MiR-19b/20a/92a regulates the self-renewal and proliferation of gastric cancer stem cells

Extracellular Vesicle miRNAs in Diagnostics of Gastric Cancer

Gastric cancer (GC) poses a significant global health challenge because of its high mortality rate attributed to the late-stage diagnosis and lack of early symptoms. Early cancer diagnostics is crucial for improving the survival rates in GC patients, which emphasizes the importance of identifying GC markers for liquid biopsy. The review discusses a potential use of extracellular vesicle microRNAs (EV miRNAs) as biomarkers for the diagnostics and prognostics of GC. Methods. Original articles on the identification of EV miRNA as GC markers published in the Web of Science and Scopus indexed issues were selected from the PubMed and Google Scholar databases. We focused on the methodological aspects of EV analysis, including the choice of body fluid, methods for EV isolation and validation, and approaches for EV miRNA analysis. Conclusions. Out of 33 found articles, the majority of authors investigated blood-derived extracellular vesicles (EVs); only a few utilized EVs from other body fluids, including tissue-specific local biofluids (washing the tumor growth areas), which may be a promising source of EVs in the context of cancer diagnostics. GC-associated miRNAs identified in different studies using different methods of EV isolation and analysis varied considerably. However, three miRNAs (miR-10b, miR-21, and miR-92a) have been found in several independent studies and shown to be associated with GC in experimental models. Further studies are needed to determine the optimal miRNA marker panel. Another essential step necessary to improve the reliability and reproducibility of EV-based diagnostics is standardization of methodologies for EV handling and analysis of EV miRNA.

Genetic Factors and MicroRNAs in the Development of Gallbladder Cancer: The Prospective Clinical Targets

Gallbladder cancer (GBC) is an uncommon condition in which malignant (cancer) cells are detected in gallbladder tissue. Cancer is often triggered when normal cells turn malignant and begin to spread. Cancer can also be caused by genetic anomalies that result in uncontrolled cell proliferation and tumor development. MicroRNAs (also known as miRNAs or miRs) are a group of small, endogenous, non-coding RNAs of 19-23 nucleotides in length, which play a key role in post-transcriptional gene regulation. These miRNAs serve as negative gene regulators by supervising target genes and regulating biological processes, including cell proliferation, migration, invasion, and apoptosis. Cancer development and progression relate to aberrant miRNA expression. This review demonstrated the implication of various genetic factors and microRNAs in developing and regulating GBC. This suggests the potential of genes and RNAs as the diagnostic, prognostic, and therapeutic targets in gallbladder cancer.

HIPK1 Inhibition Protects against Pathological Cardiac Hypertrophy by Inhibiting the CREB-C/EBPβ Axis

Inhibition of pathological cardiac hypertrophy is recognized as an important therapeutic strategy for heart failure, although effective targets are still lacking in clinical practice. Homeodomain interacting protein kinase 1 (HIPK1) is a conserved serine/threonine kinase that can respond to different stress signals, however, whether and how HIPK1 regulates myocardial function is not reported. Here, it is observed that HIPK1 is increased during pathological cardiac hypertrophy. Both genetic ablation and gene therapy targeting HIPK1 are protective against pathological hypertrophy and heart failure in vivo. Hypertrophic stress-induced HIPK1 is present in the nucleus of cardiomyocytes, while HIPK1 inhibition prevents phenylephrine-induced cardiomyocyte hypertrophy through inhibiting cAMP-response element binding protein (CREB) phosphorylation at Ser271 and inactivating CCAAT/enhancer-binding protein β (C/EBPβ)-mediated transcription of pathological response genes. Inhibition of HIPK1 and CREB forms a synergistic pathway in preventing pathological cardiac hypertrophy. In conclusion, HIPK1 inhibition may serve as a promising novel therapeutic strategy to attenuate pathological cardiac hypertrophy and heart failure.

Oncogenic role of microRNA-19b-3p-mediated SOCS3 in glioma through activation of JAK-STAT pathway

The altered expression of microRNA (miRNA) has been implicated in glioma. Here, the current study aimed to clarify the oncogenic effects of miR-19b-3p on cellular processes of glioma and to elucidate the underlying mechanism associated with SOCS3 and the JAK-STAT signaling pathway. Differentially expressed genes related to glioma were initially identified via microarray analysis. Twenty-five glioma patients were selected for clinical data collection, while additional 12 patients with traumatic brain injuries were selected as controls. Cell senescence was assessed by β-galactosidase staining, proliferation by MTT assay and apoptosis by flow cytometry following gain- and/or loss-of-function of miR-19b-3p or SOCS3. Glioma xenograft mouse model was developed through subcutaneous injection to nude mice to provide evidence in vivo. The glioma patients exhibited overexpressed miR-19b-3p and poorly-expressed SOCS3. SOCS3 was identified as a target gene of miR-19b-3p through dual-luciferase reporter gene assay. miR-19b-3p repressed SOCS3 expression and activated the JAK-STAT signaling pathway. Furthermore, miR-19b-3p inhibition promoted apoptosis and senescence, and suppressed cell proliferation through inactivation of the JAK-STAT signaling pathway and up-regulation of SOCS3. The reported regulatory axis was validated in nude mice as evidenced by suppressed tumor growth. Taken together, this study demonstrates that miR-19b-3p facilitates glioma progression via activation of the JAK-STAT signaling pathway by targeting SOCS3, highlighting a novel therapeutic target for glioma treatment.

Synthetic flavagline derivative 1-chloroacetylrocaglaol promotes apoptosis in K562 erythroleukemia cells through miR-17-92 cluster genes

Chronic myeloid leukemia accounts for human deaths worldwide and could enhance sevenfold by 2050. Thus, the treatment regimen for this disorder is highly crucial at this time. Flavaglines are a natural class of cyclopentane benzofurans exhibiting various bioactivities like anticancer action. Despite the antiproliferative activity of flavaglines against diverse cancer cells, their roles and mechanism of action in chronic myeloid leukemia (CML) remain poorly understood. Thus, this study examines the antiproliferative effect of a newly synthesized flavagline derivative, 1-chloracetylrocaglaol (A2074), on erythroleukemia K562 cells and the zebrafish xenograft model. The study revealed that A2074 could inhibit proliferation, promote apoptosis, and boost megakaryocyte differentiation of K562 cells. This flavagline downregulated c-MYC and miR-17-92 cluster genes, targeting upregulation of the apoptotic protein Bcl-2-like protein 11 (BIM). The work uncovered a critical role of the c-MYC-miR-17-92-BIM axis in the growth and survival of CML cells.

The Potential Role of CDH1 as an Oncogene Combined With Related miRNAs and Their Diagnostic Value in Breast Cancer

BACKGROUND

Breast cancer (BC) is the leading cause of cancer-related mortality in females and the most common malignancy with high morbidity worldwide. It is imperative to develop new biomarkers and therapeutic targets for early diagnosis and effective treatment in BC.

METHODS

We revealed the oncogene function of cadherin 1 (CDH1) via bioinformatic analysis in BC. Moreover, miRNA database was utilized to predict miRNAs upstream of CDH1. Expression of CDH1-related miRNAs in BC and their values in BC stemness and prognosis were analyzed through TCGA-BRCA datasets. In addition, Gene Ontology (GO) and Gene Set Enrichment Analysis (GSEA) were performed to explore the potential functions and signaling pathways of CDH1 in combination with CDH1-related miRNAs in BC progression. Finally, the differential expressions of soluble E-cadherin (sE-cad), which is formed by the secretion of CDH1-encoded E-cadherin into serum, analyzed by enzyme-linked immunosorbent assay (ELISA). Reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) was used to detect the expression level of CDH1-related miRNAs in serum samples.

RESULTS

The mRNA and protein expressions of CDH1 were elevated in BC tissues compared with normal counterparts. Moreover, CDH1 overexpression was positively correlated with BC stage, metastatic, stemness characteristics, and poor prognosis among patients. In predictive analysis, miR-340, miR-185, and miR-20a target CDH1 and are highly expressed in BC. miR-20a overexpression alone was strongly associated with high stemness characteristics and poor prognosis of BC. Additionally, GO, KEGG, and hallmark effect gene set analysis demonstrated that CDH1 in combination with overexpression of miR-340, miR-185, or miR-20a participated in multiple biological processes and underly signaling pathways involving in tumorigenesis and development of BC. Finally, we provide experimental evidence that the combined determination of serum sE-cad and miR-20a in BC has highly diagnostic efficiency.

