Functional Significance and Therapeutic Potential of miRNA-20b-5p in Esophageal Squamous Cell Carcinoma

Non‑coding RNA: A promising diagnostic biomarker and therapeutic target for esophageal squamous cell carcinoma (Review)

Esophageal cancer (EC) is a common form of malignant tumor in the digestive system that is classified into two types: Esophageal squamous cell carcinomas (ESCC) and esophageal adenocarcinoma. ESCC is known for its early onset of symptoms, which can be difficult to identify, as well as its rapid progression and tendency to develop drug resistance to chemotherapy and radiotherapy. These factors contribute to the high incidence of disease and low cure rate. Therefore, a diagnostic biomarker and therapeutic target need to be identified for ESCC. Non-coding RNAs (ncRNAs) are a class of molecules that are transcribed from DNA but do not encode proteins. Initially, ncRNAs were considered to be non-functional segments generated during transcription. However, with advancements in high-throughput sequencing technologies in recent years, ncRNAs have been associated with poor prognosis, drug resistance and progression of ESCC. The present study provides a comprehensive overview of the biogenesis, characteristics and functions of ncRNAs, particularly focusing on microRNA, long ncRNAs and circular RNAs. Furthermore, the ncRNAs that could potentially be used as diagnostic biomarkers and therapeutic targets for ESCC are summarized to highlight their application value and prospects in ESCC.

MicroRNAs: A novel signature in the metastasis of esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is a malignant epithelial tumor, characterized by squamous cell differentiation, it is the sixth leading cause of cancer-related deaths globally. The increased mortality rate of ESCC patients is predominantly due to the advanced stage of the disease when discovered, coupled with higher risk of metastasis, which is an exceedingly malignant characteristic of cancer, frequently leading to a high mortality rate. Unfortunately, there is currently no specific and effective marker to predict and treat metastasis in ESCC. MicroRNAs (miRNAs) are a class of small non-coding RNA molecules, approximately 22 nucleotides in length. miRNAs are vital in modulating gene expression and serve pivotal regulatory roles in the occurrence, progression, and prognosis of cancer. Here, we have examined the literature to highlight the intimate correlations between miRNAs and ESCC metastasis, and show that ESCC metastasis is predominantly regulated or regulated by genetic and epigenetic factors. This review proposes a potential role for miRNAs as diagnostic and therapeutic biomarkers for metastasis in ESCC metastasis, with the ultimate aim of reducing the mortality rate among patients with ESCC.

CircGFPT1 regulates the growth and apoptosis of esophageal squamous cell carcinoma through miR-142-5p/HAX1 axis

BACKGROUND

Currently, multiple circular RNAs (circRNAs) have been verified to act as essential regulators in the progression of esophageal squamous cell carcinoma (ESCC). However, there is no study regarding the role of circGFPT1 in the progression of cancers including ESCC. We aimed to investigate the role of circGFPT1 in ESCC progression.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was utilized to measure the expression of circGFPT1, miR-142-5p and HS1-associated protein X-1 (HAX1). 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) and 5-ethynyl-2'-deoxyuridine (EdU) assays were employed to evaluate cell proliferation. Cell migration and invasion were detected by wound-healing and transwell assays. Flow cytometry analysis was conducted to assess cell apoptosis. The protein expression of E-cadherin, N-cadherin, Vimentin, C-caspase3, HAX1 and nuclear proliferation marker (Ki67) was analyzed by western blot or immunohistochemistry assay.

RESULTS

CircGFPT1 was up-regulated in ESCC tissues and cells. Silencing of circGFPT1 repressed cell proliferation and induced cell apoptosis in ESCC cells. CircGFPT1 acted as a sponge of miR-142-5p. The effects of circGFPT1 knockdown on ESCC cell proliferation and apoptosis were reversed by miR-142-5p inhibition. HAX1 was confirmed to be a target gene of miR-142-5p. CircGFPT1 knockdown inhibited HAX1 expression by targeting miR-142-5p. Additionally, circGFPT1 knockdown hampered tumorigenesis in vivo.

CONCLUSION

CircGFPT1 promoted ESCC cell growth and repressed apoptosis by up-regulating HAX1 through sponging miR-142-5p.

miRNA in head and neck squamous cell carcinomas: promising but still distant future of personalized oncology

Head and neck squamous cell carcinoma is one of the most common and fatal cancers worldwide. Lack of appropriate preventive screening tests, late detection, and high heterogeneity of these tumors are the main reasons for the unsatisfactory effects of therapy and, consequently, unfavorable outcomes for patients. An opportunity to improve the quality of diagnostics and treatment of this group of cancers are microRNAs (miRNAs) - molecules with a great potential both as biomarkers and therapeutic targets. This review aims to present the characteristics of these short non-coding RNAs (ncRNAs) and summarize the current reports on their use in oncology focused on medical strategies tailored to patients' needs.

