miRNA molecules which are differentially expressed in thyroid tumors may play role in the development of papillary thyroid carcinoma.

miRNAs Plasma Profiles in Vascular Dementia: Biomolecular Data and Biomedical Implications

Vascular dementia (VaD) is a pathogenetically heterogeneous neuropsychiatric syndrome, mainly characterized by cognitive impairment. Among dementias, it is second by incidence after Alzheimer’s dementia (AD). VaD biomolecular bases have been poorly characterized, but vascular-linked factors affecting the CNS and its functions are generally hypothesized to perform a major role, together with cardiovascular and immunological factors. miRNAs, which perform critically important biomolecular roles within cell networks, are also found in biological fluids as circulating miRNAs (cmiRNAs). We hypothesized that differentially expressed (DE) cmiRNAs in plasma from VaD patients could be applied to diagnose VaD through liquid biopsies; these profiles also could allow to start investigating VaD molecular bases. By exploiting TaqMan Low-Density Arrays and single TaqMan assays, miR-10b*, miR29a-3p, and miR-130b-3p were discovered and validated as significantly downregulated DE cmiRNAs in VaD patients compared to unaffected controls (NCs). These miRNAs also were found to be significantly downregulated in a matched cohort of AD patients, but miR-130b-3p levels were lower in AD than in VaD. A negative correlation was detected between miR-29a and miR-130b expression and cognitive impairment in VaD and AD, respectively. Receiver operating characteristic curves demonstrated that decreased plasma levels of miR-10b*, miR29a-3p, and miR-130b-3p allow to discriminate VaD and AD patients from NCs. Furthermore, the concurrent downregulation of both miR-10b* and miR-130b-3p in VaD showed an area under the curve (AUC) of 0.789 (p < 0.0001) with 75% of sensitivity and 72% of specificity, whereas an AUC of 0.789 (p < 0.0001) with 92% of sensitivity and 81% of specificity was found for both in AD. The miRNAs profiles reported in this paper pave the way to translational applications to molecular VaD diagnosis, but they also should allow to further investigate on its molecular bases.

Non-coding landscapes of colorectal cancer

For two decades Vogelstein’s model has been the paradigm for describing the sequence of molecular changes within protein-coding genes that would lead to overt colorectal cancer (CRC). This model is now too simplistic in the light of recent studies, which have shown that our genome is pervasively transcribed in RNAs other than mRNAs, denominated non-coding RNAs (ncRNAs). The discovery that mutations in genes encoding these RNAs [i.e., microRNAs (miRNAs), long non-coding RNAs, and circular RNAs] are causally involved in cancer phenotypes has profoundly modified our vision of tumour molecular genetics and pathobiology. By exploiting a wide range of different mechanisms, ncRNAs control fundamental cellular processes, such as proliferation, differentiation, migration, angiogenesis and apoptosis: these data have also confirmed their role as oncogenes or tumor suppressors in cancer development and progression. The existence of a sophisticated RNA-based regulatory system, which dictates the correct functioning of protein-coding networks, has relevant biological and biomedical consequences. Different miRNAs involved in neoplastic and degenerative diseases exhibit potential predictive and prognostic properties. Furthermore, the key roles of ncRNAs make them very attractive targets for innovative therapeutic approaches. Several recent reports have shown that ncRNAs can be secreted by cells into the extracellular environment (i.e., blood and other body fluids): this suggests the existence of extracellular signalling mechanisms, which may be exploited by cells in physiology and pathology. In this review, we will summarize the most relevant issues on the involvement of cellular and extracellular ncRNAs in disease. We will then specifically describe their involvement in CRC pathobiology and their translational applications to CRC diagnosis, prognosis and therapy.

Expression profile analysis of microRNAs and downregulated miR-486-5p and miR-30a-5p in non-small cell lung cancer

Lung cancer is the leading cause of cancer-related mortality worldwide and although there have been improvements in treatment there is a low survival rate. The aim of the present study was to investigate the effect of microRNA (miRNA) on cell pathways. A miRNA microarray was used to profile miRNAs of lung cancer tissues. It was identified that 33 miRNAs with >2.0-fold change and FDR <0.05 were differentially expressed between the adjacent non-cancerous lung tissues and non-small cell lung cancers NSCLCs (P<0.005). The data were optimized in combination with physical interaction analysis to obtain crucial miRNAs. The results showed that differentially expressed miRNAs were associated with biological processes such as cell migration, protein phosphorylation and neuron differentiation, and signaling pathways such as MAPK, TGF-β and PI3K/Akt signaling pathways. Validation of significant miRNAs in independent 40 paired NSCLC tissues demonstrated that the expression level of miR-486-5p and miR-30a-5p was significantly downregulated in another 40 paired lung cancer tissues. Taken together, the results provided strong evidence of the possible involvement of miRNAs in the development and progression of NSCLC. Thus, the results are of importance for clinical investigators and for those who design miRNA‑based novel cancer therapeutics.