CONCLUSIONS

This study provides evidence for CDH1 as an oncogene in BC and suggests that miR-20a may regulate the stemness characteristics of BC to exert a pro-oncogenic effect by regulating CDH1. Moreover, sE-cad and miR-20a in serum can both be used as valid noninvasive markers for BC diagnosis.

Emerging Role of E2F Family in Cancer Stem Cells

The E2F family of transcription factors (E2Fs) consist of eight genes in mammals. These genes encode ten proteins that are usually classified as transcriptional activators or transcriptional repressors. E2Fs are important for many cellular processes, from their canonical role in cell cycle regulation to other roles in angiogenesis, the DNA damage response and apoptosis. A growing body of evidence demonstrates that cancer stem cells (CSCs) are key players in tumor development, metastasis, drug resistance and recurrence. This review focuses on the role of E2Fs in CSCs and notes that many signals can regulate the activities of E2Fs, which in turn can transcriptionally regulate many different targets to contribute to various biological characteristics of CSCs, such as proliferation, self-renewal, metastasis, and drug resistance. Therefore, E2Fs may be promising biomarkers and therapeutic targets associated with CSCs pathologies. Finally, exploring therapeutic strategies for E2Fs may result in disruption of CSCs, which may prevent tumor growth, metastasis, and drug resistance.

Current understanding of epigenetics mechanism as a novel target in reducing cancer stem cells resistance

At present, after extensive studies in the field of cancer, cancer stem cells (CSCs) have been proposed as a major factor in tumor initiation, progression, metastasis, and recurrence. CSCs are a subpopulation of bulk tumors, with stem cell-like properties and tumorigenic capabilities, having the abilities of self-renewal and differentiation, thereby being able to generate heterogeneous lineages of cancer cells and lead to resistance toward anti-tumor treatments. Highly resistant to conventional chemo- and radiotherapy, CSCs have heterogeneity and can migrate to different organs and metastasize. Recent studies have demonstrated that the population of CSCs and the progression of cancer are increased by the deregulation of different epigenetic pathways having effects on gene expression patterns and key pathways connected with cell proliferation and survival. Further, epigenetic modifications (DNA methylation, histone modifications, and RNA methylations) have been revealed to be key drivers in the formation and maintenance of CSCs. Hence, identifying CSCs and targeting epigenetic pathways therein can offer new insights into the treatment of cancer. In the present review, recent studies are addressed in terms of the characteristics of CSCs, the resistance thereof, and the factors influencing the development thereof, with an emphasis on different types of epigenetic changes in genes and main signaling pathways involved therein. Finally, targeted therapy for CSCs by epigenetic drugs is referred to, which is a new approach in overcoming resistance and recurrence of cancer.

Recent advances of miRNAs in the development and clinical application of gastric cancer

Gastric cancer (GC) is one of the most common malignant tumors. The mechanism of how GC develops is vague, and therapies are inefficient. The function of microRNAs (miRNAs) in tumorigenesis has attracted the attention from many scientists. During the development of GC, miRNAs function in the regulation of different phenotypes, such as proliferation, apoptosis, invasion and metastasis, drug sensitivity and resistance, and stem-cell-like properties. MiRNAs were evaluated for use in diagnostic and prognostic predictions and exhibited considerable accuracy. Although many problems exist for the application of therapy, current studies showed the antitumor effects of miRNAs. This paper reviews recent advances in miRNA mechanisms in the development of GC and the potential use of miRNAs in the diagnosis and treatment of GC.

miR-34a mimic or pre-mir-34a, which is the better option for cancer therapy? KatoIII as a model to study miRNA action in human gastric cancer cells

Background

Aberrantly expressed microRNAs play important roles in gastric tumorigenesis. However, use of miRNAs as a therapeutic option in gastric cancer still remains as a challenging problem.

Methods

We performed transient transfection of miR-34a-5p mimic and stable transfection of pre-mir-34a into KatoIII cells. Then, we evaluated the effect of transfected miRNAs on numerous cellular and molecular processes.

Results

Following transient transfection of miR-34a-5p mimic at 25 nM—a commonly used concentration—into KatoIII cells, inhibition of two target genes expression, namely Notch1 and β-catenin, was not observed, but a non-significant marginal increase of these genes was detected. No changes were detected in the percentage of apoptotic cells as well as in CD44 + and EpCAM + cells after 25 nM miR-34a-5p mimic transfection. Interestingly, stable transfection of pre-mir-34a into KatoIII cells (named as KatoIII-pGFPC1-34a cells) caused a significant repression in β-catenin protein and Notch1 mRNA levels (p < 0.05 and p < 0.01, respectively) relative to equivalent control (KatoIII- pGFPC1-empty cells). The percentage of CD44 + cells in the KatoIII-pGFPC1-34a cells (< 40%) was significantly lower than that in control cells (~ 95%) (p < 0.05). An increase of ~ 3.5% in apoptotic cells and a slower proliferation rate were detected in KatoIII-pGFPC1-34a cells.

Conclusions

Our study revealed that the effect of miR mimic in target gene repression can be dependent to its concentration as well as to the cell type. Meanwhile, our findings further support a regulatory function for pre-miRNAs in target repression and will help to develop effective therapeutic strategies in cancer treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-01872-5.

The role of hypoxia in the tumor microenvironment and development of cancer stem cell: a novel approach to developing treatment

Hypoxia is a common feature of solid tumors, and develops because of the rapid growth of the tumor that outstrips the oxygen supply, and impaired blood flow due to the formation of abnormal blood vessels supplying the tumor. It has been reported that tumor hypoxia can: activate angiogenesis, thereby enhancing invasiveness and risk of metastasis; increase survival of tumor, as well as suppress anti-tumor immunity and hamper the therapeutic response. Hypoxia mediates these effects by several potential mechanisms: altering gene expression, the activation of oncogenes, inactivation of suppressor genes, reducing genomic stability and clonal selection. We have reviewed the effects of hypoxia on tumor biology and the possible strategiesto manage the hypoxic tumor microenvironment (TME), highlighting the potential use of cancer stem cells in tumor treatment.

microRNAs Promoting Growth of Gastric Cancer Xenografts and Correlation to Clinical Prognosis

The annual death toll for gastric cancer is in the range of 700,000 worldwide. Even in patients with early-stage gastric cancer recurrence within five years has been observed after surgical resection and following chemotherapy with therapy-resistant features. Therefore, the identification of new targets and treatment modalities for gastric cancer is of paramount importance. In this review we focus on the role of microRNAs with documented efficacy in preclinical xenograft models with respect to growth of human gastric cancer cells. We have identified 31 miRs (-10b, -19a, -19b, -20a, -23a/b, -25, -27a-3p, -92a, -93, -100, -106a, -130a, -135a, -135b-5p, -151-5p, -187, -199-3p, -215, -221-3p, -224, -340a, -382, -421, -425, -487a, -493, -532-3p, -575, -589, -664a-3p) covering 26 different targets which promote growth of gastric cancer cells in vitro and in vivo as xenografts. Five miRs (miRs -10b, 151-5p, -187, 532-3p and -589) additionally have an impact on metastasis. Thirteen of the identified miRs (-19b, -20a/b, -25, -92a, -106a, -135a, -187, -221-3p, -340a, -421, -493, -575 and -589) have clinical impact on worse prognosis in patients.