Optimized workflow to modify microRNA expression in primary human intravascular cells

BACKGROUND

A comprehensive dissection of the role of microRNAs (miRNAs) in gene regulation and subsequent cell functions requires a specific and efficient knockdown or overexpression of the miRNA of interest; these are achieved by transfecting the cell of interest with a miRNA inhibitor or a miRNA mimic, respectively. Inhibitors and mimics of miRNAs with a unique chemistry and/or structural modifications are available commercially and require different transfection conditions. Here, we aimed to investigate how various conditions affect the transfection efficacy of two miRNAs with high and low endogenous expression, miR-15a-5p and miR-20b-5p respectively, in human primary cells.

RESULTS

MiRNA inhibitors and mimics from two commonly used commercial vendors were employed, i.e., mirVana (Thermo Fisher Scientific) and locked nucleic acid (LNA) miRNA (Qiagen). We systematically examined and optimized the transfection conditions of such miRNA inhibitors and mimics to primary endothelial cells and monocytes using either a lipid-based carrier (lipofectamine) for delivery or an unassisted uptake. Transfection of LNA inhibitors with either phosphodiester (PE)- or phosphorothioate (PS)-modified nucleotide bonds, delivered using a lipid-based carrier, efficiently downregulated the expression levels of miR-15a-5p already 24 h following transfection. MirVana miR-15a-5p inhibitor displayed a less efficient inhibitory effect, which was not improved 48 h following a single transfection or two consecutive transfections. Interestingly, LNA-PS miR-15a-5p inhibitor efficiently reduced the levels of miR-15a-5p when delivered without a lipid-based carrier in both ECs and monocytes. When using a carrier, mirVana and LNA miR-15a-5p and miR-20b-5p mimics showed similar efficiency 48 h following transfection to ECs and monocytes. None of the miRNA mimics effectively induced overexpression of the respective miRNA when given to primary cells without a carrier.

CONCLUSION

LNA miRNA inhibitors efficiently downregulated the cellular expression of miRNA, such as miR-15a-5p. Furthermore, our findings suggest that LNA-PS miRNA inhibitors can be delivered in the absence of a lipid-based carrier, whereas miRNA mimics need the aid of a lipid-based carrier to achieve sufficient cellular uptake.

The emerging role of miR-20b in human cancer and other disorders: Pathophysiology and therapeutic implications

miR-20b is a microRNA with diverse and somehow contradictory roles in the pathogenesis of human disorders, especially cancers. It has been known to be a tumor suppressor in colon cancer, renal cell carcinoma, prostate cancer, osteosarcoma and papillary thyroid cancer. In lung cancer and breast cancers, both tumor suppressor and oncogenic effects have been identified for this miRNA. Finally, in T cell leukemia, hepatocellular carcinoma, esophageal squamous cell carcinoma and cervical and gastric cancers, miR-20b is regarded as an oncogenic miRNA. In several types of cancer, dysregulation of miR-20b has been recognized as a predictive marker for patients' survival. Dysregulation of miR-20b has also been recognized in Alzheimer's disease, diabetic retinopathy, myocardial ischemia/infarction, chronic hepatitis B and multiple sclerosis. In the current review, we have summarized the miR-20b targets and related cellular processes. We have also provided a review of participation of this miRNA in different human disorders.

Exploiting the Molecular Basis of Oesophageal Cancer for Targeted Therapies and Biomarkers for Drug Response: Guiding Clinical Decision-Making

Worldwide, oesophageal cancer is the sixth leading cause of deaths related to cancer and represents a major health concern. Sub-Saharan Africa is one of the regions of the world with the highest incidence and mortality rates for oesophageal cancer and most of the cases of oesophageal cancer in this region are oesophageal squamous cell carcinoma (OSCC). The development and progression of OSCC is characterized by genomic changes which can be utilized as diagnostic or prognostic markers. These include changes in the expression of various genes involved in signaling pathways that regulate pathways that regulate processes that are related to the hallmarks of cancer, changes in the tumor mutational burden, changes in alternate splicing and changes in the expression of non-coding RNAs such as miRNA. These genomic changes give rise to characteristic profiles of altered proteins, transcriptomes, spliceosomes and genomes which can be used in clinical applications to monitor specific disease related parameters. Some of these profiles are characteristic of more aggressive forms of cancer or are indicative of treatment resistance or tumors that will be difficult to treat or require more specialized specific treatments. In Sub-Saharan region of Africa there is a high incidence of viral infections such as HPV and HIV, which are both risk factors for OSCC. The genomic changes that occur due to these infections can serve as diagnostic markers for OSCC related to viral infection. Clinically this is an important distinction as it influences treatment as well as disease progression and treatment monitoring practices. This underlines the importance of the characterization of the molecular landscape of OSCC in order to provide the best treatment, care, diagnosis and screening options for the management of OSCC.