MicroRNA-224 is associated with colorectal cancer progression and response to 5-fluorouracil-based chemotherapy by KRAS-dependent and -independent mechanisms

Background:

Colorectal cancers arise from benign adenomas, although not all adenomas progress to cancer and there are marked interpatient differences in disease progression. We have previously associated KRAS mutations with disease progression and reduced survival in colorectal cancer patients.

Methods:

We used TaqMan low-density array (TLDA) qRT–PCR analysis to identify miRNAs differentially expressed in normal colorectal mucosa, adenomas and cancers and in isogeneic KRAS WT and mutant HCT116 cells, and used a variety of phenotypic assays to assess the influence of miRNA expression on KRAS activity, chemosensitivity, proliferation and invasion.

Results:

MicroRNA-224 was differentially expressed in dysplastic colorectal disease and in isogeneic KRAS WT and mutant HCT116 cells. Antagomir-mediated miR-224 silencing in HCT116 KRAS WT cells phenocopied KRAS mutation, increased KRAS activity and ERK and AKT phosphorylation. 5-FU chemosensitivity was significantly increased in miR-224 knockdown cells, and in NIH3T3 cells expressing KRAS and BRAF mutant proteins. Bioinformatics analysis of predicted miR-224 target genes predicted altered cell proliferation, invasion and epithelial–mesenchymal transition (EMT) phenotypes that were experimentally confirmed in miR-224 knockdown cells.

Conclusions:

We describe a novel mechanism of KRAS regulation, and highlight the clinical utility of colorectal cancer-specific miRNAs as disease progression or clinical response biomarkers.

Combinational treatment with microRNA‑133b and cetuximab has increased inhibitory effects on the growth and invasion of colorectal cancer cells by regulating EGFR

Colorectal cancer (CRC) is the third most common cancer with a very poor prognosis predominantly due to its high rate of tumor invasion and migration, and its resistance to anti‑epidermal growth factor receptor (EGFR) therapy. Although CRC has been widely studied, the underlying molecular mechanism remains to be elucidated. MicroRNA (miR)‑133b has been demonstrated to act as a tumor suppressor in several human cancer types by regulating EGFR. However, the detailed involvement of miR‑133b and EGFR in CRC cells remain to be elucidated. The present study used reverse transcription quantitative polymerase chain reaction and characterized the downregulation of the expression levels of miR‑133b in CRC tissues and cell lines. Cell functional assays demonstrated that restored expression of miR‑133b inhibited the growth and invasion of CRC cells. In addition, a luciferase reporter assay revealed that miR‑133b directly targeted EGFR and repressed its expression levels in CRC cells. Additionally, combination treatment with miR‑133b mimics and the monoclonal anti‑EGFR antibody, cetuximab, which is approved and frequently used for treating patients with CRC, exhibited improved inhibitory effects on the growth and invasion of CRC cells compared with treatment with either alone. Taken together, the present study characterized the role of the miR‑133b/EGFR interaction in CRC cells and this suggested the combinational therapy with cetuximab and miR‑133b was positive and may be a potential novel treatment for patients with CRC in the future.

[Advances in tumor chemo-resistance regulated by MicroRNA]

Chemotherapy is one of the primary treatment for malignant tumors. Tumor multidrug resistance (MDR) is a major cause of clinical failure of chemotherapy; however the mechanisms of chemo-resistance have not been fully elucidated. Recently, microRNA is one of the new hotspots in life science. MicroRNA regulates the expression of genes and plays roles a series of life events by post-transcriptional regulations, including cell proliferation, apoptosis, fat metabolism, nervous development, hormone secretion, tumor vessels generation, stem cell differentiation, tumor cell invasion and metastasis, and other physiological and pathological processes. Recent studies show that microRNA regulates the expression of multiple genes with high efficiency and specificity. The abnormal regulation of target genes by microRNA is responsible for tumor chemo-resistance, this may be an important component of the complexity of the regulation of chemo-resistance. Therefore, the study of microRNA and tumor drug resistance has profound practical significance. In this review, recent studies of tumor drug resistance, regulation of tumor drug resistance by microRNA, and microRNA as a potential target for tumor drug resistance therapy are reviewed.