The microRNA-17 ~ 92 Family as a Key Regulator of Neurogenesis and Potential Regenerative Therapeutics of Neurological Disorders

miR-17 ~ 92, an miRNA family containing three paralogous polycistronic clusters, was initially considered as an oncogene and was later demonstrated to trigger various physiological and pathological processes. Emerging evidence has implicated miR-17 ~ 92 family as a master regulator of neurogenesis. Through targeting numerous genes that affect cell cycle arrest, stemness deprivation, and lineage commitment, miR-17 ~ 92 family controls the proliferation and neuronal differentiation of neural stem/progenitor cells in both developmental and adult brains. Due to the essential roles of miR-17 ~ 92 family, its misexpression is widely associated with acute and chronic neurological disorders by attenuating neurogenesis and facilitating neuronal apoptosis. The promising neurogenic potential of miR-17 ~ 92 family also makes it a promising “medicine” to activate the endogenous and exogenous regenerative machinery, thus enhance tissue repair and function recovery after brain injury. In this review, we focus on the recent progress made toward understanding the involvement of miR-17 ~ 92 family in regulating both developmental and adult neurogenesis, and discuss the regenerative potential of miR-17 ~ 92 family in treating neurological disorders.

The long non‑coding RNA CASC7 inhibits growth and invasion of non‑small cell lung cancer cells through phosphatase and tensin homolog upregulation via sequestration of miR‑92a

Accumulating evidence has demonstrated the crucial roles of long non-coding RNAs (lncRNAs) in various human cancers, including non-small cell lung cancer (NSCLC). However, to the best of our knowledge, the role of the lncRNA cancer susceptibility candidate 7 (CASC7) in NSCLC has not been clearly determined. The aim of the present study was to investigate the involvement of CASC7 in NSCLC. Marked downregulation of CASC7 was observed in NSCLC tissues and cell lines, and this downregulation of CASC7 was closely associated with distant metastasis, lymph node involvement and poor overall survival in NSCLC patients. Furthermore, overexpression of CASC7 significantly suppressed the proliferation, invasion and migration of the NSCLC cells A549 and H358, and promoted cell apoptosis in vitro. In addition, CASC7 was shown to act as a competing endogenous RNA by sponging miR-92a, which was proven to be an oncogenic miRNA in our previous study. The expression of miR-92a was upregulated in NSCLC tissues and cell lines, and was found to be inversely associated with CASC7 expression in NSCLC tissues. It was also demonstrated that CASC7 upregulated the expression of the tumor suppressor gene phosphatase and tensin homolog (a well-known target of miR-92a) by sequestration of miR-92a. Moreover, the tumor-suppressive effects of CASC7 were partly reversed by miR-92a overexpression in NSCLC cells. Collectively, the results of the present study indicated that CASC7 may act as a tumor-suppressive lncRNA that inhibits NSCLC progression by sponging miR-92a. These findings may improve our understanding of the potential mechanisms through which gain of CASC7 expression represses NSCLC progression.

MicroRNA Expression Profiling of Normal and Malignant Human Colonic Stem Cells Identifies miRNA92a as a Regulator of the LRIG1 Stem Cell Gene

MicroRNAs (miRNAs) have a critical role in regulating stem cells (SCs) during development, and because aberrant expression of miRNAs occurs in various cancers, our goal was to determine if dysregulation of miRNAs is involved in the SC origin of colorectal cancer (CRC). We previously reported that aldehyde dehydrogenase (ALDH) is a marker for normal and malignant human colonic SCs and tracks SC overpopulation during colon tumorigenesis. MicroRNA expression was studied in ALDH-positive SCs from normal and malignant human colon tissues by Nanostring miRNA profiling. Our findings show that: (1) A unique miRNA signature distinguishes ALDH-positive CRC cells from ALDH-positive normal colonic epithelial cells, (2) Expression of four miRNAs (miRNA200c, miRNA92a, miRNA20a, miRNA93) are significantly altered in CRC SCs compared to normal colonic SCs, (3) miRNA92a expression is also upregulated in ALDH-positive HT29 CRC SCs as compared to ALDH-negative SCs, (4) miRNA92a targets the 3′UTR of LRIG1 SC gene, and (5) miRNA92a modulates proliferation of HT29 CRC cells. Thus, our findings indicate that overexpression of miRNA92a contributes to the SC origin of CRC. Strategies designed to modulate miRNA expression, such as miRNA92a, may provide ways to target malignant SCs and to develop more effective therapies against CRC.

Extracellular vesicle-mediated crosstalk between NPCE cells and TM cells result in modulation of Wnt signalling pathway and ECM remodelling

Primary open-angle glaucoma is a leading cause of irreversible blindness, often associated with increased intraocular pressure. Extracellular vesicles (EVs) carry a specific composition of proteins, lipids and nucleotides have been considered as essential mediators of cell-cell communication. Their potential impact for crosstalk between tissues responsible for aqueous humour production and out-flow is largely unknown. The study objective was to investigate the effects of EVs derived from non-pigmented ciliary epithelium (NPCE) primary cells on the expression of Wnt proteins in a human primary trabecular meshwork (TM) cells and define the mechanism underlying exosome-mediated regulation that signalling pathway. Consistent with the results in TM cell line, EVs released by both primary NPCE cells and NPCE cell line showed diminished pGSK3β phosphorylation and decreased cytosolic levels of β-catenin in primary TM cells. At the molecular level, we showed that NPCE exosome treatment downregulated the expression of positive GSKβ regulator-AKT protein but increased the levels of GSKβ negative regulator-PP2A protein in TM cells. NPCE exosome protein analysis revealed 584 miRNAs and 182 proteins involved in the regulation of TM cellular processes, including WNT/β-catenin signalling pathway, cell adhesion and extracellular matrix deposition. We found that negative modulator of Wnt signalling miR-29b was abundant in NPCE exosomal samples and treatment of TM cells with NPCE EVs significantly decreased COL3A1 expression. Suggesting that miR-29b can be responsible for decreased levels of WNT/β-catenin pathway. Overall, this study highlights a potential role of EVs derived from NPCE cells in modulating ECM proteins and TM canonical Wnt signalling.

Hsa_circ_0001649 restrains gastric carcinoma growth and metastasis by downregulation of miR-20a

Background

Gastric carcinoma (GC) is a familiar carcinoma and serious threat to human health. We investigated the efficacy and mechanism of circular RNA hsa_circ_0001649 on the growth, migration, and invasion of GC cells.

Methods

microRNA (miR)‐20a and hsa_circ_0001649 expression was investigated by RT‐qPCR and was changed by cell transfection. CCK‐8, flow cytometry, and BrdU assays were, respectively, used to investigate the efficacies of hsa_circ_0001649 and miR‐20a on cell viability, apoptosis, and proliferation. Transwell assay was used to investigate the efficacies of hsa_circ_0001649 and miR‐20a on cell migration and invasion. Moreover, the levels of cyclin D1, Bax, cleaved caspase‐3, and signal pathway‐related proteins were investigated by Western blot.

Results

Hsa_circ_0001649 was downregulated in GC cells and tissues. Upregulation of hsa_circ_0001649 restrained viability, proliferation, migration, and invasion, while promoted apoptosis. Furthermore, miR‐20a was negatively regulated by hsa_circ_0001649 and miR‐20a overexpression reversed the efficacy of hsa_circ_0001649 upregulation. Finally, upregulation of hsa_circ_0001649 restrained ERK and Wnt/β‐catenin pathways while miR‐20a overexpression reversed these progresses.

Conclusion

Upregulation of hsa_circ_0001649 restrained GC cell growth and metastasis by downregulating miR‐20a and thereby inactivated ERK and Wnt/β‐catenin pathways.

MicroRNA-598 inhibits the growth and maintenance of gastric cancer stem-like cells by down-regulating RRS1

Emerging evidence has identified the critical role of microRNAs in gastric cancer (GC). Herein, this study intends to characterize the tumor suppressive role of microRNA-598 (miR-598) in GC stem-like cells, with the involvement of RRS1. The CD133+ GC stem-like cells were sorted by flow cytometry, after which immunofluorescence assay was used to determine the co-localization of CD133 and CD44v8-10. The miR-598 expression was examined in the CD133+ and CD133- cells. Subsequently, the CD133+ cells were subjected to miR-598 mimics, miR-598 inhibitors or RRS1 siRNA to validate the effect of miR-598 on GC stem-like cell proliferation, colony formation, apoptosis, migration and invasion capacities. Besides, the effect of miR-598 on the expression of key factors (OCT4, SOX2 and NANOG) associated with stem cell characteristics was measured. The obtained results indicated that the sphere forming capacity was higher in CD133+ cells. CD133+ MKN-45 cells expressed CD133 and CD44v8-10, and were expressed on the cell membrane. MiR-598 was poorly expressed in CD133+ cells. Notably, miR-598 negatively regulated RRS1. In response to miR-598 mimics and RRS1 siRNA, the MKN-45 cells displayed inhibited proliferation, colony formation, migration and invasion, accompanied by elevated apoptosis. Besides, the miR-598 inhibitors reversed the situation. This study highlights that miR-598 a tumor suppressor in GC stem-like cells by inhibiting RRS1, whereby miR-598 represses MKN-45 cell growth and invasion by attenuating self-renewal of GC stem-like cells.