Ginsenoside 20(S)-Rg3 suppresses cell viability in esophageal squamous cell carcinoma via modulating miR-324-5p-targeted PSME3

Ginsenoside 20(S)-Rg3 is identified as an active saponin monomer which derived from red ginseng and is demonstrated to play an anti-tumor role in diverse cancers. MicroRNAs (miRNAs) are important regulators in the progression of cancers, containing esophageal squamous cell carcinoma (ESCC). It was reported that microRNA 324-5p (miR-324-5p) exerted critical functions in some cancers; however, the detailed molecular mechanism of miR-324-5p mediated by 20(S)-Rg3 to suppress cell viability in ESCC has not been explored. Herein, we explored the function of 20(S)-Rg3 or miR-324-5p on ESCC cell viability by MTT assay, colony formation assay, flow cytometry analysis and western blot analysis. The binding of miR-324-5p to its target gene, proteasome activator subunit 3 (PSME3), was confirmed through RNA pull down and luciferase reporter assays. The results indicated that 20(S)-Rg3 significantly inhibited cell viability and the cell cycle and facilitated cell apoptosis. Furthermore, this effect was strengthened with the increased concentration of 20(S)-Rg3. Moreover, we found that miR-324-5p level was increased under 20(S)-Rg3 treatment. Additionally, overexpressed miR-324-5p inhibited ESCC cell viability, and downregulated miR-324-5p recovered inhibited cell viability caused by 20(S)-Rg3. Further exploration verified that miR-324-5p targeted PSME3, and PSME3 deficiency countervailed the effect of miR-324-5p inhibition on ESCC cell viability under 20(S)-Rg3 treatment. Conclusively, 20(S)-Rg3 suppresses cell viability in ESCC via mediating miR-324-5p-targeted PSME3.

Host miRNA and immune cell interactions: relevance in nano-therapeutics for human health

Around 2200 miRNA (microRNA) genes were found in the human genome. miRNAs are arranged in clusters within the genome and share the same transcriptional regulatory units. It has been revealed that approximately 50% of miRNAs elucidated in the genome are transcribed from non-protein-coding genes, and the leftover miRNAs are present in the introns of coding sequences. We are now approaching a stage in which miRNA diagnostics and therapies can be established confidently, and several commercial efforts are underway to carry these innovations from the bench to the clinic. MiRNAs control many of the significant cellular activities such as production, differentiation, growth, and metabolism. Particularly in the immune system, miRNAs have emerged as a crucial biological component during diseased state and homeostasis. miRNAs have been found to regulate inflammatory responses and autoimmune disorders. Moreover, each miRNA targets multiple genes simultaneously, making miRNAs promising tools as diagnostic biomarkers and as remedial targets. Still, one of the major obstacles in miRNA-based approaches is the achievement of specific and efficient systemic delivery of miRNAs. To overcome these challenges, nanoformulations have been synthesized to protect miRNAs from degradation and enhance cellular uptake. The current review deals with the miRNA-mediated regulation of the recruitment and activation of immune cells, especially in the tumor microenvironment, viral infection, inflammation, and autoimmunity. The nano-based miRNA delivery modes are also discussed here, especially in the context of immune modulation.

MiRNA-20b/SUFU/Wnt axis accelerates gastric cancer cell proliferation, migration and EMT

Previous research has found that miRNA-20b is highly expressed in gastric cancer (GC), however, its function and underlying mechanism are not clear. Wnt signaling pathway, implicated in tumorigeneisis, is activated in more than 30% of GC. We would like to characterize the biological behavior of miRNA-20b in terms of modulating Wnt/β-catenin signaling and EMT. We showed that miRNA-20b inhibitors suppressed Topflash/Fopflash dependent luciferase activity and the β-catenin nuclear translocation, resulting in inhibition of Wnt pathway activity and EMT. SUFU, negatively regulating Wnt and Hedgehog signaling pathway, was proved to be targeted by miRNA-20b. Moreover, additional knockdown of SUFU alleviated the inhibitory effect on Wnt pathway activity, EMT, cell proliferation/migration and colony formation caused by miRNA-20b inhibition. In summary, miRNA-20b is an oncogenic miRNA and promoted cell proliferation, migration and EMT in GC partially by activating Wnt pathway via targeting SUFU.