Expression profile analysis of microRNAs in prostate cancer by next-generation sequencing

BACKGROUND

Prostate cancer (PCa) is the second leading cause of tumor mortality among males in western societies. In China, the diagnostic and fatality rate of PCa is increasing yearly.

METHODS

To characterize underlying molecular mechanisms, the microRNA (miRNA) profile of high-grade PCa, low-grade PCa, and benign prostate hyperplasia (BPH) were compared using high-throughput Illumina sequencing and quantitative real-time PCR (qRT-PCR) methods. Moreover, a variety of biological information softwares and databases were applied to predict the target genes of miRNA, molecular functions, and signal pathways.

RESULTS

Eighteen miRNAs were differentially expressed (fold change ≥ 2, P < 0.05), of which thirteen were upregulated and five were downregulated by sequencing. This was confirmed by qRT-PCR in more clinical tissue samples. In the tumors, miRNAs (miR-125b-5p, miR-126-5p, miR-151a-5p, miR-221-3p, and miR-222-3p) were significantly upregulated with downregulation of miR-486-5p. In addition, 13 novel miRNAs were identified from three prostate tissue libraries, with 12 of them assayed in 21 human normal tissues by qRT-PCR. Multiple databases indicated target genes for these differentially expressed miRNAs. Function annotation of target genes indicated that most of them tend to target genes involved in signal transduction and cell communication, especially cancer-related PI3K-Akt and p53 signaling pathway.

CONCLUSIONS

The small RNA transcriptomes obtained in this study uncovers six differentially expressed miRNAs and 12 novel miRNAs, and provides a better understanding of the expression and function of miRNAs in the development of PCa and reveals several miRNAs in PCa that may have biomarker and therapeutic potentials.

Expression and prognostic value of miR-486-5p in patients with gastric adenocarcinoma

MicroRNA (miR)-486-5p expression is often reduced in human cancers. However, its expression in gastric carcinoma and its relation to clinicopathological features and prognosis are unclear. Tissue microarrays were constructed from 84 patients with gastric adenocarcinoma (GC) who were undergoing radical resection. miR-486-5p expression was detected by miRNA-locked nucleic acid in situ hybridization, and its correlations with clinicopathological features and overall survival were analyzed. Bioinformatic studies predict that fibroblast growth factor 9 (FGF9) is a potential target gene of miR-486-5p. miR-486-5p was mainly located in the cytoplasm of GC cells and neighboring normal tissues. Compared with paracancerous normal tissue, miR-486-5p expression was decreased in 63.1% (53/84) of the GC samples, increased in 32.1% (27/84) and unchanged in 4.8% (4/84). FGF9 expression was decreased in 69.0% (58/84) of GC samples and increased in 31.0% (26/84) compared with normal paracancerous tissues using immunohistochemical analysis. Low or unchanged miR-486-5p expression (P = 0.002), tumor stage (P = 0.001), tumor status (P = 0.001), node status (P = 0.001), tumor size (P = 0.004), and depth of tumor invasion (P = 0.013) were significant negative prognostic predictors for overall survival in patients with GC. After stratification according to American Joint Committee on Cancer (AJCC) stage, low/unchanged miR-486-5p expression remained a significant predictor of poor survival in stage II (P = 0.024) and stage III (P = 0.003). Cox regression analysis identified the following predictors of poor prognosis: tumor status (hazard ratio [HR], 7.19; 95% confidence interval [CI], 1.75–29.6; P = 0.006), stage (HR, 2.62; 95%CI, 1.50–4.59; P = 0.001), lymph node metastasis (HR, 2.52; 95% CI, 1.27–4.99; P = 0.008), low/unchanged miR-486-5p (HR, 2.47; 95% CI, 1.35–4.52; P = 0.003), high level of FGF9 (HR, 2.41; 95% CI, 1.42–4.09; P = 0.001) and tumor size (HR, 2.50; 95% CI, 1.30–4.82; P = 0.006). Low or unchanged expression of miR-486-5p compared with neighboring normal tissues was associated with a poor prognosis, while high expression was associated with a good prognosis in GC. miR-486-5p may thus be useful for evaluating prognosis and may provide a novel target treatment in patients with GC.