Role of miRNA-Regulated Cancer Stem Cells in the Pathogenesis of Human Malignancies

Recent biomedical discoveries have revolutionized the concept and understanding of carcinogenesis, a complex and multistep phenomenon which involves accretion of genetic, epigenetic, biochemical, and histological changes, with special reference to MicroRNAs (miRNAs) and cancer stem cells (CSCs). miRNAs are small noncoding molecules known to regulate expression of more than 60% of the human genes, and their aberrant expression has been associated with the pathogenesis of human cancers and the regulation of stemness features of CSCs. CSCs are the small population of cells present in human malignancies well-known for cancer resistance, relapse, tumorigenesis, and poor clinical outcome which compels the development of novel and effective therapeutic protocols for better clinical outcome. Interestingly, the role of miRNAs in maintaining and regulating the functioning of CSCs through targeting various oncogenic signaling pathways, such as Notch, wingless (WNT)/β-Catenin, janus kinases/ signal transducer and activator of transcription (JAK/STAT), phosphatidylinositol 3-kinase/ protein kinase B (PI3/AKT), and nuclear factor kappa-light-chain-enhancer of activated B (NF-kB), is critical and poses a huge challenge to cancer treatment. Based on recent findings, here, we have documented the regulatory action or the underlying mechanisms of how miRNAs affect the signaling pathways attributed to stemness features of CSCs, such as self-renewal, differentiation, epithelial to mesenchymal transition (EMT), metastasis, resistance and recurrence etc., associated with the pathogenesis of various types of human malignancies including colorectal cancer, lung cancer, breast cancer, head and neck cancer, prostate cancer, liver cancer, etc. We also shed light on the fact that the targeted attenuation of deregulated functioning of miRNA related to stemness in human carcinogenesis could be a viable approach for cancer treatment.

A more physiological approach to lipid metabolism alterations in cancer: CRC-like organoids assessment

Precision medicine might be the response to the recent questioning of the use of metformin as an anticancer drug in colorectal cancer (CRC). Thus, in order to establish properly its benefits, metformin application needs to be assayed on the different progression stages of CRC. In this way, intestinal organoids imply a more physiological tool, representing a new therapeutic opportunity for CRC personalized treatment to assay tumor stage-dependent drugs. The previously reported lipid metabolism-related axis, Acyl-CoA synthetases/ Stearoyl-CoA desaturase (ACSLs/SCD), stimulates colon cancer progression and metformin is able to rescue the invasive and migratory phenotype conferred to cancer cells upon this axis overexpression. Therefore, we checked ACSL/SCD axis status, its regulatory miRNAs and the effect of metformin treatment in intestinal organoids with the most common acquired mutations in a sporadic CRC (CRC-like organoids) as a model for specific and personalized treatment. Despite ACSL4 expression is upregulated progressively in CRC-like organoids, metformin is able to downregulate its expression, especially in the first two stages (I, II). Besides, organoids are clearly more sensitive in the first stage (Apc mutated) to metformin than current chemotherapeutic drugs such as fluorouracil (5-FU). Metformin performs an independent "Warburg effect" blockade to cancer progression and is able to reduce crypt stem cell markers expression such as LGR5+. These results suggest a putative increased efficiency of the use of metformin in early stages of CRC than in advanced disease.

miR-19 family: A promising biomarker and therapeutic target in heart, vessels and neurons

The miR-19 family, including miR-19a, miR-19b-1 and miR-19b-2, arises from two different paralogous clusters miR-17-92 and miR-106a-363. Although it is identified as oncogenic miRNA, the miR-19 family has also been found to play important roles in regulating normal tissue development. The precise control of miR-19 family level is essential for keeping tissue homeostasis and normal development of organisms. Its dysregulation leads to dysplasia, disease and even cancer. Therefore, this review focuses on the roles of miR-19 family in the development and disease of heart, vessels and neurons to estimate the potential value of miR-19 family as diagnostic biomarker or therapeutic target of cardiac, neurological, and vascular diseases.

Up-regulated lncRNA5322 elevates MAPK1 to enhance proliferation of hair follicle stem cells as a ceRNA of microRNA-19b-3p

Hair follicle stem cells (HFSCs), located in the bulge region of the follicle, maintain hair follicle growth and cycling. Long non-coding RNAs (lncRNAs), non-protein coding transcripts, are widely known to play critical roles in differentiation and proliferation of stem cells. Therefore, the current study aimed to explore the regulatory roles of lncRNA5322 in HFSCs proliferation and the underlying regulatory mechanisms. Initially, the expression patterns of lncRNA5322 and microRNA-19b-3p (miR-19b-3p) in HFSCs were detected. Subsequently, gain-and loss-of-functions analyses were conducted to explore the roles of lncRNA5322, miR-19b-3p and mitogen-activated protein kinase 1 (MAPK1) in cell proliferation, colony formation and apoptosis of HFSCs, with the expression of cyclin-dependent kinase (CDK)1 and CDK2 examined. Also, the interaction relationships among lncRNA5322, miR-19b-3p and MAPK1 were explored. Furthermore, a mouse model was established to detect the roles of lncRNA5322, miR-19b-3p, and MAPK1 in wound contraction and epidermal regeneration. Over-expressed lncRNA5322 was found to promote proliferation, colony formation ability but inhibit apoptosis of HFSCs, in addition to up-regulation of the expression of CDK1 and CDK2. LncRNA5322 was found to act as a ceRNA of miR-19b-3p which directly targeted MAPK1. Furthermore, up-regulation of lncRNA5322 enhanced wound contraction and epidermal regeneration in vivo by increasing the expression of MAPK1 through functioning as a ceRNA of miR-19b-3p. In summary, the results in this study suggested that lncRNA5322 serves as a ceRNA of miR-19b-3p to elevate the expression of MAPK1, ultimately promoting HFSCs proliferation, wound contraction and epidermal regeneration of mouse model.

The Wnt/β-Catenin/LEF1 Pathway Promotes Cell Proliferation at Least in Part Through Direct Upregulation of miR-17-92 Cluster

The miR-17-92 cluster is involved in animal development and homeostasis, and its dysregulation leads to human diseases such as cancer. In the present study, we investigated the functional link between miR-17-92 cluster and Wnt/β-catenin signaling pathway in ICP2 and DF1 cells. We demonstrated that ectopic expression of either LEF1 or β-catenin increased the promoter activity of the miR-17-92 cluster host gene (MIR17HG) and combined ectopic expression of LEF1 and β-catenin further enhanced the promoter activity; while knockdown of either LEF1 or β-catenin reduced the MIR17HG promoter activity. Both LEF1 and β-catenin could directly bind to the MIR17HG promoter. Furthermore, we demonstrated that low doses of lithium chloride (LiCl), an activator of Wnt/β-catenin signaling pathway, increased MIR17HG promoter activity and the endogenous expression of the miR-17-92 cluster, while high doses of LiCl had the opposite effects. Treatment with XAV-939, an inactivator of the Wnt/β-catenin pathway, reduced the endogenous expression of miR-17-92 cluster. Finally, we found that low doses of LiCl promoted the proliferation of ICP2 and DF1 cells, while high doses of LiCl inhibited the proliferation of ICP2 and DF1 cells. Taken together, our results reveal that MIR17HG is a target of LEF1 and the Wnt/β-catenin pathway and suggest that the miR-17-92 cluster may, at least in part, mediate the proliferation-promoting effect of the Wnt/β-catenin pathway in cell proliferation.