Epigenetic Regulation of MicroRNA Clusters and Families during Tumor Development

MicroRNAs are small non-coding single-stranded RNA molecules regulating gene expression on a post-transcriptional level based on the seed sequence similarity. They are frequently clustered; thus, they are either simultaneously transcribed into a single polycistronic transcript or they may be transcribed independently. Importantly, microRNA families that contain the same seed region and thus target related signaling proteins, may be localized in one or more clusters, which are in a close relationship. MicroRNAs are involved in basic physiological processes, and their deregulation is associated with the origin of various pathologies, including solid tumors or hematologic malignancies. Recently, the interplay between the expression of microRNA clusters and families and epigenetic machinery was described, indicating aberrant DNA methylation or histone modifications as major mechanisms responsible for microRNA deregulation during cancerogenesis. In this review, the most studied microRNA clusters and families affected by hyper- or hypomethylation as well as by histone modifications are presented with the focus on particular mechanisms. Finally, the diagnostic and prognostic potential of microRNA clusters and families is discussed together with technologies currently used for epigenetic-based cancer therapies.

Polygalacin D suppresses esophageal squamous cell carcinoma growth and metastasis through regulating miR-142-5p/Nrf2 axis

Esophageal squamous cell carcinoma (ESCC) is a common malignancy worldwide with poor survival. High expression of nuclear factor erythroid 2-related factor 2 (Nrf2) is an antioxidant transcript factor that protects malignant cells from death. Polygalacin D (PGD), a bioactive compound isolated from Platycodongrandiflorum (Jacq.), has recently been reported to be an anti-tumor agent. This study aimed to investigate the anti-cancer effects of PGD and its underlying molecular mechanisms in human ESCC. Here, we confirmed that Nrf2 was over-expressed in clinical ESCC tissues and cell lines. PGD treatments markedly reduced Nrf2 expression in a dose- and time-dependent manner in ESCC cell lines. Importantly, we found that PGD significantly reduced proliferation, and induced G2/M cell cycle arrest and apoptosis in ESCC cells. Also, PGD dramatically triggered autophagy in ESCC cells, and autophagy inhibitor bafilomycinA1 (BafA1) greatly abrogated the inhibitory role of PGD in cell viability and apoptosis. In addition, PGD evidently provoked reactive oxygen species (ROS) accumulation in ESCC cells, and pre-treatment of ROS scavenger N-acetyl-l-cysteine (NAC) markedly abolished PGD-triggered cell death. PGD also dramatically repressed migration and invasion in ESCC cells. Mechanistic investigation revealed that Nrf2 gene was directly targeted by miR-142-5p. MiR-142-5p negatively regulated Nrf2 expression in ESCC cells. We notably found that PGD-inhibited proliferation, migration and invasion in ESCC were considerably rescued by miR-142-5p knockdown; however, ROS production, apoptosis and autophagy induced by PGD were almost eliminated when miR-142-5p was silenced. On the contrast, over-expressing miR-142-5p could remarkably promote the anti-ESCC effects of PGD. Experiments in vivo by the tumor xenograft model confirmed that miR-142-5p effectively improved the activity of PGD to repress tumor growth and lung metastasis. Both in vitro and in vivo studies showed that PGD had few side effects on normal cells and major organs. Collectively, our findings provided the first evidence that PGD could be an effective therapeutic strategy for ESCC treatment by regulating miR-142-5p/Nrf2 axis with few adverse effects.

Four circulating exosomal miRNAs as novel potential biomarkers for the early diagnosis of human colorectal cancer

Colorectal cancer (CRC) is the second leading cause of cancer-related deaths worldwide. Our study aimed to identify novel circulating miRNAs as early diagnostic biomarkers of CRC. The Gene Expression Omnibus (GEO) datasets were analyzed by using the online tool GEO2R. Isolated exosomes were verified by using the transmission electron microscope (TEM), Nanosight, and western blot. qRT-PCR was implemented to examine miRNA expression. The diagnostic value of circulating exosomal miRNAs was identified by using the receiver operating characteristic curve (ROC). In this study, we found that serum exosomal miRNAs are more suitable for diagnosing CRC when compared to serum miRNAs. Furthermore, we identified four exosomal miRNAs (miR-126, miR-1290, miR-23a, and miR-940) in the serum of CRC patients as novel potential biomarkers for the early diagnosis of CRC because they showed high diagnostic values to differentiate CRC patients at TNM stage I from healthy controls (HCs). In addition, our data suggested that CRC cells may secrete miRNAs into the extracellular environment through exosomes regardless of intracellular miRNA expression. In conclusion, we identified serum exosomal miR-126, miR-1290, miR-23a, and miR-940 as novel potential biomarkers for the early diagnosis of CRC.