MicroRNA-486 regulates normal erythropoiesis and enhances growth and modulates drug response in CML progenitors

MicroRNAs (miRNAs) are key regulators of hematopoietic cell differentiation and may contribute to altered growth of leukemic stem cells. Using microarray-based miRNA profiling, we found that miRNA 486 (miR-486) is significantly upregulated in chronic myeloid leukemia (CML) compared with normal CD34(+) cells, particularly in the megakaryocyte-erythroid progenitor population. miR-486-5p expression increased during erythroid differentiation of both CML and normal CD34(+) cells. Ectopic miR-486-5p expression enhanced in vitro erythroid differentiation of normal CD34(+) cells, whereas miR-486-5p inhibition suppressed normal CD34(+) cell growth in vitro and in vivo and inhibited erythroid differentiation and erythroid cell survival. The effects of miR-486-5p on hematopoietic cell growth and survival are mediated at least in part via regulation of AKT signaling and FOXO1 expression. Using gene expression and bioinformatics analysis, together with functional screening, we identified several novel miR-486-5p target genes that may modulate erythroid differentiation. We further show that increased miR-486-5p expression in CML progenitors is related to both kinase-dependent and kinase-independent mechanisms. Inhibition of miR-486-5p reduced CML progenitor growth and enhanced apoptosis following imatinib treatment. In conclusion, our studies reveal a novel role for miR-486-5p in regulating normal hematopoiesis and of BCR-ABL-induced miR-486-5p overexpression in modulating CML progenitor growth, survival, and drug sensitivity.

MicroRNAs in colorectal cancer: small molecules with big functions

Colorectal cancer (CRC) is the third most lethal malignancy, with pathogenesis intricately dependent upon microRNAs (miRNAs). miRNAs are short, non-protein coding RNAs, targeting the 3'-untranslated regions (3'-UTR) of certain mRNAs. They usually serve as tumor suppressors or oncogenes, and participate in tumor phenotype maintenance. Therefore, miRNAs consequently regulate CRC carcinogenesis and other biological functions, including apoptosis, development, angiogenesis, migration, and proliferation. Due to its differential expression and distinct stability, miRNAs are regarded as molecular biomarkers (for diagnosis/prognosis) and therapeutic targets for CRC. Recently, a remarkable number of miRNAs have been discovered with implications via incompletely understood mechanisms in CRC. As further study of relevant miRNAs continues, it is hopeful that novel miRNA-based therapeutic strategies may be available for CRC patients in the future.

MicroRNAs as novel predictive biomarkers and therapeutic targets in colorectal cancer

Colorectal cancer (CRC) is the third most common cancer in western countries. Despite significant improvement in available treatment options, CRC still remains the second leading cause of cancer-related death. Traditionally, 5-fluorouracil has been used as the main chemotherapy drug for treatment of metastatic CRC (mCRC). However, during the last two decades more effective chemotherapeutic agents such as oxaliplatin, irinotecan and the monoclonal antibodies cetuximab, panitumumab and bevacizumab have been used in clinical practice. More recently, the therapeutic armamentarium has been supplemented by the monoclonal antibodies bevacizumab, cetuximab and panitumumab as well as the protein-trap aflibercept and the small molecule multi-kinase inhibitor regorafenib. One of the major problems for the management of CRC is the inherent or acquired resistance to therapeutic approaches. The discovery of microRNAs (miRNAs), a class of small, endogenous, non-coding, single-stranded RNAs that play a role as post-transcriptional regulators, has added new dimensions to the diagnosis and treatment of cancer. Because miRNAs are important regulators of carcinogenesis, progression, invasion, angiogenesis and metastases in CRC, they might serve as potential predictive and prognostic factors and even as therapeutic targets themselves. Several miRNAs are already known to be dysregulated in CRCs and have been linked to biological processes involved in tumor progression and response to anti-cancer therapies. This review summarizes current therapeutic approaches for treating CRC and highlights the role of miRNAs as novel predictive biomarkers and potential drug targets in CRC patients.

MiR-107 and miR-99a-3p predict chemotherapy response in patients with advanced colorectal cancer

Background

MicroRNAs (miRNAs) are involved in numerous biological and pathological processes including colorectal cancer (CRC). The aim of our study was to evaluate the ability of miRNA expression patterns to predict chemotherapy response in a cohort of 78 patients with metastatic CRC (mCRC).