The Role of MicroRNAs in the Regulation of Gastric Cancer Stem Cells: A Meta-Analysis of the Current Status

Gastric cancer (GC) remains one of the major causes of cancer-related mortality worldwide. As for other types of cancers, several limitations to the success of current therapeutic GC treatments may be due to cancer drug resistance that leads to tumor recurrence and metastasis. Increasing evidence suggests that cancer stem cells (CSCs) are among the major causative factors of cancer treatment failure. The research of molecular CSC mechanisms and the regulation of their properties have been intensively studied. To date, molecular gastric cancer stem cell (GCSC) characterization remains largely incomplete. Among the GCSC-targeting approaches to overcome tumor progression, recent studies have focused their attention on microRNA (miRNA). The miRNAs are short non-coding RNAs which play an important role in the regulation of numerous cellular processes through the modulation of their target gene expression. In this review, we summarize and discuss recent findings on the role of miRNAs in GCSC regulation. In addition, we perform a meta-analysis aimed to identify novel miRNAs involved in GCSC homeostasis.

An overview of the multifaceted roles of miRNAs in gastric cancer: Spotlight on novel biomarkers and therapeutic targets

MicroRNAs (miRNAs) are a group of small non-coding RNAs that have displayed strong association with gastric cancer (GC). Through the repression of target mRNAs, miRNAs regulate many biological pathways that are involved in cell proliferation, apoptosis, migration, invasion, metastasis as well as drug resistance. The detection of miRNAs in tissues and in body fluids emerges as a promising method in the diagnosis and prognosis of GC, due to their unique expression pattern in correlation with GC. Notably, miRNAs are also identified as potential therapeutic targets for GC therapy. The present review is thus to highlight the multifaceted roles of miRNAs in GC and in GC therapies, which would give indications for future research.

MiR-145 negatively regulates TGFBR2 signaling responsible for sepsis-induced acute lung injury

This study aims to explore the roles of miR-145/TGFBR2 axis in sepsis-induced acute lung injury. Here, RNA-sequencing assay showed that miR-145 was significantly decreased in exosomes from sepsis patient blood samples. And miR-145 was decreased but TGFBR2 was increased in LPS-treated mice lung tissues or BEAS-2B cells in a time-dependent manner. Mechanistically, TGFBR2 was identified as a direct target of miR-145 and the downstream effector Smad3 was also suppressed in BEAS-2B cells with miR-145 overexpression. Pre-injection or post-injection of miR-145 agomir following LPS treatment attenuated LPS-induced inflammation, characterized as the downregulation of IL-2 and TNF-α secretion and ameliorate sepsis, and prolonged the overall survival of septic mice with lung injury. Additionally, TGFBR2 overexpression partially abrogated miR-145-mediated inhibition on LPS-induced inflammation and sepsis-induced acute lung injury. Importantly, TGF-β (Transforming growth factor-β) and miR-145 level displayed a negative correlation in sepsis patients. Thus, these results suggest that miR-145 could ameliorate sepsis-induced lung injury via inhibiting TGFBR2 signaling.

Identification of non-invasive biomarkers for chronic atrophic gastritis from serum exosomal microRNAs

BACKGROUND

Serum exosomal microRNAs (miRNAs) have been suggested as novel biomarkers for various diseases, especially gastric cancer (GC). But circulating biomarkers for Chronic atrophic gastritis (CAG) which is defined as precancrerous lesions of GC remain largely elusive. To investigate serum exosomal miRNAs that are differently expressed in CAG patients and Chronic nonatrophic gastritis (CNAG) may be helpful for its diagnosis and therapy.

METHODS

Patients were recruited according to the diagnosis and exclusioncriteria. RNA was extracted from serum exosomes of 30 CAG and 30 CNAG patients. The miRNA expression profiles were analyzed by next generation sequencing and were validated by qRT-PCR. Receiver operating characteristic (ROC) analysis has been used to evaluate the diagnostic value.

RESULTS

30 CAG patients and 30 CNAG patients were recruited in our study. sRNA-seq results showed that hsa-miR-3591-3p, - 122-3p, and - 122-5p of the top 10 miRNAs (hsa-miR-148a-3p, - 122-3p, - 486-3p, -451a, - 122-5p, - 3591-3p, - 486-5p, -151a-3p, -92a-3p, -320a) were significantly upregulated in exosomes from CAG patients versus those from CNAG patients, but hsa-miR-451a, -151a-3p, and -92a-3p were significantly downregulated. Furthermore, qRT-PCR analysis confirmed that hsa-miR-122-5p and hsa-miR-122-3p were significantly upregulated in CAG samples, but hsa-miR-122-3p hadnot a steable expression. ROC curves showed that the AUC for hsa-miR-122-5p was 0.67 (95% CI 0.52-0.82, SE 62%, SP 86%). A sum of the four miRNAs (panel 1, hsa-miR-122-5p, -451a, -151a-3p, and -92a-3p) did not significantly improve the diagnostic potential (AUC 0.63, 95% CI 0.47 to 0.78). Correlation analysis showed that the expression of hsa-miR-122-5p differed significantly between patients based on atrophic (Moderate atrophic vs. Absent, P value was 0.036.) and IM (compare moderate-severe, absent and mild P values were 0.001 and 0.014, respectively). However, there were no differences between groups based on age, gender, dysplasia, or chronic or active inflammation.

CONCLUSION

These results suggested that hsa-miR-122-5p in serum exosomes might serve as a potential biomarker for CAG diagnosis.

TRIAL REGISTRATION

Chinese Clinical Trial Registy ( ChiCTR-IOR-16008027 , Date of Registration:2016-03-01).

MicroRNA-17, MicroRNA-19b, MicroRNA-146a, MicroRNA-302d Expressions in Hepatoblastoma and Clinical Importance

Hepatoblastoma (HB) is the most common liver malignancy in children. The prognosis changes according to the histologic subtypes of HB. In the present study, we aimed to characterize the expression level of selected microRNAs (miRNAs) in HB as well as in histologic subtypes, and to consider the association with the prognosis. A total of 22 HB tumor samples, subtyped as fetal (n=16) and embryonal (n=6), and 10 nontumorous surrounding liver samples were evaluated in this study. Expressions of miR-17, miR-146a, miR-302d, and miR-19b were analyzed in 22 HB tumor samples and 10 nontumorous surrounding liver samples by quantitative real-time polymerase chain reaction. Lower miRNA-17 expression levels were obtained in tumor samples in comparison with nontumorous surrounding liver samples (P=0.028). Lower miRNA-17 expression was significant for predicting prognosis in HB patients (area under receiver-operator characteristic curve=0.875, P=0.044). A higher-level of miR-19b was found in embryonal samples (P=0.008). Overall and event-free survival was not found to correlate with miRNA expression levels (P>0.05). This research finds miRNA-17 and miRNA-19b expression levels can provide important data on diagnosis and prognosis in HB showing different clinical behaviors.

MicroRNA-19a regulates the proliferation, migration and invasion of human gastric cancer cells by targeting CUL5

Gastric cancer is one of the prevalent types of cancers and despite improvements in its treatment, the overall survival is still far from descent. The dearth of efficient biomarkers, chemotherapeutic agents and therapeutic targets form a major hurdle in the treatment of the gastric cancer. Accumulating evidences suggest that MicroRNAs (miRs) may prove important therapeutic targets/agents for the management of cancers including gastric cancer. Herein, we examined the expression of miR-19a by qRT-PCR in gastric cancer and attempted to explore its potential role. It was found that the expression of miR-19a is significantly (p < 0.05) enhanced in the gastric cancer tissues as well as the gastric cancer cell lines. Inhibition of miR-19a in gastric cancer cells suppressed the proliferation migration and invasion of the gastric cancer cells. Bioinformatic analysis revealed CUL5 to be the potential target of miR-19a. Contrary, to the expression of miR-19a, the expression of CUL5 was significantly (p < 0.05) downregulated in all the gastric cancer tissues and cell lines. However, inhibition of miR-19a in SNU-16 gastric cancer cells could cause upsurge of CUL5 expression. Overexpression of CUL-5 was found to exhibit similar effects on the proliferation, migration and invasion of the SNU-16 gastric cancer cells as that of miR-19a suppression. Additionally, overexpression of CUL5 could at least partially abolish the effects of miR-19a suppression on the proliferation, migration and invasion of SNU-16 gastric cancer cells. Finally, overexpression of miR-19a caused inhibition of the xenografted tumors in vivo indicating the potential of miR-19a as therapeutic target for gastric cancer.

MiR-1-5p is down-regulated in gallbladder carcinoma and suppresses cell proliferation, migration and invasion by targeting Notch2

BACKGROUND

Numerous studies have demonstrated that aberrant microRNAs (miRNAs) are involved in tumorigenesis and tumor progression. Nevertheless, the precise role of miR-1-5p in gallbladder carcinoma cell growth and metastasis remains not fully revealed.

MATERIAL AND METHODS

The levels of miR-1-5p were detected in gallbladder carcinoma tissues and cell lines using qRT-PCR method. A series of functional assays, including cell proliferation, colony formation, wound healing and Transwell invasion were conducted using miR-1-5p or miR-1-5p inhibitor transfected cells.

RESULTS

MiR-1-5p was remarkably down-regulated in gallbladder carcinoma tissues and cell lines compared to normal. In addition, over-expression of miR-1-5p markedly suppressed the growth, migration and invasion of gallbladder carcinoma cell. Conversely, down-expression of miR-1-5p facilitated gallbladder carcinoma cell proliferation and aggressiveness. Mechanistic investigations demonstrated that neurogenic locus notch homolog protein 2 (Notch2) was the directly target of miR-1-5p and Notch2 mediated the inhibitory effect of miR-1-5p in gallbladder carcinoma cell growth and aggressiveness.

CONCLUSION

Our findings demonstrated that miR-1-5p acted as a suppressive miRNA and played vital roles in the growth, migration and invasion of gallbladder carcinoma cell through targeting Notch2.

Gastric Cancer Stem Cells: Mechanisms and Therapeutic Approaches

Gastric cancer (GC) is the third leading cause of cancer-related deaths worldwide. GC stem-like cells (GCSCs), with unlimited self-renewal, differentiation, and tumor-regenerating capacities, contribute significantly to the refractory features of GC and have gained increasing attention for their role in GC drug resistance, relapse, and metastasis. Therapies targeting GCSCs seem to be one of the most promising methods to improve the outcomes of GC patients. Extensive investigations have attempted to outline the regulatory mechanisms in GCSCs and to develop GCSCs-targeting therapies with which to diminish GC drug resistance, metastasis and relapse. To the best of our knowledge, there is a lack of reviews summarizing these studies. In this review, we systematically recapitulated findings regarding the regulatory mechanisms of GCSCs, as well as therapies that target GCSCs, hoping to support the development of prognostic biomarkers and GCSCs-targeting anticancer therapies in GC.

miR-199b-5p-Stonin 2 axis regulates metastases and epithelial-to-mesenchymal transition of papillary thyroid carcinoma

Papillary thyroid carcinoma is one of the most fatal malignant endocrine tumors, and the prognosis remains poor because of the lack of effective therapeutic targets. In this study, we demonstrated that the level of miR-199b-5p was markedly downregulated in papillary thyroid carcinoma. The ectopic expression level of miR-199b-5p in papillary thyroid carcinoma cell B-CPAP could inhibit growth, migration, and invasion as well as epithelial-mesenchymal transition (EMT) and decreased cell metastasis in vivo, but silencing miR-199b-5p caused a contradictory outcome. Additionally, Stonin 2 (STON2) was identified as a direct target gene of miR-199b-5p. Consistent with the downregulation of miR-199b-5p, the overexpression of STON2 induced the growth, migration and invasion of B-CPAP cells. It was also demonstrated that miR-199b-5p suppressed papillary thyroid carcinoma cell aggressiveness by targeting STON2. Furthermore, the overexpression of miR-199b-5p inhibited cell proliferation, promoted apoptosis, and increased the chemo-sensitivity of thyroid carcinoma B-CPAP cells toward the chemotherapy drug paclitaxel. Finally, in vivo experiments further demonstrated that miR-199b-5p suppressed tumor growth in nude mice. Thus, this study revealed that miR-199b-5p functions as antioncogene miRNA in papillary thyroid carcinoma cells and that the miR-199b-5p/STON2 axis might be a potential treatment option for papillary thyroid carcinoma. © 2018 IUBMB Life, 71(1):28-40, 2019.

miR-17-92 functions as an oncogene and modulates NF-κB signaling by targeting TRAF3 in MGC-803 human gastric cancer cells

The miR-17-92 cluster plays either an oncogenic or anti-oncogenic role in cancer progression in diverse human cancers. However, the underlying mechanisms of the miR-17-92 cluster in gastric cancer have not yet been fully elucidated. In this study, the function of the miR-17-92 cluster in diverse aspects of MGC-803 gastric cancer cells was systematically elucidated. The enforced introduction of the miR-17-92 cluster into the MGC-803 cells significantly promoted cell growth due to the increased cellular proliferation and decreased cellular apoptosis, which were detected by CCK-8, cell viability and TUNEL assays. Moreover, the results of western blot analyses revealed that the activated protein kinase B (AKT), extracellular-signal-regulated kinase (ERK) and nuclear factor (NF-κB) signaling pathways were activated in these processes. Moreover, the overexpression of the miR-17-92 cluster markedly enhanced the migratory and invasive abilities of the MGC-803 cells, which was associated with the occurrence of epithelial-mesenchymal transition (EMT). Tumor necrosis factor receptor associated factor 3 (TRAF3), which negatively regulates the NF-κB signaling pathway, was identified as a direct target of miR-17-92. Furthermore, TRAF3 silencing enhanced the oncogenic functions of the miR-17-92 cluster in the MGC-803 cells, including the increased cellular proliferation, migration and invasion. Moreover, immunohistochemical staining and survival analyses of a gastric cancer tissue microarray revealed that TRAF3 functioned as a tumor suppressor in gastric cancer. Taken together, the findings of this study provide new insight into the specific biological functions of the miR-17-92 cluster in gastric cancer progression by directly targeting TRAF3.

miR-17-92 cluster is connected with disease progression and oxaliplatin/capecitabine chemotherapy efficacy in advanced gastric cancer patients: A preliminary study

This study aimed to determine the role of plasma miR-17-92 cluster level in predicting chemoresistance in patients with gastric cancer (GC) undergoing oxaliplatin/capecitabine (XELOX) chemotherapy.Patients recently diagnosed with advanced GC were chosen as participants based on the inclusion criteria. The plasma levels of miR-17-5p, miR-18a, miR-19a/b, miR-20a, and miR-92-1 (miR-17-92 cluster) were determined through quantitative RT-PCR of blood samples from GC patients and healthy volunteers. All the patients received XELOX chemotherapy, and the effectiveness of the chemotherapy was evaluated.The miR-17-92 plasma level was increased in advanced GC patients and decreased after XELOX chemotherapy. Moreover, the miR-17-92 cluster level was associated with chemotherapy response but not with chemotherapy-related toxicity. The miR-17-92 cluster plasma level was decreased in chemosensitive patients, but not in chemoresistant patients, after chemotherapy. The sensitivity and specificity of the combined detection of the miR-17-92 cluster in patients with advanced GC were 100% each.The results suggest that the miR-17-92 plasma level is associated with the progression of advanced GC and effectiveness of XELOX chemotherapy.

miR-19 in blood plasma reflects lung cancer occurrence but is not specifically associated with radon exposure