Methods

We examined expression levels of 667 miRNAs in the training cohort and evaluated their potential association with relevant clinical endpoints. We identified a miRNA profile that was analysed by RT-qPCR in an independent cohort. For a set of selected miRNAs, bioinformatic target predictions and pathway analysis were also performed.

Results

Eight miRNAs (let-7 g*, miR-107, miR-299-5p, miR-337-5p, miR-370, miR-505*, miR-889 and miR-99a-3p) were significant predictors of response to chemotherapy in the training cohort. In addition, overexpression of miR-107, miR-337-5p and miR-99a-3p, and underexpression of miR-889, were also significantly associated with improved progression-free and/or overall survival. MicroRNA-107 and miR-99a-3p were further validated in an independent cohort as predictive markers for chemotherapy response. In addition, an inverse correlation was confirmed in our study population between miR-107 levels and mRNA expression of several potential target genes (CCND1, DICER1, DROSHA and NFKB1).

Conclusions

MiR-107 and miR-99a-3p were validated as predictors of response to standard fluoropyrimidine-based chemotherapy in patients with mCRC.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-656) contains supplementary material, which is available to authorized users.

MicroRNA-486-5p targeting PIM-1 suppresses cell proliferation in breast cancer cells

MicroRNAs (miRNAs) are emerging as critical regulators in carcinogenesis and tumor progression. Recently, miR-486-5p has been proved to play an important role in several cancers, but its functions in the context of breast cancer (BC) remain unknown. In this study, we found that miR-486-5p expression is significantly downregulated in BC tissues and cell lines. Overexpression of miR-486-5p dramatically suppressed BC cell proliferation in vitro and in vivo, induced G0/G1 arrest, and promoted apoptosis. We subsequently identified the oncogene PIM-1 as a direct target of miR-486-5p in BC. Overexpression of PIM-1 attenuated the function of miR-486-5p in BC cells. Together, we conclude that miR-486-5p exerts its antiproliferative function by directly downregulating PIM-1 expression. This novel miR-486-5p/PIM-1 axis provides insight into the pathogenesis of BC and might be therapeutic targets for prevention or treatment of BC.

Current approaches for predicting a lack of response to anti-EGFR therapy in KRAS wild-type patients

Targeting epidermal growth factor receptor (EGFR) has been one of the most effective colorectal cancer strategies. Anti-EGFR antibodies function by binding to the extracellular domain of EGFR, preventing its activation, and ultimately providing clinical benefit. KRAS mutations in codons 12 and 13 are recognized prognostic and predictive biomarkers that should be analyzed at the clinic prior to the administration of anti-EGFR therapy. However, still an important fraction of KRAS wild-type patients do not respond to the treatment. The identification of additional genetic determinants of primary or secondary resistance to EGFR targeted therapy for further improving the selection of patients is urgent. Herein, we review the latest published literature highlighting the most important genes that may predict resistance to anti-EGFR monoclonal antibodies in colorectal cancer patients. According to the available findings, the evaluation of BRAF, NRAS, PIK3CA, and PTEN status could be the right strategy to select patients who are likely to respond to anti-EGFR therapies. In the future, the combination of those biomarkers will help establish consensus that can be introduced into clinical practice.

Identification of circulating microRNAs for the differential diagnosis of Parkinson's disease and Multiple System Atrophy

Background: Parkinson's disease (PD) is a progressive neurodegenerative disorder which may be misdiagnosed with atypical conditions such as Multiple System Atrophy (MSA), due to overlapping clinical features. MicroRNAs (miRNAs) are small non-coding RNAs with a key role in post-transcriptional gene regulation. We hypothesized that identification of a distinct set of circulating miRNAs (cmiRNAs) could distinguish patients affected by PD from MSA and healthy individuals. Results. Using TaqMan Low Density Array technology, we analyzed 754 miRNAs and found 9 cmiRNAs differentially expressed in PD and MSA patients compared to healthy controls. We also validated a set of 4 differentially expressed cmiRNAs in PD and MSA patients vs. controls. More specifically, miR-339-5p was downregulated, whereas miR-223^*, miR-324-3p, and mir-24 were upregulated in both diseases. We found cmiRNAs specifically deregulated in PD (downregulation of miR-30c and miR-148b) and in MSA (upregulation of miR-148b). Finally, comparing MSA and PD, we identified 3 upregulated cmiRNAs in MSA serum (miR-24, miR-34b, miR-148b). Conclusions. Our results suggest that cmiRNA signatures discriminate PD from MSA patients and healthy controls and may be considered specific, non-invasive biomarkers for differential diagnosis.