Radon is one of the most powerful carcinogens, particularly in terms of lung cancer onset and development. miRNAs may be considered not only as markers of the ongoing tumorigenesis but also as a hallmark of exposure to radiation, including radon and its progeny. Therefore, the purpose of the present study was to estimate the value of plasma miR-19b-3p level as the prospective marker of the response to radon exposure in lung cancer pathogenesis. A total of 136 subjects were examined, including 49 radon-exposed patients with lung cancer, 37 patients with lung cancer without radon exposure and 50 age/sex matched healthy controls. Total RNA from blood samples was extracted and used to detect miR-19b-3p expression via reverse transcription quantitative-polymerase chain reaction. The 2-ΔΔCq method was used to quantify the amount of relative miRNA. The plasma level of p53 protein was determined using a Human p53 ELISA kit. Plasma miR-19b-3p level was significantly higher in the patients with lung cancer groups, compared with the healthy control group (P<0.0001). No other statistically significant differences were determined in the expression level of plasma miR-19b-3p between patients diagnosed with lung cancer exposed to radon and not exposed to radon. The expression level of free circulating miR-19b-3p was higher in the group of non-smoking patients with lung cancer, compared with smokers with lung cancer. The miR-19b-3p was 1.4-fold higher in non-smokers than in smokers (P<0.05). No association between plasma levels of p53 protein and miR-19b-3p freely circulating in patients with lung cancer was observed. No other statistically significant differences were determined in the plasma p53 protein level between patients diagnosed with lung cancer exposed and not exposed to radon. These results indicated that detection of miR-19b-3p levels in plasma potentially could be exploited as a noninvasive method for the lung cancer diagnostics. However, this miRNA is not suitable as the precise marker for radon impact.

miRNA-103a-3p Promotes Human Gastric Cancer Cell Proliferation by Targeting and Suppressing ATF7 in vitro

Studies have revealed that miR-103a-3p contributes to tumor growth in several human cancers, and high miR-103a-3p expression is associated with poor prognosis in advanced gastric cancer (GC) patients. Moreover, bioinformatics analysis has shown that miR-103a-3p is upregulated in The Cancer Genome Atlas (TCGA) stomach cancer cohort. These results suggest that miR-103a-3p may function as an oncogene in GC. The present study aimed to investigate the role of miR-103a-3p in human GC. miR-103a-3p expression levels were increased in 33 clinical GC specimens compared with adjacent nontumor stomach tissues. Gain- and loss-of-function studies were performed to identify the correlation between miR-103a-3p and tumorigenesis in human GC. Inhibiting miR-103a-3p suppressed GC cell proliferation and blocked the S-G2/M transition in MKN-45/SGC-7901 cells, whereas miR-103a-3p overexpression improved GC cell proliferation and promoted the S-G2/M transition in vitro. Bioinformatics and dual-luciferase reporter assays confirmed that ATF7 is a direct target of miR-103a-3p. Analysis of the TCGA stomach cancer cohort further revealed that miR-103a-3p expression was inversely correlated with ATF7 expression. Notably, silencing ATF7 showed similar cellular and molecular effects as miR-103a-3p overexpression, namely, increased GC cell proliferation, improved CDK2 expression and decreased P27 expression. ATF7 overexpression eliminated the effects of miR-103a-3p expression. These findings indicate that miR-103a-3p promotes the proliferation of GC cell by targeting and suppressing ATF7 in vitro.

Clustered miRNAs and their role in biological functions and diseases

MicroRNAs (miRNAs) are endogenous, small non-coding RNAs known to regulate expression of protein-coding genes. A large proportion of miRNAs are highly conserved, localized as clusters in the genome, transcribed together from physically adjacent miRNAs and show similar expression profiles. Since a single miRNA can target multiple genes and miRNA clusters contain multiple miRNAs, it is important to understand their regulation, effects and various biological functions. Like protein-coding genes, miRNA clusters are also regulated by genetic and epigenetic events. These clusters can potentially regulate every aspect of cellular function including growth, proliferation, differentiation, development, metabolism, infection, immunity, cell death, organellar biogenesis, messenger signalling, DNA repair and self-renewal, among others. Dysregulation of miRNA clusters leading to altered biological functions is key to the pathogenesis of many diseases including carcinogenesis. Here, we review recent advances in miRNA cluster research and discuss their regulation and biological functions in pathological conditions.

The miR-17-92 cluster as a potential biomarker for the early diagnosis of gastric cancer: evidence and literature review

Purpose

Intestinal metaplasia is considered to be a pre-cancerous lesion of gastric cancer. The miR-17-92 cluster was previously reported to have clinical value in the prediction of cancer development. This study aimed to test the diagnostic value of miR-17-92 in gastric cancer and the intestinal metaplasia patients compared with the normal ones.

Results

The results showed that miR-17-92 members were over-expressed in the serum of both gastric cancer and intestinal metaplasia patients, compared with healthy controls. Serum miR-17-92 members could also distinguish patients with gastric cancer and intestinal metaplasia from healthy controls.

Materials and Methods

Serum miR-17-92 expression levels were detected using quantitative real-time PCR in 75 patients with gastric cancer, 104 patients with intestinal metaplasia and 38 healthy controls. The Receiver operating characteristic (ROC) curves and the area under the ROC curve (AUC) were then analyzed to test the efficacy of the miR-17-92 members in distinguishing gastric cancer, intestinal metaplasia and healthy controls.

Conclusions

In conclusion, the miR-17-92 cluster might be useful as a potential serum biomarker for the early detection of gastric cancer.

LncRNA MT1JP functions as a ceRNA in regulating FBXW7 through competitively binding to miR-92a-3p in gastric cancer

Background

Emerging evidence has shown that dysregulation function of long non-coding RNAs (lncRNAs) implicated in gastric cancer (GC). However, the role of the differentially expressed lncRNAs in GC has not fully explained.

Methods

LncRNA expression profiles were determined by lncRNA microarray in five pairs of normal and GC tissues, further validated in another 75 paired tissues by quantitative real-time PCR (qRT-PCR). Overexpression of lncRNA MT1JP was conducted to assess the effect of MT1JP in vitro and in vivo. The biological functions were demonstrated by luciferase reporter assay, western blotting and rescue experiments.

Results

LncRNA MT1JP was significantly lower in GC tissues than adjacent normal tissues, and higher MT1JP was remarkably related to lymph node metastasis and advance stage. Besides, GC patients with higher MT1JP expression had a well survival. Functionally, overexpression of lncRNA MT1JP inhibited cell proliferation, migration, invasion and promoted cell apoptosis in vitro, and inhibited tumor growth and metastasis in vivo. Functional analysis showed that lncRNA MT1JP regulated FBXW7 expression by competitively binding to miR-92a-3p. MiR-92a-3p and down-regulated FBXW7 reversed cell phenotypes caused by lncRNA MT1JP by rescue analysis.

Conclusion

MT1JP, a down-regulated lncRNA in GC, was associated with malignant tumor phenotypes and survival of GC. MT1JP regulated the progression of GC by functioning as a competing endogenous RNA (ceRNA) to competitively bind to miR-92a-3p and regulate FBXW7 expression. Our study provided new insight into the post-transcriptional regulation mechanism of lncRNA MT1JP, and suggested that MT1JP may act as a potential therapeutic target and prognosis biomarker for GC.

Electronic supplementary material

The online version of this article (10.1186/s12943-018-0829-6) contains supplementary material, which is available to authorized users.

Down-regulation of microRNA-19b in hormone receptor-positive/HER2-negative breast cancer

miR-19b (miR-19b-3p) has been reported to be correlated with either favorable or unfavorable events in several cancers. However, no study has been conducted to evaluate the expression level of miR-19b in patients with breast cancer (BC). This study was aimed to investigate the expression level of miR-19b in human malignant and healthy breast tissues with histopathology of ER+/PR+/HER2-. We performed a miRNA real-time PCR to detect differential expression of miR-19b in 40 BC, including 17 BC with familial background and 23 BC without familial background, and 12 non-tumoral tissues. Moreover, a bioinformatics prediction upon miR-19b functionality in BC cells was performed. The miR-19b expression level was significantly down-regulated in BC, BC with familial background, and BC without familial background compared with its expression in normal tissue (p value, <0.0001; fold change, -7.45; p value, 0.0003; fold change, -6.45; and p value, 0.0005; fold change, -8.41, respectively). Moreover, according to the AUCs (area under curve) of receiver operating characteristic (ROC) curves, miR-19b can significantly distinguish all defined categories. Last, in agreement with our experimental findings, proteoglycans in cancer, pathways in cancer, FoxO signaling pathway, central carbon metabolism in cancer, p53 signaling pathway, transcriptional misregulation in cancer, and prolactin signaling pathway were predicted as miR-19b-related signaling pathways. In summary, down-regulation of miR-19b in BC vs healthy tissue suggests that mir-19b can function as a tumor suppressor. Our results shed additional information on controversial expression pattern of miR-19b depending on different cancer types.

miR-19a/b and MeCP2 repress reciprocally to regulate multidrug resistance in gastric cancer cells

Despite the improvement in gastric cancer (GC) treatment, multidrug resistance (MDR) is still a significant reason for chemotherapy failure. Our previous studies have demonstrated that miR-19a/b upregulation directly promoted MDR in GC cells. However, the exact regulation and the potential molecule mechanisms have not been fully clarified. In this study, we found that miR-19a/b was directly involved in 5-aza-2'-deoxycytidine (5-Aza-dC) induced MDR of GC cells. Mechanically, demethylation of miR-19a/b repressed methyl CpG binding protein 2 (MeCP2) expression via direct binding at the 3'-untranslated regions, which then alleviated the inhibitory effects of MeCP2 on miR-19a/b expression. Thus, the mutual regulatory network sustains preservation of the expression levels of miR-19a/b. We further demonstrated that miR-19a/b expression was inversely correlated to MeCP2 expression in GC tissues. These data showed an intimate interplay among miR-19a/b methylation, MeCP2 activity, and MDR, revealing a potential therapeutic target for GC.

Biology of MiR-17-92 Cluster and Its Progress in Lung Cancer

MicroRNAs, a class of short endogenous RNAs, acting as post-transcriptional regulators of gene expression, mostly silence gene expression via binding imperfectly matched sequences in the 3'UTR of target mRNA. MiR-17-92, a highly conserved gene cluster, has 6 members including miR-17, miR-18a, miR-19a, miR-20a, miR-19b-1 and miR-92a. The miR-17-92 cluster, regarded as oncogene, is overexpressed in human cancers. Lung cancer is the leading cause of death all over the world. The molecular mechanism of lung cancer has been partly known at the levels of genes and proteins in last decade. However, new prognosis biomarkers and more target drugs should be developed in future. Therefore, noncoding RNAs, especially miRNAs, make them as new potentially clinical biomarkers for diagnosis and prognosis. In this review, we focus the current progress of miR-17-92 cluster in lung cancer.

MiR-17-5p and miR-20a promote chicken cell proliferation at least in part by upregulation of c-Myc via MAP3K2 targeting

The miR-17-92 cluster has been well studied in mammals but less extensively studied in birds. Here, we demonstrated that miR-17-92 cluster overexpression promoted the proliferation of DF1 cells and immortalized chicken preadipocytes (ICPA-1), and miR-17-5p and miR-20a, members of the miR-17-92 cluster, targeted MAP3K2. Further analysis showed that MAP3K2 overexpression reduced the proliferation of DF1 and ICPA-1 cells and attenuated the promotive effect of the miR-17-92 cluster on cell proliferation. Downstream gene expression analysis of the MAPK signalling pathway showed that MAP3K2 overexpression decreased c-Myc expression; in contrast, MAP3K2 knockdown using RNA interference and miR-17-92 cluster overexpression increased c-Myc expression. Furthermore, c-Myc overexpression promoted miR-17-92 cluster expression and DF1 cell proliferation. Taken together, these data indicated that miR-17-92 promotes chicken cell proliferation at least in part by the upregulation of c-Myc via targeting MAP3K2, and the miR-17-92 cluster, c-Myc and E2F1 form a complex regulatory network in chicken cell proliferation.

miRNA-4317 suppresses human gastric cancer cell proliferation by targeting ZNF322

Studies have shown that miR-4317 is dysregulated in tumor, but the biologic role of miR-4317 in tumor development and progression remains unknown. The present study aimed to investigate the role of miR-4317 in human gastric cancer. Quantitative real-time PCR was used to quantify miR-4317 expression levels in clinical gastric cancer specimens and cell lines. MTT, colony formation and cell cycle assays were performed to identify the contributions of miR-4317 to cell proliferation in gastric cancer cell lines. The results showed that miR-4317 was significantly decreased in 17 clinical gastric cancer specimens compared with adjacent non-tumor stomach tissues. Forced expression of miR-4317 suppressed gastric cancer cell proliferation and blocked S-G2/M transition. Bioinformatics and dual-luciferase reporter assays confirmed that ZNF322 is a direct target of miR-4317. Silencing ZNF322 recapitulated the cellular and molecular effects seen upon miR-4317 overexpression. These findings indicate that miR-4317 represses the proliferation of gastric cancer cell, at least in part, by targeting and suppressing ZNF322 and that it may serve as a therapeutic target for gastric cancer treatment.

MiR-92a promotes stem cell-like properties by activating Wnt/β-catenin signaling in colorectal cancer

We previously reported the oncogenic function of miR-92a in colorectal cancer. This study identified that miR-92a was upregulated in chemoresistant colorectal cancer cells and tissues. Ectopic expression of miR-92a conferred resistance to 5-fluorouracil-induced apoptosis in vitro, while antagomiR-92a significantly enhanced chemosensitivity in vivo. Moreover, Overexpression of miR-92a promoted the tumor sphere formation and the expression of stem cell markers. MiR-92a overexpression also displayed higher tumourigenesis in vivo. Furthermore, we demonstrated that miR-92a upregulates the Wnt/β-catenin signaling activity via directly targeting KLF4, GSK3β and DKK3, which are multiple level negative regulators of the Wnt/β-catenin signaling cascade. In addition, our results indicate IL-6/STAT3 pathway increases miR-92a expression by directly targeting its promoter, resulting in Wnt/β-catenin signaling activation and consequent promotion of stem-like phenotypes of colorectal cancer cells. Our present results suggest the essential role of IL-6/STAT3/miR-92a/Wnt/β-catenin pathway in regulating the stem cell-like traits of colorectal cancer cells and provide a potential target for colorectal cancer therapy.

A serum exosomal microRNA panel as a potential biomarker test for gastric cancer

The findings from several studies have suggested that circulating miRNAs are imbalanced with the genesis of gastric cancer (GC). Both normal and cancer cells can generate and secrete exosomes, which are nanosized membrane vesicles that can transport microRNAs and proteins. Emerging evidence indicates that the exosomes secreted by cancer cells can be released into the circulatory system. In this study, we investigated whether circulating exosomal miRNAs can be used to discriminate individuals with GC from healthy controls (NCs). Based on the quantitative reverse transcription polymerase chain reaction (qRT-PCR), four miRNAs (miR-19b-3p, miR-17-5p, miR-30a-5p, and miR-106a-5p) related to GC pathogenesis were identified in serum-circulating exosomes from a cohort of 20 healthy controls and 20 individuals with GC in the initial screening phase. The distinguished miRNAs were further validated in the training (90 GC vs. 90 NCs) and blinded phases 20 GC vs. 20 NCs), and the area under receiver operating characteristic (ROC) curves of these miRNAs were analyzed. We found that miR-19b and miR-106a were markedly overexpressed in individuals with GC compared to NCs (P < 0.0001). Besides, the ROC analyses yielded the AUC values of 0.786 for miR-106a-5p, 0.769 for miR-19b-3p and combined ROC analysis revealed the highest AUC value of 0.814 in discriminating GC patients from NCs. Furthermore, based on the model developed from the data, a signature composed of the 2 miRNAs (miR-19b-3p and miR-106a-5p) correctly discriminated 19 out of 20 GC serum samples (95% sensitivity) and 18 out of 20 normal samples (90% specificity) in the blinded phase. Moreover, the validated miRNAs were related to GC lymphatic metastasis (P < 0.01) and expressed at higher levels in stages III and IV compared to I and II stages (P < 0.05). These results suggest that serum exosomal miR-19b-3p and miR-106a-5p are novel potential biomarkers for detecting GC.